MEMCAL
John Marshall Williamson
Mwnofial
QUAIN'S ANATOMY.
QUAIN'S
ELEMENTS OF ANATOMY
EDITED BY
WILLIAM SHARPEY, M.D, F.E.S.
PROFESSOR OF ANATOMY AND PHYSIOLOGY IN UNIVERSITY COLLEGE, LONDON
ALLEN THOMSON, M.D., F.R.S.
PROFESSOR OF ANATOMY IN THE UNIVERSITY OF GLASGOW
AND
JOHN CLELAND, M.D.
PROFESSOR OF ANATOMY IN QUEEN'S COLLEGE, GALWAY
IN TWO VOLUMES
ILLUSTRATED BY UPWARDS OF 800 ENGRAVINGS ON WOOD.
VOL. II.
LONDON
JAMES WALTON
BOOKSELLER AND PUBLISHER TO UNIVERSITY COLLEGE
137, GOWKR STREET.
1867.
LONDON :
BRADBURY, EVANS, AND CO., PRINTERS, WHITEFRTARS.
5 •.•*•••" •.!.***••••
CONTENTS OF THE SECOND VOLUME.
DIVISION L— SYSTEMATIC AND DESCRIPTIVE ANATOMY
(CONTINUED).
PAGE
SECTION V.— NEUROLOGY . 501
I. THE CEREBRO-SPINAL Axis . 501
A. THE SPINAL CORD . . . 502
Its description . . . 5°2
Internal structure . . . 507
Central Canal . . . 5°8
Minute structure of the Cord . 509
Origin of the Spinal Nerves . 511
B. THE ENCEPHALON . . . 513
The Medulla Oblongata . . 514
Course of fibres through the
Medulla . . . . 518
Grey matter of the Medulla 5 19
The Pons Varolii and Cerebel-
lum 521
Pons Varolii . . .521
The Cerebellum . . . 522
Its internal structure . 526
The Cerebrum . . . . 529
Exterior of the Cerebrum . 529
Cerebral Convolutions . 531
Base of the Cerebrum . . 53^
Internal parts of the Cere-
brum . . . . 54°
Lateral Ventricles . . 543
Third Ventricle . • • 55°
Internal Structure of the
Cerebrum . . . 554
"White matter . . . 555
Grey matter . . , 559
Membranes of the Brain and
Spinal Cord . . . 562
Dura Mater . . .562
Pia Mater . . . . 564
Arachnoid Membrane . . 565
Blood-vessels of the Brain and
x Spinal Cord . . .567
Size and Weight of the Ence-
phalon .... 568
Weight of the several parts of
the Encephalon . . . 571
Weight of the Spinal Cord . 572
Specific Gravity of the Ence-
phalon . . . .572
Development of the Cerebro-
Spinal Axis . . .
of the Spinal Cord
of the Encephalon . . .
of the membranes of the En-
cephalon.
II. THE CEREBRO-SPINAL NERVES
A. CRANIAL NERVES
Connections of the Cranial
Nerves with the Encephalon
Distribution of the Cranial
Nerves . ...
Olfactory Nerve
Optic Nerve . . . .
Third Pair of Nerves .
Fourth Pair of Nerves . .
Fifth Pair of Nerves
Ophthalmic Nerve . . .
Lachrymal Branch .
Frontal Branch . . .
Nasal Branch .
Ophthalmic Ganglion . .
Superior Maxillary Nerve .
Orbital branch
Posterior Dental Branches
Anterior Dental Branch .
Infraorbital Branches
Spheno - palatine Gang-
lion . . . .
Inferior Maxillary Nerve .
Deep Temporal, Masse-
teric, Buccal, and Ptery-
goid Branches . .
Auriculo-temporal Nerve
Gustatory Nerve . .
Inferior Dental Nerve
Otic Ganglion
Submaxillary Ganglion .
Sixth Pair of Nerves
Seventh Pair of Nerves . .
Facial Nerve
Connecting Branches . .
ChordaTyinpani and Nerve
to the Stapedius .
Posterior Auricular Branch
PAGE
573
574
575
581
582
582
583
587
592
592
593
594
595
597
597
59
5
599
600
600
60 1
60 1
602
603
605
605
606
606
608
608
609
610
610
610
611
611
612
VI
CONTENTS.
PAGE
Digastric and Stylo-hyoid
Branches . . .613
Temporo-facial Division . 613
Cervico-facial Division . 613
Auditory Nerve . . .615
Eighth Pair of Nerves . . 615
Glosso-pharyngeal Nerve . 615
Connecting Branches and
Tympanic Branch . 616
Branches distributed in
the Neck . . . 617
Pneumo-gastric Nerve . 618
Connecting Branches and
Auricular Branch . 621
Pharyugeal Branch . .621
Superior Laryngeal Branch 621
Recurrent Laryngeal
Branch . . .622
Cardiac Branches . . 623
Pulmonary Branches . 623
(Esophageal Branches . 623
Gastric Branches . . 623
Spinal Accessory Nerve . . 625
Ninth Pair of Nerves . . 626
Connecting Branches . . 626
Muscular and Lingual
Branches . . . 626
B. SPINAL NERVES . . . . 628
Roots of the Spinal Nerves . 630
Posterior Primary Divisions of
the Spinal Nerves . . 632
Suboccipital Nerve . . 632
Cervical Nerves . . . 633
Dorsal Nerves . . . 634
Lumbar Nerve . . . 634
Sacral Nerves . . .635
Coccygeal Nerve . . . 635
Anterior Primary Divisions of
the Spinal Nerves . . 635
Cervical Nerves . . . 636
Suboccipital Nerve . . 636
Second Cervical Nerve . 636
Cervical Plexus . . . 636
1. Superficial Ascending
Branches . . 638
Superficial Cervical
Nerve . . .638
Great Auricular Nerve 638
Small Occipital Nerve 638
2. Superficial Descending
Branches . . 639
Supraclavicular Nerves 639
3. Deep Branches : Inner
Series . . 640
Muscular Branches 640
Phrenic Nerve . 640
4. Deep Branches : Exter
nal Series . 641
Brachial Plexus . . 641
Branches above the Cla
vicle . . . 643
Posterior Thoracic Nerve 644
Suprascapular Nerve . 644
Branches below the Clavicle 644
PAGE
Anterior Thoracic Nerve 645
Subscapular Nerve . 645
Circumflex Nerves . 645
Internal Cutaneous
Nerve . . . . 646
Small Internal Cuta-
neous Nerve . . 646
Musculo- cutaneous
Nerve . . . 648
Ulnar Nerve . . 648
Median Nerve . . 649
Musculo-spiral Nerve 652
Radial Nerve . . 653
Posterior Interosseous
Nerve . .^ . . 654
Anterior Primary Divisions of
the Dorsal Nerves . -655
First Dorsal Nerve . . 655
Upper or Pectoral Intercostal
Nerves . -655
Lower or Abdominal Inter-
costal Nerves . . . 657
Last Dorsal Nerve . . 658
Anterior Primary Divisions of
the Lumbar Nerves . 658
Lumbar Plexus . . . 658
Ilio-hypogastric and Ilio-
inguinal Nerves . . 660
Genito- crural Nerve . . 660
External Cutaneous Nerves 662
Obturator Nerve . . 662
Accessory Obturator Nerve 663
Anterior Crural Nerve . 664
Muscular Branches . . 665
Middle Cutaneous Nerve 665
Internal Cutaneous
Nerve . . . 665
Internal Saphenous
Nerve . . . 666
Fifth Lumbar Nerve . . 667
Superior Gluteal Nerve . 667
Anterior Primary Divisions of
the Sacral and Coccygeal
Nerves .... 668
The Sacral Nerves . . . 668
Fourth Sacral Nerve . . 668
Fifth Sacral Nerve . . 668
Coccygeal Nerve . . 668
Sacral Plexus . . . 669
Muscular Branches . .670
Pudic Branches . . . 670
Small Sciatic Nerve . 673
Great Sciatic Nerve . . 675
Internal Popliteal Nerve 676
External or Short Saphe-
nous Nerve . . 677
Posterior Tibial Nerve 677
Internal Plantar Nerve 677
External Plantar Nerve 679
External Popliteal or
Peroneal Nerve . 679
Musculo -cutaneous
Nerve . . . . 680
Anterior Tibial Nerve . 68 1
CONTEXTS.
Vll
Synopsis of the Cutaneous Dis-
tribution of the Cerebro-
spinal Nerves . . . 682
Synopsis of the Muscular Dis-
tribution of the Cerebro-
spinal Nerves . . . 684
Muscles of the Head and
Fore Part of the Neck . 684
Muscles belonging exclu-
sively to the Trunk, and
Muscles ascending to the
Skull 684
Muscles attaching the Upper
Limb to the Trunk . . 685
Muscles of the Upper Limb 685
Muscles of the Lower Limb 686
III. SYMPATHETIC NERVES . . 686
A. GANGLIATED CORDS . . 688
Cervical Part . . . . 688
Upper Cervical Ganglion . 688
Ascending Branch and
Cranial Plexuses . . 688
Pharyngeal Nerves and
Plexus . . . . 690
Upper Cardiac Nerve . 690
Branches to Blood-vessels 692
Middle Cervical Ganglion . 692
Lower Cervical Ganglion . 693
Thoracic Part . . . 693
Branches of the Ganglia . 693
Great Splanchnic Nerve . 695
Small Splanchnic Nerve . 696
Smallest Splanchnic Nerve . 696
Lumbar Part . . . 696
Sacral Part . . . . 696
Coccygeal Gland . .697
B. GREAT PLEXUSES OF THE SYM-
PATHETIC . . . 698
Cardiac Plexus . . . 698
Superficial . . . . 698
Deep 698
Solar or Epigastric Plexus . 699
Aortic Plexus . . . 702
Hypogastric Plexus . . . 702
Pelvic Plexus . . .703
IV. ORGANS OF THE SENSES . . 705
THE EYE 705
Appendages of the Eye . . 705
Eyelids and Conjunctiva . 705
Lachrymal Apparatus . . 709
Globe of the Eye . . .710
External Coat of the Eyeball . 711
Sclerotic Coat . . .711
Cornea . . ... 714
Middle Tunic of the Eyeball . 716
Choroid Coat . . .716
Iris 718
Ciliary Muscle, Ligamentum
Pectinatum, and Circular
Sinus . . . .721
Vessels and Nerves of the
Middle Tunic of the Eye . 721
Retina or Nervous Tunic . 725
Structure of the Retina . 726
PAGE
Vitreous Body . . . . 731
The Lens and its Capsule . 733
Lens 733
Suspensory Ligament of the
Lens, and Canal of Petit 736
Aqueous Humour and its
Chamber . . . 736
Development of the Eye . 736
THE EAR 740
External Ear .... 740
Pinna 740
External Auditory Canal . 743
Middle Ear or Tympanum . 744
Small Bones of the Ear . 748
Ligaments and Muscles of
Tympanum . . . 749
Lining Membrane of Tym-
panum . . . • 751
Vessels and Nerves of Tym-
panum . . . . 752
Internal Ear or Labyrinth . 753
Osseous Labyrinth . . 753
Membranous Labyrinth . 757
Vestibule . . . • 757
Semicircular Canals . . 75&
Cochlea 760
Blood-vessels of Labyrinth . 767
Development of the Ear . 768
NOSE 771
Cartilages of Nose . . .771
Nasal Fossae . . . . 773
Mucous Membrane . . 774
Development of the Nose . . 778
SECTION VI. — SPLANCHNO-
LOGY 779
ORGANS OF DIGESTION . . 779
Mouth 779
Teeth 780
Structure . ... 784
Development of Teeth . 792
Tongue 805
Mucous Membrane . . 805
Muscular substance . . 809
Palate 813
Tonsils 813
Salivary Glands . . .815
Parotid Gland . . . 815
Submaxillary Gland . . 816
Sublingual Gland . . . 817
Pharynx .... 819
(Esophagus . . . . 821
Abdominal Digestive Organs . 823
Abdomen ..... 823
Parts situated in each Re-
gion of the Abdomen . 826
The Peritoneum . . . 826
Stomach .... 830
Structure of coats . . 832
Small Intestine . . .838
Structure of Small Intes-
tine . . . . 841
Large Intestine . . . 851
Caecum . ... 852
viii
CONTENTS.
PAGE
Colon .... 853
Rectum . . . . 856
Anus and its Muscles . 859
Development of the Alimentary
Canal and Peritoneal Cavity 859
Liver ..... 862
Structure of Liver . . . 869
The Bile . . . .878
Development and Foetal
Peculiarities of Liver . 879
Pancreas . . . . . 88 1
Spleen 883
ORGANS OF RESPIRATION . . 888
Trachea and Bronchi . . 888
Structure of the Trachea . 890
Pleurae 892
Lungs .... 894
Root of Lung . . . 897
Structure of Lungs . . 898
Development of Lungs and
Trachea .... 904
Larynx or Organ of Voice . . 905
Cartilages of Larynx . . 905
Muscles of Larynx . . . 914
Vessels and Nerves of Larynx 919
Development and Growth of
Larynx . . . -919
DUCTLESS GLANDS ON THE
LARYNX AND TRACHEA . 920
Thyroid Body . . . 920
Thymus Gland . . . 923
URINARY ORGANS . . . 926
Kidneys .... 926
Suprarenal Bodies . . . 939
PAGE
944
952
952
952
952
955
956
958
959
963
963
Ureters ....
Urinary Bladder . . .
Urethra ....
ORGANS OF GENERATION . .
MALE ORGANS
Prostate Gland . . .
Penis ....
Corpora Cavernosa . .
Corpus Spongiosum
Urethra of the Male . .
Testes and Excretory Appa-
ratus ....
Coverings of Testis and
Cord ....
Vessels and Nerves of the
Coverings of the Testis
and Cord . . . 967
Testes . . . . 967
Vas Deferens . . . 971
Seminal Vesicles and
Ejaculatory Ducts . . 973
Vessels and Nerves of
Testis. . . .975
FEMALE ORGANS . . . 977
Vulva .... 977
Female Urethra . . . 980
Vagina .... 980
Uterus . ... 982
Ovaries and Fallopian Tubes 988
Development of the Urinary
Organs .... 992
Development of the Organs
of Generation . . . 995
MAMMARY GLANDS . . 1002
DIVISION II.— SURGICAL ANATOMY.
SURGICAL ANATOMY OF THE
ARTERIES
Common Carotid Artery
Subclaviau Artery
Brachial Artery .
Common Iliac Arteries
Internal Iliac Artery .
External Iliac Artery
Femoral Artery .
SURGICAL ANATOMY OF THE PARTS
1005
1005
,1007
1010
1012
1014
1014
IOI5
CONCERNED IN CERTAIN ABDO-
MINAL HERNLE . . . 1018
The Parts concerned in Inguinal
Hernia ..... 1018
Inguinal Hernise . . . . 1025
The Parts concerned in Femoral
Hernia 1031
Femoral Hernia . . . . 1034
THE PERINEUM AND ISCHIO-RECTAL
REGION 1037
Lateral Operation of Lithotomy 1043
DIVISION III.— DISSECTIONS.
GENERAL MANAGEMENT OF THE
DISSECTIONS .... 1047
SPECIAL DIRECTIONS FOR THE DIS-
SECTION OF EACH PART
Head and Neck
1048
1048
Upper Limbs or Superior Extre-
mities . . . . . 1059
Thorax 1066
Abdomen and Pelvis . . . 1069
Lower Limbs or Inferior Extre-
mities 1078
NEUROLOGY.— CEREBRO-SPINAL AXIS. 501
SECTION V.— NEUROLOGY.
UNDER the name of Neurology, it is intended to include the descriptive
anatomy of the various organs forming parts of the nervous system.
The nervous system consists of two sets of parts, one of which is eentral,
the other peripheral. To the first set belong the brain and spinal cord,
forming together the cerebro-spinal axis, and the ganglia : to the second
set belong all the nerves distributed throughout the body ; and along with
these may be included the organs of the senses, or those organs which
contain the terminations of the several nerves of special sensation, in con-
nection with certain apparatus or modifications of structure related to the
reception of impressions by each of these nerves.
Among the peripheral nerves it is necessary also to distinguish the cere-
bro-spinal and the sympathetic or ganglionic, which, though intimately
connected with each other at some places, are yet so different in their
structure and mode of distribution as to require separate description.
The description of these several parts of the nervous system will be
brought under the following four subsections, viz. 1. The cerebro-spinal
axis ; 2. The cerebro-spinal nerves and the ganglia connected with them ;
3. The sympathetic nerves and their ganglia ; 4. The organs of the
senses.
I.— THE CEREBRO-SPINAL AXIS.
The cerebro-spinal axis is contained partly within the cavity of the cra-
nium, and partly within the vertebral canal ; it is symmetrical in its form
and structure throughout, consisting of a right and a left half, separated
to a certain extent by longitudinal fissures, and presenting in their plane of
union various portions of white and grey nervous substance which cross
from one side to another, and form the commissures of the brain and spinal
cord.
Enclosed within the skull and the vertebral canal, the cerebro-spinal axis
is protected by the bony walls of those tw6 cavities ; it is also surrounded
by three membranes, which afford it additional protection and support, and
are subservient to its nutrition. These envelopes, which will be described
hereafter, are, 1st, a dense fibrous membrane named the dura mater, which
is placed most superficially ; 2nd, a serous membrane called the arach-
noid ; and, 3rd, deepest of all, a highly vascular membrane named the pia
mater.
The cerebro-spinal axis is divided by anatomists into the encephalon or
enlarged upper mass placed within the cranium, and the spinal cord con-
tained within the vertebral canal.
These two parts have a relation, one to the other, very similar to that
which subsists between the cranium and vertebral column : thus, they are
continuous structures ; at the time of their first formation in the foetus they
are nearly similar ; the earliest developed distinction consists in the enlarge-
ment of the encephalon ; and, moreover, the spinal cord, like the vertebral
column, continues to present a structure nearly uniform throughout its
extent, while the encephalon becomes gradually more and more complicated,
502
THE SPINAL COED.
till at last it is difficult to trace the
serial relation of its constituent
parts, or any correspondence with
the structure of the cord.
Fig. 339. — VIEW OP THE CEREBRO-
SPINAL AXIS OF THE NERVOUS SYSTEM
(after Bourgery). -g-
The right half of the cranium and
trunk of the body has been removed by
a vertical section ; the membranes of the
brain and spinal marrow have also been
removed, and the roots and first part of
the fifth and ninth cranial, and of all
the spinal nerves of the right side, have
been dissected out and laid separately on
the wall of the skull and on the several
vertebrae opposite to the place of their
natural exit from the cranio-spinal
cavity.
F, T, 0, lateral surface of the
cerebrum ; C, cerebellum ; P, pons
Varolii ; m o, medulla oblongata ; m s,
upper and lower extremities of the spinal
marrow ; c e, on the last lumbar ver-
tebra, marks the cauda equina ; v, the
three principal branches of the nervus
trigeminus or fifth pair ; C I, the sub-
occipital or first cervical nerve ; above
this is the ninth pair ; C vm, the eighth
or lowest cervical nerve ; D I, the first
dorsal nerve ; D xii, the last or twelfth ;
L i, the first lumbar nerve ; L v, the last
or fifth ; S I, the first sacral nerve ; S v,
the fifth ; Coi, the coccygeal nerve ; st
the left sacral plexus.
A.— THE SPINAL CORD.
The spinal cord, or spinal marrow
(medulla spinalis), is that part of
the cerebro- spinal axis which is
situated within the vertebral canal.
It extends from the margin of the
foramen magimm of the occipital
bone to about the lower part of the
body of the first lumbar vertebra.
It is continued into the medulla
oblongata above, and ends below
in a slender filament, the filum
terminale or central ligament of the
spinal cord.
Invested closely by a proper
membrane (the pia mater), the
cord is enclosed within a sheath
(theca) considerably longer and
larger than itself, which is formed
by the dura mater, and which is
separated from the walls of the
THE SPINAL CORD.
503
canal by numerous vascular plexuses, and
much loose areolar tissue. The interval
between the investing membrane and the
sheath of the cord is occupied by a serous
membrane (the arachnoid), and the space
between the latter membrane and the pia
mater is occupied by a fluid called the
cerebro-spinal fluid. Within this space
the cord is kept in position by proper
ligaments, which fix it at different points
to its sheath, and by the roots of the
spinal nerves, — an anterior and a pos-
terior root belonging to each, — which
pass across the space from the surface of
the cord towards the intervertebral fora-
mina. From its lower part, where they
are closely crowded together, the roots
of the lumbar and sacral nerves descend
nearly vertically to reach the lumbar
intervertebral and the sacral foramina,
and form a large bundle or lash of
nervous cords named the cauda equina,
which occupies the vertebral canal below
the termination of the cord.
A Fig. 340.
-7 C
10
Fig. 340. — ANTERIOR AND POSTERIOR VIEWS OP
THE MEDULLA OBLONGATA AND SPINAL CORD
WITH SECTIONS. ^
The cord has been divested of its membranes
and the roots of the nerves. A, presents an
anterior, B, a posterior view, showing the upper
or brachial, and the lower or crural enlargements.
In these figures the filiform prolongation, repre-
sented separately in B', has been removed ; C,
shows a transverse section through the middle of
the medulla oblongata ; D, a section through the
middle of the cervical enlargement of the spinal
cord ; E, through the upper region of the dorsal
part ; F, through its lower ; Gr, through the
middle of the lumbar enlargement ; and H, near
the lower end of its tapering extremity.
1, anterior pyramids ; 1', their decussation ;
2, olivary bodies ; 3, restiform bodies ; 4, pos-
terior surface of the medulla oblongata ; 4', cala-
mus scriptorius ; 5, posterior pyramids ; 6, pos-
terior lateral columns passing up into the restiform
bodies ; 7, 7, anterior median fissure extending
through the whole length of the spinal cord ; 8, 8,
anterior lateral groove ; 9, 9, posterior median
fissure; 10, 10, posterior lateral groove; x,
lower end of the tapering extremity of the cord ;
x , x , in B', the filiform prolongation of the
cord and its pia-matral covering.
Although the cord usually ends near the
lower border of the body of the first lumbar
vertebra, it sometimes terminates a little above
or below that point, as opposite to the last
10-
504
THE SPINAL COED.
dorsal or to the second lumbar vertebra. The position of the lower end of the cord also
varies according to the state of curvature of the vertebral column, in the flexion
forwards of which, as in the stooping posture, the end of the cord is slightly raised.
In the foetus, at an early period, the cord occupies the whole length of the vertebral
canal ; but, after the third month, the canal and the roots of the lumbar and sacral
nerves begin to grow more rapidly than the cord itself, so that at birth the lower end
reaches only to the third lumbar vertebra.
Fig. 341. — POSTERIOR VIEW OP THE MEDULLA OBLONGATA AND OP THE SPINAL CORD
WITH ITS COVERINGS AND THE ROOTS OF THE NERVES (from Sappey). 4
The theca or dura-matral sheath has been opened by a median incision along the whole
length, and is stretched out to each side. On the left side, in the upper and middle parts
(A and B), the posterior roots of the nerves have been removed so as to expose the liga-
mentum denticulatum ; and along the right side the roots are shown passing out through
the dura mater. The roman numbers indicate the different nerves in the cervical, dorsal,
lumbar, and sacral regions : 9, several of the pointed processes of the ligamentum den-
ticulatum ; 10, origin of several posterior roots ; 11, posterior median fissure ; 12,
ganglia of the spinal nerves ; 13, part of the anterior roots seen on the left side ; 14,
the united nerve ; 15, tapering lower end of the spinal cord; 16, filum terminale; 17,
cauda equina.
The length of the spinal cord is from fifteen to eighteen inches ; and it
varies in diameter in different situations. Its general form is cylindrical,
somewhat flattened before and behind. It presents two enlargements — an
upper or cervical, and a lower or lumbar. The cervical enlargement is of
greater size and extent than the lower. It reaches from the third cervical
to the first dorsal vertebra ; its greatest diameter is from side to side.
FORM AXD POSITION OF THE COED.
505
The lower or lumbar enlargement is situated nearly opposite the last dorsal
vertebra ; its antero-posterior diameter is nearly equal to the transverse.
Below this enlargement, the cord tapers in
the form of a cone, from the apex of which Fig. 342.
the small filiform prolongation is continued
downwards for some distance within the
sheath.
Fig. 342. — LOWER PART OP THE SPINAL CORD WITH
THE CAUDA EO.UINA AND SHEATH, SEEN FROM BE-
HIND. £
The sheath has been opened from behind and
stretched towards the sides ; on the left side all the
roots of the nerves are entire ; on the right side both
roots of the first aud second lumbar nerves are entire,
while the rest have been divided close to the place of
their passage through the sheath. The bones of the
coccyx are sketched in their natural relative position
to show the place of the filum terminale and the lowest
nerves.
a, placed on the posterior median fissure at the
middle of the lumbar enlargement of the cord ; b, £,
the terminal filament, drawn slightly aside by a hook
at its middle, aud descending within the dura-matral
sheath ; b', b', its prolongation beyond the sheath
and upon the back of the coccygeal bones ; c, the
dura-matral sheath ; d, double foramina for the
separate passage of the anterior and posterior roots of
each of the nerves ; e, pointed ends of several pro-
cesses of the ligamentum denticulatum ; Dx, and
DXII, the tenth and twelfth dorsal nerves ; Li, and
Lv, the first and fifth lumbar nerves; Sr, and Sv,
the first and fifth sacral nerves; Ci, the coccygeal
nerve.
The cervical and lumbar enlargements have an
evident relation to the large size of the nerves
which supply the upper and lower limbs, and which
are connected with those regions of the cord, — in
accordance with the general fact observed in the
animal kingdom, that, near the origin of large nerves,
the central nervous substance is accumulated in
larger proportion. At the commencement of its
development in the embryo the spinal cord is des-
titute of these enlargements, which, in their first
appearance and subsequent progress, correspond
with the growth of the limbs.
Sometimes the cord presents one or two bulbs or
swellings towards its lower end.
According to Foville, the lumbar enlargement is
chiefly due to an increase in bulk of the anterior
region of the cord. (Trait6 compl. de 1'Anat., &c.,
du Syst. Nerv. Cerebro-Spinal. Paris, 1844. Part
I., p. 138.)
"DXD
Li
St
The terminal filament (filum terminale, cen-
tral ligament) descends in the middle line
amongst the nerves composing the cauda
equina, and, becoming blended with the lower end of the sheath opposite to
the first or second sacral vertebra, passes on to be fixed to the lower end of
L L
606 THE SPINAL COED.
the sacral canal, or to the base of the coccyx. Internally, it is a prolongation
for about half its length of some of the nervous elements of the cord ;
externally, it consists of a tube of the pia mater or innermost membrane,
which, being attached at its lower end to the dura mater and vertebral
canal, keeps pace with the latter in its growth, whilst the cord relatively
shortens. It is distinguished by its silvery hue from the nerves amid which
it lies. Small blood-vessels may sometimes be seen upon it.
Fissures. — When removed from the vertebral canal, and divested of its
membranes, the spinal cord is seen to be marked by longitudinal fissures.
Of these, two, which are the most obvious, run along the middle line,
one in front and the other behind, and are named the anterior and pos-
terior median fissures.
The anterior median fissure is more distinct than the posterior, and pene-
trates about one-third of the thickness of the cord, its depth increasing
towards the lower end. It contains a fold or lamelliform process of the pia
mater, and also many blood-vessels, which are thus conducted to the centre
of the cord. At the bottom of this fissure is seen the transverse connecting
portion of white substance named the anterior white commissure.
The posterior median fissure is less marked in the greater part of its
extent than the anterior, but becomes more evident towards the upper part
of the cord. In a certain sense it is no real fissure, except at the lumbar
enlargement and in the cervical region, in both of which places a superficial
fissure is distinctly visible ; for, although the lateral halves of the posterior
part of the cord are quite separate, there is no distinct reflection of the pia
mater between them, but rather a septum of connective tissue and blood-
vessels which passes in nearly to the centre of the cord, as far as the posterior
grey commissure.
Besides these two median fissures, two lateral furrows or fissures have
been described on each side of the cord, corresponding with the lines of
attachment of the anterior and posterior roots of the spinal nerves.
The posterior lateral fissure is a superficial depression along the line of
attachment of the posterior roots, and is at the edge of the plane in which
these roots pass inwards to the grey matter of the cord.
The anterior lateral fissure, which is often described in the line of the
origin of the anterior roots of the nerves, has no real existence as a groove.
The fibres of these roots in fact, unlike the posterior, do not dip into the
spinal cord in one narrow line, but spread over a space of some breadth.
The grey substance of the cord, however, approaches the surface somewhat
in the vicinity of the place where the anterior roots enter : and this, together
with a slight depression, produces the appearance which has been described
as a groove. Thus, each lateral half of the cord is divided by the posterior
lateral fissure into a posterior and an antero-lateral column ; and although
we cannot trace an anterior lateral fissure, this antero-lateral portion of the
cord may, for the convenience of description, be considered as subdivided
into an anterior and a lateral column by the internal grey matter.
On the posterior surface of the cord, and most evidently in the upper
part, there are two slightly marked longitudinal furrows situated one on
each side, close to the posterior median fissure, and marking off, at least in
the cervical region, a slender tract, named the posterior median column..
Between the anterior and posterior roots of the spinal nerves, on each side,
the cord is convex, and sometimes presents a longitudinal mark correspond-
ing with the line of attachment of the ligamentum denticulatum.
Foville states, that in a new-born child there is a narrow accessory bundle of white
INTERNAL STRUCTURE OF THE CORD.
507
matter, which runs along the surface of the lateral column, and is separated from it
by a streak of greyish substance. According to the same authority, this narrow tract
enlarges above, and may be traced upwards along the side ot the medulla oblongata
into the cerebellum. (Op. cit. p. 285.)
Fig. 343.
Fig. 343. — DIFFERENT
VIEWS OF A PORTION OF
THE SPINAL CORD FROM
THE CERVICAL REGION
WITH THE ROOTS OP
THE NERVES. Slightly
enlarged.
In A, the anterior sur-
face of the specimen is
shown, the anterior nerve -
root of the right side
being divided ; in E, a
view of the right side is
given ; in C, the upper
surface is shown ; in D,
the nerve-roots and gan-
glion are shown from
below. 1, the anterior
median fissure ; 2, pos-
terior median fissure ; 3,
anterior lateral depres-
sion, over which the ante-
rior nerve-roots are seen
to spread ; 4, posterior
lateral groove, into which
the posterior roots are
seen to sink ; 5, anterior
roots passing the ganglion ;
5', in A, the anterior root
divided; 6, the posterior roots, the fibres of which pass into the ganglion, 6' ; 7, the
united or compound nerve ; 7', the posterior primary branch seen in A and D, to be
derived in part from the anterior and in part from the posterior root.
Internal structure of the spinal cord. — The spinal cord consists of white
aiid grey nervous substance. The white matter, forming by far the larger
portion of the cord, is situated externally, whilst the grey matter is dis-
posed in the interior.
The grey matter, as seen in a transverse section of any part of the cord,
presents two crescent-shaped masses, placed one in each lateral half, with their
convexities towards one another, and joined across the middle by a transverse
portion, the grey or posterior commissure of the cord. Each of these grey
crescents has an anterior and a posterior cornu or horn. The posterior,
generally longer and narrower, approaches the posterior lateral fissure : the
anterior, shorter and thicker, extends towards the place of attachment of the
anterior roots of the nerves. In front of it a layer of white substance
separates it from the bottom of the anterior median fissure, this is named
the anterior white commissure.
Another white layer, very thin and indistinct, was formerly described as lying
behind the grey commissure; but in the present state of our knowledge it seems
sufficient to describe one white commissure, and one grey commissure behind it.
At the back part or tip of the posterior horn, which is somewhat en-
larged, the grey matter has a peculiar semitransparent aspect, whence it
was named by Rolando substantia cinerea gelatinosa : the remaining and
L L 2
508
THE SPINAL CORD.
greater part of the grey matter, which resembles that most generally preva-
lent, was named by Rolando the substantia spongiosa.
The grey cornua vary in form in different parts of the cord : thus they
are long and slender in the cervical portion, still more slender in the dor-
sal, and shorter and wider in the lumbar region. The grey matter appears
in a series of sections to be, relatively to the white, more abundant in the
lumbar region of the cord, less so in the cervical region, and least so in the
dorsal. The actual amount, however, of white matter is greatest in the
neck. Towards the lower end of the cord, the double crescentic form
gradually disappears, and the grey matter is collected into a central mass,
which is indented at the sides. At its extreme point, according to Remak
and Valentin, the cord consists of grey matter only.
Fig. 344.
Fig.
344. — SECTIONS OF THE SPINAL
CORD IN DIFFERENT PARTS.
These views are taken partly from
Stilling's plates and partly from nature.
A, is a section through the middle of the
cervical enlargement, at the root of the
sixth cervical nerve; B, through the mid-
dle of the dorsal cylindrical portion ; C,
through the middle of the lumbar enlarge-
ment ; D, in the conical diminishing part
of the cord ; E, farther down at the
origin of the fifth sacral nerve ; F, at
that of the coccygeal nerve ; Gf, is a sec-
tion of the part where the conus medul-
laris begins to pass into the filum termi-
nale ; and H, at the lower part of this
or in the commencement of the filum
terminale.
A, B, and C, are fully twice the natural
size ; D, E, and F, about three times ;
and Gr and H, about six times. In A,
and C, a, marks the .interior root- fibres
of the nerves ; and p, the posterior root-
fibres as they enter the spinal cord. In
D, E, and F, the great diminution of the
white substance in proportion to the grey
is seen ; in G-, the peculiar form of the
central canal and medullary substance
covering it ; and in H, the open con-
dition of the central canal posteriorly.
In all the figures the position is the
same, viz., the anterior part placed down-
wards.
Central canal. — Extending through the whole length of the spinal cord,
in the substance of the grey commissure, there is a minute central canal
which in prepared transverse sections of the cord is barely visible, as a
speck, with the naked eye. Superiorly, it is continued into and opens out
at the calamus scriptorius of the fourth ventricle ; and inferiorly, it is
prolonged into the filum terminale. It is lined with a layer of cylindrical
ciliated cells or epithelium. This canal, though minute, is an object of
considerable interest as a typical part of the structure of the cord, it being
the permanent remains of the cavity of the cylinder formed by the spinal
cord at the earliest period of its development. It is more distinctly seen
MINUTE STRUCTURE OF THE CORD.
509
iu fishes, reptiles, and birds than in mammals. In the young human subject
it is always present, but, according to the observation of Lock hart Clarke
and Kolliker, it sometimes disappears in the adult.
Minute Structure of the Spinal Cord. — The substance of the spinal cord consists of a
large proportion of nervous substance, supported in a delicate framework of connective
tissue and numerous minute blood-vessels. The white matter presents nerve-fibres,
but is destitute of nerve-cells • the grey matter contains both elements. The fibres
of the white substance are in greatest part longitudinal; the principal exceptions
being those contained in the commissure, and in the roots of the nerves. The longi-
tudinal fibres are finer in the posterior columns and posterior parts of the lateral
columns than in other parts, and the deepest fibres are smaller than those placed more
superficially. (Kolliker.) The fibres of the grey substance are for the most part not
more than one half the diameter of their continuations in the white substance, and in
the nerve-roots, but among them there are a few of larger size. They are very
various in their direction, and, in great part at least, are connected with the roots of
the nerves.
Fig. 345.— TRANSVERSE Fig. 345.
SECTION OP HALF THE
SPINAL MARROW IN
THE LUMBAR EN-
LARGEMENT, f
This is a semidia-
grammatic representa-
tion taken from a pre-
pared specimen, and
founded in part on the
statements of Lockhart
Clarke and of Kolliker.
1, anterior median
fissure ; 2, posterior
median fissure ; 3, cen-
tral canal lined with
epithelium ; 4, posterior
commissure ; 5, anterior
commissure ; 6, posterior
column ; 7, lateral co-
lumn ; 8, anterior co-
lumn ; (at each of these
places and throughout
the white substance the
trabecular prolongations
of the pia mater are
shown ; ) 9, posterior
roots of the spinal nerve
entering in one principal
bundle; 10, anterior
roots entering in four
spreading bundles of
fibres ; a, a, caput cornu
posterioris with large
and small cells, and above them the gelatinous substance ; b, in the cervix cornu, decus-
sating fibres from the nerve roots and posterior commissure ; c, posterior vesicular
columns (of Clarke) ; d, fibres running transversely from the posterior commissure into
the lateral columns : near d, the lateral group of cells ; e, e, fibres of the anterior
roots entering the anterior cornu, and passing through among the radiating cells, but
not joining their processes; e', fibres from the anterior roots which decussate in the
anterior column ; e", external fibres from the roots running round the outside of the
anterior grey cornu towards the lateral columns ; f, fibres from the posterior commissure
and from the posterior cornu running towards the anterior. Three groups of cells are seen
in the anterior column ; of these the anterior are external and internal, the posterior are
chiefly external or lateral.
510
THE SPIXAL CORD.
The nerve-cells of the grey matter are of two kinds. Firstly, there are very large
branched cells, from ^ to ^ of an inch in size, containing nuclei and pigment ;
secondly, there are smaller cells, ranging from ^^ to ^ of an inch, but the majority
are from -^^ to ~ of an inch in size.
The smaller cells occur scattered throughout the whole of the grey matter ; the
larger cells, on the contrary, are collected into groups. In the posterior cornua the
large cells are almost entirely collected into a compact group, the posterior vesicular
column of Clarke (the core of Stilling), which occupies the inner half of the cervix of
the posterior cornu. This vesicular column is in intimate connection with the
posterior roots of the nerves ; it may be traced continuously from near the lower
extremity of the spinal cord to the middle of the cervical enlargement, where it
terminates ; and it increases in size in both the lumbar and cervical enlargements.
In the anterior cornu the large cells occur in greater number than in the posterior
cornu, and are of somewhat greater size ; and they are principally placed at its forepart,
and arranged in an inner and an outer group. There is likewise described by Clarke a
small group of cells, collected in a tractus intermedio-lateralis, and forming a projection
of the grey matter opposite the junction of the anterior and posterior cornua. This
lateral vesicular column extends from the upper part of the lumbar to the lower part
of the cervical enlargement ; and it may be said to reappear at the upper extremity
of the cord, where it is traversed by the roots of the spinal accessory nerve, and is
continued up into the medulla oblongata.
Fig. 346.
Fig. 346. — A SMALL PORTION OF A TRANSVERSE SECTION OP THE HUMAN SPINAL CORD
NEAR THE SURFACE AT THE ENTRANCE OP A BUNDLE OF THE ANTERIOR ROOTS. ^
This figure, which is somewhat diagrammatic, is intended to show the relation to the
nervous substance of the pia-matral sheath of the cord and the processes of connective
tissue prolonged from it between the longitudinal and other nerve fibres, a, a, the
primitive filaments of a bundle of the anterior roots, the medullary sheaths not repre-
sented ; b, b, transverse sections of part of the anterior columns of the cord in which the
dark points are the primitive filaments, and the circles represent the neurilemmal tube
enclosing the medullary substance : in these parts the connective tissue is not represented,
and many of the smallest nerve-fibres have also, for the sake of clearness, been omitted ;
c, the pia-matral covering of the cord ; d, one of the compartments of the anterior
column enclosed by septa of connective tissue prolonged from the pia mater, and exhibit-
ing the fine frame-work of connective tissue extending through among the nerve-fibres,
which last have been omitted : there are also indicated among the trabeculse minute
nuclei of connective tissue.
Connective tissue takes part in the structure of the cord to a very considerable
extent. It forms a complete covering surrounding the white substance. In the
inner margin also of the posterior columns, one on each side of the posterior fissure,
two wedge-shaped bands (the bands of Goll) have been distinguished, in which the
MINUTE STRUCTURE OF THE CORD.
511
connective tissue is remarkably abundant, and the nerve-fibres particularly small.
The connective tissue forms also a reticulum (processus reticularis), in which the
longitudinal nerve-fibres are imbedded. In the grey matter the connective tissue is
still more abundant, more especially in the immediate neighbourhood of the central
canal. Much discussion has taken place as to whether the smallest cells already
described are really nervous or belong to the connective tissue. In the present
imperfect state of knowledge of the development of nervous elements, it might be
rash to express a decided opinion on this point ; but it may be stated that, independently
of these, nuclei are figured by Kolliker in the reticulum, and also cells containing
numerous and dividing nuclei in the neighbourhood of the central canal.
Origin of the spinal nerves. — The anterior and posterior roots of the spinal nerves
are attached along the sides of the cord in or near the anterior and posterior lateral
grooves, and opposite to the corresponding cornua of the grey matter ; the posterior
roots in a straight line, and the anterior roots scattered somewhat irregularly upon
the surface (Fig. 345).
The fibres of the anterior roots may be traced into and through the anterior
cornua. They then diverge in different directions. The innermost fibres, after
passing through among the cells in the inner group of the anterior cornu, cross in the
white commissure to the anterior column of the opposite side. Many fibres pass
backwards in the substance of the anterior cornu, where some of them would appear
to form connection with fibres proceeding from other parts of the cord, and others to
spread obliquely upwards and downwards ; while those which are most external
passing through the outer group of cells, reach the lateral column.
Fig. 347. — A SMALL FOR- Fig. 347.
TION OF A TRANSVERSE
SECTION OP THE SPINAL
CORD AT THE PLACE
WHERE TWO BUNDLES OP
THE FIBRES OF THE
ANTERIOR ROOTS PASS
INTO THE GREY SUB-
STANCE. ^P
This figure may be looked
upon as representing the
inner ends of the anterior
roots of the nerves, of
which the outer part is
shown in fig. 346. a, a,
the two bundles of fibres of
the anterior root passing
between the compartments
of longitudinal fibres of the
cord ; b, b, these fibres
running backwards through
the grey substance towards
the posterior cornua ; c, c',
those spreading in the anterior cornua on the one side towards the anterior commissure,
and on the other round the outer side of the anterior cornu ; d, d, portions of three com-
partments of the anterior columns in which the longitudinal fibres of the cord are shown
in transverse section ; e, e, large radiated and nucleated cells in the grey substance of the
anterior cornu — some with three, others with a greater number of processes emanating
from them : no direct communication is shown between these processes and the nerve
fibres of the roots.
The fibres of the posterior roots on reaching the posterior cornu diverge from each
other in a curved manner, so as to form in great part the substantia gelatinosa. In
front of this there may be seen, cut across in transverse sections, a group of these
fibres which turn longitudinally upwards and downwards, and afterwards pass
forwards, in part at least, to the anterior cornu, and in part to reach by the posterior
commissure the posterior and lateral columns of the opposite side. Other fibres of
the posterior roots pass forwards at once through the grey substance to the anterior
512 THE SPINAL CORD.
and lateral columns. Another set of fibres slant principally upwards, but some
downwards, in the posterior columns, and, interlacing with each other, most probably
enter the grey matter at different heights. Some are lost to view in the posterior
white columns, and it is uncertain whether or not they immediately ascend through
these columns to the brain.
Much discussion has taken place as to the course of the fibres in the cord, and their
ultimate destination. It is easily understood that, by the examination of sections difficult
to prepare, limited in extent, liable to undergo changes in the preparation, and giving
views confined each to little more than a thin lamina, it is scarcely to be expected that
the full history of many tortuous fibres can be accurately ascertained. Thus it remains
still undecided whether any of the fibres of the nerve-roots pass up all the way to
the brain. Volkmann concluded that none of them reached the brain, arguing from
measurements of the size of the cord in different regions, that the cord could not
contain in its upper regions all those nerve-fibres which were traceable to it in the
lower. Kolliker pointed out the fallacy of this conclusion, in so far as Volkmann
had not made proper allowance for the diminished size of the fibres as they ascend in
the cord ; but although Volkmann's argument was thereby invalidated, it appears
impossible to prove by microscopic observations that fibres of nerve-roots traced into
the grey matter, and observed to emerge into the white matter, do not again re-enter
the grey and terminate there. (Lockhart Clarke, Phil. Trans., 1851,1853, 1859;
Stilling, Neue Unters. u. d. Bau des Ruckenmarks, 1856, 1857; Lenhossec, Neue
Unters. u. d. Bau d. cent. Nervensystems, Vienna, 1855 ; F. Goll, Beitrage z. feineren
Bau d. Ruckenmarks, Zurich, 1860. For a full account of the whole subject, see
Kolliker's Handbucb der Gewebelehre des Menschen, 4th ed., 1863).
It is also undetermined in what relation the nerve-fibres and branched or multipolar
cells of the cord stand to each other. Most are inclined to believe that the radiating
prolongations of the cells are in actual con tinuity with the axial filaments of nerve-fibres,
whether proceeding from nerve-roots or from different parts of the cord itself; and
the direct observation of such continuity has been affirmed by some, as by Schroeder
Van der Kolk. But it is still considered by observers who have given most careful
attention to this investigation that, although such continuity may be regarded as of
the greatest probability, and, although it may be considered as proved in some other
parts of the nervous system, especially in the lower animals, the actual passage of
nerve-fibres into the processes of nerve-cells has not been proved as the result of
actual observation in the spinal cord of man or of mammals.
Results of Experiments. — Seeing the imperfect nature of the knowledge of the
minute structure of the spinal cord as obtained from microscopic observations, it
may be proper to give here a short account of the more important results of
physiological experiments as to the course of the transmission of sensory impressions
and motor influences through it, although it is at present difficult to reconcile them
with the results of anatomical research. For the most important information upon
this subject, derived from vivisection, science is indebted to the researches of Brown-
Se"quard and Schiff.
When the superior or dorsal * half of the cord is divided in animals, sensation still
continues in the hind limbs. Sensation likewise continues after division of the
inferior half of the cord, and even after the superior and inferior parts of the cord
have been divided at different levels in such a manner that the hinder extremity of
the cord may be supposed to communicate with the brain by means of the central grey
matter only. But sensation is abolished by piercing the interior of the cord with an
instrument, and so moving it as to divide as much as possible the grey matter without
injuring the white matter. Moreover, section of the cord and irritation of the cut
surfaces produce no pain, provided that the plane of section be sufficiently removed
from the origins of nerves, as may be accomplished in the cervical region ; but in the
neighbourhood of nerve-roots there is great sensibility. From all these circumstances
it appears probable that the sensory fibres, viz., those of the posterior roots, pass
quickly into the grey substance, and that the grey substance conducts sensory
impressions upwards. Moreover, the circumstance that the posterior as well as the
anterior surfaces of transverse sections made near the nerve-roots are sensitive seems
* The student is reminded that "superior" applied to animals corresponds to
" posterior" applied to the human subject.
THE ENCEPHALON. 513
to be accounted for by the curving of the nerve-roots both toward and away from the
brain. By similar experiments it is made probable that motor impressions likewise
travel chiefly in the grey matter of the cord.
Section of one lateral half of the cord is followed by loss of sensation in the opposite
hind limb, and of motion in the limb of the side operated on : and a prolonged
mesial incision produces loss of sensation in both hind limbs, without paralysis
of motion. But in the medulla oblongata, above the decussation of the anterior
pyramids, section of one side produces loss of both sensation and motion on the
opposite side. From these circumstances it appears probable that the sensory fibres,
viz., those of the posterior roots, decussate in the commissure ot the spinal cord,
while the motor fibres, those derived from the anterior roots, cross chiefly at the
decussation of the anterior pyramids of the medulla oblongata. (For further details,
see Brown-Sequard, " Central Nervous System," 1860; also for a succinct account of
the subject and for bibliography, J. Be"clard, " Physiologic Humaine," 4th ed., 1862 ;
" Carpenter's Human Physiology/' 6th edit., 1865.)
B.— THE ENCEPHALON.
The encephalon admits of being conveniently divided into the medulla
oblougata, the cerebellum with the pons Varolii, and the cerebrum.
Fig. 348.
Fig. 348. — PLAN IN OUTLINE OF THE ENCEPHA.LON, AS SEEN FROM THE RIGHT SIDE. J
The parts are represented as separated from one another somewhat more than natural
so as to show their connections. A, cerebrum ; /, g, h, its anterior middle and posterior
lobes; e, fissure of Sylvius; B, cerebellum; C, pons Varolii; D, medulla oblongata;
a, peduncles of the cerebrum ; b, c, d, superior middle, and inferior peduncles of the
cerebellum ; the parts marked a, b, c, C, form the isthmus encephali.
The medulla ollongata is the part continuous with the spinal cord : it
rests on the basilar process of the occipital bone, and on its superior or
dorsal surface presents a groove continuous with the central canal of the
spinal cord.
The cerebellum occupies the posterior fossa of the cranium. By the
mesial part of its anterior and inferior surface, it forms the roof of a space,
5H THE MEDULLA OBLONGATA.
the floor of which is the grooved posterior surface of the medulla oblongata,
and which is named the fourth ventricle of the brain. Oil each side of
this, the cerebellum is connected with the medulla oblongata and cerebrum,
and also receives the fibres of the pons Parolii, which is a commissure
passing beneath and between the fibres which extend upwards from the
medulla oblongata, so as to unite the two lobes of the cerebellum.
The cerebrum includes all the remaining and much the largest part of the
encephalon. It is united with the parts below by a comparatively narrow
and constricted portion or isthmus, part of which, forming the crura cerebri,
descends into the pons Varolii, and through it is continued into the me-
dulla oblongata, whilst another part joins the cerebellum. Situated on the
fibres which extend up from the constricted part, are a series of eminences,
named, from behind forwards, the corpora quadrigemina, optic thalami, and
corpora striata ; and springing from the front and outer side of the corpora
striata are the large convoluted cerebral hemispheres, which expand from
this place in all directions, concealing the eminences named, and occupying
the vault of the cranium, the anterior and middle cranial fossse, and the
superior fossse of the occipital bone. The cerebral hemispheres are united
together by commissures ; by means of which there is enclosed a cavity,
which is subdivided into various ventricles, viz., the two lateral, the third,
and the fifth.
THE MEDULLA OBLONGATA.
The medulla ollongata is bounded above by the lower border of the pons
Varolii, whilst it is continuous below with the spinal cord, on a level with
the upper border of the atlas, at a point which corresponds with the lower
extremity of the anterior pyramids, to be presently described. It inclines
obliquely downwards and backwards ; its anterior surface rests in the
basilar groove, whilst its posterior surface is received into the fossa
named the vallecula, between the hemispheres of the cerebellum, and
there forms the floor of the fourth ventricle. To its sides several large
nerves are attached.
The term medulla oblongata, as employed by Willis, by Yieussens, and by those
who directly followed them, included the crura cerebri and pons Varolii, as well as
that part between the pons and the foramen magnum, to which, by Haller first, and
by most subsequent writers, this term has been restricted.
It is of a pyramidal form, having its broad extremity directed upwards :
it is expanded laterally at its upper part : its length from the pons to the
lower extremity of the pyramids is about an inch and a quarter ; its
greatest breadth is nearly an inch ; and its thickness, from before back-
wards, is about three-quarters of an inch.
The anterior and posterior mesial fissures which partially divide the spinal
cord are continued up into the medulla oblongata. The anterior fissure
terminates immediately below the pons in a recess, the foramen ccecum of
Vicq d'Azyr ; the posterior fissure is continued upwards into the floor of the
fourth ventricle, where it opens and expands in a superficial furrow, and is
gradually lost.
In other respects an entirely different arrangement of the parts prevails
from that in the cord. The surface of each half of the medulla presents
four eminences or columns, which are met with in the following order,
from before backwards, viz. : the anterior pyramids, the olivary bodies, the
restiform bodies, and the posterior pyramids.
COLUMNS OF THE MEDULLA OBLOXGATA.
515
The anterior pyramids are two bundles of white substance, placed one on
either side of the anterior fissure, and marked off from the olivary body
externally by a slight depression. They become broader and more pro-
minent as they ascend towards the pons Varolii. At their upper end they
are constricted, and thus enter the substance of the pons, through which
their fibres may be traced into the peduncles of the brain.
Fig. 349.
Fig. 349. — VIEW OP THE ANTERIOR SURFACE
OF THE PONS VAROLII AND MEDULLA
OBLONGATA.
a, a, anterior pyramids ; 6, their decussation ;
c, c, olivary bodies ; d, d, restiforra bodies ; e,
arciform fibres ; /, fibres described by Solly as
passing from the anterior column of the cord to
the cerebellum ; gt anterior column of the
spinal cord ; h, lateral column; p, pons Varolii;
i, its upper fibres ; 5, 5, roots of the fifth pair
of nerves.
In the lower part, a portion of each
pyramid, arranged in several bundles,
which interlace with the corresponding
bundles of the other pyramid, passes
downwards across the fissure to the oppo-
site side. This decussation of the pyra-
mids is not complete, but affects much
the greater part of the innermost fibres.
When traced from below, it is found
that the whole or a great part of the
decussating fibres come forward from the
deep portion of the lateral columns of the cord, and advance to the surface
between the diverging anterior columns, which are thus thrown aside.
(Rosenthal, " Beitrag zur Encephalotomie," 1815.)
The outer smaller portion of each pyramid does not decussate ; it consists
of fibres, derived from the anterior column of the cord : these ascend, and
are joined by the decussating portion from the opposite side. Together
they form a prismatic bundle or column of white fibres, which extends
deeply into the substance of the medulla, and is triangular in a cross
section.
The anterior pyramids contain no grey matter.
The olivary bodies are two prominent oval masses placed to the outer sida
of the pyramids, and sunk to a considerable depth in the substance of the
medulla oblongata, appearing on its surface like two smooth oval eminences.
They do not reach the pons Yarolii above, being separated from it by a
deep depression ; nor do they extend so far in a downward direction as the
pyramids, being considerably shorter than those bodies.
The olivary bodies consist externally of white substance, of which the
fibres chiefly run longitudinally ; and internally of a grey nucleus, named
corpus dentatum or ciliare, or olivary nucleus.
The olivary nucleus appears, on making a section, whether horizontal or
vertical, through the middle, to present the form of a zig-zag line of a light
yellowish colour, circumscribing a whitish substance within, and interrupted
towards the centre of the medulla. It is arranged in the form of a capsule,
which is open at its upper and inner part, and has its sides corrugated or
516
THE MEDULLA OBLOXGATA.
plicated, so as to give the indented appearance to a section. This capsule is,
moreover, surrounded with white matter externally, and through its open part
white fibres pass into or issue from its interior, and connect it with other
parts of the brain. The external fibres of the anterior columns of the cord,
which at the decussation of the pyramids are thrown outwards, are con-
tinued upwards, on the surface of the medulla oblongata, and then pass
partly on the outside of and partly beneath the olivary bodies — being joined
in their further progress by the fibres issuing from the olivary nucleus. To
these fibres the term olivary fasciculus has been applied.
The restiform bodies, placed behind and to the outer side of the olivary
bodies, are two lateral rounded eminences or columns directly continuous with
the posterior, and with part of the antero-lateral columns of the cord ; they
diverge slightly as they ascend, and thus occasion the greater width of the
Fig. 350. Fig. 350. — VIEW OF THE POSTERIOR SURFACE OF
THE PONS VAROLII, CORPORA QUADRIGEMINA,
AND MEDULLA OBLONGATA.
The peduncles of tbe cerebellum are cut short
at the side, a, a, the upper pair of corpora quadri-
gemina ; 6, b, the inferior ;/,/, superior peduncles
of the cerebellum ; c, eminence connected with
the nucleus of the hypoglossal nerve; e, that of
the glosso-pharyngeal nerve ; i, that of the vagus
nerve ; d, d, restiform bodies ; p, p, posterior
pyramids ; v, v, groove in the middle of the fourth
ventricle ; v, calamus scriptorius, and eminence
connected with the spinal accessory nerve ; 7, 7,
roots of the auditory nerves. (See also Fig. 357,
at p. 525.)
medulla at its upper part. Each of them
passes into the corresponding hemisphere
of the cerebellum, and constitutes its
inferior peduncle. At first they are in
contact with the small tracts of the
medulla, named the posterior pyramids ;
but higher up they become free and pro-
minent, and assist in forming the lateral boundaries of the fourth ventricle.
There is a considerable portion of grey matter in their interior.
By far the larger portion of the white substance of the restiform body
consists of longitudinal fibres, which include all those belonging to the
posterior column of the cord except the fasciculus gracilis, some derived
from the lateral column, and also a small band from the anterior column.
This last-named band runs obliquely below the olivary body, and, as was
shown by Solly, connects the anterior column with the cerebellum.
The part of the posterior column of the cord which belongs to the resti-
form body of the medulla, is named fasciculus cuneatus.
The posterior pyramids (fasciculi graciles) of the medulla oblongata, the
smallest of the four pairs of columns into which it is divided, are situated
one on each side of the posterior median fissure. They consist entirely of
white fibres, and are continuous with the posterior slender tracts of the
cord. They increase in size as they ascend till they reach the point where
the medulla opens out to form the floor of the fourth ventricle ; and there,
diverging from one another, they have the appearance of tapering and
become closely applied to the restiform bodies. Their fibres quit these
bodies, however, and pass up to the cerebrum.
STEUCTUHE OF THE MEDULLA OBLONGATA. 517
The floor of the fourth ventricle, or space between the medulla and cere-
bellum, is formed by that portion of the back of the medulla oblongata
which is situated above the divergence of the posterior pyramids. Upon it,
the central grey matter of the medulla oblongata, is, as it were, opened out
to view. It is marked by a median furrow, ending inferiorly in the calamus
scri2Jtorius, and at its lower end is a tubular recess, passing down the centre
of the medulla for a few lines. This, which has been sometimes named the
ventricle of Arantius, is the upper expanded portion of the central canal of
the spinal cord.
In the upper part of the floor of the fourth ventricle are two longitudinal
eminences, one on each side of the middle furrow, greyish below, but
appearing white higher up. These are formed by two bundles of white
fibres, mixed with much grey matter, the fasciculi teretes of some authors,
les faisceaux innomines of Cruveilhier. They seem to be derived from part
of the lateral columns of the cord ; Cruveilhier believes, however, that they
arise from the grey matter at the lower end of the medulla oblongata.
Surmounting the free inner margin of the restiform body and posterior
pyramid is a thin lamina, the lifjula (smaller pous of Meckel) occupying the
angle between the cerebellum and the restiform body, and stretching towards
its fellow of the opposite side. It derives a certain interest from indicating
how the cylinder, which is closed in the spinal cord, might be completed in
this region of the medulla oblongata by the union of the opposite margins.
Crossing the grey matter in the floor of the fourth ventricle several
transverse white lines, or stride, are usually observed, passing outwards from
the median fissure, and round the sides of the restiform bodies. Some of
these white strise form part of the roots of the auditory nerves, a few run
slantingly upwards and outwards on the floor of the ventricle, whilst others
again embrace the corresponding half of the medulla oblongata. These
transverse lines are sometimes wanting, in which case the white fibres on
which they depend probably exist at some depth below the surface.
Santorini, and subsequently Kolando, described a set of superficial white fibres on
the fore part and sides of the medulla oblongata, crossing over it below the olivary
bodies, fibrce vel processus arciformes. They belong to a system of white fibres which
pass transversely or horizontally outwards, and are probably continuous with the
septal fibres about to be noticed. Sometimes the greater part of the pyramidal and
olivary bodies is covered by a thin stratum of these transverse fibres, which appear to
issue from the anterior median fissure ; but, most commonly, these superficial fibres
are found only at the lower extremity of the olive, as the arciform fibres already
mentioned.
Besides the superficial transverse fibres now referred to, the medulla oblongata
presents other horizontal fibres in its interior, some of them disposed in a mesial
raphe or septum, and numerous others proceeding from that septum transversely
outwards. Of these last, the majority, passing through the olivary bodies, and in part
the pyramids, enter the corpus dentatum and form the whole of its white substance ;
and these fibres, then passing radiately through the grey capsule, turn backwards to
the fasciculus cuneatus and lateralis, those of them which pierce the anterior wall of
the capsule arching round it to reach their destination. Other fibres pass behind the
olivary into the restiform bodies, and seem to terminate in the grey substance of the
floor of the fourth ventricle. (See Kolliker's Handbuch der Gewebelehre, 1863,
p. 316.)
A small band of fibres is represented by Eeichert as passing obliquely downwards
and backwards from the side of the pons Varolii, descending between the auditory
and facial nerves, and crossing over the upper end of the posterior pyramids. He
names it the ala pontis. It probably is part of the ligula. (Keichert, Bau des
Menschl. Gehirns, part 1st, plate I., 1859.)
518
THE MEDULLA OBLONGATA.
Course of fibres from the spinal cord upwards through the medulla
oblongata. — Assuming, for convenience of description, the existence of three
white columns of the cord, these are disposed as follows.
1. The posterior column, with the exception of the fasciculus gracilis, is
distinguished by the name of processus cuneatus and enters into the forma-
tion of the restifonn body, which ascends to the cerebellum. The fasciculus
gracilis ascends to the cerebrum.
2. The lateral column ascends towards the base of the olivary body, and
is disposed of in three ways ; (1,) some of its fibres from the surface and
deep part join the restiform body and proceed with it to the cerebellum ;
(2,) a larger number, passing obliquely inwards, then come forwards between
the anterior columns, and crossing the median plane appear as the fibres of
decussation, and form the chief part of the opposite anterior pyramid ; (3,)
the remaining fibres pass up to the cerebrum, as the fasciculi teretes
Fig. 351. Fig. 351. — DIAGRAMMATIC REPRESENTA-
TION OP THE PASSAGE OF THE COLUMNS
OP THE MEDULLA OBLONGATA UPWARDS
AND DOWNWARDS.
A, the specimen, which, is seen from
before, includes the medulla oblongata and
the pons Varolii, with a small portion of
the spinal marrow. The left lateral column
(that to the reader's right) has been lifted
out of its place to the side, and the ante-
rior and posterior columns of that side
remain undisturbed : the right anterior and
posterior columns have been removed, and
the lateral column remains in its place.
The upper part of the right pyramid is
removed. The transverse fibres of the pons
Varolii have been divided in circumscribed
portions to different depths corresponding
with the several places of passage of the
columns of the medulla.
P, pons Varolii, part of the anterior sur-
face, where it has been left entire ; p, the
right and left pyramids, the upper part of
the right has been cut away ; p', the fibres
of the left pyramid as they ascend through
the poris exposed by the removal of the
superficial transverse fibres ; p'', placed on
the deeper transverse fibres of the pons on the right side, close below the divided fibres
of the pyramid ; a, left anterior column of the cord, passing upwards into the undecus-
sated part of the anterior pyramid, and into a', the olivary column ; 0, olivary body ;
o', the continuation of the olivary column ascending deeply through the pons, and
exposed by the removal of a small portion of the deeper transverse fibres; o", the
same fibres divided by a deeper incision on the right side ; I, the right lateral column,
passing upwards into the following parts, viz., x, the deeper part passing by decussation
into the left pyramid ; r, the part passing into the restiform body ; ft, the part ascending
in the back of the fourth ventricle as fasciculus teres ; to the outer side of this are seen
the ascending fibres of the posterior pyramid ; I', the left lateral column drawn aside
from its place in the spinal cord ; the fasciculus teres, ft, and the part to the restiform
body, r, cut short ; x , the deeper part passing by decussation into the right pyramid ;
r', the part of the restiform body derived from the anterior column of the spinal cord ;
pc, the posterior column of the left side exposed by the removal of the lateral column,
and shown ascending to the restiform body as fasciculus cuneatus, fc : on the right side
the posterior column being removed, fc, points to this fasciculus cuneatus cut short
below.
B, explanatory outline of the section of the spinal cord, a, anterior columns ; p,
posterior; I, lateral.
MINUTE STRUCTURE OF THE MEDULLA OBLOXGATA. 519
(faisceaux innomine's), appearing on the back of the pons Varolii, in the
upper part of the floor of the fourth ventricle.
3. The anterior columns having reached the apex of the anterior pyramids,
are thrust aside from their median position by the decussating fibres derived
from the lateral columns, and are then distributed in three divisions. (1,) A
very small division, ascends obliquely backwards beneath the olive, and joins
the restiform body (Solly). (2,) Another division passes directly upwards,
its fibres embracing the olivary nucleus, above which they are again collected
together, and are joined by other fibres arising from the nucleus, so as to
form the olivary fasciculus ; this ascends through the pons and at the side
of the cerebral peduncle under the name of the fillet, and reaches the corpora
quadrigemina and the cerebral hemispheres. (3,) The remaining division of
the anterior column ascends into the anterior pyramid, forming its outer
part. The anterior pyramids therefore are composed of fibres from the
lateral and anterior columns, and are continued up through the pons into
the peduncles of the cerebrum.
It is to be remembered, however, that the separation between these
different tracts of white fibres cannot be clearly followed out through the
whole structure of the medulla oblongata, but that they are more or less
blended with one another.
Grey matter of the medulla oblongata followed upwards from the cord. — The
central canal of the spinal cord, together with the grey matter which surrounds it,
approaches nearer and nearer to the back of the medulla oblongata as it ascends, until
it terminates in the calamus scriptorius.
The anterior pyramids are free from grey matter in their interior, and are separated
from the rest of the medulla by strong septa of connective tissue, and from one
another by a raplie, which extends back to the grey matter surrounding the central
canal, and which contains mesial horizontal fibres, named septal. The posterior
cornua of grey matter in the lower part of the medulla oblongata extend transversely
outwards from the central canal, and higher up stretch outwards and forwards to the
surface. The substantia gelatinosa is swollen out into a mass which appears circular
in a transverse section, and is named the grey tubercle of Rolando. The anterior
cornua, together with the intermedio-lateral tract, which had re-appeared at the upper
end of the cord, vanish in the form of elongated radiating streaks ; and between them
and the anterior pyramids appear the olivary nuclei, unconnected with the system of
grey matter prolonged from the spinal cord. Behind the posterior cornua two new
cornua make their appearance — one extending into the processus cuneatus and the
other into the posterior pyramid, and both of them increasing in size as the posterior
pyramids increase. In the neighbourhood from which these and the posterior cornua
spring there is seen in transverse sections a limited bundle of white fibres, the round
fascicle of Stilling. In the upper part of the medulla oblongata the grey matter is
principally spread out on the floor of the fourth ventricle. (Reichert, op. cit., part
2nd, plates I. and II.)
According to the observations of Stilling, part of the grey matter at the back
of the medulla forms special deposits or nuclei, which are connected with the roots
of the spinal accessory vagus, glosso-pharyngeal, and hypoglossal nerves. Of these
nuclei, the first or lowest is concealed in the substance of the medulla; whilst
those which are situated higher up gradually appear in the floor of the fourth
ventricle as small angular eminences pointing downwards, near the apex of the calamus
scriptorius. The first nucleus proceeding from below is that for the spinal accessory
nerve. It reaches some way down in the cord, and is there lost in the intermedio-
lateral tract. Above this nucleus, and close to the middle of the medulla, is another,
the second, commencing higher up, and connected with the hypoglossal nerve, the
roots of which, coming forward between the anterior pyramid and the olivary body,
appear at the surface in the depression between those parts. Continuing to ascend,
these two nuclei reach the back of the medulla, and then make their appearance in
the floor of the fourth ventricle. Higher up, the nucleus for the spinal accessory
520
THE MEDULLA OBLONGATA.
Fig. 352.
nerve is succeeded by a third in the same line, which is connected with the nervus
vagus, and is also placed to the outer side of that for the hypoglossus. Further out,
a fourth nucleus begins to be observed, belonging to the glosso-pharyngeal nerve.
The last change in the arrangement of these small grey masses consists in the gradual
narrowing of the nucleus of the par va-
gum, and the approximation of those for
the hypoglossal and glosso-pharyngeal
nerves which were previously separated
by it.
Fig. 352. — MAGNIFIED VIEWS OF TRANS-
VERSE SECTIONS OF THE MEDULLA OB-
LONGATA (after Lockhart Clarke, and
Reichert). f
These figures are to be looked upon as in
part diagrammatic, no attempt having been
made to represent the natural difference of
colour in the parts. For the most part,
however, the grey substance is'indicated by
the smoother dark shading, and the white
substance by distinct lines.
A, represents a section made at the
lower part of the decussation of the pyra-
mids; B, one immediately below the
olivary bodies ; C, one a very short dis-
tance below the calamus scriptorius ; and
D, a section in the lower part of the fourth
ventricle. The references are the following
in all the four figures : —
p, anterior pyramids ; p', their decussa-
tion ; 0, olivary bodies ; 0', the radiating
fibres proceeding from their interior; r,
restiform bodies and their nucleus ; pp,
posterior pyramids ; R, raphe ; c, central
canal and substance surrounding it ; tr,
grey tubercle of Rolando ; /, anterior
median fissure ; fpt posterior median
fissure ; a, arciform fibres ; I, lateral
column ; Z', larger cells and vesicular tract
of the lateral column ; CI a, anterior roots
of the first cervical nerve ; CI p, posterior
roots ; XII, hypoglossal nerve-roots issuing
at the side of the pyramid ; XII', its
nucleus ; XI, XI', spinal accessory nerve
and its nucleus ; VIII', nucleus of the
auditory nerve according to Reichert.
In A and B, the decussation of the pyra-
mids is represented ; in A, the anterior
and posterior cornua of the grey matter
still exist as in the spinal cord ; in B, the
anterior cornua are much diminished in
size, the posterior have begun to pass
outwards, and to be converted into the
grey tubercles, and the intermediate nuclei
to make their appearance between them ;
in C, the central canal is wider and ap-
proaches the posterior aspect, and the
olivary body appears between the anterior
pyramid and the lateral column ; in D, the
canal is opened up in the fourth ventricle,
and the various grey nuclei are for the
most part in the vicinity of its floor.
C.
a-
Langenbeck and Forg maintain that the pail regarded by Stilling as the nucleus
TEE PONS VAROLII. 521
for the glosso-pharyngeal nerve is really the place of origin of the greater root of the
fifth or trigeminal nerve.
Fig. 353. — TRANSVERSE SECTION Fig. 353.
OF THE MEDULLA OBLONGATA
(after Stilling). ±
The section is made at the level
of the middle of the olivary bodies];
the effect produced by transmitted
light is brought out on the left-
hand side of the figure, the half
to the right being only sketched,
a, anterior, and p, posterior
fissure ; b, anterior pyramid ; c,
olivary body with its corpus
dentatum shown internally ; d,
grey tubercle of Rolando in the
lateral column ; e, the restiform
body and its nucleus ; /, nucleus
of the roots of the glosso-pharyn-
geal nerve ; g, nucleus of the pneumo-gastric nerve ; h, that of the hypoglossal nerve ;
z, the septum or raphe ; 8, roots of the pneumo-gastric nerve emerging ; 9, roots of the
hypoglossal nerve.
THE PONS VAROLII AND CEREBELLUM.
THE PONS VAROLII or tuber annulare (mesocephalon of Chaussier, nodus
encepliali of B-au and Sommerring), forms an eminence of transverse fibres
above and in front of the medulla oblongata, below and behind the crura
cerebri, and between the lateral lobes of the cerebellum. Its margins are
arched ; the superior much more so than the inferior : thus, at the sides its
transverse fibres are much more gathered together, and form at the place
where it passes into the cerebellum a narrower bundle, which is named the
middle cms of the cerebellum. In the middle line the pons presents a
shallow groove in which the basilar artery lies, and is perforated by small
branches of that artery.
Although the superficial fibres are transverse in their general direction,
they are not all parallel to each other. The middle fibres pass directly
across, the lower set ascend slightly, whilst the superior fibres, which are the
most curved, descend obliquely to reach the crura cerebelli on each side ;
and there are also one or more superficial bands of the superior fibres
which cross obliquely downwards over the middle and lower fibres, and
completely conceal them at the sides.
In its internal structure the pons consists of the longitudinal or peduncular
fibres prolonged upwards from the medulla oblongata, of its own transverse
or conimissural fibres, through which the longitudinal fibres pass, and of a
large intermixture of grey matter. Behind the superficial transverse fibres
are seen the prolonged fibres of the anterior pyramids, which, as they ascend
through the pons, are widely separated into smaller bundles, intersected by
other transverse white fibres, which, with those upon the surface, are all
continued into the cerebellum.
The alternation of transverse and longitudinal fibres just described extends
to a considerable depth in the pons, the quantity of transverse fibres greatly
preponderating ; posteriorly there succeeds a third layer, consisting entirely
of longitudinal fibres, and comprehending the olivary fasciculi, and the
fasciculi teretes.
The median septum or raphe, which exists in the medulla oblongata, is
M M
522 THE CEREBELLUM.
prolonged throughout the whole height of the pons in its back part, but
becomes indistinct in approaching the front or basilar surface, except towards
its upper and lower edge, where the superficial fibres of the pons are mani-
festly continuous in the median line with these septal fibres. Bundles of
white fibres, belonging to the same system, encircle the crura cerebri at
their emergence from the upper border of the pons.
According to Foville, a few fibres from each of the three principal longitudinal
elements of the medulla turn forwards and become continuous with the transverse
fibres of the pons ; and, in like manner, one or more small bundles from each of the
crura cerebri take a similar transverse course. (Foville, op. cit., pi. II., figs. 2 and 3 ;
pi. III., figs. 5 and 6.)
THE CEREBELLUM, hinder brain, consists of a body and of three pairs of
crura or peduncles, by which it is connected with the rest of the eucephalon.
These crura are named superior, middle, and inferior.
Fig. 354. Fig. 354. — OUTLINE OP THE UPPER
SURFACE OF THE CEREBELLUM. £
At the upper part of the figure, the
crura cerebri and parts behind them
have been cut through and left in con-
nection with the cerebellum.
Ill, the third pair of nerves lying
upon the crura cerebri ; c r, white
matter or crust of the crura cerebri ;
In, locus niger ; t, tegmentum contain-
ing grey matter in the upper part of
the crura ; a s, aqueduct of Sylvius ;
q, corpora quadrigemina, the upper
elevations divided ; s v, superior ver-
miform process or central folia of the
middle lobe of the cerebellum ; I q,
lobulus quadratus ; p s, posterior supe-
rior lobe; fh, horizontal fissure ; pi,
posterior inferior lobe; n, the notch
between the hemispheres.
The superior peduncles, crura ad cerebrum or processus ad testes, together
with the valve of Vieusseus, a lamina stretched between them, connect the
cerebellum with the cerebrum.
The inferior peduncles, crura ad medullam, are the upper extremities of
the restiform bodies.
The middle peduncles, or crura ad pontem, much the largest, are the
lateral extremities of the transverse fibres of the pons Varolii. They
connect together the two halves of the cerebellum inferiorly.
All these peduncles consist of white fibres only ; and they pass into the
interior of the cerebellum at its fore part.
The cerebellum is covered with grey cortical substance, rather darker
than that of the cerebrum. Its greatest diameter is transverse, and
extends to about three and a half or four inches : its width from before
backwards is about two or two and a half inches ; and its greatest depth
is about two inches, but it is much thinner round its outer border.
It consists of two lateral hemispheres joined together by a median portion
called the vermiform process, which in the human subject is distinguishable
only as a small though well-marked part below, named the inferior vermiform
process, and a mere elevation above, called the superior vermiform process.
In birds, and in animals lower in the scale, this middle part of the cerebellum
FORM OF THE CEREBELLUM. 523
alone exists ; and in most mammals it forms a central lobe very distinct from
the lateral portions.
The hemispheres are separated behind by a deep notch. Superiorly, the
median portion or upper vermiform process, though slightly elevated, is not
marked off from the hemispheres, so that the general surface of the organ,
which is here inclined and flattened on each side, is uninterrupted. Below,
the hemispheres are convex, and are separated by a deep fossa, named the
vallecula, which is continuous with the notch behind, and in which the
inferior vermiform process lies concealed in a great measure by the sur-
rounding parts. Into this hollow the medulla oblongata is received in front,
and the falx cerebelli behind.
Fig. 355. — INFERIOR SURFACE OF THE CEREBELLUM WITH THE PONS VAROLII AND
MEDULLA OBLONQATA (from Sappey after Hirschfeld and Leveille.) f
1, placed in the notch between the cerebellar hemispheres, is below the inferior
vermiform process ; 2, 2, median depression or vallecula ; 3, 3, 3, the biventral, slender,
and posterior inferior lobules of the hemisphere ; 4, the amygdala ; 5, flocculus or sub-
peduncular lobule ; 6, pons Varolii ; 7, its median groove ; 8, middle peduncle of the
cerebellum ; 9, medulla oblongata ; 10, 11, anterior part of the great horizontal fissure ;
12, 13, smaller and greater roots of the fifth pair of nerves; 14, sixth pair; 15, facial
nerve; 16, pars intermedia; 17, auditory nerve; 18, glosso-pharyngeal ; 19, pneuino-
gastric ; 20, spinal accessory; 21, hypoglossal nerve.
The cerebellum, at the surface and for some depth, consists of numerous
nearly parallel laminse or folia, which are composed of grey and white
matter, and might be compared with the gyri of the cerebrum, but are
smaller and without convolution. These laminae are separated by slightly -
curved grooves or sulci of different depths.
One principal fissure, or sulcus, named the great horizontal fissure, divides
the cerebellum into an upper and a lower portion. It begins in front at the
entrance of the middle peduncles, and passes horizontally backwards round
the outer border of the hemispheres. From this primary fissure, numerous
others proceed on both the upper and under surfaces, forming nearly parallel
curves, having their concavities turned forwards, and separating the folia from
each other. All these furrows do not go entirely round the hemisphere, for
many of them coalesce with one another ; and some of the smaller furrows
have even an oblique course between the others. Moreover, on opening the
M M 2
624 THE CEREBELLUM.
larger fissures, many of the folia are seen to lie concealed within them, and
do not reach the surface of the cerebellum.
Certain fissures, which are deeper than the rest, and constant in their
position, have been described as separating the cerebellum into lobes, which
are named as follows.
The central lobe, situated on the upper surface, consists of about eight
folia, immediately adjoining the anterior concave border. The superior and
anterior lobe, sometimes called quadrate, and the superior and posterior lobe,
are placed between the central lobe and the great horizontal fissure. On the
under surface are seen successively the inferior posterior lobe, the slender
lobe, the biventral lobe, the amygdala, and the subpeduncular lobe or flocculus.
This last-named lobule, lobule of the pneumo-gastric nerve (Vicq-d'Azyr),
subpeduncular lobe (Gordon), or flocculus, projects behind and below the
middle peduncle of the cerebellum. It is connected by a slender pedicle of
white fibres to the rest of the hemisphere ; but its exposed surface is grey,
and is subdivided into five or six small laminae.
Fig. 356.
Fig. 356. — INFERIOR SURFACE OP THE CEREBELLUM WITH THE POSTERIOR MEDULLARY
VELUM (after Reil and Reichert, and from nature). f
The medulla oblongata has been in great part removed by a cut passing through it
near the pons Varolii ; the two amygdaloid lobules have also been removed, and the
medulla and pons Varolii pulled downwards in order to bring into view the posterior
medullary velum.
p s, posterior superior lobe of the cerebellum ; fh, horizontal fissure ; p i, posterior
inferior lobe ; g, lobulus gracilis ; b i, biventral lobe ; c, placed on the folia which pass
across between the hemispheres of opposite sides ; p, pyramid ; u, uvula ; n, placed in
the fourth ventricle immediately below the nodule ; p v, on each side, placed on the cut
surface where the amygdalae have been removed, points by a line to the posterior medullary
velum ; v, v, cavity of the fourth ventricle within the borders of the velum and behind
the inferior cerebellar peduncles; the cavity extends on each side into the pedicle of the
flocculus, /; m, section of the medulla oblongata, in which the posterior opening of the
olivary capsules of grey matter is shown ; VI, sixth nerves ; V, roots of the fifth nerves,
and above them, the facial and auditory roots.
Within the vallecula, or on its borders, the following parts are seen.
Commencing from behind, a conical and laminated projection named the
pyramid, is first met with. In front of that is another smaller projection,
called the uvula, which is placed between the two rounded lobes at the sides of
the vallecula, named the amygdala ; these terms having been suggested by
a comparison with the parts so named in the throat. Between the uvula
and amygdalse on each side, but concealed from view, is extended a ridge
CENTRAL LOBE.— FOURTH VENTRICLE.
525
of grey matter' indented on the surface, and named the furrowed band.
Still further forward is the anterior pointed termination of the inferior
vermiform process, named the nodule, which projects into the fourth ven-
tricle, and has been named the laminated tubercle (Malacarne). On each
side of the nodule is a thin white lamella of a semilunar form, which is
attached by its posterior convex border, and is free and concave in front.
The outer ends of these lamellss are attached to the flocculi, and the inner
ends to the nodule, and to each other in front of that projection. The two
lamellae together constitute the posterior medullary velum, which has been
compared with the valve of Vieussens, — the one being attached to the
superior extremity and the other to the inferior extremity of the middle
or vermiform portion of the cerebellum. This posterior velum is covered in
and concealed by the amygdalae, and cannot be properly seen until those
lobules have been turned aside or removed.
The fourth ventricle. — The space left between the medulla oblongata in
front and the cerebellum behind, is named the fourth ventricle, or ventricle
of the cerebellum.
Fig. 357.— VIEW OP THE Fig. 357.
FLOOR OP THE FOURTH VEN-
TRICLE WITH THE POSTERIOR
SURFACE OF THE MEDULLA
OBLONGATA AND NEIGH-
BOURING PARTS (from Sappey
after Hirschfeld and Le-
veille).
On the left side the three
cerebellar peduncles have been
cut short ; on the right side
the white substance of the
cerebellum has been preserved
in connection with the supe-
rior and inferior peduncles,
while the middle one has been
cut short.
1, median groove of the
fourth ventricle with the fas-
ciculi teretes, one on each
side; 2, the same groove at
the place where the white
striae of the acoustic nerve
emerge from it to cross the
floor of the ventricle ; 3, inferior peduncle or restiform body ; 4, posterior pyramid ;
above this the calamus scriptoriua ; 5, superior peduncle or processus a cerebello ad
cerebrum ; on the right side the dissection shows the superior and inferior peduncles
crossing each other as they pass into the white stem of the cerebellum j 6, fillet to the
side of the crura cerebri ; 7, lateral grooves of the crura cerebri ; 8, corpora quadri-
gemina.
The cavity of this ventricle is of a flat rhomboidal shape, being contracted
above and below, and widest across its middle part. The anterior extremity
of the inferior vermiform process projects into it from behind, and higher
up it is covered by the Vieussenian valve. It is bounded laterally by the
superior peduncles, and by the line of union of the medulla oblongata and
the cerebellum. The upper end of the ventricle is continuous with the
Sylvian aqueduct or passage (iter) leading up to the third ventricle.
The anterior surface or floor of the fourth ventricle is formed by the back
of the medulla oblongata and pons Varolii. It is shaped like a lozenge,
526 THE CEREBELLUM.
truncated at its upper part. Below, it is bounded by the diverging posterior
pyramids and restiform bodies surmounted by the ligula. It has already
been sufficiently described in connection with the medulla oblongata.
The lining membrane of the ventricle is continuous with that of the
ventricles in the interior of the cerebrum, through the aqueduct of Sylvius,
in which situation it is marked by delicate rugse, oblique or longitudinal in
direction. At the sides it is reflected from the medulla to the cerebellum,
and extends for a considerable distance outwards between the flocculus and
the seventh and eighth nerves. At the lower end of the ventricle, there is,
as was ascertained by Magendie, a narrow orifice in the membrane by which
the cavity communicates with the subarachnoid space.
Projecting into the fourth ventricle at each side, and passing from the
point of the inferior vermiform process outwards and upwards to the outer
border of the restiform bodies, are two small vascular processes, which have
been named the choroid plexuses of the fourth ventricle.
Fig. 358. Fig. 358. — OUTLINE SKETCH OP A VER-
TICAL SECTION OF THE CEREBELLUM TO
SHOW THE CORPUS DENTATUM IN ITS
MEDULLARY STEM. §
The section has been carried through the
left lateral part of the pons so as to divide
the superior peduncle and pass nearly
through the middle of the left cerebellar
hemisphere. The olivary body has also
been divided longitudinally so as to expose
in section its corpus dentatum.
cr, crus cerebri ; /, fillet ; q, corpora
quadrigemina ; sp, superior peduncle of
the cerebellum divided; m p, middle
peduncle or lateral part of the pons Varolii, with fibres passing from it into the white
stem ; av, continuation of the white stem radiating towards the arbor vitse of the folia ;
cd, corpus dentatum ; o, olivary body with its corpus dentatum; p, anterior pyramid.
Internal structure of the cerebellum. — The central part is composed of
white matter, which sends out spreading and gradually thinning layers into
the interior of all the laminse, larger and smaller, of the grey substance
which form a continuous covering on the surface. In consequence of this
arrangement of the white and grey substances, sections of the cerebellum
crossing the laminae, and dividing the grey and white substance together,
present a beautifully foliated or arborescent appearance, named arbor vitce.
This appearance is seen in any vertical section, but it is most perfect in that
which passes through the median plane, where the relative quantity of the
central white matter is small. The foliations are arranged somewhat pin-
nately, the section of each primary lamina having those of secondary laminse
clustered round it like leaflets 011 a stalk.
In the lateral hemispheres, where the peduncles enter, the white matter
is more abundant ; and, if a section be made through either hemisphere half
way between its centre and the middle of the vermiform process, it will
display a nucleus of grey matter, which is named the corpus dentatum of the
cerebellum. This structure, very similar to that already described in the
olivary body of the medulla oblongata, presents the appearance of a
waved line of compact yellowish brown matter, surrounded by white sub-
stance and containing whitish matter within. This line is interrupted at
INTERNAL STRUCTURE OF CEREBELLUM. 527
its upper and inner part. In whatever direction the section is carried
through the corpus dentatum, this waved line is seen, so that the dentate
body may be described as consisting of a plicated pouch or capsule of grey
substance open at one part and inclosing white matter in its interior,
like the corpus dentatum of the olivary body. White fibres may be traced
from it to the superior peduncles of the cerebellum and to the valve of
Vieussens.
Fig. 359. — VIEW OF A DISSECTION
OF THE FIBRES OF THE MEDULLA
OB LONG AT A AND PoNS VAROLII
(from Arnold). £
6, the anterior pyramid ; &', its
fibres traced upwards through, the
pons Varolii ; c, olivary column ; d,
olivary body ; m, superficial trans-
verse fibres of the pons on its left
side ; m', the deeper transverse
fibres of the right side; m", the
prolongation of these fibres as mid-
dle peduncle of the cerebellum ;
p, q, their continuation into the
laminse and folia of the cerebellum ;
n, inferior peduncle; x, the decus-
sating part of the left lateral
column crossing to the right ante-
rior pyramid.
The fibres in the primary lamelke can be traced continuously from the peduncles of
the cerebellum. Upon these central plates are laid other collateral lamellae, which
are not connected with the fibres proceeding from the middle of the cerebellum, but
merely pass from one folium to another.
The grey matter is not uniform throughout its whole thickness, but is composed of
two or more layers differing in colour and other characters ; — resembling, in this
respect, the cortical substance of the posterior convolutions of the cerebrum.
The fibres composing the peduncles of the cerebellum are arranged in its interior
in the following manner. The middle peduncles, which are the most superficial, enter
the lateral parts of the cerebellum ; they may be traced into the folia of those parts,
and form a large share of each hemisphere. The inferior peduncles pass upwards
into the middle part of the cerebellum, in the folia of which they are distributed,
especially in those of the upper surface. The superior peduncles, which are placed
nearest to the middle line, are principally connected with the folia of the inferior
vermiform process ; but a considerable number of them pass into or issue from the
grey capsule of the corpus dentatum which has been already described.
A very different account from, that which has generally been received of the course
and relations of the tracts of nervous substance of the cerebellum has recently been
put forward by Luys, and deserves mention in this place. According to the statement
of this author, all the fibres of the cerebellar peduncles arise from the interior of the
corpora dentata ; the cells of those centres receive externally fibres from the laminated
periphery of the cerebellum, and internally give origin to the peduncular fibres ; the
fibres of the inferior peduncles of opposite sides cross the middle line and terminate
in the interior of the olivary nuclei ; and the fibres of the superior peduncles, likewise
decussating in the mesial plane before quitting the cerebellum, terminate in a grey
centre in the interior of the tegmentum of the crus cerebri, named by Luys the
superior olivary body. He further alleges that different fibres pass in all directions
from the superior and inferior olivary bodies, and that thus the fibres of the cerebellum
form a separate system indirectly connected Avith the fibres of the rest of the cerebro-
spinal axis. Only a short notice, however, of these views having as yet been published,
it will be necessary that the observations on which they are founded be made known
and fully corroborated, before statements of so startling a nature can be generally
accepted. (Luys, in Journ. de 1'Anat. et de Physiol., 1864, p. 225.)
528
THE CEREBELLUM.
Microscopic Structure. — The cortical grey matter which covers the foliated surface
of the cerebellum is made up of the following elements, viz. : 1. Pellucid cells of
considerable size. 2. Cells, for the most part of large size, and caudate, having the
usual granular contents. These cells are embedded in a finely granular matrix ; the
greater number of those of the caudate kind have a pyriform shape, and are prolonged
Fig. 360. Fig. 360. — THE COLUMNS OP THE
MEDULLA OBLONGATA TRACED
UPWARDS INTO THE CEREBELLUM
AND CEREBRUM (from Arnold). |
a, part of the anterior column
which ascends in the olivary column ;
6, decussating portion of the lateral
column forming the pyramid and
turned down ; c, olivary fasciculus
ascending deeply through the pons ;
d, olivary body ; e, restiform body;
/, g, corpora quadrigemina ; c, h, i,
the fillet ; h, the part which asoends
to the cerebral peduncle ; i, the
part passing up to the corpora
quadrigemina ; m, m,', the trans-
verse fibres of the pons divided ; n,
inferior peduncle of the cerebellum ;
o, septal fibres of the medulla oblongata ; q, fibres of the inferior peduncle continued
into the laminse of the cerebellum ; ?•, r, superior peduncle ; t, fasciculus teres ; ut
thalamus ; v, corpus albicans.
Fig. 361. Fig. 361. — MINUTE STRUC-
TURE OP THE SUBSTANCE
OP THE CEREBELLUM (from
Kolliker).
A, large cells from the
grey cortical substance of the
human cerebellum. ~
a, three large cells exhibit-
ing granular contents and a
nucleus ; 6, the internal pro-
cesses seen in two of the
cells ; c, d, two external pro-
cesses running towards the
surface from two of the cells,
in the third cell one large
process only is seen; c', d',
ramified finer parts of these
processes.
B, course of the nerve-
tubes at the surface of the
cerebellum, magnified with a
low power.
a, nerve of the medullary
substance ; 6, nervus plexus
of the substantia ferruginea ;
c, border of that substance ;
d, fine fibres running out
from the dark -bordered tubes
into the superficial grey sub-
stance.
at their small end into a simple or branched appendage, and this process, as first
remarked by Purkinje, is in most of them directed towards the surface of the
cerebellum. 3. Small bodies, like cell-nuclei densely aggregated without any inter-
vening substance. These lie at some depth from the surface; according to Todd,
MINUTE STRUCTURE OF CEREBELLUM.— THE CEREBRUM. 529
they form a thin light-coloured lamina, intermediate between two darker strata of
grey matter which contain the nerve-cells ; one of these grey strata being the deepest
and next the white matter of the cerebellum, while the other, which is the darker
coloured of the two, is in contact with the pia mater. 4. Fibres. Tubular nerve-
fibres pass from the white into the grey matter, and extend through it nearly as far
as the surface. The mode of their termination, which is difficult to trace, has been
investigated by various anatomists. According to Valentin, they form loops and
return upon their course, but this statement has not been confirmed by other
observers.
Gerlach has recently described a very remarkable arrangement of the fibres of the
cerebellum. According to him, these fibres, on approaching the grey matter, split
up into extremely fine divisions, which form a network, while the granules, which he
considers as small cells with ramifying processes, are placed at the angles of the
meshes, and branching processes of the large nerve-cells also terminate in the network.
According to Kb'lliker, networks of tubular fibres exist within the grey matter and
communicate with the nerve-cells, while the granules belong to the reticulum of
connective tissue. Luys, like Gerlach, describes lateral processes as being given oft'
by the nerve-fibres to connect them with the granules, at the same time that they
terminate likewise directly, although much attenuated, in the large nerve-cells.
(Gerlach, "Microscopische Studien," pi. I., fig. 3; copied in Yirchow's "Cellular
Pathology/' by Chance, p. 269.)
THE CEREBRUM.
The cerebrum, or brain proper, constitutes the highest and much the
largest portion of the encephalon. It consists of the following parts, viz.,
the peduncular masses of the crura cerebri and processus a cerebello ad
cerebrum ; the series of eminences or cerebral centres or ganglia concealed
from view, named corpora quadrigemiua, optic thalami and corpora striata ;
the cerebral hemispheres, which are by far the most bulky part of the cere-
brum and of the whole encephalon, and form nearly the whole superficial
part ; various commissural structures including the corpus callosum and
fornix; and lastly some smaller structures, viz., the pineal and the pituitary
bodies, and the olfactory bulbs.
EXTERIOR OF THE CEREBRUM.
The cerebral hemispheres together form an ovoid mass, flattened on its
under side, and placed in the cranium with its smaller end forwards, its
greatest width being opposite to the parietal eminences. They are separated
in the greater part of their extent by the great longitudinal fissure.
Each cerebral hemisphere has an outer or convex surface, which is in
contact with the vault of the cranium ; an inner or flat surface, of a crescent
shape, which forms one side of the longitudinal fissure ; and an irregular
under surface, which rests on the base of the skull, and on the tentorium
cerebelli.
Three lobes, or large divisions, projecting in three different directions, have
usually been distinguished in each hemisphere, under the names of anterior,
middle, and posterior lobes. The division between the anterior and middle
lobes is very clearly denned below and on the sides by a deep cleft, named
the Sylvian fissure. There is no similar demarcation between the middle
and posterior lobes ; but anatomists have generally considered as the pos-
terior lobe that part of the hemisphere which lies over the cerebellum.
The under surface of the anterior lobe is triangular and excavated to adapt
it to the roof of the orbit on which it rests. The middle lobe is rounded
530
THE CEREBRUM.
and prominent, and occupies the middle fossa of the skull — the edge of the
lesser wing of the sphenoid bone corresponding with the Sylvian fissure.
Fig. 362. — UPPER SUR-
FACE OF THE BRAIN
SHOWING THE CONVO-
LUTIONS (from R. Wag-
ner). 4
This view was taken
from the brain of a
famous mathematician,
Professor C. F. Gauss,
who died in 1854, aged
78. It is selected as
an example of a well-
formed brain of the
usual size with fully
developed convolutions.
a, superior or first
frontal convolution ; a',
second or middle frontal ;
«", third or inferior
frontal ; A, A, anterior
ascending parietal con-
volution ; B, B, pos-
terior ascending parietal
convolution ; b, first or
upper parietal convolu-
tion ; b', second or mid-
dle ; b", third or in-
ferior ; c, first or upper
tempoi'al convolution ;
d, first or upper occipi-
tal convolution ; d',
second or middle ; d",
third or lower ; I, I, the
superior longitudinal fis-
sure ; r, the fissure of Rolando ; p, the external perpendicular fissure.
The posterior lobe is smooth and slightly concave on its under surface,
where it rests on the arch of the tentorium.
It is right to remark that some anatomical writers have admitted only two lobes,
reckoning the middle and posterior lobes as one, under the name of the posterior
lobe ; while others more recently have divided the middle lobe into two, an upper
and lower, and have added that of the island of Reil, so as to make five principal
lobes in all. These have been named respectively the frontal, parietal, temporal,
occipital, and central lobes.
The great longitudinal fissure, seen upon the upper surface of the brain,
extends from before backwards throughout its whole length in the median
plane, and thus separates the cerebrum, as already stated, into a right and
left hemisphere. On opening this fissure, it is seen, both before and behind,
to pass quite through to the base of the cerebrum : but in the middle it is
interrupted by a large transverse mass of white substance, named the
corpus callosum, which connects the two hemispheres together. While the
brain is in its natural situation, this fissure is occupied by a vertical process
of the dura mater — the falx cerebri — which dips down between the two
hemispheres, not quite reaching to the corpus callosum.
The Sylvian fissure, which separates the anterior and middle lobes, passes
at first upwards and backwards in the outer part of the hemisphere, and
FORM AND DIVISIONS OF THE CEREBRUM. 531
divides into two branches, anterior and posterior. It lodges the trunk and
primary divisions of the middle cerebral artery, and at its commencement
presents a spot pierced by numerous small arterial branches, and thence
named the locus perforatus anticus.
The surface of the hemispheres is composed of grey matter, and is moulded
into numerous smooth and tortuous eminences, named convolutions, or gyri,
which are marked off from each other by deep furrows, called sulci, or
anfractuosities.
Fig. 3G3.
Fig. 363.— LATERAL VIEW OF THE RIGHT CEREBRAL HEMISPHERE (from Sappey
after Foville). £
1, fissure of Rolando ; 2, anterior ascending parietal convolution ; 3, frontal convolu-
tions connected posteriorly with the anterior ascending parietal ; 4, union of two frontal
convolutions ; 5, posterior ascending parietal convolution ; 6, another parietal convolution
similarly Connected with those on the inner surface ; 7, 7, anterior part of the convolu-
tion of the fissure of Sylvius; 8, 8, horizontal part of the same convolution; 9, 9,
posterior part ; 10, 11, 12, anterior, middle, and posterior principal convolutions of the
island of Reil or central lobe ; 13, supraorbital convolution ; 14, part of the temporal
lobe ; 15, occipital lobe.
CEREBRAL CONVOLUTIONS. — The convolutions are covered closely through-
out by the vascular investing membrane, the pia mater, which sends pro-
cesses down to the bottom of the sulci between them, while the serous
covering, the arachnoid membrane, passes from one convolution to another,
over their summits and without dipping between them. The sulci are
generally from half an inch to an inch in depth ; but in this respect there
is much variety in different brains, and in different parts of the same brain ;
those upon the outer convex surface of the hemisphere being the deepest.
In general, the depth of a convolution exceeds its thickness ; and its thick-
ness, near the summit, is somewhat greater than through its base.
Since the external grey or cortical substance is continuous over the whole
surface of the cerebral hemispheres, being found alike within the sulci and
upon the gyri, a far greater extent of grey matter is thus exposed to the
vascular surface of the pia mater with a given size of the brain, than could
have been the case had the hemispheres been plain and destitute of
convolutions.
The general arrangement of the convolutions has been made the subject
532 THE CEREBRUM.
of study by various anatomists in earlier and recent times, but still re-
quires farther elucidation. An attempt to describe minutely all the indi-
vidual gyri would be difficult and useless, owing to their irregularity in
different cases, and their want of symmetry in the same brain. .Nevertheless,
there are some sufficiently constant in presence, and characteristic in situa-
tion and form, to admit of being specially described ; and it seems probable
that, by a sufficiently careful comparison of the convolutions in different
animals, and the observation of their development in the foetus, certain
general facts may be ascertained regarding them, tending to throw light
upon their disposition in man.
Fig. 364.
Fig. 364. — OUTLINE OP THE CHREBRUM AS SEEN FROM THE LEFT SIDE, SHOWING THE
CONVOLUTIONS AS DISTINGUISHED BI GRATIOLET. f
F, frontal lobe ; P, parietal lobe ; T, temporal lobe ; 0, occipital lobe ; R, R, fissure
of Rolando ; s, s. fissure of Sylvius, posterior division : s', s', its anterior division ; C, at
the junction of the two, marks the place of the central lobe or convolutions of the island
of Reil ; p, the place of the vertical or occipital fissure ; «, a', a", superior, middle and
inferior frontal convolutions ; a*, supraorbital convolutions ; A, anterior transverse or
ascending parietal convolution ; B, posterior transverse or ascending parietal convolution ;
&, &', b", upper, middle and lower parietal convolutions ; c, c', c", upper, middle and
lower temporal convolutions; d, d', d", upper, middle and lower occipital convolutions ;
between b, b', b", and d, d'} d", are seen the connecting convolutions ; between c and c',
the parallel fissure.
The island of Reil constitutes the set of convolutions (gyri operti) which
appear earliest both in the fostus and in the animal series, It is a
triangular eminence, broken externally into short radiating convolutions,
which forms a delta between the anterior and posterior division of the
fissure of Sylvius, and is limited externally by a deep sulcus. This mass,
constituting the central lobe of recent authors, derives additional interest
from being the centre round which the principal convolutions of the cere-
brum are arranged. It is only brought into view by laying open the fissure
of Sylvius. (See Figs. 368 and 377.)
The convolution of the Sylvian fissure is a very large convolution, which is
also early in its appearance in animals. Commencing in front of the inner
end of the Sylvian fissure, it takes a tortuous and much folded course all
round that fissure, giving off numerous secondary gyri, and terminates behind
the fissure opposite the point where it began.
The gyrus fornicatus, convolution of the corpus callosum, or internal con-
CEREBRAL CONVOLUTIONS. 633
volution, is one of the most distinct and symmetrical convolutions in the
whole brain. Commencing on the under surface of the brain, immediately
before the anterior perforated space, it ascends a short distance in front of
the anterior recurved extremity of the corpus callosum, and then runs back-
wards immediately above that body, as far as its posterior extremity : there
it turns downwards and forwards, embracing the cerebral peduncle, to reach
the entrance of the Sylvian fissure. This long convolution, therefore, describes
a sort of arch or ring, open or interrupted opposite the Sylvian fissure, and
embracing the corpus callosum above, and the cerebral peduncle below. It
thus, as was pointed out by Foville, forms a sort of rim or border to the
grey matter ; whence it is named by him convolution d'ourlet. The surface
of this convolution, especially towards its inferior termination, is covered by
a very thin cribriform layer of white substance, which, with the grey matter
beneath, gives the surface a mottled aspect. This has been called the reti-
culated white substance.
The marginal convolution of the longitudinal fissure is a large convolution
which may be traced, more or less indented or interrupted however in its
course, along the line of junction between the convex and flat surfaces of
the hemisphere, forming the lip of the great longitudinal fissure. Ifc com-
mences on the under surface of the brain, in common with the gyrus
fornicatus, and, passing forwards, forms the inner border of the triangular
orbital surface of the anterior lobe. In this part it is cleft longitudinally
by a deep sulcus, into which the olfactory bulb is received, and which, it may
be mentioned, is developed at an earlier period than the convolution itself.
On the front and upper surface of the cerebrum, this convolution may
generally be traced for some distance along the margin of the longitudinal
fissure, but soon becomes marked by deep sulci ; and, thus interrupted, may
be followed round the posterior extremity, and along the under surface of
the hemisphere forwards as far as the point of the middle lobe, running
parallel for some space with the under portion of the gyrus fornicatus. Two
of the sulci which interrupt the marginal convolution are very constant,
viz., the vertical fissure with the fissure of the hippocampi, and the fissure
of Rolando.
The fissure of the hippocampi has a deep origin in the inner margin of the
middle lobe of the brain between the fascia dentata and the gyrus fornicatus,
and, passing backwards, crosses that gyrus on the under surface of the brain,
behind the corpus callosum, and proceeds in a nearly horizontal course along
the inner face of the hemisphere. This fissure is important as forming the
reverse of the elevations of the hippocampi in the interior of the brain, and
as being (according to Reichert) produced at an early period in connection
with the general development of the hemispheres, and being comparable
therefore rather to the fissure of Sylvius than to a mere sulcus. The part
of the gyrus fornicatus beneath this fissure is distinguished as the gyrus
hippocampi.
The fissure of Rolando, starting from behind the vertex, runs outwards and
forwards from the longitudinal fissure, so that the right and left grooves
form a V-shaped line open in front. It derives its importance from being
characteristic of the form of the brain of man and the quadrumana, and
separating two considerable convolutions, which extend from the superior
longitudinal fissure to the fissure of Sylvius. These convolutions, peculiar
to the greater number of simise and attaining their fullest development in
man, constitute the anterior and posterior transverse or anterior and
posterior ascending parietal convolutions.
634 THE CEREBRUM.
The vertical fissure of recent authors crosses the marginal convolution in the
posterior part of the cerebrum, extending slightly outwards upon its upper surface
and more deeply on its internal aspect, so as to form a separation between the
so-called parietal and occipital lobes.
According to Foville the convolutions may be arranged in four principal orders,
founded in a great measure on their relative connections with the anterior perforated
space, which, in his estimation, is a part of the highest importance.
The first order issues from the perforated space, and consists of two portions. One,
large and vertical, is the gyrus fornicatus, without its ascending secondary gyri ; the
other, short and horizontal, is the slightly elevated ridge which bounds the perforated
space in front and on the outer side.
Fig. 365. — RIGHT HALF OE THE BRAIN DIVIDED BY A VERTICAL ANTERO -POSTERIOR
SECTION (from various sources and from nature), i
1, great superior or marginal convolution ; 2, convolution of the corpus callosum ; 3,
secondary convolutions running between this and the preceding ; within the numbers
2, 2, 2, the corpus callosum ; 4, the fifth ventricle ; 5, the third ventricle (see Fig. 377
for a larger view of these parts) ; 5', pituitary body; 6, immediately behind the corpora
quadrigemina and pineal gland; +, the fourth ventricle; 7, pons Varolii ; 8, medulla
oblongata ; 9, cerebellum ; the middle lobe showing the section of the arbor vitse ; I, the
olfactory bulb ; II, the right optic nerve ; the commissure cut through ; III, the right
nerve of the third pair.
The second order, also consisting of two portions, commences from the horizontal
portion of the first order on the limits of the perforated space. One part corresponds
with the marginal convolution of the longitudinal fissure, as already described, except
that part of it on the orbital surface of the anterior lobe which lies to the outer side
of the olfactory sulcus ; the other part is the convolution of the Sylvian fissure.
The third order consists of two sets, of which one occupies the inner surface of the
hemisphere, and connects the gyrus fornicatus in its whole length with the marginal
convolution of the longitudinal fissure ; the other set lies in the Sylvian fissure, forms
the island of Reil, and connects the short horizontal portion of the first order with
the convolution surrounding that fissure.
The convolutions of the fourth order, the largest, deepest, and least symmetrical of
all, are quite detached from the perforated space, and have no relation to the first
order of convolutions. They connect the two convolutions of the second order
CEREKRAL CONVOLUTIONS.
635
together, viz., the marginal convolution of the median fissure and that of the Sylvian
fissure, and occupy the outer or convex surface of the cerebral hemisphere.
Leuret, by an extended comparison of the brains of different animals, was led to
divide mammals into fourteen groups, according to the disposition of the convolutions.
In the lowest or simplest group, including the bat, mole, and rat, the Sylvian
fissure is the only division of the surface present, or along with it a few very slight
sulci. In a higher group, containing the fox and dog, and presenting in a marked
form the t}rpical mode of division, Leuret recognises as fundamental six convolutions
— four external, including the superior marginal and that of the fissure of Sylvius,
and two internal, viz., the supraorbital and gyrus fornicatus. In other groups,
together with various other modifications of form by subdivision or by union through
supplemental ones, the number of the fundamental convolutions is frequently reduced
to five or to four.
In the brain of the elephant, on the other hand, placed by Leuret in the thirteenth
group, he recognises the superior transverse convolutions; and in the last group,
comprehending the quadrumana, these transverse convolutions are two in number,
and are separated by the groove, named by Leuret fissure of Rolando. These trans-
verse or ascending parietal convolutions are a constant and well-marked feature of the
human bi'ain, in which they attain their highest development.
Fi-. 366.
Fig. 366. — OUTLINE OP THE INNER SURFACE OP THE EIGHT HALF OP THE BRAIN,
SHOWING THE PRINCIPAL LOBES AND CONVOLUTIONS ACCORDING TO GrRATIOLET.
F, frontal lobe ; P, parietal ; 0, occipital ; T, temporal ; r, fissure of Rolando ; /,
fronto-parietal fissure ; p', inner perpendicular or occipito -parietal fissure ; h, the calca-
rine fissure of Huxley, and with the line continued forwards between g and h', the hippo-
campal fissure ; ti, convolution of the hippocampus ; g, gyrus fornicatus or convolution
of the corpus callosum ; s, Sylvian fissure ; I, olfactory bulb ; II, optic nerve ; III, third
nerve; C, cerebellum.
More recently, Gratiolet has arranged the convolutions with great detail, according
to their most distinguishing common features in man and the simiae. On the
external surface of the hemisphere he distinguishes five lobes, viz., the frontal and
parietal above the fissure of Sylvius ; the temporo-splienoidal below that fissure ; the
occipital behind it, and the island of Reil, or central lobe, within the fissure. The
frontal lobe he divides into an orbital and a frontal portion, and in the frontal portion
536 THE CEREBRUM.
he distinguishes a superior, middle, and inferior tier of convolutions. In the parietal
lobe are the anterior and posterior ascending convolutions (convolution of Rolando)
surrounding the fissure of Rolando, and behind these a curved lobe. In the temporo-
sphenoidal lobe are described a superior, middle, and inferior convolutions, lying
parallel to the fissure of Sylvius. The occipital lobe presents also three tiers, but less
distinct than those of the frontal, and besides these are four convolutions uniting the
occipital and parietal lobes, named by Gratiolet plis de passage, or the connecting
convolutions.
The internal surface^ of the hemisphere Gratiolet divides into the fronto-parietal
lobe, corresponding in extent to the frontal and parietal lobes of the external surface,
and limited behind by the internal perpendicular fissure, the occipital lobe between
that fissure and the fissure of the hippocampi; and the occipito-temporal lobe,
including the tentorial surface, and extending outwards to the sphenoido-temporal
lobe.
It is to be remarked, however, that the divisions and nomenclature of Gratiolet,
however useful they may be for the purpose of explicit comparison of the convolu-
tions of the human brain with those of the quadrumana, the study in which the
inventor has made use of them, are yet of a somewhat artificial description, and may
not be applicable to a more extended comparison of the disposition of the convolu-
tions among animals.
From Reichert's plates it is apparent that the internal perpendicular fissure (occi-
pito-parietal of Huxley) is the upper of two branches into which the fissure of the
hippocampi divides posteriorly in its first development, and which together with
that fissure constitutes his fissura occipitalis. The inferior branch, the posterior
part of the fissure of the hippocampi, is the calcarine fissure of Huxley.
Not only the comparison of the brain of man with those of other animals, but like-
wise the comparison of human brains one with another, establishes the existence of a
relation between mental development and the complication, size, and depth of the
cerebral convolutions, and the extent of the grey matter contained in them.
On the subject of the cerebral convolutions the reader may consult, in addition to
the works of Arnold, Tiedemann, Foville and Reichert, that of Leuret and Gratiolet
"Anat. Comp. du Systeme Nerveux, 1839-57;" Gratiolet, "Mem. sur les Plis
C6re"braux de 1'Homme et des Primates, 1854 ; " R. Wagner, " Tiber die typischen
Verschiedenh. der Windungen der Hemispharen," &c., Getting. 1860-62 ; Huschke,
" Schadel, Hirn und Seele," 1854 ; Huxley, " Brain of Ateles paniscus," Proc. of
Zool. Soc., June, 1861 ; J. Marshall, (( On the Brain of a Bush-woman, and on the
Brains of Two Idiots, &c.," Trans. Roy. Soc. 1863.
BASE or THE CEREBRUM. — When the brain is turned with its base upper-
most, and the parts of which it is composed are allowed to fall slightly
asunder by their own weight, two considerable masses, consisting of white
substance externally, are seen emerging together from the fore part of the
poiis Yarolii, and, separating from each other as they proceed forwards and
outwards, to enter the inner and under part of the right and left cerebral
hemispheres. These white masses, which are marked on the surface with
longitudinal striae, and have somewhat the appearance of large bundles of
fibres, are the peduncles or crura of the cerebrum. Immediately before
entering the corresponding hemisphere, each is crossed by a flattened white
cord, named the optic tract, which, adhering by its upper border to the
peduncle, is directed forwards and inwards, and meets in front with its
fellow of the opposite side to form the optic commissure, from the fore part
of which the optic nerves proceed.
Limited behind by these diverging peduncles, and in front by the con-
verging optic tracts, is a lozenge-shaped interval, called the interpeduncular
space, in which are found, in series from behind forwards, the posterior per-
forated space, the corpora albicantia, and the tuber cinereum, from which
is prolonged the infundibulum attached to the pituitary body.
The posterior perforated space (locus perforatus posterior) is a deep fossa
PARTS IX THE IXTERPEDUXCULAR SPACE. 537
situated between the peduncles, the bottom of which is composed of greyish
matter, connecting the diverging crura together, and named pons Tarini.
It is perforated by numerous small openings for the passage of blood-vessels ;
and some horizontal white striae usually pass out of the grey matter and turn
round the peduncles immediately above the pons.
Fig. 367.
Fig. 367. — BASE OP THE BRAIN WITH THE ORIGINS OP THE CEREBRAL NERVES. ^
This figure is taken from an adult male brain which had been hardened in alcohol.
1, superior longitudinal fissure ; 2, fissure of the olfactory tract and lower part of the
superior convolution ; 2', orbital convolutions; 2", external or inferior frontal convolu-
tion ; 3, inner part of the fissure of Sylvius, near the anterior perforated spot ; 3, 3, outer
part; 4, inner convolution of the temporal lobe; 4', middle convolution; 4", outer con-
volution; 5, 5', occipital lobe; 6, on the right pyramidal body of the medulla oblongata
above the decussation ; 7, amygdaloid lobe of the cerebellum ; 8, biventral lobe ; 9,
lobulus gracilis ; 10, posterior inferior lobe ; +, the inferior vermiform process; I,
olfactory bulb ; I', the tract divided on the left side, showing the three white striai by
which it is connected with the brain ; II, in the anterior perforated spot, marks the right
optic nerve; the left has been cut short; III, on. the right crus cerebri, denotes the third
pair ; IV, on the inner convolution of the middle lobe, the fourth pair ; V, the trige-
minus; VI, on the pons Varolii, the sixth ; VII, also on the pons Varolii, the seventh ;
VIII, on the left lobe of the cerebellum below the horizontal fissure and the flocculus,
denotes the eighth pair; IX, on the upper part of the right amygdaloid lobe, denotes
the ninth pair ; X, on the same, the suboccipital nerve.
The corpora albicantia or mammillaria are two round white eminences in
front of this fossa, each about the size of a small pea, surrounded by grey
matter, and connected together across the middle line.
The corpora albicantia are formed, as will hereafter be explained, by the anterior
extremities of the fornix ; hence they have also been named bulbs of thefornix. In
538
THE CEREBRUM.
the foetus they are at first blended together, and they become separated about the
beginning of the seventh month. In most vertebrate animals there is but one white
eminence or corpus albicans in their place.
Fig. S68. Fig. 368.— VIEW FROM
BEFORE OF THE ME-
DULLA OBLONGATA,
PONS VAROLII, CRURA
CEREBRI, AND OTHER
CFNTRAL PORTIONS OF
THE ENCEPHALON.
On the right side the
convolutions of the cen-
tral lobe or island of Eeil
have been left, together
with a small part of the
anterior cerebral convolu-
tions : on the left side
these have been removed
by an incision carried
betweon the thalamus
opticus and the cerebral
hemisphere.
I', the olfactory tract
cut short and lying in its
groove between two con-
volutions ; II, the left
optic nerve in front of
the commissure^; II', the
right optic tract ; Th,
the cut surface of the left
thalamus opticus ; C, the
central lobe or island of
Reil ; Sy, fissure of
Sylvius ; x x , locus
pevforatus anterior ; e,
the external, and i, the
internal corpus genicu-
latum ; h, the hypophysis
cerebri or pituitary body ;
tc, tuber cinereum with
the infundibulum ; a, one
of the corpora albicantia ;
P, the cerebral peduncle
or crus ; /, the fillet ;
III, close to the left
oculo-motor neive ; x,
the locus perforates pos-
ticus; PV, pons Varolii ;
V, the greater root of the fifth nerve ; +, the lesser or motor root ; on the right side
this + is placed on the Gasserian ganglion, arid points to the lesser root, where it proceeds
to join the inferior maxillary nerve ; 1, ophthalmic division of the fifth nerve ; 2, superior
maxillary division ; 3, inferior maxillary division ; VI, the sixth nerve ; VII a, the
facial ; VII b, the auditory nerve; VIII, the pneumo-gastric nerve ; Villa, the glosso-
pharyngeal ; VIII b, the spinal accessory nerve ; IX, the hypoglossal nerve ; fl, the floc-
culus ; fh, the horizontal fissure of the cerebellum (Ce) ; am, the amygdala; pa, the
anterior pyramid ; 0, the olivary body ; r, the restiform body ; d, the anterior median
fissure of the spinal cord, above which the decussation of the pyramids is represented ;
ca, the anterior column ; cl, the lateral column of the spinal cord ; C I, the suboccipital
or first cervical nerve.
The tuber cinereum is a lamina of grey matter extending forwards from
the corpora albicantia to the optic commissure, to which it is attached, and
forming, as afterwards described, part of the floor of the third ventricle.
ca
PARTS SEEX IX THE BASE OF THE CEREBRUM. 539
In the middle it is prolonged into a hollow conical process, the infundi-
bulum, to the extremity of which is fixed the pituitary body.
The pituitary body or hypophysis cerebri, formerly called pituitary gland,
from its being erroneously supposed to discharge pituita ii,to the nostrils, is
a small reddish grey mass, of a somewhat flattened oval shape, widest in the
transverse direction, and occupying the sella turcica of the sphenoid bone.
It consists of two lobes, of which the anterior is larger, and concave behind,
where it embraces the smaller posterior lobe. Its weight is from five to ten
grains. In the adult it is solid, and of a firm consistence.
The anterior lobe consists of two kinds of matter, one hard and grey, the
other, situated within, softer and of a yellowish white colour. The posterior
lobe is darker and redder than the anterior. Both are very vascular.
The pituitary body appears to approach in structure to the vascular or duct"
less glands, such as the thyroid and suprarenal bodies, &c. According to Sharpey's
observations, with which those of subsequent writers agree, it differs greatly in
structure, at least in its anterior and larger lobe, from any other part of the ence-
phalon. The substance of the anterior lobe appears to be constituted by a mem-
branous tissue forming little round cavities or loculi, which are packed full of
nucleated cells. The loculi are formed of transparent, simple membrane, with a few
fibres and corpuscles resembling elongated cell-nuclei disposed round their walls.
The cells contained in the cavities are of various sizes and shapes, and not unlike
nerve-cells or ganglion-globules ; they are collected into round clusters, filling the
cavities, and are mixed with a semi-fluid granular substance. This thin granular
matter, together with the cells and little specks of a clear glairy substance like
mucus, can be squeezed from the cut surface, in the form of a thick, white, cream-like
fluid.
In the foetus, the pituitary body is proportionally large, and contains a cavity
which communicates, through that of the infundibulum, with the third ventricle.
This body is constantly present, and has the same connection with the brain in all
vertebrate animals.
In the middle line of the base of the brain, in front of the optic commis-
sure, is the anterior portion of the great longitudinal fissure, which passes
down between the hemispheres. At a short distance in front of the com-
missure, this fissure is crossed transversely by a white mass, which is the
anterior recurved extremity of the corpus callosum. On gently turning back
the optic commissure, a thin connecting layer of grey substance, the lamina
cinerea, is seen occupying the space between the corpus callosum and the
commissure, and continuous above the commissure with the tuber cinereum.
It is connected at the sides with the grey substance of the anterior perforated
space, and forms part of the anterior boundary of the third ventricle : it is
somewhat liable to be torn in removing the brain from the skull ; and, in
that case, an aperture would be made into the fore part of the third
ventricle.
At a short distance outwards from the lamina cinerea is the anterior per-
forated spot (locus perforatus anticus), a depression near the entrance of the
Sylvian fissure, floored with grey matter, and pierced with a multitude of
small holes for the passage of blood-vessels, most of which are destined for
the corpus striatum, — the deeper portion of the brain beneath which it lies.
The grey surface of each perforated space is crossed by a broad white
band, which may be traced from the middle of the under surface of the
corpus callosum in front, backwards and outwards along the side of the
lamina cinerea towards the entrance of the Sylvian fissure. These bands of
the two sides are named the peduncles of the corpus callosum.
When the entire encephalon is viewed from below, the back part of the
540
THE CEKEBRUM.
tinder surface of the cerebrum is concealed by the cerebellum and the pons
Varolii. If, however, these parts be removed, it will be seen that the tw o
hemispheres of the cerebrum are separated behind as they are in front, by
the descent of the great longitudinal fissure between them, and that this
fissure is arrested by a cross mass of white substance, forming the posterior
extremity of the corpus callosum. This posterior part of the great longi-
tudinal fissure is longer than the anterior portion.
INTERNAL PARTS OF THE CEREBRUM.
The anatomy of the interior of the cerebrum is most conveniently studied
by removing, after the manner of Vieussens and Vicq-d'Azyr, successive
portions of the hemispheres by horizontal sections, beginning from above.
Fig.
Ik
Fig. 369. — VIEW OP THE CORPUS CALLOSUM FROM ABOVE (from Sappey after Foville). ^
The upper surface of the corpus callosum has been fully exposed by separating the
cerebral hemispheres and throwing them to the side; the gyrus fornicatus has "been
detached, and the transverse fibres of the corpus callosum traced for some distance into
the cerebral medullary substance.
1, the upper surface of the corpus callosum ; 2, median furrow or raphe ; 3, longi-
tudinal strise bounding the furrow ; 4, swelling formed by the transverse bands as they
pass into the cerebrum ; 5, anterior extremity or knee of the corpus callosum ; 6, pos-
terior extremity ; 7, anterior, and 8, posterior part of the mass of fibres proceeding from
the corpus callosum ; 9, margin of the swelling ; 10, anterior part of the convolution of
the corpus callosum; 11, hem or band of union of this convolution; 12, internal con-
volutions of the parietal lobe; 13, upper surface of the cerebellum.
The first horizontal section, to be made about half an inch above the
corpus callosum, displays the internal white matter of each hemisphere,
speckled with red spots where its blood-vessels have been divided, and sur-
THE CORP (IS CALLOSUM. 541
rounded on all sides by the grey matter which is seen to follow closely
the convoluted surface, and to be of nearly equal thickness at all points.
This white central mass in each hemisphere was named by Vicq-d'Azyr
centrum ovale minus. On separating the remaining portions of the two
hemispheres from each other, two sulci are seen to exist between the corpus
callosurn and the gyri immediately in contact with it, viz., the gyrus
fornicatus of each side. These sulci were distinguished by the older anatomists
as ventricles of the coitus callosum.
Another section being made at the level of the corpus callosum, the
white substance of that part is seen to be continuous with the internal
medullary matter of both hemispheres : and the large white medullary mass
thus displayed, surrounded by the border of cortical substance, constitutes
what is generally described as the centrum ovale, of Vieussens.
The corpus callosum or great commissure (trabs cerebri) is a white struc-
ture, with a length not quite half of that of the brain, and approaching
about two-fifths nearer to the front than the back of the hemispheres. It
Fig. 370.
Fig. 370. — HORIZONTAL SECTION OP THE BRAIN SHOWING THE LATERAL VENTRICLES AND
THE FIFTH VENTRICLE OPENED (from Sappey after Vicq-d'Azyr). ^
1, the fifth, ventricle ; 2, the two laminse of the septum lucidum meeting in front of
it ; 3, lesser hippocampus of the posterior cornu ; 4, horizontal section of the posterior
swelling of the corpus callosum; 5, middle part of the fornix, where it has been separated
from the corpus callosum ; 6, posterior pillar of the fornix ; 7, hippocampus major
descending in the middle cornu ; 8, eminentia collateralis ; 9, lateral parts of the fornix ;
10, choroid plexus ; 11, tsenia semicircularis ; 12, corpus striatum.
is about an inch in width behind, and somewhat narrower in front. Its
thickness is greater at the ends than in the middle, and is greatest behind,
542
THE CEREBRUM.
•where it is nearly half an inch. It is arched from before backwards. Its
upper surface is distinctly marked by transverse furrows, which indicate
the direction of the greater number of its fibres. It is also marked in the
middle by a slight longitudinal groove, the raphe, which is bounded laterally
by two white tracts, placed close to each other, named striae longitudinales,
or nerves of Lancisi. On each side, near the margin, are seen other
longitudinal lines (striae longituclinales laterales) occasioned by a few scanty
white fibres.
In front, the corpus callosum is reflected downwards and backwards,
between the anterior lobes, forming a bend named the genu. The inferior
or reflected portion, which is named the rostrum, becomes gradually nar-
rower as it descends, and is connected by means of the lamina cinerea with
the optic commissure. It also gives off the two bands of white substance,
already noticed as the peduncles of the corpus callosum, which, diverging
from one another, run backwards across the anterior perforated space on
each side to the entrance of the Sylvian fissure.
Fig. 371.
semicircularis ; y, enrinentia collaterals.
Fig. 371. —THE LATERAL
VENTRICLES OPENED BY
A HORIZONTAL SECTION,
AND THE MIDDLE CORNU
EXPOSED ON THE RIGHT
SIDE. £
a, b, anterior and pos-
terior parts of the great
longitudinal fissure ; c,
section of the anterior part
of the corpus callosum ; d,
posterior part of the same ;
e, the left choroid plexus ;
/, the fornix ; g, the an-
terior; 7t, the posterior,
and q, the descending
cornu of the lateral ven-
tricle; k, Jc, corpora
striata ; I, I, optic tha-
larai ; n, n, right and left
hippocampus minor ; o,
posterior pillar of the for-
nix ; v, the corpus fimbri-
atura into which it passes;
<?, cornu ammonis or pes
hippocampi ; A, the medul-
lary substance of the cere-
bral hemisphere ; r, part
of the cortical substance
showing alternate grey and
white matter ; s, s, tsenia
Behind, the corpus callosum terminates in a free thickened border (bour-
relet, pad), the under surface of which is also free for a short distance
forwards.
The under surface of the corpus callosum is connected behind with the
fornix, a structure to be presently described, and in the rest of its length
with the septum lucidum, a vertical partition between the two lateral ven-
tricles.
THE LATERAL VENTRICLES. 543
Although it presents a few longitudinal white fibres on its surface, the corpus cal-
losum consists almost entirely of fibres having a transverse course towards each side,
and spreading in a radiating manner into the substance of the two hemispheres. As the
transverse fibres from the anterior and posterior lobes of the cerebrum are necessarily
aggregated in large numbers near the corresponding ends of the corpus callosum, its
greater thickness at those points, in comparison with the rest of its extent, is
accounted for ; and, since the posterior lobe reaches further beyond the corpus callosum
than the anterior, the greater thickness behind is also explained.
LATERAL VENTRICLES, or ventriculi tricornes. — By dividing the fibres of
the corpus callosum in a longitudinal direction at a short distance on each
side of the middle line, and about midway between the two ends of the
hemispheres, an opening is made into the right and left lateral ventricles of
the brain. These ventricles form part of the general ventricular space
within the cerebrum ; they are serous cavities, and are lined by a delicate
epitheliated structure, the ependyma ventriculorum, which at certain parts in
the adult, and probably throughout its whole extent in the foetus, is pro-
vided with cilia. In the natural state, the walls of the ventricles are moist-
ened internally with a serous fluid, which sometimes exists in considerable
quantity, even in a healthy brain.
It was formerly a subject of dispute whether the lining of the ventricles consisted
of epithelium only, or also of a membrane. The progress of the histology of the
brain has solved the problem in a manner which leaves the disputants on both sides
partially in the right. It is now recognised that a peculiar form of connective tissue is
found throughout the substance of the brain, similar to that which has been described
in the spinal cord. A layer of this substance, unmixed with nerve-tissues, but in direct
continuity with the interstitial web, and not a distinct membrane, supports the
epithelium. It is of the same nature as the substance immediately surrounding the
central canal of the spinal cord, and is named by Virchow neuroglia (Virchow's
" Cellular Pathology," by Chance, p. 273).
The form of the epithelial cells appears to vary in different parts ; these cells
being, according to Kb'lliker, of the flat pavement kind in the third ventricle, and
more spherical in the lateral ventricles ; and, according to Gerlach, cylindrical in the
aqueductus Sylvii.
From the central part or body of each lateral ventricle the cavity is
extended into each of the three lobes of the hemisphere, thus forming
an anterior, a posterior, and a middle or descending cornu.
The body of each lateral ventricle is roofed in by the corpus callosum, and
is separated from its fellow by a vertical partition, the septum lucidum,
which descends from the corpus callosum to the fornix. In the floor of the
ventricle there is seen most posteriorly one half of the fornix, which is a
thin layer of white brain-substance, broad behind and narrow in front :
external and anterior to this is the choroid plexus of the lateral ventricle, a
red vascular fringe, forming the border of the velum interpositum, a fold
of pia mater extending inwards, on which the fornix rests : external and
anterior to the choroid plexus is the anterior and outer part of the optic
thalamus, appearing from beneath it : outside and in front of the thalamus
is the corpus striatum ; and between those two bodies is a narrow flat band,
the tcpnia semicircularis.
The anterior cornu is the blind anterior extremity of the ventricle, pro-
jecting a little way into the anterior lobe. It is covered by the corpus
callosum, and turns forwards and outwards round the anterior free extremity
of the corpus striatum, descending as it proceeds, and bounded behind by
that body, and in front by the reflected part of the corpus callosum.
The middle or descending cornu turns round the back part of the optic
544
THE CEREBRUM.
thalamus, which appears in its cavity and forms its anterior boundary,
while its remaining boundaries are formed by the hemisphere. At its com-
mencement it is directed backwards and outwards ; then, passing downwards
with a sweep, it curves forwards, and at its extremity has a marked inclina-
tion inwards. The principal object seen upon the floor of this cornu is the
hippocampus major (pes hippocampi, or cornu ammonis), a large white
eminence extending the whole length of the cornu. The hippocampus
major becomes enlarged towards its anterior and lower extremity, and is
indented or notched on its edge, so as to present some resemblance to the
'paw of an animal, whence, no doubt, its name of pes hippocampi. The
white fibres of its surface are directed obliquely backwards and outwards
across it: they form only a thin smooth layer, and beneath them is cineritious
matter continuous with that of the surface of the hemisphere. Along the
inner edge of this eminence is seen a narrow white band, named corpus
fimbriatum or tcenia hippocampi, which is prolonged from the fornix ; to the
inner side of the tsenia is a part of the choroid plexus, and next to that the
back of the optic thalamus. This cornu differs from the others in respect
that it is not a mere cul-de-sac, but, by the mere separation of the mem-
branes, can be made to communicate in its whole length with the surface
of the brain by the fissure through which the choroid plexus enters.
Fig. 372.
Fig. 372. — A DEEP VIEW OP
THE LATERAL VENTRICLES
AND THEIR CoRNUA WITH THR
VELUM INTERPOSITUM. |
The fornix has heen divided
near its anterior pillars and
turned back, c, the anterior
part of the corpus callosum
divided; e, the lyra on the
lower surface of the corpus
callosum and fornix ; /, ante-
rior pillars of the fornix divided
(these are represented of too
large a size) ; g, anterior, and
7t, posterior cornu of the lateral
ventricle ; k, k, corpora striata;
£, pes hippocampi in the lower
part of the middle cornu ; r, rt
thalami optici ; s, «, tsenia se-
micircularis ; t, t, choroid
plexus ; v, velum interpositum;
a:, x, posterior pillars of the
fornix ; yt emiuentia collate-
ralis.
The posterior cornu pro-
jects backwards into the
substance of the posterior
lobe. At its extremity it
is pointed, and directed inwards. On the inner side of its floor is a curved
and pointed longitudinal eminence, named hippocampus minor, ergot, or
calcar avis ; and at the junction of the posterior with the descending cornu,
between the hippocampus major and minor, is a smooth eminence, named
eminentia collateralis, or pes accessorius.
The hippocampus minor is only the convex side of the fold which forms
the calcarine sulcus, and part of the sulcus of the hippocampi ; and in like
THE SEPTUM LUCIDUM.— THE FORXIX. 545
manner the eminentia collaterals corresponds with the posterior branch of
the fissure of Sylvius.
As some discussion has recently taken place in this country with regard to the
value of the presence of the hippocampus minor in man, as a distinctive character of
the human brain, it may be well to mention that this structure has been found even
in the brains of quadrumana which do not belong to the highest group. In the
human subject the posterior cornu varies greatly in size, and the hippocampus minor
is still more variable in its development, being sometimes scarcely to be recognised,
and at others proportionally large. It is usually most developed where the posterior
cornu is longest ; but length of the posterior cornu, and prominence of the hip-
pocampus minor, by no means occur in proportion to the dimensions of the hemi-
sphere, but rather seem to be associated with thinness of both the medullary and
the cortical substance.
The septum lucidum is a thin translucent partition, placed between the
two lateral ventricles. It extends vertically between the corpus callosum
above, and the anterior part of the fornix below ; and, as the latter sinks
down in front away from the corpus callosum, the septum is deep before
and narrow behind. Anteriorly it lies in the hollow of the bend of the
corpus callosum, in front of the fornix.
The septum lucidum is double, being composed of two distinct laminse,
having an interval between them, which contains fluid and is lined
by an epitheliated membrane. This is the fifth ventricle, ventricle of the
septum, or Sylvian ventricle.
Each of the laminse of the septum which form the sides of the fifth ven-
tricle, consists of an internal layer of white substance and an external layer
of grey matter.
In the human embryo, and also in some animals, the cavity of this ventricle com-
municates with that of the third ventricle in front and below : but in the adult human
brain it forms a separate and insulated cavity. Tarin described a small fissure in it
between the pillars of the fornix ; but this is unusual. In disease it is sometimes
distended with fluid.
The fornix is an arched sheet of white longitudinal fibres, which appears
partly in the floor of both lateral ventricles. It consists of two lateral
halves, which are separated from each other in front and behind, but
between those points are joined together in the mesial plane. The two
parts in front form the anterior pillars of the fornix ; the middle conjoined
part is named the body ; and the hind parts, which are again separated from
each other, form the posterior pillars.
The body of the fornix is triangular in shape, being broad and flattened
behind, where it is connected with the under surface of the corpus callosum,
and narrower in front as it dips down to leave that body, — the space
between them being filled up by the septum lucidum. Its lateral edges
are in contact with the choroid plexuses, and its under surface rests upon
the velum interpositum.
The anterior crura or pillars of the fornix, cylindrical in form, descend,
slightly apart from each other, through a quantity of grey matter on the
sides of the third ventricle, between the corpora striata ; and, curving back-
wards as they descend, reach the corpora albicantia. There each crus turns
upon itself, making a twisted loop which forms the white portion of the
corpus albicans of its own side, and ascends to enter the substance of the
optic thalamus. These crura are connected with the peduncles of the pineal
gland, and with the tsenia semicircularis, as will be afterwards described.
546
THE CEREBRUM.
Immediately behind the anterior pillars, where they descend, the fornix,
which further back rests upon the optic thalami, the velum interpositum
alone intervening, has an interval on each side left between it and the
groove where the optic thalamus and corpus striatum meet. This interval
leads from the lateral ventricle to the third ventricle — the space between the
thalami and beneath the velum interpositum. The openings of opposite
sides, passing downwards and backwards, meet in the middle line below,
and thus is produced a passage, single below, but dividing into two
branches above somewhat like the letter Y, and forming a communication
between the third ventricle and both lateral ventricles. This passage is
named the foramen of Monro, or foramen commune anterius.
Fig. 373.
Fig. 373, A. — LOWER AND BACK PART OF THE
CEREBRUM OP THE LEFT SIDE, SHOWING THE
POSTERIOR AND MIDDLE CORNUA OP THE
LATERAL VENTRICLE OPENED (altered from
Hirschfeld and Leveille). |
1, 1', inner convolution of the temporal lobe
turning round into the convolution of the gyrus
fornicatus, and showing on its surface the
reticulated structure; 2, cut surface of the
cerebral hemisphere ; 3, point of the posterior
cornu of the lateral ventricle ; 3', eminentia
collaterals ; 4, cut surface of the lower and
back part of the corpus callosum divided near
the middle ; 4', placed on the extension of the
corpus callosum into the cerebral hemisphere,
points by a line to the hippocampus minor in
the posterior cornu ; 5, cut edge of the posterior
pillar of the fornix passing down at 5', into
the hippocampus major and corpus fimbriatum ;
6, continuation of the corpus fimbriatum or
taenia hippocampi ; 6', pes hippocampi ; 7, fascia
dentata on the inside of the white substance of
the tfenia.
Fig. 373, B. — SECTION OP THE HIPPOCAMPUS
MAJOR TO snow THE ARRANGEMENT OP THE
GREY AND WHITE SUBSTANCE (from Mayo).
a, white layer on the surface of the hippo-
campus ; b, grey substance which is involuted
from the surface of the neighbouring convolution ;
c, fascia dentata ; d, white reticulated substance
of the lower part of the gyrus fornicatus;
e, cavity of the lateral ventricle.
The posterior crura or pillars of the
fornix are the diverging continuations
backwards of the two flat lateral bands
of which the body is composed. At
first they adhere to the under surface of the corpus callosum, then curving
outwards, each crus enters the descending cornu of the corresponding
lateral ventricle, and is prolonged as a narrow band of white matter, named
tcenia hippocampi or corpus fimbriatum, which is situated on the inner
margin of the hippocampus major, and extends to the extremity of that
structure.
On examining the under surface of the fornix and corpus callosum, there are
seen posteriorly the thickened border or pad, and in front of it the diverging
TRANSVERSE FISSURE OF THE CEREBRUM.
547
halves of the fornix, between which a triangular portion of the corpus
callosum appears, marked with transverse, longitudinal, and oblique lines.
To this part the term lyra has been applied.
The transverse fissure of the cerebrum is the passage by which the pia
mater passes from the surface into the ventricles of the brain to form the
choroid plexus. It may be laid open in its whole extent, after the lateral
ventricles have been opened, by completely dividing the fornix and corpus
callosum in the middle line, and raising the divided parts from the undis-
turbed velum interpositum below. It will then be found that, in like manner,
the posterior and middle lobes of the brain, including the hippocampus
major and corpus fimbriatum, may be raised from the subjacent parts as far
as the extremity of the descending cornu of the lateral ventricle. The
transverse fissure is, therefore, a fissure extending from the extremity of the
Fig. 374.
Fig. 374. — VIEW OP THE UPPER SURFACE OP THE VELUM INTERPOSITTJM, CHOROID PLEXTJS,
AND CORPORA STRIATA (from Sappey after Vicq-d'Azyr). f
1, fore part of the tela choroidea or velum interpositum ; 2, choroid plexus; 3, left
vein of Galen partly covered by the right ; 4, small veins from the front of the corpus
callosum and the septum lucidum ; 5, veins from the corpus striatum ; 6, convoluted
marginal vein of the choroid plexus ; 7, vein rising from the thalamus opticus and corpus
striatum ; 8, vein proceeding from the inferior cornu and hippocampus major ; 9, one
from the posterior cornu ; 10, anterior pillars of the fornix divided in front of the
foramen of Monro ; 11, fornix divided near its forepart and turned backwards ; 12, lyra;
13, posterior pillar united with, 14, the corpus callosum behind, and covered by the
choroid plexus as it descends into the inferior cornu.
548 THE CEREBRUM.
descending cornu on one side, over the constricted part of the cerebrum, to
the extremity of the descending cornu of the other side. It is bounded
above by the corpus callosum and fornix in the middle, and more externally
on each side by a free margin of the hemisphere : inferiorly it is bounded
near the middle line by the corpora quadrigemina, and on each side by the
cms cerebri and posterior part of the optic thalamus.
In the free margin of the hemisphere brought into view by opening out the
part of the transverse fissure which leads into the descending coruu of the
lateral ventricle, there are seen (1st) the ribbon-like ledge formed by the
corpus fiinbriatmn, internally to the hippocampus major ; (2nd) beneath
this, a small grey indented ridge, the fascia dentata ; and (3rd) beneath the
fascia dentata, the gyrus hippocampi. On making a transverse section, it is
seen that the corpus fimbriatum is the free margin of the white substance of
the hemisphere, and that the fascia dentata is the free margin of the cortical
substance, and is continuous with the grey matter of the hippocampus
major, and that thus the hippocampus major is the swelling in reverse of
the sulcus between the fascia dentata and gyrus hippocampi. The fascia
dentata can be traced up to the pad or bourrelet : its upper part is free of
dentations, and is sometimes named fasciola cinerea. The dentations cor-
respond with blood-vessels passing to and from the choroid plexus.
The velum interpositum or tela choroidea, the membrane which connects
the choroid plexuses of the two sides together, is a prolongation of the pia
mater through the transverse fissure. It corresponds in extent with the
fornix, which rests upon its upper surface ; and its more highly vascular
free borders, projecting into the lateral ventricles, form the choroid plexuses.
The choroid plexuses appear like two knotted fringes, reaching from
the foramen of Monro, where they meet together beneath the fornix, to the
point of each descending cornu. They consist of a highly vascular villous
membrane. The villi with which they are covered are again divided upon
their surfaces and at their borders into small processes, along which fine
vessels are seen to run, Numerous small vessels pass between the plexuses
and the surface of the corpora striata, as well as other neighbouring parts, and
the epithelium of the ventricles is continued over their surface. Thus it is
only at the foramen of Monro that the epithelial lining of the lateral ven-
tricles is continuous with that of the third ventricle.
The epithelium changes its character where it covers the plexus. It is there
composed of large spheroidal corpuscles, in each of which is seen, besides a distinct
nucleus, several yellowish granules, and one or more dark round oil-drops. According
to Henle each of these cells is provided with short, slender, acuminate, transparent,
and colourless processes.
On raising the velum interpositum, two slight vascular fringes are seen
running along its under surface, and diverging from each other behind.
They form the choroid plexuses of the third ventricle.
The choroid artery enters the velum mterpositum at the point of the
descending cornu ; and other arteries enter from behind, beneath the corpus
callosum. The greater number of the veins terminate in two principal
vessels named the veins of Galen, which run backwards on the velum mter-
positum, and passing out beneath the corpus callosum pour their blood into
the straight sinus, having generally first united into a single trunk.
Bichat supposed that the arachnoid membrane entered the third ventricle in the
form of a tubular process, which passed beneath the posterior end of the corpus
callosum and fornix, through the velum interpositum, and thus opened into the
PARTS SEEN IX THE LATERAL VENTRICLES.
549
upper and back part of the third ventricle.
canal of Bichat, is no longer admitted.
The existence of this canal, named the
The velum having been removed, the optic thalami are brought fully into
view, together with the cavity of the third ventricle situated between
them, while, behind the third ventricle, between it and the upper surface of
375.
Pig. 375. — DISSECTION OF THE BRAIN FROM ABOVE, EXPOSING THE LATERAL, THIRD AND
FOURTH VENTRICLES, WITH THE SURROUNDING PARTS (from Hirschfeld and Leveille). £
a, the anterior part or knee of the corpus callosum divided ; its fibres are seen spreading
on each side into the cerebral hemispheres ; b, anterior part of the surface of the right
corpus striatum in the anterior cornu of the lateral ventricle ; b', the same on the left
side, in which the grey substance has been dissected so as to show the peduncular medul-
lary fibres spi-eading through the corpus striatum into the cerebral hemisphere ; c, points
by a line to the tzenia semicircularis : d, surface of the thalamus opticus ; e, the anterior
pillars of the fornix divided; below they are seen descending in front of the third ven-
tricle, and between them is seen a part of the anterior commissure ; above the letter
is seen the fifth ventricle represented as a slit between the two laminae of the septum
lucidum ;_/", placed on the soft or middle commissure ; g, in the posterior part of the third
ventricle; on either side of this letter is the v/hite stria or peduncle of the pineal gland ;
immediately below the letter is the small posterior commissure and the pineal gland ; h,
the upper, and t, the lower of the corpora quadrigemina ; k, processus a cerebello ad
cerebrum ; and close to this the valve of Vieussens, which is partly divided by a median
incision along with the middle lobe of the cerebellum, so as to open up the fourth ven-
tricle ; I, the hippocampus major and corpus fimbriatum separated from the posterior
pillar of the fornix and descending into the middle cornu of the lateral ventricle ; m,
posterior cornu of the lateral ventricle and hippocampus minor ; n, eminentia collateralis ;
o, the cavity of the fourth ventricle ; p, posterior surface of the medulla oblongata ; r,
section of the middle lobe showing the arbor vitse ; s, upper surface of the cerebellum
brought into view on the left side by the removal of a considerable part of the posterior
cerebral lobe.
550 THE CEREBRUM.
the cerebellum, are seen the pineal body, the corpora quadrigemina, the
valve of Vieussens, and the processus a cerebello ad cerebrum.
The THIRD VENTRICLE is a narrow longitudinal cleft placed between the
optic thalami, which bound it on its two sides. It is covered above by the
velum interpositum and the fornix. Beneath, its floor is formed by the
following parts, which have been already described as seen on the base of
the cerebrum ; viz., commencing from behind, the posterior perforated space,
the corpora albicantia, the tuber ciuereum and infundibulum, and the
lamina cinerea, the last of which also serves to close it in front, as high as
the anterior commissure. Behind, is the anterior opening of the aqueduct
of Sylvius. The cavity is crossed by three commissures, named from their
position, anterior, middle, and posterior.
The middle or soft commissure is composed almost entirely of grey
matter, and connects the two thalami. It is variable in size, and some-
times wanting ; it is frequently torn across in examining the brain.
The anterior commissure is a round bundle of white fibres, placed imme-
diately in front of the anterior pillars of the fornix, and crossing between the
corpora striata. It marks the anterior boundary of the ventricle ; its fibres
extend laterally through the corpora striata, a long way into the substance
of the cerebral hemispheres..
The posterior commissure, also white but of smaller size, is placed across
the back part of the ventricle, immediately before and below the pineal
body, with which and with the corpora quadrigemina it is intimately
connected.
The corpora striata, situated in front and to the outer side of the optic
thalami, are two large ovoid masses of grey matter, the greater part of each of
which is embedded in the middle of the white substance of the hemisphere
of the brain, whilst a part comes to the surface in the body and
anterior cornu of the lateral ventricle. This intraventricular portion of
the corpus striatum is of a pyriform shape, its larger end being turned
forwards, and its narrow end being directed outwards and backwards, so
that the optic thalami of the two sides are received between the diverging
corpora striata. On cutting into it, there may be seen at some depth from
the surface white fibres, which are prolonged from the corresponding cerebral
peduncle, and give it the streaked appearance from which it has received its
name.
The extraventricular portion of the corpora striata will be afterwards
described.
Along the inner border of each corpus striatum, and in a depression
between it and the optic thalamus, is seen a narrow whitish semitrans-
parent band, named tcenia semicircularis, which continues backwards into
the descending cornu of the ventricle, where its connections have not been
determined with precision. In front it reaches the corresponding, anterior
pillar of the fornix, and descends in connection with that cord of white
substance.
It is more transparent and firm on the surface, especially at its fore part : and
this superficial stratum has been named stria cornea. The taenia consists of longi-
tudinal white fibres, the deepest of which, running between the corpus striatum and
the thalamus, were named by Vieussens centrum geminum semicircular e. Beneath
it are one or two large veins, which receive those from the surface of the corpus
Btriatum and end in the veins of the choroid plexuses.
The thalami optici (posterior ganglia of the brain) are of an oval shape,
THE THALAMI OPTICI.
551
and rest on the corresponding cerebral crura, which they in a manner
embrace. On the outer side each thalamus is bounded by the corpus
striatum and tsenia semicircularis. The upper surface, which is white, is
free and prominent, and is partly seen in the lateral ventricle, and partly
covered by the fornix. The part which is seen in the lateral ventricle is
more elevated than the rest, and is named the anterior tubercle. The
posterior surface, which is also white and free, projects into the descending
Fig. 376.
Fig.
376. — EIGHT HALF OF THE ENCEPHALIC PEDUNCLE AND CEREBELLUM AS
FKOJI THE INSIDE IN A MEDIAN SECTION (after Reichert).
II, right optic nerve ; II', optic commissure divided ; III, right third nerve ; VI,
sixth nerve ; V 3, third ventricle ; Th, hack part of the thalamus options ; H, section of
the pituitary body ; A. corpus albicans ; P, pineal gland ; c a, points by a lower line to
the anterior commissure divided, and by an upper line to the divided anterior pillar of
the fornix ; Ic, lamina cinerea ; i, infundibulum (cavity); tc, tuber cinereum ; /, mark
of the anterior pillar of the fornix descending in the wall of the third ventricle ; c m,
commissnra mollis ; sp, stria pinealis ; cp, posterior commissure, above it the peduncle
of the pineal gland, and below it the upper end of the passage to the fourth ventricle ;
Q, corpora quadrigemina (section); as, aqueduct of Sylvius near the fourth ventricle ;
P V, pons Varolii divided in the middle ; M, medulla oblongata ; p a, right anterior
pyramid; pel, decussating bands cut across ; pp, posterior pyramids; c, central canal
•with grey substance surrounding it divided. In the cerebellum, av, stem of white sub-
stance in the centre of the middle lobe of the cerebellum, ramifying towards the arbor
vitaa ; s v, superior vermiform process or vertical portion of the middle lobe ; s c, single
folium, which passes across between the posterior superior lobes; c', the folia, which
unite the posterior inferior lobes ; p, pyramid ; u, uvula ; n, nodule ; 1, part of the
laminae of the square lobe ; 2, posterior superior lobe ; 3, posterior inferior lobe ; 4, lob ul us
gracilis ; 5, bi ventral lobe ; 6, amygdaloid lobe.
cornu of the lateral ventricle. The inner sides of the two thalami are in
contact one with the other. They present the grey substance of the inte-
rior of the thalami uncovered with white, and are generally partially united
together by a transverse portion, which forms the middle or soft commissure
of the third ventricle.
552 THE CEREBRUM.
The pineal body or gland (conarium) is a small reddish body, which is
placed beneath the back part of the corpus callosum, and rests upon the
anterior elevations of the corpora quadrigemina. It is attached to the under
surface of the velum interpositum, so that it is liable to be torn away from
the brain in removing that membrane. It is about the size of a small
cherry-stone. Its base of attachment, which is its broader part, is directed
forwards, and is connected with the rest of the cerebrum by white substance.
This white substance is principally collected into two small rounded
bundles, named peduncles of the pineal gland, which pass forwards upon
the optic thalami along their upper and inner borders, and may be
traced as far as the anterior pillars of the fornix, in conjunction with which
they descend. These peduncles are connected with each other behind, and
the band of union between them is adherent to the back of the posterior
commissure.
This band is represented by Reichert as folding forwards and then backwards, so
as to leave a hollow, which he calls recessus pinealis, opening backwards above the
pineal body. Some anatomists have described two inferior peduncles, which descend
upon the inner surface of the thalami.
The pineal gland is very vascular. It is hollowed out into two or more
cells, which, sometimes at least, open anteriorly into the ventricle, and
almost always contain, besides a viscid fluid, a quantity of gritty matter,
named acervulus cerebri. This consists of microscopic round particles,
aggregated into small compound masses, which are again collected into
larger groups. It is composed of the so-called amylaceous or amyloid
bodies, and of earthy salts combined with animal matter, viz., phosphate
and carbonate of lime, with a little phosphate of magnesia and ammonia
(Stromeyer). It is found at all ages, frequently in young children, and
sometimes even in the foetus. It cannot, therefore, be regarded as the
product of disease.
This sabulous matter is frequently found on the outside of the pineal body, or
even deposited upon its peduncles. It is found also in the choroid plexuses ; and
scattered corpora amylacea occur in other parts of the membranes of the brain.
Huschke has pointed out that the pineal body is larger in the child and the female
than in the adult male. In the brains of other mammals it is proportionally larger
than in the human subject, and less loaded with the matter of acervulus cerebri.
The corpora or tubercular quadrigemina are four rounded eminences,
separated by a crucial depression, and placed two on each side of the middle
line, one before another. They are connected with the back of the optic
thalami, and with the cerebral peduncles at either side ; and they are
placed above the passage leading from the third to the fourth ventricle.
The upper or anterior tubercles are somewhat larger and darker in colour
than the posterior. In the adult, both pairs are solid, and are composed of
white substance on the surface, and of grey matter within.
They receive bands of white fibres from below, the majority of which are
derived from a fasciculus named the fillet. A white cord also passes up
on each side from the cerebellum to the corpora quadrigemina, and is
continued onwards to the thalami : these two white cords are the pro-
cessus a cerebello ad cerebrum, or superior peduncles of the cerebellum. At
each side of the corpora quadragemina there proceed outwards two white
bands, which pass to the thalami and to the commencements of the optic
tracts. These bands are prominent on the surface, and are sometimes named
brachia.
DEEP PARTS OF THE CEREBRUM. 553
In the human brain the quadrigeminal bodies are small in comparison
with those of animals. In ruoainant, soliped, aud rodent animals, the
Fig. 377.
To,
Fig. 377. — VIEW OP THE MEDULLA OBLONGATA, PONS VAROLII, CRURA CEREBRI, AND
CENTRAL PARTS OF THE ENCEPHALON FROM THE RIGHT SIDE.
The corpus striatum and thalamus opticus have been preserved in connection with the
central lobe and crura cerebri, while the remainder of the cerebrum has been removed.
St, upper surface of the corpus striatum ; Th, back part of the thalamus opticus ; G,
placed on the middle of the five or six convolutions constituting the central lobe or island
of Reil, the cerebral substance being removed from its circumference ; Sy, fissure of
Sylvius, from which these convolutions radiate, and in which are seen the white striae of
the olfactory tract ; I, the olfactory tract divided and hanging down from the groove in
the convolution which lodges it ; II, optic nerves a little way in front of the commissure ;
a, right corpus albicans with the tuber cinereum and infundibulum in front of it ; h,
hypophysis or pituitary body ; e, external, and i, internal corpus geniculatum at the back
part of the optic tract; P, peduncle or crus of the cerebrum ; /, fillet; III, right oculo-
motor nerve ; p, pineal gland ; q, corpora quadrigemina ; IV, trochlear nerve rising from
-y, the valve of Vieussens ; V, placed on the pons Varolii above the right nervus trige-
minus ; s, the superior, wi, the middle, aud in, the inferior peduncles of the crus cere-
belli cut short ; VI, the sixth nerve ; VII a, facial nerve ; VII b, auditory nerve ; on
the medulla oblongata the parts are indicated as follows : VIII, placed opposite to the
cut end of the pneumo-gastric nerve ; a, the glosso-pharyngeal ; and b, the uppermost
fibres of the spinal accessory nerve ; IX, the hypoglossal nerve ; p a, anterior pyramid ;
o, olivary body; a r, arciform fibres; p p, posterior pyramid; r, restiform body; tr,
eminence corresponding to the tubercle of Rolando ; at the commencement of the spinal
cord, ca, indicates the anterior, cp, the posterior, and cl, the lateral columns; C I,
anterior and posterior roots of the suboccipital or first cervical nerve.
o o
554 THE CEREBRUM.
anterior tubercles are much larger than the posterior, as may be seen in the
sheep, horse, and rabbit ; and hence the name nates, formerly applied to
the anterior, and tebtes to the posterior tubercles. In the brains of carnivora,
the posterior tubercles are rather the larger. In the foetus of man and
mammals these eminences are at first single on each side, and have
an internal cavity communicating with the ventricles. They are constant
in the brains of all vertebrate animals ; but in fishes, reptiles, and birds,
in which animals they receive the name of optic lobes, they are only two in
number, and hollow : in marsupialia and monotremata, they are also two in
number, but are solid.
Optic tracts and corpora, geidculata. — The optic tracts, which have already
been referred to in connection with the base of the cerebrum, are attached
to and embrace the under side of the corresponding peduncles, and
may be traced back to the thalami. Ench tract, somewhat cylindrical
towards the optic commissure, becomes flattened and broader as it approaches
the thalamus, and makes a bend as it turns round the peduncle to reach
the back part of that body. Near this bend, which is named the knee
(genu), and to the outer side of the corpora quadrigemina, are placed two
small oblong and flattened eminences connected with the posterior extremity
of the optic tract. They are two little masses of grey matter about the size
and shape of coffee-beans, placed one on the outer and one on the inner side
of the genu of the optic tract, and hence are named respectively corpus
geniculatum externum and internum. They send fibres into the optic tract
and also into the thalamns of the same side.
The fibres of the optic tracts are therefore derived from three sources,
viz. , the thalamus, the tubercula quadrigemina, and the corpora geniculata.
The processus a cerebello ad cerebrum are two large white cords extending
downwards and somewhat outwards from the corpora qnadrigemina to the
fore part of the cerebellum, and connecting the latter with the cerebrum.
They rest upon the crura cerebri, to which they are united, and between
them is the valve of Vieussens.
The valve of Vieussens (velum medullare anterius), stretched between the
processus a cerebello ad cerebrum, is a thin layer of nervous matter, which
lies over the passage from the third to the fourth ventricle, and, lower down,
covers in a part of the fourth ventricle itself. It is narrow above, where it
is connected with the quadrigeminal bodies, and broader below, where it
is continuous with the median portion of the cerebellum.
The upper portion of the valve is composed of white substance, but a few
transverse ridges of grey matter extend upon its lower half, as if they were
prolonged from the grey lamellae of the cerebellum with which the valve is there
continuous. From between the posterior quadrigeminal tubercles a slight
median ridge, named frmnulum, descends a little way upon the valve ;
and on the sides of this the commencing fibres of the fourth pair of
nerves pass transversely outwards. The back part of the valve is over-
lapped and concealed by the superior vermiform process of the cerebellum.
INTERNAL STRUCTURE OF THE CEREBRUM.
The cerebrum, like the rest of the encephalon, is composed of white and grey
substance, the white pervading nearly the whole of its extent, though more exclu-
sively composing its deeper parts ; the grey forming a covering of some thickness over
STRUCTURE OF THE FIBROUS SUBSTANCE. 555
the whole surface of the convolutions, and collected in distinct masses in certain of
the deeper part«, such as the corpora striata, thalami optici, corpora quadrigemina,
and crura cerebri. To the grey substance, the names of cineritious and cortical have
been applied ; to the white that of medullary.
1. The white matter of the encephalon consists of tubular fibres, in general still
smaller than those of the cord, and more prone to become varicose. The general
direction which these follow is best seen in a brain that has been hardened by
immersion in alcohol, although it is true that in an ordinary dissection of such
hardened masses with the scalpel, we do not then trace the single fibres, but only
the smaller bundles and fibrous lamellae which they form by their aggregation. It must
also be admitted that were they intimately decussate, the tearing of fibres across is
liable to be mistaken for the separation of sets of fibres one from the other ; and it
is necessary to correct such errors by the examination of sections under the micro-
scope. The microscopic examination of the cerebrum, however, is as yet still less
Fig. 378.
Fig. 378. — SKETCH OP A DISSECTION SHOWING THE CONNECTION OP THR COLUMNS OP THE
MEDULLA OBLONGATA WITH THE CEREBRUM AND CEREBELLUM (from Mayo), i
In the lower part of the figure the medulla oblongata is entire where it is prolonged
downwards into the spinal cord ; a, the anterior pyramid ; a', its continuation upwards
into the pons Varolii (m) ; c, olivary body ; cf, olivary fasciculus ; behind c', the fasciculi
teretes are represented ; d, the white laminae in part of the cerebellum ; /, superior
peduncle of the cerebellum ; y, anterior part or crust of the cerebral peduncle ; h, part
of the fibres radiating from the peduncle into the right cerebral hemisphere, of which a
considerable extent is shown containing parts of the anterior, middle, and posterior lobes ;
Ji, y, y, part of the corona radiata ; h' (in front), central fibres of the convolutions ; i,
fillet; I, back of the thalamus opticus ; m, pons Varolii; n, inferior peduncle of the
crus cerebelli ; o, section of the pes hippocampi ; r, tegmentum ; y, y, show the white
fibres issuing from the corpus striatum.
complete than that of the spinal marrow and medulla oblongata. By the dissection
of artificially prepared brains, aided in part by microscopic observation, the following
general facts have been ascertained.
The fibres of the cerebrum, though exceedingly complicated in their arrange-
ment, and forming many different groups, may be referred to three principal
systems, according to the general course which they take, viz. : — 1. Ascending or
o o 2
556
THE CEREBRUM.
peduncular fibres, which pass up from the medulla oblongata to the hemispheres,
and constitute the peduncles of the cerebrum. These fibres increase in number as
they ascend through the pons, and still further in passing through the optic thalami
and striated bodies, beyond which they spread in all directions into the hemispheres.
2. Transverse or commissural fibres, which connect the two hemispheres together.
3. Longitudinal or collateral fibres, which, keeping on the same side of the middle
line, connect more or less distant parts of the same hemisphere.
1. In each hemisphere the peduncular fibres consist of a main body and of certain
accessory bundles of fibres.
The main body is derived from the anterior pyramid, from the fasciculi teretes,
and from the posterior pyramid. After it has passed through the pons, and be-
come increased in amount, it is separated into two parts in the crus cerebri by a
layer of dark cineritious matter, named locus niger. The lower or superficial part,
which is derived from the pyramid, consist almost entirely of white fibres, col-
lected into coarse fasciculi, and is named the crust or basis, or the fasciculated por-
tion of the peduncle (Foville). The upper part, composed principally of the fasci-
culus teres and posterior pyramid, is named the tegmentum. It is softer and finer in
texture, and is mixed with much grey matter.
Still increasing in number within the peduncle, these two sets of fibres ascend to
the thalamus and corpus striatum. A much larger number of fibres diverging
Fig. 370. Fig. 379.— POSTERIOR VIEW
OK THE PEDUNCLES OF TUN
CEREBRUM AND CEREBEL-
LUM (after Arnold). f
The lower and fore part of
the cerebral hemispheres is
preserved, the cerebellum is
completely detached from its
peduncles, and on the right
side the corpora quadrigemina
and thalamus opticus have
been dissected, a, fasciculus
teres of the left side ; b, fibres
of the tegmentum ascending
through the right thalaraus ;
c, left corpora quadrigemina ;
d, lateral column of the cord ;
e, restiform body ; /, superior
peduncles of the cerebellum ;
g, fibres of the crust ; i, ?',
the fillets ; k, k, corpora
stria ta ; Z, the left thalamus ;
m, m, sections of the middle
peduncles of the cerebellum ;
n, section of the left inferior
peduncle ; p, left postei'ior
pyramid ; g, section of the
corpus callosum ; s, under
surface of the same, and below it the cavity of the fifth ventricle ; e, left anterior pillar
of the fornix; y, decussation of the radiating fibres with the crossing fibres of the corpus
callosum.
from these bodies appear to pass to the medullary substance of the hemispheres ; but
the actual continuity of the individual fibres spreading out in the hemisphere with
those ascending to the thalamus and corpus striatum is doubted by many authors,
and among them, by Kolliker.
The assemblage of radiating fibres in each hemisphere might be compared to a
fan, bent into the form of an incomplete hollow cone, having its concave surface
turned downwards and outwards ; hence the name corona radiata applied to them
by Reil, and fibrous cone by Mayo.
TRANSVERSE AND COLLATERAL FIBRES.
557
The accessory fibres of the peduncular system are as follows : —
a. The superior peduncles of the cerebellum, (processus ad cerebrum,) which are
continued up beneath the corpora quadrigernina, and form part of the tegmentum.
b. The bundle of fibres on each side, named the fillet (lemniscus). This, which is
originally derived from the anterior column of the cord, proceeds from the olivary
fasciculus of the medulla oblongata, as previously described. Reinforced by fibres
from the corpus dentatum of the olivary body, it ascends through the back part of
the pons, still increasing in size. Appearing at the side of the cerebral peduncle,
above the upper border of the pons, it divides into two portions, of which one crosses
over the superior peduncle of the cerebellum to the corpora quadrigemina, meeting
its fellow of the opposite side; while the other is continued upwards with the fibres
of the tegmentum.
c. Other fibres accessory to the peduncles take their rise in the grey matter of the
corpora quadrigemina (the brachia], and proceed on to the thalami.
d. Lastly, fibres of another set, having a similar destination, are derived from the
corpora geuiculata.
2. The transverse commissural, or connecting fibres of the cerebrum, include the
following sets.
a. The cross fibres of the corpus callosum pass laterally into the substance of
Fig. 380.
Fig. 380. —VIEW OF A DISSECTION OF TUB
FIBRES IN THE LEFT CEREBRAL HEMI-
SPHERE FROM BELOW (after Mayo). |
The most of the middle lobe in its lower
part has been removed. «, the anterior and
«', the posterior part of the fillet of the
corpus callosum ; b; g, section of the cms
cerebri ; b, tegmentum ; y, crust separated
from the last by the locus niger ; c', fibres
stretching from the back part of the corpus
callosum into the posterior lobe ; e, fasciculus
uncinatus connecting the anterior and middle
lubes across the Sylvian fissure ; /, /, trans-
verse fibres from the corpus callosum passing
into the cerebral hemispheres ; I, back part
of the thalamus ; m, corpus albicans ; q,
median section of the corpus callosum ; ;*,
radiating fibres of the hemispheres ; t, ante-
rior pillar of the fornix descending into the
corpus albicans (m) ; v, collateral fibres of
the convolutions ; x , anterior commissure.
the hemispheres, some being directed up-
wards, whilst others spread outwards on
the roof of the lateral ventricles, forming
there what is named the tapetum. Having
intersected the peduncular radiating fibres,
they spread out into the hemispheres,
reaching everywhere the grey matter of the
convolutions.
b. The fibres of the anterior commissure
pass laterally into the corpora striata, and bending backwards, extend a long way
into the middle of the hemispheres, on each side.
c. The fibres of the posterior commissure run through the optic thalami, and are
soon lost in the substance of the hemispheres outside these bodies.
3. The third system of fibres in the cerebrum, the longitudinal or collateral, in-
cludes those of the fornix, tsenia semicircularis, and striae lougitudinales of the
corpus callosum, already sufficiently described ; and likewise the following.
a. Fibres of the yyrus fornicatus ; fillet of the corpus callosum (Mayo).— These
fibres constitute the white substance of the gyms fornicatus, and take a longitudinal
course immediately above the transverse fibres of the corpus callosum. In front
558 THE CEREBRUM.
they bend downwards within the gyms to which they belong, and are connected
with the anterior perforated space, being joined by certain longitudinal fibres which
run along the under surface of the corpus callosum near the middle line, passing
near and upon the upper edge of the septum lucidum. Behind, they turn round the
back of the corpus callosum and thence descend to the point of the middle lobe, where,
according to Foville, they again reach the perforated space. Offsets from these fibres
pass upwards and backwards into the secondary convolutions derived from the gyrus
fornicatus in the longitudinal fissure.
b. fasciculus uncinat,us. — Under this name is described a white bundle, seen on
the lower aspect of the hemisphere, passing across the bottom of the Sylvian fissure,
and connecting the anterior with the middle and posterior lobes. The fibres of this
bundle expand at each extremity, and the more superficial of them are curved or
hooked sharply between the contiguous parts of the anterior and middle lobes, —
whence it has derived its name.
c. The convolutions of the cerebrum are connected with each other by white
fibres, which lie immediately beneath the cortical substance. Some of them pass
across the bottom of the suicus between adjacent convolutions ; whilst others, which
are longer and run deeper, connect convolutions situated at a greater distance from
one another.
Fig. 381.
Fig. 381. — VIEW OP A DISSECTION OP THE FIBRES OF THE GYROS FORNIOATUS AND FORNIX,
IN THE RIGHT HEMISPHERE ^sli^htiy altered from Foville). 4
A, the anterior lobe ; B, the posterior lobe ; a, a', a", fibres of the gyrus fornicatus ;
C, cf, oblique bands of fibres of some of its accessory gyri; b, tegtnentum, and g, crust of
the crus cerebri, separated by the locus niger ; I, thalamus ; m, fissure of Sylvius ; n, corpus
albicans ; q, median section of the corpus callosum ; s, septum lucidum ; t, the fornix,
its anterior pillar descending into the corpus albicans, and then emerging from that at its
termination (*) in the thalarnus ; 1, the olfactory bulb ; 2, the optic commissure.
The researches of Foville have led him to differ considerably from other
anatomists as to the course of the fibres of the cerebrum, as will be seen from the
following statement of his views.
1. The crust or fasciculated portion of each cerebral peduncle, derived from the
anterior pyramid, forms by itself the peduncular fibrous cone, and is thence con-
tinued on into the radiating fibres of the cerebrum, which are destined only for the
convolutions on the convex surface of the hemisphere, including the outer half of
the marginal convolution of the longitudinal fissure, and the inner half of the con-
volution of the Sylvian fissure.
2. The fibres of the tegmentum, having entered the thalamus, pass on in two ways
— no part of them, however, joining the radiating peduncular fibres.
a. One set pass upwards through the thalamus and corpus -triatum, above which
FIBROUS STRUCTURE.— FOVILLE'S VIEWS.
559
they then turn inwards, and, joining with those of the opposite side, form the trans-
verse fibres of the corpus callosum. The corpus callosum is therefore regarded as
a commissure of the cerebral peduncles only — none of its cross fibres spreading into
the convolutions, as is generally believed.
b. The second set of fibres of the tegmentum, corresponding with the fasciculi
teretes and part of the posterior pyramids, run forwards near the middle line, along
the under side of the third ventricle and corpus striatum, through the grey matter
in front of the pons, to the anterior perforated space. The remaining part of the
posterior pyramid forms the taenia semicircularis, which, passing down in front of the
anterior pillar of the fornix, also reaches the perforated space. From this space
more fibres are reflected upwards on the sides of the corpus striatum to join the
corpus callosum.
3. As dependencies of the posterior peduncular fibres, and connected with them at
the borders of the anterior perforated space, are : —
a. Several sets of longitudinal arched fibres, which embrace, in a series of rings,
the radiating peduncular system. These are — the deep fibres of the taenia semicircu-
laris— a somewhat similar baud beneath the outer part of the corpus striatum — the
half of the fornix with the corpus fimbriatum— the longitudinal fibres placed on the
upper and under surface of the corpus callosum, and those of the septum lucidum ;
and, lastly, two remarkable systems of longitudinal fibres — one constituting the
entire white substance of the gyrus fornicatus (from end to end), also of its accessory
convolutions, and of the inner half of the marginal convolution of the longitudinal
fissure ; and the other, forming the white substance of the convolutions of the island
of lieil, and the adjoining half of the convolution of the Sylvian fissure. None of
the parts just named receive fibres from the radiating peduncular set.
6. In connection with this system is a thin stratum of white fibres, found upon the
internal surface of the ventricles, aud prolonged through the transverse fissure into
the reticulated white substance covering the lower end of the gyrus fornicatus ;
whence, according to Foville, it extends, as an exceedingly thin layer of medullary
matter, all over the cortical substance of the hemisphere.
c. The anterior commissure does not reach the convolutions, but radiates upon the
outer sides of the corpora striata and thalami.
II. The fjrvij matter on the convoluted surface of the cerebrum is divided into two.
and in some regions into three strata, by interposed thin layers of white substance.
In examining it from without inwards, we meet with — 1. A thin coating of white
matter situated on the surface, which on a section appears as a faint white line,
bounding the grey surface externally. This superficial white layer is not equally
Fig. 382.— SECTION OP Fig. 382.
THE COKTICAL SlJB-
STANCE OF A CEREBKAL
CONVOLUTION (from
Remak).
In A, the parts are
nearly of the natural
size. To the right of the
figure, a and e are two
white, and b and / two
grey strata ; to the left
of the figure, an addi-
tional whi^e layer, ^di-
vides the first grey into
two, b and d. In B, a
small part of the cortical
substance of a con volution
is represented, magnified
to show more clearly the
relative position of the strata ; a, superficial white layer ; 6, reddish grey layer ; c, inter-
mediate white layer; d, inner part of the outer grey layer ; e, thin white layer; /, inner
grey layer ; g, radiatiug white fibres from the medullary substance of the convolution
passing into the layers of the cortical substance.
560
THE CEREBRUM.
thick over all parts of the cortical substance, but becomes thicker as it approaches
the borders of the convoluted surface ; it is accordingly less conspicuous on the
lateral convex aspect of the hemispheres, and more so on tho convolutions situated in
the longitudinal fissure which approach the white surface of the corpus callosum, and
on those of the under surface of the brain. It is especially well marked on the
middle lobe, near the descending cornu of the lateral ventricle, where the convo-
luted surface is bounded by the posterior pillar of the fornix, and it has been there
described under the name of the reticulated wliite, substance. It consists of remark-
ably fine tubular fibres, for the most part varicose, which run parallel with the sur-
face of the convolutions, but intersect each other in various directions. The ter-
mination and connections of these fibres are unknown. This superficial white layer
contains also a few small cells with processes, and an abundant granular matrix.
2. Immediately beneath the white layer just described, is found a comparatively thick
layer of grey or reddish grey matter, the colour of which, as indeed of the grey sub-
stance generally, is deeper or lighter according as its very numerous vessels contain
much or little blood. Then follow, 3. Another thin whitish layer; and 4. A thin
grey stratum. This last lies next to the central white matter of the hemisphere.
Remak considers it as similar in nature to the gelatinous substance of the spinal
cord. According to this account, the cortical substance consists of two layers of grey
substance, and two of white ; but in several convolutions, especially those situated
near the corpus callosum, a third white stratum may be seen, which divides the
most superficial grey layer into two, thus making six in all, namely, three grey and
three white.
Fig. 3 S3.
Fig. 383.— MINUTE STKUCTUKK OF THE CEREBRAL SUBSTAKO ; (from Kolliker), MAGNIFIED
220 DIAMETERS.
A, cells and structural elements from the inner part of the cortical substance of the
cerebral convolutions ; a, larger cells, chiefly from the middle grey layer, showing a
variable number of radiating processes; b, smaller cells from the more superficial grey
layer, in part belonging to connective tissue; c, a nerve-fibre with its axis-filament
partly exposed.
B, finest nerve-fibres from the superficial wliite layer of the cortical substance of a
convolution, some showing the varicose condition.
The cortical grey substance consists of nerve-cells of rather variable size, which are
angular, fusiform, round, or oval in shape, and for the most part caudate, and lie in a
granular matrix; also of small nucleus-like vesicles, which resemble those seen in
the cortical substance of the cerebellum, and, according to Todd, are here also
collected into a special stratum. In the middle grey layer, the cells are of variable
gize, some being so small as to resemble nuclei ; but others of much larger dimen-
sions are abundant, and, according to Kolliker, present from one to six processes.
CORTICAL AND INTERNAL GREY SUBSTANCES. 561
In the innermost grey layer the cells have similar characters, but often contain
pigmentary matter. Tubular fibres exist throughout : those of one set run parallel
with the surface, and at certain depths are more densely aggregated, so as to form
the before-mentioned white layers : they are also present in the intervening grey
strata, but there they are wider apart. The manner in which they begin and end is
not known ; it seems not improbable, however, that they are dependencies of the
commissural system of fibres. These stratified fibres, if they might be so called, are
intersected by another set of tubular fibres, which come from the central white
mass of the hemispheres, and run perpendicularly through the cortical substance,
becoming finer and spreading more out from each other as they approach the surface.
The further disposition of these central or perpendicular fibres is uncertain;
Yalentin describes them as forming terminal loops or arches, but this is denied by
Remak and Hannover. Remak states that they gradually disappear from view at
different depths, as they pass through the successive layers, the last of them vanish-
ing in the superficial grey stratum ; but he is unable to say positively how they
terminate. It sometimes seemed to him as if the last of them, after intersecting the
fibres of the deeper white stratum, became continuous with those of the outermost
layer ; but of this he by no means speaks confidently. Hannover maintains that
the perpendicular fibres are connected at their extremities with the nerve-cells in the
cortical substance.
The grey matter of the lamina cinerea, tuber cinereum, and posterior perforated
spot, appears both in the base of the brain and in the floor of the third ventricle.
The lamina cinerea is connected externally with the grey matter of the anterior
perforated spot, and from that point a continuity of grey matter can be traced to
the swelling of the olfactory bulb. Thus also continuity is established between the
grey matter of the hemispheres and that of the interior of the brain.
III. The grey matter of the interior of the cerebrum may be examined in the series
of its deposits from behind forwards.
In the crura cerebri, the grey matter is collected into a dark mass, the locus
niger, which lies between the crust and the tegmentum, and is also diffused among
the fasciculi of the tegmentum ; below this it is continuous with that of the pons
and medulla oblongata, and through them with that of the spinal cord, as has already
been sufficiently described. In the upper part of each tegmentum is a round reddish
grey centre, the red centre of Stilling, the superior olive of Luys.
In the centre of each of the corpora quadrigemina grey matter is also found ; and
this collection is stated by Huschke to be continuous below with the posterior cornu
of the grey matter of the spinal cord, posteriorly with that of the corpus dentatum
of the cerebellum, and anteriorly with the soft commissure, the septum lucidum,
optic thalami, and corpus callosum. Grey matter occurs also in the pineal gland,
and in the corpora geniculata. These last bodies appear to be_ appendages of the
optic thalami.
The grey matter of the optic thalamus constitutes the principal bulk of that body ;
it is, however, partially divided into an inner and an outer portion, by white fibres
passing through it.
The corpus striatum contains three grey centres. That which forms the intra-
ventricular portion of the body, and is connected inferiorly with the lamina cinerea,
and with that portion of the grey matter of the optic thalamus which is seen in the
third ventricle, is named the nucleus caudatus. The principal centre of the extra-
ventricular portion, named nucleus lenticularis, external and inferior to the nucleus
caudatus, is separated from that centre by the white substance of the fibrous cone,
which, as it passes outwards, appears, when cut across, as a broad white band extend-
ing from behind forwards, and traversed by striae of grey matter passing from one
centre to the other. Between the nucleus lenticularis and the island of Reil, which
lies opposite to it, there intervenes a thin lamelliform deposit of grey matter, the
nucleus tceniceformis (Arnold), or claustruin (Burdach), which, in a transverse section,
is seen as a thin line. The lenticular nucleus is continuous with the grey matter of
the anterior perforated space.
The corpus striatum and optic thalamus contain cells very much like those of the
cortical substance. In the corpora quadrigemina there are larger cells, approaching
in size to those of the cerebellum, besides very small cells and nucleiform bodies.
The dark matter, forming the so-called locus niger of the cerebral peduncles, and
562
CEREBRO-SPINAL MEMBRANES.
that in the floor of the fourth ventricle, contain caudate cells, many of them of the
largest size, with long appendages, and deeply coloured with pigment. (Hannover,
Rech. Microscop. sur le Systeme Nerveux. Copenhagen, 1844).
The pineal body, like the pituitary body, has already been sufficiently described.
The deep connection of some of the cranial nerves with the basal parts of the cere-
brum, as well as that of others with the remaining portions of the encephalon, will
be referred to in the description of these nerves.
THE MEMBRANES OF THE BRAIN AND SPINAL CORD.
The cerebro-spinal axis is protected by three membranes, named also
meninges. They are : — 1. Au external fibrous membrane, named the dura
mater, which closely lines the interior of the skull, and forms a loose sheath
in the spinal canal ; 2. An internal areolo-vascular tunic, the pia mater,
which accurately covers the brain and spinal cord ; and 3. An intermediate
serous sac, the arachnoid membrane, wLich, by its parietal and visceral
layers, covers the internal surface of the dura mater on the one hand, and
is reflected over the pia mater on the other.
THE DURA MATER.
The dura mater, a very strong dense inelastic fibrous tunic of considerable
thickness, is closely lined on its inner surface by the outer poition of the
Fig. 384.
Fig. 384. — THE CRANIUM OPENED TO snow THE FALX OP THE CEREBRUM, AND TENTORIUM
OF THE CEREBELLUM. 4
a, right side of the falx cerebri ; a', its anterior narrow part attached to the crista
galli ; 6, tentorium cerebelli of the right side, united to the base of the falx cerebri
from 2 to 3, in the Hue of the straight sinus, and attached to the superior border
of the petrous bone between 3 and 3' ; b', aperture between the right and left divisions
of the tentorium for the isthmus cerebri ; 1, 1, the superior longitudinal sinus; 2, 2, the
inferior ; 3, 3, the lateral sinus; 3, 3', the superior petrosal sinus j 3', is close to the
anterior clinoid process.
DUEA MATER.— FALX.-TEXTOKIUM. 563
arachnoid, and with it, therefore, forms a fibro-serous membrane, which is
free, smooth, and epitheliated on its inner surface, where it is turned
towards the brain and cord, but which, by its outer surface, is connected
with the surrounding parts, in a somewhat different manner in the cranium
and in the spinal canal.
The outer surface of the cranial portion adheres to the inner surface of
the bones, and forms their internal periosteum. The connection between
the two depends, in a great measure, on blood-vessels and small fibrous
processes, which pass from one to the other ; and the dura mater, when
detached and allowed to float in water, presents a flocculent appearance on
its outer surface, iu consequence of the torn parts projecting from it. The
adhesion between the membrane and the bone is more intimate opposite
the sutures, and also generally at the base of the skull, which is uneven,
and perforated by numerous foramina, through which the dura mater is
prolonged to the outer surface, being there continuous with the pericranium.
The fibrous tissue of the dura mater becomes blended with the areolar
sheaths of the nerves, at the foramina which give issue to them.
In leaving the skull, the dura mater is intimately attached to the margin
of the foramen magnum ; but within the vertebral canal it forms a loose
sheath around the cord (#ieca), and is not adherent to the bones, which
have an independent periosteum. Towards the lower end of the canal, a
few fibrous slips proceed from the outer surface of the dura mater to be
fixed to the vertebrae. The space intervening between the wall of the
canal and the dura mater is occupied by loose fat, by watery areolar tissue,
and by a plexus of spinal veins.
Opposite each iutervertebral foramen the dura-matral theca presents two
openings, placed side by side, which give passage to the two roots of the
correspond! Lg spinal nerve. It is continued as a tubular prolongation on,
the nerve, and is lost in its sheath. Besides this, it is connected with
the circumference of the foramen by areolar tissue.
The fibrous tissue of the dura mater, especially within the skull, is divi-
sible into two distinct layers, and at various places these layers separate
from each other and leave intervening channels, called sinuses. These
sinuses, which have been elsewhere described, are canals for venous blood,
and are lined with a continuation of the internal membrane of the veins.
The dura mater also sends inwards into the cavity of the skull three
strong membranous processes, or partitions^ formed by duplication of its
inner layer. Of these, one descends vertically in the median plane, and is
received into the longitudinal fissure between the two hemispheres of the
cerebrum. This is thj falx cerebri. The second is an arched or vaulted
partition, stretched across the back part of the skull, between the cerebrum
and the cerebellum ; it is n amed the tentorium cerebelli. Below this, another
vertical partition, named falx cerebelli, of small extent, passes down between
the hemispheres of the cerebellum.
The /ate cerebri is narrow in front, where it is fixed to the crista galli,
and broader behind, where it is attached to the middle of the upper surface
of the tentorium, along which line of attachment the straight sinus is
situated. Along its upper convex border, which is attached above to the
middle line of the inner surface of the cranium, runs the supeiior longi-
tudinal sinus. Its under edge is free, and reaches to within a short distance
of the corpus callosum, approaching nearer to it behind. This border con-
tains the inferior longitudinal sinus.
The tentorium, or tent, is elevated in the middle, and declines downwards
564 CEREBRO-SPINAL MEMBRANES.
in all directions towards its circumference, thus corresponding in form with
the upper surface of the cerebellum. Its inner border is free and concave, and
leaves in front of it an oval opening, through which the isthmus encephali
descends. It is attached behind and at the sides by its convex border to
the horizontal part of the crucial ridges of the occipital bone, and there
encloses the lateral sinuses. Farther forward it is connected with the upper
edge of the petrous portion of the temporal bone — the superior petrosal
fcinus running along this line of attachment. At the point of the pars
petrosa, the external and internal borders meet, and may be said to inter-
sect each other — the former being then continued inwards to the posterior,
and the latter forwards to the anterior clinoid process.
The falx cercbelli (falx minor) descends from the middle of the posterior
border of the tentorium with which it is connected, along the vertical ridge
named the internal occipital crest, towards the foramen magnum, bifurcating
there into two smaller folds. Its attachment to the bony ridge marks the
course of the posterior occipital siuus, or sinuses.
Structure. — The dura mater consists of -white fibrous and elastic tissue, arranged in
bands and laminae, crossing each other. It is traversed by numerous blood-vessels
•which are chiefly destined for the bones. Minute nervous filaments, derived from
the fourth, fifth, and eighth cranial nerves, and from the sympathetic, are described
as entering the dura mater of the brain. Nervous filaments have likewise been
traced in the dura mater of the spinal column. (Luschka and Riidinger, quoted by
Hyrtl.)
THE PIA MATER.
The pia mater is a delicate, fibrous, and highly vascular membrane,
which immediately invests the brain and spinal cord.
Upoii the hemispheres of the brain it is applied to the entire cortical
surface of the convolutions, and dips into all the sulci. From its internal
surface very numerous small vessels enter the grey matter and extend for
some distance perpendicularly into the substance of the brain. The inner
surface of the cerebral pia mater is on this account very flocculent, and is
named tomentum ceiebri. On the cerebellum a similar arrangement exists,
but the membrane is finer and the vessels from its inner surface are not so
long. The pia mater is also prolonged into the ventiicles, and there forms
the velum interpositum and choroid plexus.
Structure.— The pia mater consists of interlaced bundles of areolar tissue, con-
veying great numbers of blood-vessels ; and, indeed, its peculiar office, both on the
brain and spinal cord, seems to be that of providing a nidus or matrix for the
support of the blood-vessels, as these are subdivided before they enter the nervous
substance. According to Fohmann and Arnold, it contains numerous lymphatic
vessels. Purkinje describes a i etiform arrangement of nervous fibrils, derived, accord-
ing to Kolliker and others, from the sympathetic, the third, sixth, facial, pneumo-
gastric. and accessory nerves.
On the spinal cord the pia mater has a very different structure from that
which it presents on the encephalon, so that it has even been described by
Home as a different membrane under the name neurilcmma of Hie cord. It
is thicker, firmer, less vascular, and more adherent to the subjacent nervous
matter : its greater strength is owing to its containing fibrous tissue, which
is arranged in longitudinal shining bundles. A reduplication of this mem-
brane dips down into the anterior fissure of the cord, and serves to conduct
blood-vessels into that part. A thinner process passes into the greater part
of the posterior fissure. At the roots of the nerves, both in the spine and
SUBARACHXOID SPACE AXD FLUID. 565
in the cranium, the pia mater becomes continuous with the neurilemma. It
is supplied with nerves from the sympathetic.
Towards the upper part of the cord, the pia mater presents a greyish
mottled appearance, which is owing to pigment particles deposited within
its tissue.
THE ARACHNOID MEMBRANE.
The arachnoid is a very fine delicate serous membrane, which, like other
membranes of thab class, forms the lining boundary of a shut sac. The
walls of this sac consist of two portions, one of which, a distinct membrane
on the surface of the pia mater, is the visceral or cerebral layer of the
arachnoid, while the other, giving the smooth surfaca presented by the dura
mater on its interior, is described by some anatomists as the parietal layer
of the arachnoid, while, according to the view taken by others, it is merely
the serous surface of the dura mater.
The parietal wall of the arachnoid space is invested with a layer of polygonal
epithelial cells, which are flattened and nucleated. Besides this, it presents
in the greater part of its extent no tissue distinct from the dura mater ; and
hence it is that Koiliker and others object to the term parietal layer of
the arachnoid membrane as applied to the structure of this surface. It may
be mentioned, however, that in certain recesses, as for example at the sides
of the crista galli, and between the trabeculse into which the deep fibres of
the dura mater are thrown in the neighbourhood of the superior longitudinal
sinns, a small amount of delicate connective tissue beneath the epithelium
may be distinguished from the dense fibres of the dura mater.
The visceral layer of the arachnoid is a distinct transparent membrane
which passes over the various eminences and depressions on the cerebrum
and cerebellum, without dipping into the sulci and smaller fissures ; nor is
it uniformly and closely adherent to the pia mater. The interval left
between the arachnoid membrane and pia mater is named generally the
subarachnoid space.
This subarachnoid space is wider and more evident in some positions than
in others. Thus, in the longitudinal fissure, the arachnoid does not descend
to the bottom, but passes across, immediately below the edge of the falx, at
a little distance above the corpus callosum. In the interval thus left, the
arteries of the corpus callosum run backwards along that body. At the
base of the brain and in the spinal canal there is a wide interval between
the arachnoid and the pia mater. In the base of the brain, this subarachnoid
space extends in front over the pons and the interpeduncular recess as far
forwards as the optic nerves, and behind it forms a considerable interval
between the cerebellum and the back of the medulla oblongata. In the
spinal canal it surrounds the cord, forming a space of considerable extent.
A certain quantity of fluid is contained between the arachnoid membrane
and the dura mater ; but it has been shown by Magendie that the chief part
of the cerebro-spinal fluid is lodged under the arachnoid, in the subarachnoid
space.
Magendie also pointed out the existence of a sort of septum dividing the
spinal subarachnoid space at the back of the cord. This is a thin mem-
branous partition, which passes in the median plane from the pia mater
covering the posterior median fissure of the cord to the opposite part of the
loose portion of the arachnoid membrane. It is incomplete and cribriform ;
and consists of bundles of white fibres interlaced more or less with one
another. Fibrous bands of the same texture pass across the subarachnoid
566 CEREBRO-SPINAL MEMBRANES.
space in various situations both within the spinal canal and at the base of
the brain, stretching thus from the arachnoid membrane to the pia mater.
Fig. 385. — TRANSVERSE SECTION OF THE SPINAL
CORD AND ITS ENVELOPES (from Sappey after
Hirschfeld and Leveille).
1, dura mater or tbeca ; 2, parietal layer of
the arachnoid membrane: 3, internal or loose
.arachnoid ; 4 and 7, snbarachnoid cavity or
space ; 5, hinder part of the antero-lateral
column; 6, space between the arachnoid and the
dura mater, or between the inner and outer folds
of the arachnoid membrane : 8, reflection of the
one fold into the other; 9, sheath furnished to the spinal nerve by the dura mater; 10,
posterior ganglionic root; 11, smaller anterior root; 12, section of the ligamentum
denticulatum. This figure does not show the septum which posteriorly divides the
subarachnoid space into right and left parts : this would be placed between the arachnoid
at 3, and the pia mater covering the posterior surface of the cord.
As the cerebral and spinal nerves proceed to their foramina of exit from
within the dura mater, they are loosely surrounded by tubular sheaths of
the arachnoid membrane, which extend along each nerve from the visceral
to the parietal layer.
Structure. — When examined under the microscope, the visceral or true arach-
noid is found to consist of very distinctly separated riband-like bundles of fibrous
tissue interlaced with one another, and a simple layer of scaly epithelium on the
surface. Volkmann has described a rich plexus of nerves in the arachnoid mem-
brane of certain ruminants. Kolliker has failed to detect their presence ; but they
have been again described by Bochdalek, who traces them to the portio minor of the
fifth, the facial, and accessorius nerves; and they have likewise been followed by
Luschka.
Cerebro-spinal fluid. — This is a very limpid serous fluid, which occupies the sub-
arachnoid space. When collected immediately after death, its quantity was found
by Magendie in the human subject to vary from two drachms to two ounces. It is
slightly alkaline, and consists, according to an analysis by Lassaigne, of 98 '5 parts
of water, the remaining 1 '5 per cent, being solid matter, animal and saline. In
experiments made on the dog, it was found by Magendie to be reproduced in thirty-
six hours, after it had been drawn off by puncturing the membranes at the lower
part of the cord. When pressure is made upon the brain, the quantity of fluid in the
spinal subarachnoid space is increased, and conversely, it may be forced from the
spinal cavity upwards into the cranium.
Ligamentum denticulatum. — This is a narrow fibrous band which runs along
each side of the spinal cord in the subarachnoid space, between the anterior
and posterior roots of the nerves, commencing above at the foramen mag-
num, and reaching down to the lower pointed end of the cord. By its
inner edge this band is connected with the pia mater of the cord, while its
outer margin is widely denticulated ; and its denticulations, traversing the
arachnoid space, with the arachnoid membrane reflected over them, are
attached by their points to the inner surface of the dura mater, and thus
serve to support the cord along the sides and to maintain it in the middle
of the cavity. The first or highest denticulation is fixed opposite the
margin of the foramen magnum, between the vertebral artery and the
hypoglossal nerve ; and the others follow in order, alternating with the
successive pairs of spinal nerves. In all, there are about twenty-two of
these points of insertion. At the lower end, the ligamentum denticulatum
GLAKDUL2E PACCHIOXI. -BLOOD-VESSELS. 567
may be regarded as continued into the terminal filament of the spinal
cord, which thus connects it to the dura mater at the lower end of the
sheath. (See Figures 341 and 342.)
Structure, — It consists of white fibrous tissue, mixed with many exceedingly fine
elastic fibres which are seen on applying acetic acid. It is obviously continuous
on the one hand with the fibrous tissue of the pia mater, and on the other with that
of the dura mater.
The pia mater of the cord presents a conspicuous fibrous band, running
down in front over the anterior median fissure. This was named by Haller,
linea splendens.
Glandules Pacchioni. — Upon the external surface of the dura mater, in
the vicinity of the longitudinal sinus, are seen numerous small pulpy-looking
elevations, generally collected into clusters, named glands of Pacchioni.
The inner surface of the calvarium is marked by little pits, which receive
these eminences. Similar excrescences are seen on the internal surface of
the dura mater, and upon the pia mater on each side of the longitudinal
sinus, and also projecting into the interior of that sinus. Occasionally they
are found also in other situations.
These bodies are not found at birth ; and according to the brothers
Wenzel, they exist only in very small number, if at all, before the third year.
After the seventh year they are usually found, and they increase in number
greatly as life advances ; in some cases, however, they are altogether want-
ing. In animals there appears to be no corresponding structure.
On a careful examination of the connections of these bodies it will be
found that the elevations, found on the outer surface of the dura mater and
within the longitudinal sinus, in no instance take origin in those positions,
but that they are grape-like bodies which are attached more deeply, and in
their growth have perforated the dura mater. Their precise origin and nature
were long the subject of conflicting opinions, but it has been satisfactorily
shown by Luschka that they are only an enlarged condition of normal villi
of the arachnoid, and that no other structure is involved in their formation.
Their most prolific source is, as one may very soon discover, the cerebral or
generally acknowledged layer of the arachnoid, but they likewise arise in a
similar manner from the serous surface of the dura mater, and may some-
times be found of all sizes in the recesses into which that surface is thrown
in the neighbourhood of the longitudinal sinus. (Luschka, in Miiller's
Archiv. 1852 ; and " Die Adergeflechte des Menschlichen Gehirns," 1855.
See also Cleland " On Tumours of the Dura Mater, &c.," in the Glasgow
Medical Journal, 1863.)
BLOOD- VESSELS OF THE BRAIN AND SPINAL CORD.
The origin and course of these vessels have already been described in the
Section Angeiology. In passing to their distribution the several arteries,
having passed across the arachnoid cavity, enter the subarachnoid space an I
then divide and subdivide into branches, which, in their farther ramification
in the nervous centres, are supported by the pia mater, and, it may be
remarked, are more deeply placed in the various fissures and sulci than the
small veins, which do not accompany the arteries, but pursue a different
course and are seen upon the surface of the pia mater.
Moreover, it is to be observed that, whilst the main branches of the
arteries are situated at the base of the brain, the principal veins tend
568
SIZE AND WEIGHT OF THE BRAIN.
towards the upper surface of the hemispheres, where they enter the superior
and inferior longitudinal sinuses : the veins of Galen, however, coming
from the lateral ventricles and choroid plexuses, run backwards to the
straight sinus.
SIZE AND WEIGHT OF THE ENCEPHALON.
In the following table illustrating the average weight of the adult male and female
brain, the results obtained by Sims, Clendinning, Tiedemann, and J. Reid have
been brought together in such a form as to exhibit in groups the most commonly
prevailing weight ; the numbers being also simplified by the omission of fractions.
(Sims, " Medico-Chirurg. Trans.," vol. xix., pp. 353—7; Clendinning, "Medico-
Chirurg. Trans.," vol. xxi., pp. 59 — 68; Tiedemann, "Das Him des Negers,"
Heidelberg, 1837, pp. 6, 7; Reid, "London and Edinburgh Monthly Journal of
Medical Science," April, 1843, p. 298, &c.)
Table of the Average Weight of the Male amd Female Brain.
MALES, aged 21 years and upwards.
FEMALES, aged 21 years and upwards.
>
IS umber ot brains
at each weight
observed by
1
1
Number of brains
at each weight
observed ty
1
Classification
5
'
s^ -r- VMiiao&uva b&uu
£ -^ into three
eS
'""
-s
"£ .
into three
si
a
c
groups
fi 'S to show the
*1
*
,
It
S'S
groups,
to show the
gl
bo
1
1
§
g ^ prevailing
weight.
|
1
I *
1— 1
prevailing
ictight.
1
a
«
a
1
s 1
53 o
1
0
C/j
a
"§
•3 i^
0
i
H
M
H
6
a
H
tf p1
34
_
1 1 >>
31
i
1
1 ^
37
2
2
32
i
1
a
38
1
1
rH
35
2
oj / from ~i g
39
40
41
42
2
3
2
3
4
-
1
1
2
4
3
5
8
S r from ^ o
X 1 1 o
ji 3\r hi
» I 45 oz. J jg
36
39
i
4 ! —
3 j 1
3 1
2
2
4
6
2
6
Si 31 oz. f c
>• <S \ ° 4. J- O
o J to 1 •-
g \ 40 oz. J JG
5
43
—
6
2
3
11
^
40
3
3
4
10 ;
44
1
6
2
3
12
41
2
8 --
2
12 >!
45
46
47
48
6
2
2
4
8
10
6
8
2
1
8
10
11
>C O 00 >O
r-H CM rH 04
*
§ r from ^ g
42
43
44
45
3
6
5
4
6
4
9
1
3
7
13
7
19
20
« f from -\ ^
3 ' 41 oz. F §
*!l to ii
<3 v. 47 oz. J «>
49
3
2
2
12
19
c« J 46 OZ. f S
46
2
9 2
12
25
4
4
5
13
26
° i *° I 0
47
2
5
7
14 J
s
5!
3
3
2
19
27
S I. 53 oz. J ta
48
2
2
2
6 ^
52
—
5
4
6
15
p
49
1
2
7
10
00
53
54
II
4
3
2
2
4
1
2
1
10
5
4
6
20
11
50
52
53
1
1
1
2
4
4
7
6
9 ( from "i §
,SJ 4802. F|
§ J to f C
Si 56oz. Js§
57
58
1
4
o
2
7
1C ?ro^ II
54 —
56 i —
2
1
—
— 2
— 1 x
P
59
60
61
-
1
2
2
3
1
1
; m -vr j-|
J hg (. 65 oz. J j§
Tot. 30 + 72+12 + 77=191
62
—
—
T
i S
63
—
—
1
i 1
6q —
—
1 ~
i ;
Tot. 35 + 78 + 39 + 126 = 278.
According to this table, the maximum weight of the adult male brain, in a series of
278 cases, was 65 oz., and the minimum weight 34 oz. In a series of 191 cases, the
maximum weight of the adult female brain was 56 oz., and the minimum 31 oz. ; the
difference between the extreme weights in the male subject being no less than 31 oz.,
and in the female 25 oz. By grouping the cases together in the manner indicated by
brackets, it is shown that in a very large proportion the weight of the male brain
TABLE OF THE WEIGHT OF THE BRAIN.
569
ranges between 46 oz. and 53 oz., and that of the female brain between 41 oz. and
47 oz. The prevailing weights of the adult male and female brain may therefore be
said to range between those terms ; and, by taking the mean, an average weight is
deduced of 49| oz. for the male, and of 44 oz. for the female brain,— results which
correspond closely with the statements generally received.
Although many female brains exceed in weight particular male brains, the general
fact is sufficiently shown, that the adult male encephalon is heavier than that of the
female, — the average difference being from 5 to 6 oz. This general superiority in
absolute weight of the male over the female brain has been ascertained to exist at
every period of life. In new-born infants the brain was found by Tiedemann to weigh
on an average from 14| oz. to 15| oz. in the male, and from 10 oz. to 131 oz. in the
female : — a fact of considerable interest in practical midwifery, for it has been shown
that difficult labours occur in by far the largest number in the birth of male children .
(Simpson, London and Edinburgh Monthly Journal of Medical Science, 1845.)
With the above results the observations of Peacock, published in the " Monthly
Journ. of Med. Science " for 1847, and further observations by the same author in the
" Journ. of the Pathol. Soc." in 1860, in the main agree.
The elaborate table compiled by Rudolph Wagner, and published in his " Yorstudien
zu einer Wissensch. Morphol. und Physiol. des Menschl. Gehirns," 1860, containing
964 recorded cases in which the weight of the brain had been ascertained, may also be
referred to as another recent useful contribution to the knowledge of this subject.
In illustration of the variation in the average weight of the brain at different ages
the following table is given, deduced from the elaborate researches of Dr. Robert
Boyd, in the examination of the brains of 2,086 sane persons of both sexes dying in the
St. Marylebone Infirmary, and published in the Philos. Trans, for 1860. The weights
are stated in oz. avoird. and decimal fractions of them.
Table of the Weight of the Brain of Males and Females at different Ages.
PERIODS OF LIFE.
MALES.
FEMALES.
Number
weighed.
Maximum.
EJ
1
Average.
Average.
9
|
Number
weighed.
1 Children prematurely still-
born
25
43
42
16
15
46
34
29
27
22
19
59
no
J37
119
127
104
24
13.1
22.
15.37
32.75
30.75
36.13
41.25
50.5
49.5
57.25
58.5
57.
60.75
60.
59.
59.5
55.25
53.75
1.31
9.37
6.
10.5
1'>.75
17.75
23.25
30.5
24.5
39.25
36.5
39.25
33.75
33.75
30.5
36.25
37.75
41.
5.6
13.87
11.65
17.42
21.29
27.42
33.25
38.71
40.23
45.96
48.54
47.9
48.2
47.75
47.44
46.4
45.5
45.34
4.62
12.25
10.
15.94
19.76
25.7
29.8
34.97
40.11
40.78
43.94
43.7
43.09
42.81
43.12
42.69
41.27
39.77
1.29
8.
1.75
11
13.
16.37
18.
27.75
34.75
34.
37.5
35.75
33.25
27.5
36.25
32.5
29.25
33.25
9.13
15.12
16.
32.5
34.75
39.13
37.
44.5
£25
•
55.25
53.
52.5
52.5
54.
49.5
48.
18
3i
39
20
25
40
33
29
19
18
16
72
89
106
103
149
148
77
2 Children still-born at full
period
4 Under 3 months
5 From 3 to 6 months
6 From 6 to 12 months
7 From 1 to 2 years
8 From 2 to 4 years
9 From 4 to 7 years
10 From 7 to 14 years
11 From 14 to 20 years ..
12 From 20 to 30 years
13 From 30 to 40 years
14 From 40 to 50 years
15 From 50 to 60 years
16 From 60 to 70 years
17 From 70 to 80 years
18 Upwards of 80 years
be 1 Persons above 14 years
^.5
> ~ I Persons from 14 to 70 years . .
< )
699
57i
58.
59.12
36.1
35.
47.1
47.7
42.5
43.15
33.1
33.8
52.1
53.15
760
535
Anatomists have differed considerably in their statements as to the period at which
the brain attains its full size, and also as to the effect of old age in diminishing the
weight of this organ. Soemmerring held that the brain reached its full size as early
P P
570 SIZE AND WEIGHT OF THE BRAIN.
as the third year ; the Wenzels and Sir W. Hamilton fixed the period about the seventh ,
and Tiedemann between the seventh and eighth years. Gall and Spurzheim were
of opinion that the brain continued to grow until the fortieth year. The observations
of Sims, Tiedemann, and Eeid, appear to show that in both sexes the weight of
the brain in general increases rapidly up to the seventh year, then more slowly to
between sixteen and twenty, and again more slowly to between thirty-one and forty,
at which time it reaches its maximum point. Beyond that period there appears a
slow but progressive diminution in weight of about 1 oz. during each subsequent
decennial period ; thus confirming the opinion that the brain diminishes in advanced
life. According to Peacock, the maximum weight of the brain is attained between
the ages of twenty and thirty years. The table of Boyd inserted above would appear
to show a somewhat earlier period as that at which the maximum is reached in both
sexes, and that the period of decline scarcely begins before sixty years. With this
result the observations of Huschke, made upon the brains of 359 men and 245 women,
in general agree. (" Schadel, Him, und Seele des Menschen und der Thiere, &c.,"
1854.)
All other circumstances being alike, the size of the brain appears to bear a general
relation to the mental power of the individual, — although many instances occur in
which this rule is not applicable. The brain of Cuvier weighed upwards of 64 oz., and
there are other recorded examples of brains belonging to men of great talent which
nearly equalled it in weight. (Emille Rousseau, " Maladie et autopsie de M. G. Cuvier,"
Lancette Fran§aise, Mai 26, 1832.) On the other hand, the brain in idiots is remark-
ably small. In three idiots, whose ages were sixteen, forty, and fifty years, Tiedemann
found the weight of their respective brains to be 19| oz., 25f oz., and 22^ oz; and
Dr. Sims records the case of a female idiot twelve years old, whose brain weighed
27 oz. Allen Thomson has found the brain of a dwarfish idiot girl seventeen years of
age to weigh 18^ oz. after preservation in alcohol.
The human brain is found to be absolutely heavier than that of all the lower
animals except the elephant and whale. The brain of the elephant, according to
Perrault, Moulins, and Sir A. Cooper, weighs between 8 and 10 Ibs. ; whilst that
of the whale was found by Rudolphi, in a specimen 75 feet long, to weigh upwards
of 5 Ibs.
The relative weight of the encephalon to the body is liable to great variation;
nevertheless, the facts to be gathered from the tables of Clendinning, Tiedemann, and
Reid, furnish this interesting general result. In a series of 81 males, the average
proportion between the weight of the brain and that of the body at the ages of twenty
years and upwards, was found to be as 1 to 36*5 ; and in a series of 82 females, to be
as 1 to 36 '46. In these cases, the deaths were the result of more or less prolonged
disease; but in six previously healthy males, who died suddenly from disease or
accident, the average proportion was 1 to 40 -8.
The proportionate weight of the brain to that of the body is much greater at birth
than at any other period of life, being, according to Tiedemann, about 1 to 5'85 in the
male, and about 1 to 6 '5 in the female. From the observations already referred to,
it further appears that the proportion diminishes gradually up to the tenth year,
being then about 1 to 14. From the tenth to the twentieth year, the relative increase
of the body is most striking, the ratio of the two being at the end of that period
about Ito30. After the twentieth year, the general average of 1 to 36'5 prevails,
with a further trifling decrease in advanced life.
Viewed in relation to the weight of his body, the brain of man may be stated
generally to be heavier than the brains of the lower animals ; but there are some
exceptions to the rule, as in the case of certain species of small birds, in the smaller
apes, and in some small rodent animals.
The attempts hitherto made to measure or estimate the relative proportions of the
different convoluted parts of the cerebrum to each other and to the degree of intelli-
gence, either more directly or by the cranioscopic methods, have as yet been attended
with little success. The more recent researches of Rudolph Wagner, which have been
farther prosecuted by his son, hold out some promise when fully carried out to afford
more definite results.
These researches had for their object to institute an accurate comparison between
the brains of certain persons of known intelligence, cultivation, and mental power,
and those of persons of an ordinary or lower grade. As examples of brains of men of
MEASUREMENT OF THE CONVOLUTIONS.
571
superior intellect, he selected those of Professor Gauss, a well-known mathematician
of eminence, and Professor Fuchs, a clinical teacher ; and as examples of brains of
ordinary persons, those of a woman of 29 and a workman named Krebs, all of which
he examined and measured with scrupulous care.
The general result of R. Wagner's researches upon these and other brains may be
stated to be as follows. 1st. Although the greatest number of brains belonging to men
of superior intellect are found to be heaviest or largest, yet there are so many instances
in which the brains of such persons have not surpassed, or have even fallen below the
average size of the brains of ordinary persons, that superiority of size cannot in the
present state of our knowledge be regarded as a constant accompaniment of superiority
of intellect, even when due regard has been paid to the comparative stature and other
circumstances of the individuals.
2nd. It would appear that, in the brains of certain persons of superior intellect,
the cerebral convolutions have been found more numerous and more deeply
divided than in those of persons of ordinary mental endowments and without culti-
vation. But numerous exceptional instances are also found of paucity of convolutions
coincident with superior intellect, which make it impossible at present to deduce any
certain conclusion with respect to the relation between the number or extent of the
convolutions and the intellectual manifestations in different persons.
The careful measurement of all the convolutions and the intervening grooves in the
four brains above mentioned has been carried out by the younger Wagner, and the
tables and results of these measurements published by him as an appendix to his
father's treatise. (Hermann Wagner, " Maasbestimmuugen der Oberflache des
Grossen Gehirns," &c., Cassel und Gb'ttingen, 1864.)
The following short table extracted from Hermann Wagner's memoir, and simplified
by the omission of small fractions and by the reduction of the measurements from
square millimetres to English square inches, may give the reader some idea of the
nature of the inquiry.
Comparative measurement of the extent of surface of the Convolutions of the
Cerebrum and its lobes.
Surface of each lobe separately.
Free and deep
surfaces of Cerebrum.
Whole
surface
of
3
1
1
'a
§1
S||
Cerebrum.
2
8
11
•la
P,
H
<n M o oo
1. Gauss
139.
70.6
59.4
68.4
112.8
228.2
341.
2. Fuchs
143.4
69.5
59.
67.5
110.7
231.3
342.
3. Woman
130.
65.
51.
66.8
107.5
209.9
317.5
4. Workman
113.2
62.3
50.5
62.
97.4
193.6
291.
WEIGHT OF THE SEVERAL PARTS OF THE ENCEPHALON.
As the result of observations made in reference to this subject, on the brains of 53
males and 34 females, between the ages of twenty -five and fifty -five, Dr. J. Reid has
given the following table : —
Males. Females. Difference,
oz. drs. oz. drs. oz. drs.
Average weight of cerebrum . . . . 43 15f 38 12 5 3|
cerebellum . . ..54 4 12£ 0 7f
„ pons and medulla oblongata 0 15f 1 0£ 0 0§
„ entire encephalon .50 3^ 44 8| 511
With these results the observations of Huschke, derived from a special examination
of the brains of 22 females, and 38 males, mainly agree.
p p 2
572 "WEIGHT OF THE BBAIN AND SPINAL COED.
From this it appears that the proportionate weight of the cerebellum to that of the
cerebrum is, in the male, as 1 to 8f, and in the female as 1 to 8j. The cerebellum
attains its maximum weight from the twenty -fifth to the fortieth year ; but the increase
in weight after the fourteenth year is shown to be relatively greater in the female than
in the male. The whole cerebellum apart from the pons and medulla is heavier in the
male ; the lateral lobes of the cerebellum are also heavier in the male. In the male
the vermiform process increases gradually from the twentieth to the fiftieth year ; in
the female it remains stationary during that period, and after the fiftieth year
diminishes rapidly.
In the new-born infant the ratio of the weight of the cerebellum to that of the whole
brain is strikingly different from that observed in the adult, being, according to
Chaussier, between 1 to 13 and 1 to 26 ; by Cruveilhier it was found to be 1 to 20.
Huschke found the weight of the cerebellum, medulla oblongata, and pons together
in the new-born infant, as compared with that of the brain, to be in the proportion of
1 to 15, and 1 to 13. In the adult, the proportions were 1 to 7, and 1 to 6.
In most mammalia, the cerebellum is found to be heavier in proportion to the
cerebrum, than it is in the human subject ; in other words, the cerebrum in man is
larger in proportion to the cerebellum.
Soemmerring pointed out the fact that the brain is larger in proportion to the
nerves connected with it in man than in the lower animals.
A comparison of the width of the cerebrum with that of the medulla oblongata
shows that the proportionate diameter of the brain to that of the medulla oblongata
is greater in man than in any animal, except the dolphin, in which creature, however,
it must be remembered that the cerebral lobes exhibit a disproportionate lateral
development. The width of the cerebrum in man, as compared with that of the
medulla oblongata at its base or broadest part, is about 7 to 1, while in many quadru-
l eds it is as 3 to 1 or even as 2 to 1.
WEIGHT OF THE SPINAL CORD.
Divested of its membranes and nerves, the spinal cord in the human subject weighs
from 1 oz. to 1| oz, and therefore its proportion to the encephalon is about 1 to 33.
Meckel states it as 1 to 40.
The disproportion between the brain and the spinal cord becomes less and less in
the descending scale of vertebrata, until at length, in cold-blooded animals, the
spinal cord becomes heavier than the brain. Thus, in the mouse, the weight of
the brain, in proportion to that of the spinal cord, is as 4 to 1 ; in the pigeon, as 3|
t) 1 ; in the newt only as § to 1 ; and in the lamprey, as ^ to 1.
In comparison with the size of the body, the spinal cord in man may be stated in
general terms to be much smaller than it is in animals. In regard to the cold-
blooded animals, to birds, and to small mammalia, this has been actually demonstrated,
but not in reference to the larger mammalia.
R. Wagner states, as follows, the proportion of the weight of the spinal marrow
taken as 1 to the encephalon and its parts —
a, to the nerve roots
b, to the medulla and pons
c, to the cerebellum
d, to the cerebrum
e, to the encephalon
1 : 0-53
1 : 1*
1 : 5-18
1 : 42-78
1 : 48-96
SPECIFIC GRAVITY OF THE ENCEPHALON.
The specific gravity of different parts of the encephalon has of late attracted some
attention from its having been observed that it varies to some extent in different
kinds of disease. From the researches of Bucknill, Sankey, Aitken, and Peacock, it
appears that the average specific gravity of the whole encephalon is about 1036, that
of the grey matter 1034, and that of the white 1040. There are also considerable
differences in the specific gravity of some of the internal parts. (William Aitken,
" The Science and Practice of Medicine," 1865, vol. 2, p. 265 : J. C. Bucknill in " The
Lancet," 1852 : Sankey, in the "Brit, and For. Med. Chir. Eeview," 1853 : Thos. B.
Peacock, in the Trans, of the Patliol. Soc. of London, 1861-2.)
PRIMITIVE CEREBRO-SPIXAL CAXAL.
573
DEVELOPMENT OF THE CEREBRO-SPINAL AXIS.
The cerebro-spinal axis is formed from a superficial deposit of blastema, which
occupies the whole width of the dorsal furrow, that elongated depression whose
margins come together to complete the walls of the cranio-vertebral cavity (p. 15).
This layer of blastema increases in
thickness in each lateral half, while in Fig. 386.
A.
Fig. 386. — PRIMITIVE FORM OF THE
CEREBRO-SPINAL Axis IN THE EM-
BRYO OF THE BIRD. Magnified.
A and B (from Reichert) outlines of
the dorsal aspect of the embryo bird at
twenty-four and thirty-six hours of in-
cubation. In A, the sides of the pri-
mitive groove have united to a great
extent and converted it into a canal,
dilated at the cephalic extremity, 2 ;
6, the cephalic fold of the germinal
membrane ; 8, the primordial vertebral
masses ; 9, the unclosed lumbar part
of the vertebral groove. In B, 10, 11,
and 12 indicate the partial division of the
cephalic portion of the tube into the
three primary vesicles ; 13, the rudi-
ment of the eye ; 14, that of the ear.
C, represents a transverse section of
the body of the embryo previous to the
closure of the vertebral groove. 1,
chorda dorsalis; 2, primitive vertebral
groove ; 2 to 3, medullary plates con-
tinuous at 3, with 4, the corneous layer
of the blastoderm ; 5, the ventral plates
of the middle layer ; 6, the lowest or epi-
thelial layer; 7, the primordial vertebral
Fig. 387.
Fig. 387. — TRANSVERSE SECTION OF THE CERVICAL
PART OF THE SPINAL CORD OF A HUMAN EMBRYO OF
Six WEEKS (from Kolliker). *£
This and the following figure are only sketched, the
white matter and a part of the grey not being shaded
in. c, central canal ; e, its epithelial lining ; at e
(inferiorly), the part which becomes the anterior com-
missure ; at e' (superiorly) the part which becomes
the posterior commissure ; a, the white substance of
the anterior columns, beginning to be separated from
the grey matter of the interior, and extending round
into the lateral column, where it is crossed by the
line from g, which points to the grey substance ; pt
posterior column ; a, r, anterior roots ; p, r, posterior
roots.
the middle line — the primitive groove — it remains
thin and depressed. The thin middle portion is
that which forms in the spinal cord the anterior commissure. At the same time
that the walls of the cranio-vertebral cavity are completed behind, the lateral margins
of the cerebro-spinal axis are also bent backwards and meet together, so as to form
a tube ; and this line of junction is the rudiment, in the spinal cord, of the posterior
commissure, while the space within the cylinder is the central canal. The closure of
the canal first takes place in the cervical region, and subsequently proceeds thence
backwards in the dorsal, lumbar, and sacral regions.
574
DEVELOPMENT OF THE CEREBRO-SPINAL AXIS.
The SPINAL CORD has been found by Kblliker already in the form of a cylinder in
the cervical region of an embryo four weeks old. Ununited borders have been seen
by Tiedemann in the ninth week towards the lower end of the cord, the perfect closing
of the furrow being delayed in that part, which is slightly enlarged and presents a
longitudinal median slit, analogous to the rhomboidal sinus in birds.
The anterior fissure of the cord is developed very early, and contains even at first a
process of the pia mater.
The cervical and lumbar enlargements opposite the attachments of the brachial and
crural nerves, appear at the end of the third month : in these situations the central
canal, at that time not filled up, is somewhat larger than elsewhere.
Fig. 388.
Fig. 388. — TRANSVERSE SECTION OF HALF
THE CARTILAGINOUS VERTEBRAL COLUMN
AND THE SPINAL CORD IN THE CERVICAL
PART OF A HUMAN EMBRYO OF FROM
NINE TO TEN WEEKS ^from Kolliker). J^
c, central canal lined with epithelium ;
a, anterior column; p, posterior column;
p', band of Goll ; g, ganglion of the
posterior root ; p r, posterior root ; a r,
anterior root passing over the ganglion ;
dm, dura matral sheath, omitted near p r,
to show the posterior roots ; b, body of
the vertebra ; c h, chorda dorsalis ; n a,
neural arch of the vertebra.
At first the cord occupies the whole
length of the vertebral canal, so that
there is no cauda equina. In the fourth
month the vertebrae begin to grow more
rapidly than the cord, and the latter
seems as it were to have retired up into
the canal, and the elongation of the roots
of the nerves which gives rise to the cauda
equina is commenced. At the ninth
month, the lower end of the cord is
opposite the third lumbar vertebra.
In textual composition the spinal cord consists at first, after the completion of its
cylindrical form, entirely of uniform-looking cells. These separate into two layers,
the inner of which forms the epithelium and surrounding connective tissue, or neu-
roglia of the central canal, while the outer forms the grey substance of the cord. The
white substance appears later than the grey, forming a layer external to it, and sepa-
rated from an early period into an antero-lateral and a posterior column on each side.
At a somewhat later period the white mass of these columns, increasing greatly in
size, gives rise to the formation and gradually increasing depth of the anterior and
posterior median fissures. At the same time, however, the lateral masses of grey
substance also undergo extension in the parts named the cornua. It would appear
that the integral nerve-fibres are at first developed from radiating processes which
proceed from the cells of the grey substance. (Kolliker, Entwicklungsgeschichte ;
Lockhart Clarke, in the Phil. Trans. 1862 ; Bidder und Kupfer, Untersuch. iib. d.
Euckenmark, Leipz., 1857.)
It may also be mentioned that, according to Remak and Kb'lliker, the roots of the
spinal nerves and the ganglion are at first unconnected with the cord. The mass of
blastema forming the ganglion first becomes apparent, and from this the posterior root
seems to gro w towards, and later to become attached to, the cord ; while the anterior roots
seem to extend outwards from the cord and to unite themselves later with the nerve.
The central canal is at first nearly cylindrical ; it then becomes flattened at the
sides, projecting deeply backwards and forwards. Between the eighth and tenth
weeks it is greatly narrowed, and subsequently, being more and more confined to
the centre, it ultimately diminishes to a small tube. The epithelial cells which line
it from the first are long or columnar, and they retain this form in the adult.
FORMATION OF THE EXCEPHALOX.
THE EXCEPHALOX.
575
The brain is originally not to be distinguished from the spinal cord, being in fact
the anterior portion of the medullary tube. It is soon altered in form, however, by
the expansion of its walls in certain parts, while others enlarge in a less degree, and it
then presents the appearance of a series of three cerebral vesicles, usually designated
by embryologists the primary cerebral vesicles.
Fig. 389. — SKETCHES OF THE PRIMITIVE PARTS
OF THE HUMAN BRAIN (from Kolliker).
Fig. 389.
1, 2, and 3 are from a human embryo of
about seven weeks. 1, view of the whole
embryo from behind, the brain and spinal cord
exposed ; 2, the posterior, and 3, the lateral
view of the brain removed from the body ; A,
the anterior part of the first primary vesicle
or cerebral hemisphere (prosencephalon) ; z,
the posterior part of the same vesicle (dien-
cephalon) ; i', the lower part of the same ; m,
the middle primary vesicle (inesencephalon) ; e,
the cerebellum or upper part of the third
primary vesicle (epencephalon) ; m o, the lower
part of the third primary vesicle or medulla
oblongata. The figure 3 illustrates the several
curves which take place in the development
of the parts from the primitive medullary tube. In 4, a lateral vie* is given of the
brain of a human embryo of three months : the enlargement of the cerebral hemisphere
has covered in the optic thalami, leaving the tubercula quadrigemina, m, apparent.
The changes which take place in the growth of the brain were first elaborately
described by Tiedemann ; they have been investigated by Von Baer, Bischoff, Remak,
Kolliker, and others, and have recently received additional elucidation from the
researches of Reichert. (Tiedemann, " Anatomic und Bildungsgeschichte des
Gehirns," Nuremberg, 1816 ; Reichert, " Bail des Menschlichen Gehirns," Leipzig.
1861 ; F. Schmidt, " Beitrage z. Entwick. des Gehirns," in Zeitschr. f. Wissen. Zool.
1862 ; Kolliker, Entwicklungsgeschichte, 1861.)
DEVELOPMENT OP THE PRIMARY VESICLES. — The anterior or first vesicle, is the part
from which are developed the third ventricle, the optic thalami, the corpora striata,
and the cerebral hemispheres.
The middle or second vesicle, forms the corpora quadrigemina above, and the crura
cerebri below, — its cavity remaining as the Sylvian aqueduct.
The posterior or third vesicle, continues incomplete above for some time, in so far as
relates to its nervous substance. At length its anterior portion is closed over and forms
the cerebellum above, whilst in its under part the pons Varolii is produced. The
posterior portion, on the other hand, continues open on its dorsal aspect, and forms the
medulla oblongata and fourth ventricle.
Fig. 390. — LONGITUDINAL SECTION OF THE
CRANIAL CAVITY OF THE HUMAN EMBRYO AT
FOUR WEEKS (from Kolliker). —•
1, 2, 3, 4, and .*>, mark the depressions in
the cranial wall which contain respectively the
cerebral hemispheres, the thalarai, the corpora
quadrigemina, the cerebellum, an,l the medulla
oblongata; in 1, at o, the depression of the eye,
and at o', the optic nerve is seen ; in 5, at a u,
the primary auditory vesicle ; p, process from
the phai'ynx, supposed by llathke to be con-
nected with the formation of the pituitary
body or hypophysis cerebri ; t, t, middle
cranial septum or teutorium.
These three vesicles, at first arranged in a straight line, one before the other, soon
576
DEVELOPMENT OF THE CEREBRO-SPINAL AXIS.
alter their position, in correspondence with the curving downwards of the cephalic
end of the embryo. Thus, at the seventh week there is an angular bend forwards
between the hindmost vesicle and the rudimentary spinal cord, the projecting angle
(backwards) being named the cervical tuberosity. Another bend, but in the opposite
direction, exists between that part of the third vesicle which forms the medulla
oblongata, and that which gives rise to the cerebellum. Lastly, a third angle is pro-
duced by a bend forwards and downwards in the region of the middle vesicle, from
which the corpora quadrigemina are developed, and which forms, at this period, the
highest part of the encephalon ; whilst the anterior, or first vesicle, is bent nearly at a
right angle downwards.
Fig. 391. Fig. 391. — SKETCHES OF THE EARLY
FORM OF THE PARTS OF THE
CEREBRO- SPINAL Axis IN THE
HUMAN EMBRYO (after Tiede-
mann).
A, at the seventh week, lateral
view ; 1, spinal cord ; 2, medulla
oblongata ; 3, cerebellum ; 4, mid-
dle vesicle or corpora quadrigemina;
5, 6, 7, first vesicle. B, at the
ninth week, posterior view ; 1,
medulla oblongata ; 2, cerebellum ;
3, corpora quadrigemina ; 4, 5, tha-
lami optici and cerebral hemispheres.
C and D, lateral and posterior views
of the brain of the human embryo
at twelve weeks, a, cerebrum ; b,
corpora quadrigemina ; c, cere-
bellum ; d, medulla oblongata ; the
thalami are now covered by the
enlarged hemispheres. E, posterior
view of the same brain dissected to
show the deeper parts. 1, medulla
oblongata ; 2, cerebellum ; 3, cor-
pora quadrigemina ; 4, thalami
optici ; 5, the hemisphere turned
aside ; 6, the corpus striatum em-
bedded in the hemisphere ; 7, the
commencement of the corpus cal-
losum. F, the inner side of the
right half of the same brain sepa-
rated by a vertical median section,
showing the central or ventricular
cavity. 1, 2, the spinal cord and
medulla oblongata, still hollow ; 3,
bend at which the pons Varolii is
formed ; 4, cerebellum ; 5, lamina
(superior cerebellar peduncles) passing up to the corpora quadrigemina ; 6, crura cerebri ;
7, corpora quadrigemina, still hollow ; 8, third ventricle ; 9, infundibulum ; 10, thata-
mus, now solid ; 11, optic nerve ; 12, cleft leading into the lateral ventricle ; 13, com-
mencing corpus callosum.
F
At an early period of the development of the brain, the anterior primary vesicle
„ undergoes a peculiar change, by which two sets of parts are originated, the first of
which corresponds to the cerebral hemispheres, the second to the thalami optici ; the
middle vesicle, remaining single, gives rise to the corpora quadrigemina ; and the
posterior vesicle, like the first, but at a somewhat later period, serves as the basis of
the rudiments of two parts, viz., the cerebellum and the medulla oblongata. Thus,
out of the three primary vesicles five fundamental parts of the encephalon are
formed.
The following tabular statement may serve as a synoptical view of the relation
PARTS DERIVED FROM PRIMARY CEREBRAL VESICLES. 577
subsisting between the primary encephalic vesicles, the five fundamental parts, and
the principal permanent structures of the brain : — •
( Cerebral Hemispheres, Corpus Callosum,
/•I. Prosencephalon. * I Corpora Striata, Fornix, Lateral Yen-
I. Anterior primary Vesicle J ' tricles' Olfa'tory nerve.
U Diencephalon.
II. Middle primary Vesicle, 3. Mesencephalon.
. ,-, , , ( Cerebellum, Pons Varolii, anterior part of
f 4- Epencephalon. J th(J Fom^ Ventricle>
III. Posterior primary Vesicle, •<
I , ,, . , . ( Medulla Oblongata, Fourth Ventricle, Au-
lo. Metencephalon. { ditory nerve *
At a later period of development, the anterior part of the first vesicle, which, as
stated above, represents the cerebral hemispheres, increases greatly in size upwards
and backwards, and gradually covers the parts situated behind it ; first the thalami,
then the corpora quadrigemina, and lastly the cerebellum.
On laying open the rudimentary encephalon, two tracts of nervous matter are seen
to be prolonged upwards from the spinal cord upon the floor of the cephalic vesicles ;
these tracts, which are doubtless connected with the anterior and lateral parts of the
cord, are the rudiments of the crura cerebri and corresponding columns of the
medulla oblongata.
FARTHER DEVELOPMENT OF THE PRIMARY VESICLES.— The third vesicle. — The poste-
rior portion of this vesicle, corresponding with the medulla oblongata, is never closed
above by nervous matter. The open part of the medullary tube constitutes the'floor
of. the fourth ventricle, which communicates below with the canal of the spinal cord,
at the place where the calamus scriptorius is eventually formed.
The three constituent parts of the medulla oblongata begin to be distinguished about
the third month ; first the restiform bodies, which are connected with the commencing
cerebellum, and afterwards the anterior pyramids and olives. The anterior pyramids
become prominent on the surface and distinctly denned in the fifth month ; and by
this time also their decussation is evident. The olivary fasciculi are early distin-
guishable, but the proper olivary body, or tubercle, does not appear till about the
sixth month. The fasciolae, cinerece of the fourth ventricle can be seen at the fourth
or fifth month, but the white strice not until after birth.
The anterior part of the third vesicle is soon closed above by nervous substance,
and forms the commencing cerebellum. This part exists about the end of the second
month, as a delicate medullary lamina, forming an arch behind the corpora quadri-
gemina across the widely open primitive medullary tube.
According to Bischoff, the cerebellum does not commence, as was previously sup-
posed, by two lateral plates which grow up and meet each other in the middle line ; but
a continuous deposit of nervous substance takes place across this part of the medullary
tube, and closes it in at once. This layer of nervous matter, which is soon connected
with the corpora restiformia, or inferior peduncles, increases gradually up to the fourth
month, at which time there may be seen on its under surface the commencing corpus
dentatum. In the fifth month a division into five lobes has taken place ; at the sixth,
these lobes send out folia, which are at first simple, but afterwards become subdivided.
Moreover, the hemispheres of the cerebellum are now relatively larger than its
median portion, or worm. In the seventh month the organ is more complete,
and the flocculus and posterior velum, with the other parts of the inferior vermiform
process, are now distinguishable, except the amygdala, which are later in their
appearance.
Of the peduncles of the cerebellum, the inferior pair (corpora restiformia) are the
first seen — viz., about the third month ; the middle peduncles are perceptible in the
fourth month ; and at the fifth, the superior peduncles and the Vieussenian valve.
* This and the four following terms are adopted as applicable to the principal secondary
divisions of the primordial medullary tube, and as corresponding to the commonly received
names of the German embryologists, viz., Vorderhirn, Zwischenhirn, Mittelhirn, Hinter-
hirn, and Nachhirn ; or their less used English translations, viz., forebrain, interbrain,
midbrain, hindbrain, and afterbrain.
578
DEVELOPMENT OF THE CEREBRO-SPINAL AXIS.
The pons Varolii is formed, as it were, by the fibres from the hemispheres of the
cerebellum embracing the pyramidal and olivary fasciculi of the medulla oblongata.
According to Baer, the bend which takes place at this part of the encephalon
thrusts down a mass of nervous substance before any fibres can be seen ; and in
this substance transverse fibres, continuous with those of the cerebellum, are after-
wards developed. From its relation to the cerebellar hemispheres the pon.s keeps
pace with them in its growth ; and, in conformity with this relation, its transverse
fibres are few, or entirely wanting, in those animals in which there is a corresponding
deficiency or absence of the lateral parts of the cerebellum.
Fig. 392. Fig. 392 A. — BRAIN AND SPINAL CORD EXPOSED FROM BEHIND IN
^ A FOSTUS OF THREE MONTHS (from Kolliker).
h, the hemispheres ; m, the mesencephalic vesicle or corpora
quadrigemina ; c, the cerebellum ; below this are the medulla
oblongata, mo, and fourth ventricle, with remains of the membrana
obturatoria. The spinal cord, s, extends to the lower end of the
sacral canal and presents the brachial and crural enlargements.
Fig. 392 B. — UPPER VIEW OF THE BRAIN OF A THREE MONTHS'
FffiTUS, IN WHICH THE HEMISPHERES HAVE BEEN DIVIDED AND
TURNED ASIDE, AND THE VESICLE OF THE MESENCEPHALON (CoR-
PORA QDABRIGEMINA) OPENED (from Kolliker).
/, anterior part of the great arch of the hemispheres over the
cerebral fissure ; f, posterior part descending into the cornu am-
monis ; cs, corpus striatum ; th, thalaraus opticus ; m, in the
floor of the opened vesicle of the mesencephalon, which is still
hollow.
The second, or middle vesicle. — The corpora quadrigemina
are formed in the upper part of the middle cephalic vesicle ;
the hollow in the interior of which communicates with those
of the first and third vesicles. The corpora quadrigemina, in
the early condition of the human embryo, are of great propor-
tionate volume, in harmony with what is seen in the lower
vertebrata : but subsequently they do not grow so fast as the
anterior parts of the encephalon, and are therefore soon
overlaid by the cerebral hemispheres, which at the sixth month
cover them in completely. Moreover, they become gradually
solid by the deposition of matter within them ; and as, in the
meantime, the cerebral peduncles are increasing rapidly in size
in the floor of this middle cephalic vesicle, the cavity in its
interior is quickly filled up, with the exception of the narrow
passage named the Sylvian aqueduct. The fillet is distinguish-
able in the fourth month. The corpora quadrigemina of the
two sides are not marked off from each other by a vertical
median groove until about the sixth month ; and the trans-
verse depression separating the anterior and posterior pairs'
is first seen about the seventh month of intra-uterine life.
The first, or anterior vesicle. — This vesicle, very soon after its formation, exhibits
two lateral outgrowths— the optic vesicles, — destined to form the fundamental parts of
the organs of vision. Each of these soon becomes separated from the parent vesicle
by a constricted part, which forms the optic nerve and tract. The first vesicle has
usually been described as dividing into two portions — viz., a posterior, which is
developed into the optic thalami and third ventricle, and an anterior, which forms the
principal mass of the cerebral hemispheres, including the corpora striata. Reichert,
however, has pointed out that the hemispheres and corpora striata are developed
from the sides of the fore part of the vesicle, and become distinguished from it by a
constriction similarly as the optic vesicles had previously been, and that there is left
between the hemisphere-vesicles of opposite sides a wedge-shaped interval, which forms
the third ventricle. He points out that the terminal extremity of the cerebro-spinal
tube is at the tip of this wedge, and is placed immediately in front of the optic
commissure, at the lamina cinerea ; and that therefore the infundibulum is not that
PINEAL GLAND.— OPTIC TEAL AMI.
579
Fig. 393.
extremity, as had been previously supposed by Baer, but is an expansion of the vesicle
downwards, in similar fashion as there is an expansion of it upwards in the region of
the pineal body.
The pituitary body was asserted by Rathke to be derived
from a prolongation upwards of the mucous membrane of the
pharynx into the base of the skull between the trabeculse. It
appears, however, from the researches of Reichert and Bidder,
that the base of the skull is never imperfect in this region.
Reichert suggested that the pituitary body might be derived
from the extremity of the chorda dorsalis, but is now rather
inclined to think that it is a development of the pia mater.
Fig. 393. — BRAIN AND SPINAL CORD OP A FOSTUS OF POUR
MONTHS, SEEN FROM BEHIND (from Kolliker).
k, hemispheres of the cerebrum ; m, corpora quadrigemina
or mesencephalon ; c, cerebellum ; m o, medulla oblongata, the
fourth ventricle being overlapped by the cerebellum j s, s, the
spiual cord with its brachial and crural enlargements.
The pineal gland, according to Baer, is developed from
the back part of the thalami, where those bodies continue
joined together ; but it is suggested by Bischoff that its
development may be rather connected with the pia mater.
It was not seen by Tiedemann until the fourth month ; sub-
sequently its growth is very slow ; and it at first contains no
gritty deposit : this, however, was found by Sb'mmerring at
birth.
The two optic thalami, formed from the posterior part of
the anterior vesicle, consist at first of a single hollow sac of
nervous matter, the cavity of which communicates in front
with the interior of the commencing cerebral hemispheres, and
behind with that of the middle cephalic vesicle (corpora
quadrigemina). Soon, however, by means of a deposit taking place in their interior
Fig. 394.
Fig. 394.— SEMIDIAGRAMMATIC VIEWS OP THE INNER SURFACE OP THE RIGHT CEREBRAL
HEMISPHERE OP THE FCETAL BKAIN AT VARIOUS STAGES OP DEVELOPMENT (from
Schmidt).
1, 2, and 3, are from foetuses of the respective ages of eight, ten, and sixteen weeks ;
4, from a foetus of six months, a, lamina terminalis or part of the first primary vesicle
which adheres to the sella turcica ; 6, section of the cerebral peduncle as it passes into
the thalamus and corpus striatum ; the arched line which surrounds this bounds the great
cerebral fissure ; c, anterior part of the fornix and the septum lucidum ; d, inner part
of the arch of the cerebrum, afterwards the hippocampus major and posterior part of the
fornix ; e, corpus callosum, very short in 3, elongated backwards in 4 ; in 4, /, the
superior marginal convolution; /', fronto-parietal fissure ; g, gyrus fornicatus ; p', the
internal vertical fissure descending to meet the fissure of the hippocampus ; I, olfactory
bulb ; F, P, 0, T, frontal, parietal, occipital and temporal lobes.
580 DEVELOPMENT OF THE CEREBRO-SPINAL AXIS.
behind, below, and at the sides, the thalami become solid, and at the same time a
cleft or fissure appears between them above, and penetrates down to the internal
cavity, which continues open at the back part opposite the entrance of the
Sylvian aqueduct. This cleft or fissure is the third ventricle. Behind, the two
thalami continue united by the posterior commissure, which is distinguishable
about the end of the third month, and also by the peduncles of the pineal gland. The
soft commissure could not be detected by Tiedemann until the ninth month ; but its
apparent absence at earlier dates may perhaps be attributed to the effects of laceration.
At an early period the optic tracts may be recognised as hollow prolongations from
the outer part of the wall of the thalami while they are still vesicular. At the fourth
month these tracts are distinctly formed.
The hemisphere-vesicle becomes divisible into two parts : one of these is the part
which from the interior appears as the corpus striatum, and from the exterior as the
island of Reil, or central lobe; the other forms the expanded or covering portion
of the hemisphere, and is designated by Reichert the mantle. The aperture existing
at the constricted neck of the hemisphere vesicle, Schmidt and Reichert have recognised
as the foramen of Monro.
The corpora striata, it will be observed, have a very different origin from the optic
thalami ; for, while the optic thalami are formed by thickening of the circumferential
wall of a part of the first cerebral vesicle, and thus correspond in their origin
with all the parts of the encephalon behind them, which are likewise derived from
portions of the cerebro-spinal tube, the corpora striata appear as thickenings of the
floor of the hemisphere-vesicles, which are lateral offshoots from the original cerebro-
spinal tube. On this account, Reichert considers the brain primarily divisible into the
stem, which comprises the whole encephalon forwards to the tsenia semicircularis, and
the hemisphere-vesicles, which include the corpora striata and hemispheres.
The cerebral hemispheres enlarging, and having their walls increased in thickness
form, during the fourth month (Tiedemann), two smooth shell-like lamellee, which
include the cavities afterwards named the lateral ventricles, and the parts contained
within them. Following out the subsequent changes affecting the exterior of the
cerebral hemispheres, it is found that about the fourth month the first traces of some
of the convolutions appear, the intermediate sulci commencing only as very slight
Fig. 395. — THE SURFACE OF THE F<ETAL BRAIN AT Six MONTHS (from R. Wagner).
This figure is intended to show the commencement of the formation of the principal
fissures and convolutions. A, from above ; B, from the left side. F, frontal lobe ; P,
parietal ; 0, occipital ; T, temporal ; a, a, a, slight appearance of the several frontal
convolutions ; s, the Sylvian fissure ; s', its anterior division ; within it, C, the central
lobe or convolutions of the island ; r} fissure of Rolando ; p, the vertical fissure (external
part) ; t} the parallel fissure.
depressions on the hitherto smooth surface. Though the hemispheres continue to
grow quickly upwards and backwards, the convolutions at first become distinct by
HEMISPHERES.— CORPUS CALLOSUM.
581
comparatively slow degrees ; but towards the seventh and eighth months they are
developed with great rapidity, and, at the beginning of the last month of intra-uterine
life, all the principal ones are marked out.
The S'/lvian fissure, which afterwards separates the anterior from the middle lobe
of each hemisphere, begins as a depression or cleft between them about the fourth
month, and, after the gre-it longitudinal, is the first of the fissures to make its
appearance. It is followed by the fissure of Rolando, and the vertical fissure, and
somewhat later by the internal fronto -parietal fissure. After this, the various sub-
ordinate fissures dividing the convolutions gradually make their appearance. By the
end of the third month the hemispheres have extended so far backwards as to cover
the thalami ; at the fourth they reach the corpora quadrigemina ; at the sixth they
cover those bodies and great part of the cerebellum, beyond which they project still
further backwards by the end of the seventh month.
During the growth of the hemisphere the aperture of the foramen of Monro is
extended backwards ; the arched margin of this opening is curved downwards at
its extremities, and forms anteriorly the fornix, and posteriorly the corpus fimbriatum
and hippocampus major ; above the margin a part of the wall of each hemisphere
comes into contact with its fellow, and in the lower part forms the septum lucidum,
while above this the hemispheres are united by the development of the great
commissure, the corpus callosum.
The corpus callosum is described by Tiedemann as being first seen about the end of
the third month, as a narrow vertical band, extending across between the forepart of
the two hemispheres, and subsequently growing backwards. With this view the
observations of Schmidt coincide. Reichert, however, maintains that the commissural
structure seen at the forepart of the hemispheres is the anterior white commissure,
and that the corpus callosum appears in its whole extent at once.
The corpora albicantia at first form a single mass : so also do the anterior pillars
of the fornix, which are distinguished before the posterior pillars. The posterior
pillars are not seen until the fourth or fifth month. At that period the hippocampus
minor is also discernible.
Fig. 396. — VIEW OP THE INNER Fig. 396.
SURFACE OF THE RIGHT HALF
OF THE FCETAL BRAIN OF ABOUT
six MONTHS (from Reichert).
F, frontal lobe; P, parietal;
0, occipital; T, temporal; I,
olfactory bulb ; II, right optic
nerve ; fp, fronto-parietal fissure ;
p, vertical fissure ; />', inter-
nal vertical fissure ; Ti, hippo-
campal fissure ; g, gyrus forni-
catus ; c, c, corpus callosum ;
s, septum lucidum ; f, placed
between the middle commissure
and the foramen of Monro ;
v, in the upper part of the
third ventricle immediately below
the velum interpositum and for-
nix : v', in the back part of the
third ventricle below the pineal gland, and pointing by a line to the aqueduct of Sylvius ;
v", in the lower part of the third ventricle above the infundibulum ; r, recessus pinealis
passing backwards from the tela choroidea; p v, pons Varolii; Ce, cerebellum.
MEMBRANES OF THE ENCEPHALON.
It is remarked by Bischoff, that the pia mater and arachnoid are formed by the
separation of the outer layer of the primitive cephalic mass ; and thus that the pia
mater does not send inwards processes into the fissures or sulci, nor into the ventri-
cular cavities ; but that every part of this vascular membrane, including the choroid
plexuses and velum interpositum, is formed in its proper position in connection
Avith the nervous matter. The dura mater, on the other hand, is developed from the
inner surface of the dorsal plates.
582
THE CRANIAL NERVES.
The pia mater and dura mater have both been detected about the seventh or
eighth week, at which period the tentorium cerebelli exists. At the third month
the falx cerebri, with the longitudinal and lateral sinuses, are perceptible; and the
choroid plexuses of both the lateral and fourth ventricles are distinguishable. No
trace of arachnoid, however, can be seen until the fifth month.
II. THE CEREBRO-SPINAL NERVES.
The nerves directly connected with the great cerebro-spinal centre
constitute a series of symmetrical pairs, the number of which has been
variously estimated from forty to forty- three. Of these nerves, when esti-
mated at the smaller number, nine issue from the cranium through different
foramina or apertures in its base, and are thence strictly named cranial.
The teuth nerve passes out between the occipital bone and the first vertebra,
and the remaining thirty nerves all issue below the corresponding vertebral
pieces of the spine. To the whole series of thirty-one nerves the name of
spinal is usually given.
A.— CRANIAL NERVES.
The cranial nerve?, besides being named numerically, according to the
relative position of the apertures for their exit from the cranium, have
likewise been distinguished by other names, according to the place or
mode of their distribution, and according to their functions or other circum-
stances.
The number of the cranial nerves has been variously stated as nine or as
twelve by different anatomists ; the difference consisting mainly in this,
that, under one system, the nerves which enter the internal auditory
meatus, and those which pass through the jugular foramen, are in each
case considered a single pair (seventh and eighth) divisible into parts ;
while under another system each of the nerves is held to constitute a
distinct pair. The following table presents a synoptical view of the cranial
nerves under these two modes of enumeration, as in the respective systems
of Willis and of Sommerring.
Olfactory nerves.
Optic.
Oculo-motor.
Pathetic or trochlear.
Trifacial or trigeminal.
Abducent ocular.
Facial motor.
Auditory.
Glosso-pharyngeal.
Pneumo-gastric.
Spinal accessory.
Hypoglossal or lingual motor.
The arrangement of Sommerring is the preferable one, as being the
simplest and most natural ; for each of the parts included in the seventh
and eighth pairs of Willis is really a distinct nerve. But as the plan of
Willis is still in more general use, it will most conveniently be followed
here. The cranial nerves will therefore, when not otherwise designated, be
referred to as consisting of nine pairs.
* Willis described the glosso-pharyngeal nerve as a branch of the vagus, and included
the suboccipital nerve as a tenth among the cranial nerves.
WILLIS*
SCEMMERIUNQ.
First pair of nerves
First pair of nerves
Second „
Second
} ,
Third
Third
1 •
Fourth
Fourth
> •
Fifth „
Fifth
Sixth „
Sixth
i •
( nervusdurus
Seventh
1 •
Seventh w | n< mollis .
Eighth
> .
in. vagus
( Ninth
, .
\ Tenth
t .
accessorius.
Eleventh
, .
Ninth „
Twelfth
> •
ORIGIN OF THE "CRANIAL NERVES.
£83
CONNECTIONS OF THE CRANIAL NERVES WITH THE ENCEPHALON.
The roots of the cranial nerves may be traced for some depth into the
substance of the encephalon, a circumstance which has led to the distinction
of the deep or real origin, and the superficial or apparent origin, by which
latter is understood the place at which the nerve appears to be attached to
the surface of the encephalon. The superficial origin of these nerves is
quite obvious, but their deeper connection is, in most cases, still a matter
of some uncertainty.
Fig. 397.— VIEW FROM
BELOW OF THE CONNEC-
TION OF THE PRINCIPAL
NERVES WITH THE
BRAIN.
The full description of
this figure will be found
at p. 538. The following
references apply to the
roots of the nerves : I',
the right olfactory tract
divided near its middle ;
II, the left optic nerve
springing from the com-
missure which is con-
cealed by the pituitary
body ; II', the right optic
tract; the left tract is
seen passing back into
i and e, the internal and
external corpora genicu-
lata ; III, the left oculo-
motor nerve ; IV, the
trochlear ; V, V, the
large roots of the tri-
facial nerves ; + + , the
lesser roots, the -r of the
right side is placed on
the Grasserian ganglion ;
1, the ophthalmic ; 2, the
superior maxillary, and
3, the inferior maxillary
nerves ; VI, the left ab-
ducent nerve ; VII, a, &,
the facial and auditory
nerves ; a, VIII, 6, the
glosso-pharyngeal, pneu-
mo -gastric, and spinal ac-
cessory nerves ; IX, the
right hypoglossal nerve ;
at o, on the left side, the
rootlets are seen cut-
short ; C I, the left sub-
occipital or first cervical
nerve.
Fig. 397.
Ci
cL ca
1. The first or olfactory nerve, as it is usually described, small in man in
comparison with animals, lies on the under surface of the anterior lobe of the
cerebrum to the outer side of the longitudinal median fissure, lodged in a
sulcus between two straight convolutions. Unlike other nerves, it consists
of a large proportion of grey matter mixed with white fibres, and indeed
584 THE CRANIAL NERVES.
agrees closely in structure with the cerebral substance. It swells into an oval
enlargement, the olfactory bulb, in front, which also contains much grey
matter, and from this part small soft nerves descend through the cribriform
plate into the nose. When traced backwards, it is found to be spread out
and attached behind to the under surface of the anterior lobe by means of
three roots, named external, middle, and internal, which pass in different
directions. The bulbous part is therefore rather to be regarded as an
olfactory lobe of the cerebrum than as a part of a true nerve, while the
white part prolonged backwards into the brain, together with its so-called
roots, may be termed the olfactory tract.
The external or long root consists of a band of medullary fibres, which
passes, in the form of a white streak, outwards and backwards along the
anterior margin of the perforated space, towards the posterior border of the
Sylvian fissure, where it may be followed into the substance of the cere-
brum. Its further connections are doubtful, but it has been stated that its
fibres have been traced to the following parts, viz., the convolutions of the
island of Reil, the anterior commissure, and the superficial layer of the
optic thalamus (Valentin).
The middle or grey root is of a pyramidal shape, and consists of grey
matter on the surface, which is prolonged from the adjacent part of the
anterior lobe and perforated space. Within it there are white fibres, which
have been traced to the corpus striatum.
The internal root (short root, Scarpa), which cannot always be demon-
strated, is composed of white fibres which may be traced from the inner and
posterior part of the anterior lobe, where they are said by Foville to be
connected with the longitudinal fibres of the gyrus fornicatus.
The question whether the olfactory bulbs ought to be considered as nerves or as
cerebral lobes is, if tested by reference to the history of development, not so simple
as might at first appear. It is in favour of their being regarded as lobes, that in
the lower vertebrate animals the olfactory bulbs are generally recognised by com-
parative anatomists as additional encephalic lobes, and that in most mammals they
are much larger proportionally than in man, and frequently contain a cavity or
ventricle in their interior, and further that in their minute structure they nearly
agree with the cerebrum ; but, as it is known that in the first development of the
eye the peripheral part or retina, as well as the rest of the optic nerve, is originally
formed by the extension of a hollow vesicle from the first foetal encephalic compart-
ment, so in the case of the olfactory nerve, although the peripheral or distributed part
is of separate origin from the olfactory bulb, the latter part is comparable in its
origin with the optic vesicle.
2. The second pair or optic nerves of the two sides meet each other at
the optic commissure (chiasma), where they partially decussate. From this
point they may be traced backwards round the crura cerebri, under the
name of the optic tracts.
Each optic tract aiises from the optic thalamus, the corpora quadri-
gemina, and the corpora geniculata. As it leaves the under part of the
thalamus, it makes a sudden bend forwards and then runs obliquely across
the under surface of the cerebral peduncle, in the form of a flattened band,
which is attached by its anterior surface to the peduncle ; after this, becoming
more nearly cylindrical, it adheres to the tuber cinereum, from which and, as
stated by Yicq-d'Azyr, from the lamina cinerea it is said to receive an
accession of fibres, and thus reaches the optic commissure.
In the commissure the nerve-fibres of the two sides undergo a partial de-
cussation. The outer fibres of each tract continue onwards to the eye of the
ROOTS OF THE CEAXIAL NERVES.— OPTIC.
585
same side : the inner fibres cross over to the opposite side ; and fibres have
been described as running from one optic tract to the other along the
posterior part of the commissure, while others pass between the two optic
nerves in its anterior part (Mayo).
In front of the commissure, the nerve enters the foramen opticum,
receiving a sheath from the dura mater and acquiring greater firmness.
Fig. 398.
Fig. 398. — LATERAL VIEW OF THE CONNECTION OP THE PRINCIPAL NERVES WITH THE
BRAIN.
The full description of this figure will be found at p. 553. The following references
apply to the roots of the nerves ; I, the right olfactory tract cut near its middle ; II, the
optic nerves immediately in front of the commissure ; the right optic tract is seen passing
back to the thalamus (Th\ corpora geniculata (i, e,), and corpora quadrigemina (5) ; III,
the right oculo-motor nerve ; IV, the trochlear nerve rising at v, from near the valve of
Vieussens ; V, the trifacial nerve ; VI, the abducent ocular ; a, VII, &, the facial and
auditory nerves, and between them the pars intermedia ; a, VIII, b, the roots of the
glosso-pharyngeal, pneu mo-gastric, and spinal accessory nerves ; IX, the hypoglossal
nerve ; C I, the separate anterior and posterior roots of the suboccipital or first cervical
The fibres of origin of the optic tract from the thalamus are derived partly from the
superficial stratum and partly from the interior of that body. According to Foville,
this tract is also connected with the tsenia semicircularis, and with the termination
of the gyrus fornicatus ; and he states further, that where the optic tract turns round
the back of the thalamus and the cerebral peduncle it receives other delicate fibres,
which descend from the grey matter of those parts. — (Op. cit. p. 514.)
Q Q
586 THE CRANIAL NERVES.
3. The third pair of nerves (motores oculorum) have their apparent or
superficial origin from the inner surface of the crura cerebri in the inter-
peduncular space, immediately in front of the pons. Each nerve consists
of a number of funiculi which arise in an oblique line from the surface.
The deeper fibres of origin, when followed into the cms, are found to diverge
in its substance, some being traced to the locus niger, others running down-
wards in the pons among its longitudinal fibres, and others turning upwards to be
connected with the corpora quadrigemina and Vieussenian valve. According to
Stilling, with whom Kolliker agrees, the major part of the fibres arise from a grey
nucleus in the floor of the Sylvian aqueduct, close to the origin of some fibres of the
fourth nerve.
4. The fourth pair, pathetic or trochlear nerves, the smallest of those
which are derived from the brain, are seen at the outer side of the crura
cerebri immediately before the pons. Each nerve may be traced backwards
round the peduncle to a place below the corpora quadrigemina, where it arises
from the upper part of the valve of Vieussens. Kolliker states that, under
the corpora quadrigemina, the fibres of origin are divided into two bundles ;
the anterior being traceable through the lateral wall of the aqueduct of
Sylvius to its floor, where it arises from a grey nucleus close to the middle
line ; the posterior bundle being derived from a grey nucleus in the floor of
the fourth ventricle, close to the origin of the fifth nerve. The roots of the
nerves of opposite sides are connected together across the middle line in the
form of a white band or commissure in the substance of the velum.
5. The fifth pair of nerves, par trigeminum, trifacial nerves, take their
superficial origin from the side of the pons Varolii, where the transverse
fibres of the latter are prolonged into the middle crus cerebelli, considerably
nearer to the upper than to the lower border of the pons.
The fifth nerve consists of a larger or sensory, and a smaller or motor
root. The smaller root is at first concealed by the larger, and is placed a
little higher up, there being often two or three cross fibres of the pons
between them. On separating the two roots, the lesser one is seen to
consist of a very few funiculi. In the larger root the funiculi are numerous,
amounting sometimes to nearly a hundred.
Deep origin. — The greater root runs behind the transverse fibres of the pons towards
the lateral part of the medulla oblongata at the back of the olivary body. Several
anatomists trace it into the floor of the fourth ventricle, between the fasciculi teretes
and the restiform bodies. By some it is considered to be continuous with the fasci-
culi teretes and lateral columns of the cord, whilst others connect it with the grey
mass which is regarded by Stilling as the nucleus of the glosso-pharyngeal nerve.
The motor root was supposed by Bell to descend to the pyramidal body, and
Retzius believes that he has confirmed that opinion by dissection : but it would
appear that the deep connection of this root is not yet known with certainty.
According to Stilling the fibres pass through the pons to the floor of the fourth
ventricle, and have their origin in its grey matter.
According to Foville, some of the fibres of the sensory root of the fifth nerve are
connected with transverse fibres in the pons, whilst others spread out on the surface
of the middle peduncle of the cerebellum, and enter that part of the encephalon
beneath the folia.— (Op. cit. p. 506.)
6. The sixth nerve (abducens), motor oculi externus, takes its apparent
origin from between the pyramidal body and the pons Varolii by means
of a larger and a smaller bundle. It is connected with the pyramid, and to
a small extent with the pons also. Philipeaux and Vulpian, with whom
ROOTS OF THE CRANIAL NERVES. 687
Kolliker concurs, state that the fibres may be traced more deeply to the
floor of the fourth ventricle.
7. The seventh pair of nerves appear on each side at the posterior margin
of the pons, between the middle and inferior peduncles of the cerebellum,
and nearly in a line with the place of attachment of the fifth nerve.
Deep origins. — The portio dura or facial nerve, placed a little nearer to the middle
line than the portio mollis, may be traced to the medulla oblongata between the resti-
form and olivary fasciculi, with both of which it is said to be connected. Some of its
fibres are derived from the pons. Philipeaux and Vulpian affirm that the fibres arise
from the outer wall of the fourth ventricle, and that many of them decussate in its
floor.
Connected with the portio dura, and intermediate between it and the portio
mollis, is a smaller white funiculus, first described by Wrisberg (portio inter duram et
mollein). The roots of this accessory or intermediate portion are connected deeply
with the lateral column of the cord.
The portio mollis, or auditory nerve, rises from the floor of the fourth ventricle, at
the back of the medulla oblongata, in which situation, as already described, trans-
verse white striae are seen, which form the commencement of the nerve. These
roots are connected with the grey matter, and some appear to come out of the median
fissure. The nerve then turns round the restiform body, and becomes applied to the
lower border of the pons, receiving accessions from the former of those parts, and
according to some authors from the latter also.
Eoville says that the roots of the portio mollis are also connected by a thin layer
on the under surface of the middle peduncle with the cortical substance of the cere-
bellum ; also, with the small lobule named the flocculus ; and with the grey matter at
the borders of the calamus scriptorius.
8. The eighth nerve consists of three distinct portions.
The uppermost portion is the glosso-pharyngeal nerve ; next to this, and
lower down, is the par vagum or pneumo-gastric nerve consisting of a larger
number of cords. The roots of both these nerves are attached superficially
to the fore part of the restiform. body. Still lower, is the spinal accessory
nerve, which, ascending from the side of the spinal cord, enters the skull by
the foramen magnum, and is associated with the pneumo-gastric nerve as it
passes out through the foramen lacerum.
The accessory nerve arises within the spinal canal from the lateral
column of the cord behind its middle, by a series of slender roots, which
commence as low down as the fifth or sixth cervical nerve. The nerve
passes upwards between the posterior roots of the cervical nerves and the
ligamentum deiiticulatuin, — the several funiculi of origin successively joining
it as it ascends. On entering the skull, it receives funiculi from the side
of the medulla oblongata.
These three portions of the eighth pair are connected deeply with grey nuclei
within the cord and medulla oblongata, as already described (see p. 521 ).
9. The ninth nerve (hypoglossal) arises, in a line continuous with that
of the anterior roots of the spinal nerves, by scattered funiculi from the
furrow between the olivary body and the anterior pyramid.
The roots of the ninth nerve are traced by Stilling to one of the grey nuclei already
described in the medulla oblongata, and they are said by Kolliker to undergo partial
decussation in the floor of the fourth ventricle.
DISTRIBUTION OF THE CRANIAL NERVES.
Mode of exit from the cranium. — Each of the cranial nerves issues at
first from the cranial cavity through a foramen or tubular prolongation of
the dura mater : some of these nerves or their main divisions are contained
Q Q 2
588 THE CRANIAL NERVES.
in distinct foramina of the cranium, others are grouped together in one
foramen. The numerous small olfactory nerves descend into the nose
through the cribriform plate of the ethmoid bone ; the optic nerve pierces
the root of the lesser wing of the sphenoid bone ; the third, fourth, and
sixth nerves, with the ophthalmic division of the fifth nerve, pass through the
Fig. 399.
Fig. 399. — INTERNAL VIEW OF THE B/SE OF THE SKULL, SHOWING THE PLACES OF EXIT OF
THE CKANIAL NERVES.
The dura mater is left in great part within the base of the skull ; the tentoriuin is
removed and the venous sinuses are opened. Ou the left side a small portion of the roof
of the orbit has been removed to show the relation of certain nerves at the cavernous
sinus and in the sphenoidal fissure. The roots of the several cranial nerves have been
divided at a short distance inside the foramina of the dura mater through which they
respectively pass. I, the bulb of the olfactory nerve lying over the cribriform plate of
the ethmoid bone ; II, the optic nerves, that of the left side cut short ; III, placed on the
pituitary body, indicates the common oculo-motor nerve ; IV, the trochlear nerve ; V, is
placed on the left side opposite to the middle of the three divisions of the trigeminus,
which, together with the ganglion and greater root, have been exposed by opening up
the dura mater ; on the right side the greater root is seen ; VI, placed below the foramen
of exit of the abducent ocular ; VII, placed on the upper part of the petrous bone oppo-
site the entrance of the facial and auditory nerves into the meatus auditorius internus ;
VIII, placed on the petrous bone outside the jugular foramen opposite the place of exit
of the three divisions of the eighth pair of nerves ; IX, placed upon the basilar part of
the occipital bone in front of the hypoglossal nerve as it passes through the anterior
condyloid foramen. On the left side at the cavernous sinus, the third, fourth, and
ophthalmic division of the fifth nerves are seen keeping towards the outer side, while the
sixth nerve is deeper and close to the internal carotid artery. The explanation of the
remaining references in this figure will be found at p. 461.
GENERAL DISTRIBUTION. 589
sphenoidal fissure ; the superior maxillary and inferior maxillary divisions
of the fifth pass respectively through the foramen rotundum and foramen
ovale of the great wing ; the facial and auditory nerves pierce the petrous
bone ; the three parts of the eighth pair descend in separate canals of the
dura mater through the anterior part of the jugular foramen between the
petrous and occipital bones ; and the hypoglossal nerve passes through the
anterior condyloid foramen of the occipital bone.
General distribution. — The greater number of the cranial nerves are en-
tirely confined in their distribution within the limits of the head ; as in the
case of the first six pairs and the auditory nerve. Of these, the olfactory,
optic, and auditory are restricted to their respective organs of sense ; while
the third, fourth, and sixth are exclusively motor nerves in connection with
the external and internal muscles of the eyeball and that of the upper eye-
lid. In the remaining nerve, the fifth or trifacial, all the fibres derived
from the greater root, and connected with the Gasseriau ganglion, are en-
tirely sensory in their function, and constitute the whole of the first and
second and the greater part of the third division of the nerve : but the
last of these divisions has associated with it the fibres of the lesser root,
so as to become in some degree a compound nerve. As a nerve of sensa-
tion the trifacial occupies in its distribution the greater part of the head
superficially and deeply, excepting the interior of the cranium and that
part of the scalp which is situated in the region behind a perpendicular line
passing through the external auditory meatus. The muscular distribution
of the inferior division of the fifth nerve is chiefly to the muscles of masti-
cation.
Of the remaining nerves, the facial and hypoglossal, both exclusively
motor in function, are almost entirely cephalic in their distribution ; the
facial nerve giving fibres to all the superficial and a few of the deeper
muscles of the head and face ; and the ninth or hypoglossal supplying the
muscles of the tongue. Of the facial, however, a small branch joins
one of the cervical nerves in the platysma myoides ; and of the ninth, the
descending branch supplies in part the muscles of the neck which depress
the hyoid bone and larynx.
Of the three parts of the eighth pair, ranked as cranial nerves in conse-
quence of their passing through one of the foramina of the cranium, two have
only a very limited distribution in the head, and furnish nerves in much
greater proportion to organs situated in the neck and thorax. One of these,
the pneurno-gastric, after giving a small branch to the ear-passages, and sup-
plying nerves to the larynx and pharynx, the trachea, gullet, the lungs
and heart, extends into the abdominal cavity as the principal nerve of the
stomach. The other, the spinal accessory, which is partially united with
the gloss o-pharyngeal and pneumo-gastric near their origin and thus furnishes
some of their motor fibres, is entirely a motor nerve, and is distributed in
the steruo-mastoid and trapezius muscles. The glosso-pharyngeal nerve is
more strictly confined to the head, supplying branches to the tongue,
pharynx, and part of the ear-passages.
On the following two pages, Fig. 400 is introduced in illustration of the general
view of the distribution above given. In this figure the cranium and orbit have been
opened up to the depth of the several foramina through which the nerves pass. The
greater part of the lower jaw has also been removed on the left side, and the tongue,
pharynx, and larynx are partially in view. The occipital bone has been divided by an
incision passing down from the occipital tuberosity and through the condyle to the
left of the foramen magnum. The cervical vertebrae have been divided to the left of
590 THE CRANIAL NERVES.
the middle, and the sheath of the spinal cord opened so as to expose the roots of the
cervical nerves.
Fig. 400, A.
Fig. 400.— A. SEMIDIAGRAMMATIC VIEW OF A DEEP DISSECTION OP THE CRANIAL NERVES
ON THE LEFT SIDE OF THE HEAD (from various authors and from nature). B. EXPLANA-
TORY OUTLINE OF THE SAME. ±
The roinan numerals from I to IX indicate the roots of the several cranial nerves as
they lie in or near their foramina of exit. V, is upon the great root of the fifth with the
ganglion in front ; a and b, in connection with VII, indicate respectively the facial and
auditory nerves ; a, b, and c, in connection with VIII, point respectively to the glosso-
pharyngeal, pneumo -gas trie, and spinal accessory nerves ; C I, the suboccipital or first
cervical nerve ; C VIII, the eighth. The branches or distributed parts of the nerves are
marked as follows, viz. : — I, frontal branch of the fifth ; 2, lachrymal passing into the gland;
3, nasal passing towards the internal orbitary foramen and giving the long twig to the ciliary
ganglion (4') ; 3', external branch of the internal nasal nerve ; 4, lower branch of the third
or oculo-motor nerve ; 5, the superior maxillary division of the fifth passing into the infra-
orbital canal ; 5', its issue at the infraorbital foramen and distribution as inferior
palpebral, lateral nasal, and superior labial nerves (5") ; 6, ganglion of Meckel and
Vidian nerve passing back from it ; 6', palatine and other nerves descending from it ; 6",
superior petrosal nerve ; 7, posterior superior dental nerves ; 7', placed in the antrum
maxillare, which has been opened, points to the anterior superior dental nerves ; 8,
inferior maxillary division of the fifth immediately below the foramen ovale ; 8', some of
the muscular branches coming from it ; 8 x , the anterior auricular branch cut short, and
above it the small pstrosal nerve to join the facial nerve ; 9, buccal and internal ptery-
GENERAL DISTRIBUTION.
591
gold ; 10, gustatory nerve ; 10', its distribution to the. side and front of the tongue and
to the sublingual glands ; 10", the submaxillavy ganglion connected with the gustatory
Fig. 400, B.
nerve ; below 10, the chorda tympani passing back from the gustatory to join the facial
nerve above 12 ; 11, inferior dental nerve ; 11', the same nerve and part of its dental distri-
bution exposed by removal of the jaw ; 11", termination of the same as mental and inferior
labial nerves ; 12, the twigs of the facial nerve to the posterior belly of the digastric and
to the stylo-byoid muscle immediately after its exit from the stylo-mastoid foramen ; 12',
the temporo-facial division of the facial; 12'', the cervico-facial division; 13, the trunk
of the glosso-pharyngeal passing round the stylo- pharyngeus muscle after giving pharyngeal
and muscular branches; 13', its distribution on the side and back part of the tongue ;
14, the spinal accessory nerve, at the place where it crosses the ninth and gives a com-
municating branch to the pneumo-gastric and glosso-pharyngeal nerves ; 14', the same
nerve after having passed through the sterno-mastoid muscle uniting with branches
from the cervical nerves; 15, ninth nerve; 15', its twig to the thyro-hyoid muscle;
15", its distribution in the muscles of the tongue; 16, descendens noni nerve giving
a direct branch to the upper belly of the omo-hyoid muscle, and receiving the com-
municating branches 16 x from the cervical nerve; 17, pneumo-gastric nerve; 17', its
superior laryngeal branch; 17", external laryngeal twig ; 18, superior cervical ganglion
of the sympathetic nerve, uniting with the upper cervical nerves, and giving at 18'
the superficial cardiac nerve ; 19, the trunk of the sympathetic ; 19', the middle cervical
ganglion, uniting with some of the cervical nerves, and giving 19", the large middle
cardiac nerve ; 20, continuation of the sympathetic nerve down the neck ; 21, great
occipital nerve ; 22, third occipital.
THE CRANIAL XEHVES.
OLFACTORY NERVE.
The olfactory or first cranial nerve, the special nerve of the sense of smell,
is distributed exclusively to the nasal fossae.
From the under surface of the olfactory bulb about twenty branches
proceed through the holes in the cribriform plate of the ethmoid bone, each
invested by tubular prolongations of the membranes of the brain. These
tubes of membrane vary in the extent to which they are continued on the
branches : the offsets of the dura mater sheathe the filaments, and join the
periosteum lining the nose ; those of the pia mater become blended with
the neurilemma of the nerves ; and those of the arachnoid re-ascend to the
serous lining of the skull.
Fig. 401.
XII
Fig. 401. — DISTRIBUTION OP THE OLFACTORY NKRVES ON THE SEPTUM OF THE NOSE (from
Sappey after Hirschfeld and Leveille). §
The septum is exposed and the anterior palatine canal opened on the right side. I,
placed above, points to the olfactory bulb, and the remaining roman numbers to the roots
of the several cranial nerves ; 1, the small olfactory nerves as they pass through the
cribriform plate ; 2, internal or septal twig of the nasal branch of the ophthalmic nerve ;
3, naso-palatine nerves. (See Fig. 408 for a view of the distribution of the olfactory
nerves on the outer wall of the nasal fossa.)
The branches are arranged in three sets. Those of the inner set, lodged for
some distance in grooves on the surface of the bone, ramify in the pituitary
membrane of the septum ; the outer set extend to the upper two spongy bones
and the plane surface of the ethmoid bone in front of these ; and the middle
set, which are very short, are confined to the roof of the nose. The distri-
bution of the olfactory > nerve is confined to the upper part of the nasal
fossa ; none of the branches reach the lower spongy bone. — (See Anatomy
of the Nose.)
OPTIC NERVE.
The optic or second cranial nerve, the nerve of vision, extending from
the optic commissure, becomes more cylindrical and firm as it diverges from
its fellow and enters the orbit by the optic foramen. Within the orbit it
forms a cylindrical trunk, thick and strong, with a uniform surface. On dis-
OPTIC NERVE.— THIRD PAIR.
•593
section it is seen to consist of a number of separate bundles of nerve fibres,
imbedded in tough fibrous tissue prolonged from the dura mater, and per-
forated in the centre by the small arteria centralis retinae, which passes into
it soon after it enters the orbit. It is surrounded by the recti muscles,
and, entering the eyeball posteriorly a little to the inside of its middle, it
pierces the sclerotic and choroid coats, and expands in the retina. — (See the
Anatomy of the Eye.)
It may be mentioned that in many fishes the optic nerves do not unite in a com-
missure, but merely cross each to the side opposite to that of its origin ; and that
in a number of the same animals, as was first pointed out by Malphighi, the nerve
consists of a lamina thrown into complicated longitudinal plications, and surrounded
by a sheath.
THIRD PAIR OF NERVES.
This nerve, the common motor nerve of the eyeball (motorius oculi),
gives branches to five of the seven muscles of the orbit, — viz., to the
Fig. 402. — VIEW FROM ABOVE Fig. 402.
OF THE UPPERMOST NERVES
OF THE ORBIT, THE GAS-
SERIAN GANGLION, &c. (from
Sappey after Hirschfeld and
Leveille). |
I, the olfactory tract passing
forwards into the bulb ; II, the
commissure of the optic nerves ;
IN, the oculo-motor ; IV, the
trochlear nerve; V, the greater
root of the fifth nerve, a small
portion of the lesser root is
seen below it ; VI, the sixth
nerve ; VII, facial ; VIII, audi-
tory ; IX, glosso-pharyngeal ;
X, pneumo-gastric ; XI, spinal
accessory ; XII, hypoglossal ;
1, the Gasserian ganglion; 2,
ophthalmic nerve ; 3, lachrymal
branch ; 4, frontal ; 5, external
frontal or supraorbital ; 6,
internal frontal ; 7, supra-
trochlear branch ; 8, nasal
nerve ; 9, infratrochlear branch ;
] 0, internal nasal passing
through the internal orbital
foramen; 11, anterior deep
temporal proceeding from the
buccal nerve ; 12, middle deep
temporal ; 13, posterior deep
temporal arising from the
masseteric ; 14, origin of the
temporo-auricular ; 15, great superficial petrosal nerve.
superior, internal and inferior straight muscles, to the levator palpebrse, and
to the inferior oblique muscle.
Cylindrical and firm, like the other motor nerves, the third nerve,
quitting the investment of the arachnoid membrane, pierces the inner layer
of the dura mater close to the posterior clinoid process, and proceeds
towards the sphenoidal fissure, lying in the external fibrous boundary of the
cavernous sinus.
594 THE CRANIAL NERVES.
After receiving one or two delicate filaments from the cavernous plexus of
the sympathetic, the third nerve divides near the orbit into two parts, which
are continued into that cavity between the heads of the external rectus
muscle, and separated one from the other by the nasal branch of the
ophthalmic nerve.
The upper, the smaller part, is directed inwards over the optic nerve to
the superior rectus muscle of the eye and the elevator of the eyelid, to both
which muscles it furnishes branches.
The lower and larger portion of the nerve separates into three branches ;
of these one reaches the inner rectus ; another the lower rectus ; and the
third, the longest of the three, runs onwards between the lower and the
outer rectus, and terminates below the ball of the eye in the inferior
oblique muscle. The last-mentioned branch is connected with the lower
part of the lenticular ganglion by a short thick cord, and gives two filaments
to the lower rectus muscle.
The several branches of the third nerve enter the muscles to which they
are distributed on the surface which in each looks towards the eyeball
POSITION OP CERTAIN NERVES at the cavernous sinus, and as they enter the
orbit. — There are several nerves, besides the third, placed close together at
the cavernous sinus, and entering the orbit through the sphenoidal fissure.
To avoid repetition hereafter, the relative positions of these nerves may
now be described. The nerves thus associated are the third, the fourth,
the ophthalmic division of the fifth, and the sixth.
At the cavernous sinus. — In the dura mater which bounds the cavernous
sinus on the outer side, the third and fourth nerves and the ophthalmic
division of the fifth are placed, as regards one another, in their numerical
order both from above downwards and from within outwards. The sixth
nerve is placed separately from the others close to the carotid artery,
on the floor of the sinus and internally to the fifth nerve. Near the sphe-
noidal fissure, through which they enter the orbit, the relative position of
the nerves is changed, the sixth nerve being here close to the rest, and
their number is augmented by the division of the third and the ophthalmic
nerves — the former into two, the latter into three parts.
In the sphenoidal fissure. — The fourth and the frontal and lachrymal
branches of the fifth, which are here higher than the rest, lie on the same
level, the fourth being the nearest to the inner side, and enter the orbit
above the muscles. The remaining nerves pass between the heads of the
outer rectus muscle, in the following relative position to each other ; the
upper division of the third highest, the nasal branch of the fifth next, the
lower division of the third beneath these, and the sixth lowest of all.
FOURTH PAIR OF NERVES.
The fourth (nervus trochlearis, n. patheticus) is the smallest of the cranial
nerves, and is distributed entirely to the upper oblique muscle of the
orbit.
From the remoteness of its place of origin, the part of this nerve within
the skull is longer than that of any other cranial nerve. It enters an aperture
in the free border of the tentorium, outside that for the third nerve, and
near the posterior clinoid process. Continuing onwards through the outer
wall of the cavernous sinus, the fourth nerve enters the orbit by the
sphenoidal fissure, and above the muscles. Its position with reference to
other nerves in this part of its course has been already described.
FOURTH PAIE.
595
In the orbit, the fourth nerve inclines inwards above the muscles, and
enters finally the upper oblique muscle at its orbital surface.
While in its fibrous canal in the outer wall of the sinus, the fourth nerve is joined
by filaments of the sympathetic, and not unfrequently is blended with the ophthalmic
Fig. 403. — VIEW FROM ABOVE OP THE MOTOR NERVES
OF THE EYEBALL AND ITS MUSCLES (after Hirsch-
feld and Leveille, altered).
Fig. 403.
The ophthalmic division of the fifth pair has been
cut short ; the attachment of the muscles round the
optic nerve has been opened up, and the three upper
muscles turned towards the inner side, their anterior
parts being removed ; a part of the optic nerve is cut
away to show the inferior rectus ; and a part of the
sclerotic coat and cornea is dissected off showing the
iris, zona ciliaris, and choroid coat, with the ciliary
nerves.
«, the upper part of the internal carotid artery
emerging from the cavernous sinus ; 6, the superior
oblique muscle ; &', its anterior part passing through
the pulley ; c, the levator palpebrse superioris ; d,
the superior rectus ; e, the internal rectus ; /, the
external rectus; /', its upper tendon turned down ;
gr, the inferior rectus j h, insertion of the inferior
oblique muscle.
II, the commissure of the optic nerve ; II', part
of the optic nerve entering the eyeball ; III, the
common oculo-motor ; IV, the fourth or trochlear
nerve ; V, the greater root of the trigeminus ; V,
the smaller or motor root ; VI, the abducent nerve ;
1, the upper division of the third nerve separating
from the lower and giving twigs to the levator palpe-
brse and superior rectus ; 2, the branches of the
lower division supplying the internal and inferior
recti muscles ; 3, the long branch of the same nerve
proceeding forward to the inferior oblique muscle,
and close to the number 3, the short thick branch
to the ciliary ganglion : this ganglion is also shown,
receiving from behind the slender twig from the nasal nerve, which has been cut short,
and giving forwards some of its ciliary nerves, which pierce the sclerotic coat ; 3', marks
the termination of some of these nerves in the ciliary muscle and iris after having passed
between the sclerotic and choroid coats ; 4, the distribution of the trochlear nerve to the
upper surface of the superior oblique muscle ; 6, the abducent nerve passing into the
external rectus.
division of the fifth. Bidder states that three or more small filaments of this nerve
extend in the tentorium as far as the lateral sinus ; and has figured one as joining the
sympathetic on the carotid artery. (Neurologische Beobachtungen, Von F. H. Bidder.
Dorpat, 1836.)
FIFTH PAIR OF NERVES.
The fifth, or trifacial nerve (nerv. trigeminus), the largest cranial nerve,
is analogous to the spinal nerves, in respect that it consists of a motor and
a sensory part, and that the sensory fibres pass through a ganglion while
the motor do not. Its sensory division, which is much the larger, imparts
common sensibility to the face and the fore part of the head, as well as to
the eye, the nose, the ear, and the mouth ; and endows the fore part of
the tongue with the powers of both touch and taste. The motor root
supplies chiefly the muscles of mastication.
596
THE CRANIAL NERVES.
The roots of the fifth nerve, after emerging from the surface of the
encephalon, are directed forwards, side by side, to the middle fossa of the
skull, through a recess in the dura mater on the summit of the petrous
part of the temporal bone. Here the larger root alters in appearance : its
Fig- 404. Fig. 404.— GENERAL PLAN
OP THE BRANCHES OF
THE FIFTH PAIR (after
a sketch by Charles
Bell), i
1, lesser root of the
fifth pair ; 2, greater
root passing forwards
into the Gasserian gang-
lion ; 3, placed on the
bone above the ophthal-
mic nerve, which is seen
dividing into the supra-
orbital, lachrymal, and
nasal branches, the latter
connected with the oph-
thalmic ganglion ; 4,
placed on the bone close
to the foramen rotundum,
marks the superior max-
illary division, which is
connected below with the
spheno-palatine ganglion,
and passes forwards to
the infraorbital foramen ;
5, placed on the bone over
the foramen ovale, marks
the submaxillary nerve,
giving off the anterior auri-
cular and muscular bran-
ches, and continued by the
inferior dental to the lower
jaw, and by the gustatory
to the tongue ; a, the submaxillary gland, the submaxillary ganglion placed above it in
connection with the gustatory nerve ; 6, the chorda tympaui ; 7, the facial nerve issuing
from the stylo-rnastoid foramen.
fibres diverge a little, become reticulated, and enter the Gasserian ganglion.
The smaller root passes inside and beneath the ganglion, without its nerve-
fibres being incorporated in any way with it, and joins outside the skull the
lowest of the three trunks which issue from the ganglion.
The ganglion of the fifth nerve or Gasserian ganglion (ganglion semilunare),
occupies a depression on the upper part of the petrous portion of the
temporal bone, near the point, and is somewhat crescentic in form, the
convexity being turned forwards. On its inner side the ganglion is joined
by filaments from the carotid plexus of the sympathetic nerve, and, accord-
ing to some anatomists, it furnishes from its back part filaments to the
dura mater.
From the fore part, or convex border of the Gasserian ganglion, proceed
the three large divisions of the nerve. The highest (first or ophthalmic trunk)
enters the orbit ; the second, the upper maxillary nerve, is continued forwards
to the face, below the orbit ; and the third, the lower maxillary nerve, is
distributed chiefly to the external ear, the tongue, the lower teeth, and the
muscles of mastication. The first two trunks proceed exclusively from the
FIFTH PAIR.-OPHTHALMIC NERVE. 597
ganglion and are entirely sensory, while the third or inferior maxillary trunk,
receiving a considerable part from the ganglion, has associated with it also
the whole of the fibres of the motor root, and thus distributes both motor
and sensory branches.
OPHTHALMIC NERVE.
The ophthalmic nerve, or first division of the fifth nerve, the smallest of
the three offsets from the Gasserian ganglion, is somewhat flattened, about an
inch in length, and is directed forwards and upwards to the spheuoidal
fissure, where it ends in branches which pass through the orbit to the sur-
face of the head and to the nasal fossse. In the skull it is contained in the
process of the dura mater bounding externally the cavernous sinus, and is
joined by filaments from the cavernous plexus of the sympathetic : according
to Arnold, it gives recurrent branches to the tentorium cerebelli. It also
frequently communicates by a considerable branch with the fourth nerve.
Near the orbit the ophthalmic nerve furnishes from its inner side the
nasal branch, and then divides into the frontal and lachrymal branches.
These branches are transmitted separately through the sphenoidal fissure, and
are continued through the orbit (after supplying some filaments to the eye
and the lachrymal gland) to their final distribution in the nose, the eyelids,
and the muscles and integument of the forehead.
LACHRYMAL BRANCH.
The lachrymal branch is external to the frontal at its origin, and is con-
tained in a separate tube of dura mater. In the orbit it passes along the
outer part, above the muscles, to the outer and upper angle of the cavity.
Near the lachrymal gland, the nerve has a connecting filament with the orbital
branch of the superior maxillary nerve ; and when in close apposition with the
gland, it gives many filaments to that body and to the conjunctiva. Finally,
the lachrymal nerve penetrates the palpebral ligament externally, and ends
in the upper eyelid, the terminal ramifications being joined by twigs from
the facial nerve.
In consequence of the junction which occurs between the ophthalmic trunk of the
fifth and the fourth nerve, the lachrymal branch sometimes appears to be derived
from both these nerves. Swan considers this the usual condition of the lachrymal
nerve. (" A Demonstration of the Nerves of the Human Body," page 36. London,
1834.)
FRONTAL BRANCH.
The frontal branch, the largest division of the ophthalmic, lies, like the
preceding nerve, above the muscles in the orbit, being situated between the
elevator of the upper eyelid and the periosteum. About midway forwards
in the orbit, the nerve divides into two branches, supratrochlear and supra-
orbital.
a. The supratrochlear branch (internal frontal) is prolonged to the inner
angle of the orbit, close to the point at which the pulley of the upper oblique
muscle is fixed to the orbit. Here it gives downwards a filament to connect
it with the infratrochlear branch of the nasal nerve, and issues from the
cavity between the orbicular muscle of the lids and the bone. In this position
filaments are distributed to the upper eyelid. The nerve next pierces the
598 THE CRANIAL NERVES.
orbicularis palpebrarum and occipito-frontalis muscles, furnishing twigs to
these muscles and the corrugator supercilii, and, after ascending on the fore-
head, ramifies in the integument.
6. The supraorbital branch (external frontal) passes through the supra-
orbital notch to the forehead, and ends in muscular, cutaneous, and peri-
cranial branches ; while in the notch it distributes palpebral filaments to the
upper eyelid.
The muscular branches referred to are comparatively small, and supply the corrugator
of the eyebrow, the occipito-frontalis, and the orbicular muscle of the eyelids, joining
the facial nerve in the last muscle. The cutaneous branches, among which two (outer
and inner) may be noticed as the principal, are placed at first beneath the occipito-
frontalis. The outer one, the larger, perforates the tendinous expansion of the muscle,
and ramifies in the scalp as far back as the lambdoidal suture. The inner branch
reaches the surface sooner than the preceding nerve, and ends in the integument over
the parietal bone. The pericranial branches arise from the cutaneous nerve beneath
the muscle, and end in the pericranium covering the frontal and parietal bones.
Fig. 405. Fig. 405.— NERVES OP THE OR-
BIT FKOM THE OUTER SlDE
t "&- "$?ifrli (from Sappey after Hirschfeld
and Leveilld). f
The external rectus muscle has
been divided and turned down: 1,
the optic nerve; 2, thetrunkof the
third nerve; 3, its upper divisioa
pasing into the levator palpebrae
and superior rectus ; 4, its long
lower branch to the inferior oblique
muscle ; 5, the sixth or abducent
nerve joined by twigs from the
sympathetic ; 6, the Gasserian
8 7 10 " -A ganglion ; 7, ophthalmic nerve ; 8,
its nasal branch ; 9, the ophthal-
mic ganglion ; 10, its short or
motor root ; 11, long sensory root from the nasal nerve; 12, sympathetic twig from
the carotid plexus ; 13, ciliary nerves passing into the eyeball ; 14, frontal branch of the
ophthalmic nerve.
NASAL BRANCH.
The nasal branch (oculo-nasalis), separating from its parent trunk in the
wall of the cavernous sinus, enters the orbit between the heads of the outer
rectus. It then inclines inwards over the optic nerve, beneath the elevator
of the upper eyelid and the superior rectus muscle, to the inner wall of the
orbit, through which it passes by the anterior internal orbital foramen. In
this oblique course across the orbit it furnishes a single filament to the
ophthalmic ganglion, two or three (long ciliary) directly to the eyeball ; and,
at the inner side of the cavity, a considerable branch (infratrochlear), which
issues from the orbit at the fore part.
On leaving the orbit the nasal nerve is directed transversely inwards to
the upper surface of the cribriform plate of the ethmoid bone, and, passing
forwards in a groove at its outer edge, within the cranium, descends by a
special aperture close to the crista galli at the fore part of the plate to the
roof of the nasal fossa, where it divides into two branches, one of which
(external or superficial nasal) reaches the integument of the side of the nose,
and the other (rainus septi) ramifies in the pituitary membrane.
NASAL NERVE.— OPHTHALMIC GANGLION. 599
a. The branch to the ophthalmic ganglion (radix longa ganglii ciliaris), very slender,
and about half an inch long, arises generally between the heads of the external
rectus ; it lies on the outer side of the optic nerve, and enters the upper and back
part of the ophthalmic ganglion, constituting its long root.
This small branch is sometimes joined by a filament from the cavernous plexus of
the sympathetic, or from the upper branch of the third nerve.
b. The long ciliary nerves, two or three in number, are situated on the inner side
of the optic nerve ; they join one or more of the nerves from the ophthalmic ganglion
(short ciliary), and after perforating the sclerotic coat of the eye, are continued
between it and the choroid to the ciliary muscle, the cornea, and the iris.
c. The infratrochlear branch runs forwards along the inner side of the orbit below
the superior oblique muscle, and receives near the pulley of that muscle a filament of
connection from the supratrochlear nerve. The branch is then continued below the
pulley to the inner angle of the eye, and ends in filaments which supply the orbicular
muscle of the lids, the caruncula, and the lachrymal sac, as well as the integument of
the eyelids and side of the nose.
In the cavity of the nose the nasal nerve ends by dividing into the following
branches.
d. The branch to the nasal septum extends to the lower part of the partition
between the nasal fossae, supplying the pituitary membrane near the fore part of the
septum.
e. The superficial branch (externus seu lateralis), descends in a groove on the inner
surface of the nasal bone ; and after leaving the nasal cavity between that bone and
the lateral cartilage of the nose, it is directed downwards to the tip of the nose,
beneath the compressor naris muscle. While within the nasal fossa, this branch
gives two or three filaments to the fore part of its outer wall, which extend as far as
the lower spongy bone. The cutaneous part is joined by a filament of the facial
nerve.
Summary. — The first division of the fifth nerve is altogether sensory in
function. It furnishes branches to the ball of the eye and the lachrymal
gland ; to the mucous membrane of the nose and eyelids ; to the integument
of the nose, the upper eyelid, the forehead, and the upper part of the hairy
scalp ; and to the muscles a'bove the middle of the circumference of the
orbit. Some of the cutaneous and muscular filaments join branches of the
facial nerve, and the nerve itself communicates with the sympathetic.
OPHTHALMIC GANGLION.
There are four small ganglia connected with the divisions of the fifth
nerve : the ophthalmic ganglion with the first, Meckel's ganglion with the
second, and the otic and submaxillary ganglia with the third. These
ganglia, besides receiving branches from the sensory part of the fifth, are
each connected with a motor nerve from the third, the fifth, or the facial,
and with twigs from the sympathetic ; and the nerves thus joining the
ganglia are named their roots.
The ophthalmic or lenticular ganglion (gang, semilunare, vel ciliare) serves
as a centre for the supply of nerves — motor, sensory, and sympathetic — to
the eyeball. It is a small reddish body, situated at the back of the orbit,
between the outer rectus muscle and the optic nerve, and generally in contact
with the ophthalmic artery ; it is joined behind by branches from the fifth,
the third, and the sympathetic nerves ; while from its fore part proceed the
ciliary nerves to the eyeball.
Union of the ganglion with nerves : its roots. — The posterior border of the
ganglion receives three nerves. One of these, the long root, a slender
filament from the nasal branch of the ophthalmic trunk, joins the upper
part of this border. Another branch, the short rooty much thicker and
shorter than the preceding, and sometimes divided into parts, is derived
600 THE CRANIAL NERVES.
from the branch of the third nerve to the inferior oblique muscle, and is
connected with the lower part of the ganglion. The third root is a very
small nerve which emanates from the cavernous plexus of the sympathetic,
and reaches the ganglion with the long upper root : these two nerves are
sometimes conjoined before reaching the ganglion. Other roots have been
assigned to the ganglion. (Valentin, in Miiller's Archiv. for 1840.)
Brandies of the ganglion. — From the fore part of the ganglion arise ten
or twelve delicate filaments — the short ciliary nerves. These nerves are
disposed in two fasciculi, arising from the upper and lower angles of the
ganglion, and they run forwards, one set above, the other below the optic
nerve, the latter being the more numerous. They are accompanied by fila-
ments from the nasal nerve (long ciliary), with which some are joined. Having
entered the eyeball by apertures in the back part of the sclerotic coat, the
nerves are lodged in grooves on its inner surface ; and at the ciliary muscle,
which they pierce (some filaments supplying it and the cornea), they turn
inwards and ramify in the iris.
SUPERIOR MAXILLARY NERVE.
The superior maxillary nerve, or second division of the fifth cranial nerve,
is intermediate in size between the ophthalmic and the inferior maxillary
trunks.
It commences at the middle of the Gasserian ganglion, and, passing hori-
zontally forwards, soon leaves the skull by the foramen rotuudum of the
sphenoid bone. The nerve then crosses the spheno-maxillary fossa, and
enters the infraorbital canal of the upper maxilla, by which it is conducted
to the face. After emerging from the infraorbital foramen, it terminates
beneath the elevator of the upper lip in branches which spread out to the
side of the nose, the eyelid, and the upper lip.
Branches. — In the spheno-maxillary fossa a temporo-malar branch
ascends from the superior maxillary nerve to the orbit, and two spheno-
palatine branches descend to join Meckel's ganglion. Whilst the nerve is
in contact with the upper maxilla, it furnishes two posterior dental branches
on the tuberosity of the bone, and an anterior dental branch at the fore part.
On the ace are the terminal branches already indicated.
ORBITAL BRANCH.
The orbital or temporo-malar branch, a small cutaneous nerve, enters the
orbit by the spheno-maxillary fissure, and divides into two branches
(temporal and malar), which pierce the malar bone, and are distributed to
the temple and the prominent part of the cheek.
a. The temporal branch is contained in an osseous groove or canal in the
outer wall of the orbit, and leaves this cavity by a foramen in the malar
bone. When about to traverse the bone, it is joined by a communicating
filament (in some cases, two filaments) from the lachrymal nerve. The
nerve is then inclined upwards in the temporal fossa between the bone and
the temporal muscle, perforates the aponeurosis over the muscle an inch
above the zygoma, and ends in cutaneous filaments over the temple. The
cutaneous ramifications are united with the facial nerve, and sometimes
with the superficial temporal nerve of the third division of the fifth.
6. The malar branch lies at first in the loose fat in the lower angle of the
orbit, and is continued to the face through a foramen in the fore part of
SUPERIOR MAXILLARY NERVE. 601
the malar bone, where it is frequently divided into two filaments. In the
prominent part of the cheek this nerve communicates with the facial nerve.
Fig. 406.
Fig. 406. — SUPERIOR MAXILLARY NERVE AND SOME OF THE ORBITAL NERVES (from
Sappey after Hirschfeld and Leveille). 3
1, the Gasserian ganglion ; 2, lachrymal branch of the ophthalmic nerve; 3, trunk of the
superior maxillary nerve ; 4, its orbital branch, joining at 5, the palpebral twig of the
lachrymal ; 6, origin of its malar twig ; 7, its temporal twig ; 8, spheno-palatine ganglion ;
9, Vidian nerve ; 10, its upper branch or great superficial petrosal nerve proceeding to join
the facial nerve (11) ; 12, union of the lower branch of the Vidian nerve with the carotid
branch of the sympathetic ; 13, 14, posterior dental nerves ; 15, terminal branches of the
infrnorbital nerves ramifying on the side of the nose and upper lip ; 16, a branch of the
facial uniting with some of the twigs of the infraorbital.
POSTERIOR DENTAL BRANCHES.
The posterior dental branches, two in number, are directed downwards
and outwards over the back part and tuberosity of the maxillary bone.
One of the branches enters a canal in the bone by which it is conducted
to the teeth, and gives forwards a communicating filament to the anterior
dental nerve. It ends in filaments to the molar teeth and the lining mem-
brane of the maxillary sinus, and near the teeth joins a second time with
the anterior dental nerve.
The anterior of the two branches, lying on the surface of the bone, is
distributed to the gums of the upper jaw and to the buccinator muscle.
ANTERIOR DENTAL BRANCH.
The anterior dental branch, leaving the trunk of the nerve at a varying
distance behind its exit from the infraorbital foramen, enters a special canal
in front of the antrum of Highmore. In this canal it receives the com-
municating filament from the posterior dental nerve, and divides into two
branches, which furnish offsets for the front teeth.
(a) The inner branch supplies the incisor and canine teeth. Filaments from this
nerve enter the lower meatus of the nose, and end in the membrane covering the
lower spongy bone. Also above the root of the canine tooth, it unites with a branch of
the posterior nasal nerve from Meckel's ganglion, and forms with it a small thickening,
602 THE CRAXIAL NERVES.
the ganglion of Bochdalcl, from which branches are described as descending to the
alveolar process and gums of the incisor and canine teeth. (See Hyrtl's Lehrbuch,
p. 804.)
(b) The outer branch gives filaments to the bicuspid teeth, and is connected with
the posterior dental nerve.
TNFRAORBTTAL BRANCHES.
The infraorbital branches, large and numerous, spring from the end of
the superior maxillary nerve beneath the elevator muscle of the upper lip,
and are divisible into palpebral, nasal, and labial sets.
Fig. 407.
Fig. 407. — DEEP VIEW OP THE SpnENo-PALATiNE GANGLION, AND ITS CONNECTIONS WITH
OTHEK NEKVES, &c. (from Sappey after Hirschfeld and Leveille). f
1, superior maxillary nerve ; 2, posterior superior dental ; 3, second posterior dental
branch ; 4, anterior dental ; 5, union of these nerves ; 6, spheno-palatine ganglion ; 7,
Vidian nerve ; 8, its great superficial petrosal t ranch ; 9, its carotid branch ; 10, a part
of the sixth nerve, receiving twigs from the carotid plexus of the sympathetic ; 11, superior
cervical sympathetic ganglion ; 12, its carotid branch ; 13, trunk of the facial nerve near
the knee or bend at the hiatus Fallopii : 14, glosso-pharyngeal nerve ; 15, anastomosing
branch of Jacobson ; 16, twig uniting it to the sympathetic : 17, filament to the fenestra
rotunda ; 18, filament to the Eustachian tube ; 19, filament to the fenestra ovalis ; 20,
external deep petrosal nerve uniting with the lesser superficial petrosal ; 21, internal deep
petrosal twig uniting with the great superficial petrosal.
a. The palpebral branch (there are sometimes two branches) turns upwards to the
lower eyelid in a groove or canal of the bone, and supplies the orbicular muscle ; it
ends in filaments which are distributed to the eyelid in its entire breadth. At the
outer angle of the eyelids this nerve is connected with the facial nerve.
b. The nasal branches, directed inwards to the muscles and integument of the side
of the nose, communicate with the cutaneous branch of the nasal nerve.
c. The labial, the largest of the terminal branches of the upper maxillary nerve,
and three or four in number, are continued downwards beneath the proper elevator
of the upper lip. Eamifying as they descend, these nerves are distributed to the
integument, the mucous membrane of the mouth, the labial glands, and the muscles
of the upper lip.
Near the orbit the infraorbital branches of the superior maxill try nerve
are joined by considerable branches of the facial nerve, the union between
the two being named infraorbital plexus.
SPHENO-PALAT1NE GANGLION. 603
SPHENO-PALATINE GANGLION".
The splieno-palatine ganglion, frequently named Meckel's ganglion, is
deeply placed in the spheno-maxillary fossa, close to the spheno-palatine
foramen. It receives the two spheno-palatine branches, which descend
together from the superior maxillary nerve as it crosses the top of the fossa.
It is of a greyish colour, triangular in form, and convex on the outer
surface. The grey or ganglionic substance does not involve all the fibres
of the spheno-palatiue branches of the upper maxillary nerve, but is placed
at the back part, at the point of junction of the sympathetic or deep
branch of the Vidian, so that the spheuo-palatine nerves proceeding to the
nose snd palate pass to their destination without being incorporated with
the gangliouic mass.
Branches proceed from the ganglion upwards to the orbit, downwards to
the palate, inwards to the nose, and backwards through the Vidian and
pterygo-palatine canals.
ASCENDING BRANCHES. — There are three or more very small twigs,
which reach the orbit by the spheno-maxillary fissure, and are distributed to
the periosteum.
Bock describes a branch ascending from the ganglion to the sixth nerve; Tiede-
mann, one to the lower angle of the ophthalmic ganglion. The filaments described
by Hirzel as ascending to the optic nerve, most probably join the ciliary twigs which
surround that nerve.
DESCENDING BRANCHES. — These are three in number, — the large, the
small, and the external palatine nerves, and are continued chiefly from
the spheno-palatine branches of the superior maxillary. They are distri-
buted to the tonsil, the hard and soft palate, the gums, and the mucous
membrane of the nose.
a. The larger or anterior palatine nerve descends in the palato-maxillary canal,
and divides in the roof of the mouth into branches, which are received into grooves
in the hard palate, and extend forwards nearly to the incisor teeth. In the mouth it,
supplies the gums, the glandular structure and the mucous membrane of the hard
palate, and joins in front with the naso-palatine nerve. When entering its canal,
this palatine nerve gives a nasal branch which ramifies on the middle and lower
spongy bones ; and a little before leaving the canal, another branch is supplied to
the membrane covering the lower spongy bone : these are inferior nasal branches.
Opposite the lower spongy bone springs a small branch, which is continued to the
soft palate in a separate canal behind the trunk of the nerve.
1). The smaller or posterior palatine branch, arising near the preceding nerve,
enters with a small artery the lesser palatine canal, and is conducted to the soft
palate, the tonsil, and the uvula. According to Meckel, it supplies the levator
palati muscle.
c. The external palatine nerve, the smallest of the series, courses between the
upper maxilla and the external pterygoid muscle, and enters the external palatine
canal between the maxillary bone and the pterygoid process of the palate bone. At
its exit from the canal it gives inwards a branch to the uvula, and outwards another
to the tonsil and palate. Occasionally, this nerve is altogether wanting.
INTERNAL BRANCHES. — These consist of the naso-palatine, and the upper
and anterior nasal, which ramify iii the lining membrane of the nasal fossae
and adjoining sinuses.
The upper nasal are very small branches, and enter the back part of the nasal
fossa by the spheno-palatine foramen. Some are prolonged to the upper and
posterior part of the septum, and the remainder ramify in the membrane covering
it R 2
604
THE CRANIAL NERVES.
the upper two spongy bones, and in that lining the posterior ethmoid cells. A
branch, as has been already stated, forms a connection in the wall of the maxillary
sinus, above the eye-tooth, with the anterior dental nerve.
The naso-palatine nerve, nerve of Cotunnius (Scarpa), long and slender, leaves the
inner side of the ganglion with the preceding branches, and after crossing the roof of
the nasal fossa is directed downwards and forwards on the septum nasi, towards the
anterior palatine canal, situated between the periosteum and the pituitary membrane.
The nerves of opposite sides descend to the palate through the mesial subdivisions of
the canal, called the foramina of Scarpa, the nerve of the right side usually behind
that of the left. In the lower common foramen the two naso-palatine nerves are
connected with each other ; and they end in several filaments, which are distributed
to the papilla behind the incisor teeth, and communicate with the great palatine
nerve. In its course along the septum, small filaments are furnished from the naso-
palatine nerve to the pituitary membrane. (See Fig 402. This nerve was discovered
independently by John Hunter and Cotunnius ; see Hunter's " Observations on
certain parts of the Animal Economy;" and Scarpa, "Annotationes Anatomicse,"
lib. ii.)
Fig. 408.
Fig. 408. — NEIIVKS OP THE NOSE AND OF THE SPHENO-PALATINE GANGLION FROM THR
INNER SIDE (from Sappey after Hirschftld and Leveille). f
1, network of the branches of the olfactory nerve descending upon the membrane
covering the superior and middle turbinated bones ; 2, external twig of the ethinoidal branch
of the nasal nerve ; 3, spheno-palatine ganglion ; 4, ramification of the anterior division
of the palatine nerves ; 5, posterior, and 6, middle divisions of the palatine nerves; 7,
branch to the membrane on the lower turbinated bone ; 8, branch to the superior and
middle turbinated bones ; 9, naso-palatine branch to the septum cut short ; 10, Vidian
nerve ; 11, its great superficial petrosal branch; 12, its carotid branch; 13, the sympa-
thetic nerves ascending on the internal carotid artery.
POSTERIOR BRANCHES. — The brandies directed backwards from the splieno-
palatine ganglion are the Vidian aud pharyngeal nerves.
The Vidian nerve arises from the back part of the ganglion, which seems to be pro-
longed into it, passes backwards through the Vidian canal, and after emerging from
this divides in the substance of the fibro-cartilage filling the foramen lacerum
medium, into two branches : one of these, the superficial petrosal, joins the facial
nerve, while the other, the carotid branch, communicates with the sympathetic.
Whilst the Vidian nerve is in its canal, it gives inwards some small nasal branches,
which supply the membrane of the back part of the roof of the nose and septum, as
well as the membrane covering the end of the Eustachian. tube.
INFERIOR MAXILLARY NERVE. 605
The large superficial petrosal branch of the Vidian nerve, entering the cranium on
the outer side of the carotid artery and beneath the Gasserian ganglion, is directed
backwards in a groove on the petrous portion of the temporal bone to the hiatus
Fallopii, and is thus conducted to the aqueductus Fallopii, where it joins the gangli-
form enlargement of the facial nerve.
The carotid or sympathetic portion of the Vidian nerve, shorter than the other, is
of a reddish colour and softer texture : it is directed backwards, and on the outer
side of the carotid artery ends in the filaments of the sympathetic surrounding that
vessel.
In accordance with the view taken of the ganglia connected with the fifth nerve
(p. 599), the superficial petrosal and carotid parts of the Vidian nerve may be regarded
as the motor and sympathetic roots respectively of the spheno-palatine ganglion; the
spheno-palatiue being its sensory root.
The pharyngeal nerve is inconsiderable in size, and, instead of emanating directly
from the ganglion, is frequently derived altogether from the Vidian. This branch, when
a separate nerve, springs from the back of the ganglion, enters the ptery go-palatine
canal with an artery, and is lost in the lining membrane of the pharynx behind the
Eustachian tube.
Summary. — The superior maxillary nerve, with Meckel's ganglion, supplies
the integument above the zygomatic arch, and that of the lower eyelid, the
side of the nose, and the upper lip ; the upper teeth, the lining mem-
brane of the nose ; the membrane of the upper part of the pharynx, of the
antrum of Highmore, and of the posterior ethmoid cells ; the soft palate,
tonsil, and uvula ; and the glandular and mucous structures of the roof of
the mouth.
INFERIOR MAXILLARY NERVE.
The lower maxillary nerve, the third and largest division of the fifth
nerve, is made up of two portions, unequal in size, the larger being derived
from the Gasserian ganglion, aud the smaller being the slender motor root
of the fifth nerve. These two parts leave the skull by the foramen ovale
in the sphenoid bone, and unite immediately after their exit. A few lines
beneath the base of the skull, and under cover of the external pterygoid
muscle, the nerve separates into two primary divisions, one of which is
higher in position and smaller than the other.
The small, anterior or upper portion, purely motor, terminates in
branches to the temporal, masseter, buccinator, and pterygoid muscles. The
larger or lower portion, chiefly sensory, divides into the auriculo-temporal,
gustatory, and inferior dental branches : it likewise supplies the mylohyoid
muscle, and the anterior belly of the digastric. The branch to the in-
ternal pterygoid muscle, with which also are connected those proceeding
from the otic ganglion to the tensors of the palate and tympanum, is
sometimes counted as a part of the larger division, but is more correctly
regarded as arising from the undivided trunk.
DEEP TEMPORAL, MASSETERIC, BUCCAL, AND PTERYGOID BRANCHES.
The deep temporal branches, two in number, anterior and posteriory pass
outwards above the external pterygoid muscle, close to the bone, and run
upwards, one near the front, and the other near the back of the tem-
poral fossa, beneath the temporal muscle in the substance of which they
are distributed. (See fig. 403.)
The anterior branch is frequently joined with the buccal nerve, and
sometimes with the other deep temporal branch.
The masseteric branch likewise passes above the external pterygoid
606 THE CRANIAL NERVES.
muscle, and is directed nearly horizontally outwards through the sigmoid
notch of the lower jaw to the posterior border of the masseteric muscle,
which it enters on the deep surface. It gives a filament or two to the
articulation of the jaw, and occasionally furnishes a branch to the tem-
poral muscle.
The buccal branch pierces the substance of the external pterygoid muscle,
and courses downwards and forwards to the face, in close contact with the
deep surface of the temporal muscle at its insertion. It furnishes a branch
to the external pterygoid muscle as it pierces it, and on emerging gives
two or three ascending branches to the temporal muscle. It divides into
two principal branches, an upper and a lower, which communicate with the
facial nerve in a plexus round the facial vein, and are distributed to the
integument, the buccinator muscle, and the mucous membrane.
The external pterygoid branch, is most frequently derived from the buccal
nerve. It is sometimes a separate offset from the smaller portion of the
lower maxillary nerve.
The nerve of the internal pterygoid muscle is closely connected at its
origin with the otic ganglion, and enters the inner or deep surface of the
muscle.
AURICFLO-TEMPORAL NERVE.
The auriculo-temporal nerve takes its origin close to the foramen ovale. It
often commences by two roots, Between which may be placed the middle
meningeal artery. It is directed at first backwards, beneath the external
pterygoid muscle, to the inner side of the articulation of the jaw ; then
changing its course, it turns upwards betwt ea the ear and the joint, covered
by the parotid gland ; and emerging from this place, it finally divides iuto
two temporal branches which ascend towards the top of the head.
(a) Communicating branches. — There are commonly two branches which pass
forward round the external carotid artery, and join the facial nerve. Filaments to
the otic ganglion arise near the beginning of the nerve.
(b) Parotid branches are given from the nerve while it is covered by the gland.
(c) Auricular branches. — These are two in number. The lower of the two, arising
behind the articulation of the jaw, distributes branches to the ear below the external
meatus; and sends other filaments round the internal maxillary artery to join the
sympathetic nerve ; the upper branch, leaving the nerve in front of the ear, is dis-
tributed in the integument covering the tragus and the pinna above the external
auditory meatus. Both are confined to the outer surface of the ear.
(d) Branches to the meatus auditorius. — These, two in number, spring from the
point of connection of the facial and auriculo-temporal nerves, and enter the interior
of the auditory meatus between the osseous and cartilaginous parts. One of them
sends a branch to the membrana tympani.
(e) Articular branch. — The nerve to the temporo-maxillary articulation comes
from one of the preceding branches, or directly from the auriculo-temporal nerve.
(/) Temporal branches.— One of these, the smaller and posterior of the two,
distributes filaments to the anterior muscle of the auricle, the upper part of the
pinna and the integument above it. The anterior temporal branch extends with
the superficial temporal artery to the top of the head, and ends in the integument.
It is often united with the temporal branch of the upper maxillary nerve. Meckel
mentions a communication between this branch and the occipital nerve.
GUSTATORY NERVE.
The gustatory nerve, or lingual branch of the fifth, descends under
cover of the external pterygoid muscle, lying to the inner side and in
GUSTATORY XERVE.
607
front of the dental nerve, and sometimes united to it by a cord which
crosses over the internal maxillary artery. It is there joined at an acute
angle by the chorda tympani, a small branch connected with the facial
nerye, which descends from the inner end of the Glasserian. fissure. It
then passes between the internal pterygoid muscle and the lower maxilla,
and is inclined obliquely inwards to the side of the tongue, over the
upper constrictor of the pharynx, (where this muscle is attached to the
maxillary bone,) and above the deep portion of the submaxiliary gland.
Lastly, the nerve crosses Wharton's duct, and is continued along the si<le
of the tongue to the apex, in contact with the mucous membrane of the
mouth.
(a) Communicating branches are given to the submaxiliary ganglion, at the place
Fig. 409.
Fig. 409. — VIEW OF THE BRANCHES OP THE INFERIOR MAXILLARY NERVE FROM THE
OUTER SIDE (from Sapoej after Hirschfeld and Leveille). f
The zygoma and ram us of the jaw have been removed, and the outer plate of the jaw
taken off so as t<i open up the dental canal ; the lower part of the temporal muscle has
been dissected off the bone, and the inasseter muscle turned down.
1, Masseteric branch, descending to the deep surface of the muscle ; 2, a twig to the
temporal muscle ; 5, anterior, and 7, posterior deep temporal nerves ; 3, buccal ; 4, its
union with the facial ; 6, filaments given by the buccal to the external pterygoid muscle ;
8, auriculo-temporal nerve ; 9, its temporal branches; 10, its anterior auricular branches ;
11, its union witli the facial ; 12, gustatory or lingual nerve ; 13, raylo-hyoid nerve ; 14,
inferior dental nerve ; 15, its twigs supplied to the teeth; 16, mental branches; 17, branch
of the facial uniting with the mental.
608 THE CRANIAL NERVES.
where the nerve is in contact with the submaxillary gland. Others form a plexus
with branches of the hypoglossal nerve at the inner border of the hyo-glossus muscle.
(6) Branches to the mucous membrane of the mouth are given from the nerve at
the side of the tongue, and supply also the gums. Some delicate filaments are like-
wise distributed to the substance of the sublingual gland.
(c) The lingual or terminal branches perforate the muscular structure of the tongue,
and divide into filaments, which are continued almost vertically upwards to the conical
and fungiform papillae. Near the tip of the tongue the branches of the gustatory and
hypoglossal nerves are united.
INFERIOR DENTAL NERVE.
The inferior dental nerve is the largest of the three branches of the
lower maxillary nerve. It descends under cover of the external pterygoid
muscle, behind and to the outer side of the gustatory nerve, and, passing
between the ramus of the jaw and the internal lateral ligament of the
temporo-maxillary articulation, enters the inferior dental canal. In com-
pany with the dental artery, it proceeds along this canal, and supplies
branches to the teeth. At the mental foramen it bifurcates ; one part,
the incisor branch, being continued onwards within the bone to the
middle line, while the other, the much larger labial branch, escapes by the
foramsn to the face.
When about to enter the foramen on the inner surface of the ramus of
the jaw, the inferior dental nerve gives off the slender rnylo-hyoid branch.
(a) The mylo-hyoid branch is lodged in a groove on the inner surface of the ramus
of the maxillary bone, in which it is confined by fibrous membrane, and is distributed
to the lower or cutaneous surface of the mylo-hyoideus and to the anterior belly of
the digastric muscle. This nerve may be traced back within the sheath of the inferior
dental to the motor portion of the inferior maxillary nerve.
(b) The dental branches supplied to the molar and bicuspid teeth correspond to the
number of the fangs of those teeth. Each branch enters the minute foramen in the
extremity of a fang, and terminates in the pulp of the tooth. Not unfrequently a
collateral branch supplies twigs to several teeth.
(c) The incisor branch has the same direction as the trunk of the nerve : it extends
to the middle line from the point of origin of the labial branch, and supplies nerves
to the canine and incisor teeth.
(d) The labial or mental branch emerging from the bone by the foramen on the
outer surface, divides beneath the depressor of the angle of the mouth into two
parts.
One of these, the outer division, communicating with the facial nerve, supplies the
depressor anguli oris and orbicularis oris muscles, and the integument of the chin.
The inner portion, the larger of the two, ascends to the lower lip beneath the de-
pressor labii inferioris muscle, to which it gives filaments : the greater number of the
branches end on the inner and outer surfaces of the lip. These inner branches assist
only slightly in forming the plexus of union with the facial nerve.
OTIC GANGLION.
The otic ganglion, or ganglion of Arnold, of a reddish grey colour, is
situated on the deep surface of the lower maxillary trunk, nearly at the
point of junction of the motor fasciculus with that nerve, and around the
origin of the internal pterygoid branch. Its inner surface is close to the
cartilaginous part of the Eustachian tube and the circumflexus palati
muscle ; and behind it is the middle meuingeal artery.
Connection with nerves — roots. — The ganglion is connected with the
lower maxillary nerve, especially with the branch furnished to the internal
pterygoid muscle, and with the auricnlo-teinporal nerve, and thus obtains
motor and sensory roots ; it is brought into connection with the sympa-
OTIC AND SUBMAXILLARY GANGLIA.
609
thetic by a filament from the plexus on the middle meningeal artery.
It likewise receives the small superficial petroaal nerve, which emerges
from the petrous bone by the small foramen internal to the canal of the
tensor tympani muscle, and reaches the exterior of the skull by piercing
the sphenoid bone close to the foramen spinosum. By this nerve the
ganglion forms a communication with the glosso-pharyngeal and facial
nerves.
Fig. 410.— OTIC GANGLTOV Fig. 410.
AKD ITS CONNECT ONS
FKOM THE INSIDE ( lorn
Sappey after Arnold). §
This figure exhibits a
view of the lateral portion
of the skull with a part of
the nasal fossa and lower
jaw of the right side ; the
petrous bone has been re-
moved so as to show the
inner surface of the mein-
brana tympani and the
canal of the facial nerve.
1, smaller motor root of
the fifth nerve passing
down on the inside of the
Gasserian ganglion to unite
with the inferior maxillary
division; 2, inferior denial
nerve entering the canal of
the lower jaw ; 3, njylo-
hyoid branch, seen also
farther down emerging m
front of the internal ptery-
goid muscle ; 4, lingual or gustatory nerve ; 5, chorda tympani ; 6, facial nerve in its
canal ; 7, auriculo-temporal nerve, enclosing in its loop of origin the middle meningeal
artery; 8, otic ganglion; 9, small superficial petrosal nerve joining the ganglion ; 10,
branch to the tensor tympani muscle ; 11, twig connecting the ganglion with the temporo-
auricular nerve ; 12, twig to the ganglion from the sympathetic nerves on the meningeal
artery ; 13, branch to the internal pterygoid muscle ; 14, branch to the tensor palati
muscle.
Branches. — Two small nerves are distributed to muscles — one to the
tensor of the membrane of the tympanum, the other to the circumflexus or
tensor palati.
SUBMAXILLARY GANGLION.
The submaxillary ganglion is placed above the deep portion of the sub-
maxillary gland, and is connected by filaments with the gustatory nerve.
It is about the size of the ophthalmic ganglion. By the upper part or
base it receives branches from nerves which may be regarded as its roots,
whilst from the lower part proceed the filaments which are distributed from
the ganglion.
Connection with nerves — roots. — This ganglion receives filaments from
the gustatory nerve, and likewise, at its back part, a root which appa-
rently comes from the gustatory nerve, but is in reality derived from the
chorda tympani, which is prolonged downwards in the sheath of the
gustatory nerve. It receives also small twigs from the sympathetic filaments
on the facial artery.
Branches. — Some nerves, five or six in number, radiate to the substance
610 THE CRANIAL NERVES.
of the submaxillary gland. Others from the fore part of the ganglion,
longer and larger than the preceding, end in the mucous membrane of the
mouth, and iu Whartou's duct.
According to Meckel (" De quinto pare," &c ), a branch occasionally descends in
front of the hyo-glossus muscle, and after joining with one from the hypoglossal nerve,
ends in the genio-hyo-glossus muscle.
It may be noticed that while the branches from the otic ganglion
pass exclusively to muscles, the submaxillary ganglion gives no muscular
offsets.
Summary. — Cutaneous filaments of the inferior maxillary nerve ramify on
the side of the head, and the external ear, in the auditory passage, the
lower lip, and the lower part of the face ; sensory branches are supplied
by it to the greater part of the tongue ; and branches are furnished to the
mucous membrane of the mouth, the lower teeth and gams, the salivary
glands, and the articulation of the lower jaw.
This nerve supplies the muscles of mastication, viz., the masseter, tem-
poral, and two pterygoid ; also the buccinator, the mylo-hyoid, and the
anterior belly of the digastric ; and from the otic ganglion proceed the
branches to the circumflexus ]_ alati and tensor timpani muscles.
SIXTH PAIR OF NERVES.
The sixth cranial nerve (nerv. abducens) enters the dura mater behind
the dorsum sellae, and passing forwards in the floor of the cavernous sinus,
close to the outer side of the carotid artery, enters the orbit through the
sphenoid al fissure, and between the heads of the external rectus muscle,
and is entirely distributed to that muscle, piercing it on the ocular surface.
In entering the orbit between the heads of the external rectus muscle, it is
beneath the other nerves, but above the ophthalmic vein. While passiiig
along the internal carotid artery in the cavernous sinus, it is joined by several
filaments of the sympathetic from the carotid plexus. According to
Bock, it is joined iu the orbit by a filament from Meckel's ganglion. —
(" Beschreibuug des Funfteu Nervenpaares." 1817.)
SEVENTH PAIR OF NERVES.
In the seventh cranial nerve of Willis are comprised two nerves having
a distinct origin, distribution, and function. One of these, the facial, is the
motor nerve of the face ; the other, the auditory, is the special nerve of the
organ of hearing. Both enter the internal auditory meutus in the tem-
poral bone, but they are soon separated from each other.
FACIAL NERVE.
The facial nerve, or portio dura of the seventh pair, is inclined outwards
with the auditory nerve, from its place of origin, to the internal auditory
meatus. The facial lies in a groove on the auditory nerve, and the tAvo are
united in the auditory meatus by one or two small filaments. At the bot-
tom of the meatus the facial nerve enters the aqueduct of Fallopius, and
follows the windings of that canal to the lower surface of the skull. The
nerve passes through the temporal bone at first almost horizontally outwards,
between the cochlea and vestibule ; on reaching the inner wall of the tyrn-
FACIAL NERVE.
611
pan urn it is turned suddenly backwards above the fenestra ovalis towards the
pyramid. At the place where it bends, the nerve presents a reddish gangli-
furm enlargement, sometimes called the geniculate ganglion, which marks the
place of junction of several nerves. Opposite the pyramid it is arched down-
wards behind the tympanum to the stylo-inastoid foramen, by which it leaves
the osseous canal. It is then continued forwards through the substance of
the parotid gland, and separates iii the gland, behind the ramus of the lower
maxilla, into two primary divisions, the temporo-facial and the cervico-
facial, from which numerous branches spread out over the side of the head,
the face, and the upper part of the neck, forming what is known as the
"pes anserinus."
\Vithin the temporal bone the facial is connected with several other
nerves by separate branches ; and immediately after issuing from the stylo-
mastoid foramen, it gives off three small branches, viz., the posterior
auricular, digastric, and stylo-hyoid.
Fig. 411.— THE FACIAL NKRVB Fig. 411. •
EXPOSED IN ITS CANAL, WITH ITS
CONNECTING BRANCHES, &c.
(from Sappey after Hirschfeld
and Leveille). §
The mastoid and a part of the
petrous bone have been divided
nearly vertically, arid the canal of
the facial nerve opened iu its whole
extent from the meatus internus
to the stylo-mastoid foramen. The
Vidian canal has also been opened
from the outside. 1, facial nerve
in the horizontal part of the com-
mencement of the canal ; 2, its
second part turning backwards ;
3, its vertical portion ; 4, the
nerve at its exit from the stylo-
mastoid foramen ; 5, geniculate
ganglion ; 6, large superficial pe-
trosal nerve passing from this ganglion to the spheno-palatine ganglion, and joined by
the small internal petrosal branch; 7, spheno-palatine ganglion; 8, small superficial
petrosal nerve ; 9, chorda tympani ; 10, posterior auricular branch cut short at its origin ;
11, branch for the digastric muscle ; 12, branch for the stylo-hyoid muscle ; 13, twig to
the stylo-glossus muscle uniting with muscular branches of the glosso-pharyngeal nerve
(14 and 15).
CONNECTING BRANCHES.
Filaments of union with the auditory nerve. — In the meatus auditorius one or two
minute filaments pass between the facial and the trunk of the auditory nerve.
Nerves connected with the gangliform enlargement. — About two lines from the
beginning of the aqueduct of Fallopius, where the facial nerve swells into the gangli-
form enlargement, it is joined by the large superficial petrosal branch from the Vidian
nerve. This ganglion likewise receives a small branch from the small superficial
petrosal nerve which unites the otic ganglion with the tympanic nerve of Jacobson.
The nerve beyond the ganglion receives the external superficial petrosal nerve
(Bidder), which is furnished by the sympathetic accompanying tlie middle meningeal
artery, and enters the temporal bone by a canal external to that traversed by the
small superficial petrosal.
CHOKDA TYMPANI AND NERVE TO THE STAPEDIUS.
The nerve named chorda tympani leaves the trunk of the facial while within its
canal, and crosses the tympanum to join the gustatory nerve, along which it i«> con-
612
THE CRANIAL NEKVES.
ducted towards the tongue. It enters the back part of the tympanic cavity through a
short canal emerging below the level of the pyramid, close to the ring of bone giving
attachment to the membrane of the tympanum ; and being invested by the mucous lining
of the cavity, it is directed forwards across the membrana tympani and the handle of
the malleus, to an aperture at the inner end of the Glaserian fissure. It then passes
downwards and forwards, under cover of the external pterygoid muscle, and uniting
with the gustatory nerve at an acute angle, descends in close contact with it, and is
partly distributed to the submaxillary ganglion and partly blended with the gustatory
nerve in its distribution to the tongue. As this nerve crosses the tympanum, it is
said to supply a twig to the laxator tympaui muscle.
Fig. 412. Fig. 412. — GENICULATE GANGLION OP
THE FACIAL NERVE AND ITS CONNEC-
TIONS FROM ABOVE (from Bidder).
The dissection is made iu the middle
fossa of the skull ou the right side; the
temporal bone being removed so as to
open the meatus iuteruus, hiatus Fal-
lopii, and a part of the caual of the facial
nerve, together with the cavity of the
tympanum, a, the external ear ; b,
middle fossa of the skull with the
meningeal artery ramifying in it ; 1 ,
facial and auditory nerves in the meatus
auditorius internus ; 2, large super-
ficial petrosal nerve ; 3, small super-
ficial petrosal nerve lying over the ten-
sor tyrapani muscle ; 4, the external
superficial petrosal joining sympathetic
twigs on the meningeal artery ; 5, facial
and chorda tympani ; b', nerves of the
eighth pair.
The chorda tympani is regarded by
some anatomists as a continuation of
the great superficial petro.sal nerve.
According to Owen, in the horse and
calf, the portio dura being less dense
in structure, the Yidian branch of the fifth may be distinctly seen crossing
the nerve after penetrating its sheath, and separating into many filaments, with
which filaments of the seventh nerve are blended, Avhile a ganglion is formed
by the superaddition of grey matter ; and the chorda tympani is continued partly
from this ganglion, partly from the portio dura. (Hunter's Collected Works, vol. iv.
p. 194, note.)
The nerve to the stapedius muscle arises from the trunk of the facial
opposite the pyramid, and passes obliquely inwards t j the fleshy belly of
the muscle.
POSTERIOR AURICULAR BRANCH.
This branch arises close to the stylo-mastoid foramen. In front of the
mastoid process, it divides into an auricular and an occipital portion, aud is
connected with the great auricular nerve of the cervical plexus. It is said
to be joined by the auricular branch of the pneumo-gastric nerve.
a. The auricular division supplies filaments to the retrahent muscle of
the ear, and ends in the integument on the posterior aspect of the
auricle.
6. The occipital branch is directed backwards beneath the small occipital
nerve (from the cervical plexus) to the posterior part of the occipito-
TEMPORO-FACIAL DIVISION OF THE FACIAL. 613
frontalis muscle ; it lies close to the bone, and, besides supplying the muscle,
gives upwards filaments to the integument.
DIGASTRIC AND STYLO-HYOID BRANCHES.
The digastric branch arises in common with that for the stylo -hyoid
muscle, and is divided into numerous filaments, which enter the digastric
muscle : one of these sometimes perforates the digastric, and joins the
glospo-pharyngeal nerve near the base of the skull.
The stylo-hyoid branch, long and slender, is directed inwards from the
digastric branch .to the muscle from which it is named. This nerve is
connected with the plexus of the sympathetic on the external carotid
artery.
TEMPORO-FACIAL DIVISION.
The temporo-facial, the larger of the two primary divisions into which
the main trunk of the facial nerve separates, is directed forwards through
the parotid gland. Its ramifications and connections with other nerves form
a network over the side of the face, extending as high as the temple and
as low as the mouth. Its branches are arranged in temporal, malar, and
infraorbital sets.
(a) The temporal branches ascend over the zygoma to the side of the head. Some
end in the anterior muscle of the auricle and the integument of the temple, and
communicate with the temporal branch of the upper maxillary nerve near the ear, as
well as with (according to Meckel) the auriculo-temporal branch of the lower maxil-
lary nerve. Other branches enter the occipito-frontalis, the orbicularis palpebrarum,
and the corrugator supercilii muscles, and join offsets from the supraorbital branch
of the ophthalmic nerve.
(b) The malar bran' lies cross the malar bone to reach the outer side of the orbit, and
supply the orbicular muscle. Some filaments are distributed to both the upper and
lower eyelids : those in the upper eyelid join filaments from the lachrymal and,
supraorbital nerves ; and those in the lower lid are connected with filaments from the
upper maxillary nerve. Filaments from this part of the facial nerve communicate
with the malar branch of the upper maxillary nerve.
(c) The infraorbital brandies, of larger size than the other branches, are almost
horizontal in direction, and are distributed between the orbit and mouth. They
supply the buccinator and orbicularis oris muscles, the elevators of the upper lip and
angle of the mouth, and likewise the integument. Numerous communications take
place with the fifth nerve. Beneath the elevator of the upper lip these nerves are
united in a plexus with the branches of the upper maxillary nerve ; on the side of
the nose they communicate with the nasal, and at the inner angle of the orbit with
the infratrochlear nerve. The lower branches of this set are connected with those of
the cervico-facial division.
Near its commencement the temporo-facial division of the facial is connected with
the auriculo-temporal nerve of the fifth, by one or two branches of considerable size
which turn round the external carotid artery; and it gives some filaments to the
tragus of the outer ear.
CERVICO-FACIAL DIVISION.
This division of the facial nerve is directed obliquely through the parotid
gland towards the angle of the lower jaw, and gives branches to the face,
below those of the preceding division, and to the upper part of the neck.
The branches are named buccal, supramaxillary, and inframaxillary. In the
gland, this division of the facial nerve is joined by filaments of the great
auricular nerve of the cervical plexus, and offsets from it penetrate the sub-
stance of the gland.
614
THE CRANIAL NERVES.
(a) The buccal branches are directed across the masseter muscle to the angle of
the mouth ; supplying the muscles, they communicate with the temporo-facial divi-
sion, and on the buccinator muscle join with filaments of the buccal branch of the
lower maxillary nerve.
Fig. 413.
Fig. 413. — SUPERFICIAL DISTRIBUTION OP THE FACIAL, TRIGEMINAL, AND OTHER NKRVES
OF THE HEAD (from Sappey after Hirschfeld and Leveille). f
a, References to the Facial Nerve. — 1, trunk of the facial nerve after its exit from the
stylo-mastoid foramen ; 2, posterior auricular branch ; 3, filament of the great auricular
nerve uniting with the foregoing ; 4, twig to the occipitalis muscle ; 5, twig to the posterior
auricular muscle ; 6, twig to the superior auricular muscle ; 7, branch to the digastric; 8,
that to the stylo-hyoid muscle ; 9, superior or temporo-facial division of the pes anseririus ;
10, temporal branches; 11, frontal ; 12, palpebral or orbital ; 13, nasal or infraorbital ;
14, buccal ; 15, inferior or cervico-facial division of the nerve ; 16, labial and mental
branches ; 17, cervical branches.
by References to the Fifth Nerve. — 18, temporo-auricular nerve (of the inferior maxillaiy
nerve) uniting with tin- facial, giving anterior auricular and parotid branches, and ascend-
ing to the temporal region ; 19, external frontal or supra-orbital nerve ; 20, internal
frontal ; 21, palpebral twigs of the lachrymal ; 22, terminal branches of the infra-
trochlear ; 23, malar twig of the orbito-malar ; 24, external nasal twig of the ethmoidal ;
25, infraorbital nerve ; 26, buccal nerve uniting with branches of the facial ; 27, labial
and mental branches of the inferior dental nerve.
c, Cervical Nerves. — 28, great occipital nerve from the second cervical ; 29, great
auricular nerve from the cervical plexus ; 30, lesser occipital ; 31, another branch with a
similar distribution ; 32, superficial cervical, uniting by several twigs with the facial.
AUDITORY NERVE.— EIGHTH PAIR. 615
(b) The supramaxiUary branch, sometimes double, gives an offset over the side of
the maxilla to the angle of the mouth, and is then directed inwards, beneath the
depressor of the angle of the mouth, to the muscles and integument between the lip
and chin ; it joins with the labial branch of the lower dental nerve.
(c) The inframaxillary branches (r. subcutanei colli), perforate the deep cervical
fascia, and, placed beneath the platysma muscle, form arches across the side of the
neck as low as the hyoid bone. Some branches join the superficial cervical nerve
beneath the platysma, others enter that muscle, and a few perforate it to end in the
integument.
Summary. — The facial nerve is the motor nerve of the face. It is
distributed to most of the muscles of the ear, and to the muscles of the
scalp ; to those of the mouth, nose, and eyelids ; aud to the cutaneous
muscle of the neck (platysma). It likewise supplies branches to the integu-
ment of the ear, to that of the side and back of the head, as well as to that
of the face and the upper part of the neck.
This nerve is connected freely with the three divisions of the fifth nerve,
and with the submaxillary and spheno-palatine ganglia ; with the glosso-
pharyngeal and pneuino-gastric nerves : with the auditory, and with parts
of the sympathetic and the spinal nerves.
AUDITORY NERVE.
The auditory nerve, or portio mollis of the seventh pair, is the special nerve
of the organ of hearing, and is distributed exclusively to the internal ear.
As the auditory nerve is inclined outwards from its connection with the
medulla oblongata to gain the internal auditory meatus, it is in contact
with the facial nerve, being only separated from it in part by a small artery
destined for the internal ear. Within the meatus the two nerves are con-
nected to each other by one or two small filaments. Finally the auditory
nerve bifurcates in the meatus : one division, piercing the anterior part of
the cribriform lamina, is distiibuted to the cochlea ; the other, piercing the
posterior half of the lamina, enters the vestibule of the internal ear. The
distribution of these branches will be described with the ear.
EIGHTH PAIR OF NERVES.
The eighth pair is composed of three distinct nerves — the glosso-pharyn-
geal, pneumo-gastric, and spinal accessory, which leave the skull through the
anterior and inner division of the foramen lacerum posticum, to the inner
side and in front of the internal jugular vein. Two of these nerves, the
glosso-pharyngeal and pneumo-gastric, are attached to the medulla oblongata
in the same line, and resemble one another somewhat in their distribution,
for both are distributed to the first part of the alimentary canal. The other,
the spinal accessory, takes its origin chiefly from the spinal cord, and is
mainly distributed to muscles ; but it gives fibres to the first two nerves by
its communicating branch.
GLOSSO-PHARYNGEAL NERVE.
The glosso-pharyngeal nerve is destined, as the name implies, for the
tongue and pharynx. Directed outwards from its place of origin over the
flocculus to the foramen jngulare, it leaves the skull with the pneumo-gastric
and spinal- accessory nerves, but in a separate tube of dura mater. In passing
through the foramen, somewhat in front of the others, this nerve is
contained in a groove, or in a canal in the lower border of the petrous
616
THE CRANIAL NERVES.
portion of the temporal bone, and presents, successively, two ganglionic
enlargements, — the jugular ganglion, and the petrous ganglion.
After leaving the skull, the glosso-pharyngeal nerve appears between the
internal carotid artery and the jugular vein, and is directed downwards over
the carotid artery and beneath the styloid process and the muscles con-
nected with it, to the lower border of the stylo-pharyngeus muscle. Here,
changing its direction, the nerve curves inwards to the tongue, on the
stylo-pharyngeus and the middle constrictor muscle of the pharynx, above
the upper laryngeal nerve ; and, passing beneath the hyo-glossus muscle,
ends in branches for the pharynx, the tonsil, and the tongue.
Fig. 414. Fig. 414. — DIAGRAMMATIC! SKETCH
PROM BEHIND OF THE ROOTS OF THE
NERVES OF THE EIGHTH PAIR, WITH
THEIR GANGLIA AND COMMUNICA-
TIONS (from Beudz).
A, part of the cerebellum above the
fourth ventricle ; B, medulla oMon-
gata; C, posterior columns of the spinal
cord ; 1, root of the glosso-pharyngeal
nerve ; 2, roots of the pneumo-gastric ;
3, 3, 3, roots of the spinal accessory,
the uppermost number indicating the
filaments intermediate between the
spinal accessory and pneumo-gastric ;
4, jugular ganglion of the glosso-pha-
ryngeal ; 5, petrous ganglion ; 6,
tympanic branch ; 7, ganglion of the
root of the pneurao-gastric ; 8, auri-
cular branch ; 9, long ganglion on the
trunk of the pneumo-gastric; 10,
branch from the upper ganglion to the
petrous ganglion of the glosso-pharyn-
geal ; 11, inner portion of the spinal
accessory ; 12, outer portion ; 13,
pharyngeal branch of the pneumo-
gastric ; 14, superior laryngeal
branch ; 15, twigs connected with the sympathetic ; 16, fasciculus of the spinal accessory
prolonged with the pneumo-gastric.
The jugular ganglion, the smaller of the two ganglia of the glosso-
pharyngeal nerve, is situated at the upper part of the osseous groove in
which the nerve is laid during its passage through the jugular foramen.
Its length is from half a line to a line, and the breadth from half to three
fourths of a line. It is placed on the outer side of the trunk of the nerve,
and involves only a part of the fibres, — a small fasciculus passing over the
ganglion, and joining the nerve below it.
The petrous ganglion is contained in a hollow in the lower border of the
petrous part of the temporal bone (receptaculuin ganglioli petrosi), and
measures about three lines in length. This ganglion includes all the fila-
ments of the nerve, and resembles the gangliform enlargement of the facial
nerve. From, it arise the small branches by which the glosso-pharyngeal is
connected with other nerves at the base of the skull : these are the tympanic
nerve, and the branches which join the pneumo-gastric and sympathetic.
CONNECTING BEANCHES, AND TYMPANIC BRANCH.
From the petrous ganglion spring three small connecting filaments. One passes
to the auricular branch of the pneumo-gastric, one to the upper ganglion of the sym-
GLOSSO-PHARYXGEAL NERVE.
617
pathetic or vice versd, and a third to the ganglion of the root of the pneumo -gastric
nerve. The last is not constant.
There is sometimes likewise a filament from the digastric branch of the facial nerve,
which, piercing the digastric muscle, joins the glosso-pharyngeal nerve below the
petrous ganglion.
The tympanic branch (nerve of Jacobson), arises from the petrous ganglion, and is
conducted to the tympanum by a special canal, the orifice of which is in the ridge of
bone between the jugular fossa and the carotid foramen. On the inner wall of the
tympanum the nerve joins with a twig from the sympathetic in a plexus (tym-
panic), and distributes filaments to the membrane lining the tympanum and the
Eustachian tube, as well as one to the fenestra rotunda, and another to the fenestra
ovalis.
Fig. 415
Fig. 415. — SKETCH OP THE TYMPANIC
BRANCH OF THE GLOSSO-PHARYN-
GEAL NERVE, AND ITS CONNECTIONS
(from Breschet).
A, squamous part of the left tem-
poral bone ; B, petrous part ; C, in-
ferior maxillary nerve ; D, internal
carotid artery ; a, tensor tympani
muscle ; 1, carotid plexus ; 2, otic
ganglion ; 3, glosso-pharyngeal nerve ;
4, tympanic nerve ; 5, twigs to the
carotid plexus ; 6, twig to fenestra
rotunda ; 7, twig to fenestra ovalis ;
8, junction with the large superficial
petrosal nerve ; 9, small superficial
petrosal ; 10, twig to the tensor tym-
pani muscle; 11, facial nerve; 12,
chorda tyrapani ; 13, petrous ganglion
of the glosso-pharyngeal ; 14, twig to
the membrane of the Eustachian tube.
From the tympanic nerve are
given three connecting branches,
by which it communicates with
other nerves; and which occupy
channels given off from the osseous
canal through which the nerve enters the tympanum. One branch enters the carotid
canal and joins with the (sympathetic on the carotid artery. A second is united to
the large superficial petrosal nerve, as this lies in the hiatus Fallopii. And the
third is directed upwards, beneath the canal for the tensor tympani muscle, towards
the surface of the petrous portion of the temporal bone, where it becomes the small
petrosal nerve; and under this name it is continued to the exterior of the skull
through a small aperture in the sphenoid and temporal bones, to end in the otic
ganglion. As this petrosal nerve passes the gangliform enlargement of the facial, it
has a connecting filament with that enlargement, which is by some considered its
principal posterior termination.
Jacobson described an anterior or internal branch from the tympanic nerve to the
spheno-palatine ganglion.
BRANCHES DISTRIBUTED IN THE NECK.
The carotid branches course along the internal carotid artery, and unite with the
pharyngeal branch of the pneumo-gastric, and with branches of the sympathetic.
The pharyngeal branches, three or four in number, unite opposite the middle con-
strictor of the pharynx with branches of the pneumo-gastric and sympathetic to form
the pharyngeal plexus. Nerves to the mucous membrane of the pharynx perforate
the muscles, and extend upwards to the base of the tongue and the epiglottis, and
downwards nearly to the hyoid bone.
618 THE CRANIAL NERVES.
The muscular branches are given to the stylo-pharyngeus and constrictor
muscles.
Tonsilitic brandies. — When the glosso-pharyngeal nerve is near the tonsil, some
branches are distributed on that body in a kind of plexus (circulus tonsillaris). From
these nerves offsets are sent to the soft palate and the isthmus of the fauces.
Lingual branches. — The glosso-pharyngeal nerve divides into two parts at the
border of the tongue. One turns to the upper surface of the tongue, supplying the
mucous membrane at its base ; the other perforates the muscular structure, and ends
in the mucous membrane on the lateral part of the tongue. Some filaments enter
the circumvallate papillae.
Summary. — The glosso-pharyngeal nerve distributes branches to the
mucous membrane of the tongue, pharynx, tympanum, and Eustachian tube.
The muscles supplied by it are some of those of the pharynx and base of the
tongue. It is connected with the following nerves, viz., the lower maxillary
division of the fifth, the facial, the pneumo-gastric (the trunk and branches
of this nerve), and the sympathetic.
PNEUMO-GASTRIC NERVE.
The pneumo-gastric nerve (nervus vagus, par vagum) has the longest
course of any of the cranial nerves. It extends through the neck and the
cavity of the chest to the upper part of the abdomen ; and it supplies nerves
to the organs of voice and respiration, to the alimentary canal as far as the
stomach, and to the heart.
The filaments by which this nerve springs from the medulla oblongata
are arranged in a flat fasciculus, immediately beneath the glosso-pharyngeal
nerve, and directed outwards with that nerve, across the flocculus to the
jugular foramen.
In passing through the opening at the base of the skull the pneumo-
gastric nerve is contained in the same sheath of dura mater, and surrounded
by the same tube of arachnoid membrane as the spinal-accessory nerve ; but
it is separated from the glosso-pharyngeal nerve by a process of membrane.
In the foramen the filaments of the nerve become aggregated together ; and
it here presents a ganglionic enlargement, distinguished as the ganglion of
the root of the pneumo-gastric. After its passage through the foramen, it
is joined by the accessory part of the spinal accessory nerve, and a second
ganglion is formed upon it, the ganglion of the trunk of the nerve. Several
communications are at the same time established with the surrounding
nerves.
The upper ganglion, or ganglion of the root of the pneumo-gastric nerve,
situated in the foramen jugulare, is of a greyish colour, nearly spherical, and
about two lines in diameter ; it has filaments connecting it with other nerve*,
viz., with the facial, the petrous ganglion of the glosso-pharyngeal, the
spinal accessory, and the sympathetic.
The lower ganglion, or ganglion of the trunk or the pneumo-gastric nerve,
is about half an inch below the preceding. Occupying the trunk of the
nerve outside the skull, it is of a flattened cylindrical form and reddish
colour, and measures about ten lines in length and two in breadth. The
ganglion does not include all the fibres of the nerve; the fasciculus, which
is sent from the spinal accessory to join the vagus, is the part not in-
volved in the ganglionic substance. It communicates with the hypoglossal,
the spinal, and the sympathetic nerves.
The pneumo-gastric nerve descends in the neck, between and concealed
PXEUMO-GASTRIC NERVE.
619
by the internal jugular vein and the internal carotid artery, and afterwards
similarly between that vein and the common carotid artery, being enclosed
along with them in the sheath of the vessels. As they enter the thorax,
the nerves of the right and left side present some points of difference.
Fig 416. — DIAGRAM OF THE ROOTS Fig. 416.
AND ANASTOMOSING BRANCHES OF
THE NERVES OF THE EIGHTH PAIR
AND NEIGHBOURING NERVES (from
Sappey after Hirschfeld and Le-
veille).
1, facial nerve ; 2, glosso-pharyn-
geal with the petrous ganglion repre-
sented ; 2', connection of the digastric
branch of the facial neive with the
glosso-pharyngeal nerve ; 3, pneu-
mo-gastric, with both its ganglia re-
presented ; 4, spinal access ry ; 5,
hypoglossal ; 6, superior cervical
ganglion of the sympathetic ; 7, loop of
union between the two first cervical
nerves ; 8, carotid branch of the sym-
pathetic ; 9, nerve of Jacobson (tym-
panic), given off from the petrous
ganglion ; 10, its filaments to the
sympathetic; 11, twig to the Eusta-
chian tube ; 12, twig to the fenestra
ovalis; 13, twig to the fenestra ro-
tun'la ; 14, twig of union with the
small superficial petrosal ; 15, twig of
union with the large superficial petro-
s tl ; 16, otic ganglion ; 17, branch of
the jugular fossa, giving a filament to
the petrous ganglion ; 18, union
of the spinal accessory with the pneu-
mo-gastric ; 19, union of the hypo-
glossal with the first cervical nerve ;
20, union between the sterno-mastoid
branch of the spinal accessory and
that of the second cervical nerve ; 21,
pharyngeal plexus ; 22, superior laryngeal nerve ; 23, external laryngeal ; 24, middle
cervical ganglion of the sympathetic.
On the rirjht side the nerve crosses over the first part of the right sub-
clavian artery, at the root of the neck, and its recurrent laryngeal branch
turns backwards and upwards round that vessel. The n rve then enters
the thorax behind the right innominate vein, and descends on the side of the
trachea to the back of the root of the lung, where it spreads out in the pos-
terior pulmonary plexus. It emerges from this plexus in the form of two
cords, which are directed to the resophagus. and uniting and subdividing
form, with similar branches of the nerve of the left side, the oesophageal
plexus. Near the lower part of the oesophagus the branches, which have
thus interchanged fibres with the nerve of the left side, are gathered
again into a single trunk, which, descending on the back of the oesophagus,
is spread out on the posterior or inferior surface of the stomach.
On the left side the pueumo-gastric nerve, entering the thorax between
the left carotid and subclavian arteries and behind the left innominate vein,
lies further forwards than the right nerve, and crosses over the arch of the
aorta, while its recurrent laryngeal branch turns up behind the arch. It
s s 2
620
THE CRANIAL NERVES.
then passes behind the root of the left lung, and, emerging from the
posterior pulmonary plexus, is distributed like its fellow to the oesophagus.
Fig. 417.
Fig. 417.— VIEW OP THE NERVES OP THE EIGHTH PAIR, THEIR DISTRIBUTION AND
CONNECTIONS ON THE LEFT SIDE (from Sappey after Hirschfeld and Leveilld). 3
1, pneumo-gastric nerve in the neck ; 2, ganglion of its trunk ; 3, its union with the
spinal accessory ; 4, its union with the hypoglossal ; 5, pharyngeal branch ; 6, superior
laryngeal nerve ; 7, external laryngeal ; 8, laryngeal plexus ; 9, inferior or recur-
rent laryngeal ; 10, superior cardiac branch; 11, middle cardiac; 12, plexiform part
of the nerve in the thorax; 13, posterior pulmonary plexus ; 14, lingual or gustatory
nerve of the inferior maxillary ; 15, hypoglossal, passing into the muscles of the tongue,
giving its thyro-hyoid branch, and uniting with twigs of the lingual ; 16, glosso-pharyngeal
nerve; 17, spinal accessory nerve, uniting by its inner branch with the pneumo-gastric,
and by its outer, passing into the sterno-mastoid muscle ; 18, second cervical nerve ; 19,
third; 20, fourth; 21, origin of the phrenic nerve; 22, 23, fifth, sixth, seventh, and
eighth cervical nerves, forming with the first dorsal the brachial plexus ; 24, superior
cervical ganglion of the sympathetic ; 25, middle cervical ganglion ; 26, inferior cervical
ganglion united with the first dorsal ganglion; 27, 28, 29, 30, second, third, fourth, and
fifth dorsal ganglia.
PNEUMO-GASTR1C XERVE. 621
Inferiorly, it forms a single trunk in front of the oesophagus, and is spread
out on the anterior or superior surface of the stomach.
There are various circumstances in the distribution of the pneumo-gastric nerves
which at first sight appear anomalous, but which are explained by reference
to the process of development. The recurrent direction of the inferior laryngeal
branches in all probability arises from the extreme shortness or rather absence of the
neck in the embryo at first, and from the branchial arterial arches having originally
occupied a position at a higher level than the parts in which those branches are
ultimately distributed, and having dragged them down as it were in the descent of
the heart from the neck to the thorax. The recurrent direction may therefore be
accepted as evidence of the development of those nerves before the occurrence of
that descent. The circumstance that one recurrent laryngeal nerve passes round the
subclavian artery, and the other round the aorta, is seen to arise from an originally
symmetrical disposition, when it is remembered that the innominate artery and the
arch of the aorta are derived from corresponding arches of the right and left sides.
The supply of the back of the stomach by the right pneumo-gastric nerve, and of the
front by the left nerve, is connected with the originally symmetrical condition of the
alimentary canal, and the turning over of the stomach on its right side in its sub-
sequent growth.
BRANCHES OF THE PNEUMO-GASTRIC NERVE.
Some of its branches serve to connect the pneumo-gastric with other
nerves, and others are distributed to the muscular substance or the mucous
lining of the organs which the nerve supplies. The principal con-
necting branches of this nerve are derived from the ganglia. In the
different stages of its course branches are supplied to various organs aa
follows. In the jugular foramen, a branch is given to the ear ; in the neck,
branches are furnished successively to the pharynx, the larynx, and the
heart ; and in the thorax, additional branches are distributed to the heart,
as well as to the lungs and the oesophagus. Terminal branches in the
abdomen are distributed to the stomach, liver, and other organs.
CONNECTING BRANCHES AND AURICULAR BRANCH.
Connections between the upper ganglion of the vagus nerve and the spinal accessory,
glosso-pharyngeal, and sympathetic nerves. — The connection with the spinal accessory
is effected by one or two filaments. The filament to the petrous ganglion of the
glosso-pharyngeal is directed transversely ; it is not always present. The communi-
cation with the sympathetic is established by means of the ascending branch of the
upper cervical ganglion.
The auricular branch is continued to the outer ear. Arising from the ganglion of
the root, this branch is joined by a filament from the glosso-pharyngeal nerve, and
then turns backwards along the outer boundary of the jugular foramen to an opening
near the styloid process. Next, it traverses the substance of the temporal bone,
crossing the aqueduct of Fallopius, about two lines from the lower end, and, reaching
the surface between the mastoid process and the external auditory meatus, is distri-
buted to the integument of the back of the ear. On the surface it joins with a twig
from the posterior auricular branch of the facial nerve.
Connections of the second ganglion with the hypoglossal, sympathetic, and spinal
nerves. — This ganglion is connected by filaments with the trunk of the hypoglossal,
with the upper cervical ganglion of the sympathetic, and with the loop formed between
the first two cervical nerves.
PHARYNGEAL BRANCH.
The pharyngeal branch arises from the upper part of the ganglion of the
trunk of the nerve. In its progress inwards to the pharynx this nerve
crosses in some cases over, in others under the internal carotid artery ; and
622 THE CRANIAL NERVES.
it divides into branches, which, conjointly with others derived from the
glosso-pharyngeal, the superior laryngeal, and the sympathetic nerves, form
a plexus (pharyngeal) behind the middle constrictor of the pharynx. From
the plexus branches are given to the muscular structure, and to the mucous
membrane of the pharynx. As the pharyngeal nerve crosses the carotid
artery, it joins filaments which the glosso-pharyngeal distributes on the same
vessel. — There is sometimes a second pharyngeal branch.
SUPERIOR PHARYNGEAL BRANCH.
This nerve springs from the middle of the ganglion of the trunk of the
pneumo-gastric nerve. It is directed inwards to the larynx beneath the
internal carotid artery, and divides beneath that vessel into two branches,
distinguished as external and internal laryngeal, both of which ramify in
the structures of the larynx.
The external laryngeal branch, the smaller of the two divisions, gives
backwards, at the side of the pharynx, filaments to the pharyugeal plexus
and the lower constrictor muscle ; and it is finally prolonged beneath the
muscles on the side of the larynx to the crico thyroid muscle in which it
ends. In the neck this branch joins the upper cardiac nerve of the
sympathetic.
The internal laryngeal branch is continued to the interval between the
hyoid bone and the thyroid cartilage, where it perforates the thyro-hyoid
membrane with the laryngeal branch of the superior thyroid artery, and dis-
tributes filaments to the mucous membrane : some of these are directed up-
wards in the aryteno-epiglottidean fold of mucous membrane to the base of the
tongue, the epiglottis, and the epiglottidean glands; while others are reflected
downwards in the lining membrane of the larnyx, extending to the corda
vocalis, on the inner side of the laryngeal pouch. A slender communicating
branch to the recurrent laryngeal nerve descends beneath the lateral part of
the thyroid cartilage. A branch enters the arytenoid muscle, some fila-
ments of which seem to end in the muscle, while others proceed through
it to the mucous membrane.
RECURRENT LARYNGEAL BRANCH.
The recurrent or inferior laryngeal branch of the vagus nerve, as the
name expresses, has a reflex course to the larnyx.
The nerve on the right side arises at the top of the thorax, winds round
the subclavian artery, and passes beneath the common carotid and inferior
thyroid arteries in its course towards the trachea. On the left side the re-
current nerve is bent round, below and behind the arch of the aorta, imme-
diately beyond the point where the obliterated ductus arteriosus is con-
nected with the arch, and is thence continued upwards to the trachea.
Each nerve in its course to the larynx is placed between the trachea and
oesophagus, supplying branches to both tubes ; and each, while making its
turn round the artery, gives nerves to the deep cardiac plexus. At the
lower part of the cricoid cartilage the recurrent nerve distributes branches
to supply all the special muscles of the larynx, except the crico-thyroid
muscle, which is supplied from the upper laryngeal nerve. It likewise
gives a few offsets to the mucous membrane, and a single communicating
filament which joins the long branch of the upper laryngeal nerve beneath
the side of the thyroid cartilage.
BRANCHES OF PNEUMO-GASTRIC NERVE. 623
CARDIAC BRANCHES.
Branches to the heart are given off by the pneumo-gastric nerve both in
the neck and in the thorax.
The cervical cardiac branches arise at both the upper and the lower part
of the neck. The upper branches are small, and join the cardiac nerves of
the sympathetic. The loiver, a single branch, arises as the pneumo-gastric
nerve is about to enter the chest. On the right side this branch lies by the
side of the innominate artery, and joins one of the cardiac nerves destined
for the deep cardiac plexus ; it gives some filaments to the coats of the
aorta. The branch of the left side crosses the arch of the aorta, and ends
in the superficial cardiac plexus.
The thoracic cardiac branches of the right side leave the trunk of the
pneumo-gastric as this nerve lies by the side of the trachea, and some
are also derived from the first part of the recurrent branch : they pass
inwards on the air- tube, and end in • the deep cardiac plexus. The
corresponding branches of the left side come from the left recurrent
laryngeal nerve.
PULMONARY BRANCHES.
Two sets of pulmonary branches are distributed from the pneumo-gastric
nerve to the lung ; and they reach the root of the lung, one on its fore part,
the other on its posterior aspect. The anterior pulmonary nerves, two or
three in number, are of small size. They join with filaments of the
sympathetic ramified on the pulmonary artery, and with these nerves
constitute the anterior pulmonary plexus. Behind the root of the lung the
pneumo-gastric nerve becomes flattened, and gives several branches of much
larger size than the anterior branches, which, with filaments derived from
the second, third, and fourth thoracic ganglia of the sympathetic, form the
posterior pulmonary plexus. Offsets from this plexus extend along the rami-
fications of the air-tube through the substance of the lung.
CESOPHAGEAL BRANCHES.
The oesophagus within the thorax receives branches from the pneumo-
gastric nerves, both above and below the pulmonary branches. The lower
branches are the larger, and are derived from the cesophageal plexus, formed
by connecting cords between the nerves of the right and left sides, while
they lie in contact with the oesophagus.
GASTRIC BRANCHES.
The branches distributed to the stomach (gastric nerves) are the terminal
branches of bath pneumo-gastric nerves. The nerve of the left side, on
arriving in front of the oesophagus, opposite the cardiac orifice of the
stomach, divides into many branches : the largest of these extend over the fore
part of the stomach ; others lie along its small curvature, and unite with
branches of the right nerve and the sympathetic ; and some filaments are
continued between the layers of the small omentum to the hepatic plexus.
The right pneumo-gastric nerve descends to the stomach on the back of the
gullet and distributes branches to the posterior surface of the organ : a part
of this nerve is continued from the stomach to the left side of the coeliac
plexus, and to the splenic plexus of the sympathetic.
Summary. — The pneumo-gastric nerves supply branches to the upper part
of the alimentary canal, viz., the pharynx, oesophagus, and stomach with
the liver and spleen ; and t6 the respiratory passages, namely, the larynx,
Fig. 418.
40 23 24 26 0 .
PXEUMO-GASTRIC.-SPINAL ACCESSORY NERVE. 625
Fig. 418. — VIEW OF THE DISTRIBUTION AND CONNECTIONS OP THE PNEUMO-GASTRIO AND
SYMPATHETIC NERVES ON THE RIGHT SIDE (from Hirschfeld and Leveille). f
a, lachrymal gland ; b, sublingual gland ; c, submaxillary gland and facial artery ;
d, thyroid gland, pulled forwards by a hook ; e, trachea, below which is the right
bronchus cut across; /, the gullet; g, the stomach, divided near the pylorus ; i, trans-
verse colon, with some folds of intestine below.
A, heart, slightly turned aside to show the cardiac plexus, &c. ; B, aortic arch, drawn
forward by a hook ; C, innominate artery ; D, subclavian artery, of which a portion has
been removed to show the sympathetic ganglia ; E, inferior thyroid artery ; F, a divided
part of the external carotid artery, upon which runs a nervous plexus ; Q-, internal
carotid, emerging from its canal superiorly; H, thoracic aorta; K, intercostal vein; L,
pulmonary trunk, the right branch cut ; M, superior vena cava ; 0, intercostal artery.
1, ciliary nerves of the eyeball ; 2, branch of the oculo-motor to the inferior oblique
muscle, connected with the ophthalmic ganglion ; 3, 3, 3, the three principal divisions of
the trifacial nerve ; 4, ophthalmic ganglion ; 5, spheno-palatine ; 6. otic ; 7, submaxillary ;
8, sublingual ; 9, sixth nerve ; 10, facial in its canal, uniting with the spheno-palatine
and otic ganglia; 11, glosso-pharyngeal; 12, right pneumo-gastric ; 13, left pneumo-
gastric spreading on the anterior surface of the stomach ; 14, spinal accessory ; 35, hypo-
glossal ; 16, lower nerve of the cervical plexus; 17, middle nerve of the brachial
plexus ; 18, intercostal nerves ; 21, superior cervical ganglion of the sympathetic, con-
nected with, 22, tympanic nerve of Jacobson ; 23, carotid branch of the Vidian nerve ;
24, cavernous plexus; 25, ophthalmic twig; 26, filament to the pituitary gland; 27,
union with the upper cervical nerves ; 28, points to the pneurao-gastric nerve, close to
the pharyngeal and carotid branches : 29, points to the superior laryngeal nerve, close
to the pharyngeal and inter-carotid plexuses ; 30, laryngeal branch joining the laryngeal
plexus ; 31, great sympathetic nerve ; 32, superior cardiac nerve ; 33, middle cervical
ganglion ; 34, twig connecting the ganglion with, 35, the recurrent ; 36, middle cardiac
nerve ; 37, great sympathetic nerve ; 38, inferior cervical ganglion ; below 37, branches
from the ganglion, passing round the subclavian and vertebral arteries ; 39, the line from
this number crosses the nerves proceeding from the brachial plexus ; 40, sympathetic
twigs surrounding the axillary artery ; 41, branch of union with the first intercostal
nerve ; the line from the letter e, pointing to the trachea, crosses the superior, middle,
and inferior cardiac nerves ; 42, cardiac plexus and ganglion ; 43, 44, right aud left coro-
nary plexuses ; 45, 46, thoracic portion of the great sympathetic nerve and ganglia, showing
their connections with the intercostal nerves ; 47, great splanchnic nerve; 48, semilunar
ganglion ; 49, lesser splanchnic ; 50, solar plexus ; 51, union with the pneumo-gastric
nerve ; 52, diaphragmatic plexus and ganglion ; 53, coronary plexus ; 54, hepatic ; 55,
splenic ; 56, superior mesenteric ; 57, renal plexus.
trachea, and its divisions in the lungs. These nerves give branches likewise
to the heart and great vessels by means of their communication with the
cardiac plexus. Each pneumo-gastric nerve is connected with the following
cranial nerves — the spinal accessory, glosso-pharyngeal, facial, and hypo-
glossal ; also, with some spinal nerves ; and with the sympathetic in the
neck, thorax, and abdomen.
SPINAL ACCESSORY NERVE.
The spinal nerve accessory to the vagus, or, as it is shortly named, the
spinal accessory nerve, consists of two parts : one (accessory) joins the
trunk of the pneumo-gastric ; the other (spinal) ends in branches to the
stern o-mastoid and trapezius muscles.
The internal or accessory part, the smaller of the two, joins in the foramen
of exit the ganglion on the root of the pneumo-gastric, by two or three
filaments ; and having passed from the skull, blends with the trunk of the
pneumo-gastric beyond its second ganglion, as already said.
It is stated by Bendz that a filament is given from the spinal accessory to the pha-
ryngeal nerve above the place of junction with the pneumo-gastric, and that fibrils of
the same nerve have been traced into each of the muscular offsets of the pneumo-
gastric nerve. (Bendz, " Tract, de connexu inter nerv. vag. et acces." 1836.)
The external portion of the nerve communicates with the accessory part
626 THE CRANIAL NERVES.
in the foramen j ugulare. After issuing from the foramen, the nerve is directed
backwards across the internal jugular vein, in some cases over, in others under
it, and perforates the sterno-mastoid muscle, supplying this with branches,
and joining amongst the fleshy fibres with branches of the cervical plexus.
Descending in the next place across the neck behind the sterno-mastoid, the
nerve passes beneath the trapezius muscle. Here it forms a kind of plexus
with branches of the third and fourth cervical nerves, and distributes fila-
ments to the trapezius, which extend nearly to the lower edge of the muscle.
NINTH PAIR OF NERVES.
The hypoglossal or ninth cranial nerve is the motor nerve of the tongue,
and in part of some muscles of the neck.
The filaments by which this nerve arises from the medulla oblongata are
collected into two bundles, which converge to the anterior condyloid
foramen of the occipital bone. Each bundle of filaments perforates the
dura mater separately within the foramen, and the two are joined after
they have passed through it.
After leaving the cranium, this nerve descends almost vertically to the
lower border of the digastric muscle, whera, changing its course, it is
directed forwards above the hyoid bone to the under part of the tongue,
It lies at first very deeply with the vagus nerve, to which it is connected ;
but passing between the internal carotid artery and the jugular vein, it
curves forward round the occipital artery, and then crosses over the external
carotid below the digastric muscle. Above the hyoid bone it is crossed by
the lower part of the stylo-hyoid muscle and posterior belly of the digastric,
and rests on the hyo-glossus muscle. At the anterior border of the hyo-
glossus it is connected with the gustatory nerve, and is continued in the
fibres of the genio-hyo-glossus muscle beneath the tongue to the tip,
distributing branches upwards to the muscular substance.
The principal branches of this nerve are distributed to the muscles
ascending to the larynx and hyoid bone, and to those of the tongue ; a few
serve to connect it with some of the neighbouring nerves.
In animals the ninth nerve not unfrequently possesses a posterior root furnished with
a ganglion, in the same manner as that of a spinal nerve.
CONNECTING BRANCHES.
Connection with the pneumo-gastric. — Close to the skull the hypoglossal nerve is
connected with the second ganglion of the pneumo-gastric by separate filaments, or
in some instances the two nerves are united so as to form one mass.
Union with the sympathetic and first two spinal nerves. — Opposite the first cervical
vertebra the nerve communicates by several twigs with the upper cervical ganglion
of the sympathetic, and with the loop uniting the first two spinal nerves in front of
the atlas.
MUSCULAR AND LINGUAL BRANCHES.
Descending branch of the ninth nerve. — This branch (r. descendens noni),
leaves the ninth nerve where this turns round the occipital artery, or, some-
times, higher up. It passes downwards on the surface of the sheath of
the carotid vessels, gradually crossing from the outer to the inner side,
gives a branch to the anterior belly of the omo hyoid muscle, and joins
about the middle of the neck in a loop with one or two branches from
the second and third cervical nerves, forming the ansa hypoylossi. The
concavity of this loop is turned upwards ; and the connection between
the nerves is effected by means of two or more interlacing filaments, which
HYPOGLOSSAL NERVE.
627
enclose an irregularly shiped space. From this interlacement of the nerves,
filaments are continued backwards to the posterior belly of the omo-hyoid,
and downwards to the sterno-hyoid and stern o- thyroid muscles. Occasionally
a filament is continued to the chest, where it joins the cardiac and phrenic
nerves.
Fig 419
Fig. 419. — VIEW OF THE DISTRIBUTION OP THK SPINAL ACCESSORY AND HrpoaiossAi,
NERVES (from Sappey after Hirschfeld and Leveille). ^
1, lingual nerve ; 2, pneumo-gasiric nerve ; 3, superior laryngeal (represented too large) ;
4, external laryngeal branch ; 5, spinal accessory ; 6, second cervical ; 7, third ; 8,
fourth ; 9, origin of the phrenic nerve; 10, origin of the branch to the subclavius muscle ;
11, anterior thoracic nerves ; 12, hypoglossal nerve ; 13, its descending branch ; 14, com-
municating branch from the cervical nerves; 15, 16, 18, 19, descending branches from
the plexiform union of these nerves to the sterno-hyoid, sterno-thyroid, and omo-hyoid
muscles ; 17, branch from the descendens noni to the upper belly of the omo-hyoid
muscle ; 20, branch from the hypoglossal nerve to the tbyro-hyoid muscle ; 21, communi-
cating twigs from the hypoglossal to the lingual nerve ; 22, terminal distribution of the
hypoglossal to the muscles of the tongue.
It is not uncommon to find the descending branch of the ninth nerve within the
sheath of the large cervical vessels, and in such cases it is placed either over or under
the vein. This nerve in some cases appears to be derived either altogether from the
pneumo-gastric, or from both the pneumo-gastric and hypoglossal nerves. There is
every reason, however, to believe that these varieties in origin are only apparent,
arising from the temporary adhesion of the filaments of this branch to those of the
628 THE CRANIAL NERVES.
pneumo-gastric. It is probable, moreover, that the descendens noni has little if any
real origin from the hypoglossal nerve : Luschka states it as the result of numerous
researches on the human subject that the descendens noni usually contains no fila-
ments from the hypoglossal, but is a branch from the first and second cervical, tem-
porarily associated with the ninth nerve ; and this quite agrees with the circumstance
that in the domestic animals the branches supplied to those muscles to which the
descendens noni of the human subject is distributed come from the cervical plexus.
Branches to muscles and the tongue. — The branch to the thyro-hyoid
muscle is a separate twig given off from the hypoglossal nerve as it
approaches the hyoid bone. The nerve supplies branches to the stylo -hyoid,
hyo-glossus, genio-byoid, and genio-hyo-gloasus muscles as it becomes
contiguous to each, and, when arrived close to the middle of the tongue
with the ranine artery, gives off several long slender branches, which pass
upwards into the substance of the organ. Some filaments join with others
proceeding from the gustatory nerve.
A branch is described as uniting with its fellow of the opposite side, in the sub-
stance of the genio-hyoid muscle, or between it and the genio-glossus. This loop, as
also the ansa hypoglossi, is recommended by Hyrtl as a particularly favourable
example for the observation of nerve-fibres returning to the nervous centres without
distribution, to which he gives the name of " nerves without ends." (" Nat. Hist.
Review," Jan. 1862.) That in the ansa hypoglossi an interchange of fibres takes
place, so that a filament of the spinal nerve is directed upwards along the branch of
the hypoglossal, and vice versa, was noticed by Cruveilhier.
Summary. — The hypoglossal nerve supplies, either alone or in union
with branches of the spinal nerves, all the muscles connected with the
os hyoides, including those of the tongue, with the exception of the digastric
and stylo-hyoid, the mylo-hyoid, and the middle constrictor of the pharynx.
It also supplies the sterno -thyroid muscle.
It is connected with the following nerves, viz., pneumo-gastrie, gustatory,
three upper cervical nerves, and the sympathetic.
B. SPINAL NERVES.
The spinal nerves are characterised by their origin from the spinal cord,
and their direct transmission outwards from the spinal canal in the intervals
between the vertebrae. Taken together, these nerves consist of thirty-one
pairs ; and, according to the region in which they issue from the spinal
canal, they are named cervical, dorsal, lumbar, sacral, and coccygeal.
By universal usage each pair of nerves in the dorsal, lumbar, and sacral
regions is named in correspondence with the vertebra beneath which it
emerges. There are thus left eight pairs of nerves between the cranium
and the first dorsal nerve, the first being placed above the atlas and the
eighth below the seventh cervical vertebra, which are reckoned by the
majority of writers as eight cervical nerves. The nerves of the thirty-first
pair emerge from the lower end of the sacral canal, below the first vertebra
of the coccyx, and are named coccygeal.
Although the plan of counting eight cervical nerves is continued in this work for
the sake of convenience, it being that which is most frequently followed, it is by no
means intended to represent this method as scientifically correct. The plan of
\Villis, who reckoned the suboccipital as a cranial nerve, had at least the advantage
that it made the numbers of the remaining seven cervical nerves correspond each
with the vertebra beneath which it emerged, as do the dorsal, lumbar and sacral
nerves; and if the suboccipital nerve, while recognised as the first spinal nerve, be
TEE SPINAL NERVES.— ROOTS.
kept distinct from the seven which succeed,
as is taught in some schools, a nomenclature
is arrived at much less objectionable than that
which is most prevalent. A reference, however,
to development (p. 17) will remind the reader
that in the primordial vertebrae each spinal
nerve is originally situated above the rib and
transverse process belonging to the same seg-
ment; and it will become apparent that the
scientifically accurate nomenclature of nerves
might be rather to name each in accordance
with the number of the vertebra below it. Thus
the eighth cervical nerve would be called first
dorsal, and so on.
Fig. 420. — DIAGRAMMATIC OUTLINE OF THE ROOTS
AND FIRST PART OF THE SPINAL NERVES,
TOGETHER WI1H THE SYMPATHETIC CORD OF
ONE SIDE. ^
The view is taken from before. In the upper
part of the figure the pons Varolii and medulla
oblongata are represented, and from V, to IX,
the roots of the several cranial nerves from the
trifacial to the hypoglossal are indicated. On
the left side C 1, is placed opposite the first cer-
vical or suboccipital nerve ; and the numbers 2 to
8 following below indicate the corresponding cer-
vical nerves; Br, indicates the brachial plexus ;
D 1, is placed opposite the intercostal part of the
first dorsal nerve, and the numbers 2 to 12 follow-
ing mark the corresponding dorsal nerves ; S 1,
the first lumbar nerve, and the numbers 2 to 5
following the remaining lumbar nerves; Cr, the
anterior crural, and o, the obturator nerve ; SI,
the first sacral, and the following numbers 2 to 5,
the remaining sacral nerves ; 6, the coccygeal
nerve; Sc, the great sciatic nerve; +, +, the
filum terrainale of the cord.
On the right side of the figure the following
letters indicate parts of the sympathetic nerves ;
viz., a, the superior cervical ganglion, com-
municating with the upper cervical spinal nerves
and continued below in the great sympathetic
cord ; b, the middle cervical ganglion ; c, d, the
lower cervical ganglion united with the first
dorsal ; d', the eleventh dorsal ganglion ; from
the fifth to the ninth dorsal ganglia the origins
of the great splanchnic nerve are shown ; I, the
lowest dorsal or upper lumbar ganglion ; ss, the
upper sacral ganglion. In the whole extent of the
sympathetic cord, the twigs of union with the
spinal nerves are shown.
Br
Sometimes an additional coccygeal nerve
exists. Among seven cases which appear to
have been examined with great care, Professor
Schlemm (" Observat. Neurolagicee,'' Berolini,
1834) found two coccygeal nerves on each side
in one instance, and on one side in another
case. In all the rest there was only a single
coccygeal nerve on each side.
Icr
Sc
630
THE SPINAL NERVES.
THE ROOTS OF THE SPINAL NERVES.
Each spinal nerve springs from the spinal cord by two roots which
approach one another, and, as they quit the spinal canal, join in the
corresponding intervertebral foramen into a single cord ; and each cord so
formed separates immediately into two divisions one of which is destined
for parts in front of the spine, the other for parts behind it.
The posterior roots of the nerves are distinguished from the anterior roots
by their greater size, as well as by the greater thickness of the fasciculi of
which they are composed. Each spinal nerve is furnished with a ganglion ;
but the first cervical or sub-occipital nerve is in some cases without one.
The size of the ganglia is in proportion to that of the nerves on which they
are formed.
The ganglia are in general placed in the intervertebral foramina, imme-
diately beyond the points at which the roots perforate the dura mater lining
the spinal canal. The first and second cervical nerves, however, which
leave the spinal canal, over the laminae of the vertebrae, have their ganglia
opposite those parts. The ganglia of the sacral nerves are contained in the
spinal canal, that of the last nerve being occasionally at some distance from
the point at which the nerve issues. The ganglion of the coccygeal nerve
is placed within the canal in the sac of dura mater, and at a variable dis-
tance from the origin of the nerve.
Fig. 421. Fig. 421.— DIFFERKS-T
VIEWS OF A PORTION OP
THE SPINAL CORD FROM
THK CERVICAL REGION
WITH THE ROOTS OF
THE NERVES. Slightly
enlarged.
In A, the anterior sur-
face of the specimen is
shown, the anterior nerve-
root of the right side
being divided ; in I>, a
view of the right side is
given ; in C, tho upper
surface is shown ; in D,
the nerve-roots and gan-
glion are shown from
below. 1, the anterior
median fissure ; 2, pos-
terior median fissure ; 3,
anterior lateral depres-
sion, over which thu ante-
rior nerve-roots are seen
to spread ; 4, posterior
lateral groove, into which
the posterior roots are
seen to sink ; 5, anterior
roots passing the ganglion ;
5', in A, the anterior root
divided ; 6, the posterior roots, the fibres of which enter the ganglion, 6' ; 7, the uciled
or compound nerve ; 7', the posterior primary branch seen in A and D, to be derived in
part from the anterior and in part from the posterior root.
«
The fibres of the po: terior root of the nerve divide into two bundles as they
approach the ganglion, and the inner extremity of the oval-shaped ganglion
is sometimes bilobate, the lobes corresponding to the two bundles of fibres.
SIZE AND STRUCTURE.— MODE OF DIVISION. 631
These fibres in man and the mammalia appear to pass through the ganglion with-
out union with its cells. The cells are both unipolar and bipolar, but the fibres con-
nected with them all pass to the periphery (Kolliker), so that beyond the ganglion
the posterior root of the nerve has received an additional set of fibres besides those
which it contains before reaching the ganglion. In fishes, on the contrary, all the
fibres of the posterior root are connected with the opposite extremities of the bipolar
cells of the ganglion.
The anterior roots of the spinal nerves are, as will be inferred from what
has been already stated, the smaller of the two ; they are devoid of
ganglioiiic enlargement, and their fibres are collected into two bundles near
the intervertebral ganglion, as in the posterior root.
Size, — The roots of the upper cervical nerves are smaller than those of the
lower nerves, the first being much the smallest. The posterior roots of
these nerves exceed the anterior in size more than in the other spinal nerves,
and they are likewise composed of fasciculi which are considerably larger
than those of the anterior roots.
The roots of the dorsal nerves, exception being made of the first, which
resembles the lowest cervical nerves and is associated with the in in a part of
its distribution, are of small size, and vary but slightly, or not at all, from
the second to the last. The fasciculi of both roots are thinly strewed over
the spinal cord, and are slender, those of the posterior exceeding in thickness
tho^e of the anterior root in only a small degree.
The roots of the lower lumbar, and of the upper sacral nerves, are the
largest of all the spinal nerves ; those of the lowest sacral and the coccygeal
nerve are, on the other hand, the slenderest. All these nerves are crowded
together round the lower end of the corJ. Of these nerves the anterior
roots are the smaller, but the disproportion between the anterior and pos-
terior roots is not so great as in the cervical nerves.
Length of the nerves in the spinal canal. — The place at which the roots
of the upper cervical nerves are connected with the spinal cord being nearly
opposite the foramina by which they respectively leave the canal, these roots
are comparatively short. But the distance between the two points referred
to is gradually augmented from nerve to nerve downwards, so that the
place of origin of the lower cervical nerves is the breadth of at least one
vertebra, and that of the lower dorsal nerves about the breadth of two
vertebrae above the foramina by which they respectively emerge from the
canal. Moreover, as the spinal cord extends no farther than the first
lumbar vertebra, the length of the roots of the lumbar, sacral, and coccygeal
nerves increases rapidly from nerve to nerve, ami in each case may be
estimated by the distance of the foramen of exit from the extremity of the
cord. Owing to their length, and the appearance they present in connection
with the spinal cord, the aggregation of the roots of the nerves last referred
to has been named the " cauda equina."
The direction the roots take within the canal requires brief notice. The
first cervical nerve is directed horizontally outwards. The roots of the
lower cervical and dorsal nerves at first descend over the spinal cord, held
in contact with it by the arachnoid, till they arrive opposite the several
iutervertebral foramina, where they are directed horizontally outwards.
The nerves of the cauda equina run in the direction of the spinal canal.
Division of the nerves. — The two roots of each of the spinal nerves unite
immediately beyond the ginglion, and the trunk thus formed separates,
as already mentioned, into two divisions, an anterior and a posterior, which
are called primary branches or divisions.
In the detailed description of the spinal nerves which follows, we shall
632 THE SPINAL NERVES.
begin with their posterior primary divisions, calling attention first to certain
characters common to the whole of them, and afterwards stating separately
the arrangement peculiar to each group of nerves (cervical, dorsal, &c.)
POSTERIOR PRIMARY DIVISIONS
OF THE SPINAL NERVES.
The posterior divisions of the spinal nerves are, with few exceptions,
smaller than those given to the fore part of the body. Springing from the
trunk which results from the union of the roots of the nerve in the inter-
vertebral foramen, or frequently by separate fasciculi from each of the
roots, each turns backwards at once, and soon divides into two parts, distin-
guished as external and internal, distributed to the muscles and the integu-
ment behind the spine. The first cervical, the fourth aud fifth sacral and
the coccygeal nerve are the only nerves the posterior divisions of which do
not separate into external and internal branches.
THE SUBOCCIPITAL NERVE. — The posterior division of the suboccipital
nerve, which is the larger of the two primary divisions, emerging over the
arch of the atlas, between this and the vertebral artery, enters the space
bounded by the larger rectus and the two oblique muscles, and divides
into branches for the surrounding muscles.
a. One branch descends to the lower oblique muscle and gives a filament, through
or over the fibres of that muscle, to join the second cervical nerve.
6. Another ascends over the larger rectus muscle, supplying it and the smaller
rectus.
c. A third enters the upper oblique muscle.
d. A fourth sinks into the complexus, where that muscle covers the nerve and its
branches.
A cutaneous branch is occasionally given to the back of the head ; it accompanies
the occipital artery, and is connected beneath the integument with the great and
small occipital nerves.
Fig. 422. — SUPERFICIAL AND DEEP DISTRIBUTION OP THE POSTERIOR PRIMARY DIVISIONS
OF THE SPINAL NERVES (from Hirschfeld and Leveille). £
On the left side the cutaneous branches are represented as lying upon the superficial
layer of muscles ; on the right side, the superficial muscles having been removed, the
splenius and complexus have been divided in the neck, and the erector spinae separated
and partially removed in the back, so as to expose the deep issue of the nerves.
«, a, lesser occipital nerve from the cervical plexus ; 1, external muscular branches of
the first cervical nerve and union by a loop with the second ; 2, placed on the rectus
capitis posticus major, marks the great occipital nerve passing round the short muscles
and piercing the complexus : the external branch is seen to the outside ; 2', cranial dis-
tribution of the great occipital ; 3, external branch of the posterior primary division of
the third nerve ; 3', its internal branch, or third occipital nerve ; 4', 5', 6', 7', 8',
internal branches of the several corresponding nerves on the left side : the external
branches of these nerves proceeding to muscles are displayed on the right side : dl, io
d 6, and thence to c? 12, external muscular branches of the posterior primary divisions of
the twelve dorsal nerves on the right side ; d 1', to d 6', the internal cutaneous branches
of the six upper dorsal nerves on the left side ; d 7', to d 12', cutaneous branches of the
six lower dorsal nerves from the external branches ; Z, I, external branches of the pos-
terior primary branches of several lumbar nerves on the right side piercing the muscles,
the lower descending over the gluteai region ; I', l\ the same more superficially on the left
side ; s, s, on the right side, the issue and union by loops of the posterior primary divisions
of four sacral nerves ; s't s', some of these distributed to the skin on the left side.
POSTERIOR PRIMARY DIVISIONS.
633
Fig. 422.
CERVICAL NERVES, with the exception of the saboccipital. — The external
branches give only muscular offsets, and are distributed to the splenius and
the blender muscles prolonged to the neck from the erector spinse, viz., the
634 THE SPINAL NERVES.
cervicalis ascendens, and the trans versa! is colli with the trachelo-mastoid.
That of the second nerve is the largest of the series of external branches,
and is often united to the corresponding branch of the third ; it supplies
the complexus muscle which covers it, and ends in the splenius and trachelo-
inastoid muscles.
The internal branches, larger than the external, are differently disposed at
the upper and the lower parts of the neck. That of the second cervical
nerve is named, from its size and destination, the great occipital, and
requires separate notice. The rest are directed inwards to the spinous pro-
cesses of the vertebrae. Those derived from the third, fourth, and fifth
nerves pass over the semispinalis and beneath the complexus muscle, and,
having reached the spines of the vertebrae, turn transversely outwards and
are distributed in the integument over the trapezius muscle. From the
cutaneous branch of the third nerve a branch passes upwards to the integu-
ment on the lower part of the occiput, lying at the inner side of the great
occipital nerve, and is sometimes called third occipital nerve.
Between the inner branches of the first three cervical nerves, beneath the complexus,
there are frequently communicating fasciculi ; and this communication Cruveilhier
has designated as " the posterior cervical plexus."
The internal branches from the lowest three cervical nerves are placed
beneath the semispinalis muscle, and end in the muscular structure, without
furnishing (except occasionally the sixth) any offset to the skin. These
three nerves are the smallest of the series.
The great occipital nerve is directed upwards on the lower oblique muscle,
and is transmitted to the surface through the complexus and trapezius
muscles, giving twigs to the complexus. Ascending with the occipital
artery, it divides into branches, which radiate over the occipital part of the
occipito-frontalis muscle, some appearing to enter the muscle, and others
joining the smaller occipital nerve.
An auricular branch is sometimes supplied to the back of the ear by the great
occipital nerve.
DORSAL NERVES. — The external branches increase in size from above
downwards. They are directed through or beneath the longissiinus dorsi to
the space between that muscle and the ilio-costalis and accessory ; they supply
both those muscles, together with the small muscles continued upwards from
the erector spinse to the neck, and also the levatores costarum. The lower
five or six nerves give cutaneous twigs, which are transmitted to the integu-
ment in a line with the angles of the ribs.
The internal branches of the upper six dorsal nerves appear in the interval
between the multifidus spinee and the semispinalis dorsi ; they supply
those muscles, and become cutaneous by the side of the spinous processes of
the vertebras. The cutaneous branch from the second nerve, and sometimes
others, reach as far as the scapula. The internal branches of the lower six
dorsal nerves are placed between the multifidus spinso and longissimus dorsi,
and end in the multifidus without giving branches to the integument.
Where cutaneous nerves are supplied by the internal branches, there are
none from the external branches of the same nerve, and vice versa.
LUMBAR NERVES. — The external branches enter the erector spinse, and
give filaments to the intertrans verse muscles. From the upper three,
cutaneous nerves are supplied ; and from the last, a fasciculus descends to
the corresponding branch of the first sacral nerve. The cutaneous nerves
given from the external branches of the first three lumbar nerves, pierce the
ANTERIOR PRIMARY DIVISIONS. 635
fleshy part of the ilio-costalis, and the apcmeurosis of the latissimus dorsi ;
they cross the iliac crest near the edge of the erector spinse, and terminate
in the integument of the gluteal region. One or more of the filaments may
be traced as far as the great trochanter of the femur.
The internal branches wind backwards in grooves close to the articular
processes of the vertebrae, and sink into the mukifidus spinse muscle.
SACRAL NERVES. — The posterior divisions of the nerves, except the
last, issue from the sacrum through its posterior foramina. The first three
are covered at their exit from the bone by the multifidus spinre muscle,
and bifurcate like the posterior trunks of the other spinal nerves ; but
the remaining two, which continue below that muscle, have a peculiar
arrangement, and require separate examination.
The internal branches of the Jirst three sacral nerves are small, and are
lost in the multifidus spinse muscle.
The external branches of the same nerves are united with one another,
and with the last lumbar and fourth sacral nerves, so as to form a series of
anastomotic loops on the upper part of the sacrum. These branches are
then directed outwards to the cutaneous or posterior surface of the great
sacro-sciatic ligament, where, covered by the gluteus maximus muscle, they
form a second series of loops, and end in cutaneous nerves. These pierce the
great gluteus muscle in the direction of a line from the posterior iliac spine
to the tip of the coccyx. They are commonly three in number — one is
near the innominate bone, another opposite the extremity of the sacrum,
and the third about midway between the other two. All are directed out-
wards over the great gluteal muscle.
In six dissections by Ellis tliis arrangement was found to be the most frequent.
The variations to which it is liable are these : — the first nerve may not take part in
the second series of loops, and the fourth may be associated with them.
The posterior divisions of the last two sacral nerves are smaller than those
above them, and are not divided into external and internal branches. They
are connected with each other by a loop on the back of the sacrum, and the
lowest is joined in a similar manner with the coccygeal nerve ; one or two
small filaments from these sacral nerves are distributed behind the coccyx.
COCCYGEAL NERVE. — The posterior division of the coccygeal nerve is very
small, and separates from the anterior primary portion of the nerve in the
sacral canal. It is joined by a communicating filament from the last sacral
nerve, and ends in the fibrous structure covering the posterior surface of the
coccyx.
ANTERIOR PRIMARY DIVISIONS
OP THE SPINAL NERVES.
The anterior primary divisions of the spinal nerves are distributed to the
parts of the body situated in front of the vertebral column, including the
limbs. They are, for the most part, ponsiderably larger than the posterior
divisions.
The anterior division of each spinal nerve is connected by one or two
slender filaments with the sympathetic. Those of the cervical, lumbar, and
sacral nerves form plexuses of various forms ; but those of the dorsal nerves
remain for the most part separate one from another.
T T 2
636 THE CERVICAL NERVES AND PLEXUS.
CERVICAL NERVES.
The anterior divisions of the four upper cervical nerves form the cervical
plexus. They appear at the side of the neck between the scalenus medius
and rectus anticus major muscles. They are each connected by a commu-
nicating filament with the first cervical ganglion of the sympathetic nerve,
or with the cord connecting that ganglion with the second.
The anterior divisions of the four lower cervical nerves, larger than those
of the upper four, appear between the scaleni muscles, and, together with
that of the first dorsal, go to form the brachial plexus. They are each
connected by a filament with one of the two lower cervical ganglia of the
sympathetic, or with the plexus on the vertebral artery.
The anterior divisions of the first and second nerves require a notice
separately from the description of the nerves of the cervical plexus.
SUBOCCIPITAL NERVE.
The anterior primary division of the first nerve runs forwards in a groove
on the atlas, and bends downwards in front of the transverse process of that
vertebra to join the second nerve. In this course forwards it lies beneath
the vertebral artery, and at the inner side of the rectus lateralis muscle, to
which it gives a branch. As it crosses the foramen in the transverse process
of the atlas, the nerve is joined by a filament from the sympathetic ; and
from the arch, or loop of the atlas, which it makes in front of the transverse
process, branches are supplied to the two anterior recti muscles. Short
filaments connect this part of the nerve with the pneumo-gastric, the hypo-
glossal, and the sympathetic nerves.
Valentin notices filaments distributed to the articulation of the occipital bone with
the atlas, and to the mastoid process of the temporal bone. ,
SECOND CERVICAL NERVE.
The anterior division of the second cervical nerve, beginning between the
arches of the first two vertebrae, is directed forwards between their trans-
verse processes, being placed outside the vertebral artery, and beneath the
iutertransverse and other muscles fixed to those processes. In front of the
intertransverse muscles the nerve divides into an ascending part, which
joins the first cervical nerve, and a descending part to the third.
•V .
CERVICAL PLEXUS.
The cervical plexus is formed by the anterior divisions of the first four
cervical nerves, and distributes branches to some of the muscles of the neck,
and to a portion of the integument of the head and neck. It is placed
opposite the first four vertebras, beneath the sterno-mastoid muscle, and rests
against the middle scalenus muscle and the levator auguli scapuhe. The
disposition of the nerves in the plexus is easily recognised. Each nerve
except the first, branches into au ascending and a descending part : and
these are united in communicating loojps with the contiguous nerves. From
the union of the second and third nerves, superficial branches are supplied
to the head and neck ; and from the junction of the third with the fourth,
arise the cutaneous nerves of the shoulder and chest. Muscular and com-
municating branches spring from the same nerves.
The branches of the plexus may be separated into two sets — a superficial
THE CERVICAL PLEXUS.
637
and deep ; the superficial consisting of those which ramify over the cervical
fascia, supplying the integument and some also the platysma ; the deep
comprising branches which are distributed for the most part to the muscles.
The superficial nerves may be subdivided into ascending and descending ;
the deep nerves into an internal and external series.
Fig. 423. — DIAGRAMMATIC Fig 423.
OUTLINE OP THE FIRST
PARTS OP THE CERVICAL
AND UPPER DORSAL
NERVES, SHOWING THE
CERVICAL AND BRACHIAL
PLEXUSES. J
The nerves are separated
from tlie spinal cord at
their origin and are sup-
posed to be viewed from
before. Cl, is placed op-
posite the roots of the first
cervical or suboccipital
nerve, and the roman num-
bers in succession from IF,
to VIII, opposite the roots
of the corresponding cer-
vical nerves ; DI, is placed
opposite to the roots of the
first dorsal nerve, and II,
and IK, opposite the second
and third nerves ; the origin
of the posterior primary
branch is shown in all the
nerves; of these p 2, indi-
cates the great occipital
from the second, and ^;3,
the smallest occipital nerve
from the third. In con-
nection with the cervical
plexus the following indica-
tions are given ; 1, anterior
primary branch of the
first cervical nerve and loop
of union with the second
nerve ; 2, lesser occipital
nerve proceeding in this
case from the second cervi-
cal nerve, more frequently
from the second and third ;
3, great auricular nerve
from the second and third ;
3', superficial cervical nerve from the third; 3 n, communicating branches to the descen-
dens noni from the second and third ; 3 s, communicating to the spinal-accessory from the
second, third, and fourth ; 4, supraclavicular and supraacromial descending nerves :
the loops or arches of communication between the four upper cervical nerves, and between
the fourth and fifth are shown ; 4', the phrenic nerve springing from the fourth and fifth
nerves. In connection with the nerves of the brachial plexus and the remaining nerves
the following indications are given — V, to VIII7, and D', the five roots of the brachial
plexus ; 5, the rhomboid nerve ; 5', suprascapular ; 5", posterior thoracic ; 6, nerve to the
subclavius muscle; 7, 7, inner and outer anterior thoracic nerves; 8, 8', 8", upper and
lower subscapular nerves. In the larger nerves proceeding to the shoulder and arm from
the plexus, those of the anterior division are represented of a lighter shade, those belonging
to the posterior division darker ; ec, external cutaneous or musculo-cutaneous ; ?/i, median;
M, ulnar, ic, internal cutaneous ; w, nerve of Wrisberg ; r, musculo -spiral ; c, circum-
flex ; i, intercostal nerves ; i', lateral branch of the same ; ih, intercosto-humeral nerves.
Ill
038 THE CERVICAL NERVES AND PLEXUS.
I. SUPERFICIAL ASCENDING BRANCHES.
SUPERFICIAL CERVICAL NERVE.
This nerve takes origin from the second and third cervical nerves, turns
forward over the sterno-mastoid about the middle, and, after perforating the
cervical fascia, divides beneath the platysma myoides into two branches,
which are distributed to the anterior and lateral parts of the neck.
a. The upper branch gives an ascending twig which accompanies the external jugular
vein, and communicates freely with the facial nerve (cervico-facial division) ; it is then
transmitted through the platysma to the surface, supplying that muscle, and ramifies
in the integument of the upper half of the neck on the fore part, filaments reaching as
high as the lower maxilla.
b. The lower branch likewise pierces the platysma, and is distributed below the
preceding, its filaments extending in front as low as the sternum.
The superficial cervical nerve may arise from the plexus in the form of two or more
distinct branches. Thus Valentin describes three superficial cervical nerves, which he
names superior, middle, and inferior. (" Sommerring v. Bau," &c.)
While the superficial cervical nerve ramifies over the platysma myoides, the facial
nerve is beneath the muscle. According to Valentin many anastomotic arches are
formed on the side of the neck between those two nerves, as well as between the
branches of the former, one with another.
GREAT AURICULAR NERVE.
This nerve winds round the outer border of the sterno-mastoid, and is
directed obliquely upwards beneath the platysma myoides, between the
muscle and the deep fascia of the neck, to the lobe of the ear. Here the
nerve gives a few small branches to the face, and ends in the auricular
and mastoid branches.
a. The auricular branches are directed to the back of the external ear, on which
they ramify, and are connected with twigs derived from the facial nerve. One
of these branches reaches the outer surface of the ear by a fissure between the
antihelix and the concha. A few filaments are supplied likewise to the outer part
of the lobule.
b. The mastoid branch is united to the posterior auricular branch of the facial
nerve, and ascends over the mastoid process to the integument behind the ear.
c. The facial branches of the great auricular nerve, which extend to the integu-
ments of the face, are distributed over the parotid gland. Some slender filaments
penetrate deeply through the substance of the gland, and communicate with the facial
nerve.
SMALL OCCIPITAL NERVE.
The smaller occipital nerve varies in size, and is sometimes double. It
springs from the second cervical nerve, and is directed almost vertically to
the head along the posterior border of the sterno-mastoid muscle. Having
perforated the deep fascia near the cranium, the small occipital nerve is
continued upwards between the ear and the great occipital nerve, and ends
in cutaneous filaments which extend upwards in the scalp ; it communicates
with branches from the larger occipital nerve, as well as with the posterior
auricular branch of the facial. It appears to supply sometimes the occipito-
frontalis muscle.
The auricular branch (ram. auricularis superior posterior) is distributed to the
upper part of the ear on the posterior aspect, and to the elevator muscle of the auricle.
This auricular branch is an offset from the great occipital nerve, when the small
occipital is of less size than usual.
STJPRACLAVICULAR NERVES. 639
II. SUPERFICIAL DESCENDING BRANCHES.
SUPRACLAVICULAR NERVES.
The descending series of the superficial nerves are thus named. There
Fig. 424.
Fig. 424. — VIEW OP THE SUPERFICIAL DISTRIBUTION OF THE NERVES PROCEEDING FROM
TEE CERVICAL PLEXUS (from Sappey after Hirschfeld and Leveille). £
1, superficial cervical nerve; 2,2, descending branches of the same; 3, ascending
branches ; 4, twigs uniting with the facial ; 5, great auricular nerve ; 6, its parotid
branch ; 7, its external auricular branch ; 8, twig of the same which pierces the auricle
to pass to its outer surface ; 9, branch to the deep surface of the pinna ; 10, its union
with the posterior auricular of the facial nerve ; 11, small occipital nerve ; 12, its branch
which unites with the great occipital nerve ; 13, a mastoid branch or second small occipital ;
14, twigs from this to the back of the neck ; 15, 16, supraclavicular nerves; 17, 18,
supraacromial nerves ; 19, branch of the cervical nerves passing into the trapezius muscle ;
20, spinal accessory distributed to the same and receiving a uniting branch from the cervical
nerves ; 21, branch to the levator scapuli ; 22, trunk of the facial nerve ; 23, its posterior
auricular branch passing into the occipital and posterior and superior auricular muscles ;
24, its cervico- facial branches.
640 THE CERVICAL NERVES AND PLEXUS.
are two of these nerves, or, in some cases, a greater number. They arise
from the third and fourth cervical nerves, and descend in the interval
between the sterno-mastoid and the trapezius muscles. As they approach
the clavicle, the nerves are augmented to three or more iii number, and are
recognised as internal, middle, and posterior.
a. The internal (sternal) branch, which is much smaller than the rest, ramifies over
the inner half of the clavicle, and terminates near the sternum.
b. The middle branch, lying opposite the interval between the pectoral and deltoid
muscles, distributes some twigs over the fore part of the deltoid, and others over
the pectoral muscle. The latter join the small cutaneous branches of the intercostal
nerves.
c. The external or posterior branch (acromial) is directed outwards over the acro-
mion, and the clavicular attachment of the trapezius muscle, and ends in the integu-
ment of the outer and back part of the shoulder.
III. DEEP BRANCHES : INNER SERIES.
CONNECTING BRANCHES.
The cervical plexus is connected near the base of the skull with the
trunks of the pneumo-gastric, hypoglossal, and sympathetic nerves, by
means of filaments intervening between those nerves and the loop formed
by the first two cervical nerves in front of the atlas (p. 637).
MUSCULAR BRANCHES.
Branches to the anterior recti muscles proceed from the cervical nerves
close to the vertebrae, including the loop between the first two of these
nerves.
Two branches to the ansa hypoglossi, one from the second, the other from
the third cervical nerve, descend over or under the internal jugular vein, to
form a loop of communication with the rarnus descendens noni, and aid in
the supply of the muscles below the hyoid bone (p. 6 20).
PHRENIC NERVE.
The diaphragmatic or phrenic nerve passes down through the lower part
of the neck and the thorax to its destination.
It commences from the fourth cervical nerve, and receives usually a fasci-
culus from the fifth. As it descends in the neck, the nerve is inclined
inwards over the anterior scalenus muscle ; and near the chest it is joined
by a filament of the sympathetic, and sometimes also by another filament
derived from the fifth and sixth cervical nerves.
As it enters the thorax each phrenic nerve is placed between the sub-
clavian artery and vein, and crosses over the internal mammary artery near
the root. It then takes nearly a straight direction, in front of the root of
the lung on each side, and along the side of the pericardium, — between
this and the mediastinal part of the pleura. Near the diaphragm it divides
into branches, which separately penetrate the fibres of that muscle, and then
diverging from each other, are distributed on the under surface.
The right nerve is placed more deeply than the left, and is at first directed
along the outer side of the right innominate vein, and the descending vena
cava.
DEEP CERVICAL NERVES.- BRACIIIAL PLEXUS. 641
The nerve of the left side is a little longer than that of the right, in conse-
quence of the oblique position of the pericardium round which it winds,
and also because of the diaphragm beiug lower on this than on the opposite
side. This nerve crosses in front of the arch of the aorta and the pul-
monary artery before reaching the pericardium.
Besides the terminal branches supplied to the diaphragm, each phrenic nerve gives
filaments to the pleura and pericardium ; and receives sometimes an offset from the
union of the descendens noni with the cervical nerves. Swan notices this union as
occurring only on the left side. Luschka describes twigs from the lower part of the
nerve to the peritoneum, the inferior cava, and the right auricle of the heart.
One or two filaments of the nerve of the right side join in a small ganglion with
branches to the diaphragm which are derived from the solar plexus of the sympa-
thetic ; and from the ganglion twigs are given to the suprarenal capsule, the hepatic
plexus, and the lower vena cava. On the left side there is a junction between the
phrenic and the sympathetic nerves near the oesophageal and aortic openings in the
diaphragm, but without the appearance of a ganglion.
IV. DEEP BRANCHES : EXTERNAL SERIES.
Muscular branches. — The sterno-mastoid receives a branch from the
second cervical nerve. Two branches proceed from the third nerve to the
levator anguli scapulas ; and from the third and fourth cervical nerves, as
they leave the spinal canal, branches are given to the middle scalenus
muscle. Further, the trapezius has branches prolonged to it ; and thus,
like the sterno-mastoid, this muscle receives nerves from both the spinal
accessory and the cervical plexus.
Connection with the spinal accessory nerve. — In the substance of the sterno-
mastoid muscle, this nerve is connected with the branches of the cervical
plexus furnished to that muscle. It is also connected with the* branches
distributed to the trapezius — the union between the nerves being beneath
the muscle, and having the appearance of a plexus ; and with another
branch of the cervical plexus in the interval between the two muscles.
Summary of the cervical plexus. — From the cervical plexus are distributed
cutaneous nerves to the ba?k of the head, to part of the ear and face, to the
anterior half of the neck, and to the upper part of the trunk. The muscles
supplied with nerves from the plexus are the sterno-mastoid, the platysma,
and the lower hyoid muscles in part ; the anterior recti, the levator anguli
scapulse, the trapezius, the scalenus medius, and the diaphragm. By means
of its branches the plexus communicates with the pneumo-gastric, spinal
accessory, hypoglossal, and sympathetic nerves.
BRACHIAL PLEXUS.
This large plexus, from which the nerves of the upper limb are supplied,
is formed by the union of the anterior trunks of the four lower cervical and
first dorsal nerves ; and it further receives a fasciculus from the lowest of
the nerves (fourth), which goes to form the cervical plexus. The plexus
extends from the lower part of the neck to the axillary space, and termi-
nates opposite the coracoid process of the scapula in large nerves for the
supply of the limb.
The manner in which the nerves are disposed in the plexus is liable to
some variation, but the following may be regarded as the arrangement most
frequently met with. The fifth and sixth cervical are joined at the outer
border of the scalenus, and a little farther out receive the seventh nerve,
642
THE BEACHIAL PLEXUS.
— the three nerves giving rise to one large upper cord. The eighth cervical
and first dorsal nerves are united in another lower cord whilst they are
Fig. 425.
Fig. 425. — DEEP DISSECTION OF THE AXILLA, SHOWING THE BRACHIAL PLEXUS AND
NEIOHBOUKING NERVES (from Sappey after Hirschfeld and Leveille). £
The clavicle has been sawn through near its sternal end, and is turned aside with the
muscles attached to it ; the subclavius, and the greater and lesser pectoral muscles have
been removed from the front of the axilla. 1, loop of union between the descendens noni
and a branch of the cervical plexus ; 2, pneumo-gastric ; 3, phrenic passing down to the
inner side of the scalenus anticus muscle ; 4, anterior primary division of the fifth cervical
nerve ; 5, the same of the sixth ; 6, 7, the same of the seventh and eighth cervical nerves ;
8, the same of the first dorsal nerve ; 9, 9, branch from the plexus to the subclavius
muscle, communicating with the phrenic nerve; 10, posterior thoracic nerve distributed
to the serratus magnus ; 11, upper anterior thoracic nerve passing into the great pectoral
muscle ; 13, lower anterior thoracic distributed to the lesser pectoral ; 14, twig of com-
munication between these two nerves ; 12, suprascapular nerve passing through the supra-
scapular notch ; 15, lower of the two subscapular nerves ; 16, nerve of the teres major ;
17, long subscapular, or nerve of the latissimus dorsi ; 18, accessory of the internal
cutaneous nerve ; 19, union of the accessory cutaneous with the second and third inter-
costal nerves ; 20, lateral branch of the secoud intercostal ; 21, second internal cutaneous
or nerve of Wrisberg ; 22, internal cutaneous nerve ; 23, the ulnar nerve to the inside of
the axillary artery, passing behind the vein, and having, in this case, a union with the
upper division of the plexus ; 24, the median nerve immediately below the place where its
two roots embrace the artery, which is divided above this place; 25, the musculo-cutaneous
nerve passing into the coraco-brachialis muscle; 26, the musculo-spiral nerve passing
behind the divided brachial artery.
BRANCHES OF THE BRACHIAL PLEXUS.
643
between the scaleni muscles. The two cords thus formed lie side by side
in the fore part of the plexus, and external to the first part of the axillary
vessels.. At the same place, or lower down, a third intermediate or posterior
cord is produced by the union of fasciculi from each of the other two cords,
or separately from the nerves forming them. The three cords of which the
plexus now consists, are placed, one on the outer side of the axillary artery,
one on the inner side, and one behind that vessel, and are continued into
the principal nerves for the arm.
The two fasciculi which unite to form the intermediate of the three
trunks are generally separated at a higher level than the formation of the
two other trunks, but they are also frequently given off as low as the clavicle,
or even farther down ; this gives rise to some varieties, more apparent than
real. The seventh nerve also may give a branch to the cord below it.
The branches proceeding from the plexus are numerous, and may be
conveniently divided into two classes — viz., those that arise above the
clavicle, and those that take origin below the bone.
BRANCHES ABOVE THE CLAVICLE.
Above the clavicle there arise from the trunks of the brachial plexus, the
posterior thoracic and supra scapular nerves, a nerve for the rhomboid
muscles, another for the subclavius, irregular branches for the scaleni and
longus colli, and a branch to join the phrenic nerve.
The branches for the scaleni and longus colli muscles spring in an irregular manner
from the lower cervical nerves close to their place of emergence from the vertebral
foramina.
The branch for the rhomboid muscles arises from the fifth nerve, and is directed
backwards to the base of the scapula through the fibres of the middle scalenus and
beneath the levator anguli scapulae. It is distributed to the deep surface of the
rhomboid muscles, and gives sometimes a branch to the levator scapulae.
Fig. 426. — DISTRIBUTION OP
TOE SUPRASCAPULAR AND
CIRCUMFLEX NERVES (from
HirschfeldandLeveille). |
Fig. 426.
1'
a, the scalenus medius and
posticus muscles ; b, levator
anguli scapulae ; c, acromion ;
d. deltoid muscle, of which
the back part has been de-
tached from the scapula and
in part removed ; e, rhomboid
muscle ; /, teres major ; g, la-
tissimus dorsi ; 1 , the brachial
plexus of nerves as seen from
behind ; 1', the nerve of the
levator scapulae and rhomboid
muscles ; 2, placed on the
clavicle, marks the supra-
scapular nerve ; 3, its branch
to the supraspinatus muscle ;
4, branch to the infraspinatus ;
5, placed on the back of the
humerus below the insertion
of the teres minor, marks the circumflex nerve passing out of the quadrangular interval ;
6, its branch to the teres minor muscle ; 7, branches to the deep surface of the deltoid ;
8, cutaneous branch to the back of the shoulder.
644
THE BRACHIAL PLEXUS.
The nerve of the subdavius muscle, of small size, arises from the front of the cord
which results from the union of the fifth and sixth cervical nerves. It is directed
over the outer part of the subclavian artery to the deep surface of the subclavius
muscle. This small nerve is commonly connected with the phrenic nerve in the neck
or in the che-st, by means of a slender filament.
Branch to join the phrenic nerve.— This small and short branch is an offset from
the fifth cervical nerve ; it joins the phrenic nerve on the anterior scalenus muscle.
POSTERIOR THORACIC NERVE.
The posterior thoracic nerve (nerve of the serratus magnus, external
respiratory of Bell) is formed in the substance of the middle scalenus muscle
by two roots, one from, the fifth and another from the sixth nerve, and reaches
the surface of the scalenus lower than the nerve of the rhomboid muscles,
with which it is often connected. It descends behind the brachial plexus
on the outer surface of the serratus magnus, nearly to the lower border of
that muscle, supplying it with numerous branches.
SUPRASCAPULAR NERVE.
The suprascapular nerve arises from the back of the cord formed by the
union of the fifth and sixth nerves, and bends beneath the trapezius to the
upper border of the scapula, where it passes between the muscles and the
bone. Entering the supraspinous fossa of the scapula, through, the supra-
scapular notch (beneath the ligament which crosses the notch), the supra-
scapular nerve supplies two branches to the supraspinatus, one near the
upper, the other near the lower part of the muscle ; and it then descends
through the great scapular notch into the lower fossa, where it ends in the
infraspinatus muscle.
In the upper fossa of the scapula, a slender articular filament is given to the
shoulder-joint, and in the lower fossa other twigs of the nerve enter the same joint
and the substance of the scapula.
BRANCHES BELOW THE CLAVICLE.
Origin of nerves from the plexus. — The several nerves now to be described
are derived from the three great cords of the plexus in the following order.
From the upper or outer cord, — the external of the two anterior thoracic
nerves, the musculo-cutaneous, and the outer root of the median.
From the lower or inner cord, — the inner of the two anterior thoracic, the
nerve of Wrisberg, the internal cutaneous, the ulnar, and the inner root of
the median.
From the posterior cord, — the subscapular nerves, the circumflex, and
the musculo-spiral.
The nerves traced to the spinal nerves. — If the fasciculi of which the principal
nerves are composed be followed through the plexus, they may be traced to those of
the spinal nerves which in the subjoined table are named along with each trunk.
The higher numbers refer to the cervical nerves, the unit to the dorsal nerve : —
5.6.7.8.
Subscapular from
Circumflex . •
Musculo-spiral .
External cutaneous .
Median 5.6.7.8.1.
1. or 7.8.1.
Ulnar
Internal cutaneous . )
Small internal cutaneous )
outer 5.6.7
inner 8.1.
Anterior thoracic
The outline in Fig. 423, taken from a dissection, represents one of the most
common arrangements.
ANTERIOR THORACIC.— SUBSCAPULAR NERVES.
645
Some differences will be found in the statements of anatomists who have
investigated the subject— for instance, Scarpa (" Annotations Anatom.")and Kronen-
berg (" Plex. nervor. Structura et Virtutes ") — with respect to the nerves to which
the branches are assigned. This difference is mainly owing to the variation which
actually exists in different cases.
ANTERIOR THORACIC NERVES.
The anterior thoracic nerves, two in number, supply the pectoral
muscles.
The external, or more superficial branch, arising from the outer cord,
crosses inwards over the axillary artery, and terminates in the great pectoral
muscle.
The internal, or deeper branch, springing from the inner cord, comes
forwards between the axillary artery and vein to the small pectoral muscle,
and is joined by a branch from the exterual. This nerve presents a plexi-
form division beneath the small pectoral muscle, and supplies branches to
it and the larger pectoral muscle. The two nerves are connected by a tila-
ment which forms a loop over the artery at the inner side.
SUBSCAPULAR NERVES.
These nerves, three in number, take origin from
the posterior cord of the plexus.
The upper nerve, the smallest of the sub-
scapular nerves, penetrates the upper part of the
subscapular muscle. The lower nerve gives a
branch to the subscapularis at its axillary border,
and ends in the teres major muscle. There is
sometimes a distinct nerve for the last-named
muscle.
The long subscapular nerve, the largest of the
three, runs along the lower border of the sub-
scapular muscle to the lutissinius dorsi, to which
it is distributed.
Fig. 427. — DISTRIBUTION OF THE POSTKRIOR CUTANEOUS
NERVES OP THE SHOULDER AND ARM (from Hirschfeld
and Leveille). I
1, supra-acromial branches of the cervical nerves de-
scending on the deltoid muscle ; 2, ascending or reflected,
and 2', descending cutaneous branches of the circumflex
nerve ; 3, inferior external cutaneous of the musculo-spiral
nerve ; 4, external and posterior cutaneous branches of the
niusculo-cutaneous nerve to the forearm ; 5, internal
cutaneous of the musculo-spiral ; 6, intercosto-humeral
branches ; 7, twigs of the nerve of Wrisberg ; 8, upper
posterior branch of the internal cutaneous nerve ; 9, lower
branch of the same.
CIRCUMFLEX NERVE.
The circumflex or axillary nerve gives both
muscular and cutaneous nerves to the shoulder.
Springing from the posterior cord, this nerve is at
first placed behind the axillary artery, but at the
lower border of the subscapular muscle it is inclined backwards with the
posterior circumflex artery, in the space between the scapula and tere&
646 THE BRACHIAL PLEXUS.
major muscle above the long head of the triceps, and separates into an
upper and a lower branch, which are distributed to the deltoid and teres
minor muscles, the integument of the shoulder, and the shoulder-joint.
a. The upper portion winds round the upper part of the humerus, extending to the
anterior border of the deltoid muscle, to which it is distributed. One or two
cutaneous filaments, penetrating between the muscular fibres, are bent downwards
and supply the integument over the lower part of the muscle.
b. The lower branch supplies offsets to the back part of the deltoid, and furnishes
the nerve to the teres minor, which is remarkable in presenting a gangliform enlarge-
ment. It then turns round the posterior border of the deltoid below the middle, and
ramifies in the integument over the lower two-thirds of that muscle, one branch
extending to the integument over the long end of the triceps muscle.
c. An articular filament for the shoulder-joint arises near the commencement of
the nerve, and enters the capsular ligament below the subscapular muscle.
INTERNAL CUTANEOUS NERVE.
At its origin from the inner cord of the brachial plexus, this nerve is
placed on the inner side of the axillary artery. It becomes cutaneous about
the middle of the arm, and after perforating the fascia, or, in some cases,
before doing so, is divided into two parts ; one destined for the anterior,
the other for the posterior surface of the forearm.
a. The anterior branch crosses at the bend of the elbow behind (in some cases
over) the median basilic vein, and distributes filaments in front of the forearm, as
far as the wrist; one of these is, in some instances, joined with a cutaneous branch
of the ulnar nerve.
b. The posterior branch inclines obliquely downwards at the inner side of the basilic
vein, and winding to the back of the forearm, over the prominence of the internal
condyle of the humerus, extends somewhat below the middle of the forearm. Above
the elbow this branch is connected with the smaller internal cutaneous nerve (nerve
of Wrisberg), and afterwards communicates with the outer portion of the internal
cutaneous, and, according to Swan, with the dorsal branch of the ulnar nerve.
c. A branch to the integument of the arm pierces the fascia near the axilla, and
reaches to, or nearly to the elbow, distributing filaments outwards over the biceps
muscle. This branch is often connected with the intercosto -humeral nerve.
SMALL INTERNAL CUTANEOUS NERVE.
The smaller internal cutaneous nerve, or nerve of Wrisberg, destined for
the supply of the integument of the lower balf of the upper arm on the
inner and posterior aspect, commonly arises from the inner cord of the
brachial plexus in union with the larger internal cutaneous and uluar
nerves. In the axilla it lies close to the axillary vein, but it soon appears
on the inner side of that vessel, and communicates with the intercosto-
humeral nerve. It then descends along the inner side of the brachial
vessels to about the middle of the arm, where it pierces the fascia, and its
filaments are thence continued to the interval between the internal condyle
of the humerus and the olecranon.
Branches. — In the lower third of the arm, branches of this small nerve are directed
almost horizontally to the integument on the posterior aspect ; and the nerve ends
at the elbow by dividing into several filaments some of which are directed forwards
over the inner condole of the humerus, while others are prolonged downwards
behind the olecranon.
Connection with the intercosto-humeral nerve. — This connection presents much
variety in different cases : — in some, there are two or more intercommunications, form-
ing a kind of plexus on the posterior boundary of the axillary space ; in others, the
NERVES OF THE UPPER LIMB.
647
intercosto-humeral nerve is of larger size than usual, and takes the place of the nerve
of Wrisberg, only receiving in the axilla a small filament from the brachial plexus ;
Fig. 429.
Fig. 428. — ANTERIOR CUTANEOUS NERYES OF THE SHOULDER AND ARM (from Sappey after
Hirschfeld and Leveilld). I
1, 1, snpraclavicular and supraacromial nerves from the cervical plexus ; 2, 2, 2,
cutaneous branches of the circumflex nerve ; 3, 4, upper branches of the internal cuta-
neous nerve ; 5, superior external cutaneous branch of the musculo- spiral ; 6, internal
cutaneous nerve piercing the deep fascia ; 7, posterior branch ; 8, communicating twig
with one of the anterior branches ; 9, 10, anterior branches of this nerve, some turning
round the median basilic and ulnar veins ; 11, musculo-cutaneous nerve descending over
the median cephalic vein ; 12, inferior cutaneous branch of the musculo-spiral nerve.
Fig. 429. — ANTERIOR CUTANEOUS NERVES OP THE FOREARM AND HAND (from Sappey
after Hirschfeld and Leveille). fe
9, 10, 13, distribution of the anterior branches of the internal cutaneous nerve; 14,
union of one of these with a twig of the ulnar nerve ; 12, inferior cutaneous branch of
the musculo-spiral nerve; 11, 15, distribution of the external cutaneous nerve; 16,
union of one of its branches with 17, the terminal branch of the radial nerve ; 18,
palmar cutaneous branch of the median nerve; 19, 20, internal and external collateral
branches to the thumb from the median nerve ; 21, external collateral to the index
finger ; 22, 23, collateral branches to the index, middle and fourth fingers ; 24, 25,
collateral branches from the ulnar nerve to the fourth and fifth fingers ; the network of
communicating twigs formed by the terminal branches of these cutaneous nerves is repre-
sented at the extremities of the fingers.
648 NER\ES OF THE UPPER LIMB.
and this small communicating filament represents in such cases the nerve of
Wrisberg.
MUSCULO-CUTANEOUS NERVE.
The musculo-cutaneous or external cutaneous nerve (perforans Casserii) in
deeply placed between the muscles as far as the elbow, and below that point
is immediately under the integument. Arising from the brachial plexus
opposite the small pectoral muscle, it perforates the coraco-brachialis muscle,
and, passing obliquely across the arm between the biceps and brachialis
anticus muscles, reaches the outer side of the biceps a little above the
elbow. Here it perforates the fascia, and nearly opposite the elbow-joint it
passes behind the median-cephalic vein, and, inclining outwards, divides
into two branches which supply the integument on the outer side of the
forearm, one on the anterior, the other on the posterior aspect.
A. Branches in the arm : —
a. A branch to the coraco-brachialis and short head of the biceps is given off before
the nerve pierces the former muscle ; and other filaments are furnished to the coraco-
brachialis, while the nerve lies among its fibres.
b. Branches to the biceps and brachialis anticus are given off while the nerve is
between those muscles.
c. Small filaments are given to the humerus and elbow-joint.
B. Branches in the forearm : —
a. The anterior branch descends near the radial border of the forearm. It is
placed in front of the radial artery near the wrist, and distributes some filaments
over the ball of the thumb. Piercing the fascia, it accompanies the artery to the
back part of the carpus. This part of the nerve is connected at the wrist with a
branch of the radial nerve.
b. The posterior branch is directed outwards to the back of the forearm, and
ramifies in the integument of the lower third, extending as far as the wrist. It com-
municates with a branch of the radial nerve, and with the external cutaneous branch
of the musculo-spiral nerve.
Summary. — The musculo-cutaneous nerve supplies the coraco-brachialis,
biceps, and brachialis anticus muscles, and the integument on the outer
side of the forearm. Communications are established between it and the
radial and the external cutaneous branch of the musculo-spiral.
Varieties. — In some cases it does not perforate the coraco-brachialis
muscle. It is frequently found to communicate by a cross branch with or to
be an offset of the median nerve ; and in the latter case, the coraco-brachialis
muscle receives a separate branch from the brachial ploxus, which may be
explained thus, — that the main part of the musculo-cutaneous nerve, instead
of piercing the coraco-brachialis muscle, remains adherent to the outer root
and trunk of the median.
ULNAR NERVE.
The ulnar nerve, the largest branch of the inner cord of the brachial
plexus, descends on the inner side of the artery of the limb as far as the
middle of the arm, then turns backwards through the internal intermuscular
septum with the inferior profunda artery, to reach the interval between the
olecranon and the inner condyle of the humerus. From the axilla to this
place it is covered only by the fascia, and it may be felt through the integu-
ment a little above the elbow. It here passes between the two heads of
the flexor carpi ulnaris, and it remains concealed by that muscle as far as the
middle of the forearm ; it thence extends in a straight course along the'
outer margin of the muscle, between it and the uluar artery, to the outer
ULXAR AXD MEDIAN XEEVES. 649
side of the pisiform bone. Above the wrist it gives off a large dorsal branch
to the hand, and continuing onwards it enters the palm on the surface of
the annular ligament, and divides into muscular and cutaneous branches.
The ulnar nerve gives off no branches in the upper arm.
A. Branches in the forearm : —
a. Articular filaments are given to the elbow-joint as the nerve passes behind it.
Some filaments are also given to the wrist-joint.
b. Muscular branches. — One branch enters the upper part of the flexor carpi
ulnaris, and another supplies the two inner divisions of the deep flexor of the fingers.*
c. Cutaneous branches to the forearm. — These two small nerves arise about the
middle of the forearm by a common trunk. One pierces the fascia, and turning
downwards, joins a branch of the internal cutaneous nerve. This branch is often
absent. The second, a palmar branch, lies on the ulnar artery, which it accompanies
to the hand. This little nerve gives filaments around the vessel, and ramifies in the
integument of the hand, joining in some cases with other cutaneous offsets of the
ulnar or median nerve.
d. Dorsal branch to the hand.— This, large offset, leaving the trunk of the ulnar
nerve two or three inches above the wrist, winds backwards beneath the flexor carpi
ulnaris and divides into branches ; one of these ramifies on the inner side of the
little finger, another divides to supply the contiguous sides of that finger and the
ring finger, while a third joins on the back of the metacarpus with the branch of the
radial nerve which supplies the contiguous sides of the ring and middle finger. The
several posterior digital nerves, now described, are united with twigs directed back-
wards from the anterior digital nerves of the same fingers.
B. Palmar branches: —
a. The deep branch separates from the trunk beyond the annular ligament, and,
dipping down through the muscles of the little finger in company with the deep
branch of the ulnar artery, it follows the course of the deep palmar arch across the
hand. It supplies the short muscles of the little finger as it pierces them ; and as it
lies across the metacarpal bones, it distributes two branches to each interosseous
space — one for the palmar, the other for the dorsal interosseous muscle, and supplies
filaments to the two innermost lumbricales muscles. Opposite the space between the
thumb and the index finger the nerve ends in branches to the adductor pollicis, and
the inner head of the flexor brevis pollicis.
b. The remaining part of the nerve supplies a branch to the palmaris brevis muscle
and small twigs to the integument, and divides into two digital branches.
Digital nerves. — One of these belongs to the ulnar side of the little finger. The
other is connected in the palm of the hand with a digital branch of the median nerve,
and at the cleft between the little and ring fingers, divides into the collateral nerves
for these fingers. The terminal disposition of the digital branches on the fingers is
the same as that of the median nerve, to be presently described.
Summary. — The ulnar nerve gives cutaneous filaments to the lower part
of the forearm (to a small extent), and to the hand on its palmar and
dorsal aspects. It supplies the following muscles, viz., the ulnar flexor of
the carpus, the deep flexor of the fingers (its inner half), the short muscles
of the little finger with the palmaris brevis, the interosseous muscles of the
hand, the two internal lumbricales, the adductor pollicis and the inner
half of the flexor brevis pollicis. Lastly, it contributes to the nervous
supply of the elbow and wrist joints.
MEDIAN NERVE.
The median nerve arises by two roots, one from the outer, the other from
the inner cord of the brachial plexus. Commencing by the union of these
* A case has been recorded in which tlie ulnar nerve supplied also two branches to the
flexor sublimis digitorum (Turner, " Kat. Hist. Review," 1864).
u u
650
NERVES OF THE UPPER LIMB.
Fig. 430. Fig. 431.
10
Fig. 430. — DEEP VIEW OP THE ANTERIOR NERVES OP THE SHOULDER AND ARM (from
Sappey aiter Hirschfeld and Leveille). |
1, musculo-cutaneous nerve ; 2, its twig to the coraco-brachialis muscle ; 3, its branch
to the biceps; 4, its branch to the brachialis anticus ; 5, twig of union with the median
nerve (a variety) ; 6, continuation of the nerve in its cutaneous distribution ; 7, musculo-
spiral nerve in the interval between the brachialis anticus and supinator longus ; 8, inferior
external cutaneous branch of the musculo-spiral ; 9, the internal cutaneous and small
internal cutaneous nerves divided ; 10, anterior branch of the internal cutaneous; 11,
median nerve ; to the inside the ulnar nerve is crossed by the line from 11.
Fig. 431.— DEEP VIEW OP THE ANTERIOR NERVES OF THE FOREARM AND HAND (from
Sappey after Hirschfeld and Leveille). £
12, the median nerve ; 13, its branches to the pronator teres ; 14, branch to the super-
ficial flexor muscles, which have been removed ; 15, branch to the flexor digitorum pro-
fund us ; 16, branch to the flexor longus pollicis ; 17, anterior interosseous branch; 18,
cutaneous palmar branch cut short; 19, branches to the short muscles of the thumb ;
20, 21, collateral branches to the thumb; 22, 23, 24, collateral branches to the second,
third, and fourth fingers ; 25, branch given by the ulnar nerve to the flexor carpi ulnaris ;
26, branch to the flexor digitorum profundus ; 27, cutaneous communicating twig ; 28,
dorsal branch of the ulnar ; 29, superficial palmar branch ; 30, 31, collateral branches
to the fourth and fifth fingers ; 32, deep palmar branch ; 33, its branch to the short
muscles of the little finger ; 34, 35, 36, twigs given by the deep branch of the ulnar to
the third and fouith lurnbricales, all the interossei, and the adductor pollicis.
BRANCHES OF THE MEDIAN NERVE. 651
roots in front or on the outer side of the axillary artery, the nerve descends
in contact with the brachial artery, gradually passing inwards over it,
and near the elbow is at the inner side of the vessel. Crossing the bend of
the arm it passes beneath the pronator radii teres, separated by the deep slip
of that muscle from the ulnar artery, and continues straight down the front
of the forearm, between the flexor sublimis digitorum and flexor profundus.
Arrived near the wrist it lies b.neath the fascia, between the tendons of the
flexor sublimis and that of the flexor carpi radialis. It then enters the
palm behind the annular ligament, and rests on the flexor tendons. Some-
what enlarged, and of a slightly reddish colour, it here separates into two
parts of nearly equal size. One of these (the external) supplies some
of the short muscles of the thumb, and gives digital branches to the thumb
and the index finger ; the second portion supplies the middle finger, and.
in part the index and ring fingers.
The median nerve gives no branch to the upper arm.
A. Branches in the forearm : —
In the forearm the median nerve supplies muscular branches, and, near
the wrist, a single cutaneous filament. All the muscles on the front of the
f jrearm (pronators and flexors), except the flexor carpi ulnaris and part of
the deep flexor of the fingers, are supplied from this nerve.
a. The branches for the superficial muscles are separate twigs given off from the
nerve below or near the elbow-joint, but the branch furnished to the pronator teres
often arises above the joint.
b. Anterior interosseous nerve. — This is the longest branch of the median nerve,
and it supplies the deeper muscles of the forearm. Commencing at the upper part
of the forearm, beneath the superficial flexor of the fingers, it passes downwards
with the anterior interosseous artery on the interosseous membrane, and between
the long flexor of the thumb and the deep flexor of the fingers, to the pronator
quadratus muscle, in which it ends.
c. The cutaneous palmar branch pierces the fascia of the forearm close to the
annular ligament, and, descending over that ligament, ends in the integument of the
palm about the middle : being connected by a twig with the cutaneous palmar branch
of the ulnar nerve. It distributes some filaments over the ball of the thumb, which
communicate with twigs of the radial or the external cutaneous nerve.
B. Branches in the hand : —
a. Branch to muscles of the thumb.— This short nerve subdivides into branches
for the abductor, the opponens, and the outer head of the flexor brevis pollicis muscle.
b. Digital nerves. — These are five in number, and belong to the thumb, and the
fingers as far as the outer side of the ring-finger. As they approach the clefts
between the fingers, they are close to the integument in the intervals between the
longitudinal divisions of the palmar fascia.
The first and second nerves lie along the sides of the thumb ; and the former (the
outer one) is connected with the radial nerve upon the ball of the thumb.
The third, destined for the radial side of the index finger, gives a muscular branch
to the first or most external lumbrical muscle.
The fourth supplies the second lumbricalis, and divides into branches for the
adjacent sides of the index and middle fingers.
The fifth, the most internal of the digital nerves, is connected by a crossing-twig
with the ulnar nerve, and divides to furnish branches to the adjacent sides of the
ring and middle fingers.
Each digital nerve divides at the end of the finger into two branches, one
of which supplies the ball on the fore part of the finger ; the other ramifies
in the pulp beneath the nail. Branches pass from each nerve forwards and
backwards to the integument of the finger; and one larger than the rest
u u 2
652 NERVES OF THE UPPER LIMB.
inclines backwards by the side of the first phalanx of the finger, and, after
joining the dorsal digital nerve, ends in the integument over the last
phalanx.
Fig 432 Fi" 432. — DISTIUBUTION OP THE DIGITAL NERVES (from Hirschfeld and
Leveille). 4
1, palmar collateral nerve ; 2, its final palmar distribution ; 3, its
dorsal or ungual distribution, and between these numbers the network of
terminal filaments ; 4, collateral dorsal nerve ; 5, uniting twigs passing
between the dorsal and palmar digital nerves.
Summary. — The median nerve gives cutaneous branches to
the palm, and to several fingers. It supplies the proiiator
muscles, the flexors of the carpus and the long flexors of the
fingers (except the ulnar flexor of the carpus, and part of the
deep flexor of the fingers), likewise the outer set of the short
muscles of the thumb, and two lumbricales.
Some similarity will be observed between the course and
distribution of the median and ulnar nerves. Neither gives
any offset in the arm. Together they supply all the muscles
in front of the forearm and in the hand, and together they supply the
skin of the palmar surface of the hand, and impart tactile sensibility to all
tho fingers.
MUSCULO-SPIRAL NERVE.
The musculo-spiral nerve, the largest offset of the brachial plexus,
occupies chiefly the back part of the limb, and supplies nerves to the ex-
tensor muscles, as well as to the skin.
Arising behind the axillary vessels from the posterior cord of the brachial
plexus, of which it is the principal continuation and the only one prolonged
into the arm, it soon turns backwards into the musculo-spiral groove, and,
accompanied by the superior profunda artery, proceeds along that groove,
Vet ween the humerus and the triceps muscle, to the outer side of the limb. It
then pierces the external intermuscular septum, and descends in the interval
between the supinator longus and the braohialis anticus muscle to the level of
the outer condyle of the humerus, where it ends by dividing into the radial
and posterior interosseous nerves. Of these, the radial is altogether a cuta-
neous nerve, and the posterior interosseous is the muscular nerve of the back
of tho forearm.
The branches of the musculo-spiral nerve may be classified according as
they arise on the inner side of the humerus, behind that bone, or on the
outer side.
A. Internal branches : —
(a) Muscular branches for the inner and middle heads of the triceps. That for
the inner portion of the muscle is long and slender; it lies by the side of the ulnar
nerve, and reaches as far as the lower third of the upper arm. One branch, previously
noticed by authors, but more particularly described by Krause, is named by him the
ulnar collateral branch.. It arises opposite the outer border of the latissimus dorsi
tendon, and descends within the sheath of the ulnar nerve, through the internal
intermuscular septum, and is distributed to the short inferior fibres of the triceps
(Reichert and Du Bois Reymond's Archiv. 1864).
(b) The internal cutaneous branch of the musculo-spiral nerve, commonly united in
origin with the preceding, winds backwards beneath the intercosto-humeral nerve,
and after supplying filaments to the skin, ends about two inches from the olecranon ;
MUSCULO-SPIRAL,- RADIAL XERVE.
653
in some instances extending as far as the olecranon. This nerve is accompanied by a
small cutaneous artery.
.B. Posterior branches : —
These consist of a fasciculus of muscular branches which supply the outer head of the
triceps muscle and the anconeus. The branch of the anconeus is slender, and remark-
able for its length; it descends in the substance of the triceps to reach its destination.
C. External branches : —
(a) The muscular branches supply the supinator longus, extensor carpi radialis
longior, (the extensor carpi radialis brevior receiving its nerve from the posterior
interosseous,) and occasionally give a small branch to the brachialis anticus.
(6) The external cutaneous branches, two in number, arise where the nerve pierces
the external intermuscular septum.
The upper branch, the smaller of the two, is directed downwards to the fore part
of the elbow, along the cephalic vein, and distributes filaments to the lower half of
the upper arm on the anterior aspect. The lower branch extends as far as the wrist,
distributing offsets to the lower half of the arm, and to the forearm, on their pos-
terior aspect, and is connected near the wrist with a branch of the external cutaneous
Fig. 433. — DORSAL CUTANEOUS NERVES
OP THE HAND. J
The distribution delineated in this
figure is not the most common, there being
a larger than usual branch of the ulnar
nerve : 1, the radial nerve descending
beside the principal radial cutaneous vein ;
2, and 3, dorsal branches to the two sides
of the thumb ; 4, branch to the radial
side of the forefinger ; 5, branch to the
fore finger and middle finger, communi-
cating with one from the ulnar nerve;
6, the posterior branch of the ulnar nerve ;
7, communicating twig ; 8, collateral
branch to the middle and ring fingers ;
9, collateral branch to the ring and little
fingers ; 10, branch to the inner side of
the hand and little finger.
RADIAL NERVE.
The radial nerve, continuing
straight down from the musculo-
spiral, is concealed by the long
supinator muscle, and lies a little
to the outer side of the radial
artery. This position beneath the
supinator is retained to about three
inches from the lower end of the
radius, where the nerve turns back-
wards beneath the tendon of the
muscle, -and becomes subcutaneous.
It then separates into two branches,
which ramify in the integument on
the dorsal aspect of the thumb and the next two fingers in the following
manner.
654
NERVES OF THE TIPPER LIMB.
(a) The external branch extends to the radial side of the thumb, and is joined by an
offset of the external cutaneous nerve. It distributes filaments over the ball of the
thumb.
(b) The internal portion communicates with a branch of the external cutaneous
nerve on the back of the forearm, and divides into digital branches ; one running
along the ulnar side of the thumb, a second on the radial side of the index finger, a
third dividing to supply the adjacent sides of the index and middle fingers, while a
fourth joins with an offset from the dorsal branch of the ulnar, and along with it
forms a branch for the supply of the contiguous sides of the middle and ring
fingers. These branches communicate on the sides of the fingers with the palmar
digital nerves.
Sometimes the interspace between the middle and ring fingers is entirely supplied
by the radial, and at other times entirely by the ulnar nerve.
POSTERIOR INTEROSSEOUS NERVE.
This nerve, the larger of the two divisions of the musculo-spiral nerve,
•winds to the back of the forearm through the fibres of the supinator brevis
Fig. 434.
Fig. 434. — VIEW OP THE RADIAL SIDE OP THE FORE-ARM,
SHOWING THE FINAL DISTRIBUTION OF THE MuSCULO-
SPIRAL NERVE (from Hirschfeld and Leveille). 5
The supinator longus, andextensores carpi radiales longior
and brevior have been divided, and their upper parts re-
moved ; the extensor communis digitorurn is pulled back-
wards by a hook, and the supinator brevis has been par-
tially dissected to show the posterior interosseous nerve
passing through it.
1, placed upon the tendon of the biceps muscle, points
to the musculo-cutaneous nerve ; 1', near the wrist, the
lower part of this nerve and its plexus of union with the
radial nerve ; 2, trunk of the musculo-spiral nerve emerg-
ing from between the brachialis anticus, on which the
number is placed, and the supinator longus muscle ; 2',
its muscular twigs to the long supinator and long radial
extensor of the carpus ; 2", the posterior interosseous nerve
passing through the substance of the supinator brevis : 3,
placed upon the cut lower portion of the supinator longus,
the radial nerve ; 4, the external collateral nerve of the
thumb ; 5, the common collateral of the fore-finger and
thumb ; 6, the common collateral of the fore-finger and
middle finger ; 7, the twig of union with the dorsal branch
of the ulnar nerve ; 8, placed upon the common extensor
of the fingers, the muscular branches of the posterior inter-
osseous nerve to the long extensor muscles ; 9, upon the
extensor secundi internodii pollicis, the branches to the
short extensor muscles.
muscle, and is prolonged between the deep and
superficial layers of the extensor muscles to the
interosseous membrane, which it approaches about
the middle of the forearm.
Much diminished in size by the separation of
numerous branches for the muscles, the nerve lies
at the lower part of the forearm beneath the
extensor of the last phalanx of the thumb and
the tendons of the common extensor of the
fingers, and terminates on the back of the
carpus in a gangliform enlargement, from which filaments are given to the
adjoining ligaments and articulations.
ANTERIOR DIVISIONS OF THE DORSAL NERVES. 655
The branches of the interosseous nerve enter the surrounding muscles,
viz., the extensor carpi radialis brevior and supinator brevis, the superficial
layer of the extensor muscles except the anconeus, and the deep layer of
the same muscles : — that is to say, the nerve supplies the supinators, and
the extensors of the carpus and fingers, with the exception of the supiuator
longus and the extensor carpi radialis longior.
Summary of the Musculo-spiral Nerve.
The trunk of the nerve distributes its branches to the extensor muscles of
the elbow-joint exclusively, with the exception of a filament to the brachialis
anticus, which however receives its principal nerves from another source.
Before separating into its two larga divisions, the nerve gives branches
to two muscles of the forearm, viz., the long supiuator, and the long
radial extensor of the carpus. The posterior iuterosseous division distri-
butes nerves to the remaining muscles on the outer and back part of the
forearm, except the anconeus (previously supplied), viz. , to the short supinator
and the extensors.
Cutaneous nerves are distributed, from the trunk of the nerve and its
radial division, to the lower part of the upper arm, to the forearm, and to
the hand — on the posterior and outer aspect of each.
ANTERIOR PRIMARY DIVISIONS OF THE DORSAL NERVES.
These nerves are twelve in number, and, with the exception of the larger
part of the first of them, which joins the brachial plexus, they are dis-
tributed to the walls of the thorax and abdomen. Eleven of the nerves so
distributed are termed intercostal, and the twelfth is situated below the last
rib. The cords connecting them with the sympathetic nerve, placed close to
the vertebrae, are very short.
The anterior divisions of these nerves pas3 separately to their destination,
without forming any plexus by the connection or interlacement of their
fibres, and in this respect they differ from those of the other spinal nerves.
From the iutervertebral foramina they are directed transversely across the
trunk, and nearly parallel one to another. The upper six nerves, with the
exception of the first, are confined to the parietes of the thorax ; while the
lower six nerves are continued from the intercostal spaces to the muscles
and integument of the anterior wall of the abdomen.
FIRST DORSAL NERVE.
The greater part of the anterior division of this nerve ascends over the
neck of the first rib and the first intercostal artery to enter into the brachial
plexus. The remaining portion of the nerve is continued as the first inter-
costal, a small branch which courses along the first intercostal space, in the
manner of the other intercostal nerves, but has usually no lateral cutaneous
branch, and may also want the anterior cutaneous.
UPPER, OR PECTORAL INTERCOSTAL NERVES.
In their course to the fore part of the chest, these nerves accompany the
intercostal blood-vessels. After a short space they pass between the internal
and external intercostal muscles, supplying them with twigs, and, about
midway between the vertebrae and the sternum, give off the lateral cutaneous
branches. The nerves, greatly diminished, are now continued forwards
amid the fibres of the internal intercostal muscles as far as the costal
cartilages, where they come into contact with the pleura. In approaching
656
THE DORSAL NERVES.
F;c. 4C5.
Fig. 435. — VIEW OF THE ANTERIOR DIVISIONS OP THE DORSAL AND SOME OF THE OTIIEK
SPINAL NERVES PROM BEFORE (from Hirscbfeld and LeveiHe"). £
The pectoralis major and minor muscles have been removed ; on the right side the
rectus abdominis and internal oblique muscles are shown, on the left side the anterior part
of the rectus is cut away, and the transversalis is exposed.
1, The median and other nerves of the brachial plexus ; 2, the internal cutaneous ; 3,
INTERCOSTAL NERVES. 657
the nerve of Wrisberg; 4, the intercostal nerves continued forwards to 4', their anteiior
cutaneous twigs ; 5, the lateral cutaneous branches of these nerves ; 6, cutaneous branch
of the last dorsal spinal nerve ; 7, the iliac twig of the ilio-hypogastric branch of the
first lumbar nerve ; 8, termination of the ilio-hypogastric ; 9, the ilio-iuguinal ; 10, the
middle cutaneous of the thigh.
the sternum, they cross the internal mammary artery and the fibres of the
triangularis sterni muscle. Finally, these nerves pierce the internal inter-
costal muscle and the greater pectoral, and end in the integument of the
breast, receiving the name of the anterior cutaneous nerves of the thorax.
At the anterior part of the chest some of the muscular twigs cross the cartilages
of the ribs, passing from one intercostal space to another.
(a) The lateral cutaneous nerves of the thorax pierce the external intercostal and
serratus magnus muscles, in a line a little behind the pectoral border of the axilla.
The first intercostal usually gives no lateral branch or only a slender twig to the
axilla, but, when that of the second nerve is unusually small, it is supplemented by
that of the first. The branch from the .second intercostal is named intercosto-humeral,
and requires separate description. Each of the remaining lateral cutaneous nerves
divides into two branches, which reach the integument at a short distance from each
other, and are named anterior and posterior.
The anterior branches are continued forwards over the border of the great pectoral
muscle. Several reach the mammary gland and the nipple; and from the lower
nerves twigs are supplied to the digitations of the external oblique muscle of the
abdomen.
The posterior branches turn backwards to the integument over the scapula and the
latissimus dorsi muscle. The branch from the third nerve ramifies in the axilla, and
a few filaments reach the arm.
The intercosto-humeral nerve, the lateral cutaneous branch of the second inter-
costal nerve, corresponds with the posterior of the two divisions of the succeeding
lateral cutaneous branches, the anterior being commonly wanting. It crosses the
axillary space to reach the arm, and is connected in the axilla with an offset of the
nerve of Wrisberg. Penetrating the fascia, it becomes subcutaneous, and ramifies in
the integument of the upper half of the arm, on the inner and posterior aspect ; a
few filaments reach the integument over the scapula. The branches of this nerve
cross over the internal cutaneous offset of the musculo-spiral, and a communication
is established between the two nerves. The size of the intercosto-lmmeral nerve,
and the extent of its distribution, are in the inverse proportion to the size of the
other cutaneous nerves of the upper arm, especially the nerve of Wrisberg.
(b] The anterior cutaneous nerves of the thorax, which are the terminal twigs of the
intercostal nerves, are reflected outwards in the integument over the great pectoral
muscle. The branch from the second nerve is connected with the supraclavicular
and the lateral cutaneous nerves; those from the third and fourth nerves are distri-
buted to the mammary gland.
LOWER, OR ABDOMINAL INTERCOSTAL NERVES.
The lower intercostal nerves are continued from the anterior ends of the
intercostal spaces, between the internal oblique and the transverse muscle of
the abdomen, to the outer edge of the rectus. Perforating the sheath,
they enter the substance of that muscle, and afterwards terminate in small
cutaneous branches (anterior cutaneous).
(a) The lateral cutaneous nerves of the abdomen pass to the integument through
the external intercostal and external oblique muscles, in a line with the correspond-
ing nerves on the thorax, and divide in the same manner into anterior and posterior
branches.
The anterior branches are the larger, and are directed inwards in the superficial
fascia, with small cutaneous arteries, nearly to the edge of the rectus muscle.
The posterior branches bend backwards over the latissimus dorsi muscle.
(b) The anterior cutaneous nerves of the abdomen become subcutaneous near the
658 THE LUMBAR PLEXUS.
linea alba, accompanying the small perforating arteries. Their number and position
are very uncertain. They are directed outwards towards the lateral cutaneous nerves.
A second set is described by Cruveilhier as existing at the outer edge of the rectus
muscle.
LAST DORSAL NERVE.
The anterior primary division of this nerve is below the last rib, and is
contained altogether in the abdominal wall. The nerve has the general
course and distribution of the others between the internal oblique and
transversalis, but, before taking its place between those muscles, it passes in
front of the upper part of the quadratus lumborum, and pierces the posterior
aponeurosis of the transverse muscle. This nerve is connected by offsets
with the nerve above, and occasionally with the ilio-hypogastric branch of
the lumbar plexus. Near the spine it sometimes communicates with the
first lumbar nerve by means of a small cord in the substance of the quad-
ratus lumborum.
The lateral cutaneous branch of the last dorsal nerve^ passing through both
oblique muscles, is directed downwards over the iliac crest to the integument,
covering the fore part of the gluteal region and the upper and outer part of
the thigh, some filaments reaching as far as the great trochanter of the
femur.
ANTERIOR PRIMARY DIVISIONS OF THE LUMBAR NERVES.
The anterior divisions of the lumbar nerves increase in size from the first
to the fifth ; and all, except the fifth, which passes down to join the sacral
nerves, are connected together by communicating loops, so as to form the
lumbar plexus. On leaving the inter vertebral foramina these nerves are
connected by filaments with the sympathetic nerve, these filaments being
longer than those connected with other spinal nerves, in consequence of the
position of the lumbar sympathetic ganglia on the fore part of the bodies of
the vertebrse. In the same situation are furnished small twigs to the psoas
and quadratus lumborum muscles.
LUMBAR PLEXUS.
The lumbar plexus is formed by the communications between the anterior
primary divisions of the four upper lumbar nerves. It is placed in the
substance of the psoas muscle, in front of the transverse processes of the
corresponding vertebrae. Above, the plexus is narrow, and is sometimes
connected with the last dorsal nerve by a small offset from that nerve,
named dorsi-lumbar ; below it is wider, and is joined to the sacral plexus
by means of a branch given by the fourth lumbar nerve to the fifth.
The arrangement of the plexus may be thus stated. The first nerve
gives off the ilio-hypogastric and ilio-inguinal nerves, and sends downwards
a communicating branch to the second nerve. The second furnishes the
greater part of the geuito-crural and external cutaneous nerves, and gives a
connecting branch to the third, from which some of the fibres of the anterior
crural and obturator nerves are derived. From the third nerve, besides the
descending branch to the fourth, two branches proceed : one of these, the
larger, forms part of the anterior crural nerve ; the other, a part of the
obturator nerve. The fourth nerve gives two branches, which serve to
complete the obturator and anterior crural nerves, and a connecting branch
to the fifth nerve.
THE LUMBAR PLEXUS AND NEKVES.
659
The branches of this plexus form two sets, which are distributed, one to
the lower part of the wall of the abdomen, the other to the fore part and
inner side of the lower liinb. In the former set are the ilio-hypogastric and
Fig. 436. — DIAGRAMMATIC
OUTLINE OF THE LUMBAR
AND SACRAL PLEXUSES WITH
THE PRINCIPAL NERVES
ARISING FROM THEM. 4
Fig. 436.
DXIT
DXII, placed opposite the
divided roots of the last dorsal
nerve ; LI to V, opposite the
roots of the five lumbar nerves :
the loops uniting the anterior
primary divisions of these
nerves together, and the first
with the twelfth dorsal are
shown; SI to V, and CI, the
same in the sacral and coccy-
geal nerves ; p, placed on some
of the nerves marks the pos-
terior primary divisions cut
short ; p' p, the plexus formed
by the union of the posterior
branches of the third, fourth,
and fifth sacral and the coccy-
geal nerves ; d, the abdominal
continuation of the last dorsal
nerve, from which d' the iliac
cutaneous branch arises; 1, 1',
the ilio-hypogastric and ilio-
inguinal branches of the first
lumbar nerve ; 2, the genito-
crural rising by a loop from
the first and second lumbar;
2', external cutaneous of the
thigh rising by a loop from the
second and third ; ps, branches
to the psoas muscle along the
lumbar plexus ; cr, anterior
crural nerve from the second,
third, and fourth lumbar; il,
branches to the iliacus ; ob,
obturator nerve from the se-
cond, third and fourth lumbar
nerves ; ob', accessory obtura-
tor; IV, V, loop from the
fourth and fifth lumbar, form-
ing the lumbo- sacral cord ; 3,
superior gluteal nerve ; sc,
sacral plexus ending in the great
sciatic nerve ; 4, lesser sciatic
nerve rising from the plexus
posteriorly; 4', inferior gluteal
branches ; 5, inferior puden-
dal ; 5', posterior cutaneous
of the thigh and leg ; 6, 6,
branches to the obturator in-
ternus and gemellus superior ; 6', 6', branches to the gemellus inferior, quadratus and
hip-joint ; 7, twigs to the pyriformis ; 8, 8, pudic nerve from the first, second, third, and
fourth sacral ; 9, visceral branches ; 9', twig to the levator ani ; 10, cutaneous from the
fourth, which passes round the lower border of the gluteus maximus ; 11, coccygeal
branches.
IV
V
CI
660 THE LUMBAR PLEXUS.
ilio-inguinal nerves, and part of the genito-crural ; and to the latter belong
the remaining part of the genito-crural nerve, the external cutaneous, the
obturator, and the anterior crural nerves.
ILIO-HYPOGASTRIC AND ILIO- INGUINAL NERVES.
These nerves are the upper two branches from the lumbar plexus ; they
are both derived from the first lumbar nerve, and have a nearly similar
distribution. They become subcutaneous by passing between the broad
muscles of the abdomen, and through the outer one, and end in the integu-
ment of the groin and scrotum in the male, and the labia pudendi in the
female, as well as in the integument covering the gluteal muscles. The
extent of distribution of the one is inversely proportional to that of the
other.
The ilio-hypogastric nerve, emerging from the upper part of the psoas
muscle at the outer border, runs obliquely over the quadratus lumborum to
the iliac crest, and there perforating the transverse muscle of the abdomen,
gets between that muscle and the internal oblique, and divides into an iliac
and hypogastric branch.
(a) The iliac branch pierces the attachment of both oblique muscles, immediately
above the iliac crest, and is lost in the integument over the gluteal muscles, behind
the distribution of the lateral cutaneous branch of the last dorsal nerve.
(b) The hypogastric or abdominal branch passes on between the transverse and
internal oblique muscles, and is connected with the ilio-inguinal nerve near the iliac
crest. It then perforates the internal oblique muscle, and, piercing the aponeurosis of
the external oblique, a little above the superficial inguinal opening, is distributed to
the skin of the abdomen above the pubes.
The size of the iliac branch of this nerve varies inversely with that of the lateral
cutaneous branch of the twelfth dorsal. The hypogastric branch is not unfrequently
joined with the last dorsal nerve between the muscles, near the crest of the innominate
bone.
The ilio-inguinal nerve, smaller than the preceding, supplies the integu-
ment of the groin. Descending obliquely outwards over the quadratus
lumborum, it crosses the fibres of the iliacus muscle, being placed lower
down than the ilio-hypogastric : it then perforates the transverse muscle
further forwards than the ilio-hypogastric ; communicating with that nerve
between the abdominal muscles. Then piercing the internal oblique muscle,
it descends in the inguinal canal, and emerging at the superficial inguinal
ring, is distributed to the skin upon the groin, as well as to that upon the
scrotum and penis ia the male, or the labium pudendi in the female, com-
municating with the inferior pudendal nerve. Tn its progress this nerve
furnishes branches to the internal oblique muscle.
The ilio-inguinal nerve occasionally arises from the loop connecting the first and
second lumbar nerves. It is sometimes small, and ends near the iliac crest by joining
the ilio-hypogastric nerve ; in that case the last nerve gives off" an inguinal branch
having a similar course and distribution to the ilio-inguinal nerve, the place of which
it supplies.
GENITO-CRURAL NERVE.
The genito-crural nerve belongs partly to the external genital organs and
partly to the thigh. It is derived chiefly from the second lumbar nerve,
but receives also a few fibres from the connecting cord between that and
the first nerve. The nerve descends obliquely through the psoas muscle,
and afterwards on its fore part, towards Poupart's ligament, dividing at a
variable height into an internal or genital, and an external or crural branch.
GENITO-CRURAL NERVE.
661
It often bifurcates close to its origin from the plexus, in which case its two
branches perforate the psoas muscle in different places.
(a) The genital branch (external spermatic, Schmidt), lies upon or near the external
iliac artery, and sends filaments along that vessel ; then perforating the transversalis
fascia, it passes through the inguinal canal with the spermatic cord, and is lost upon
Fig. 437. — VIEW FROM BEFORE OP TUE ANTERIOR BRANCHES OP THE LUMBAR AND SACRAL
NERVES WITH THE PLEXUSES (from Sappey, after Hirschfeld and Leveille). |
1, lumbar cord of the great sympathetic nerve ; 2, 2', anterior primary divisiun of the
twelfth dorsal nerve ; 3, first lumbar ; 4, 4', ilio-inguinal branch of this nerve ; 5, 5',
ilio-hypogastric branch ; 6, second lumbar nerve ; 7, 7', genito-crural nerve rising from
the first and second lumbar ; 8, 8', external cutaneous nerve of the thigh ; 9, third
lumbar nerve; 10, fourth ; 11, fifth ; 12, lumbo-sacral trunk ; 13, iliac branch of the
ilio-inguinal; 1 4, its abdominal branch; 15, its genital branch; 16, external cutaneous
nerve of the right side passing out of the pelvis under Poupart's ligament ; 17, 17, 17,
cutaneous ramifications of this nerve ; 17', the same nerve exposed on the left side ; 18,
18', genital branch of the genito-crural ; 19, its crural branch on the right side becoming
cutaneous ; 19', the same on the left side exposed as it descends in front of the femoral
artery ; 20, anterior crural nerve ; 21, 21', obturator nerve ; 22, left sciatic plexus ; 23,
aortic plexus of the sympathetic nerve connected superiorly with the other pre-aorti'c
plexuses and the lumbar ganglia, and inferiorly with the hypogastric plexus.
662 THE LUMBAR PLEXUS.
the cremaster muscle. In the female it accompanies the round ligament of the
uterus.
(b) The crural branch (lumbo-inguinal nerve, Schmidt), descends upon the psoas
muscle beneath Poupart's ligament into the thigh. Immediately below that liga-
ment, and at the outer side of the femoral artery, it pierces the fascia lata, and
supplies the skin on the upper part of the thigh, communicating with the middle
cutaneous branch of the anterior crural nerve. Whilst it is passing beneath Pou-
part's ligament, some filaments are prolonged from this nerve on the femoral artery.
It is stated by Schmidt, that when the crural branch of the genito-crural nerve is
large, and commences near the plexus, he has observed it to give a muscular branch
to the lower border of the internal oblique and transversalis muscles.
EXTERNAL CUTANEOUS NERVES.
This nerve, commencing from the loop formed between the second and
third lumbar nerves, on emerging from the outer border of the psoas muscle,
crosses the iliacus muscle below the ilio-inguiual nerve, and passing beneath
Poupart's ligament, reaches the thigh beneath the anterior superior iliac
spine, where it divides into an anterior and a posterior branch distributed to
the integument of the outer side of the hip and thigh.
(a) The posterior branch perforates the fascia lata, and subdivides into two or
three others, which turn backwards and supply the skin upon the outer surface of
the limb, from the upper border of the hip-bone nearly to the middle of the thigh.
The highest among them are crossed by the cutaneous branches from the last dorsal
nerve.
(b) An anterior branch, the continuation of the nerve, is at first contained in a
sheath or canal formed in the substance of the fascia lata ; but, about four inches
below Poupart's ligament, it enters the subcutaneous fatty tissue, and is distributed
along the outer part of the front of the thigh, ending near the knee. The principal
offsets spring from its outer side. In some cases, this branch reaches quite down to
the knee, and communicates there with the internal saphenous nerve.
OBTURATOR NERVE.
The obturator nerve (internal crural) is distributed to the adductor
muscles of the thigh, and to the hip and knee-joints. It arises from the
lumbar plexus by two roots, one from the third and the other from the
fourth lumbar nerve. Having emerged from the inner border of the psoas
muscle, opposite to the brim of the pelvis, it runs along the side of the
pelvic cavity, above the obturator vessels, as far as the opening in the upper
part of the thyroid foramen, through which it escapes from the pelvis into
the thigh. Here it immediately divides into an anterior and a posterior
branch, which are separated from one another by the short adductor
muscle.
A. — The anterior portion communicates with the accessory obturator
nerve, when that nerve is present, and descends in front of the adductor
brevis and behind the pectineus and adductor longus muscles. It gives
branches as follows.
(a) An articular branch to the hip-joint arises near the thyroid membrane.
(b) Muscular branches are given to the gracilis and adductor longus muscles, and
occasionally also others to the adductor brevis and pectineus.
(c) The terminal twig turns outwards upon the femoral artery, and surrounds that
vessel with small filaments.
(d) An offset at the lower border of the adductor longus communicates beneath
the fascia with the internal cutaneous branch of the anterior crural nerve, and with a
branch of the internal saphenous nerve, forming a sort of plexus.
Occasional cutaneous neroe. — In some instances the communicating branch described
OBTURATOR NERVE.— ACCESSORY.
663
is larger than usual, and descends along the posterior border of the sartorius to the
inner side of the knee, where it perforates the fascia, communicates with the internal
saphenous nerve, and extends down the inner side of the limb, supplying the skin as
low as the middle of the leg.
Fig. 438.
Fig. 438. — THE LUMBAR PLEXUS FROM
BEFORE, WITH THE DISTRIBUTION OP
SOME OF ITS NI-.RVES (slightly altered
from Schmidt). |
cr, the last rib ; J, quadratus lura-
boruni muscle ; c, oblique and traus-
verse muscles cut near the crest of the
ilium and turned down ; dt pubes ; e,
adductor brevis muscle ; /, pectineus
dhided and turned outwards ; g, adduc-
tor lougus; 1, ilio-hypogastric nerve ;
2, ilio-inguinal ; 3, external cutaneous;
4, anterior crural ; 5, accessory obtu-
rator ; 6, obturator united with the ac-
cessory by a loop round the pubes; 7,
geuito-crural in two branches cut short
near their origin ; 8, 8, lumbar portion
of the gangliated sympathetic cord.
When this cutaneous branch of the
obturator nerve is present, the internal
cutaneous branch of the anterior crural
nerve is small, the size of the two
nerves bearing an inverse proportion
to each other.
B. — The posterior or deep part
of the obturator nerve, having
passed through some fibres of the
external obturator muscle, crosses
behind the short adductor to the
fore part of the adductor mag-
DUS, where it divides into many
branches, all of which enter those
muscles, excepting one which is prolonged downwards to the knee-joint.
(a) The muscular branches supply the external obturator and the great adductor
muscle, with the short adductor also when this muscle receives no branch from the
anterior division of the nerve.
(b) The articular branch for the knee rests at first on the adductor magnus, but
perforates the lower fibres of that muscle, and thus reaches the upper part of the
popliteal space. Supported by the popliteal artery, and sending filaments around
that vessel, the nerve then descends to the back of the knee-joint, and enters the
articulation through the posterior ligament. (Thomson, " London Med. and Surg.
Journal," No. xcv.)
ACCESSORY OBTURATOR NERVE.
The accespory obturator nerve, a small and inconstant nerve, arising from
the obturator nerve near its upper end, or separately from the same nerves
of the plexus, descends along the inner border of the psoas muscle, over the
pubic bone, and, passing behind the pectineus muscle, ends by dividing into
several branches. Of these one joins the anterior branch of the obturator
nerve ; another penetrates the pectineus on the under surface ; whilst a
third enters the hip-joint with the articular 'artery.
664
THE LUMBAR PLEXUS.
This nerve is sometimes smaller than usual, and ends in filaments which perforate
the capsule of the hip-joint. When it is altogether wanting, the hip-joint receives
branches from the obturator nerve.
Summary. — The obturator nerve and accessory obturator give branches to
the hip and knee joint?, also to the adductor muscles of the thigh, and, in
some cases, to the pecfcineus. Occasionally a cutaneous branch descends to
the inner side of the thigh, and to the inner and upper part of the leg.
Fir. 439.
ANTERIOR CRURAL NERVE.
This nerve is the largest branch of the lumbar plexus, and is derived
piincipally from the third and fourth lumbar nervea, but in part also from
the second. Emerging from the outer
border of the psoas muscle, near its lower
part, it descends into the thigh in the
groove between that muscle and the iliacus,
and, therefore, to the outside of the femoral
blood-vessels. It now becomes flattened
out and divides into two parts, one of
which is cutaneous, while the other is dis-
tributed to muscles.
Fig. 439. — DEEP NERVES OP THE ANTERIOR AND
INNER PART OF THE THIGH (from Sappey after
Hirschfeld and Leveille). ±
1, anterior crural nerve ; 2, branches given to
the iliacus muscle ; 3, branch to the lower pa't of
the psoas ; 4, large musculo-cutaneous branches,
divided to show the deeper nerves ; 5 and 6, mus-
cular filaments from the small musculo-cutaneous ;
7. origin of the cutaneous branches ; 8, communi-
cating filament of the internal cutaneous nerves ;
9, branches to the rectus ; 10, branches to the
vustus externus ; 11, branches to the vastus inter-
ims ; 12, internal saphenous nerve ; 13, its patellar
branch; 14, its continuation down the leg ; 15,
obturator nerve ; 16, branch from the obturator
nerve to the adductor longus ; 17, branch to the
adductor brevis ; 1 8, branch to the gracilis ; from
this a filament is prolonged downwards, to unite
with the plexus formed by the union of branches
from the internal cutaneous and internal saphenous
nerves ; 19, deep branch of the obturator nerve to
the adductor magnus ; 20, lumbo- sacral trunk ; 21,
its union with the first sacral nerve ; 22, 22, lum-
bar and sacral part of the sympathetic nerve ; 23,
external cutaneous nerve from the lumbar plexus.
Branches of the trunk. — The branches
given from the anterior crural nerve within
the abdomen are few and of small size.
(a) The iliacus receives three or four small branches, which are directed outwards
from the nerve to the fore part of the muscle.
(b) The nerve of the femoral artery is a small branch which divides into numerous
filaments upon the upper part of that vessel. It sometimes arises lower down than
i' ;nal in the thigh. It may, on the other hand, be found to take origin above the
ordinary position ; and in this case it proceeds from the middle cutaneous nerve,
ANTERIOR CRURAL NERVE. 660
when that branch springs from or near the lumbar plexus. In either case, its ulti-
mate distribution is the same as that already described.
Terminal branches. — From the principal or terminal divisions of the nerve
the remaining branches take their rise as follows.
From the SUPERFICIAL DIVISION cutaneous branches are given to the fore
part of the thigh, and to the inner side of the leg. They are the middle and
internal cutaneous nerves, and the internal saphenous nerve. One of the
muscles, the sartorius, receives its nerves from this group.
The DEEP BRANCHES supply the muscles on the fore part of the thigh, and
also the pectineus muscle. The branch to the pectineus, however, some-
times arises from the superficial part of the trunk.
A. MUSCULAR BRANCHES.
The branch to the pectineus muscle crosses inwards behind the femoral vessels,
and enters the muscle on the anterior aspect.
The sartorius muscle receives three or four twigs, which arise in common with
the cutaneous nerves, and reach mostly the upper part of the muscle.
The rectus muscle receives a distinct branch on its under surface.
The nerve for the vastus externus, of considerable size, descends with the branches
of the external circumflex artery towards the lower part of the muscle. It gives oft
a long slender articular filament, which reaches the knee and penetrates the fibrous
capsule of the joint.
Another large nerve divides into two sets of branches, which enter the vastus
internus and the crureus about the middle of those muscles. The nerve of the vastus
internus, before penetrating the muscular fasciculi, gives a small branch to the knee-
joint. This articular nerve passes along the internal intermuscular septum with a
branch of the anastomotic artery, as far as the inner side of the joint, where it per-
forates the capsular ligament, and is directed outwards on the synovial membrane
beneath the ligamentum patellae.
B. MIDDLE CUTANEOUS NERVE.
The middle cutaneous nerve either pierces the fascia lata divided into two
branches about four inches below Po apart' s ligament, or as one trunk which
soon separates into two branches. These branches descend side by side on the
fore part of the thigh to the inner side and front of the patella. After or
before the nerve has become subcutaneous, it communicates with the crural
branch of the genito-crural nerve, and also with the internal cutaneous.
This nerve sometimes arises from the anterior crural, high up within the
abdomen.
C. INTERNAL CUTANEOUS NERVE.
The internal cutaneous nerve gives branches to the skin on the inner side
of the thigh, and the upper part of the leg ; but the extent to which it
reaches varies with the presence or absence of the " occasional cutaneous"
branch of the obturator nerve.
Lying beneath the fascia lata, this nerve descends obliquely over the
upper part of the femoral artery. It divides either in front of that vessel,
or at the inner side, into two branches (one anterior, the other internal),
which pierce the fascia separately. These two branches sometimes arise as
distinct offsets from the superficial part of the anterior crural nerve.
The distribution of the internal cutaneous nerve is as follows.
(a) Branches previous to division. — Before dividing into its two ultimate
branches, this nerve gives off two or three cutaneous twigs, which accompany the
upper part of the long saphenous vein. The highest of these perforates the fascia
666
THE LUMBAR PLEXUS.
near the saphenous opening, and reaches down to the middle of the thigh. The
others appear beneath the skin lower down by the side of the vein ; one, larger than
the rest, passes through the fascia about the middle of the thigh, and extends to the
knee. In some instances, these small branches spring directly from the anterior crural
nerve, and they often communicate with each other.
Fig. 440. Fig. 440. — CUTANEOUS NERVES OP THE ANTERIOR
AND INNER PART OF THE THIGH (from Sappey
after Hirschfeld and Leveille). |
1, external cutaneous nerve ; 2, 2, middle cuta-
neous branch of the anterior crural passing through
the sartorius muscle and the fascia ; 3, 3, anterior
division of the internal cutaneous ; 4, filament to
the sartorius ; 5, inner or posterior division of the
internal cutaneous ; 6, its superficial branch to the
inside of the knee after perforating the fascia ; 7,
deep or communicating branch ; 8, superficial
branch of the musculo-cutaneous of the crural ; 9,
patellar branch of the internal saphenous nerve ;
10, continuation of the saphenous down the leg.
(b) The anterior branch, descending in a
straight line to the knee, perforates the fascia
lata in the lower part of the thigh ; it after-
wards runs down near the intermuscular septum,
giving off filaments on each side to the skin, and
is finally directed over the patella to the outer
side of the knee. It communicates above the
joint with a branch of the long saphenous
nerve ; and sometimes it takes the place of the
branch usually given by the latter to the inte-
gument over the patella.
This branch of the internal cutaneous nerve
sometimes lies above the fascia in its whole
length. It occasionally gives off a cutaneous
filament, which accompanies the long saphenous
vein, and in some cases it communicates with
the branch to be next described.
The inner branch of the internal cutaneous
nerve, descending along the posterior border of
the sartorius muscle, perforates the fascia lata
at the inner side of the knee, and communicates
by a small branch with the internal saphenous
nerve, which here descends in front of it. It
gives some cutaneous filaments to the lower
part of the thigh on the inner side, and is dis-
tributed to the skin upon the inner side of the leg. Whilst beneath the fascia, this
branch of the internal cutaneous nerve joins in an interlacement with offsets of the
obturator nerve below the middle of the thigh, and with the branch of the saphenous
nerve nearer the knee.
D. INTERNAL SAPHEXOUS NERVE.
The internal or long saphenous nerve is the largest of the cutaneous
branches of the anterior crural nerve. In some cases it arises in connection
with one of the deep or muscular brandies.
This nerve is deeply placed as far as the knee, and is subcutaneous in the
rest of its course. In the thigh it accompanies the femoral vessels, lying at
first somewhat to their outer side, but lower down approaching close to
ANTERIOR CRURAL.— FIFTH LUMBAR NERVE. 667
them, and passing beneath the same aponeurosis. When the vessels pass
through the opening in the adductor muscle into the popliteal space, the
saphenous nerve separates from them, and is continued downwards beneath
the sartorius muscle to the ianer side of the knee ; where, having first
given off, as it lies near the inner condyle of the femur, a branch which is
distributed over the front of the patella, it becomes subcutaneous by piercing
the fascia between the tendons of the sartorius and gracilis muscles.
The nerve then accompanies the sapheuous vein along the inner side of
the leg, and passing in front of the ankle is distributed to the inner side of
the foot. In the leg it is connected with the internal cutaneous nerve.
The distribution of the branches is as follows.
(a) A communicating branch is given off about the middle of the thigh to join in
the interlacement formed beneath the fascia lata by this nerve and branches of the
obturator and internal cutaneous nerves. After it has left the aponeurotic covering
of the femoral vessels, the internal saphenous nerve has, in some cases, a further
connection with one or other of the nerves just referred to.
(b) The branch to the integument in front of the patella perforates the sartorius
muscle and the fascia lata ; and, having received a communicating offset from the
internal cutaneous nerve, spreads out upon the fore part of the knee ; and, by uniting
with branches of the middle and external cutaneous nerves, forms a plexus — plexus
patellae.
(c) A branch to the inner ankle is given off in the lower third of the leg, and
descends along the margin of the tibia.
(d) Filaments from this nerve enter the tarsal ligaments.
Summary. — The anterior crural nerve is distributed to the skin upon the
fore part and inner side of the thigh, commencing below the termination of the
ilio-inguinal and genito-crural nerves. It furnishes also a cutaneous nerve
to the inner side of the leg and foot. All the muscles on the front and outer
side of the thigh receive their nerves from the anterior crural, and the pec-
tineus is also in part supplied by this nerve, and in part by the obturator.
The tensor muscle of the fascia lata is supplied from a different source,
viz., the superior gluteal nerve. Lastly, two branches are given from the
anterior crural nerve to the knee-joint.
FIFTH LUMBAR NERVE.
The anterior branch of the fifth lumbar nerve, having received a fasciculus
from the nerve next above it, descends to join the first sacral nerve, and
form part of the sacral plexus. The cord resulting from the union of the
fifth with a part of the fourth nerve, is named the lumbo-sacral nerve.
SUPERIOR GLUTEAL NERVE.
Before joining the first sacral nerve the lumbo-sacral cord gives off from
behind the superior gluteal nerve ; this offset leaves the pelvis through the
large sacro-sciatic foramen, above the pyriformis muscle, and divides like
the gluteal artery into two branches, which are distributed chiefly to the
smaller gluteal muscles and tensor of the fascia lata.
(a) The upper branch runs with the gluteal artery along the origin of the gluteus
minimus, and is lost in it and in the gluteus medius.
(b) The lower branch crosses over the middle of the gluteus minimus, between
this and the gluteus medius, and supplying filaments to both those muscles, is con-
tinued forwards, and terminates in the tensor muscle of the fascia lata.
x x 2
668 THE SACRAL NERVES.
ANTERIOR PRIMARY DIVISIONS OF THE SACRAL AND
COCCYGEAL NERVES.
THE SACRAL NERVES.
The anterior divisions of the first four sacral nerves emerge from the
spinal canal by the anterior sacral foramina, and the fifth passes out between
the sacrum and coccyx.
The first two sacral nerves are large, and of nearly equal size ; the others
diminish rapidly, and the fifth is exceedingly slender. Like the anterior
divisions of the other spinal nerves, those of the sacral nerves communicate
with the sympathetic : the communicating cords are very short, as the
sympathetic ganglia are close to the inner margin of the foramina of the
sacrum.
The first three nerves and part of the fourth contribute to form the sacral
plexus. The fifth has no share in the plexus, — it ends on the back of the
coccyx. As the description of the fourth and fifth sacral nerves and of the
coccygeal will occupy only a short space, these three nerves may be noticed
first, before the other nerves and the numerous branches to which they
give rise are described.
THE FOURTH SACRAL NERVE.
Only one part of the anterior division of this nerve joins the sacral
plexus ; the remainder, which is nearly half the nerve, supplies branches to
the viscera and muscles of the pelvis, and sends downwards a connecting
filament to the fifth nerve.
(a) The visceral [branches of the fourth sacral nerve are directed forwards to the
lower part of the bladder, and communicate freely with branches from the sympa-
thetic nerve. Offsets are distributed to the neighbouring viscera, according to the
sex. They will be described with the pelvic portion of the sympathetic nerve. The
foregoing branches are, in some instances, furnished by the third sacral nerve instead
of the fourth, and not unfrequently from both of these nerves.
(b) Of the muscular branches, one supplies the levator ani, piercing that muscle
on the pelvic surface ; another enters the coccygeus, whilst a third ends in the external
sphincter muscle of the rectum. The last branch, after passing either through the
coccygeus, or between it and the levator ani, reaches the perinaeum, and is distributed
likewise to the integuments between the anus and the coccyx.
THE FIFTH SACRAL NERVE.
The anterior branch of this, the lowest sacral nerve, comes forwards
through the coccygeus muscle opposite the junction of the sacrum with the
first coccygeal vertebra ; it then descends upon the coccygeus nearly to the
tip of the coccyx, where it turns backwards through the fibres of that
muscle, and ends in the integument upon the posterior and lateral aspect of
the bone.
As soon as this nerve appears in front of the bone (in the pelvis) it is joined
by the descending filament from the fourth nerve, and lower down by the small
anterior division of the coccygeal nerve. It supplies small filaments to the coccygeus
muscle.
THE COCCYGEAL NERVE.
The anterior branch of the coccygeal, or, as it is sometimes named, the
sixth sacral nerve, is a very small filament. It escapes from the spinal
THE SACRAL PLEXUS.
669
canal by the terminal opening, pierces the sacro-sciatic ligament and the
coccygeus muscle, and, being joined upon the side of the coccyx with the
fifth sacral nerve, partakes in the distribution of that nerve.
THE SACRAL PLEXUS.
The lumbo-sacral cord (resulting as before described from the junction of
Fig. 441.
Fig. 441. — DIAGRAMMATIC
OUTLINE OP THE LUMBAR
AND SACRAL PLEXUSES WITH
THE PRINCIPAL NERYKS
ARISING FROM THEM. ^
The references to the nerves
of the lumbar plexus will be
found at p. 659. DXII,
roots of the last dorsal nerve ;
LI to V, roots of the five
lumbar nerves ; SI to V, and
CI, roots of the five sacral
and the coccygeal nerves ;
IV, V, loop from the an-
terior primary branches of
the fourth and fifth lumbar
nerves, forming the lumbo-
sacral cord ; 3, superior glu-
teal nerve ; SO, sacral plexus
ending in the great sciatic
nerve ; 4, lesser sciatic nerve,
rising from the plexus pos-
teriorly ; 4', inferior gluteal
branches ; 5, inferior puden-
dal ; 5', posterior cutaneous
of the thigh and leg ; 6, 6,
branches to the obturator in-
ternus and gemellus superior ;
6', 6', branches to the ge-
inellus inferior, quadratus and
hip-joint ; 7, twigs to the
pyriformis ; 8, 8, pudic from
the first, second, third, and
fourth sacral ; 9, visceral
branches ; 9', twig to the
levator ani ; 10, cutaneous
from the fourth, which passes
round the lower border of the
gluteus maximus; 11, coccy-
geal branches.
the fifth and part of the
fourth lumbar nerves),
the anterior divisions
of the first three sacral
nerves, and part of the
fourth, unite to form
this plexus. Its con-
struction differs from
that of the other spi-
nal nervous plexuses
in this respest, that the several constituent nerves entering into it
ci
670 THE SACRAL PLEXUS.
unite into one broad flat cord. To the place of union the nerves proceed in
different directions, that of the upper ones being obliquely downwards, while
that of the lower is nearly horizontal ; and, as a consequence of this
difference, they diminish in length from the first to the last. The sacral
plexus rests on the anterior surface of the pyriform muscle, opposite the side
of the sacrum, and escaping through the great sacro-sciatic foramen, ends in
the great sciatic nerve.
Branches. — The sacral plexus gives rise to the great sciatic nerve, and to
various smaller branches ; viz., the pudic nerve, the small sciatic nerve, and
branches to the obturator internus, pyriformis, gemelli, and quadratus
femoris muscles.
MUSCULAR BRANCHES.
a. To the pyriformis muscle, one or more branches are given, either from the plexus
or from the upper sacral nerves before they reach the plexus.
b. The nerve of the internal obturator muscle arises from the part of the plexus
formed by the union of the lumbo-sacral and the first sacral nerves. It turns over
the ischial spine of the hip-bone with the pudic vessels, and is then directed forwards
through the small sacro-sciatic foramen to reach the inner surface of the obturator
muscle.
c. To the levator ani one or more twigs proceed from the lower part of the plexus.
d. The superior gemellus receives a small branch, which arises from the lower part
of the plexus.
e. The small nerve which supplies the lower gemellus and quadratus femoris
muscles springs from the lower part of the plexus. Concealed at first by the great
sciatic nerve, it passes beneath the gemelli and the tendon of the internal obturator,
— between those muscles and the capsule of the hip-joint, — and reaches the deep
(anterior) surface of the quadratus. It furnishes a small articular filament to the
back part of the hip-joint.
THE PUDIC NERVE.
This nerve, arising from the lower part of the sacral plexus, turns over
the spine of the ischium, and then passes forwards through the small sacro-
sciatic foramen, where it usually gives off the inferior hsemorrhoidal branch.
It is next directed along the outer part of the ischio-rectal fossa, in a sheath
of the obturator fascia, along with the pudic vessels, and divides into two
terminal branches, the perinseal nerve and the dorsal nerve of the penis.
A. — The perinceal nerve, the lower and much the larger of the two
divisions of the pudic nerve, lies below the pudic artery, and is expended in
superficial and muscular branches.
a. The superficial perinceal branches are two in number, anterior and posterior.
The posterior branch, which first separates from the perinseal nerve, reaching the back
part of the ischio-rectal fossa, gives filaments inwards to the skin in front of the
anus, and turns forwards in company with the anterior branch to reach the scrotum.
The anterior branch descends to the fore part of the ischio-rectal fossa ; and, passing
forwaids with the superficial perinaeal artery, ramifies in the skin on the fore part of
the scrotum and on the penis. This branch sends small twigs to the levator ani
muscle. The superficial perinseal nerves are accompanied to the scrotum by the
inferior pudendal branch of the small sciatic nerve. The three branches are some-
times named long ncrotal nerves.
In the female, both the superficial perinaeal branches terminate in the external
labium pudendi.
b. The muscular branches generally arise by a single trunk, which is directed
inwards under cover of the transversalis perinaei muscle, and divides into offsets which
PUDIC XEEYE.
671
are distributed to the tranversalis perinaei, erector penis, accelerator urinae, and
compressor urethras.
c. Slender filaments are sent inwards to the corpus spongiosum urethras ; some of
these, before penetrating the erectile tissue, run a considerable distance over its
surface.
Fig. 442.— RIGHT SIPE OF THE Fig. 442.
INTERIOR OP THE MALE PELVIS,
WITH THE PRINCIPAL NERVKS
DISPLAYED (from Hirschfeld and
Leveille). £
The left wall has been removed
as far as the sacrum behind and
the sympbysis pubis in front; the
viscera and the lower part of the
levator ani have been removed ;
a, the lower part of the aorta ; a',
placed on the fifth lumbar ver-
tebra, between the two common
iliac arteries, of which the left is
cut short ; b, the right external
iliac artery and vein ; c, the sym-
physis pubis ; d, the divided py-
riformis muscle, close to the left
auricular surface of the sacrum ;
e, bulb of the urethra covered by
the accelerator urinas muscle ; the
membranous part of the urethra
cut short is seen passing into it ;
1, placed on the crest of the ilium,
points to the external cutaneous
nerve of the thigh passing over
the iliacus muscle ; 2, placed on
the psoas muscle, points to the
genito-crural nerve ; 3, obturator nerve ; 4, 4, placed on the lumbo-sacral cords ; that of
the right side points to the gluteal artery cut short ; 4', the superior gluteal nerve ; 5,
placed on the inside of the right sacral plexus, points by four lines to the anterior divisions
of the four upper sacral nerves, which, with the lumbo-sacral cord, unite in the plexus ;
5', placed on the fifth piece of the sacrum, points to the fifth sacral nerves ; 5", the
visceral branches proceeding from the third and fourth sacral nerves ; 6, placed on the
lower part of the coccyx, below the coccygeal nerves ; 7, placed on the line of division of
the pelvic fascia, points to the nerve of the levator ani muscle ; 8, placed at the lower
border of the great sacro-sciatic ligament, points to the cutaneous nerves of the anus ; 9,
nerve of the obturator internus ; 10, the pudic nerve; 10', is placed above the muscular
branches of the perineal nerve ; 10", the anterior and posterior superficial perineal nerves,
and on the scrotum the distribution of these nerves and the inferior pudendal nerve ; 11,
the right dorsal nerve of the penis; IT, the nerve on the left crus penis which is cut
short ; 12, the continuation of the lesser sciatic nerve on the back of the thigh ; 12', the
inferior pudendal branch ; 13, placed on the transverse process of the fifth lumbar ver-
tebra, marks the lowest lumbar sympathetic ganglion ; 14, placed on the body of the first
piece of the sacrum, points to the upper sacral sympathetic ganglia ; between 14 and 6,
are seen the remaining ganglia and sympathetic nervous cords, as well as their union with
the sacral and coccygeal nerves, and at 6, the lowest ganglion or ganglion impar.
B. — The dorsal nerve of the penis, the upper division of the pudic nerve,
accompanies the pudic artery in its course between the layers of the deep
perinseal or subptibic fascia, and afterwards through the suspensory
ligament, to reach the dorsum of the penis, along which it passes as far as
the glands, where it divides into filaments for the supply of that part. On
672 THE SACRAL PLEXUS.
the penis, this nerve is joined by branches of the sympathetic system, and
it sends outwards numerous offsets to the integument on the upper surface
and sides of the organ, including the prepuce. One large branch penetrates
the corpus cavernosum penis.
In the female, the dorsal nerve of the clitoris is much smaller than the
corresponding branch in the male ; it is similarly distributed.
C. — The inferior hcemorrhoidal nerve arises from the pudic nerve at the
back of the pelvis, or it may come directly from the sacral plexus, and be
transmitted through the small sacro-sciatic foramen to its distribution in the
lower end of the rectum.
Fig. 443.
Fig. 443. — DISSECTION OF THE PERINEUM OP THE MALE TO SHOW THE DISTRIBUTION OP
THE PUDIO AND OTHER NERVES (from Hirschfeld and Leveille). ^
On the right side a part of the glutens maximus muscle and the great sacro-sciatic liga-
ment have been removed to show the descent of the nerves from the great sacro-sciatic
foramen. 1, great sciatic nerve of the right side ; 2, lesser sciatic nerve ; 2', its muscular
branches to the gluteus maximus (right side) ; 2", cutaneous branches to the buttock (left
side) ; 3, continuation of the nerve as posterior middle cutaneous of the thigh ; 3, internal
and external cutaneous branches ; 4, 4, inferior pudendal branch ; 4', network of this and
the perineal nerves on the scrotum ; 5, right pudic nerve ; 6, superior branch or nerve
to the penis ; 7, the external superficial perineal branch ; 7', the internal superficial
perineal branch ; 8, musculo-bulbal branches ; 9, hemorrhoidal or cutaneous anal branches ;
1.0, cutaneous branch of the fourth sacral nerve.
Some of the branches of this nerve end in the external sphincter and in the adjacent
skin of the anus ; others reach the skin in front of that part, and communicate with
the inferior pudendal branch of the small sciatic nerve, and with the superficial
perineal nerves.
Summary. — The pudic nerve supplies the perinsBiim, the penis, and part
of the scrotum, also the urethral and anal muscles in the male ; and the
SMALL SCIATIC NERYE.
673
clitoris, labia, and other corresponding parts in the female. It communicates
with the inferior pudendal branch of the small sciatic nerve.
SMALL SCIATIC NERVE.
The small sciatic nerve (tiervus ischiadicus minor) is chiefly a cutaneous
nerve, supplying the integument of the lower part of the buttock, the back
of the thigh, and upper part of the calf of the leg; it furnishes also branches
to one muscle — the gluteus maximus.
This nerve is formed by the union of two or more nervous cords, derived
from the lower and back part of the sacral plexus. Arising below the pyriform
muscle, it descends beneath the gluteus maximus, and at the lower border
of that muscle comes into contact with the fascia lata. Continuing its
course downwards along the back of the limb, it perforates the fascia a
little below the knee.
Fig. 444.— DEEP NERVES IN THE
GLUTEAL AND INFERIOR PUDENDAL
REGIONS (from Hirschfeld and Le-
veille). \
Fig. 441.
«, back part of the great trochanter ;
b, tensor vaginae feraoris muscle ; ct
tendon of the obturator internus muscle
near its insertion ; d, upper part of the
vastus externus ; e, coccyx ; ft gracilis
muscle ; between /"and cl, the adductor
magnus, semitendinosus, and biceps
muscles ; * placed at the meeting of the
crura penis above the urethia ; 1,
placed upon the ilium close above the
sacro-sciatic notch, marks the superior
gluteal nerve, and on the divided parts
of the gluteus meclius muscle, the supe-
rior branch of the nerve ; 1', on the
surface of the gluteus minimus muscle,
the inferior branch of the nerve ; 1",
branch of the nerve to the tensor vaginae
fernoris ; 2, sacral plexus and great
sciatic nerve ; 2', muscular twig from
the plexus to the pyriformis ; 2", mus-
cular branches to the geraellus superior
and obturator internus ; 3, lesser sciatic
nerve ; 3', placed on the upper and
lower parts of the divided gluteus
maximus, the inferior gluteal muscular branches of the lesser sciatic nerve ; 3", the
cutaneous branches of the same nerve winding round the lower border of the gluteus
maximus ; 4, the continuation of the lesser sciatic nerve as posterior cutaneous nerve of
the thigh ; 4', inferior pudendal branch of the lesser sciatic ; 5, placed on the lower part
of the sacral plexus, points to the origin of the pudic nerve ; 6, its perineal division with,
its muscular branches ; b', anterior or superior superficial perineal branch ; 6", posterior
or inferior superficial perineal ; + + , distribution of these nerves and the inferior puden-
dal on the scrotum ; 7, dorsal nerve of the penis.
The branches of tho small sciatic nerve are as follows.
A. The inferior gluteal branches, given off under the gluteus maximus, supply the
lower part of that muscle. — A distinct gluteal branch commonly proceeds from the
sacral plexus to the upper part of the muscle.
B. The cutaneous branches of the nerve principally emerge from beneath the lower
border of the gluteus maximus, arranged iu an external and an internal set. Others
appear lower down.
674
NERVES OF THE LOWER LIMB.
a. The internal are mostly distributed to the skin of the inner side of the thigh
at the upper part. One branch, however, which is much larger than the rest, is
distinguished as the inferior pudendal.
Fig. 445.
Fig. 445. — POSTERIOR CUTANEOUS NERVES OF THE HIP AND THIGH
(from Hirschfeld and Leveille). £
F a, gluteus maxinms muscle partially uncovered by the removal of a part of the fascia
lata, and divided at its inferior part to show the lesser sciatic nerve ; b, fascia lata over
the glutei muscles and the outer part of the hip ; c, d, part of the semitendinosus, biceps,
and semimembranosus muscles exposed by the removal of the fascia ; e, gastrocnemius ;
/, coccyx ; g, internal branches of the saphena vein ; 1, iliac cutaneous branches of the
ilio-inguinal and ilio-hypogastric nerves ; 2, cutaneous iliac branches of the last inter-
costal ; 3, posterior twigs of the external cutaneous nerve of the thigh ; 4, lesser sciatic
nerve issuing from below the gluteus maximus muscle ; 4', its muscular branches ;
4", its cutaneous gluteal branches ; 5, posterior middle cutaneous continued from
the lesser sciatic ; 5', 5', its inner and outer branches spreading on the fascia of the
thigh ; 6, 6, its terminal branches descending on the calf of the leg ; 7, posterior tibial
and fibular nerves separating in the popliteal space ; 8, lower posterior divisions of the
sacral and coccygeal nerves ; 9, inferior pudendal nerve.
Fig. 446. — DEEP POSTERIOR NERVES OF THE HIP AND THIGH
(from Hirschfeld and Leveilie). |
«, gluteus medius muscle ; I, gluteus maximus ; c, pyriformis ; d, placed on the
GREAT SCIATIC NERVE. 675
trochanter major, points to the tendon of the obturator internus ; e, upper part of the
femoral head of the biceps; f, semitendinosus ; g, semimembranosus ; h, gastrocnemins ;
i, popliteal artery; 1, placed on the gluteus minimus muscle, points to the superior
gluteal nerves ; 2, inferior gluteal branches of the lesser sciatic; 3, placed on the greater
sacro- sciatic ligament, points to the pudic nerve ; 3', its farther course ; 4, inferior
pudendal ; 5, placed on the upper divided part of the semitendinosus and biceps, points
to the posterior middle cutaneous nerve of the thigh ; 6, great sciatic nerve, 6', 6', some
of its muscular branches to the flexors ; 7, internal popliteal or posterior tibial nerve ; 7',
its muscular or sural branches ; 8, external popliteal or peroneal nerve ; 8', its external
cutaneous branch ; 9, communicating tibial ; &', communicating peroneal branch to the
external saphenous nerve.
The inferior pudendal branch turns forwards below the ischial tuberosity to reach
the perinseum. Its filaments then extend forwards to the front and outer part of the
scrotum, and communicate with one of the superficial perineal nerves. In the female,
the inferior pudendal branch is distributed to the external labium pudendi.
b. The external cutaneous branches, two or three in number, turn upwards in a
retrograde course to the skin over the lower and outer part of the great gluteal
muscle. In some instances one takes a different course, descending and ramifying
in the integuments on the outer side of the thigh nearly to the middle.
c. Of the lower branches some small cutaneous filaments pierce the fascia of the
thigh above the popliteal space. One of these, arising somewhat above t'he knee-joint,
is prolonged over the popliteal region to the upper part of the leg.
Of the terminal twigs, perforating the fascia lata opposite the lower part of the
popliteal space, one accompanies the short saphenous vein beyond the middle of the
leg, and others pass into the integument covering the inner and outer heads of the
gastrocnemius muscle. Its terminal cutaneous branches communicate with the short
saphenous nerve.
GREAT SCIATIC NERVE.
The great sciatic nerve (nervus ischiadicus), the largest nerve in the body,
supplies the muscles at the back of the thigh, and by its branches of con-
tinuation gives nerves to all the muscles below the knee and to the greater
part of the integument of the leg and foot. The several joints of the
lower limb receive filaments from it and its branches.
This large nerve is continued from the lower end of the sacral plexus. It
escapes from the pelvis through the great sacro-sciatic foramen, below the pyri-
formis muscle, and reaches down below the middle of the thigh, where it
separates into two large divisions, named the internal and external popliteal
nerves. At first it lies in the hollow between the great trochauter and the
ischial tuberosity, covered by the gluteus maximus and resting on the
gemelli, obturator internus and quadratus femoria muscles, in company with
the small sciatic nerve and the sciatic artery, and receiving from that artery a
branch which runs for some distance in its substance. Lower down it rests
on the adductor magnus, and is covered behind by the long head of the
biceps muscle.
The bifurcation of the sciatic nerve may take place at any point intermediate
between the sacral plexus and the lower part of the thigh ; and, occasionally, it is
found to occur even within the pelvis, a portion of the pyriformis muscle being inter-
posed between the two great divisions of the nerve.
Branches of the trunk. — In its course downwards, the great sciatic nerve
supplies offsets to some contiguous parts, viz., to the hip-joint, and to the
muscles at the back of the thigh.
a. The articular branches are derived from the upper end of the nerve, and enter
the capsular ligament of the hip-joint, on the posterior aspect. They sometimes arise
from the sacral plexus.
676
XERVES OF THE LOWER LIMB.
6. The muscular branches are given off under cover of the biceps muscle ; they
supply the flexors of the leg, viz., the biceps, semitendinosug, and semimembranosus.
A branch is likewise given to the adductor magnus. t
TNTERNAL POPLITEAL NERVE.
The internal popliteal nerve, the larger of the two divisions of the great
sciatic nerve, following the same direction as the parent trunk, continues
along the middle of the popliteal space to the lower border of the popliteus
muscle, beneath which point the continuation of the trunk receives the
name of posterior tibial. The interior popliteal nerve lies at first at a
considerable distance from the popliteal artery,
Fig. 447. at the outer side and nearer to the surface ; but,
from the knee-joint downwards, the nerve,
continuing a straight course, is close behind
the artery, and then crosses it rather to the
inner side.
Fig. 447. — POSTERIOR CUTANEOUS NERVES OF THE LEG
(from Sappey after Hirschfeld and Leveille). £
1, internal popliteal division of the great seiatic nerve ;
2, branch to the internal part of the gastrocnemius
muscle ; 3, 4, branches to the external part and plan-
taris ; 5, communicating branch to the external saphe-
neous nerve ; 6, external popliteal nerve ; 7, cutaneous
branch ; 8, communicating branch descending to unite
with that from the internal popliteal in, 9, the external
saphenous nerve ; 10, calcaneal branch from this nerve ;
11, calcaneal and plantar cutaneous branches from the
posterior tibial nerve; 12, internal saphenous nerve;
13, posterior branches of this nerve.
The inner division of the sciatic nerve, from its
commencement to its partition at the foot, is often
described in anatomical works under the same appel-
lation throughout ; the name varying, however, with
different writers, as for example, " cruralis internus,"
or " popliteus internus," — Winslow : " tibialis pos-
terior,"—Haller : " tibialis vel tibieus," — Fischer, &c.
Branches. — The internal popliteal nerve sup-
plies branches to the knee-joint and to the
muscles of the calf of the leg, and also part of
a cutaneous branch, the external or short sa-
phenous nerve.
ARTICULAR SERVES. — The articular branches are
generally three in number ; two of these accompany
the upper and lower articular arteries of the inner
side of the knee-joint, the third follows the middle
or azygos artery. These nerves pierce the ligamentous tissue of the joint. — The
upper one is often wanting.
MUSCULAR BRANCHES. — The muscular branches of the internal popliteal
nerve arise behind the knee-joint, while the nerve is between the heads of
the gastrocnemius muscle.
a. The nerves to the gastrocnemius consist of two branches, which separate, one
to supply each part of the muscle.
POSTERIOR TIBIAL NERVE. 677
b. The small nerve of the idantaris muscle is derived from the outer of the branches
just described, or directly from the main trunk (internal popliteal).
c. The soleus receives a branch of considerable size, which enters the muscle on the
posterior aspect after descending to it in front of the gastrocnemius.
d. The nerve of the popliteus muscle lies deeper than the preceding branches, and
arises somewhat below the joint ; it descends along the outer side of the popliteal
vessels, and, after turning beneath the lower border of the muscle, enters the deep or
anterior surface.
EXTERNAL OE SHORT SAPHENOUS NERVE.
The cutaneous branch of the internal popliteal nerve (ramus communicans
tibialia) descends along the leg beneath the fascia, resting on the gastro-
cnemius, in the furrow between the heads of the muscle, to about midway
between the knee and the foot. Here it perforates the fascia, and a little
lower down is usually joined by a branch from the external popliteal nerve
(communicans peronei). After receiving this communicating branch, the
external saphenous nerve descends beneath the integument near the outer
side of the tendo Achillis in company with the short saphenous vein, and
turns forwards beneath the outer malleolus to end in the skin at the side of
the foot and on the little toe. On the dorsum of the. foot this nerve com-
municates with the musculo- cutaneous nerve.
In many cases, the external saphenous nerve supplies the outer side of the fourth
toe, as well as the little toe. The union between the saphenous nerve and the branch
cf the external popliteal nerve occurs in some cases higher than usual, occasionally even
at or close to the popliteal space. It sometimes happens that the communication
between the nerves is altogether wanting ; in which case the cutaneous nerve to the
foot is generally continued from the branch of the internal popliteal nerve.
POSTERIOR TIBIAL NERVE.
The internal popliteal nerve receives the name of posterior tibial at the
lower margin of the popliteus muscle. It passes down the leg with the pos-
terior tibial artery, lying for a short distance at the inner side of the vessel,
and afterwards at the outer side ; the artery inclining inwards from its origin
while the nerve continues its straight course. In the interval between the
inner malleolus and the heel, it divides into the two plantar nerves (internal
and external). The posterior tibial nerve, like the accompanying vessels, is
covered at first by the muscles of the calf of the leg, afterwards only by
the integument and fascia, and it rests upon the deep-seated muscles.
Lateral branches. — The deep muscles on the back of the leg and the
integument of the sole of the foot receive branches from the posterior tibial
nerve in its course along the leg.
a. The muscular branches emanate from the upper part of the nerve, either sepa-
rately or by a common trunk ; and one is distributed to each of the deep muscles,
viz., the tibialis posticus, the long flexor of the toes, and the long flexor of the great
toe. The branch which supplies the last-named muscle runs along the peroneal
artery before penetrating the muscle.
b. A calcaneo-plantar cutaneous branch is furnished from the posterior tibial nerve ;
the plantar part perforates the internal annular ligament, and ramifies in the integu-
ment at the inner side of the sole of the foot, and beneath the heel.
INTERNAL PLANTAR NERVE.
The internal plantar, the larger of the two nerves to the sole of the foot,
into which the posterior tibial divides, accompanies the internal or smaller
plantar artery, and supplies nerves to both sides of the three inner toes, and
to one side of the fourth. From the point at which it separates from the
678
NERVES OF THE LOWER LIMB.
posterior tibial nerve, it is directed forwards under cover of the first part of
the abductor of the great toe, and, passing between that muscle and the
short flexor of the toes, it gives off the internal cutaneous branch for the
great toe, and divides opposite the middle of the foot into three digital
branches. The outermost of these branches communicates with the external
plantar nerve.
Brandies. — a. Small muscular branches are supplied to the abductor pollicis and
flexor brevis digitorum.
b. Small plantar cutaneous branches perforate the plantar fascia to ramify in the
integument of the sole of the foot.
c. The digital branches are named numerically from within outwards : the three
outer pass from under cover of the plantar fascia near the clefts between the toes.
The first or innermost branch continues single, but the other three bifurcate to supply
the adjacent sides of two toes. These branches require separate notice.
The first digital branch is that destined for the inner side of the great toe ; it
becomes subcutaneous farther back than the others, and sends off a branch to the
flexor brevis pollicis.
Fi?. 448.
Fig. 448. — SUPERFICIAL AND DEEP DISTRIBUTION OP
THE PLANTAR NERVES (from Hirschf'eld and Le-
veille, slightly modified). J
The flexor communis brevis, the abductor pollicis
and abductor minimi digiti, a part of the tendons
of the flexor communis longus, together with the lum-
bricales muscles, have been removed so as to bring
into view the trans versus and interossei in the middle
of the foot.
a, upon the posterior extremity of the flexor com-
munis brevis, near which, descending over the heel,
are seen ramifications of the calcaneal branch of
the posterior tibial nerve ; b, abductor pollicis ; c,
tendon of the flexor communis longus divided close to
the place where it is joined by the flexor accessorius ;
d, abductor minimi digiti ; e, tendon of the flexor
longus pollicis between the two portions of the flexor
brevis pollicis ; 1, internal plantar nerve giving some
twigs to the abductor pollicis, and 1', a branch to the
flexor communis brevis, cut as it lies on the acces-
sorius ; 2, inner branch of the internal plantar nerve
giving branches to the abductor pollicis, flexor brevis
pollicis, and forming, 2', the internal cutaneous of
the great toe ; 3, continuation of the internal plantar
nerve, dividing subsequently into three branches,
which form, 3', 3', 3', the collateral plantar cutaneous
nerves of the first and second, second and third, and
third and fourth toes ; 4, the external plantar nerve ;
4', its branch to the abductor minimi digiti ; 5, twig
of union between the plantar nerves ; 6, superficial
branch of the external plantar nerve ; subsequently
dividing into 6', 6', the collateral cutaneous nerves of
the fourth and fifth toes and the external nerve of the fifth ; 7, deep branch of the
external plantar nerve giving twigs to the adductor pollicis, the interossei, the trans-
versalis, and to the third and fourth lumbricales muscles.
The second branch having reached the interval between the first and second meta-
tarsal bones, furnishes a small twig to the first lumbricalis muscle, and bifurcates
behind the cleft between the great toe and the second to supply their contiguous
The third digital branch, corresponding with the second interosseous space, gives
a slender filament to the second lumbricalis muscle, and divides in a manner similar
PLANTAR NERVES.— PEROKEAL NERVE. 679
to that of the second branch into two offsets for the sides of the second and third
toes.
The fourth digital branch distributed to the adjacent sides of the third and fourth
toes, receives a communicating branch from the external plantar nerve.
Along the sides of the toes, cutaneous and articular filaments are given from these
digital nerves ; and, opposite the ungual phalanx, each sends a dorsal branch to the
pulp beneath the nail, and then runs onto the ball of the toe, where it is distributed
like the nerves of the fingers.
EXTERNAL PLANTAR NERVE.
The external plantar nerve completes the supply of digital nerves to the
toes, furnishing branches to the little toe and half the fourth : it also gives a
deep branch of considerable size, which is distributed to several of the short
muscles in the sole of the foot. There is thus a great resemblance
between the distribution of this nerve in the foot and that of the ulnar
nerve in the hand.
The external plantar nerve runs obliquely forwards towards the outer side
of the foot, along with the external plantar artery, between the flexor brevis
digitorum and the flexor accessorius, as far as the interval between the
former muscle and the abductor of the little toe. Here it divides into a
superficial and a deep branch, having previously furnished offsets to the
flexor accessorius and the abductor minimi diyiti.
a. The superficial portion separates into two digital branches, which have the same
general arrangement as the digital branches of the internal plantar nerve. They are
distributed thus.
Digital branches. — One of the digital branches continues undivided, and runs
along the outer side of the little toe : it is smaller than the other, and pierces
the plantar fascia further back. The short flexor muscle of the little toe, and occa-
sionally one or two interosseous muscles of the fourth metatarsal space receive
branches from this nerve.
The larger digital branch communicates with an offset from the internal plantar
nerve, and bifurcates near the cleft between the fourth and fifth toes to supply one
side of each.
&. The deep or muscular branch of the external plantar nerve dips into the sole of
the foot with the external plantar artery, under cover of the tendons of the flexor
muscles and the adductor pollicis, and terminates in numerous branches for the fol-
lowing muscles : — all the interossei (dorsal and plantar) except occasionally one or
both of those in the fourth space, the two outer lumbricales, the adductor pollicis,
and the transversalis pedis.
Summary of the internal popliteal nerve. — This nerve supplies all the
muscles of the back of the leg and sole of the foot, and the integument of
the plantar aspect of the toes, the sole of the foot, and in part that of the leg.
EXTERNAL POPLITEAL OR PERONEAL NERVE.
This nerve descends obliquely along the outer side of the popliteal space,
lying close to the biceps muscle. Continuing downwards over the outer
part of the gastrocnemius muscle (between it and the biceps) below the head
of the fibula, the nerve turns round that bone, passing between it and the
peroneus longus muscle, and then divides into the anterior tibial and the
musculo- cutaneous nerves.
Lateral branches. — Some articular and cutaneous branches are derived
from the external popliteal nerve before its final division.
ARTICULAR NERVES. — The articular branches are conducted to the outer
side of the capsular ligament of the knee-joint by the upper and lower
680
NERVES OF THE LOWER LIMB.
articular arteries of that side. They sometimes arise together, and the
upper one occasionally springs from the great sciatic nerve before the bifur-
cation.
From the place of division of the external popliteal nerve, a recurrent
articular nerve ascends through the tibialis anticus muscle with the recur-
rent artery to reach the fore part of the knee-joint.
Fig. 449. Fig. 449. — CUTANEOUS NERVES OF THE
OUTER SIDE OF THE LEG AND FOOT
(from Sappey after Hirschfeld and
Leveille*). £
1, external popliteal nerve ; 2, its
external cutaneous branch ; 3, communi-
cating branch which unites with 4, that
form the internal popliteal in 5, the ex-
ternal saphenous nerve ; 6, calcaneal
branch of the external saphenous; 7,
external dorsal digital branch to the fifth
toe ; 8, collateral dorsal digital branch
of the fourth and fifth toes ; 9, musculo-
cutaneous nerve ; 10, its cutaneous
branches ; 11, loop of union with the
external saphenous; 12, union between
its outer and inner branches ; 13, an-
terior tibial nerve, shown by the removal
of a part of the muscles, and giving
muscular branches superiorly ; 14, its
terminal branch emerging in the space
between the first and second toes, where
it gives the collateral dorsal digital
branches to their adjacent sides ; 15,
branches to the peronei muscles.
CUTANEOUS NERVES. — The cuta-
neous branches, two or three in
number, supply the skin on the
back part and outer side of the
leg.
The peroneal communicating
branch (r. communicans fibularis),
which joins the short sapheuous
nerve below the middle of the
back of the leg, is the largest of
these nerves. In some instances,
it continues a separate branch and
its cutaneous filaments reach down
to the heel or on to the outside of
the foot.
Another cutaneous branch extends along the outer side of the leg to the
middle or lower part, sending offsets both backwards and forwards.
MUSCULO-CUTANEOUS NERVE.
The musculo-cutaneous (peroneal) nerve descends between the peronei
muscles and the long extensor of the toes, and reaches the surface by per-
forating the fascia in the lower part of the leg on the anterior aspect. It
then divides into two branches, distinguished as external and internal,
which proceed to the toes. The two branches sometimes perforate the
fascia at a different height.
PERONEAL NERVE.
681
(a) Muscular branches are given to the peroneus longus and peroneus brevis.
(b) Cutaneous branches given off before the final division are distributed to the lower
part of the leg.
(c) The internal branch of the musculo-cutaneous nerve, passing forwards along
the dorsum of the foot, furnishes one branch to the inner side of the great toe, and
others to the contiguous sides of the second and third toes. It gives other offsets,
which extend over the inner ankle and side of the foot. This nerve communicates
•with the long saphenous nerve on the inner side of the foot, and with the anterior
tibial nerve between the first and second toes.
Fig. 450.
Fig. 450. — VIEW OF THE DISTRIBUTION OP THE
BRANCHES OP THE EXTERNAL POPLITEAL NERVE IN
THE FRONT OP THE LEG AND DORSUM OF THE FOOT
(from Hirschfeld and Leveille').
The upper part of the peroneus longus muscle has
been removed, the tibialis anticus, the long extensor of
the great toe and the peroneus longus have been drawn
separate in the leg by hooks marked a, 6, and c, and
the tendons of the extensor muscles have been removed
in the dorsum of the foot, to show the deeper seated
nerves ; 1, the external popliteal or peroneal nerve
•winding round the other part of the fibula ; 1', its
recurrent articular branches exposed by the dissection
of the upper part of the tibialis anticus muscle ; 2, 2,
the musculo-cutaneous nerve ; 2', 2', twigs to the long
and short peroneal muscles ; 3, internal branch of the
musculo-cutaneous nerve ; 3', 3', its dorsal digital
branches to the inside of the great toe, and to the
adjacent sides of the second and third toes ; 4, the
external branch ; 4', 4', its dorsal digital branches to
the adjacent sides of the third and fourth toes, and in
part to the space between the fourth and fifth toes ;
5, the external saphenous nerve descending on the
outer border of the foot, and uniting at two places
with the outer branch of the musculo-cutaneous ; 5',
its branch to the outer side of the fifth toe ; 6, placed
on the upper part of the extensor communis digitorura,
marks the anterior tibial nerve passing beneath the
muscles ; 6, placed farther down on the tendon of the
tibialis anticus, points to the nerve as it crosses to
the inside of the anterior tibial artery ; 6', its muscular
branches in the leg ; 6", on the tendon of the extensor
longus pollicis points to the anterior tibial nerve after
it has passed into the foot behind that tendon ; 7,
its inner branch uniting with a twig of the musculo-
cutaneous, and giving the dorsal digital nerves to the
adjacent sides of the first and second toes; 8, distri-
bution of its outer branch to the extensor brevis dlgi-
torum and tarsal articulations.
(d) The external branch, larger than the internal
one, descends over the foot towards the fourth toe,
which, together with the contiguous borders of the
third and fifth toes, it supplies with branches.
Cutaneous nerves, derived from this branch, spread over the outer ankle and the
outer side of the foot, where they are connected with the short saphenous nerve.
The dorsal digital nerves are continued on to the last phalanges of the toes.
The number of toes supplied by each of the two divisions of the musculo-cuta-
neous nerve is liable to vary ; together these nerves commonly supply all the toes on
the dorsal aspect, excepting the outer side of the little toe, which receives a branch
from the short saphenous nerve, and the adjacent sides of the gre.it toe and the second
toe, to which the anterior tibial nerve is distributed : with this latter branch, how-
ever, it generally communicates.
Y Y
682 SYNOPSIS OF CUTANEOUS NERVES.
ANTERIOR TIBIAL NERVE.
The anterior tibial (interosseous nerve), commencimg between the fibula
and the ]:eroneus longus, inclines obliquely beneath the long extensor of
the toes to the fore part of the interosseous membrane, and there comes
into contact with the anterior tibial vessels, and with those vessels it
descends to the front of the ankle-joint, where it divides into an external
and an internal branch. The nerve first reaches the outer side of the
anterior tibial artery, above the middle of the leg ; and, after crossing in
front of that vessel once or oftener, lies to the inner side of it at the bend
of the ankle.
(a) Muscular branches. — In its course along the leg, the anterior tibial nerve
gives slender filaments to the muscles between which it is placed, namely, the tibialis
anticus, the long extensor of the toes, and the special extensor of the great toe.
(b) The external branch of the anterior tibial nerve turns outwards over the tarsus
beneath the short extensor of the toes ; and, having become enlarged (like the pos-
terior interosseous nerve on the wrist) terminates in branches which supply the short
extensor muscle, and likewise the articulations of the foot.
(c) The internal branch, continuing onwards in the direction of the anterior tibial
nerve, accompanies the dorsal artery of the foot to the first interosseous space, and
ends in two branches, which supply the integument on the neighbouring sides of the
great toe and the second toe on their dorsal aspect. It communicates with the inter-
nal division of the musculo-cutaneous nerve.
Summary of the external popliteal nerve. — This nerve supplies, besides
articular branches to the knee, ankle, and foot, the peronei muscles, extensor
muscles of the foot, also the integument of the front of the leg and dorsum
of the foot. It gives the ramus communicans fibularis to the short
saphenous branch of the internal popliteal nerve, and communicates with
the long saphenous nerve.
SYNOPSIS OF THE CUTANEOUS DISTRIBUTION OF THE
CEREBRO-SPiNAL NERVES.
HEAD. — The face and head in front of the ear are supplied with sensory
nerves from the fifth cranial nerve. The ophthalmic division supplies
branches to the forehead, upper eyelid, and dorsum of the nose. The
superior maxillary division supplies the cheek, ala of the nose, upper lip,
lower eyelid, and the region behind the eye, over the temporal fascia. The
inferior maxillary division supplies the chin and lower lip, the pinna of the
ear on its outer side, and the integument in front of the ear and upwards to
the vertex of the head.
The head, behind the ear, is mainly supplied by the great occipital branch
of the posterior division of the second spinal nerve, but above the occipital
protuberance there is also distributed the branch from the posterior division of
the third spinal nerve ; and, rn front of the area of the great occipital nerve, is
a space supplied by anterior divisions of spinal nerves, viz., the back of the
pinna of the ear, together with the integument behind and that in front over
the parotid gland, which are supplied by the great auricular nerve ; while
between the area of that nerve and the great occipital the small occipital
nerve intervenes. The auricular branch of the pneumo-gastric nerve also
is distributed on the back of the ear.
TRUNK. — The posterior divisions of the spinal nerves supply an area,
extending on the back from the vertex of the skull to the buttock. This
area is narrow in the neck ; it is spread out over the back of the scapula ;
SYNOPSIS OF CUTANEOUS NERYES. 683
and on the buttock the distribution of the lumbar nerves extends to the
trochanters.
The area supplied by the cervical plexus, besides extending upwards, as
already mentioned, on the lateral part of the skull, stretches over the
front and sides of the neck, and the upper part of the shoulder and breast.
The area of the anterior divisions of the dorsal and Jirst lumbar nerves meets
superiorly with that of the cervical plexus, and posteriorly with that of the
posterior divisions of dorsal and lumbar nerves. It passes down over the
haunch and along by the outer part of Pou part's ligament, and includes
part of the scrotum and a small portion of the integument of the thigh
internal to the saphenous opening.
The perinceum and penis are supplied by the pudic nerve ; the scrotum by
branches of the pudic, inferior pudendal, and ilio- inguinal nerves.
UPPER LIMB. — The shoulder, supplied superiorly by the cervical plexus,
receives its cutaneous nerves iuferiorly as far as the insertion of the deltoid
from the circumflex nerve.
The arm internally is supplied by the intercosto-humeral nerve and the
nerve of Wrisberg. The iuner and anterior part is supplied by the internal
cutaneous nerve ; and the posterior and outer part by the internal and
external branches of the musculo-spiral nerve.
The forearm, anteriorly and on the outer side, is supplied by the
external cutaneous ; on its outer and posterior aspect, superiorly by the
external cutaneous branches of the musculo-spiral, and inferiorly by the
radial branch of the same nerve. On the inner side, both in front and
behind, is the internal cutaneous nerve, and inferiorly are branches of the
ulnar.
On the back of the hand are the radial and uluar nerves, the radial
supplying about three fingers and a half or less, and the uluar one and a
half or more.
On the front of the hand, the median nerve supplies three fingers and a
half, and the ulnar one and a half. In the palm is a branch of the median
given off above the wrist. On the ball of the thumb are branches of the
mu- culo-cutaneous, median, and radial nerves.
LOWER LIMB. — The buttock is supplied from above by the cutaneous
branches of the posterior divisions of the lumbar nerves, with the ilio-hypo-
gastric and lateral branches of the last dorsal nerves ; internally by the
posterior divisions of the sacral nerves ; externally by the posterior branch
of the external cutaneous nerve proceeding from the front ; and inferiorly
by branches of the small sciatic nerve proceeding from below.
The thigh is supplied externally by the external cutaneous nerve ;
posteriorly, and in the upper half of its ii.ner aspect, by the small sciatic ;
anteriorly, and in the lower half of the inner aspect, by the middle and
internal cutaneous.
The leg is supplied posteriorly by the small sciatic and short saphenous
nerves ; internally by the long saphenous and branches of the internal
cutaneous of the thigh ; and outside and in front by cutaneous branches of
the external popliteal nerve, and by its musculo- cutaneous branch.
On the dorsum of the foot are the branches of the mu^culo-cutaneous,
supplying all the toes with the exception of the adjacent sides of the first
and second, which are supplied by the anterior tibial, and the outer side of
the little toe, which, with the outer side of the foot, is supplied by the short
saphenous nerve. The long saphenous is the cutaneous nerve on the inner
side of the foot.
Y Y 2
684 SYNOPSIS OF MUSCULAR NERVES.
The sole of the foot is supplied by the plantar nerves. The internal
plantar nerve gives branches to three toes and a half ; the external to the
remaining one toe and a half.
SYNOPSIS OF THE MUSCULAR DISTRIBUTION OF THE
CEREBRO-SPINAL NERVES.
MUSCLES OF THE HEAD AND FORE PART OF THE NECK.
The muscles of the orbit are mostly supplied by the third cranial nerve —
the superior division of that nerve being distributed to the levator palpebrzo
and the superior rectus muscles ; and the inferior division to the inferior and
internal recti and the inferior oblique. The superior oblique muscle is supplied
by the fourth nerve, the external rectus by the sixth ; while the tensor
tarsi has no special nerve apart from those of the orbicularis palpebrarum,
which are derived from the facial.
The superficial muscles of the face and scalp, which are associated in their
action as a group of muscles of expression, are supplied by the portio dura
of the seventh cranial nerve ; the retrahens auriculam arid occipitalis
muscles being supplied by the posterior auricular branch.
The deep muscles of the face, employed in mastication, viz., the temporal,
masseler, buccinator, and two pterygoid muscles, are supplied by the inferior
maxillary division of the fifth cranial nerve.
Muscles above the hyoid bone. — The mylo-hyoid muscle and anterior belly
of the digastric are supplied by a special biauch of the inferior maxillary
division of the fifth cranial nerve ; the posterior belly of the digastric
muscle, and the stylo-hyoid, are supplied by branches of the portio dura. The
genio-hyoid and the muscles of the tongue receive their nervous supply
from the hypoglossal nerve.
The muscles ascending to the hyoid bone and laiynx, viz., the sterno-hyoid,
omo-hyoid, and sterno-thyroid, are supplied from the ramns descendens noni
and its loop with the cervical plexus, while the thyro-hyoid muscle receives
a separate twig from the ninth nerve.
The larynx, pharynx, and soft palate. — The crico- thyroid muscle is sup-
plied by the external laryngeal branch of the pneumo-gastric nerve, and the
other intrinsic muscles of the larynx by the recurrent laryngeal. The
muscles of the pharynx are supplied principally by the pharyngeal branch of
the pneumo -gastric ; the stylo-pharyngeus, however, is supplied by the
glosso-pharyngeal nerve. Of the muscles of the soft palate unconnected
with the tongue or pharynx, the tensor palati receives its nerve from the otic
ganglion (which also supplies the tensor tympani); the levator palati gets a
twig (Meckel) from the posterior palatine branch of the spheno-palatiue
ganglion, and the azygos uvulee is probably supplied from the same source.
MUSCLES BELONGING EXCLUSIVELY TO THE TRUNK, AND MUSCLES
ASCENDING TO THE SKULL.
All those muscles of the back which are unconnected with the upper limb,
viz., the posterior serrati, the splenius, complexus, erector spiuse, and the
muscles more deeply placed, receive their supply from the posterior divisions
of the spinal nerves.
The sterno-mastoid is supplied by the spinal accessory nerve and a twig
of the cervical plexus coming from the second cervical nerve.
SYNOPSIS OF MUSCULAR NERVES. 6?5
The rectus capitis anticus major ar,d minor are supplied by twigs from the
upper cervical nerves ; the longus colli and scaleni muscles by twigs from
the lower cervical nerves.
The muscles of the chest, viz , the intercostals, subcostals, levatores cos-
tarum, arid triangularis sterni, are supplied by the intercostal nerves.
The obliqui, transversus, and rectus of the abdomen are supplied by the
lower intercostal nerves ; and the oblique and transverse muscles also get
branches from the ilio-inguiual and ilio hypogastric nerves. The cremaster
muscle is supplied by the genital branch of the genito-crural nerve.
The quadratus lumborum (like the psoas) receives small branches from
the lumbar nerves before they form the plexus.
The diaphragm receives the phrenic nerves from the fourth and fifth cer-
vical nerves, and likewise sympathetic filaments from the plexuses round the
phrenic arteries.
The muscles of the urethra and penis are supplied by the pudic nerve ;
the levator and sphincter ani by the pudic an.l by the fourth and fifth
S'icrai and the coccygeal nerves ; and the coccyyeus muscle by the three last
named nerves.
MUSCLES ATTACHING THE UPPER LIMB TO THE TRUNK.
The trapezius and the sterno-cleido-mastoid receive the distribution of the
spinal accessory nerve, and, in union with it, filaments from the cervical
plexus.
The latissimus dorsi receives the long subscapular nerve.
The rhomboidei are supplied by a special branch from the anterior
division of the fifth cervical nerve.
The levator anguli scapulae is supplied by branches from the anterior
division of the third cervical nerve, and sometimes partly also by the branch
to the rhomboid muscles.
The serratus majnus has a special nerve, the posterior thoracic, derived
from the fifth and sixth cervical nerves.
The subclavius receives a special branch from the place of union of the
fifth and sixth cervical nerves.
The pectorales are supplied by the anterior thoracic branches of the
brachial plexus, the larger muscle receiviug filaments from both these
nerves, and the smaller from the inner only.
MUSCLES OF THE UPPER LIMB.
Muscles of the shoulder. — The supraspinatus and infraspinatus are sup-
plied by the suprascapular nerve ; the subsoapularis by the two smaller
subscapular nerves ; the teres major by the second subscapular, and the
deltoid and teres minor by the circumflex nerve.
Posterior muscles of the arm and forearm. — The triceps, anconeus, supi-
nator longus, and extensor carpi radialis Lmgior are supplied by direct branches
of the musculo-spiral nerve ; while the extensor carpi radialis brevior and the
other extensor muscles iti the forearm receive their branches from the pos-
terior iuterosseous division of that nerve.
Anterior muscles of the arm and forearm. — The coraco-brachialis, biceps,
and brachialis anticus are supplied by the musculo- cutaneous nerve : the
brachialis anticus likewise generally receives a twig from the musculo-
spiral nerve. The muscles in front of the forearm are supplied by the
median nerve, with the exception of the flexor carpi uluaris and the
ulnar half of the flexor profuudus digitorum, which are supplied by the
G86 THE SYMPATHETIC NERVES.
ulnar nerve, and the supinator longus, which is supplied by the musculo-
spiral.
Muscles of the hand. — The abductor and opponens pollicis, the outer half
of the flexor brevis pollicis, and the two outer lumbricales muscles, are
supplied by the median nerve : all the other muscles receive their nerves
from the ulnar.
MUSCLES OF THE LOWER LIMB.
Posterior muscles of the hip and thigh. — The gluteus maximus is mainly
supplied by the small sciatic nerve, and receives at its upper part a separate
branch from the sacral plexus. The gluteus medius and minimus, together
with the tensor vaginse femoris, are supplied by the gluteal nerve. The pyri-
formis, gemelli, obturator iiiternus, and quadratus femoris receive special
branches from the sacral plexus. The hamstring muscles are supplied by
branches from the great sciatic nerve.
Anterior and internal muscles of the thigh. — The psoas muscle is supplied
by separate twigs from the lumbar nerves. The iliacus, quadriceps extensor
femoris, and sartorius are supplied by the anterior crural nerve. The
adductor muscles, the obturator externus and the pectineus, are supplied
by the obturator nerve, but the adductor maguus likewise receives a branch
from the great sciatic, and the pectineus sometimes has a branch from the
anterior crural.
Anterior muscles of the leg and foot. — The muscles in front of the leg,
together with the extensor brevis digitorum, are supplied by the anterior
tibia! nerve.
The peroneus longus and brevis are supplied by the musculo-cutaneous
nerve.
Posterior muscles of the leg. — The gastrocnemius, plantaris, soleus, and
popliteus are supplied by branches from the internal popliteal nerve ; the
deep muscles, viz., the flexor longus digitorum, flexor longus pollicis, and
tibialis posticus, derive their nerves from the posterior tibial.
Plantar muscles. — The flexor brevis digitorum, the abductor and flexor
brevis pollicis, and the two inner lumbricales, are supplied by the internal
plantar nerve ; all the others, including the flexor accessorius and iuterossei,
are supplied by the external plantar nerve.
III. SYMPATHETIC NERVES.
The nerves of the sympathetic system (nervus intercostalis ; nerves of
organic life — Bichat) are distributed in general to all the internal viscera,
but some organs receive their nerves also from the cerebro spinal system,
as the lungs, the heart, and the upper and lower parts of the alimentary
canal. It appears from physiological researches to be also the special
province of the sympathetic system to supply nerves to the coats of the
blood-vessels.
This division of the nervous system consists of a somewhat complicated
collection of ganglia, cords and plexuses, the parts of which may, for con-
venience, be classified in three groups, viz., the principal gangliated cords,
the great prevertebral plexuses with the nerves proceeding from them, and
the ganglia of union with cranial nerves.
The gangliated cords consist of two series, in each of which the ganglia are
connected by intervening cords. These cords are placed symmetrically in.
GAXGLIATED SYMPATHETIC COEDS.
687
front of the vertebral column, and extend
from the base of the skull to the coccyx.
Superiorly they are connected with plex-
uses which enter the cranial cavity, while
iuferiorly they converge on the sacrum,
and terminate in a single ganglion on the
coccyx. The several portions of the cords
are distinguished as cervical, dorsal, lum-
bar, and sacral, and iu each of these parts
the ganglia are equal in number, or nearly
so, to the vertebrae on which they lie,
except in the neck, where there are only
three.
Fig. 451. — DIAGRAMMATIC OUTLINE OF THE SYM-
PATHETIC CORD OF ONE SIDE IN CONNECTION
WITH THE SPINAL NERVES.
The full description of this figure will be found
at p. 629.
On the right side the following letters in-
dicate parts of the sympathetic nerves ; viz.
a, the superior cervical ganglion, communi-
cating with the upper cervical spinal nerves
and continued below into the great sympathetic
cord ; 6, the middle cervical ganglion ; c, d, the
lower cervical ganglion united with the first
dorsal ; d', the eleventh dorsal ganglion ; from
the fifth to the ninth dorsal ganglia the origins
of the great splanchnic nerve are shown ; I, the
lowest dorsal or upper lumbar ganglion ; ss, the
upper sacral ganglion. In the whole extent of the
sympathetic cord, the twigs of union with the
spinal nerves are shown.
Connection of the ganyliated cords with
the c&rebro-spinal system. — The ganglia are
severally connected with the spinal nerves
in their neighbourhood by means of short
cords ; each connecting cord consisting of
a white and a grey portion, the former
of which may be considered as proceeding
from the spinal nerve to the ganglion,
the latter from the ganglion to the spinal
nerve. At its upper end the gangliated
cord communicates likewise with certain
cranial nerves. The main cords interven-
ing between the ganglia, like the smaller
ones connecting the ganglia with the spinal
nerves, are composed of a grey and a white
part, the white being continuous with the
fibres of the spinal nerves prolonged to the
ganglia.
The great prevertebral plexuses comprise
three large aggregations of nerves, or
nerves and ganglia situated in front of
the spine, and occupying respectively the
thorax, the abdomen, and the pelvis,
They are single and median, and are
Fig. 451.
Br
688 THE SYMPATHETIC NERVES.
named respectively the cardiac, the solar, and the hypogastric plexus.
These plexuses receive branches from both the gangliated cords above
noticed, and they constitute centres from which the viscera are supplied
with nerves.
The cranial ganglia of the sympathetic are the ophthalmic, spheno-pala-
tine, subrn axillary, and otic, which, being intimately united with the fifth
cranial nerve, have already been described along with that nerve. They
nre also more or less directly connected with the upper end of the sympa-
thetic gangliated cords ; but it will be unnecessary to give any special
description of them in this place.
A. THE GANGLIATED COEDS.
THE CERVICAL PART.
In the neck, each gangliated cord is deeply placed behind the sheath of
the great cervical blood-vessels, and in contact with the muscles which
immediately cover the fore part of the vertebral column. It comprises
three ganglia, the first of which is placed near the base of the skull, the
second in the lower part of the neck, and the third immediately above the
head of the first rib.
THE UPPER CERVICAL GANGLION.
This is the largest ganglion of the great sympathetic cord. It is continued
p.uperiorly into an ascending branch, and tapers below into the connecting
cord, so as to present usually a fusiform shape ; but there is considerable
variety in this respect in different cases, the ganglion being occasionally
broader than usual, and sometimes constricted at intervals. It has the
reddish-grey colour characteristic of the ganglia of the sympathetic system.
It is placed on the larger rectus muscle, opposite the second and third
cervical vertebrae, and behind the internal carotid artery.
Connection with spinal nerves. — At its outer side the superior cervical
ganglion is connected with the first four spinal nerves, by means of slender
cords, which have the structure pointed out in the general description as
being common to the series.
The circumstance of this ganglion being connected with so many as four spinal
nerves, together with its occasionally constricted appearance, is favourable to the
view that it may be regarded as consisting of several ganglia which have coalesced.
Connection irith cranial nerves. — Small twigs connect the ganglion or
its cranial cord with the second ganglion of the pneumo-gastric, and with
the ninth cranial nerve, near the base of the skull ; and another branch,
which is directed upwards from the ganglion, divides at the base of the
skull into two filaments, one of which ends in the second (petrosal) ganglion
of the glosso-pharyngeal nerve ; while the other, entering the jugular
foramen, joins the ganglion of the root of the pneumo-gastric.
Besides the branches connecting it with cranial and spinal nerves, the
first cervical ganglion gives off also the ascending branch, the upper cardiac
nerve, pharyngeal nerves, and branches to blood-vessels.
1. ASCENDING BRANCH AND CRANIAL PLEXUSES.
The ascending branch of the first cervical ganglion is soft in texture and of
CAROTID BRANCH AND PLEXUS. 689
a reddish tint, seeming to be in some degree a prolongation of the ganglion
itself. In its course to the skull, it is concealed by the internal carotid
artery, with which it enters the carotid canal in the temporal bone, and it is
then divided into two parts, which are placed one on the outer, the other on
the inner side of the vessel.
Fig. 452
Fig. 452. — CONNECTIONS OP THE SYMPATHETIC NERVE THROUGH ITS CAROTID BRANCH
WITH SOME OP THE CRANIAL NERVES.
The full description of this figure will be found at p. 602. The following numbers
refer to sympathetic nerves and their connections : — 6, spheno-palatine ganglion ; 7,
Vidian nerve ; 9, its carotid branch ; 10, a part of the sixth nerve, receiving twigs from
the carotid plexus of the sympathetic; 11, superior cervical sympathetic ganglion; 12,
its prolongation in the carotid branch ; 15, anastomosing nerve of Jacobson ; 16, twig
uniting it to the sympathetic.
The external division distributes filaments to the internal carotid artery,
and, after communicating by means of other filaments with the internal
division of the cord, forms the carotid plexus.
The inner division, rather the smaller of the two, supplies filaments to
the carotid artery, and goes to form the cavernous plexus. The terminal
parts of these divisions of the cranial cord are prolonged on the trunk of the
internal carotid, and extend to the cerebral and ophthalmic arteries, around
which they form secondary plexuses, those on the cerebral artery ascending
to the pia mater. One minute plexus enters the eye-ball with the central
artery of the retina.
It was stated by Ribes (Mem. de la Socie"te Med. d'Emulation, torn. viii. p. 606,) that
the cranial prolongations of the sympathetic nerve from the two sides coalesce with
one another on the anterior communicating artery, — a small ganglion or a plexus
being formed at the point of junction; but this connection has not been satis-
factorily made out by other observers.
CAROTID PLEXUS. — The carotid plexus, situated on the outer side of the
internal carotid artery at its second bend (reckoning from below), or between
the second and third bends, joins the fifth and sixth cranial nerves, and
gives many filaments to the vessel on which it lies.
Branches. — (a) The connection with the sixth nerve is established by means of one
or two filaments of considerable size, which are supplied to that nerve where it lies
by the side of the internal carotid artery.
690 THE SYMPATHETIC NERVES.
(6) The filaments connected with the Gasserian ganglion of the fifth nerve pro-
ceed sometimes from the carotid plexus, at others from the cavernous.
(c) The deep branch of the Vidian nerve passes backwards to the carotid plexus,
and after leaving the Vidian canal, lies in the cartilaginous substance which closes
the foramen lacerum medium. Valentin describes nerves as furnished to the dura
mater from the carotid plexus.
CAVERNOUS PLEXUS. — The cavernous plexus, named from its position in
the sinus of the same name, is placed below and rather to the inner side of
the highest turn of the internal carotid artery. Besides giving branches on
the artery, it communicates with the third, the fourth and the ophthalmic
of the fifth cranial nerves.
Blanches. — (a) The filament which joins the third nerve comes into connection
with it close to the point of division of that nerve.
(b) The branch to the fourth nerve, which may be derived from either the caver-
nous or the carotid plexus, joins the nerve where it lies in the wall of the cavernous
sinus.
(c) The filaments connected with the ophthalmic trunk of the///* nerve are supplied
to its inner surface. One of them is continued forwards to the lenticular ganglion,
either in connection with or distinct from the nasal nerve.
2. PHARYNGEAL NERVES AND PLEXUS.
These nerves arise from the inner part of the ganglion, and are directed
obliquely inwards to the side of the pharynx. Opposite the middle con-
strictor muscle they unite with branches of the pneumo-gastric and glosso-
pharyngeal nerves ; and by their union with those nerves the pliaryngeal
plexus is formed. Branches emanating from the plexus are distributed
to the muscles and mucous membrane of the pharynx.
3. UPPER CARDIAC NERVE.
Each of the cervical ganglia of the sympathetic furnishes a cardiac branch,
the three being named respectively the upper, middle and lower cardiac
nerves.
These branches are continued singly, or in connection, to the large
prevertebral centre (cardiac plexus) of the thorax. Their size varies con-
siderably, and where one branch is smaller than common, another will be
found to be increased in size, as if to compensate for the defect. There
are some differences in the disposition of the nerves of the right and left
sides.
The upper cardiac nerve (n. cardiacus superficialis) of the right side
proceeds from two or more branches of the ganglion, with, in some
instances, an offset from the cord connecting the first two ganglia. In its
course down the neck the nerve lies behind the carotid sheath, in contact with
the longus colli muscle ; and it is placed in front of the lower thyroid artery
and the recurrent laryngeal nerve. Entering the thorax, it passes in some
cases before, in others behind the subclavian artery, and is directed along the
innominate artery to the back part of the arch of the aorta, where it ends in
the deep cardiac plexus, a few small filaments continuing also to the front
of the great vessel. Some branches distributed to the thyroid body
accompany the inferior thyroid artery.
In its course downwards the cardiac nerve is repeatedly connected with] other
branches of the sympathetic, and with the pneumo-gastric nerve. Thus about the
middle of the neck it is joined by some filaments from the external laryngeal
UPPER CARDIAC XERVE.
691
nerve; and, rather lower down, by one or more filaments from the trunk of the
pneumo-gastric nerve ; lastly, on entering the chest, it joins with the recurrent
laryngeal.
Fig. 453.
Fig. 453. — CONNECTIONS OF THE CERVICAL AND UPPER DORSAL SYMPATHETIC GANGLIA
AND NERVES ON THE LEFT SIDE.
The full description of this figure will be found at p. 620. The following numbers
refer to the sympathetic ganglia and nerves, and those immediately connected with
them : — 3, pharyngeal plexus ; 8, laryngeal plexus ; 13, pulmonary plexus ; and to
the reader's left, above the pulmonary artery, a part of the cardiac plexus ; 24, superior
cervical ganglion of the sympathetic ; 25, middle cervical ganglion ; 26, inferior cervical
ganglion united with the first dorsal ganglion ; 27, 28, 29, 30, second, third, fourth, and
fifth dorsal ganglia.
Variety. — Instead of passing to the thorax in the manner described, the superior
cardiac nerve may join the cardiac branch furnished from one of the other cer-
vical ganglia. Scarpa describes this as the common disposition of the nerve ;
but Cruveilhier (Anat. Descript., t. iv.) states that he has not in any case
found the cardiac nerves to correspond exactly ^ith the figures of the " Tabula*
Xeurologicae."
692 THE SYMPATHETIC NERVES.
The superficial cardiac nerve of the left side has, while in the neck, the
same course and connections as that of the right side. But within the
chest it follows the left carotid artery to the arch of the aorta, and ends in
some instances in the superficial cardiac plexus, while in others it joins the
deep plexus ; and accordingly it passes either in front of or behind the arch
of the aorta.
4. BRANCHES TO BLOOD-VESSELS.
The nerves which ramify on the arteries (nervi molles) spring from the
front of the ganglion, and twine round the trunk of the carotid artery.
They are prolonged on each branch of the external carotid, and form
slender plexuses upon them.
Communications with other nerves. — From the plexus on the facial artery is derived
the filament which joins the submaxillary ganglion ; and, from that on the middle
meningeal artery, twigs have been described as extending to the otic ganglion, as
well as to the gangliform enlargement of the facial nerve. Lastly, a communication
is established between the plexus on the carotid artery, and the digastric branch of
the facial nerve.
Small ganglia are occasionally found on some of the vascular plexuses,
close to the origin of the vessels with which they are associated. Thus
lingual, temporal, and pharyngeal ganglia have been described ; and besides
these there is a larger body, the ganglion intercaroticum, placed on the
inner side of the angle of division of the common carotid artery. This body,
long known to anatomists as a ganglion, has been stated by Luschka to
have a structure very different from the nervous ganglia in general, and has
been named by him the "glandula intercarotica. "
The ganglion intercaroticum was described by Luschka as presenting principally
a follicular structure, and regarded by him as being of a nature similar to the glan-
dula coccygea, which he had previously discovered. It appears, however, from the
researches of Julius Arnold, that the follicular appearances observed by Luschka, both
in this instance and in the coccygeal gland, were produced by arterial glomeruli seen
in section; and that the ganglion intercaroticum consists of numbers of those glome-
ruli gathered into several larger masses, and of dense plexuses of nerves surrounding
respectively the glomeruli, the masses, and the whole structure. Within those plex-
uses nerve-cells are scattered, but not in very great number. The ganglion is usually
about one-fourth of an inch long ; but, according to Luschka, may be divided into
small separate masses, and thus escape attention, or be supposed to be absent. —
(Luschka, Anat. d. Menschen, vol. i. 1862 ; and Julius Arnold, in Virchow's Archiv.,
June, 1865.)
MIDDLE CERVICAL GANGLION.
The middle ganglion (ganglion thyroideum), much the smallest of the
cervical ganglia, is placed on or near the inferior thyroid artery. It is
usually connected with the fifth and sixth spinal nerves, but in a somewhat
variable manner. It gives off thyroid branches and the middle cardiac
nerve.
THYROID BRANCHES. — From the inner side of the ganglion some twigs
proceed along the inferior thyroid artery to the thyroid body, where they
join the recurrent laryngeal and the external laryngeal nerves. Whilst on
the artery, these branches communicate with the upper cardiac nerve.
THE MIDDLE CARDIAC NERVE (nervus cardiacus profundus v. magnus) of the
right side is prolonged to the chest behind the sheath of the common carotid
artery, and either in front of or behind the subclavian artery. In the
LOWER CEHVICAL GANGLION. 693
chest it lies on the trachea, where it is joined by filaments of the recurrent
laryngeal nerve, and it ends in the right side of the deep cardiac plexus.
While in the neck, the nerve communicates with the upper cardiac nerve
and the recurrent branch of the pueumo-gastric.
On the left side, the middle cardiac nerve enters the chest between the
left carotid and subclavian arteries, and joins the left side of the deep
cardiac plexus.
AVhen the middle cervical ganglion is small, the middle cardiac nerve may be
found to be an offset of the inter-ganglionic cord.
LOWER CERVICAL GANGLION".
The lower or third cervical ganglion is irregular in shape, usually some-
what flattened and round or semiluuar, and is frequently united in part
to the first thoracic ganglion. Placed in a hollow between the transverse
process of the last cervical vertebra and the neck of the first rib, it is con-
cealed by the vertebral artery. It is connected by short communicating
cords with the two lowest cervical nerves. Numerous branches are given
oif from it, among which the largest is the lower cardiac nerve.
THE LOWER CARDIAC NERVE, issuing from the third cervical ganglion or
from the first thoracic, inclines inwards on the right side, behind the sub-
clavian artery, and terminates in the cardiac plexus behind the arch of the
aorta. It communicates with the middle cardiac and recurrent laryngeal
nerves behind the subclavian artery.
On the left side, the lower cardiac often becomes blended with the middle
cardiac nerve, and the cord resulting from their union terminates in the
deep cardiac plexus.
BRANCHES TO BLOOD-VESSELS. — From the lowest cervical and first dorsal
ganglia a few slender branches ascend along the vertebral artery in its
osseous canal, forming a plexus round the vessel by their inter-communica-
tions, and supplying it with offsets. This plexus is connected with the
cervical spinal nerves as far upwards as the fourth.
One or two branches frequently pass from the lower cervical ganglion to
the first dorsal ganglion in front of the subclavian artery, forming loops
round the vessel (ansse Vieussenii), and supplying it with small offsets.
THORACIC PART OF THE GANGLIATED CORD.
In the thorax the gangliated cord is placed towards the side of the spinal
column, in a line passing over the heads of the ribs. It is covered by the
pleura, and crosses the intercostal blood-vessels.
Opposite the head of each rib the cord usually presents a ganglion,
so that there are commonly twelve of these ; but, from, the occasional
coalescence of two, the number varies slightly. The first ganglion when
distinct is larger than the rest, and is of an elongated form ; but it is often
blended with the lower cervical ganglion. The rest are small, generally
oval, but very various in form.
Connection with the spinal nerves. — The branches of connection between
the spinal nerves and the ganglia of the sympathetic are usually two in
number for each ganglion ; one of these generally resembling the spinal
nerve in structure, the other more similar to the sympathetic nerve.
BRANCHES OF THE GANGLIA.
The branches furnished by the first fivt or six ganglia are small, and are
946
THE SYMPATHETIC NERVES.
Fig. 451
THORACIC GAXGLIA. 695
Fig. 451.— DIAGRAMMATIC VIEW OP THE SYMPATHETIC CORD OP THE RIGHT SIDT-, SHOWING
ITS CONNECTIONS WITH THE PRINCIPAL CEREBRO-SPINAL NERVES AND THE MAIN
PREAORTIC PLEXUSES. £
Cerebro-spinal Nerves. — VI, a portion of the sixth cranial nerve as it passes through
the cavernous sinus, receiving two twigs from the carotid plexus of the sympathetic nerve;
0, ophthalmic ganglion connected by a twig with the carotid plexus ; M, connection of the
spheno-palatine ganglion by the Vidian nerve with the carotid plexns ; C, cervical plexus;
Br, brachial plexus ; D 6, sixth intercostal nerve ; D 12, twelfth ; L 3, third lumbar
nerve; S 1, first sacral nerve ; S 3, third ; S 5, fifth ; Cr, anterior crural nerve ; Cr', great
sciatic ; pn, pneumo-gastric nerve in the lower part of the neck ; r, recurrent nerve
winding round the subclaviau artery.
Sympathetic Cord. — c, superior cervical ganglion ; </, second or middle; c", inferior;
from each of these ganglia cardiac nerves (all deep on this side) are seen descending to
the cardiac plexus; d 1, placed immediately below the first dorsal sympathetic ganglion :
d 6, is opposite the sixth; 11, first lumbar ganglion; eg, the terminal or coccygeal
ganglion.
Preaortic and Visceral Plexuses. — pp, pharyngeal, and, lower down, laryngeal
plexus ; p I, posterior pulmonary plexus spreading from the pneumo-gastric on the back
of the right bronchus ; c a, on the aorta, the cardiac plexus, towards which, in addition
to the cardiac nerves from the three cervical sympathetic ganglia, other branches are seen
descending from the pneumo-gastric and recurrent nerves ; c o, right or posterior, and c o',
left or anterior coronary plexus ; o, cesophageal plexus in long meshes on the gullet ; sp,
great splanchnic nerve formed by branches from the fifth, sixth, seventh, eighth, and
ninth dorsal ganglia; +, small splanchnic from the ninth and tenth ; + +, smallest or
third splanchnic from the eleventh : the first and second of these are shown joining the
solar plexus, so; the third descending to the renal plexus, re; connecting branches
between the solar plexus and the pneumo-gastric nerves are also represented ; p n', above
the place where the right pneumo-gastric passes to the lower or posterior surface of the
stomach ; p n", the left distributed on the anterior or upper surface of the cardiac portion
of the organ : from the solar plexus large branches are seen surrounding the arteries of
the cceliac axis, and descending to m s, the superior mesenteric plexus ; opposite to this
is an indication of the suprarenal plexus ; below r e (the renal plexus), the spermatic
plexus is also indicated ; a o, on the front of the aorta, marks the aortic plexus, formed
by nerves descending from the solar and superior mesenteric plexuses and from the lumbar
ganglia ; m i, the inferior mesenteric plexus surrounding the corresponding artery ; h y,
hypogastric plexus placed between the common iliac vessels, connected above with the
aortic plexus, receiving nerves from the lower lumbar ganglia, and dividing below into the
right and left pelvic or inferior hypogastric plexuses ; p I, the right pelvic plexus ; from
this the nerves descending are joined by those from the plexus on the superiorjiemor-
rhoidal vessels, m i', by sympathetic nerves from the sacral ganglia, and by numerous
visceral nerves from the third and fourth sacral spinal nerves, and there are thus formed
the rectal, vesical, and other plexuses, which ramify upon the viscera from behind for-
wards and from below upwards, as towards i r, and v, the rectum and bladder.
distributed in a great measure to the thoracic aorta, the vertebrae, and liga-
ments. Several of these branches enter the posterior pulmonary plexus.
The branches furnished by the lower six or seven ganglia unite into three
cords on each side, which pass down to join plexuses in the abdomen, and
are distinguished as the great, the small, and the smallest splanchnic nerve.
THE GREAT SPLANCHNIC NERVE.
This nerve is formed by the union of small cords (roots) given off by the
thoracic ganglia from the fifth or sixth to the ninth or tenth inclusive. By
careful examination of specimens after immersion in acetic or diluted nitric
acid, small filaments may be traced from the splanchnic roots upwards as
far aa the third ganglion, or even as far as the first (Beck, in the " Philo-
sophical Transactions," Part 2, for 1846).
Gradually augmented by the successive addition of the several roots, the
cord descends obliquely inwards over the bodies of the dorsal vertebrae ;
and, after perforating the crus of the diaphragm at a variable point, termi-
696 THE SYMPATHETIC NEEYES.
Dates in the semilunar ganglion, frequently sending some filaments to the
renal plexus and the suprarenal body.
The splanchnic nerve is remarkable from its white colour and firmness,
which are owing to the preponderance of the spinal nerve-fibres in its
composition.
In the chest the great splanchnic nerve is not unfrequently divided into parts, and
forms a plexus with the small splanchnic nerve. Occasionally also a small ganglion
(ganglion splanchnicum) is formed on it over the last dorsal vertebra, or the last but
one ; and when it presents a plexiform arrangement, several small ganglia have been
observed on its divisions.
In eight instances out of a large number of bodies, Wrisberg observed a fourth
splanchic nerve (nervus splanclmicus supremus). It is described as formed by
offsets from the cardiac nerves, and from the lower cervical as well as some of
the upper thoracic ganglia. (" Observ. Anatom. de Nerv. Viscerum particula
prima," p. 25, sect. 3.)
SMALL SPLANCHNIC NERVE.
The small or second splanchnic nerve springs from the tenth or eleventh
ganglia, or from the neighbouring part of the cord. It passes along with the
preceding nerve, or separately through the diaphragm, and ends in the
coeliac plexus. In the chest this nerve often communicates with the large
splanchnic nerve ; and in some instances it furnishes filaments to the renal
plexus, especially if the lowest splanchnic nerve is very small or wanting.
SMALLEST SPLANCHNIC NERVE.
This nerve (nerv. renalis posterior — Walter) arises from one of the lowest
thoracic ganglia, and communicates sometimes with the nerve last described.
After piercing the diaphragm, it ends in the renal plexus, and in the inferior
part of the coeliac plexus.
LUMBAR PART OF THE GANGLIATED CORD.
In the lumbar region the two gangliated cords approach one another
more nearly than in the thorax. They are placed before the bodies of the
vertebrae, each lying along the inner margin of the psoas muscle ; and that
of the right side is partly covered by the vena cava.
The ganglia are small, and of an oval shape. They are commonly four
in number, but occasionally, when their number is diminished, they are of
larger size.
Connection with spinal nerves. —In consequence of the greater distance at
which the lumbar ganglia are placed from the intervertebral foramina, the
branches of connection with the spinal nerves are longer than in other
parts of the gangliafced cord. There are generally two connecting branches
for each ganglion, but the number is not so uniform as it is in the chest ;
nor are those belonging to any one ganglion connected always with the
same spinal nerve. The connecting branches accompany the lumbar arte-
ries, and, as they cross the bodies of the vertebrae, are covered by the
fibrous bauds which give origin to the larger psoas muscle.
BRANCHES. — The branches of these ganglia are uncertain in their number.
Some join a plexus on the aorta ; others descending go to form the hypo-
gastric plexus. Several filaments are distributed to the vertebrae and the
ligaments connecting them.
SACRAL PART OF THE GANGLIATED CORD.
Over the sacrum the gangliated cord of the sympathetic nerve is much
SACRAL GANGLIA. 69?
diminished in size, and gives but few branches to the viscera. Its position
on the front of the sacrum is along the inner side of the anterior sacral
foramina ; and, like the two series of those foramina, the two cords approach
one another in their progress downwards. The upper end of each is con-
nected with the last lumbar ganglion by a single or a double iuterganglionic
cord ; and at the lower end, they are connected by means of a loop with
a single median ganglion, ganglion impar, placed on the fore part of the
coccyx. The sacral ganglia are usually five in number ; but the variation
both in size and number is more marked in these than in the thoracic
or lumbar ganglia.
Connection with spinal nerves. — From the proximity of the sacral ganglia
to the spinal nerves at their emergence from the foramina, the com-
municating branches are very short : there are usually two for each ganglion,
and these are in some cases connected with different sacral nerves. The
coccygeal nerve communicates with the last sacral, or the coccygeal ganglion.
Branches. — The branches proceeding from the sacral ganglia are much
smaller than those from other ganglia of the cord. They are for the
most part expended on the front of the sacrum, and join the corresponding
branches from the opposite side. Some filaments from one or two of the
first ganglia enter the hypogastric plexus, while others go to form a plexus
on the middle sacral artery. From the loop connecting the two cords on
which the coccygeal ganglion is formed, filaments are given to the coccyx
and the ligaments about it, and to the coccygeal glaud.
COCCYGEAL GLA.ND.
Under this name has been described by Luschka a minute structure,
which has since received the attention of a number of writers. It is
usually, according to Luschka, of the size of a lentil, and sometimes as large
as a small pea ; its colour is reddish grey ; its surface lobulated ; and it
occupies a hollow at the tip of the coccyx, between the tendons attached to
that part. It receives terminal twigs of the middle sacral artery and
minute filaments from the ganglion impar. It consists of an aggregation of
grains or lobules, which in some instances remain separate one from
another. These lobules are principally composed of thick- walled cavities of
vesicular and tubular appearance, described by Luschka and subsequent
writers as closed follicles filled with cellular contents, but recently demon-
strated by Julius Arnold to be clumps of dilated and tortuous small arteries,
with thickened muscular and epithelial coats. Nerve-cells are found scattered
in the stroma of the organ.
The coccygeal gland is a structure evidently of a similar nature to the ganglion
intercaroticum, the principal differences apparently being, that the glomeruli of the
ganglion intercaroticum are produced principally by the convolution and ramification
of arterial twigs, while in the coccygeal gland there is dilation of the branches
and thickening of their walls ; and that the nervous element 'is more developed
in the intercarotid ganglion than in the coccygeal gland. Arnold, with Luschka,
appears inclined to consider both structures as allied iu nature to the suprarenal cap-
sules. According to Arnold, there is always a number of small grape-like appen-
dages on the coccygeal part of the middle sacral artery, microscopic in size, but
similar in nature to the lobules of which the coccygeal gland is composed. (Luschka,
" Der Hirnanhang und die Steissdruse des Menschen." Berlin, 1860. Also "Anat.
d. Menseh./' vol. ii. part 2, p. 187. Julius Arnold in Virchow's " Archiv," March,
1865.)
z z
698 THE SYMPATHETIC NERVES.
B. THE GREAT PLEXUSES OF THE SYMPATHETIC.
Under this head may be included certain large plexuses of nerves placed
further forwards in the visceral cavity than the gangliated cords, and
furnishing branches to the viscera. The principal of these plexuses are the
cardiac, the solar, and the hypogastric with the pelvic plexuses prolonged
from it. They are composed of assemblages of nerves, or of nerves and
ganglia, and from them smaller plexuses are derived.
CARDIAC PLEXUS.
This plexus receives the cardiac branches of the cervical ganglia and those
of the pneumo-gastric nerves, and from it proceed the nerves which supply
the heart, besides some oifsets which contribute to the nervous supply of
the lungs. It lies upon the aorta and pulmonary artery, where these vessels
are in contact, and in its network are distinguished two parts, the superficial
aud the deep cardiac plexuses, the deep plexus being seen behind the vessels,
and the superficial more in front, but both being closely connected. The
branches pass from these plexuses chiefly forward in two bundles, accom-
panying the coronary arteries.
SUPERFICIAL CARDIAC PLEXUS.
The superficial cardiac plexus lies in the concavity of the arch of the
aorta, in front of the right branch of the pulmonary artery. In it the
superficial or first cardiac nerve of the sympathetic of the left side termi-
nates, either wholly or iu part, together with the lower cardiac branch of
the left pneumo-gastric nerve, and in some cases also that of the right
side. In the superficial plexus a small ganglion, the ganglion of Wrisberg,
is frequently found at the point of union of the nerves. Besides ending in
the anterior coronary plexus, the superficial carliac furnishes laterally
filaments along the pulmonary artery to the anterior pulmonary plexus of
the left side.
DEEP CARDIAC PLEXUS.
The deep cardiac plexus, much larger than the superficial one, is placed
behind the arch of the aorta, between it and the end of the trachea, and
above the point of division of the pulmonary artery.
This plexus receives all the cardiac branches of the cervical ganglia of the
sympathetic nerve, except the first or superficial cardiac nerve of the left
side. It likewise receives the cardiac nerves furnished by the vagus and by
the recurrent laryngeal branch of that nerve, with the exception of the
left lower cardiac nerve.
Of the branches from the right side of the plexus, the greater
number descend in front of the right pulmonary artery, and join branches
from the superficial part in the formation of the anterior coronary plexus,
while the rest, passing behind the right pulmonary artery, are distributed
to the right auricle of the heart, and a few filaments are continued
into the posterior coronary plexus.
On the left side, a few branches pass forwards by the side of the ductus
arteriosus to join the superficial cardiac plexus ; but the great majority
end in the posterior coronary plexus.
The deep c.trdiac plexus sends filaments to the anterior pulmonary plexus
on each bide.
SOLAR PLEXUS. 699
CORONARY PLEXUSES. — The anterior coronary plexus, formed at first from the
fibres of the superficial cardiac plexus, passes forwards between the aorta and pul-
monary artery, and, having received an accession of fibres from the deep cardiac
plexus, follows the course of the left or anterior coronary artery.
The posterior coronary plexus, derived chiefly from the left part of the deep car-
diac plexus, but joined by nerves from the right portion of that plexus, surrounding
the branches of the right coronary artery accompany them to the back of the heart.
Nervous filaments ramify in great number under the lining membrane of the
heart. They are not so easily distinguished in man as in some animals. In the
heart of the calf or lamb they are distinctly seen without dissection, running in lines
which cross obliquely the muscular fibres. Remak was the first to observe that these
branches are furnished with small ganglia, both on the surface and in the muscular
substance. (Mailer's " Archiv," 1844.)
SOLAR OR EPIGASTRIC PLEXUS.
The solar or epigastric plexus, which is the largest of the prevertebral
centres, is placed at the upper part of the abdomen, behind the stomach, and
iii front of the aorta and the pillars of the diaphragm. Surrounding the
origin of the coeliac axis and the upper mesenteric artery, it occupies the
interval between the suprarenal bodies, and extends downwards as far as the
pancreas. The plexus consists of nervous cords, with several ganglia of
various sizes connected with them. The large splanchnic nerves on both sides,
and some branches of the pneumo- gastric, terminate in it. The branches
given off from it are very numerous, and accompany the arteries to the
principal viscera of the abdomen, constituting so many secondary plexuses
on the vessels. Thus diaphragmatic, coeliac, renal, mesenteric, and other
plexuses are recognised, which follow the corresponding arteries.
Semilunar ganglia. — The solar plexus contains, as already mentioned,
several ganglia ; and by the presence of these bodies, and their size, it is
distinguished from the other prevertebral plexuses. The two principal
ganglionic masses, named semtlttuor, though they have often little of the
form the name implies, occupy the upper and outer part of the plexus, one
on each side, and are placed close to the suprarenal bodies by the side of
the coeliac and the superior mesenteric arteries. At the upper end, which
is expanded, each ganglion receives the great splanchnic nerve.
DIAPHRAGMATIC PLEXUS. — The nerves (inferior diaphragmatic) composing this
plexus are derived from the upper part of the semilunar ganglion, and are larger on
the right than on the left side. Accompanying the arteries along the lower surface
of the diaphragm, the nerves sink into the substance of the muscle. They furnish
some filaments to the suprarenal body, and join with the spinal phrenic nerves.
At the right side, on the under surface of the diaphragm, and near the suprarenal
body, there is a small ganglion, ganglion diaphragmatic um, which marks the junc-
tion between the phrenic nerves of the spinal and sympathetic systems. From this
small ganglion filaments are distributed to the vena cava, the suprarenal body, and
the hepatic plexus. On the left side the ganglion is wanting, but some filaments are
prolonged to the hepatic plexus.
SUPRARENAL PLEXUS.— The suprarenal nerves issue from the solar plexus and the
outer part of the semilunar ganglion, a few filaments being added from the diaphrag-
matic nerve. They are short, but numerous in comparison with the size of the body
which they supply : they enter the upper and inner parts of the suprarenal cap-
sule. These nerves are continuous below with the renal plexus. The plexus is
joined by branches from one of the splanchnic nerves, and presents a ganglion
(g<ingl. splanchnico-suprarenale}, where it is connected with those branches. The.
plexus and ganglion are smaller on the left than on the right side.
700
THE SYMPATHETIC NERVES.
Fig. 455.
ABDOMINAL PLEXUSES. 701
Fig. 455. — DIAGRAMMATIC VIEW OF THE SYMPATHETIC CORD OF THE RIGHT SIDE, WITH
ITS PRINCIPAL GANGLIA, PLEXUSES, AND NERVES.
This figure is repeated in illustration of the sympathetic uerves in the lower half of the
body.
c, superior cervical ganglion ; c', second or middle ; c", inferior : from each of these
ganglia cardiac nerves (deep on this side) are seen descending to the cardiac plexus ; dl,
placed immediately below the first dorsal sympathetic ganglion ; d 6, is opposite the
sixth ; 1 1, first lumbar ganglion ; eg, the terminal or coccygeal ganglion ; pp, pharyugeal,
aud, lower down, laryngeal plexus ; pi, posterior pulmonary plexus spreading from the
pneumo-gastric on the back of the right bronchus ; ca, on the aorta, the cardiac plexus,
towards which, in addition to the cardiac nerves from the three cervical sympathetic
ganglia, other branches are seen descending from the pneumogastricand recurrent nerves ;
co, right or posterior, and co', left or anterior coronary plexus ; o, ossophageal plexus in
long meshes on the gullet ; sp, great splanchnic nerve formed by branches from the fifth,
sixth, seventh, eighth, and ninth dorsal ganglia ; +, small splanchnic from the ninth
and tenth ; + +, smallest or third splanchnic from the eleventh : the fir^t and second of
these are shown joining the solar plexus, so; the third descending to the renal plexus, re;
connecting branches between the solar plexus and the pneumo-gastric nerves are also re-
presented ; pn', above the place where the right pneumo-gastric passes to the lower or
posterior surface of the stomach ; pn", the left distributed on the anterior or upper surface
of the cardiac portion of the organ : from the solar plexus large branches are seen sur-
rounding the arteries of the cccliac axis, and descending to ins, the superior mesenteric
plexus ; opposite to this is an indication of the suprarenal plexus ; below re (the renal
plexus), the spermatic plexus is also indicated ; ao, on the front of the aorta, marks the
aortic plexus, formed by nerves descending from the solar and superior mesenteric plexuses
and from the lumbar ganglia ; mi, the inferior mesenteric plexus surrounding the cor-
responding art* ry ; hy, hypogastric plexus placed between the common iliac vessels,
connected above with the aortic plexus, receiving nerves from the lower lumbar ganglia,
and dividing below into the right and left pelvic or inferior hypogastric plexuses ; pi, the
right pelvic plexus ; from this the nerves descending are joined by those from the plexus
on the superior heinorrhoidal vessel, mi', by sympathetic nerves from the sacral ganglia,
and by numerous visceral nerves from the third and fourth sacral spinal nerves, and there
are thus formed the rectal, vesical, and other plexuses, which ramify upon the viscera from
behind forwards and from below upwards, as towards ir, and v, the i\ctum and bladder.
RENAL PLEXUS. — The nerves forming the renal plexus, fifteen or twenty in number,
emanate for the most part from the outer part of the semilunar ganglion ; but
some are added from the solar plexus and the aortic plexus. Moreover, filaments from
the smallest splanchnic nerve, and occasionally from the other splanchnic nerves,
terminate in the renal plexus. In their course along the renal artery, ganglia of dif-
ferent sizes are formed on these nerves. Lastly, dividing with the branching of the
vessel, the nerves follow the renal arteries into the substance of the kidney. On the
right side some filaments are furnished to the vena cava, behind which the plexus
passes with the renal artery ; and others go to form the spermatic plexus.
SPERMATIC PLEXUS. — This small plexus commences in the renal, but receives in its
course along the spermatic artery an accession from the aortic plexus. Continuing
downwards to the testis, the spermatic nerves are connected with others which
accompany the vas defcrens and its artery from the pelvis.
In the female, the plexus, like the artery, is distributed to the ovary and the
uterus.
CCELIAC PLEXUS. — This plexus is of large size, and is derived from the fore part
of the great epigastric plexus. It surrounds the coeliac axis in a kind of membra-
nous sheath, and subdivides, with the artery, into coronary, hepatic, and splenic
plexuses, the branches of which form communications corresponding with the arches
of arterial anastomosis. The plexus receives offsets from one or more of the
splanchnic nerves, and on the left side a branch from the pneumo-gastric nerve is
continued into it. (Swan.)
The coronary plexus is placed with its artery along the small curvature of the
stomach, and unites with the nerves which accompany the pyloric artery, as well as
with branches of the pneumo-gastric nerves. The nerves of this plexus enter the
coats of the stomach, after running a short distance beneath the peritoneum.
The hepatic plexus, the largest of the three divisions of the coeliac plexus, ascends
with the hepatic vessels and the bile-duct, and; entering the substance of the liver,
702 THE SYMPATHETIC NERVES.
ramifies on the branches of the vena portee and the hepatic artery. Offsets from the
left pneu mo -gastric and diaphragmatic nerves join the hepatic plexus at the left
side of the vessels. From this plexus filaments are furnished to the right supra-
renal plexus, as well as other secondary plexuses which follow the branches of the
hepatic artery. Thus there is a cystic plexus to the gall-bladder; and there are
pylorie, gastro-epiploic, and gastro- duodenal plexuses, which unite with coronary,
splenic, and mesenteric nerves.
The splenic plexus, continued on the splenic artery and its branches into the
substance of the spleen, is reinforced at its beginning by branches from the left semi-
lunar ganglion, and by a filament from the right vagus nerve. It furnishes the left
gastro-epiploic and pancreatic plexuses, which course along the corresponding branches
of the splenic artery, and, like the vessals, are distributed to the stomach and
pancreas.
SUPERIOR MESENTERIC PLEXUS. — The plexus accompanying the superior mesenteric
artery, whiter in colour and firmer than either of the preceding offsets of the solar
plexus, envelopes the artery in a membraniform sheath, and receives a prolongation
from the junction of the right pneumo-gastric nerve with the cceliac plexus. Near
the root of the artery, ganglionic masses (gangl. ineseraica) occur in connection with
the nerves of this plexus.
The offsets of the plexus are in name and distribution the same as the vessels.
In their progress to the intestine some of the nerves quit the arteries which first sup-
ported them, and are directed forwards in the intervals between the vessels. As they
proceed, they divide, and unite with lateral branches, like the arteries, but without
the same regularity : they finally pass upon the intestine along the line of attachment
of the mesentery.
THE AORTIC PLEXUS.
The aortic or intermesentcric plexus, placed along the abdominal aorta,
and occupying the interval between the origin of the superior and inferior
mesenteric arteries, consists, for the most part, of two lateral portions,
connected with the ^emilimar ganglia and renal plexuse?, which are extended
on the sides of the aorta, and which meet in several larger communicating
branches over the middle of that vessel. It is joined by branches from some
of the lumbar ganglia, and presents not unfrequently one or more distinct
ganglionic enlargements towards its centre.
The aortic plexus furnishes the inferior mesenteric plexus and part of the
spermatic, gives some filaments to the lower vena cava, and ends below in
the hypogastric plexus.
INFERIOR MESENTERIC PLEXUS. — This plexus is derived principally from the left
lateral part of the aortic plexus, and closely surrounds with a network the inferior
meeenteric artery. It distributes nerves to the left or descending part and the
sigmoid flexure of the colon, and assists in supplying the rectum. The nerves of this
plexus, like those of the superior mesenteric plexus, are firm in texture, and of a
whitish colour.
The highest branches (those on the left colic artery) are connected with the last
branches (middle colic) of the superior mesenteric plexus, while others in the pelvis
unite with offsets derived from the pelvic plexus.
HYPOGASTRIC PLEXUS.
The hypogastric plexus, the assemblage of nerves destined for the supply
of the viscera of the pelvis, lies invested in a sheath of dense connective
tissue, in the interval between the tyvo common iliac arteries. It is formed
by eight or ten nerves on each side, which descend from the aortic plexus,
receiving considerable branches from the lumbar ganglia, and, after crossing
the common iliac artery, interlace in tho form of a flat plexiform mass
placed in front of the lowest lumbar vertebra. The plexus contains no
HYPOGASTRIC AND PELVIC PLEXUSES. 703
distinct ganglia. At the lower end it divides into two parts, which are
directed forwards, one to each side of the pelvic viscera, and form the pelvic
plexuses.
PELVIC PLEXUS.
The pelvic or inferior hypogastric plexuses, one on each side, are placed in
the lower part of the pelvic cavity by the side of the rectum, and of the
vagina in the female. The nerves, prolonged from the hypogastric plexus,
enter into repeated communications as they descend, and form at the points
of connection small knots, which contain a little gangliouic matter. After
descending some way, they become united with branches of the spinal
nerves, as well as with a few offsets of the sacral ganglia, and the union of
all constitutes the pelvic plexus. The spinal branches, which enter into
the plexus, are furnished from the third and fourth sacral nerves, especially
the third ; and filaments are likewise added from the first and second
sacral nerves. Small ganglia are formed at the places of union of the spinal
nerves, as well as elsewhere in the plexus (plexus gangliosus — Tiedemann).
From the plexus so constituted numerous nerves are distributed to the
pelvic viscera. They correspond with the branches of the internal iliac
artery, and vary with the sex ; thus, besides haemorrhoidal and vesical
nerves, which are common to both sexes, there are nerves special to
each : — namely in the male, for the prostate, vesicula seminalis, and vas
deferens ; in the female, for the vagina, uterus, ovary, and Fallopian tube.
The nerves distributed to the urinary bladder and the vagina contain a
larger proportion of spinal nerves than those furnished to the other pelvic
viscera.
INFERIOR ILEMORRHOIDAL NERVES. — These slender nerves proceed
from the back part of the pelvic plexus. They join with the nerves
(superior hsemorrhoidal) which descend with the inferior mesenteric artery,
and penetrate the coats of the rectum.
VESICAL PLEXUS. — The nerves of the urinary bladder are very numerous.
They are directed from the anterior part of the pelvic plexus to the side
and lower part of the bladder. At first, these nerves accompany the vesical
blood-vessels, but afterwards they leave the vessels, and subdivide into
minute branches before perforating the muscular coat of the organ.
Secondary plexuses are given in the male to the ras deferens and the
vesicula seminalis.
The nerves of the vas deferens ramify round that tube, and communicate
in the spermatic cord with the nerves of the spermatic plexus. Those
furnished to the vesicula seminalis form an interlacement on the vesicula,
and some branches penetrate its substance. Other filaments from the
prostatic nerves reach the same structure.
PROSTATIC PLEXUS. — The nerves of this plexus are of considerable size,
and pass onwards between the prostate gland and the levator ani. Some are
furnished to the prostate and to the vesicula seminalis ; and the plexus is
then continued forwards to supply the erectile substance of the penis, where
its nerves are named " cavernous."
Cavernous nerves of the penis. — These are very slender, and difficult to
dissect. Continuing from, the prostatic plexus they pass onwards, beneath
the arch of the pubes, and through the muscular structure connected with
the membranous part of the urethra, to the dorsum of the penis. At ths
704 THE SYMPATHETIC NERVES.
anterior margin of the levator ani muscle the cavernous nerves are joined
by some short filaments from the pudic nerve. After distributing twigs to
the forepart of the prostate, these nerves divide into branches for the erectile
substance of the penis, as follows : —
Small cavernous nerves (Mtiller), which perforate the fibrous covering of
the corpus cavernosum near the root of the penis, and end in the erectile
substance.
The large cavernous nerve, which extends forward on the dorsum of the
penis, and dividing, gives filaments that penetrate the corpus cavernosum,
and pass with or near the cavernous artery (art. profunda penis). As it
continues onwards, this nerve joins with the dorsal branch of the pudic
nerve about the middle of the penis, and is distributed to the corpus
cavernosum. Branches from, the foregoing nerves reach the corpus spongi-
osum urethrse. (Miiller, " Ueber die organischen Nerven der erectilen
marinlichen Geschlechtsorgane," <fec. Berlin, 1836.)
NERVES OF THE OVARY. — The ovary is supplied chiefly from the plexus
prolonged on the ovarian artery from the abdomen ; but it receives another
offset from the uterine nerves.
VAGINAL PLEXUS. — The nerves furnished to the vagina leave the lower
part of the pelvic plexus — that part with which the spinal nerves are more
particularly combined. They are distributed to the vagina without pre-
viously entering into a plexiform arrangement ; and they end in the erectile
tissue on the lower and anterior part, and in the mucous membrane.
NERVES OF THE UTERUS. —These nerves are given more immediately
from the lateral fasciculus prolonged to the pelvic plexus from the hypo-
gastric plexus, above the point of connection with the sacral nerves.
Separating opposite the neck of the uterus, they are directed upwards with
the blood-vessels along the side of this organ, between the layers of its
broad ligament. Some very slender filaments form round the arteries a
plexus, in which minute ganglia are found scattered at intervals, and these
nerves continue their course in the substance of the organ in connection
with the blood-vessels. But the larger part of the nerves soon leave the
vessels ; and after dividing repeatedly, without communicating with each
other and without forming any gangliform enlargements, sink into the sub-
stance of the uterus, penetrating for the most part its neck and the lower
part of its body. One branch, continued directly from the common hypo-
gastric plexus, reaches the body of the uterus above the rest ; and a nerve
from the same source ascends to the Fallopian tube. Lastly, the ftindus of
the uterus often receives a branch from the ovarian nerve. (Fr. Tiede-
mann, Tab. Nerv. Uteri, Heidelberg, 1822 ; Robert Lee, in Phil. Trans.,
1841, 1842, 1846, and 1849; and Snow Beck, in Phil. Trans., 1846,
part ii.)
The nerves of the gravid uterus have been frequently investigated,
with a view to discover if they become enlarged along with the increase
in size of the organ. It is ascertained that the increase which takes place
is confined, for the most part, to thickening of the fibrous envelopes of
the nerves ; but it appears also, from the researches of Kilian, that fibres
furnished with a medullary sheath, which in the unimpregnated state of the
uterus lose that sheath as they proceed to their distribution, in the im-
pregnated condition of the uterus continue to be surrounded with it as
they run between the muscular fibres. (Farre, in Supplement of Cyclopaedia
of Anat. and Phys., " Uterus and Appendages.")
ORGANS OF THE SENSES. THE EYE. 705
IY. ORGANS OF THE SENSES.
In this place it is intended to describe the organs of sight, hearing and
smelling, which, considered with reference to their anatomy and develop-
ment, are regarded as the higher organs of special sense. The description
of the organ of touch is given along with the skin in the histological part
of the work, and that of the organ of taste along with the descriptive
anatomy of the digestive system.
THE EYE.
The organ of vision, strictly speaking, consists only of the ball or globe
of the eye, a spheroidal structure enclosed by strong membranous coverings,
receiving the optic nerve posteriorly, and containing the sensitive termina-
tions of that nerve, together with a series of transparent media, which con-
stitute an optical instrument of variable focus, through which the rays of light
are transmitted to the sensitive part, and so brought into focus as to form
upon it a distinct inverted image of the objects from which they proceed.
Eut there are likewise various structures external to the eyeball which con-
tribute to the production of perfect vision, such as the straight and oblique
muscles by which the eyeball is moved in different directions, and the various
supporting and protective structures known as appendages of the eye (tuta-
mina oculi), including the eyebrows, eyelids, and conjunctiva, and the lachry-
mal apparatus.
APPENDAGES OP THE EYE.
THE EYELII>S AND CONJUNCTIVA.
The eyelids (palpebrse) are moveable folds of integument, strengthened
toward their margins by a thin lamina of cartilage. The mucous membrane,
which lines their inner surface, and which is reflected thence in the form of
a pellucid covering on the surface of the eyeball, is named membrana con-
junctiva.
The upper lid is larger and more moveable than the lower : the trans-
parent part of the globe is covered by it when the eye is closed ; and the eye
is opened chiefly by the elevation of this lid by a muscle (levator palpebrse)
devoted exclusively to this purpose. The eyelids are joined at the outer and
inner angles (canthi) of the eye. The interval between the angles, fissura
palpebrarum; varies in length in different persons, and, according to its
extent, the size of the globe being nearly the same, gives the appearance of
a larger or a smaller eye. The greater part of the edge of each eyelid is flat-
tened, but towards the inner angle it is rounded off for a short space, at the
same time that it somewhat changes its direction ; and, where the two differ-
ently formed parts join, there exists on each lid a slight conical elevation —
papitta lachrymalis, the apex of which is pierced by the aperture or punctum
of the corresponding lachrymal canalicule.
In the greater part of their extent the lids are applied to the surface of the
eyeball ; but at the inner canthus, opposite the puncta lachrymalia, there
intervenes a vertical fold of conjunctiva, the plica semilunaris, resting on
the eyeball ; while, occupying the recess of the angle internal to the border
of this fold, is a spongy-looking reddish elevation, formed by a group of
3 A
706
THE EYE.
glandular follicles, and named the caruncula lachrymalis. The plica
semilunaris is the rudiment of the third eyelid (rneinbrana nictitans) found
in some animals.
Structure of the lids. — The skiu covering the eyelids is thin and delicate;
and at the line of the eyelashes, altered in its character, it joins the conjunc-
tival mucous membrane which lines the inner surface of the lids. Beneath
the skin, and between it and the conjunctiva, the following structures are
successively met with, viz. : — The fibres of the orbicularis muscle ; loose
connective tissue ; the tarsal cartilages, together with a thin fibrous mem-
brane, the palpebral ligament, which attaches them to the margin of the
orbit ; and, finally, the Meibomian glands. In the upper eyelid there is, in
addition, the insertion of the levator palpebrse superioris, in the form of a
fibrous expansion fixed, to the anterior surface of the tarsal cartilage.
Fig. 456.
Fig. 456. — VERTICAL SECTION OF THE LEFT ORBIT AND ITS CONTENTS.
The section has been carried through the middle of the optic foramen and optic nerve
obliquely as far as the back of the eyeball, and thence forward through the eyeball,
eyelids, &c., in an antero-posterior direction, a, the frontal bone; 6, the superior
maxillary bone; c, the eyebrow with the orbicularis palpebrarum, integument, &c. ,
divided ; d, the upper, and d, the lower eyelid, partially open, showing the section of the
tarsal cartilages and other component parts, the eyelashes, &c. ; e, e, the reflection of
the conjunctiva from the upper and lower eyelids to the surface of the eyeball ; /, the
levator palpebraa superioris muscle; <?, the upper, #', the lower rectus muscle; h, the
inferior oblique muscle divided ; 1, 1, the optic nerve divided in its sheath ; 2, the
cornea ; 2', the sclerotic ; 3, the aqueous chamber ; 4, the crystalline lens ; 5, the
centre of the vitreous humour.
The fibres of the orbicularis muscle are closely adherent to the skin by fine
connective tissue, entirely devoid of fat. A marginal fasciculus of its fibres
has been found within the line of the eyelashes, separated by the bulbs of
the lashes from the other fibres, and constituting the ciliary muscle of Riolan.
The fibres of the orbicular muscle, while adherent to the skin, glide loosely
on the tarsal cartilages.
The tarsal cartilages (tarsi) are two thin elongated plates of cartilages of
the yellow kind placed one in each lid, and serving to give shape and firm-
ness to those parts. The upper cartilage, the larger, is half oval in form,
THE EYELIDS AND CONJUNCTIVA.
707
being broader near the centre and narrowing towards the angles of the lids.
The lower is thinner, much narrower, and more nearly of an uniform breadth
throughout. The free or ciliary edge of the cartilages, which is straight, is
thicker than any other part. At the inner canthus the cartilages are fixed
by the fibrous slips of the tendo palpebrarum (p. 172) ; and at the outer
angle they are attached to the malar bone by a fibrous band belonging to the
palpebral ligament, and named the external tarsal ligament.
The palpebral ligament is a fibrous membrane placed beneath the orbicularis
muscle, attached peripherally to the margin of the orbit, and internally to
the tarsal cartilages near the inner free edge. The membrane is thickest at
the outer part of the orbit.
Meibomian glands. — On the ocular surface of each lid are seen from twenty
to thirty parallel vertical lines of yellow granules, lying immediately under
the conjunctiva! mucous membrane. They are compound sebacious follicles,
Fig. 457.
Fig. 457. — MEIBOMIAN GLANDS,
LACHRYMAL GLAND, &c., AS SKEN
FROM THE DEEP SURFACE OF THE
EYELIDS OF THE LEFT SIDE.
a, palpehral conjunctiva ; 1,
lachrymal gland ; 2, openings of
seven or eight glandular ducts ; 3,
upper and lower puncta lachry-
inalia ; 6, 6, shut ends of the
upper and lower Meihomian glands,
of which the openings are indicated
along the margins of the eyelids.
embedded in grooves at the
back of the tar»al cartilages ;
and they open on the free
margin of the lids by minute
orifices, generally as many in
number as the lines of follicles
themselves. These glands consist of nearly straight excretory tubes, each
of which is closed at the end, and has numerous small coecal appendages
projecting from its sides. The tubes are lined by mucous membrane, oil
the surface of which is a layer of scaly or pavement epithelium cells.
According to Heinrich Miiller there is likewise a layer of unstriped muscular fibre
contained in each eyelid ; that of the upper lid arising from the under surface of the
levator palpebrse, that of the lower lid arising from the neighbourhood of the inferior
oblique muscle, and each being inserted near the margin of the tarsal cartilage. It
may also be mentioned in this place that the same writer describes a layer of unstriped
muscle crossing the spheno-maxillary fissure, corresponding to a more largely developed
layer found in the extensive aponeurotic part of the orbital wall of various mammalia.
This set of fibres has been more particularly described by Turner (H. Miiller, in
Zeitschr. f. Wiss. Zool. 1858, p. 541; W. Turner, in Nat. Hist. Eev. 1862, p. 106).
The eyelashes (cilia) are strong short curved hsirs, arranged in two or
more rows along the margin of the lids, at the line of uni >n between the
skin and the conjunctival mucous membrane. The lashes of the upper lid,
more numerous and longer than the lower, have the convexity of their curve
directed downwards and forwards ; whilst those of the lower lid are arched
in the opposite direction. Near the inner canthus these hairs are weaker
and more scattered.
3 A 2
708 THE EYE.
Structure of the conjunctiva. — The conjunctiva consists of the palpebral
part, along with which may be grouped the plica semilunaris and caruncula
lachrymalis, and of the ocular part or conjunctiva bulbi, in which may be
distinguished the sclerotic and corneal portions : each of these several parts
presents peculiar and distinctive characters. The epithelium is stratified and
thick ; the cells of the superficial strata scaly, delicate, and each with a
distinct nucleus.
The palpebral portion of the conjunctiva is opaque and red, is thicker and
more vascular than auy other part of the membrane, and presents numerous
fine papillae freely supplied with nerves. At the margins of the lids
the palpebral conjunctiva enters the ducts of the Meibomian glands ;
through the pun eta lachrymalia it passes into the canaliculi, and is con-
tinuous with the lining membrane of the lachrymal sac ; and it is prolonged
into the orifices of the ducts of the lachrymal gland.
The sclerotic portion of the conjunctiva, changing its character at the line
of reflection from the eyelids, becomes thinner, and loses its papillary
structure : it is loosely connected to the eyeball by submucous tissue. It is
also transparent and nearly colourless, but a few scattered branches of blood-
vessels are generally visible on it in the healthy condition, and under the
influence of inflammatory congestion a copious network of vessels very irre-
gularly disposed comes into view. This network is derived from the palpebral
and lachrymal arteries. It may be easily made to glide loosely on the sur-
face of the eyeball by pressing the eyelid against it. But another set of
vessels likewise exists on the surface of the sclerotic, and may be brought
into view by congestion. The position of this set is entirely sub-conjunc-
tival, adherent to the sclerotic coat ; they are less tortuous than the conjunc-
tival set, and are derived from the muscular and anterior ciliary branches of
the ophthalmic artery : they remain immoveable on pressure of the eyelid.
They dip into the sclerotic near the cornea, and appear to unite with a more
deeply connected minute network disposed in closely set straight lines,
radiating from the margin of the cornea, and the gorged condition of which
is well known to ophthalmic surgeons as characteristic of sclerotitis.
The corneal conjunctiva consists almost entirely of epithelium, any under-
lying membrane being extremely thin, transparent, and adherent to the
anterior elastic layer of the cornea, in connection with which it will be again
referred to. Vessels lie between it and the cornea, and form a circle of
anastomotic capillary loops around the circumference. This plexus of
vessels extends farther inwards in the foetus.
A well developed network of lymphatics exists throughout the sclerotic and palpebral
portions of the conjunctiva ; but at the margin of the cornea a sudden diminution
takes place in the size of the meshes and diameter of the vessels. Of the network
referred to, only a narrow circle ~th of an inch in diameter exists on the corneal
conjunctiva, and this circle has a well defined inner margin within which no lym-
phatics exist (Teichmann).
The nerves in the membrane, as far as the cornea, seem to have the same arrange-
ment as in the skin in general.
In the submucous tissue of the eyelids there are small follicular glands spread over
the whole surface of the conjunctiva palpebrarum, and in the vicinity of the reflection
of the conjunctiva upon the eyeball a set of larger more complex glands of a racemose
structure, somewhat similar to that of the lachrymal gland (Sappey, C. aud W.
Krause).
Closed follicles have also been observed in the conjunctiva by Bruch, and, after
him, by other observers.
LACHRYMAL GLANDS AND CANALS. 709
THE LACHRYMAL APPARATUS.
The parts which constitute the lachrymal apparatus are the following,
viz. : — The gland by \\hich the tears are secreted, situated at the upper and
outer side of the orbit, together with its excretory ducts ; the two canals
into which the fluid is received near the inner angle ; and the sac wuh the
nasal duct continued from it, through which the teard pass into the inferior
meat us of the nose.
The lachrymal gland, an oblong flattened body, about the size of a small
almond, is placed in the upper and outer part of the orbit, a little behind
the anterior margin. The upper surface of the gland, convex, is lodged in a
slight depression in the orbital plate of the frontal bone, to the periosteum
of which it adheres by fibrous bands ; the lower surface is adapted to the
convexity of the eyeball, and is in contact with the upper and the outer
recti muscles. The fore part of the gland, separated from the rest by a
slight depression, and sometimes described as a second lobe, or as a distinct
gland, is closely adherent to the back of the upper eyelid, and is covered on
the ocular surface only by a reflection of the conjunctiva. The glandular
ducts, usually from six to eight in number, are very small, and emerge from
the thinner portion of the gland. After running obliquely under the mucous
membrane, and separating at the same time from each other, they open in a
row by separate orifices, the greater number in the fold above the outer
cauthus, and two of them (Hyrtl) in the fold below.
Fig. 458.— FRONT OP THE LEFT EYELIDS, p. .„_
WITH THE LACHRYMAL CANALS AND NA- *>'
SAL DUCT EXPOSED.
1,1, upper and lower lachrymal canals,
showing towards the eyelids the narrow
bent portions and the puncta lachrymal ia ;
2, lachrymal sac ; 3, the lower parjb of the
uasal duct ; 4, plica semilunaris ; 5, ca-
runcula lachrymalis.
Lachrymal canals. — On the mar-
gin of each lid, near the inuer
angle, and in front of the fold of
membrane called plica semilunaris,
is a small elevation (papilla lachry-
malis), already described. Each
papilla is perforated by a small
aperture, punctum lachrymale ; and
at these apertures commence two small canals, canaliculi, which convey
the tears from the eye to the lachrymal sac. The upper canal is rather
the smaller and longer of the two : it first ascends from the punctum ; then
makes a sudden bend, and is directed inwards and downwards to join the
lachrymal sac. The lower canal descends from the corresponding punctum ;
and soon changing its direction like the upper one, takes a nearly horizontal
course inwards. Both canals are dilated where they are bent. In some
cases they unite near the end to form a short common trunk ; more
commonly they open separately, but close together, into the sac.
The lachrymal sac and nasal duct constitute together the passage by which
the tears are conveyed from the lachrymal canals to the cavity of the nose.
710 THE EYE.
The lachrymal sac, the upper dilated portion of the passage, is situated at
the side of the nose, near the inner canthus of the eye, and lies embedded
in a deep groove in the lachrymal and upper maxillary bones. It is of an oval
form ; the upper end closed and rounded, and the lower end gradually
narrowiug somewhat into the nasal duct. On the outer side, and a little in
front, it receives the lachrymal canals ; and here it is covered by the tendo
palpebrarum, and by some of the inner fibres of the orbicular muscle of the
lids; while on its inner or posterior. surface the tensor tarsi muscle is placed.
The sac is composed of fibrous and elastic tissues, adhering closely to the
bones above mentioned, and strengthened by fibrous processes sent from the
tendo palpebrarum, which crosses a little above its middle. The inner sur-
face is lined by a reddish mucous membrane, which is continuous through
the canaliculi with the conjunctiva, and through the nasal duct with the
mucous membrane of the nose.
The nasal duct (ductus ad nasum), about six or seven lines in length,
grooving the upper maxillary bone, descends to the fore part of the lower
meatus of the nose, the osseous canal being completed by the ungual and
lower turbiuated bones. A tube of fibrous membrane, continuous with the
lachrymal sac, adheres to the parietes of this canal, and is lined by mucous
membrane, which, at the opening into the nose, is often arranged in the
form of an imperfect valve. The nasal duct is rather narrower in the middle
than at either end ; its direction is not quite vertical, but inclined slightly
outwards and backwards.
The mucous membrane in the canaliculi possesses a laminar epithelium,
but in the nasal sac and duct a ciliated epithelium as in the nose.
Various valves have been described in connection with the lachrymal sac and canals.
One, the valve of Hasner, is formed by the mucous membrane of the nose overhanging
the inferior orifice of the nasal duct, and has had imputed to it the function of pre-
venting entrance of foreign matters in violent expiratory movements; but the
disposition of the mucous membrane at this orifice appears to be subject to some
variation. Another fold, the valve of Huschke, placed at the deep orifice of the canali-
culi, is supposed by some to prevent the return of the tears from the sac into those
tubes, but by others, it is declared to be inconstant, and insufficient, even when found,
to close the orifice. A third fold, the valve of Foltz, is described as forming a projection
inwards on one side of the vertical part of each canaliculus, near the punctual
lachrymale, and as being sufficient to close the tube when it is flattened by the
pressure of the fibres of the orbicularis and tensor tarsi muscles as in winking. The
experiments of Foltz on rabbits go to prove that the punctum lachrymale having been
turned backwards towards the eye in winking, and the canaliculus being compressed
by the muscles, as soon as the pressure is removed the canaliculus resumes its open
form, and so sucks in tears which by the next compression in winking are forced
onwards into the lachrymal sac ; and also, that when the muscles are paralysed, the
canaliculi cease to carry away the tears. See review of Foltz 's paper in Dublin
Quarterly Journal, Feby. 1863; also, Hyrtl, Topogr. Anatomic.
THE GLOBE OF THE EYE.
The globe or ball of the eye is a composite structure of an irregularly
spheroidal form, placed in the fore part of the orbital cavity, and receiving
the thick stem of the optic nerve behind. The recti and obliqui muscles
closely surround the greater part of the eyeball, and are capable of changing
its position within certain limits : the lids, with the plica semilunaris and
caruncle, are in contact with its covering of conjunctiva in front ; and
behind it is supported by a quantity of loose fat and connective tissue.
THE EYEBALL. THE SCLEFxOTIC COAT. 711
The eyeball, when viewed in profile, is found to be composed of segments
of two spheres, of which the anterior is the smaller and more prominent :
the segment of the larger posterior opaque sphere corresponds with the limit
of the sclerotic coat, and the translucent portion of the smaller sphere with
that of the cornea.
From before backwards the ball measures about nine-tenths of an inch,
and its transverse diameter exceeds this measurement by about a line.
Except when directed towards near objects, the axes of the eyes are nearly
parallel ; the optic nerves, on the contrary, diverge considerably from one
another, and each nerve enters the corresponding eye about a tenth of an
inch to the inner or nasal side of the axis of the globe.
The eyeball is composed of several investing membranes, concentrically
arranged, and of certain fluid and solid paits contained within them. The
membranes are three in number, with the following designations and general
structure : — An external fibrous covering, named sclerotic and cornea ; a
middle vascular, pigmentary, and in part also muscular membrane, the choroid
and the iris ; and an iuternal nervous stratum, the retina. The enclosed
refracting media, three in number, are the aqueous humour, the vitreous body,
and the lens with its capsule.
Around the eyeball there is an adventitious tunic of fascia, tunica
vaginalis oculij or capsule of Tenon, which is perforated by the tendons of
the recti and obliqui muscles, and connected with the sclerotic by merely the
most delicate connective tissue. This capsule separates the eye-ball from the
orbital fat, and enables it to glide freely in its movements. (See, for details,
Richet, Traite d'Anatomie Medico-Chirurgicale ; and O'Ferrall, in Dublin
Quart. Journ. Med. Science, July, 1841.)
EXTERNAL COAT OF THE EYEBALL.
The external investing membrane, which forms a complete covering for the
ball, consists of two parts of different appearance and structure. Of these
the hinder part, much the largest, is opaque and densely fibrous, and is
named the sclerotic coat, while the anterior smaller segment is transparent,
and is named the cornea.
THE SCLEROTIC COAT.
The sclerotic (cornea opaca), the tunic of the eye on which the mainte-
nance of the form of the greater part of the organ chiefly depends, is a
strong, opaque, unyielding, fibrous structure. The membrane covers about
five-sixths of the eye-ball, and is pierced behind by the optic nerve. The
outer surface is white and smooth, except where the tendons of the recti and
obliqui muscles are inserted into it. The inner surface is of a light brown
colour, and rough from the presence of a delicate connective tissue (membrana
fusca), through which branches of the ciliary vessels and nerves cross
obliquely. The sclerotic is thickest at the back part of the eye, and thinnest
at about a quarter of an inch from the cornea : at the junction with the
cornea, it is again somewhat thickened. The optic nerve pierces this coat
about one-tenth of an inch internal to the axis of the ball, and the opening
is somewhat smaller at the inner than at the outer surface of the coat. The
fibrous sheath of the nerve, together with the membranous processes which
separate the funiculi of its fibres, blend with the sclerotic at the margin of
the aperture : in consequence of this arrangement, when the neive is cut off
712
THE EYE.
close to the eye-ball, the funiculi are seen to enter by a group of pores ; and
to the part of the sclerotic thus perforated the name of lamina cribtosa is
sometimes given. Around this cribrous opening are smaller apertures for
vessels and nerves.
Fig. 459.
Fig. 459. — VIEW OP THE LOWER HALF OP THE RIGHT ADULT HUMAN EYE, DIVIDED
HORIZONTALLY THROUGH THE MIDDLE. ±
The specimen from which this outline is taken was obtained by dividing the eye of a
man of about forty years of age in the frozen state. It was carefully compared with
other specimens obtained in a similar manner ; and in the drawing averages have been
given in any particulars in which differences among them presented themselves.
1, the cornea ; 1', its conjunctival layer ; 2, the sclerotic ; 2', sheath of the optic
nerve passing into the sclerotic ; 3, external or vascular layer of the choroid ; 3', its
internal pigmental layer ; 4, ciliary muscle, its radiating portion ; 4', cut fibres of the
circular portion ; 5, ciliary fold or process ; 6, placed in the posterior division of the
aqueous chamber, in front of the suspensory ligament of the lens ; 7, the iris (outer side) ;
7', the smaller inner side ; 8, placed on the divided optic nerve, points to the arteria
centralis retinae ; 8', colliculus or eminence at the passage of the optic nerve into the
THE SCLEROTIC COAT. 713
retina ; 8", fovea centralis retinae ; r, the nervous layer of the retina ; /, the bacillar
layer; 9, ora serrata at the commencement of the ciliary part of the retina ; 10, canal
of Petit; 11, anterior division of the aqueous chamber in front of the pupil; 12, the
crystalline lens, within its capsule ; 13, the vitreous humour ; a, a, a, parts of a
dotted line in the axis of the eye; b, b, b, b, a line in the transverse diameter. It will
be observed that from the pupil being placed nearer the inner side the axis of the eye-ball
a, a, does not pass exactly through the centre of the pupil, and that this line falls a
little to the inner side of the fovea centralis. The following letters indicate the centres
of the curvatures of the different surfaces ; assuming them to be nearly spherical, viz. :
c a, anterior surface of the cornea ; c p, posterior surface ; I a, anterior surface of the
lens ; I p, posterior surface ; s c p, posterior surface of the sclerotic ; r a, anterior surface
of the retina.
In connection with this figure the following average dimensions of the parts of the
adult eye in fractions of an English inch may be stated : —
Transverse diameter of the eyeball . . . . . . . 1*
Vertical diameter (Krause) ......... 0*96
Antero-posterior diameter . . . . . . . . . 0'96
Diameter of the optic nerve with its sheath . . . . . . 0'16
Diameter of the nervous part at its passage through the choroid membrane 0*09
Greatest thickness of the sclerotic, choroid, and retina together . . 0'08
Greatest thickness of the sclerotic posteriorly 0'05
Smallest thickness at the sides and in front ...... 0'025
Greatest thickness of the cornea 0'055
Distance from the middle of the posterior surface of the cornea to the
front of the lens 0'07
Antero-posterior diameter of the lens . . . . . . . 0'19
Transverse ditto 0'35
Greatest thickness of the ciliary muscle and ciliary processes together . . 0'06
Greatest thickness of the ciliary muscle ...... 0'035
Thickness of the iris 0'015
Length of the radius of curvature of the anterior surface of the cornea
(regarding it approximately as spherical) .0 '305
Radius of the posterior surface 0'275
Radius of curvature of the anterior surface of the lens . . . . 0'36
Radius of the posterior surface . . . . . . . . 0'21
Approximate length of the radius of curvature of the outer surface in the
posterior half of the retina . . (H85
Approximate radius of curvature of the external surface of the posterior
part of the sclerotic coat ......... 0*5
Distance of the middle of the posterior surface of the lens from the
middle of the retina 0'575
Distance between the centre of the spot of entrance of the optic nerve and
the middle of the fovea centralis retinae 0*14
Diameter of the base of the cornea ....... 0'48
Diameter of the base of the iris transversely . . . . . . 0'45
Diameter of the base of the iris vertically ...... 0*43
Diameter of the pupil . . . . 0'14
STRUCTURE. — The sclerotic coat is formed of connective tissue, and yields
gelatine on boiling. Its fibres are combined with fine elastic tissue, and
with fusiform and stellate nucleated cells, and are aggregated into bundles,
which are disposed in layers both longitudinally and transversely, the longi-
tudinal arrangement being most marked at the surfaces. These layers com-
municate at intervals, and the sclerotic presents a ramified and laminar
appearance on a vertical section.
A few blood-vessels permeate the fibrous texture in the form of a net- work
of the smallest capillaries with very wide meshes ; and in the neighbourhood
of the cornea a ring of greater vascularity exists, which has been already
noticed in the description of the sclerotic conjunctiva. The existence of
nerves in the sclerotic has not yet been allowed by all anatomists.
714
THE EYE.
THE CORNEA.
The cornea (cornea pellucida), the transparent fore parb of the external
coat, admits light into the interior of the ball. It is neaily circular in
shape, and its arc extends to about one-sixth of the circumference of the
whole globe ; it is occasionally widest in the transverse direction. Being
of a curvature of a smaller radius than the sclerotic, it projects forwards
beyond the general surface of curvature of that membrane, somewhat like
the glass of a watch : the degree of its curve varies, however, in different
persons, and at different periods of life in the same person, being more
prominent in youth and flattened in advanced age. Its thickness is in
general nearly the same throughout, viz., from ~ to ^ of an inch, except-
ing towards the outer margin, where it becomes somewhat thinner. The
posterior concave surface exceeds slightly in extent the anterior or convex, in
consequence of the latter being encroached on by the opacity of the sclerotic.
Fig. 460.
A
Fig. 461.
Fig. 460.— STRUCTURES OF THE CORNEA (after Bowman). A 5p, B & C, 30°
A, small portion of a vertical section of the cornea in the adult ; a, conjunctival
epithelium ; 6, anterior elastic lamina ; c to d, fibrous laminae with nuclear bodies inter-
spersed between them ; c, fibres shooting through some of these layers from the external
elastic lamina ; d, posterior elastic lamina ; e, internal epithelium. B, epithelium of
the membrane of Demours, as seen looking towards its surface. C, the same seen in
section.
Fig. 461. — SMALL PORTIONS OP A VERTICAL SECTION OF THE CORNEA AT BIRTH
(from Kolliker). 3fJ
The preparation has been treated with acetic acid. A, the anterior p.irt ; a, anterior
elastic lamina ; b, layer of closely set granules (probably small cells) placed under the
anterior elastic layer, with little fibrous structure ; c, developed fibrous tissue, with
united connective-tissue corpuscles ; B, posterior part of the cornea ; c, as before ; d,
posterior elastic layer.
THE CORXEA. 715
At its circumference the cornea joins the sclerotic part by continuity of tissue,
but always so as to be overlapped by the opacity of that structure like a
watch glass by the edge of the groove into which it is received.
STRUCTURE. — The cornea consists of a central thick fibrous part, the
cornea proper, covered in front by the conjunctival epithelium and the ante-
rior elastic lamina, and behind by the posterior elastic lamina or membrane
of Demours.
The cornea proper is a stratified structure, the constituent fibres of which,
continuous externally with those of the opaque sclerotic, are soft and com-
paratively indistinct, and between the strata of which are numerous delicate
anastomosing nucleated cells, of fusiform appearance as seen in vertical sec-
tions, but expanded in the direction of the laminae, and presenting in sections
parallel to the surface a stellate appearance. The strata, about sixty in
number, at a given spot (Bowman),* maintain frequent communications with
contiguous layers, so that they can be detached only for a very short dis-
tance : in consequence of this stratified composition the cornea may be
penetrated or torn most readily in the direction of the supposed laminse.
The transparency of the cornea is impaired by derangement of the relative
position, or by approximation of the strata to each other. The cornea
proper is permeable to fluid, and affords chondrin, not gelatine, on boiling
(J. Miiller).
There have been observed by v. Recklinghausen in the cornea of the frog, when
examined in a chamber of liquid connected with the microscope, not only a rich net-
work of anastomosing cells, but other cells also which change both their form and
position by means of processes thrown out from and disappearing again into their sub-
stance, like the pseudopods of amoebae. (Virchow's Archiv, Vol. 28, p. 157).
According to Henle, the anastomosing cells of the cornea are mere spaces devoid of
any walls distinct from the surrounding matrix, and are the only interlaminar spaces
naturally existing. (Systematise-he Anatomic, Vol. ii. p. 599).
The membranes investing the fibrous part of the cornea before and behind
are both of them structureless, with epithelium on their free surface.
The anterior elastic lamina (Bowman) is a transparent glassy stratum with-
out recognised texture, from ^^^th to -y^^th of an inch thick, and not
rendered opaque by acids. From the surface resting on the fibrous strata of
the cornea, a few fine threads are prolonged in a slanting direction, and are
lost among the more superficial of those strata : their action is supposed to
be to keep the membrane tied down smoothly to the cornea. The epithelium
on the front of this lamina is stratified, the superficial cells being flat, and
the main thickness formed of three or four layers of rounded cells, the deepest
of which are vertically elongated, so as to be nearly twice as long as broad.
It is right to mention that this epithelium in the horse, the ox, and the sheep, has a
much more remarkable appearance than in man, and one not to be accounted for by
the ordinarily presumed mode of growth of stratified epithelia ; for the deepest cells
are greatly elongated and larger than those which are immediately superimposed, and
have precisely the appearance of true columnar epithelium, the flat ends resting on
the subjacent elastic lamina, and the pointed extremities directed forwards.
The membrane of Demours or Descemet (posterior elastic lamina, Bowman),
not very closely united with the fibrous part of the cornea, is transparent and
glassy in appearance, firm and structureless, but very brittle and elastic ; and
* Lectures on the parts concerned in the operations on the eye, and on the structure of
the retina. London, 1849.
716
THE EYE.
when shreds are removed they curl up always with the attached surface
innermost. Its transparency is not impaired by acids, by boiliug in water,
or by maceration in alkalies. In thickness it varies between 3-oVo*k an(l
"2oVo~*k of an inch. At its circumference the membrane breaks up into
bundles of fine threads, which are partly continued into the front of the iris,
forming the " pillars of the iris," and partly into the fore part of the
choroid and sclerotic coats. It is lined with an epithelial covering, which
resembles that on serous membranes, consisting of a single layer of flat poly-
gonal transparent cells with distinct nuclei.
Blood-vessels and nerves. — In a state of health the cornea is not provided with
blood-vessels, except at the circumference, where they form very fine capillary loops
and accompany the nerves. The existence of lymphatics has not been satisfactorily
ascertained. The nerves of the cornea are very numerous, according to Schlemm.*
Derived from the ciliary nerves they enter the fore part of the sclerotic, and are from
twenty-four to thirty-six in number. Continued into the fibrous part of the cornea,
they retain their dark outline for ith to ith of an inch, and then becoming trans-
parent, ramify and form a network through the laminated structure.
MIDDLE TUNIC OF THE EYEBALL.
This coat consists of two parts, one a large posterior segment — the choroid,
reaching as far as the cornea, and formed chiefly of blood-vessels and pig-
mentary material ; the other, a small anterior muscular part — the irh.
Between these and connected with both is situated the white ring of the
ciliary muscle.
Fig. 462. Fig. 462. — CHOROID MEM-
BRANE AND IRIS EXPOSED
BY THE REMOVAL OP THE
SCLEROTIC AND CORNEA
(after Zinn). f
a, one of the segments of
the sclerotic thrown back ;
&, ciliary muscle and liga-
ment ; c, iris ; e, one of the
ciliary nerves ; /, one of the
vasa vorticosa or choroidal
veins.
THE CHOROID COAT.
The choroid coat of
the eye (tunica choro-
idea s. vasculosa) is a
dark brown membrane
lying between the scle-
rotic and the retina. It
reaches forwards to the
ciliary ligament, or
nearly to the cornea,
where it ends by a series of plaits or folds named ciliary processes, disposed
in a circle projecting inwards at the back of the circumferential portion of
the iris. Afc the hinder part, where the tunic is thickest, the optic nerve is
transmitted through a circular opening. The outer surface is rough, and
is connected to the sclerotic by loose connective tissue (lamina fusca of
* Berl. Encycl. Wort. art. Augapfel, Vol. iv. p. 22.
THE CHOROID COAT. 717
authors), and by vessels and nerves. The inner surface, which is smooth, is
lined by a continuous layer of pigmentary cells.
The ciliary processes, about eighty-five in number, are arranged radiately
in a circle. They consist of larger and smaller folds, without regular alter-
nation, and the small folds number about one-third of the large. Each of
the larger folds, measuring aboub -j^th of an inch in length and 4^th in
depth, forms a rounded projection at its inner end, which is free from the
Fig. 463. — CILIA.RY PROCESSES AS SEEN Fig. 463.
FROM BEHIND. f
1, posterior surface of the iris, with the
sphincter muscle of the pupil ; 2, anterior
part of the choroid coat ; 3, one of the
ciliary processes, of which about seventy are
represented.
pigment which invests the rest of the
structure ; but externally they become
gradually narrower, and disappear in
the choroid coat : the smaller pro-
cesses are only half as deep as the
others. At and near their internal or
anterior extremities the processes are
connected by lateral loop-like projec-
tions, and are separated from the iris by pigment. The plications of the
ciliary processes fit into corresponding plications of the suspensory ligament
of the lens.
STRUCTURE. — From a difference in the fineness of its constituent blood-
vessels, the choroidal coat resolves itself into two strata, inner and outer; —
the latter containing the larger branches, and the former the capillary
ramifications.
In the outer part of the coat are situated the branches of the vessels.
The arteries are large, and are directed forwards before they bend down-
wards to end on the inner surface ; whilst the veins (vasa vorticosa) are
disposed in curves as they converge to four of five principal trunks issuing
from the eyeball. In the intervals between those vessels are lodged elongated
and star-shaped pigment cells with very fine offsets, which intercommunicate
and form a network or stroma. Towards the inner part of the tunic, this
network passes gradually into a web without pigment : it resembles elastic
tissue in its chemical and physical properties.
The inner part of the choroid coat (tunica Ruyschiana s. chorio-capillaris)
is formed by the capillaries of the choroklal vessels. From the ends of the
large arteries the capillaries radiate in a star-like manner, and form meshes
which are more delicate and smaller than in any other texture, and are
finer at the back than the front of the ball. This fine network reaches as
far forwards as about |th of an inch from the cornea, or opposite to the
ending of the expansion of the optic nerve, where its meshes become larger,
and join those of the ciliary processes.
On the inner surface of the tunica Ruyschiana may be detected, according
to various authors, a structureless transparent membrane, the membrane of
Bruch, underlying the pigmentary layer.
The ciliary processes have the same structure as the choroid, of which they
are a part ; but the capillary plexus of the vessels, less fine, has meehes
718
THE EYE.
with chiefly a longitudinal direction ; and tbe ramified cells, fewer in
number, are devoid of pigment towards the free extremities of the folds.
The pigmentary layer (choroidal epithelium, membrane of the black pig-
ment) forms a thin dark lining to the whole inner surface of the choroid and
Fig. 464. — PIGMENT CELLS OP THE MIDDLE COAT
(after Kolliker).
A, small portion of the chorcid with the stellate
or ramified cells which form its stroma. B, pigment
cells, which cover the inner surface of the choroid ;
a, these cells seen from the surface, of hexagonal
form, and showing nuclei in their interior ; b, three
of the same cells viewed edgeways ; c, molecular
pigment, which fills the cells.
the iris. As far forwards as the ciliary pro-
cesses it consists of only a single layer of
flat six-sided cells, applied edge to edge liko
mosaic work. Each cell contains a nucleus
and more or less dense molecular contents,
accumulated in greatest abundance towards
the circumference of the cell, and parrly
obscuring the nucleus. On the ciliary pro-
cesses and the iris the pigment is several lay-
ers deep, and the cells, smaller and rounded,
are so filled with dark pigment as to cover
up the nucleus. In the eye of the albino,
pigment is absent both from the hexagonal cells and the ramified corpuscles
of the choroidal tunic.
It may be mentioned that in fishes, and in many mammals, including the ox and
the sheep, the eyes of which are often selected for dissection, the choroid, instead of
being uniformly lined with dark pigment, presents on a greater or less extent of its
back part a silvery layer named tapetum. The tapetum in ruminants consists of
tendinous fibres, and in carnivora and fishes of cells, filled, in the carnivora, with
granular matter (Leidig), in fishes with slender rods. On its inner surface is the
tunic of Ruysch, as well as the layer of hexagonal cells, which, however, is here
destitute of pigment.
THE IRIS.
The iris is the contractile and coloured membrane which is seen behind
the transparent cornea, and gives the tint to the eye. In its centre it is
perforated by an aperture — the pupil.
By its circumferential border, which is nearly circular, the iris is connected
with the choroid, the cornea, and the ciliary ligament and muscles : the free
inner edge is the boundary of the pupil, and is constantly altering its dimen-
sions during life. The iris measures J an inch across, and, in a state of
rest, from the circumference to the pupil about ^-th of an inch. Its surfaces
look forwards and backwards. The anterior, variously coloured in different
eyes, is marked by waving lines converging towards the pupil, near which
they join in a series of irregular elevations ; and, internal to these, other
finer lines pass to the pupil. The posterior surface is covered with dark
pigment ; and this being removed, there is seen at the margin of the pupil a
narrow circular band of fibres (sphincter muscle of the pupil), with which
lines radiating inwards are blended.
THE IRIS.
719
The pupil is nearly circular in form, and is placed a little to the inner
side of the centre of the iris. It varies in size according to the contraction
or relaxation of the muscular fibres, and this variation ranges from -g^th to
^rd of an inch. The movements of the iris regulate the quantity of light
admitted to the eyeball, and are associated with convergence of the optic
axes, and with the focal adjustment of the eye.
STRUCTURE. — Fibrous and muscular tissues form the framework of the
iris, and pigment is scattered through the texture. In front and behind is
placed a distinct layer of pigment cells. It is still matter of discussion
whether or not in the adult a delicate epithelium is continued from the
margin of the cornea over the front of the iris : it is admitted to exist in
childhood.
The fibrous stroma consists of fibres of connective tissue directed radiat-
ingly towards the pupil, and circularly at the circumference ; these, inter-
weaving with one another, form a net-like web which is less open towards
the surfaces.
The muscular fibre is of the non-striated kind, and is disposed as a ring
(sphincter) around the pupil, and as rays (dilatator) from the centre to the
circumference.
Fig. 465.
Fig. 465. — A SMALL PART OF THE
IRIS, SHOWING THE MUSCULAR
STRUCTURE (from Kolliker). ass
The specimen is from the albino-
rabbit, and has been treated with
acetic acid : a, the sphincter muscle
at the margin of the pupil ; 6, fas-
ciculi of the dilatator muscle ; c,
connective tissue with nuclear cells
rendered clear by the acid.
The sphincter is the flat
narrow band on the posterior
surface of the iris, close to
the pupil, and w about ^th
of &n inch wide. At the
edge of the pupil the fibres
are close together, but at the
peripheral border they are
separated, and form less com-
plete rings.
The dilatator, less apparent than the sphincter, begins at the ciliary or outer
margin of the iris, and its fibres, collected into bundles, are directed inwards
between the vessels and nerves, converging towards the pupil, and forming
a net-work by their intercommunications. At the pupil they blend with the
sphincter, some reaching near to its inner margin.
Pigmentary elements. — In the substance of the iris anteriorly and through-
out its thickness are variously- shaped and ramified pigment cells like those
in the choroid membrane. The pigment contained in them is yellow, or
of lighter or darker shades of brown, according to the colour of the eye. On
the fore part of the iris is a thin stratum of rather oval or rounded cells with
granular ramified offsets (an epithelial layer — Kolliker). At the posterior
surface is a covering of dark pigment — the uvea of authors ; this is con-
720
THE EYE.
tinuous with the pigmentary layer lining the choroid and the ciliary pro-
cesses, and consists of several strata of small roundish cells filled with dark
pigment. The colour of the iris depends on the pigment ; in the different
shades of blue eye it arises from the black pigment of the posterior surface
appearing more or less through the texture, which is only slightly coloured
or is colourless ; and in the black, brown, and grey eye, the colour is due
to the pigment scattered through the iris substance.
Fig. 466.
Fig. 466.— SECTIONAL VIEW OP THE CONNECTIONS OF THE CORNEA, SCLEROTIC, IRIS,
CILIARY MUSCLE, CILIARY PROCESSES, HYALOID MEMBRANE AND LENS, f
The specimen extends from the middle of the lens to the ora serrata on the inner side
of the right eye. C, the laminated cornea; cc, conjunctiva corneae ; cs, conjunctiva
scleroticse ; ce, epithelium of the conjunctiva ; ela, anterior elastic layer of the cornea
passing outwards in part into the conjunctiva; elp, posterior elastic layer; U, liga-
mentum pectinatum iridis, elastic ligament, spreading into the base of the iris, the
sclerotic, and the attachment of the radiated ciliary muscle ; S, the sclerotic at its
thinnest part ; A, the anterior aqueous chamber ; ap, the recess forming the posterior
division of the aqueous chamber ; sv, placed at the junction of the cornea and sclerotic,
points to the circular venous sinus or canal of Schlemin ; ea, epithelium behind the
cornea indicated by a dotted line ; ei, epithelium in front of the iris similarly indicated ;
ir, radiating muscle of the iris ; io, divided fibres of the orbicular muscle ; u, pigment
layer or uvea ; In, centre of the crystalline lens ; Ic, capsule of the lens ; Ice, layer of
cells in front of the lens ; cir, radiating ciliary muscle or tensor choroidese ; do, divided
orbicular fibres ; dp, ciliary process, along the inner border of which a layer of pigment
is continued from the choroid to the uvea, excepting at the end of the process ; Ch,
choroid membrane ; R, the retina close to the ora serrata ; re, the ciliary part of the
retina, the structure of which is imperfectly represented ; V, the vitreous humour ; k,
the hyaloid membrane ; P, canal of Petit ; k', the hyaloid membrane continued behind
the canal to the capsule of the lens ; Z, zonule of Zinn, and II, suspensory ligament of
the lens proceeding from the hyaloid covering the ciliary process to the front of the capsule
of the lens.
CILIARY MUSCLE AND LIGAMENT. 721
The vessels and nerves have a radiating arrangement through the stroma; the former
giving rise to rings, one at the circumference, the other near the pupil ; and the latter
forming a network. (See the description of the vessels and nerves of the vascular
coat.)
Pupillary membrane (membrana pupillaris). — In foetal life a delicate transparent
membrane thus named closes the pupil, and completes the curtain of the iris. The
pupillary membrane contains minute vessels, continuous with those of the iris and of
the capsule of the crystalline lens; they are arranged in loops, which converge towards
each other, but do not quite meet at the centre of the pupil. At about the seventh or
eighth month of foatal life these vessels gradually disappear; and, in proportion as the
vascularity diminishes, the membrane itself is absorbed from near the centre towards
the circumference. At the period of birth, often a few shreds, sometimes a larger
portion, and occasionally the whole membrane is found persistent. (See also the
account of the development of the eye.)
CILIARY MUSCLE, LIG AMENTUM PECTINATUM, AND CIRCULAR SINUS.
When the outer coat of the eyeball is separated from the choroid, a circular
groove is seen passing round on the inner surface of the sclerotic, at its
corneal margin. This groove is the outer wall of a venous canal, the sinus
circularis iridis or canal of Schlemm. On the middle coat a corresponding
groove, which completes the canal, is seen, — and this is bounded in front
by a torn membranous edge bounding the anterior surface of the iris, the
ligameutum pectinatum, while the thickest part of the white ring of the
ciliary muscle is behind it. This canal communicates with other venous
spaces which give an erectile appearance to the tissue at the base of the
ciliary processes.
The ligamentum pectinatum consists of slight festoon-like processes of the
fibres of the iris, lying in a transparent elastic fibrous tissue continuous with
the posterior elastic layer of the cornea. It is a more developed structure
in the eyes of the sheep and ox than in the human eye, and in them the
festooned processes are prominent, giving a milled appearance like that of the
edge of a coin.
The ciliary muscle (Bowman) forms a ring of unstriped muscular tissue
about T^th of an inch broad on the fore part of the choroid. Its fibres,
yellowish-white in colour, and longitudinal in direction, are attached in front
to the inner surface of the sclerotic coat ; and are also connected with the
terminal fibres of the posterior elastic layer of the cornea. From that
origin the fibres are directed inwards and backwards in a manner which in
a section appears radiated, and end by joining the choroid coat opposite and
beyond the ciliary processes. The muscle is soft, and ramified pigment-cells
are scattered through its substance.
Concealed by the longitudinal or radiated fibres is a ring of fibres taking
a circular direction, and which were still described as the ciliary ligament
after the radiated fibres had been admitted to be muscular. This set consti-
tutes the circular muscle of H. Miiller.
The ciliary muscle appears to be in some way effective in producing the
change in the form of the lens which takes place in accommodation of the
eye to near vision (see Allen Thomson in " Glasgow Medical Journal" for
1857).
VESSELS AND NERVES OF THE MIDDLE TUNIC OF THE EYE.
The arteries of the choroid and the ciliary processes are derived from the
posterior and anterior ciliary vessels. The posterior consist of two sets, distin-
guished as the short and the long. The short (posterior) ciliary branches of the
3 B
722
THE EYE.
ophthalmic artery pierce the sclerotic close to the optic nerve, and divide
into branches which pass forward in meridional directions in the choroid
membrane. Communicating freely they diminish in size, and entering the
choroid form a close network of fine capillaries (tunica Euyschiana) already
described.
Fig. 467.
Fig. 468.
Fig. 467. — LATERAL VIEW OP
THE ARTERIES OF THE CHO-
ROID AND IRIS (from Ar-
nold), f
a, optic nerve ; &, part of
the sclerotic left behind, the
greater part and the cornea
having been removed ante-
riorly ; c, ciliary muscle ; d,
iris ; 1, posterior ciliary ar-
teries piercing the sclerotic and
passing along the choroid ; 2,
one of the long posterior
ciliary arteries ; 3, several of
the short or anterior ciliary
arteries.
The veins of the choroid
coat constitute an outer
layer, partially separable
from the arterial network,
and easily recognised by
the direction of the larger
vessels. These converge
to four nearly equidistant
trunks, which pass through
the sclerotic about half
way between the margin
Fig. 468. — LATERAL VIEW OF
THE VEINS OF THE CHOROID
(from Arnold).
The preparation is similar to
that represented in the pre-
vious figure. 1, 1, two trunks
of the vense vorticosse at the
place where they leave the
choroid and pierce the sclerotic
coat.
of the cornea and the entrance of the optic nerve, and pour their contents
into the ophthalmic vein. From their whorl-like arrangement they are
known as the vasa vorticosa.
The blood-vessels of the ciliary processes are very numerous, and are derived
from the anterior ciliary, and from those of the fore part of the choroidal
membrane. Several small arterial branches enter the outer part of each ciliary
process, at first running parallel to each other and communicating sparingly.
As they enter the prominent folded portion, the vessels become tortuous, sub-
divide minutely, and inosculate frequently by cross branches. Finally they
form short arches or loops, and turn backwards to pour their contents into
the radicles of the veins.
On the free border of the fold, one artery, larger than the rest, extends
BLOOD-VESSELS OF THE IRIS. 723
the whole length of each ciliary process, and communicates through inter-
veuing vessels with a long venous trunk which runs a similar course on the
attached surface.
Fig. 469.
Fig. 469.— INJECTED BLOOD-VESSELS OF THE CHOROID COAT (from Sappey). &
1, one of the larger veins ; 2, small communicating vessels ; 3, branches dividing into
the smallest vorticose vessels.
Arteries of the iris. — The special arteries of the iris are the long ciliary
and the anterior ciliary.
The long (posterior) ciliary arteries, two in number, and derived from the ophthal-
mic, pierce the sclerotic a little before, and one on each side of, the optic nerve.
Having gained the interval between the sclerotic and choroid coats, they extend
horizontally forwards through the loose connective tissue (membrana fusca) to the
ciliary muscle. In this course they lie nearly in the horizontal plane of the axis of the
eye-ball, the outer vessel being however a little above, and the inner one a little below
the level of that line. A short space behind the fixed margin of the iris each vessel
divides into an upper and a lower branch, and these, anastomosing with the corre-
sponding vessels on the opposite side and with the anterior ciliary, form a vascular
ring (circulus major) in the ciliary muscle. From this circle smaller branches arise
to supply the muscle; whilst others converge towards the pupil, and there, freely com-
municating by transverse offsets from one to another, form a second circle of anasto-
mosis (circulus minor], and end in small veins.
The anterior ciliary arteries, five or six in number, but smaller than the vessels
just described, are supplied from the muscular and lachrymal branches of the ophthal-
mic artery, and pierce the sclerotic about a line behind the margin of the cornea ;
finally, they divide into branches which supply the ciliary processes, and join the
circulus major.
Besides these special arteries, numerous minute vessels enter the iris from the ciliary
processes.
The veins of the iris follow closely the arrangement of the arteries just
described. The circular sinus communicates with this system of vessels.
3 B 2
724
THE EYE.
The nerves for the supply of the iris are named ciliary : they are nume-
rous and large ; and, before entering the iris, divide in the substance of the
ciliary muscle.
Fig. 470.
Fig. 471.
Fig. 470. — VESSELS OP THE CHOROID, CILIARY PROCESSES AND IRIS OF A CHILD (from
Kolliker after Arnold). >-<>
a, capillary network of the posterior segment of the choroid ending at £, the ora
serrata ; c, arteries of the corona ciliaris, supplying the ciliary processes d, and passing
into the iris e ; f, the capillary network close to the pupillary margin of the iris.
Fig. 471. — FRONT VIEW OF THE BLOODVESSELS OF THE CHOROID COAT AND IRIS FROM
BEFORE (from Arnold). !_•
A, interior part of the choroid : B, iris ; C, ciliary muscle, &c. ; 1, 1, long posterior
ciliary arteries ; 2, five of the anterior ciliary arteries ramifying towards the outer margin
of the iris ; 3, loop of communication between one of the anterior and one of the long
posterior ciliary arteries ; 4, internal circle and network of the vessels of the iris ; 5,
external radial network of vessels.
Fig. 472. Fig. 472. — LATERAL VIEW OF THE CILIARY
NERVES (from Arnold).
a, optic nerve ; b, hack part of the sclerotic ;
c, ciliary muscle, &c. ; d, iris ; e, outer surface
of the choroid coat; 1, five of the ciliary nerves
passing along the sheath of the optic nerve,
piercing the sclerotic posteriorly, and thence
passing forward on the choroid membrane to
the ciliary muscle and iris. The nerves are
represented too large.
The ciliary nerves, about fifteen in num-
ber, and derived from the lenticular ganglion
and the nasal branch of the ophthalmic division of the fifth nerve, pierce the
sclerotic near the entrance of the optic nerve, and come immediately into contact with
RETINA OR XERYOUS TUXIC. 725
the choroid. They are somewhat flattened in form, are partly embedded in grooves
on the inner surface of the sclerotic, and communicate occasionally with each other
before supplying the cornea and entering the ciliary muscle. AY hen the sclerotic is
Fig. 473.
Fig. 473. — DISTRIBUTION OP
NERVES IN THE IRIS (from
Kolliker). 5JL
The preparation was taken from
the eye of an albino rabbit, and
Avas treated with soda, a, smaller
branches of the ciliary nerves ad-
vancing from the choroid ; 6, loops
of union between them at the mar-
gin of the iris ; c, arches of union
in the iris ; </, finer network in the
inner part; d, some of the termi-
nations of single nerve- filaments
in the outer part of the iris ; e,
sphincter pupillae muscle.
carefully stripped from the subjacent structures, these nerves are seen lying on the
surface of the choroid. Within the ciliary muscle the nerves subdivide minutely, a few
being lost in its substance, but the greater number pass on to the iris. In the iris the
nerves follow the course of the blood-vessels, dividing into branches, which com-
municate with one another as far as the pupil. In the iris they soon lose their dark
outline, and their mode of termination is not ascertained.
RETINA OR NERVOUS TUNIC.
The retina is a delicate almost pulpy membrane, which contains the ter-
minal part of the optic nerve. It lies within the choroid coat, and rests on
the hyaloid membrane of the vitreous humour. It extends forwards nearly
to the outer edge of the ciliary processes of the choroid, where it ends in a
finely indented border — or a serrata. From this border there is continued
Fig. 474. — THE POSTERIOR HALF OF THE Fig. 474.
RETINA OP THE LEFT ETE VIEWED
FROM BEFORE (after Henle). f
s, the cut edge of the sclerotic coat ;
ch, the choroid ; ?*, the retina : in the
interior at the middle the macula lutea
with the depression of the fovea centralis
is represented by a slight oval shade ;
towards the left side the light spot
indicates the colliculus or eminence at
the entrance of the optic nerve, from the
centre of which the arteria centralis is
seen spreading its branches into the
retina, leaving the part occupied by the
macula comparatively free.
onwards a thin layer of transparent
nucleated cells (not nerve-elements)
of an elongated or cylindrical form,
constituting the pars ciliaris retinae.
which reaches as far as the tips of the ciliary processes, and there gradually
disappears. The thickness of the retina diminishes from behind forwards. In
the fresh eye it is translucent and of a light pink colour ; but after death it
soon becomes opaque, and this change is most marked under the action of
726 THE EYE.
water, alcohol, and other fluids. The outer surface is rough or slightly
flocculent when the choroid is detached, and is in contact with the pig-
mentary layer ; and from it a more or less complete stratum may be raised
with care in a perfectly fresh eye. This layer, at first called membrane of
Jacob from its discoverer, is now generally recognised as the columnar layer.
The inner surface of the retina is smooth, and is merely applied to the
vitreous body within it : on it the following objects may be seen. In the
axis of the ball is a yellow spot — macula lutea (limbus luteus, Sommerriug),
which is somewhat elliptical in shape, and about -^th of an inch in diameter :
in its centre is a slight hollow, fovea centralis, and, as the retina is thinner
Fig. 475.
Fig. 475. — SECTION THROUGH THE MIDDLE OP THE OPTIC NERVE AND THE TUNICS OP THE
EYE AT THE PLACE OP ITS PASSAGE THROUGH THEM (from Kolliker after Ecker). f
The drawing was taken from a chromic acid preparation : a, arteria centralis retinae ;
6, fasciculi of optic nerve fibres with neurilemuia ; c, sheath of the optic nerve, passing
into </, the sclerotic coat ; c", outermost pigmental layer of the choroid or membraua
fusca ; d, choroid and inner pigment-layer ; e, /, columnar layer of the retina ; g, the
two granular layers ; A, layer of nerve-cells ; i, layer of nerve-fibres ; &, colliculus or
eminence at the entrance of the optic nerve ; I, lamina cribrosa.
here than elsewhere, the pigmentary layer of the choroid is visible through
it, giving rise to the appearance of a hole through the tunic. About T^th of
an inch inside the yellow spot is the round disc, porus opticus, where the
optic nerve expands, and in its centre the point from which the vessels of
the retina branch. At this place the nervous substance is slightly elevated
so as to form an eminence (colliculus nervi optici).
STRUCTURE. — The retina, when examined microscopically in vertical
sections, exhibits a series of dissimilar strata, together with structures not
confined to one stratum. (1st) Externally is the columnar layer ; (2nd),
in the middle is the granular layer, comprising the external nuclear, the
iuternuclear, the internal nuclear, aud the molecular layers ; and (3rd)
internally is the nervous layer, consisting of three strata, one of nerve-cells,
another of nerve-fibres — the ramifications of the optic nerve, and, on the
inner surface of this last, a limiting membrane. (4th) Traversing the strata
from the columnar layer to the limiting membrane, are placed vertical fibrils
of varying kinds at different depths, and not fully ascertained to be con-
tinuous,— the radiating fibres of Miiller. (5th) Blood-vessels distributed
in the retina, are placed chiefly towards the inner surface.
COLUMNAR LAYER OF THE RETIXA.
727
1. The columnar layer (stratum bacillorum), consists of innumerable thin
rods, placed vertically side by side like palisades, and of other larger bodies,
more or less thickly interspersed amoog these, and named cones. These
Fig. 476.
Fig. 476. — VERTICAL SECTION OP A SMALL PART OF
THE RETINA (after Kolliker). ^
A, entire section of a small part of the retina ; B,
two cones represented separately in their connection
with the fibres of Miiller and other structures ; C,
two rods represented separately iu their connection
with the granules, fibres of Miiller, and the nerve-
cells ; 1, columnar layer ; a, in A and C, the rods,
in B, the terminal part of the cone ; b, cones ; 2,
granular layer ; c, outer layer of nuclei (striated
corpuscles of Henle) ; d, inner layer of nuclei ; /,
internuclear layer ; 3, nervous layer ; g, fiue mole-
cular substance outside h, the nerve-cells ; &, nerve-
fibres ; I, membraua liinitans ; e, inner ends of the
fibres of Miiller resting on the limiting membrane.
structures are glistening, soft, easily des-
troyed, and lose their characters quickly in
fluids. The rods are of uniform diameter,
and are abruptly truncated externally. The
cones are flask-shaped in the inner part of their
extent, and taper to a rod-like extremity ex-
ternally. Each cone rests on a pyriform cell
continuous with it, and forming the extremity
of a fibre of Miiller ; while the rods end
internally in pointed extremities ranging with
these pyriform cells, and represented as formed by similar bodies (Kolliker);
but this continuity with Miillerian fibres is still disputed. The dilated
portions of the cones present granular contents, and a similar appearance is
described in the inner halves of the rods. At the outer ends the rods pro-
ject somewhat farther than the cones. When the outer surface of the
retina is viewed about midway between its centre and margin with a strong
enough magnifying power, a number of minute globular-looking bodies, the
ends of the rods, appear ; and between them, at a deeper level, other
Fig. 477.
Fig. 477. — OUTER SURFACE OP THE COLUMNAR LAYER OP
TBE RETINA (from Kolliker). — -
a, part of the columnar layer within the macula lutea,
where only cones are present ; b, part near the macula,
where a single row of rods intervenes between the cones ; c,
from a part of the retina midway between the macula and
the ora serrata, showing a preponderance of the rods.
transparent larger bodies, the swellings of the cones,
are seen, with a smaller circle within each — the end
of its narrower part. Towards the margin the rods
become more numerous ; near the centre the cones
predominate ; and in the macula lutea the cones alone are seen.
2. The external and internal nuclear divisions of the granular layer are
two collections of rounded and oval corpuscles, refracting light pretty strongly.
The corpuscles of the internal nuclear layer are small cells with large nuclei,
728 THE EYE.
as are also some, at least, of those of the outer layer, namely, the pyriform
bodies supporting the cones. But, according to recent investigations of
Henle, whose statements have been corroborated by Ritter as holding good
in the mammals generally, the bodies which constitute the bulk of the outer
nuclear layer, are elliptical corpuscles, which, when perfectly fresh, exhibit
transverse striation similar to muscular fibre, to the extent of three dark
lines alternating with clear substance in each, but which soon break up into
globules.
Fig. 478. Fig. 478. — STRIPED ELLIPTICAL CORPUSCLES OP THE EXTERNAL NUCLEAR
LAYER OF THE RETINA (from Henle). ^-p
The internuclear layer, which lies between the layers now
referred to, is a clear space of unequal depth, vertically striated,
and having likewise a molecular appearance. The molecular
basis is more marked in a thin stratum which intervenes be-
tween the internal nuclear layer and the nerve-cells, and which,
therefore, has been distinguished as the molecular layer.
3. Nervous layer. — a. The cellular layer consists of nerve-cells with a
fine molecular material interspersed among them. At the bottom of the
eye over the yellow spot they are thickest (from 8 to 10 cells deep), and
decrease in quantity in front ; so that at a fifth of an inch from the ora
serrata they are only scattered in clusters. Around the entrance of the
optic nerve there is only a single stratum of these elements. The cells whon
fresh are transparent and nucleated, being roundish or pear-shaped in out-
line, and are furnished with from two to six ramified offsets. By their
internal offsets the cells are continuous with the nerve-fibres beneath ; by
horizontal offsets they are united one with another ; and by those which
pass outwards they are connected with the corpuscles of the internal nuclear
layer.
6. The nerve-fibre layer consists of nerve-fibres directed forwards from the
optic nerve, and collected into small bundles, which, compressed laterally,
intercommunicate and form a delicate web with narrow elongated meshes.
This stratum diminishes in thickness forwards, and ends at the ora serrata :
it forms a continuous membrane, except at the yellow spot, where the nerve
fibres are wanting. According to Bowman, the fibres, which lose their dark
outline on reaching the retina, consist there of an axis-cylinder only. It is
now well established that they terminate in the nerve-cells on which they
lie, and this is the only mode of their termination which has been fully
ascertained.
c. Membrana limitans and connective tissue. — The limiting membrane lines
the inner surface of the retina, separating it from the vitreous body. It is
an extremely thin and delicate membrane, which can be detached in shreds;
and it agrees with the other glassy membranes of the eye-ball in not being
affected by alkalies, maceration, or boiling. On its retinal surface it is
studded with the broadened insertions of vertical threads of connective tissue,
which separate the nerve-fibres into bundles, ar,d form the inner parts of the
Miillerian fibres. Nuclei apparently exist both in these and in the mem-
brana limitaus itself. Delicate homogeneous connective tissue, likewise,
enters into the composition of the layers of the retina as far outwards as the
bases of the rods and cones, and gives there the appearance of a horizontal
line, the external limitary membrane of Schultze.
4. Radiating fibre s of Multer, and connections of the different elements of the
retina. — From the foregoing description it will be gathered that the history of
MULLEKIAN FIBRES.— BLOOD-VESSELS OF EETINA. 729
the Mtillerian fibres is still incomplete. Indeed, the minuteness and delicacy
of their structure renders their investigation one of the most difficult sub-
jects of anatomical inquiry. Heinrich Miiller, to whom science chiefly owes
the advance which has of late years been made towards the elucidation of
the minute structure of the retina, described radiating fibres, extending verti-
cally from the rods and cones to the membrana limitans, interrupted in their
course by the corpuscles of the outer and inner nuclear layers, and connected
with the nerve-cells. He subsequently recognised the vertical fibres in the
internal layers as connective tissue, — a view now universally adopted. It
appears to be clearly established, that from the pyriform corpuscles at the base
of each cone a thread passes inwards to a corpuscle of the internal nuclear
layer. It is also stated that more slender threads unite the rods with the
deep layers ; and Kolliker represents a thread passing out from a corpuscle
of the internal nuclear layer as afterwards dividing into branches, on which
are placed corpuscles of the external nuclear layer, and which terminate in
rods. This account of the structure seems best to accord with the physio-
logical view now very generally held, that the columnar layer is the more
immediate seat of the formation of a distinct image in vision, and of the
reception of visual impressions from rays of light impinging upon the retina.
It is right to state, however, that a different view is taken by Henle, who
believes that the rods are free, and that the fibres observed by H. Miiller
and Kolliker are artificial products, the result of coagulation by re-agents.
Heule regards the retina as composed of an outer part, which he terms the
mosaic layer, and which comprises the columnar structures of Jacob's mem-
brane, and the external nuclear layer, and is destitute of blood-vessels ; and
an inner nervous part comparable to the structure found in the cerebral con-
volutions, and consisting of a stratum of nerve fibres and of two strata of
nerve cells alternating with granular strata ; the corpuscles of the internal
nuclear layer being considered by him as nerve cells of a smaller order than
those of the cellular layer.
5. Vessels of the retina. — An artery enters and a vein leaves the retina
between the bundles of fibres of the optic nerve.
The artery (arteria centralis retinae) is an offset of the ophthalmic, and
divides into four or five primary branches as soon as it enters the eye-ball.
These larger offsets are situated at first on the inner surface of the nerve
fibres, but they soon pass between these into the stratum of nerve-cells,
where they form a network of very fine capillaries with rather wide meshes,
which reaches in front to the ora serrata.
The vein corresponding to this artery has a similar distribution : it termi-
nates in the ophthalmic vein. In animals there is a circular vessel (circulus
venosus retina) following the line of the ora serrata.
Constituents of the retina in the yellow spot. — In this part of the retina
the several layers above described undergo some modification : the following
are the alterations in the strata from without inwards. In the columnar
layer, only the cones are present, but they are set close together, and are
smaller than elsewhere. The granular layer is absent opposite the fovea
ceutralis. The nervous layer is thus modified : the nerve-cells cover the
whole spot, like laminated epithelium, and rest internally on the membrana
limitans ; but the molecular substance outside them is absent over the
fovea centralis ; the nerve-fibres extend only into the circumference of the
spot amongst the cells, without forming a layer over it. The fibres of
Miiller are found at the circumference but not over the fovea centralis ; they
have an oblique, almost horizontal direction, and present a specially nerve-
730 THE EYE.
like appearance. Only capillary vessels occupy the yellow spot, the larger
branches passing round it.
Fig. 479.
Fig. 479. — VERTICAL SECTION OP THE RETINA THROUGH THE MIDDLE OP THE FOVEA
CENTRALIS (from Henle.) ~-
This figure is taken from a preparation of the human retina hardened in alcohol, and
is designed to show the peculiarities of this part as compared with other regions of the
retina, viz., the obliquity of the Miillerian fibres, the thinness of the layer of nerve-
fibres, and the absence of the granular layer in the centre, a, 6, cones of the columnar
layer ; c, external nuclear layer ; d, internal nuclear layer ; /, external fibrous layer ;
g, molecular substance next to h, the ganglionic layer ; Tc, the layer of nerve-fibres ;
I, the internal limiting membrane.
The yellow colour of the macula lutea is deepest towards the centre, and
is due to a pigment which imbues all the layers except the columnar : it
does not appear to be contained in cells, and is soon removed after death by
the action of water.
Ciliary part of the retina. — The structure which has been named the
ciliary part of the retina is situated in front of the ora serrata, and extends
thence over the inner ends of the ciliary processes to the base of the iris
(therefore, over the whole corona ciliaris). Though entirely destitute of the
nervous parts of the retinal structure, it is still in continuity with the sub-
stance of the retina, and in the form of a grey membrane, adheres to the
ciliary processes and zonule of Zinn, and is usually in great part detached
from the neighbouring parts along with the latter. According to Kolliker,
this layer consists of elongated nucleated cells, which in the human subject
are broad externally, and with flat or forked bases set upon the internal
limiting membrane. He regards these cells as probably corresponding to the
Miillerian fibres, and as constituting in this place the only representative of
the retinal structure.
THE VITREOUS BODY.
731
On the structure of the retina may be consulted Heinrich Miiller, in Siebold und
Kolliker's Zeitschrift, 1851 and 1856; M. Schultze, "Obs. de retinae Struct, penit.,"
1859 ; Goodsir, in Edin. Med. Journal, 1855 ; Kolliker, Handbuch d. Gewebelehre,
4th ed., 18(53 ; and Henle, Handbuch d. System. Anatomic, vol. ii., 1866.
Fig. 480.
Fig. 481.
Fig. 480. — VERTICAL SECTION THROUGH THE CJIOROID AND RETINA KEAR THE ORA
SERRATA (from Kolliker). f
a, hyaloid membrane ; of, indications of fibres which radiate from the anterior margin
of the retina into the vitreous body ; 6, limiting membrane and fibrous layer of the
retina ; c, ganglion! c layer with a few cells shown ; d, inner nuclear layer ; et inter-
nuclear substance ; /, outer nuclear layer ; g, columnar layer ; h, dark pigment ; i,
middle layer of the choroid ; I, beginning of one of the ciliary processes ; m, ciliary part
of the retina. (The recess shown at a' is not constant.)
Fig. 481. — A SMALL PORTION OF THE CILIARY PART OF THE RETINA (from Kolliker). ^~2-
A, human ; B, from the ox j 1, pigment-cells ; 2, cells forming the ciliary part.
THE VITKEOUS BODY.
The vitreous body is the largest of the transparent parts occupying the
centre of the eye-ball. Globular in form, it occupies about four- fifths of the
ball, and supports the delicate retina, being in contact with the membrana
limitans. On the fore part it is hollowed out for the reception of the lens
and its capsule, and behind it is more closely connected with the retina than
at the sides, having received at that part offsets of the retinal vessels in
foetal life. It is quite transparent, and like a thin jelly in its interior. Its
surface is formed by a thin enveloping glassy membrane, named hyaloid, and
as long as this membrane is entire, it retains its form in water. No vessels
enter it, and its nutrition must be therefore dependent upon the surrounding
vascular textures — viz., the retina, and the ciliary processes.
The hyaloid is an extremely thin and clear membrane. When traced
forwards it is found to be connected, opposite the outer part of the ciliary
processes, with a firm membrane passing in front of the marginal part of
the lens (suspensory ligament), while a thinner layer, proceeding inwards
from this, becomes united with the posterior layer of the capsule of the
lens, so that it is doubtful whether or not the membrane is prolonged
between the capsule and the vitreous body. On the inner surface of the
hyaloid are a few delicate nuclei. Fibres have been supposed to be pro-
732
THE EYE.
longed inwards from it, to form cells for the contained fluid, but obser-
vations with the microscope do not show any in the adult, though in the
foetus there are fibres in the interior of the vitreous mass, with "minute
Fig. 482.
Ic
Fig. 482. — VERTICAL SECTION OF A PART OP THE EYEBALL, SHOWING THE CONNECTIONS OP
THE CORNEA, SCLEROTIC, IRIS, CILIARY MUSCLE, HYALOID, AND LENS, f
The full description of this figure will be found at p. 720 ; the following references
apply to the lens and parts connected with it. A, the anterior aqueous chamber in front
of the pupil ; ap, the recess forming the posterior division of the aqueous chamber, the
iris resting between this and the pupil on the surface of the lens ; ir, radiating fibres of
the iris or dilatator pupillse muscle ; to, orbicular fibres or sphincter muscle ; u, pigment
layer of the iris or uvea ; In, the lens at its centre ; Ic, its capsule ; Ice, granular or
cellular layer in front of the lens ; this layer is seen to terminate abruptly at the margin
of the lens, where the new fibres of the lens are developed, and from whence the nuclei
of the fibres extend for a certain depth inwards in an irregular plane in the growing
lens ; A, the hyaloid membrane ; Z, the zonule of Zinn ; P, the canal of Petit ; II,
in front of it the suspensory ligament of the lens ; h', the part of the hyaloid which
closes the canal of Petit behind and extends to the posterior surface of the lens ; V, the
vitreous humour.
nuclear granules" at their point of junction. (Bowman.) It is still
doubtful how far the appearances of lamination produced by the action of
chromic acid, or of radiated fibrillation resulting from congelation, are true
indications of any actually existing structure in the interior of the vitreous
humour.
The fluid collected from the vitreous body by puncturing it resembles
water : it contains, however, some salts with a little albumen.
THE LEXS. 733
THE LENS AND ITS CAPSULE.
The lens, enclosed in a capsule, is situated behind the pupil, and in front
of the vitreous body.
The capsule of the lens, a transparent glass-like membrane closely sur-
rounding the contained body, is hard and brittle, especially in front, but
very elastic and permeable to fluid. The anterior surface is in contact with
the iris towards the pupil, and recedes from it slightly at the circumference ;
the posterior rests closely on the vitreous body. Around the circumference
is a space to be afterwards noticed, the canal of Petit. The fore part of the
capsule is several times thicker than the back, as far out as to -y^-th of an
inch from the circumference, where the suspensory ligament joins it ; but
beyond that spot it becomes thinner, and it is thinnest behind. Tn its nature
the capsule of the lens resembles the glassy membrane at the back of the
cornea, for it is structureless, and remains transparent under the action of
acids, alcohol, and boiling water ; and when ruptured, the edges roll up
with the outer surface innermost. (Bowman.)
Connecting the anterior wall of the capsule closely to the lens is a single layer of
granular and nucleated polygonal cells, which ends abruptly where the capsule comes
in contact with the hyaloid membrane. The place of termination of this cellular
layer round the margin of the lens corresponds to the line from which the fibres of
the lens are developed. There is no such layer of cells on the posterior wall of the
capsule, but in hardened specimens various reticulated appearances may be detected,
which probably arise, as supposed by Henle, from the pressure one on another of glo-
bules of a fluid separated from the lens after death, and known as liquor Morgagni.
No vessels enter the capsule of the lens in the adult. In the foetus it receives an
artery behind, which is named the capsular artery. This vessel leaves the arteria
centralis retinae at the centre of the optic nerve, and passing through the substance of
the corpus vitreum, enters the posterior portion of the capsule of the lens, where it
divides into radiating branches. These form a fine network, turn round the margin of
the lens, and extend forwards to become continuous with the vessels in the pupillary
membrane and the iris.
Some authors (Albinus, Zinn, &c.) state that they have traced vessels from the
capsule into the substance of the lens itself.
THE LENS.
The lens (lens crystalliua) is a doubly convex transparent solid body, with
a rounded circumference. Its convexity is not alike on the two surfaces,
Fig. 483. — LAMINATED STRUCTURE OF THE CRYSTAL- Fig. 483.
LINE LENS (from Arnold). *
The laminae are split up after hardening in alcohol.
1, the denser central part or nucleus; 2, the succes-
sive external layers.
being greatest behind, and the curvature is
less at the centre than towards the margin.
It measures about ^rd of an inch across, and
^-th from before backwards. In a fresh lens
the outer portion is soft and easily detached ;
the succeeding layers are of a firmer consis-
tence ; and in the centre the substance becomes
much harder, constituting the nucleus. On the anterior and posterior
surfaces are faint white lines directed from the poles towards the cir-
cumference ; these in the adult are somewhat variable and numerous on
734
THE EYE.
the surface, but in the foetal lens throughout, and towards the centre of the
lens in the adult, they are three in number, diverging from each other like rays
at equal angles of 120°. The lines at opposite poles have an intermediate
position (not being over one another) : they are the edges of planes or septa
projecting vertically inwards to the centre of the lens, and receiving the ends
of the lens-fibres which are collected upon them.
Fig. 484. — OUTLINES ILLUSTRATING THE COURSE OP THE FIBRES IN THE POSTAL
CRYSTALLINE LENS. |
This diagram represents the typical or more simple state of the fibres in the full-
grown foetal or infantile condition ; the three dotted lines radiating at equal angles of
120° from the centre indicate the position of the intersecting planes, where they reach
the surface; the figures 1, 2, 3, 4, 5, and 6, indicate certain fibres selected arbitrarily at
equal distances in one- sixth part of the lens to show their course from the front to the
back ; A, the anterior surface ; B, the posterior surface ; C, the lateral aspect : in these
several figures, for the sake of clearness, a few lines only are introduced into the upper
third, while in the lower two-thirds a greater number are marked ; but no attempt is
made to represent the number existing in nature ; the parts of the dotted line marked c,
are on a level with the centre of the several lenses.
p. 4gg Fig. 485. — FRONT VIEW OF THE FIBROUS
STRUCTURE OP THE ADULT LENS (from
Sappey after Arnold), f
In this figure more numerous planes of
intersection of the fibres are shown than
in fig. 484.
STKUCTUKE. — When the lens has
been dried, or hardened by immer-
sion in spirit, boiling water, or other
fluid capable of rendering it firm
and white, concentric laminae, nar-
rowing to a point at the poles, may
be detached from it. The laminae
are further composed of microscopic
fibres, which adhere together by
wavy or slightly serrated margins.
The lens is albuminous in its composition, and is devoid of blood-vessels ;
and at the planes of intersection a finely granular homogeneous material
takes the place of the fibres.
FIBRES OF THE LENS.
735
The fibres of the lens are somewhat flattened threads, about 3-^^th of an
inch wide, and are directed over the edge of the lens from the planes on one
surface to those on the other. In their course between the opposite surfaces,
no fibre passes from pole to pole, but the fibres beginning in the pole or
centre of one surface terminate in the end of a plane on the opposite sur-
face, and vice versa ; the intervening fibres passing to their corresponding
places between. Some of the superficial fibres possess transparent nuclei, at
nearly regular intervals. In the more superficial fibres of the growing lens
the nuclei occupy very regularly the equatorial part. At their ends,
where the fibres meet the planes, they are soft and indistinct ; and at the
Fig. 486.— MAGNIFIED VIEW OF THE FIBRES
OF THE CRYSTALLINE LENS.
A, longitudinal view of the fibres of the
lens from the ox, showing the serrated edges.
B, transverse section of the fibres of the lens
from the human eye (from Kolliker). C,
longitudinal view of a few of the fibres from
the equatorial region of the human lens
(from Henle). ^ The most of the fibres
are seen edgeways, and, towards 1, present the
swellings and nuclei of the "nuclear zone ;"
at 2, the flattened sides of two fibres are
middle part, where they are placed
on the margin of the lens, they are
widest and best marked. The fibres
are six-sided prisms, flattened in the
plane of the lamina in which they lie.
The edges are bevelled and sinuous ;
they are very regularly toothed at the
edges in fishes and some other animals
Fig. 487.
Fig. 486.
Fig. 487. — CELLS CONNECTING THE LENS WITH
ITS CAPSULE (from Bowman). —•
for more perfect junction with those in the same plane ; but in man and
mammals, the edge is only slightly jagged or irregularly serrated.
Changes in the lens by age. — In the foetus, the lens is nearly spherical : it
has a slightly reddish colour, is not perfectly transparent, and is softer, and
more readily broken down than at a more advanced age.
736 THE EYE.
In the adult, the anterior surface of the lens becomes more obviously less
convex than the posterior ; and the substance of the lens is firmer, colour-
less, and transparent.
o
Fig. 488. Fig. 488. — SIDE VIEWS OF THE LENS AT DIFFERENT AGES.
h C a, at birth with the deepest convexity ; 6, in adult life
with medium convexity ; c, in old age with considerable
flattening of the curvatures.
In old age, it is more flattened on both sur-
faces ; it assumes a yellowish or amber tinge, and
is apt to lose its transparency as it gradually increases in toughness and
specific gravity.
SUSPENSORY LIGAMENT OF THE LENS AND CANAL OF PETIT.
The suspensory ligament of the lens — Retzius — (Zonula of Zinn) is a
slender but tolerably firm transparent membrane, which, attached to the
fore part of the capsule of the lens close to its circumference, passes out-
wards to join the hyaloid membrane of the vitreous humour at its most
anterior convex part, opposite the ora serrata of the retina, and assists in
retaining the lens in its place. On the anterior surface small streaks of
pigment are observable after its separation from the other membranes, and
when this pigment is removed by washing, small but regular folds — processus
ciliares zonulse — come into view near the lens ; these are plaits in the
membrane, and are received into the intervals between the ciliary processes
of the choroid coat, into which they fit. Between the folds and the lens-
capsule is a slight interval free from plaits, which forms part of the boundary
of the posterior aqueous chamber. The posterior surface is turned towards
the hyaloid membrane, from which it is separated near the lens by a space
named the canal of Petit.
The suspensory ligament has chemical properties similar to those of the
capsule of the lens, but in it parallel or slightly radiating longitudinal fibres
may be recognised, which are stiff, elastic, and pale, resembling those of
elastic tissue, being less pliable, and less acted on by acetic acid than those
of connective tissue.
Fig. 489. Fig. 489.— VIEW FROM BEFORE OF THE CANAL OF PETIT
INFLATED (from Sappey).
The anterior parts of the sclerotic, choroid, iris and cornea
having been removed, the remaining parts are viewed from
before, and the canal of Petit has been inflated with air
through an artificial opening. 1, front of the lens ; 2,
vitreous body ; 3, outer border of the canal of Petit ; 4, outer
part of the zonule of Zinn ; 5, appearance of sacculated
dilatations of the canal of Petit.
The canal of Petit is the interval surrounding
the edge of the lens-capsule, bounded in front by the suspensory liga-
ment, and behind by the hyaloid membrane. Its width is about ^th of
an inch. On blowing air into it through an opening in the anterior
boundary, the plaits of the suspensory ligament on its front are distended,
and the canal presents a sacculated appearance.
DEVELOPMENT OF THE EYE.
737
AQUEOUS HUMOUR AND ITS CHAMBER.
The aqueous humour fills the space in the fore part of the eyeball, be-
tween the cornea and the capsule of the lens with its suspensory ligament.
The iris, resting in part upon the lens, divides the aqueous chamber partially
into two. The aqueous humour differs little from water in its physical cha-
racters ; but it contains a small quantity of some solid matter, chiefly chlo-
ride of sodium, dissolved in it.
The chambers, into which the space containing the aqueous humour is di-
vided by the iris, are named respectively the anterior and posterior. This
subdivision is incomplete in the adult, but in the foetus before the seventh
month it is completed by means of the inembrana pupillaris, which by its
union with the margin of the pupil closes the aperture of communication be-
tween the two chambers.
The anterior chamber is limited in front by the cornea and behind by the
iris, while opposite the pupil it is bounded by the capsule of the lens.
The posterior chamber was originally so named in the belief that a free
space intervened between the iris and the capsule of the lens. It is now,
however, well ascertained by observations on the living eye, and by sections
made in the frozen state, that the pupillary margin and part of the posterior
surface of the iris are in contact with the capsule of the lens ; and the term
posterior chamber can therefore be employed only to indicate the want of
continuity between those opposed structures, where no space actually inter-
venes, and to the angular interval existing at the circumference between the
ciliary processes, the iris, and the suspensory ligament.
DEVELOPMENT OF THE EYE.
The eyes begin to be developed at a very early period, in the form of two hollow
processes projecting one from each side of the first primary cerebral vesicle. Each
process becomes converted into a flask-shaped vesicle, called the primary optic vesicle,
which communicates by a hollow pedicle with the base of the posterior division of the
first primary cerebral vesicle. (See p. 578, and fig. 386 B.) According to the obser-
vations of Remak on the chick, the pedicles, originally separate, come together, and
their cavities temporarily communicate,— a condition which may explain the forma-
tion of the optic commissure. The primary optic vesicle comes into contact at its
extremity with the cuticle, which somewhat later becomes invaginated at this point,
and forms a small pouch pressing inwards on the optic vesicle ; the aperture of this
Fig. 490. — LONGITUDINAL SECTION
OP THE PRIMARY OPTIC VESICLE
IN THE CHICK MAGNIFIED (from
Remak).
A, from an embryo of sixty-five
hours ; B, a few hours later ; C,
of the fourth day ; c, the corneous
layer or epidermis, presenting in
A, the open depression for the
lens, which is closed in B and C ;
I, the lens-follicle and lens; pr,
the primary optic vesicle ; in A
and B, the pedicle is shown ; in C,
the section being to the side of the palicle, the latter is not shown; v,
ocular vesicle and vitreous humour.
the secondary
pouch becomes constricted and closed, and the pouch is soon converted into a shut
sac, within which the contents subsequently becoming solid form the lens and its
capsule. After the lens has been separated from the cuticle, the deeper tissue sends a
o C
738
THE EYE.
projection from below upwards between the lens and the optic vesicle, in such a
manner as to invaginate the superficial and lower walls of the vesicle, pressing them
upwards and inwards on the superior and deep walls, and giving them the form of a
cup imperfect below, the secondary optic vesicle. The involution gives rise to the
(Fig. 491. — DIAGRAMMATIC SKETCH OP A
VERTICAL LONGITUDINAL SECTION
THROUGH THE EYEBALL OP A HUMAN
FCETUS OP FOUR WEEKS (after Kolli-
ker). 122
The section is a little to the side so as to
avoid passing through the ocular cleft, c,
the cuticle, where it becomes later the
cornea; I, the lens; op, optic nerve
formed by the pedicle of the primary optic
vesicle ; vp, primary medullary cavity or
optic vesicle ; p, the pigment-layer of the
choroid coat of the outer wall ; r, the
inner wall forming the retina ; vs, secon-
dary optic vesicle containing the rudiment
of the vitreous humour.
cavity in which the vitreous humour is formed ; and, the forepart of the optic nerve
participating in the imagination, it is by this means that the central artery of the
retina is introduced into the nerve and the eyeball, being, as it were, folded within
them. The deficiency in the wall of the cup of the secondary vesicle inferiorly is
Fig. 492.
Fig. 492.— TRANSVERSE VERTICAL SECTION OF THE
EYEBALL OP A HUMAN EMBRYO OP FOUR WEEKS
(from Kolliker). *£-»
The anterior half of the section is represented.
pr, the remains of the cavity of the primary optic
vesicle ; p, the inner part of the outer layer, form-
ing the choroidal pigment; r, the thickened inner
part giving rise to the columnar and other struc-
tures of the retina ; v, the commencing vitreous
hiimour within the secondary optic vesicle ; v', the
ocular cleft through which the loop of the central
blood-vessel, a, projects from below ; lt the lens
with a central cavity.
gradually filled up by the growing downwards of the edges, until only a cleft is left,
which is discernible for a considerable time, and has been named the ocular cleft. The
history of this cleft is of interest in connection with congenital fissure of the iris
(coloboma iridis) and the accompanying condition of the choroid membrane. Some
difference of opinion exists with regard to the subsequent history of the walls of the
secondary vesicle, but the opinion of Kolliker appears to be well founded, that the
invaginated layer forms the retina, and the outer part the pigmentary epithelium
of the choroid. Thus the elements of Jacob's membrane and the hexagonal cells of
the choroid may be regarded as originally continuous, forming together the epithelial
lining of the cavity of the primary vesicle ; and the development of nervous tissue
underneath Jacob's membrane, while none exist beneath the choroidal layer, is a
circumstance which may be looked upon as analogous to the absence of nervous tissue
from various parts of the walls of the cerebral vesicles. The sclerotic coat and
cornea are formed from the surrounding tissue external to the parts of the eye which
they enclose ; and, according to Kolliker, the vascular part of the choroid is of later
formation. Still later, in the second month of foetal life, the iris begins to be formed
DEVELOPMENT OF THE EYE.
as a septum projecting inwards from the forepart of the choroid coat, between the lens
and the cornea.
Fig. 493.
pa-J,
Fig. 493. — VERTICAL LONGITUDINAL SECTION
OP THE EYE OF AN EMBRYO CALF (from
Kolliker). «
c, the cornea ; cc, conjunctiva of the cornea ;
I, the lens ; y, vitreous humour ; r, retina ;
p, pigment-layer of the choroid ; s c, com*
mencement of the sclerotic and choroid coats;
m, superior and inferior recti muscles ; pa,
folds of integument forming the commence-
ment of the upper and lower eyelids.
The crystalline lens in the foetus is sur-
rounded by a highly vascular tunic, supplied
by a branch of the central artery of the
retina, which passes forwards in the axis of
the globe, and breaks up at the back of the
lens into a brush of rapidly subdividing
branches. The forepart of this tunic, ad-
herent to the pupillary margin of the iris,
forms the pupillary membrane by which
the aperture of the pupil is closed. The
whole tunic, however, together with the artery which supplies it, becomes atrophied,
and is lost sight of before birth in the human subject, although in some animals it
remains for a few days after. According to Kolliker, the anterior chamber is formed
m sc
Fig. 494.
Fig. 494.— BLOODYESSELS OF THE CAP-
SULO-PtJPILLARY MEMBRANE OF A
NKW-EORN KITTEN, MAGNIFIED (from
Kolliker).
The drawing is taken from a prepara-
tion injected by Tiersch, and shows in
the central part the convergence of the
network of vessels in the pupillary
membrane.
only a short time before birth by the
intervention of the aqueous humour be-
tween the iris and cornea.
The eyelids make their appearance
as folds of integument, subsequently to
the formation of the globe. AY hen
they have met together in front of
the eye, their edges become closely
glued together • and they again open
before birth.
The lachrymal canal may be regarded as a persistently open part of the fissure
between the lateral frontal process and maxillary lobe of the embryo (See p 65 and
fig. 56 B, 4, 6.)
3 c 2
740 THE EAR.
THE EAR.
THE organ of hearing is divisible into three parts : the external ear, the
tympanum or middle ear, and the labyrinth or internal ear. The first two
of these are to be considered as accessories or appendages to the third, \\hich
is the sentient portion of the organ.
Fig. 495.
Fig. 495. — DIAGRAMMATIC VIEW FROM BEFORE OF THE PARTS COMPOSING THE ORGAN OF
HEARING OF THE LEFT SIDE (after Arnold, and from nature).
The temporal bone of the left side, with the accompanying soft parts, has been
detached from the head, and a section has been carried through it transversely so as to
remove the front of the meatus externus, half the tympanic membrane, the upper and
anterior wall of the tympanum and Eustachian tube. The meatus internus has also been
opened, and the bony labyrinth exposed by the removal of the surrounding parts of the
petrous bone. 1, the pinna and lobe ; 2, 2', meatus externus ; 2', membrana tympani ;
3, cavity of the tympanum ; IV, its opening backwards into the mastoid cells ; between
3 and 3', the chain of small bones ; 4, Eustachian tube ; 5, meatus internus containing
the facial (uppermost) and the auditory nerves ; 6, placed on the vestibule of the laby-
rinth above the fenestra ovalis ; a, apex of the petrous bone ; I, internal carotid artery ;
c, styloid process; d, facial nerve issuing from the stylo-mastoid foramen; e, mastoid
process ; /, squamous part of the bone covered by integument, &c.
THE EXTERNAL EAR.
In the external ear are included the pinna, — the part of the outer ear which
projects from the side of the head ; together with the meatus or passage which
leads thence to the tympanum, and is closed at its inner extremity by a
membrane (membrana tympani) interposed between it and the middle ear.
THE PINNA.
Superficial configuration. — The general form of the pinna or auricle is con-
cave, as seen from the outside, to fit it for collecting and concentrating the
undulations of sound ; it is thrown into various elevations and hollows, to
which distinct names have been given. The largest and deepest concavity,
STEUCTUEE OF THE PIXXA.
741
a little below the centre of the organ, is called the concha ; it surrounds the
entrance to the external auditory ineatus, and is unequally divided at its
upper part by a ridge, which is the beginning of the helix. In front of
the concha, and projecting backwards over the meatus auditorius, is a
conical prominence, the tragus, covered usually with hairs. Behind this,
and separated from it by a deep notch (incisura intertragica), is another
smaller elevation, the antitragus. Beneath the antitragus, and forming the
lower end of the auricle, is the lobule, which is devoid of the firmness and
elasticity that characterise the rest of the pinna. The thinner and larger
portion of the pinna is bounded by a prominent and incurved margin, the
helix, which, springing above and rather within the tragus, from the hollow
Fig. 496.— OUTER SURFACE OF THE PINNA OF THE EIGHT
AURICLE. |
1, helix ; 2, fossa of the helix ; 3, antihelix ; 4, fossa
of the antihelix ; 5, antitragus ; 6, tragus ; 7, concha ;
8, lobule.
Fu
\
of the concha, surrounds the upper and posterior
margin of the auricle, and gradually loses itself in
the back part of the lobule. Within the helix is
another curved ridge, the antihelix, which, begin-
ning below at the antitragus, sweeps round the hol-
low of the concha, forming the posterior boundary
of that concavity, and is divided superiorly into
two diverging ridges. Between the helix and the
antihelix is a narrow curved groove, the fossa of
the helix (fossa iunominata, scaphoid ea) ; and in
the fork of the antihelix is a somewhat triangular
depression, the fossa of the antihelix (fossa triaugu-
laris vel ovalis).
Structure. — The pinna consists of a thin plat 3 of cartilage and of integu-
ment, with a certain amount of adipose tissue. It presents also several liga-
ments and small muscles of minor importance.
The skin of the, pinna is thin, cbsely adherent to the cartilage, and con-
tains sebaceous follicles, which are most abundant in the hollows of the con-
cha and scaphoid fossa.
The cartilage presents all the inequalities of surface already described as
apparent on the outer surface of the pinna ; and on its cranial surface exhi-
bits prominences the reverse of the concha and the fossa of the helix, while
between these is a depression in the situation of the antihelix. This cartilage
is not confined to the pinna, but enters likewise into the construction of the
outer part of the external auditory canal. When dissected separate from
other structures, it is seen to be attached by fibrous tissue to the rough and
prominent margin of the external auditory meatus of the temporal bone.
The tubular part is cleft in front from between the tragns and fore part of
the helix inwards to the bone, the deficiency being filled with fibrous inem-
"brane ; thus the cartilage may be said to be a plat^, a part of which assumes
the tubular form by being folded so as to bring the upper margin, which lies
in front of the tube of the ear, nearly into contact with the lower part,
which being coiled inwards upon itself forms the upper border of the tragus.
Following the free border of the plate backwards beneath the meatus, it is
seen to pass round the lower margin of the concha, and to form the promi-
nences of the tragus and antitragus, while the cartilage is absent altogether
742
THE EAR.
from the lobule, which contains only fat and tough connective tissue.
Behind the antitragus is a deep notch, separating it from the cartilage of the
helix, which here forms a tail-like process descending towards the lobule. At
the fore part of the pinna, opposite the first bend of the helix, is a small
conical projection of the cartilage, called the process of the, helix, to which
the anterior ligament is attached. Behind this process is a short vertical
slit in the helix ; and on the surface of the tragus is a similar but somewhat
longer fissure. A deep fissure passes back between the commencement of
the helix and the tube of the ear, and another passing outwards and
backwards from the deep end of the longitudinal cleft separates the part
forming the tragus from the rest of the tube, so that the tube is continuous
with the pinna only by means of a narrow isthmus. One or two other
irregular gaps or fissures partially divide the cartilaginous tube transversely,
and the whole of these deficiencies are termed fissures of Santorini. The
substance of the cartilage is very pliable, and is covered by a firm fibrous
perichondrium.
Of the ligaments of the pinna, the most important are two, which assist
in attaching it to the side of the head. The anterior ligament, broad and
strong, extends from the process of the helix to the root of the zygoma.
The posterior ligament fixes the back of the auricle (opposite the concha) to
the outer surface of the mastoid process of the temporal bone. A few fibres
attach the tragus also to the root of the zygoma. Ligarnentous fibres are
likewise placed across the fissures and intervals left in the cartilage.
Of the muscles of the pinna, those which are attached by one end to the
side of the head, and move the pinoa as a whole, have been already des-
cribed (p. 170) : there remain to be examined several smaller muscles, com-
posed of thin layers of pale fibres, which extend from one part of the pinna
to another, and may be named the special muscles of the organ. Six small
muscles are distinguished ; four being placed on the outer and two on the
inner or deep surface of the pinna.
The smaller muscle of the helix (m. minor helicis) is a small bundle of
oblique fibres, lying over, and firmly attached to, that portion of the helix
which springs from the
Fig. 497 Fig. 498. bottom of the concha.
Fig. 497. — CARTILAGE OF THE
PlNNA EXPOSED, WITH THE
MUSCLES ON ITS OUTER SUR-
FACE.
] , musculus helicis minor ;
2, m. helicis major ; 3, tra-
gicus ; 4, antitragicus.
Fig. 498. — INNER SURFACE OF
THE CARTILAGE OF THE
PINNA WITH THE SMALL
MUSCLES ATTACHED.
5, transversus auriculse
muscle ; 6, obliquus auriculas
muscle.
The greater muscle of the helix (m. major helicis) lies vertically along the
anterior margin of the pinna. By its lower end it is attached to the process
of the helix j and above, its fibres terminate opposite the point at which the
ridge of the helix turns backwards.
EXTERNAL AUDITORY CANAL. 743
The muscle of the tragus (m. tragicus) is a flat bundle of short fibres
covering the outer surface of the tragus : its direction is nearly vertical.
The muscle of the antitragus (in. autitragicus) is placed obliquely over the
antitragus and behind the lower part of the antihelix. It is fixed at one
end to the antitragus, from which point its fibres ascend to be inserted into
the tail-like extremity 'of the helix, above and behind the lobule.
The transverse muscle (m. transversus auriculas) lies on the inner or cranial
surface of the pinna, and consists of radiating fibres which extend from the
back of the concha to the prominence which corresponds with the groove of
the helix.
The oblique muscle (Tod) consists of a few fibres stretching from the back
of the concha to the convexity directly above it, across the back of the
inferior branch of the antihelix, and near the fibres of the transverse muscle.
Arteries r>f the pinna. — The posterior auricular artery, a branch from the external
carotid, is distributed chiefly on the posterior or inner surface, but sends small branches •
round and through the cartilage to ramify on the outer surface of the pinna. Besides
this artery, the auricle receives others, the anterior auricular from the temporal in
front, and a small artery from the occipital behind.
The vei)is correspond much in their course with the arteries. They join the tem-
poral vein, and their blood is returned therefore through the external jugular.
Nerves of the pinna. — The great auricular nerve (p. 638), from the cervical plexus, sup-
plies the greater part of the back of the auricle, and sends small filaments with the pos-
terior auricular artery to the outer surface of the lobule and the part of the ear above it.
The posterior auricular nerve, derived from the facial (p. 612), after communicating with
the auricular branch of the pneumogastric, ramifies on the back of the ear and supplies
the retrahent muscle. The upper muscles of the auricle receive their supply from the
temporal branches of the same nerve. The auriculo-temporal branch of the third
division of the fifth nerve (p. 606) gives filaments chiefly to the outer and anterior
surface of the pinna.
THE EXTERNAL AUDITORY CANAL.
The external auditory canal (meatus auditorius externus) extends from
the bottom of the concha to the membrane of the tympanum, and serves to
convey to the middle chamber of the ear the vibrations of sound collected
by the auricle. The canal is about one inch and a quarter in length. In
Fig. 499. — VIEW OP THE LOWER HALF OF THE Fig. 499.
AURICLE AND MEATUS IN THE LEFT EAR
DIVIDED BY A HORIZONTAL SECTION (after
Sommerring).
1 and 2, cut surfaces of the bony part of the
meatus ; 3, cut surface of the cartilage of the
pinna ; 4, external meatus with the openings of
numerous ceruininous glands indicated ; 5, lobule ;
6, membrane of the tympanum j 7, dura mater
lining the skull.
its inward course it is inclined somewhat
forwards ; and it presents likewise a dis-
tinct vertical curve, being directed at fir^t
somewhat upwards, and afterwards turning
somewhat abruptly over a convexity of
the osseous part of its floor, and dipping
downwards to its termination, — a change of direction which must be
borne in mind by the surgeon in introducing specula into the ear. The
7-H THE EAR.
calibre of the passage is smallest about the middle. The outer opening
is largest from above downwards, but the tympanic end of the tube
is slightly widest in the transverse direction. At the inner extremity the
tube is terminated by the membrana tympani, which is placed obliquely,
with the inferior margin inclined towards the mesial plane, and thus the
floor of the meatus is longer than its roof.
The meatus is composed of a tube partly cartilaginous and partly osseous,
and is lined by a prolongation of the skin of the pinna.
The cartilaginous part of the meatus forms somewhat less than half the
length of the passage. It is formed by the deep part of the cartilage of the
pinna, which has been already described.
The osseous portion of the meatus is a little longer and rather narrower
than the cartilaginous part. At its inner end it presents a narrow groove,
which extends round the sides and floor of the meatus, but is deficient
above ; into this the margin of the membrana tympani is inserted.
The skin of the meatus is continuous with that covering the pinna, but is
very thin, aod becomes gradually thinner towards the bottom of the pas-
sage. In the osseous part of the canal it adheres very closely to the
periosteum ; and at the bottom of the tube this lining is stretched over the
surface of the membrana tympani, forming the outer layer of that struc-
ture. After maceration in water, or when decomposition is advanced, the
epidermic lining of the passage may be separated and drawn out entire, and
then ib appears as a small tube closed at one end somewhat like the finger
of a glove. Towards the outer part the skin possesses flue hairs and seba-
ceous glands ; and in the thick subdermic tissue over the cartilage are many
small oval glands of a brownish-yellow colour, agreeing in form and struc-
ture with the sweat glands. The cerumen or ear-wax is secreted by these
glands, glandulce ceruminosce, and their numerous openings may be seen to
perforate the skin of the meatus. These accessory parts are absent over the
bony part of the tube.
Vessels and nerves. — The external auditory meatus is supplied with arteries from
the posterior auricular, internal maxillary and temporal arteries; and with nerves
chiefly from the temporo-auricular branch of the fifth nerve.
State in the infant. — The auditory passage is in a very rudimentary state in the
infant, for the osseous part begins to grow out of the tympanic bone only at the period
of birth (p. 68), and thus the internal and middle parts of the ear are brought much
closer to the surface than in the adult.
THE MIDDLE EAR OR TYMPANUM.
The tympanum or drum, the middle chamber of the ear, is a narrow
irregular cavity in the substance of the temporal bone, placed between the
inner end of the external auditory canal and the labyrinth. It receives the
atmospheric air from the pharynx through the Eustachiau tube, and con-
tains a chain of small bones, by means of which the vibrations communicated
from without to the membrana tympani are in part conveyed across the
cavity to the sentient part of the internal ear, and by which also pressure
is maintained on the contents of the internal ear, varying in amount accord-
ing to the tension of the membrana tympani. The tympanum contains
likewise minute muscles and ligaments, which belong to the bones referred
to, as well as some nerves which end within this cavity, or pass through it to
other parts.
The cavity of the tympanum may be considered as presenting for con-
CAVITY AND MEMBRANE OF THE TYMPANUM. 745
sideration a roof and a floor, an outer and an inner wall, and an anterior
and a posterior boundary.
The roof of the tympanum is formed by a thin plate of bone, which may
be easily broken through so as to obtain a view of the tympanic cavity from
above ; it is situated on the upper surface of the petrous portion of the
temporal bone, near the angle of union with the squamous portion, from
which in its development it is derived.
The floor is narrow, in consequence of the outer and inner boundaries
being inclined towards each other.
The outer wall is mainly formed by a thin semitransparent membrane —
mernbrana tympani, which closes the inner end of the external auditory
meatus ; and, to a small extent, by bone. Immediately in front of the ring
of bone into which the membrana tympani is inserted, is the inner extremity
of the fissure of G laser, which gives passage to the laxator tympani muscle,
and attachment to the processus gracilis of the malleus. Close to the back of
this fissure is the opening of a small canal (named by Cruveilhier the canal
of Huguier), through which the chorda tympani nerve usually escapes from
the cavity of the tympanum and the skull.
Fig. 500.— MEMBRANA TYMPANI Ficr 500
AS SEEN FROM THE OUTER
AND INNER SIDE.
A, the outer surface ; B, the
inner ; in the latter the small
bones are seen adherent to the
membrane and adjacent parts of
the temporal bone ; in A,- the
shaded part indicates the small
bones as partially seen through
the membrane ; 1, membrana
tympani ; 2, malleus ; 3, stapes ;
4, incus.
The membrana tympani is a nearly circular disc, slightly concave on its
outer surface. It is inserted into the groove already noticed at the end of
the meatus externus, and so obliquely that the membrane inclines towards
the anterior and lower part of the canal at an angle of about 45°. The
handle of the malleus, one of the small bones of the tympanum, descends
between the middle and inner layers of the membrana tympani to a little
below the centre, where it is firmly fixed ; and, as the direction of this
process of the bone is slightly inwards, the outer surface of the mem-
brane is thereby rendered concave, being held inwards in the shape of a
shallow cone.
Though very thin, the membrana tympani is composed of three distinct
structures. A prolongation of the skin of the external meatus forms the
outer layer ; the mucous membrane lining the cavity of the tympanum
furnishes an inner layer ; and between those two is the proper substance of
the membrane, made up of fine fibrous and elastic tissues with vessels and
nerves. The greater number of the fibres radiate from near the centre at
the attachment of the handle of the malleus ; but close to the circumfer-
ence are some circular fibres, which form a dense, almost ligamentous ring.
The inner watt of the tympanum, which separates it from the internal ear,
is very uneven, presenting several elevations and foramina. Near its upper
part is an ovoid, or nearly kidney-shaped opening — fenestra ovalis, which
leads into the cavity of the vestibule. This opening, the long diameter of
746
THE EAR.
which is from before backwards, with a slight inclination downwards in
front, is occupied in the recent state by the base of the stapes, and the
annular ligament connected with that process of bone. Above the fenestra
ovalis, and between it and the roof of the tympanum, a ridge indicates
the position of the aqueduct of Fallopius, as it passes backwards, contain-
ing the portio dura of the seventh nerve. Below it is a larger and more
rounded elevation, caused by the projection outwards of the first turn of
the cochlea, and named the promontory, or tuber cochleae ; it is marked by
grooves, in which lie the nerves of the tympanic plexus.
Fig. 501.
Fig. 501. — INNER WALL OP THE OSSEOUS TYMPANUM AS EXPOSED BY A LONGITUDINAL
SECTION OP THE PETROUS AND MASTOID BONE (from Gordon).
1, opening of the tympanum into the inastoid cells ; 2, fenestra ovalis ; 3, fenestra
rotunda ; 4, promontory ; 5, aqueduct of Fallopius, or canal of the facial nerve ; 6,
junction of the canal for the chorda tympani with the aqueduct ; 7, processus cochleari-
formis ; 8, groove above it for the tensor tympani muscle ; 9, Eustachian tube j 10,
anterior orifice of the carotid canal.
Below and behind the promontory, and somewhat hidden by it, is a
slightly oval aperture named fenestra rotunda) which lies within a funnel-
shaped depression. In the macerated and dried bone the feuestra rotunda
opens into the scala tympani of the cochlea ; but, in the recent state it is
closed by a thin membrane.
The membrane closing the fenestra rotunda — the secondary membrane of
the tympanum (Scarpa) — is rather concave towards the tympanic cavity,
and is composed of three strata like the membrana tympani ; the middle
layer being fibrous, and the outer and inner derived from the membranes
lining the cavities between which it is interposed, viz., the tympanum and
the cochlea.
The posterior wall of the tympanum presents at its upper part one larger,
and several smaller openings, which lead into irregular cavities, the mastoid
cells, in the substance of the mastoid process of the temporal bone. These
cells communicate freely with one another, and are lined by mucous mem-
brane continuous with that which clothes the tympanum. Behind the
fenestra ovalis, and directed forwards, is a small conical eminence, called
the pyramid, or eminentia papillaris. Its apex is pierced by a foramen,
through which the tendon of the stapedius muscle emerges from a canal
which turns downwards in the posterior wall of the tympanum, and joins
obliquely the descending part of the aqueduct of Faliopius.
THE EUSTACHIAN TUBE. 747
The anterior extremity of the tympanum is narrowed by the gradual
descent of the roof, and is continued into the Eustachiau orifice. The
lower compartment of this orifice, lined with mucous membrane, forms the
commencement of the Eustachian tube ; the upper compartment, about
half an inch long, lodges the tensor tympaui muscle, and opens into the
tympanum immediately in front of the feuestra ovalis, surrounded by the
expanded and everted end of the cochleariforrn process, which separates it
from the lower compartment.
Fig. 502.
Fig. 502. — ANTERO-POSTEKIOR SECTION OP THK TEMPORAL BONE, SHOWING THE INNER
WALL OF THE TYMPANUM, wna THE EUSTACHIAN TUBE AND SMALL BONES IN THE
RECENT STATE (from Arnold).
1, styloid process ; 2, mastoid process ; 3, tipper part of the petrous bone ; 4, pharyn-
geal end of the Eustachian tube ; 5, its cartilage ; 6, its mucous surface ; 7, carotid
caual ; 8, fenestra rotunda; 9, malleus; 10, incus; 11, stapes; 12, pyramid and
stapedius muscle ; above 9, and behind 10, the suspensory ligaments of the malleus a ;d
incus are also seen.
The Eustachian tube is a canal, formed partly of bone, partly of cartilage
and membrane, which leads from the cavity of the tympanum to the upper
part of the pharynx. From the tympanum it is directed forwards and
inwards, with a little inclination downwards ; and its entire length is about
an inch and a half. The osseous division of the Eustachian tube, already
described in the Osteology, is placed in the angle of junction of the petrous
portion of the temporal bone with the squamous portion. The anterior
part of the tube is formed of a triangular piece of cartilage, the edges of
which are slightly curled round towards each other, leaving an interval at
the under side, in which the canal is completed by dense but pliable fibrous
membrane. Narrow behind, the tube gradually expands till it becomes
wide and trumpet-shaped in front ; and the anterior part is compressed
from side to side, and is fixed to the inner pterygoid process of the sphenoid
bone. The anterior opening is oval in form, and is placed obliquely at
the side and upper part of the pharynx, into which its prominent margin
projects behind the lower meatus of the nose, and above the level of the
hard palate. Through this aperture the mucous membrane of the pharynx
is continuous with that which lines the tympanum, and under certain,
conditions air passes into and out of that cavity.
748
THE EAB.
SMALL BONES OF THE EAR.
Three small bones (ossicula auditus) are contained in the uppr-r part of
the tympanum : of these, the outermost (malleus) is attached to the mein-
brana tympani j the innermost (stapes) is fixed in the fenestra oveilis ; and
Fig. 503.
Fig. 503. — BONES OP THE TYMPANUM
OF THE RIGHT SIDE (from Arnold), f
A, malleus; 1, its head; 2, the
handle ; 3, long or slender process ; 4,
short process ; B, incus ; 1, its body ;
2, the long process with the orbicular
process ; 3, short or posterior process ;
4, articular surface receiving the head
of the malleus; C, stapes; 1, hea4 ;
2, posterior crus ; 3, anterior crus ;
4, base ; C*, base of the stapes ; D,
the three bones in their natural con-
nection as seen from the outside ; a,
malleus ; b, incus ; c, stapes.
the third (incus), placed between
the other two, is connected to
both by articular surfaces. The
malleus and incus are placed in
nearly a vertical, the stapes in a
horizontal direction. They form
together an angular and jointed connecting rod between the membrana
tympani and the membrane which closes the fenestra ovalis.
The malleus, or hammer bone, consists of a central thicker portion, with
processes of different lengths. At the upper end of the bone is a rounded
head (capitulum), which presents internally and posteriorly an irregularly
oval surface covered with cartilage, for articulation with the incus. Below
the head is a constricted neck (cervix); and beneath this another slight
enlargement of the bone, to which the processes are attached. The handle
(manubrium) of the malleus is a tapering and slightly twisted process, com-
pressed from before backwards to near its point, where it is flattened in the
opposite direction : it descencre with a slight inclination forwards and in-
wards, and is received between the middle and inner layers of the membrana
tympani, to which it is closely attached. The long process (processus gra-
cilis) is a very slender spiculum of bone, which in the adult is usually broken
off in its removal from the tympanum, in consequence of its union with the
temporal bone ; it projects at nearly a right angle from the front of the
neck of the malleus, and extends thence obliquely downwards and forwards
to the Glasserian fissure. Its end is flattened and expanded, and is con-
nected by ligamentous fibres and by bone to the sides of the fissure. The
short process (processus brevis vel obtusus) is a low canical eminence spring-
ing from the root of the mauubrium, beneath the cervix, and projecting
outwards towards the upper part of the membrana tympani.
The incus has been compared to an anvil in form ; but it resembles per-
haps more nearly a tooth with two fangs widely separated. It consists of
a body and two processes. The body presents in front a concavo-convex
articular surface, which is directed upwards and forwards, and receives the
head of the malleus. The surfaces of the joint thus formed are tipped with
articular cartilage and enclosed by a synovial membrane. The shorter of
THE SMALL BOXES AND THEIR MUSCLES. 749
the two processes (crus breve) of the incus projects nearly horizontally
backwards from the upper part of the body of the bone, and is connected
by ligainentous fibres with the posterior wall of the tympanum near the
entrance of the rnastoid cells. The long process (crus longum) tapers
rather more gradually, and descends nearly vertically behind the handle of
the malleus : at its extremity it is bent inwards, and is suddenly narrowed
into a short neck ; and upon this is set a flattened rounded tubercle (pro-
cessus lenticularis), tipped with cartilage. This tubercle, which articulates
with the head of the stapes, was formerly, under the name of os orbiculare
sen lenticulare, described as a separate bone, which indeed it originally is in
childhood.
The stapes, the third and innermost bone of the ear, is in shape remark-
ably like a stirrup, and is composed of a head, a base, and two crura. The
head is directed outwards, and has on its end a slight depression, covered
with cartilage, which articulates with the lenticular process of the incus.
The base is a plate of bone placed in the fenestra ovalis, to the margin
of which it is fixed by ligameutous fibres. The form of the base is
irregularly oral, the upper margin being curved, while the lower is nearly
straight. The crura of the stapes diverge from a constricted part (neck)
of the bone, situated close to the head, and are attached to the outer
surface of the base near its extremities. The anterior cms is the shorter
and straighter of the two. The crura, with the base of the stapes, enclose
a small triangular or arched space, which in the recent state is occupied by
a thin membrane stretched across. A shallow groove runs round the opposed
surfaces of the bone, and into this the membrane is received.
LIGAMENTS AND MUSCLES OF THE TYMPANUM.
Ligaments. — In the articulations of the small bones of the ear with each
other, the connection is strengthened ly ligainentous fibres which cover the
synovial membranes.
The attachment of the bones of the ear to tho walls of the tympanum is
effected partly by the reflections of the mucous membrane lining that cavity,
but chiefly by muscles and by the following ligaments.
The suspensory ligament of the malleus consists of a small bundle of fibres,
which descends perpendicularly from the roof of the tympanum to the head
of the malleus. /
The incus is likewise suspended by a small ligament (the posterior liga-
ment of the incus), which extends from near the point of the short crus
directly backwards towards the posterior wall of the tympanum, where it is
attached near the entrance to the mastoid cells. •
Arnold describes an upper ligament which attaches the incus, near its articulation
with the malleus, to the roof of the tympanum. It lies close behind the suspensory
ligament of the malleus.
The annular or orbicular ligament of the stapes connects the base of the
bone to the margin of the fenestra ovalis, in which it is lodged.
Muscles. — There are three well-determined muscles of the tympanum.
Sornmerring describes four, and some authors a larger number ; but the
descriptions of these last muscles are not confirmed by later research. Of
the three muscles generally recognised, two are attached to the malleus, and
one to the stapes.
The tensor tympani (musculus internus mallei) is the largest of these
muscles. It consists of a tapering fleshy part, about half an inch in length,
and a slender tendon. The muscular fibres arise from the cartilaginous
750
THE EAR.
end of the Eustacliian tube and the adjoining surface of the sphenoid bone,
and from the sides of the upper compartment of the Eustachian orifice. In
Fig. 504.
Fig. 504. — VIEW OF THE CAVITY
OF THE EIGHT TYMPANUM FROM
ABOVE.
The cavity of the tympanum
and some parts of the labyrinth
have been exposed by a horizontal
section removing the upper part of
the temporal bone. 1, posterior
semicircular canal opened ; 2, the
cavity of the cochlea opened ; 3,
osseous part of the Eustachian
tube ; 4, head of the malleus ; 5,
incus ; 6, stapes, with its base set
in the fenestra ovalis ; 7, tensor
tympani muscle ; 8, stapedius.
this canal the muscle is con-
ducted nearly horizontally
backwards to the cavity of
the tympanum. Immediately
in front of the fenestra ovalis
the tendon of the muscle
bends at nearly a right angle
over the end of the processus
cochleariformis as through a
pulley, and, contained in a
fibrous sheath, passes out-
wards to be inserted into the
inner part of the handle of
the malleus, near its root.
The laxator tympani (laxator tympani major of Sommerring) is generally
believed to be distinctly muscular, but being partly concealed by a band of
fibrous tissue, doubts are still entertained by some observers as to whether
the structure known under this name is of a muscular or ligamentous nature.
Arising from the spinous process of the sphenoid bone, and slightly from
the cartilaginous part of the Eustachiau tube, it is directed backwards,
passes through the Glaserian fissure, and is inserted into the neck of the
malleus, just above the root of the processus gracilis.
The laxator tympani minor of Sommerring (posterior ligament of the malleus, Lincke)
is made up of reddish fibres, which are fixed at one end to the upper and back part of
the external auditory meatus, pass forwards and inwards between the middle and
inner layers of the membrana tympani, and are inserted into the outer border of the
handle of the malleus, and the short process near it. Sommerring. Icones Organi
Auditus Humani, 1801.
The stapedius is a very distinct muscle, but is hid within the bone, being
lodged in the descending part of the aqueductus Fallopii and in the hollow
of the pyramid. The tendon issues from the aperture at the apex of that
little elevation, and passing forwards, surrounded by a fibrous sheath, is
inserted into the neck of the stapes posteriorly, close to the articulation of
that bone with the lenticular process of the incus.
A very slender spine of bone has been found occasionally in the tendon of the
stapedius in man : and a similar piece of bone, though of a rounder shape, exists con-
ACTION OF THE MUSCLES.— LINING MEMBRANE. 751
stantly in the horse, the ox, and other animals. This circumstance is the more inte-
resting when it is remembered that cartilage occupies the position of the stapedius
before the muscle is developed. (P. 66 and fig. 528.)
Actions. — The malleus and incus move together round an axis extending backwards
from the attachment of the processus gracilis of the malleus in the Glasserian fissure
to the attachment of the short process of the incus posteriorly. The tendon of the
tensor tympani muscle passing from within to be inserted below that line, pulls the
handle of the malleus inwards, while the laxator tympani inserted above that line, by
pulling the head of the bone inwards, moves the handle outwards. The incus, moving
along with the malleus, pushes the stapes inwards towards the internal ear when the
membrana tympani is made tight, and withdraws that bone from the fenestra ovalis,
when the membrana tympaui is relaxed. But the cavity of the inner ear is full of
Fig. 505. — OUTLINE OF THE THREE SMALL BONES OF
THE LEFT EAR AS SEEN FROM BEFORE. f
This figure is designed to illustrate the effect of
the action of the tensor and laxator muscles of the
tympanic membrane in connection with their relation
to the axis of rotation of the malleus, a, a', the
malleus ; 6, the incus seen behind it ; c, the stapes ;
m, mf, the inner part of the meatus externus closevl
by the tympanic membrane, of which the posterior
half is represented ; the axis of rotation of the
malleus being supposed to pass through a point at
the root of the processus gracilis, g ; the line t, indi-
cates the direction and position of the tendon of the tensor tympani pulling the lower
part of the malleus inwards, the line /, that of the laxator tympani pulling inwards the
upper half of the malleus.
liquid ; and its walls are unyielding, except at the fenestra rotunda ; when, there-
fore, the stapes is pushed inwards the secondary membrane of the tympanum, which
blocks up the fenestra rotunda, must be made tense by pressure from within. The
attachment of the handle of the malleus, however, to the membrana tympani allows
greater freedom of movement to that process than is allowed to the stapes by the
ligament of its base, and when the movement of the stapes ceases, it is plain that the
malleus in any movement must rotate on the head of the incus; and hence, probably,
the necessity of a moveable articulation between tho*e bones. The action of the
stapedius muscle is obviously to draw the head of the stapes backwards, in doing which
the hinder end of the base of that bone will be pressed against the margin of the
fenestra ovalis, while the fore part will be withdrawn from the fenestra. The object
gained by this movement of the stapes is not sufficiently ascertained; but it is at least
evident that, if the stapes be pressed inwards by the incus in the action of the tensor
tympani, the stapedius muscle, if then contracted, will modify the pressure on the
internal ear. It is conceivable that the stapedius may thus protect the sensitive part
of the ear to a certain extent from excessive stimulation of the auditory nerve.
THE LINING MEMBRANE OF THE TYMPANUM.
The raucous membrane of the tympanum is continuous with that of the
pharynx through the Eustachian tube, and is further prolonged from the
tympanum backwards into the mastoid cells. Two folds which cross the
breadth of the cavity descend from the part of the membrane which lines
the roof. The anterior fold descends to turn round the tendon of the tensor
tympani muscle ; the posterior fold passes round the stapes. The malleus
and incus are invested by the lining of the outer wall of the cavity. The
mucous membrane which lines the cartilaginous part of the Eustachian tube
resembles much the membrane of the pharynx, with which it is immediately
continuous ; it is thick and vascular, and is covered by several layers of
laminar epithelium with vibratile cilia, and is provided with many simple
mucous glands which pour out a thick secretion : in the osseous part of the
752 THE EAR.
tube, however, this membrane becomes gradually thinner. In the tympa-
num and the mastoid cells it is paler, thinner and less vascular, and secretes
a less viscid, but yellowish fluid. The epithelium in the tympanic cavity is
also ciliated. The cilia, however, are usually absent from the part which
lines the meinbrana tympani (Kolliker, Handbuch, p. 691).
THE VESSELS AND NERVES OF THE TYMPANUM.
The arteries of the tympanum, though xery small, are numerous, and
are derived from several branches of the external, and from the internal
carotid.
The fore part of the cavity is supplied chiefly by the tympanic branch of the internal
maxillary (p. 356), which enters by the fissure of Glaser. The back part of the
cavity, including the mastoid cells, receives its arteries from the stylo-mastoid branch
of the posterior auricular aitery (p. 353), which is conducted to the tympanum by the
aqueduct of Fallopius. These two arteries form by their anastomosis a vascular circle
round the margin of the membrana tympani. The smaller arteries of tlie tympanum
are, the petrosal branch of the middle meningeal, which enters through the hiatus
Fallopii ; branches through the bone from the internal carotid artery, furnished from
that vessel whilst in the carotid canal; and occasionally a twig along the Eustacliian
tube from the ascending pharyngeal artery.
The veins of the tympanum pour their.contents through the middle meningeal and
pharyngeal veins, and through a plexus near the articulation of the lower jaw, into the
internal jugular vein.
Nerves. — The tympanum contains numerous nerves; for, besides those
which supply the parts of the middle ear, there are several which serve
merely to connect nerves of different origin.
The lining membrane of the tympanum is supplied by filaments from the
plexus (tympanic plexus), which occupies the shallow grooves on the inner
wall of the cavity, particularly on the surface of the promontory.
The tympanic plexus is formed by the communications between, 1st, the
tympanic branch (nerve of Jacobson) from the petrous ganglion of the glosso-
pharyugeal ; 2nd, & filament from the carotid plexus of the sympathetic ; 3rd,
a branch which joins the great superficial petrosal nerve, from the Vidian ;
4th and lastly, the small superficial petrosal nerve, from the otic ganglion.
FiS- 506- Fig. 506.— VIEW OP THE TYAIPANIO
PLEXUS OP NERVES (after Hirschfeld
and Leveille).
6, spheno-palatine ganglion ; 7, Vidian
nerve ; 8, great superficial petrosal
n?rve ; 9, carotid branch of the Vidian
nerve ; 10, part of the sixth nerve con-
nected by twigs with the sympathetic ;
11, superior cervical ganglion of the
sympathetic ; 12, carotid branch ; 13,
facial nerve ; 14, glosso-pharyngeal
nerve ; 15, nerve of Jacobsou ; 16, its
twig to the sympathetic ; 17, filament
to the fenestra rotunda ; 18, filament to
the Eustachian tube ; 19, filament to the
fenestra ovalis ; 20, union of external deep petrosal nerve with the lesser superficial
petrosal ; 21, internal deep petrosal twig uniting with the great superficial petrosal.
The nerve of Jacobson enters the tympanum by a small foramen near its floor,
which forms the upper end of a short canal in the petrous portion of the temporal
bone, beginning at the base of the skull between the carotid foramen and the jugular
THE INTERNAL EAR. OSSEOUS LABYRINTH.
753
fossa. The nerve from the carotid plexus is above and in front of this, and passes
through the bone directly from the carotid canal. The branch to the great superficial
petrosal nerve is lodged in a canal which opens on the inner wall of the tympanum in
front of the fenestra ovalis. The small superficial petrosal nerve also enters at the
fore part of the cavity beneath the canal for the tensor tympani.
Nerves to Muscles. — The tensor tympani muscle obtains its nerve from,
the otic ganglion (see fig. 410) ; the laxator tympani is said to be supplied
by the chorda tympani: and the stapedius is figured by Sommerriug as
receiving a filament from the facial nerve.
The chorda tympani is invested by a tubular reflection of the lining mem-
brane of the tympanum ; its course across the cavity has already been
described (p. 611).
THE INTERNAL EAR, OR LABYRINTH.
The inner, or sensory part of the organ of hearing, is contained in the
petrous portion of the temporal bone. It consists of a cavity — the osseous
labyrinth — hollowed out of the bone, and of the membranous labyrinth con-
tained within the osseous walls.
Fig. 507.
Fig. 507. — RIGHT BONY LABYRINTH, VIEWED
FROM THE OUTER SIDE (after Sb'mmer-
ring). ^
The specimen here represented is pre-
pared by separating piecemeal the looser
substance of the petrous bone from the dense
walls which immediately enclose the laby-
rinth. 1, the vestibule ; 2, fenestra ovalis ;
3, superior semicircular canal ; 4, horizontal
or external canal ; 5, posterior canal ; *, am-
pullae of the semicircular canals ; 6, first
turn of the cochlea ; 7, second turn ; 8,
apex ; 9, fenestra rotunda. The smaller
figure in outline below shows the natural
size.
The osseous labyrinth is incompletely
divided into three parts, named the
vestibule, the semicircular canals, and
the cochlea. They are lined throughout by a thin membrane, within which
there is a clear fluid named perilymph.
The membranous labyrinth is contained within the bony labyrinth, and,
being smaller than it, leaves a space between the two, occupied by the peri-
lymph just referred to. The membranous structure supports numerous
minute ramifications of the auditory nerve, and encloses a fluid named the
endolymph.
THE OSSEOUS LABYRINTH.
The vestibule forms a central chamber of the labyrinth, which communi-
cates in front with the cochlea, behind with the semicircular canals, on the
outer side with the cavity of the tympanum, and on the inner side with the
roeatus auditorius interims. The vestibule is irregularly ovoidal in ^hape
from before backwards, and is slightly flattened or compressed from without
3 D
751
THE EAR.
inwards : except in the last-mentioned direction, in which it is somewhat
smaller, it measures about -^th of an inch in diameter.
The outer wall which separates it from the cavity of the tympanum, is
perforated by the fenestra ovalis, which in the recent state is closed by the
base of the stapes and its annular ligament.
At the fore part of the inner wall is a small round pit, the fovea hemi-
spherica, pierced with many small holes, which serve to transmit branches of
the auditory nerve from the internal auditory meatus. This fossa is limited
behind by a vertical ridge named crista vestibuli or eminentia pyramidalis.
Behind the crest is the small oblique opening of a canal, the aqueduct of the
vestibule, which extends to the posterior surface of the bone, and transmits
a small vein in a tubular prolongation of membrane.
In the roof is an oval depression, placed somewhat transversely, fovea
hemi-elliptica, whose inner part is separated by the crest from the hemi-
spherical fossa.
At the back part of the vestibule are five round apertures, leading into
the semicircular canals : and at the lower and fore part of the cavity is a
larger opening, which communicates with the scala vestibuli of the cochlea —
apertura scalm vestibuli.
The semicircular canals are three bony tubes, situate above and behind
the vestibule, into which they open by five apertures, the contiguous ends of
Fig. 508.
Fig. 508. — VIEW OF THE INTERIOR OF THE
LEFT LABYRINTH (from Sommerring). ?i
The bony wall of the labyriuth is removed
superiorly and externally. 1, fovea hemi-
elliptica ; 2, fovea hemispherica ; 3, common
opening of the superior and posterior semi-
circular canals ; 4, opening of the aqueduct
of the vestibule ; 5, the superior, 6, the
posterior, and 7, the external semicircular
canals; 8, spiral tube of the cochlea (scala
tyropani) ; 9, opening of the aqueduct of the
cochlea ; 10, placed on the lamina spiralis
in the scala vestibuli.
two of the canals being joined. They
are unequal in length, but each tube
is bent so as to form about two-thirds of a circle ; and each presents, at one
end, a slightly dilated part, called the ampulla. The canals are compressed
laterally, and measure across about ^th of an inch ; but in the ampulla each
has a diameter of -j^-th of an inch.
The canals differ from one another in position with regard to the vestibule,
in direction, and in length. The superior semicircular canal is vertical and
transverse ; and, rising above any other part of the labyrinth, its place is
indicated by a smooth arched projection on the upper surface of the
bone. The ampullary end of this canal is the anterior, and opens by
a distinct orifice iuto the upper part of the vestibule ; whilst the oppo-
site extremity joins the non-dilated end of the posterior semicircular
canal, and opens by a common aperture with it into the back part of
the vestibule. The posterior semicircular canal, vertical and longitudinal
in direction, is the longest of the three tubes: its ampullary end is
placed at the lower and back part of the vestibule ; and the opposite
end joins in the common canal above described. The external semi-
THE OSSEOUS COCHLEA,
755
circular canal arches horizontally outwards, and opens by two distinct
orifices into the upper and back part of the vestibule. This canal is shorter
than either of the other two : its ampulla is at the outer end, just above the
fenestra ovalis.
Fig. 509.
Fig. 509. — VIEWS OF A CAST OP THE INTERIOR OP THE LABYRINTH (from Henle). f
Such casts may easily be marie in fusible metal, and give a very correct view of the
form of the different parts of the labyrmthic cavity. A, view of the left labyrinth from
the outer side ; B, the right labyrinth from the inner side ; C, the left labyrinth from
above ; s, the superior, p, the posterior, and e, the external semicircular canals ; a, their
several ampullae ; re, fovea hemi-elliptica of the vestibule ; rs, fovea hemispherica ; av,
aqueduct of the vestibule ; fo, fenestra ovalis ; fr, fenestra rotunda ; c, the coiled tube
of the cochlea ; c', the first part of the tube towards the base with the tractus forami-
nosus spiralis.
The cochlea is the most anterior division of the internal ear. When the
dense bony substance, in which it lies embedded, is picked away, the
cochlea presents the form of a blunt cone, the base of which is turned
towards the internal auditory meatus, whilst the apex is directed outwards,
with an inclination forwards and downwards, and is close to the canal for the
tensor tympani muscle. It measures about a quarter of an inch in length,
and the same in breadth at the base. The osseous part of the cochlea con-
sists of a gradually tapering spiral tube, the inner wall of which is formed
by the central column, or modiolus, round which it
winds, and which is partially divided along its whole
extent by a spiral lamina, projecting into it from the
modiolus. From this osseous spiral lamina membranous
structures are stretched across to the outer wall of the
tube, and thus are completely separated two passages
or scalee, oce on each side of the spiral lamina, which
communicate one with the other by only a small open-
ing, named helicotrema, placed at the apex of the
cochlea.
Fig. 510.— OSSEOUS LABYRINTH OF THE BARN-OWL (SiRix
FLAMMEA) (from Breschet). *
Fig. 510.
1, semicircular canals ; 2, vestibule ;
of a short straight tube.
cochlea in the form
That the cochlea is justly to be considered as an elongated tube, coiled
srirally on the modiolus, is illustrated by the simple pouch-like form of the
rudimentary cochlea of birds.
The spiral canal of the cochlea is about an inch and a half long, and
about the tenth of an inch in diameter in its widest part at the commence-
3 D 2
756 THE EAR.
ment. From this point the canal makes two turns and a half round the
central pillar (from left to right in the right ear, and in the opposite
direction in the left ear), and ends by an arched and closed extremity called
the cupola, which forms the apex of the cochlea. The first coil, being much
the widest in its curve and composed of the largest portion of the tube,
nearly hides the second turn from view ; and bulging somewhat into the
tympanum, forms the round elevation on the inner wall of that cavity called
the promontory.
Fig. 511.
Fig. 511. — DIAGRAMMATIC VIEW OF THE CANAL OF THE COCHLEA LAID OPEN, f
1, modiolus or central pillar; 2, placed on three turns of the lamina spiralis ; 3, scala
tympani ; 4, scala vestibuli.
Fig. 512. — VIEW OF THE OSSEOUS COCHLEA DIVIDED THROUGH THE MIDDLE
(from Arnold), f
. 1, central canal of the modiolus ; 2, lamina spiralis ossea ; 3, scala tympani ; 4, scala
vestibuli ; 5, porous substance of the modiolus near one of the sections of the canalis
spiralis modioli.
The modiolus (columella cochleae) forms the central pillar or axis round
which turn the spiral tube and the spiral lamina. It is much thickest
within the first turn of the cochlea, and rapidly diminishes in size in the
succeeding parts. The outer surface is dense, being, iu fact, composed of the
walls of the spiral tube ; but the centre is soft and spongy as far as the last
half coil, and is pierced by many small canals, for the passage of the nerves
and vessels to the lamina spiralis : one of these canals, larger than the rest
(canalis centralis modioli), runs from the base through the centre of the
modiolus.
The lamina spiralis ossea is a thin, flat plate, growing from and winding
round the modiolus, and projecting into the spiral tube, so as to divide it
partly into two. Its free margin, which gives attachment in the recent
state to the membranous septum, or zone, does not reach farther than about
half of the distance between the modiolus and the outer wall of the spiral
tube. The osseous lamina terminates close to the apex of the cochlea in a
hook-like process (hamulus), which partly bounds the helicotrema.
The lamina is thin and dense towards its free margin ; but near the
modiolus it is composed of two dense outer plates enclosing a more open
and spongy structure, in which are numerous small canals, continuous, but
running at right angles with the canals in the centre of the modiolus. In
these the nerves and vessels are lodged : they terminate on the inferior or
tympanic aspect of the lamina, and the line of their orifices forms the tractus
foraminosus spiralis. Winding round the modiolus, close to the lamina
spiralis, is a small canal, named by Rosenthal the canalis spiralis modioli.
The scalce in the osseous cochlea are two in number, distinguished as the
scala tympani and scala vestibuli.
THE MEMBRANOUS LABYRINTH. 757
The scala tympani, the portion of the tube on the basal side of the lamina
spiralis, commences at the fenestra rotunda, where in the recent state it is
separated from the tympanum by the secondary metnbrana tympani. Near
its commencement is the orifice of a small canal aqueductus cochleae,, which
extends downwards and inwards through the snbstance of the petrous part
of the temporal bone to near the jugular fossa, and transmits a small vein .
The surface of the spiral lamina which looks towards this scala is marked
with numerous transverse striae. The scala vestibuli is rather narrower than
the scala tympaui in the first turn of the cochlea ; it commences from the
cavity of the vestibule, and communicates, as already described, with the
scala tympani at the apex of the modiolus.
TJie lining membrane of the osseous labyrinth. — This is a thin membrane
(periosteum ?), which closely adheres to the whole inner surface of the
several parts of the labyrinthic cavity just described. It has no con-
tinuity with the lining membrane of the tympanum, being stretched
across the openings of the round and oval fenestrse. It is composed of
fibres of connective tissue. Its outer surface is rough, and adheres closely,
like periosteum, to the bone : the inner surface is pale and smooth, is
covered with a single layer of epithelium, like that of the arachnoid, and
secretes a thin, slightly albuminous or serous fluid. This secretion, known
as the liquor Cotunnii, or perilymph, separates the membranous from the
osseous labyrinth in the vestibule and semicircular canals, occupies the
cavities of the scala tympani and scala vestibuli in the cochlea, and is
continued into the aqueducts as far as the membrane lining these passages
remains pervious.
THE MEMBRANOUS LABYRINTH.
Within the osseous labyrinth, and separated from its lining membrane by
the perilymph, membranous structures exist in which the ultimate ramifi-
cations of the auditory nerve are spread. In the vestibule and semicircular
canals these structures have a general resemblance in form to the com-
plicated cavity in which they are contained. In the cochlea they complete
the septum between the scalse already mentioned, and enclose a third spiral
passage, the canalis membranacea, the existence of which has only been
discovered of late years. The liquid contained within the membranous
labyrinth is distinguished as endolymph.
VESTIBULE. — The membranous vestibule consists of two closely connected
sacs, and the parts by which they are united to the membranous semi-
circular canals and canal of the cochlea.
The larger of the two sacs, the common sinus or utricle, is of an oblong
form and slightly flattened from without inwards. It is lodged in tho
upper and back part of the osseous vestibule, occupying the fovea hemi-
elliptica. Opposite the crista vestibuli several small branches of the audi-
tory nerve enter from the foramina in the bone ; and here the walls of the
common sinus are thicker and more opaque than elsewhere. The extre-
mities of the membranous semicircular canals terminate in the cavity of
the common sinus. A small mass of calcareous particles, otoliths or oto*
conia, is lodged in the wall of the sac. These otoliths are crystals of
carbonate of lime, and are described as six-sided, and pointed at their extre-
mities. They are connected with the wall of the sac in a way not yet
clearly determined.
The smaller vestibular vesicle, the saccule, is more nearly spherical than
the common sinus, but, like it, is somewhat flattened. The saccule is situated
758 THE EAE.
in the lower and fore part of the cavity of the osseous vestibule, close to
the opening from the scala vestibuli of the cochlea, and is received into the
hollow of the fovea hemispherica, from the bottom of which many branches
of nerve enter. The sacculus appears to have a cavity distinct from that
of the utricle, but is filled with the like thin and clear fluid, endolymph, and
contains similar otoconia in its wall. It is prolonged below into a short
narrow duct, canalis reuniens, which opens abruptly into the membranous
canal of the cochlea.
Fig. 513.
A. B.
Fig. 513. — VIEWS OF THE INTERIOR OF THE RIGHT LABYRINTH WITH ITS MEMBRANOUS
PARTS AND NERVES (from Breschet). f
A, the outer wall of the osseous labyrinth in part removed so as to display the mem-
branous parts within. 1, commencement of the spiral tube of the cochlea ; 2, posterior
semicircular canal partially opened, showing its membranous canal and ampulla; 3,
external or horizontal canal entirely opened ; 4, superior canal ; 5, utriculus or common
sinus with its group of otoliths ; 6, saccule with its otoliths ; 7, placed on the lamina
spiralis in the commencement of the scala vestibuli ; 7', scala tyrapani ; 8, membranous
ampulla of the superior semicircular canal ; 9, ampulla of the horizontal, and 10, that
of the posterior semicircular canal.
B, membranous labyrinth and nervous twigs detached ; 1, facial nerve in the meatus
auditorius internus ; 2, anterior division of the auditory nerve giving branches to 5, 8,
and 9, the utricle and the ampullae of the superior and external canals ; 3, posterior
division of the auditory nerve, giving branches to the saccule ; 6, posterior ampulla, 10,
and cochlea, 4 ; 7, the united part of the superior and posterior canals ; 11, the posterior
extremity of the external canal.
SEMICIRCULAR CANALS. — The membranous semicircular canals are about
one third the diameter of the osseous tubes in which they are lodged, and
are dilated into ampullae within the ampullary enlargements of those tubes.
At the ampullae they are thicker and less translucent than in the rest of
their extent, and nearly fill their bony cases. That part of each ampulla
which is towards the concavity of the semicircle of the canal is free ; whilst
the opposite portion is flattened, receives branches of nerves and blood-
vessels, and presents on its inner surface a transverse projection, septum
transversum, which partly divides the cavity into two. The ampullae like-
wise contain otoliths in their epithelial lib ing.
Auditory nerve: vestibular division. — At the bottom of the meatus audi-
torius internus the auditory nerve divides into an anterior and a posterior
branch, which, broken up into minute filaments, pass through the perfora-
tions of the cribriform plate which separates the meatus from the internal
ear, and are distributed respectively to the cochlea and vestibule. In both
branches, as well as in the trunk, there are numerous nerve-cells, appa-
rently both with and without poles. The vestibular nerve divides into five
branches, which proceed respectively to the utricle, the saccule, and the
three ampullse of the semicircular canals : those for the utricle and the
MINUTE STRUCTURE OF MEMBRANOUS LABYRINTH. 759
superior and external semicircular canals enter the cavity in a group along
the crista vestibuli ; the fibrils for the sacculus enter the vestibule by a
smaller group of foramina, which are situated below those just described,
and open at the bottom of the fovea hemispherica ; the branch for the pos-
terior semicircular canal is long and slender, and traverses a small passage
Fig. 515.
Fig. 514.
•r
'"
Fig. 514. — TRANSVERSE SECTION OF ONE OP THE MEMBRANOUS SEMICIRCULAR CANALS
(from Kolliker). ^
This specimen is from the ear of the calf : a, external fibrous layer with interspersed
nuclei ; 6, homogeneous layer ; c, epithelial lining.
Fig. 515.— AMPULLA OF THE SUPERIOR AND EXTERNAL SEMICIRCULAR CANALS AND PART
OF THE COMMON SINUS SHOWING THE ARRANGEMENT OF THE NERVES (from Steifen-
sand) . %£-
1, membranous ampulla of the superior canal ; 2, that of the external canal ; 3, part
of the common sinus ; 4 and 5, fork-like swellings of the nerves at their ampullar dis-
tribution ; 6, twig of the auditory nerve spreading in the common sinus.
in the bone behind the foramina for the nerve of the sacculus. The nerves
of the ampullae enter the flattened or least prominent side of the ampullaa,
where they each form a forked swelling, which corresponds with the trans-
verse septum already described, in the interior of the dilatation. No
filaments have been fuund extending to any other parts of the semicircular
canals.
Microscopic structure. — The walls of the common sinus, sacculus and
membranous semicircular canals are in general semitransparent ; but they
are thicker and more opaque where nerves and vessels enter. On the
outer surface is a layer of minutely ramified blood-vessels and loose tissue,
which contains irregular pigment- cells : within this is a transparent layer,
faiutly fibrillated, and presenting elongated nuclei when acetic acid is added ;
lining the interior is an epithelial layer of polygonal nucleated cells.
The mode of ending of the nerves in the membranous substance of the
vestibule and semicircular canals is difficult to investigate, on account of
the minuteness and delicacy of the parts ; for this reason also observers
have had recourse in great measure to the examination of the vestibule
760
THE EAR.
and semicircular canals in fishes, in which they are of large size. The
subject still requires further research, but it appears to be pretty certain
from the observations of Reich, the successive papers of M. and F. E.
Schultze, and the corroborating observations of Kolliker, that the nerve
fibres break up in the transparent layer into minute ramifications, which
enter the epithelium and form between the epithelial cells spindle-shaped
nucleated bodies with elongated extremities. There have also been ob-
served long hair-like processes, fila acustica, projecting into the cavity,
beyond the epithelial surface of the ridge of the ampullse, and likewise
in the sacs ; and the actual continuity of these hairs with the nerve-
terminations has been in one instance observed by F. E. Schultze.
According to Lang the hairs are only the altered remains of a delicate cap
of tissue on the surface of the epithelium. — (Kolliker's Gewebelehre, 4th
ed., p. 694.)
Fig. 516.
Fig. 517.
Fig. 516.— LEFT COCHLEA OP A CHILD SOME WEEKS OLD, opened (from Reichert). a
The drawing was taken from a specimen which had been preserved in alcohol, and was
afterwards dried ; the section is made so as to show the lamina spiralis, scalas, and
cochlear canal in each of the three coils : the membranous spiral lamina is preserved,
but the appearances connected with the organ of Corti, &c., have been lost from drying.
/ r, fenestra rotunda with its membrane ; s t, scala tympani ; s v, scala vestibuli ; I s,
lamina spiralis ; ht hamulus ; c c, canalis cochleae ; d, opening of the aqueductus
cochleae
Fig. 517. — VERTICAL SECTION OF THE COCHLEA OF A FOETAL CALF (from Kolliker). f
In this specimen the external wall was ossified, but the modiolus and spiral lamina
were still cartilaginous ; the section shows in each part of the cochlear tube the two
scalaa with the intermediate canalis cochleae and lamina spiralis ; the radiating lines in
the modiolus indicate the passage of the auditory nerves towards the spiral lamina.
COCHLEA. — The membranous cochlea has the form of a three-sided
tube, the canalis membranacea, interposed between the scala vestibuli
and the scala tympani. The peripheral wall of this canal is formed by
part of the osseous cochlea, and on its other sides it is bounded by the
basilar membrane and membrane of Reissner respectively, while at its
inner angle is a structure named limbus laminae spiralis, and in its interior
resting on the basilar membrane, is the organ of Corti with the membrana
tectoria covering it. Each of these parts requires description.
The membrana basilaris, or lamina spiralis membranacea, is stretched
across from the free margin (labium tympanicum) of the osseous lamina to
MINUTE STRUCTURE OF THE COCHLEA. 761
the outer part of the spiral canal, lying in the same plane as the osseous
lamina, and attached peripherally through the medium of a thick structure,
the spiral ligament. It increases in breadth from the base to the apex of
the cochlea, while the osseous spiral lamina diminishes in breadth. Thus
in the first turn of the cochlea this membrane forms about half of the
breadth of the septum made by it and the osseous lamina ; but towards the
apex of the cochlea the proportion between the two parts is gradually
reversed, until, near the helicotrema, the membranous part is left almost
unsupported by any plate of bone.
Fig. 518.— SECTION THROUGH ONE Fig. 513.
OP THE COILS OP THE COCHLEA
(altered from Henle). ^
A, the section is made in a
specimen softened by immersion in
hydrochloric acid ; S T, scala tym-
pani ; S V, scala vestibuli ; C C,
canalis cochleae ; R, membrane of
Reissner forming its vestibular /Jt
wall ; I so, lamina spiralis ossea ;
1 1 s to I s p, lamina spiralis mem-
branacea ; I Is, limbus laminae
spiralis ; s s, sulcus spiralis ; n c,
twigs of cochlear nerve ; g s, gang-
lion spirale ; t, membrana tectoria;
6, membrana basilaris ; Co, organ
of Corti ; Isp, ligameutum spirale.
The limbus lamincz spiralis (denticulate lamina of Todd and Bowman)
is a thick periosteal development near the edge of the osseous spiral lamina
on the side which looks towards the vestibular scala. It makes a some-
what convex elevation, presenting externally a sharp margin which over-
hangs that to which the basilar membrane is attached, being separated
from it by a groove. The groove is termed sulcus spiralis, and the margins
labium vestibulare and labium tympanicum respectively. The membrane of
Reissner (membrana vestibularis) arises from the inner part of the limbus,
and extends outwards at a considerable angle with the osseous spiral
lamina.
The membrana tectoria (Claudius), or membrane of Corti (Kolliker), has
been variously described, but, according to the most recent researches, is
an elastic membrane attached on its one border close to the membrane of
.Reissner, and on the other by an extremely delicate portion to the peri-
pheral wall of the cochlea, a little above the membrana basilaris (Claudius
and Henle). It thus divides the canalis membrauacea into two parts : the
large part placed between it and the membrane of Reissner, and con-
taining endolymph ; the other, a narrow interval dividing it from the
membrana basilaris, and occupied by various cellular and rod-like structures
of a highly complicated description, which together are designated as the
organ of Corti.
The canalis membranacea, or ductus cochlearis, bounded in the manner
already described, presents a blind pointed extremity at the apex and
another at the base. That at the apex extends beyond the hamulus, fixed
to the wall of the cupola, and partly bounding the helicotrema ; that at
the base fits into the angle at the commencement of the osseous spiral
lamina in front of the floor of the vestibule. Near to this blind extremity
the canalis membranacea receives a small duct, canalis reuniens (Hensen),
762
THE EAK.
which is continued downwards from the saccule of the vestibule like the
neck of a flask, and enters the membranous canal abruptly nearly at a right
angle to it. Thus the cavity of the canalis membranacea is rendered con-
tinuous with that of the saccule.
Fig. 519. — THE LEFT LABYRINTH OF
A CHILD AT BIRTH, PARTIALLY
OPENED ON ITS OUTER SIDE TO SHOW
THE COMMENCEMENT OF THE MEM-
BRANOUS CANAL OF THE COCHLEA
(slightly altered after Reich ert). f
The external or horizontal canal has
been removed; cs, superior canal; cp,
posterior canal ; a s, membranous am-
pulla and tube of the superior canal
cut short ; a 7i, that of the external or
horizontal canal ; h, undilated end of
the horizontal canal in front of the
common opening of the superior and
posterior canals ; p s, united superior
and posterior canals ; u, utriculus ; s, eacculus ; c c, vestibular part or commencement
of the membranous canal of the cochlea ; c r canalis reuniens connecting it with the
sacculus ; c, cochlea.
It is necessary to explain that, although the canalis membranacea was described by
Reissner so long ago as in 1851, yet, owing to some confusion having arisen between
the membrane of .Reissner and the membrana tectoria described by Corti, whose
work appeared at the same time, the nature of this canal has until comparatively
Fig. 520. — DISTRIBUTION
OF THE COCHLEAR
NERVES IN THE LAMINA
SPIRALIS (after Henle).
A, part of the modiolus
and spiral lamina showing
the cochlear nerves form-
ing a network, viewed from
the base ; 1, the twigs of
the nerve issuing frem the
tractus spiralis foramino-
sus ; 2, the branches of
the nerve entering by the
central canal of the modi-
olus ; 3, wide plexus in
the bony lamina spiralis ;
4, close plexus at its
border ; 1 1, labium tym-
pauicum; zi, zona interna ;
z e, zona externa ; 1 8 p,
ligamentum spirale. 13,
part of the nerves ex-
tracted and more highly
magnified ; 2, twigs of the
nerve from the modiolus
close to the lamina spiralis
ossea ; y s, spiral gangli-
form enlargement of the
nerve (habenaria gan-
glionaris) ; f s, nerve-fibres
running spirally along the gangliforra swelling (Henle) ; 3, wide plexus ; 4, close plexus
of nerve -fibres as in A.
MIXUTE STRUCTURE OF THE COCHLEA. 763
recently been generally misconceived. The history of the discovery and subsequent
appreciation of the nature of the canalis membranacea is fully given by Reichert.
(Abhandl. d. Konigl. Akad. d. Wissensch., Berlin, 1864.)
Cochlear division of the auditory nerve. — The nerve of the cochlea is
shorter, flatter, and broader than any of the other nerves of the internal
ear, and perforates the bone by a number of foramina at the bottom of
the internal rneatus, below the opening of the Fallopian aqueduct. These
foramina are arranged in a shallow spiral groove (tractus spiralis fora-
minulentus) in the centre of the base of the cochlea ; and they lead into
small bony canals, which follow first the direction of the axis of the cochlea,
through the modiolus, and then radiate outwards, between the plates of
the bony lamina spiralis. In the centre of the spiral groove is a larger
foramen which leads to the canalis centralis modiolL Through the central
foramen and straight canal the filaments for the last half-turn of the
lamina spiralis are conducted ; whilst the first two turns are supplied by
filaments which occupy the smaller foramina and bent canals. In the
bone the nerves have dark outlines, and near the edge of the spiral lamina
they form a plexus which contains ganglion-cells, and may be considered as
a spiral ganglion contained in an osseous canal, canalis spiralis modioli,
already mentioned. From the outer side of this ganglion the fibres, still
possessing the dark outline, pass onwards with a plexiform arrangement, and,
emerging from the bone beneath the labium tympanicum of the limbus,
are collected into bundles, which, opposite a line of perforations situated at
the junction with the membrana basilaris and named habenula perforata,
present the appearance of conical extremities entering those perforations.
Beyond this they have not yet been traced with certainty, although it seems
probable, as suggested by Kolliker, that the nerves are in continuity with
spindle-shaped cells in the organ of Corti.
Microscopic structure. — The limlus lamina spiralis is a thick structure
continuous with the periosteum of the vestibular surface of the osseous
lamina. Its free surface is thrown into a number of fungiform elevations
narrower at the base than at their extremities. Towards the inner part
of the limbus these elevations are short and vertical, but those which are
placed further out are more and more oblique and longer, and the labium
vestibulare is formed by the outermost of them, which are lengthened into
rib-like processes with flat extremities placed edge to edge, overhanging
the sulcus spiralis like teeth. In the spaces between the elevations numer-
ous small bodies like nuclei are disposed. In the floor of the sulcus
spiralis where the labium tympanicum is continued into the membrana
basilaris a series of elevations (apparent teeth of Corti) are directed into
the membrane, and between their outer extremities are the oblique perfora-
tions occupied by the conical extremities of the nerve-bundlea. This part
is the habenula perforata of Kolliker : it is described by him along with the
membrana basilaris, and by Henle along with the limbus. Henle considers
the appearance of elevations as caused merely by the nerve-bundles grooving
the under surface and leaving thicker structure between.
The membrana basilaris is divisible into an inner and an outer zone.
The inner zone (habenula tecta vel arcuata) is covered over by the rods of
Corti ; the outer zone (zona pectinata) is attached peripherally to the walls
of the canal through the medium of the cochlear ligament. The inner
zone, together with the apparatus on its surface, continues, according to
Henle, of an uniform breadth of about -aj-oth of an inch, both in the dif-
ferent parts of the same cochlea, and likewise in different animals : so that
764 THE EAR.
Fig. 521.
Fig. 521. —UPPER OR YESTIBULAR SURFACE OF A NARROW STRIP OF THE LAMINA
SPIRALIS MEMBRANACEA (from Kolliker after Corti). 2-p
The drawing is defective as regards the organ of Corti, but explains the nomenclature
of the parts introduced by that author, and more or less adhered to by subsequent writers,
although variously departed from in some of its details. The nomenclature adopted in the
text has been selected from various writers, and it will be observed difiers considerably
from the following : a, periosteum of the zona spiralis ossea ; d w, lamina spiralis mem-
branacea ; d w', zona denticulata ; d f, habenula sulcata ; d, place where the perios-
teum thickens ; e, granules in the areolse of the habenula sulcata ; fg, teeth of the first
series; fffh, sulcus vel semicanalis spiralis; A, its lower wall ; h w, habenula denticu-
lata; Jim, apparent teeth ; nt, teeth of the second series ; np, inner segments of the
same; o, swellings with nuclei ; pq and qz, articulating pieces of the same : f, anterior
segments of the second series ; s s s, three cylindrical cells placed on them ; w, epithelial
cells placed under the membrane of Corti ; w' w, zona pectinata ; a a, band-like
elevations of the habenula sulcata ; #, placed where a tooth of the first series takes
its origin ; 7, holes between the apparent teeth ; 5, fore part of one of the teeth of the
second series thrown back ; e, one of them in its place without its epithelial cells ; £ one
with only the lowest epithelial cell ; i\, one with the two lowest cells ; 8, striae or slight
elevations of the zona pectinata ; /c, periosteum attaching the lamina spiralis, with A,
apertures between the bundles.
the increasing breadth of the membrane from base to apex of the cochlea
is due to broadening of the zona pectinata. According to the same
observer the membrane is mainly homogeneous, and in the outer zone is
thicker than in the inner, and somewhat tuberculated ; but on the surface
towards the membranous canal it is transversely striated by a layer of
extremely delicate fibres ; and on the other surface is a less perfect layer
of fibres with spindle-shaped corpuscles, which are placed longitudinally,
and in young subjects are arranged so as to cover the inner zone and the
attachment to the spiral ligament, leaving the outer zone free. A single
layer of epithelium lies on the surface.
The ligamentum spirale (musculus cochlearis of Todd and Bowman) is
triangular in section, receiving at its inner angle the basilar membrane, and
spreading out rapidly to be attached by a broad base to the wall of the
cochlea. Its fibres are directed outwards from the membrane to the bone,
and it exhibits nuclei, like the ciliary muscle, whence Todd and Bowman
conceived it to be muscular. Hensen represents it as composed of branch-
ing nucleated cells.
The organ of Corti. — Under this name may be comprised the whole of
the structures intervening between the membrana basilaris and meinbrana
tectoria. The most prominent part of it is formed by an outer and an inner
series of rods, which, attached respectively to the inner and outer margins of
the inner zone of the basilar membrane, meet together like the beams of a
roof, and cover in a three-sided space, of which the inner zone of the basilar
membrane is the floor. These structures, the fibres or rods of Corti, are
closely adherent by their lower extremities to the basilar membrane. They
are placed with the regularity of piano keys, and have been likened in con-
THE ORGAN OF CORTI.
Fig. 522.
765
Fig. 522. — DIAGRAMMATIC OUTLINE OP A RADIAL SECTION THROUGH THE LAMINA SPIRALIS
MEMBRANACEA, ORGAN OF CORTI, &c. (after Kolliker, Heule, and other*). --^
This figure may be regarded as a more enlarged and explanatory view of the part of
fig. 518 representing the organ of Corti : S V, part of the scala vestibuli ; C C, canalis
cochleae ; S T, scala tympani ; R, membrane of Reissner, forming the partition between
the scala vestibuli and the canalis cochleae ; I s o, a small part of the lamina spiralis ossea
cut in the direction of one of the canals transmitting the cochlear nerves, nc; p, perios-
teum lining the scala tympani ; Us, limbus laminae spiralis, presenting a great thickening
of the periosteum, in which over the extremity of the osseous spiral lamina is found the
sulcus spiralis s s, and upon the upper surface of which are the toothed projections ; I v,
labium vestibulare ; 1 1, labium tympanicum of the sulcus spiralis ; Ivtolsp, the lamina
spiralis meinbranacea with its contained parts ; mt, membrana tectoria passing from the
limbus laminae spiralis to the outer wall of the cochlear tube ; mb, membrana basilaris,
stretched from the labium tympanicum to the outer wall of the cochlear tube, where it
expands in the ligamentum spirale, I sp ; the part marked by the letters m b, between two
short dotted lines, forms the zona tecta or z. arcuata ; the part indicated by m b' and between
the adjacent dotted lines is the zona pectinata ; C, the organ of Corti ; i, the internal rods ;
e, the external rods ; these are set by their lower flattened ends on the basilar membrane,
and are articulated together at their upper parts, a, the inner overlapping the outer ; a
nucleus is seen close to the base of each of the rods close on the basilar membrane ; m r,
membrana reticularis, stretched to the outer wall of the cochlea, pc; below mr, the cells
of Corti lying obliquely on the outer rods, and between them the cells of Deiters, and
between these and the outer wall of the cochlea epithelial cells ; between a and mr, are
indicated the perforations through which the hair-like terminations of the cells of Corti
project : the sulcus spiralis is seen filled with cylindrical and other epithelium.
sistency to cartilage. The inner rods are more closely set and more nume-
rous than the outer, and appear generally to be of a uniform breadth,
flattened, and with a nucleiform body placed subjacent to the lower
extremity. The outer rods are narrow and cylindrical in their shafts, and
expanded at the lower extremity, which has a nucleiform body subjacent to
it, as in the case of the inner rods. At their upper ends where they meet
together, both sets of rods are thickened, and the parts which are in con-
tact (coins articulaires externes et internes of Corti) have the appearance of
quadrilateral plates directed outwards so that those of tUe inner row lie
over those of the outer row, and those of the outer row are bent backwards
from the direction in which the rods to which they belong are placed.
From the junction line of the rods there extends outwards an extremely
delicate network, the lamina reticularis of Kolliker (i. velamentosa, Deiters),
which, it may be gathered from different accounts, is mainly constructed of
a layer of squamous cells so disposed as to leave at least three rows of
large perforations between them, and which are cemented together by a net-
work of intervening substance which is sometimes detected when the cells are
not. At its inner margin this lamina is united by flat plates to the inner
766
THE EAE.
series of rods, and by narrow bodies with flattened extremities to the outer
series : at its outer margin it has not yet been demonstrated that it is
attached to the wall of the cochlea, although it has been supposed that its
function might be to give fixity to the rods of Corti. Besides the rods and
the lamina reticularis the organ of Corti presents various cellular elements.
Of these the most important are an outer and inner series of cells with stiff
Fig. 523.
A.
Fig. 523 A. — VIEW FROM ABOVE OP THE ORGAN OP CORTI AND LAMINA RETICULARIS IN
THE Ox (from Kolliker). ^
a, inner rods or fibres of Corti ; 6, inner ends of the same with the deeper attached
nuclei ; c, articulating part of the same ; d, clear plates appended, which with others
from the outer rods form the commencement of the membrana reticularis ; e, outer rods
or fibres of Covti ; /, their articulating portions ; g, their terminations at the membrana
basilaris ; h, plates of the outer rods belonging to the membrana reticularis ; i i,
apparent extension of the ends of the fibres of Corti in the stride of the zona pectinata of
the basilar membrane ; I, their inner connecting plates ; I', their outer connecting plates ;
m, %, o, first, second, and third series of perforations ; p, rectangular terminal part of
the lamina ; q, prolongation of this in the form of fibres upon the large epithelial cells of
the organ of Corti.
Fig. 523 B.— THE ORGAN OP CORTI OF THE CAT (from Kolliker). 5-f
1, the organ of Corti from above ; c, the articulated part of the inner fibres or rods ;
d, connected plates which form the commencement of the membrana reticularis ; f,
articulating portions of the outer rods ; /', one of these connected with a filamentous
process, and presenting granular or punctated contents ; ra, n, o, first, second, and third
row of perforations, in which the cilia of Corti's cells are represented as dark arched lines ;
a, inner ciliated cells with ($) their cilia, forming the outermost part of the thick
epithelium of the sulcus spiralis (7), and which covers the inner fibres (rods) of Corti as
far as their articulating pails ; 5, outer part of the network of the lamina reticularis ;
2, a cell of Corti with its hairs, but no visible filamentous appendage ; 3, lateral view of
the lamina reticularis with the bundles of cilia of the cells of Corti.
BLOOD-VESSELS OF THE LABYKIXTH. 767
cilia projecting from their upper extremities. The inner ciliated cells form
a single row resting on the articulating ends of the inner rods : the outer
ciliated cells (pedunculated cells of Corti) are placed in three rows external
to the outer rods, aud are described as attached by pointed extremities to
the membrana basilaris, and with their ciliated ends opposite the three rows
of openings in the lamina reticularis ; so that sometimes when the lamina
is detached the ends of the cells are detached with it. Alternating with
the outer ciliated cells are the cells of Deiters, which are fusiform and
prolonged into a thread at each extremity, one passing up to the
lamina reticularis, and the other down to the outer zone of the membrana
hasilaris. The upper surface of the remaining part of the basilar membrane
is covered with hexagonal epithelium-cells. The sulcus spiralis is likewise
filled with large epithelial cells, which, according to Kolliker, project in a
swelling distinct from the proper organ of Corti.
The mode of termination of the nerves, as has been already said, is uncer-
tain, but minute fibres, consisting of axis-cylinders only, have been traced
by Deiters into the organ of Corti, and his statements receive some support
from Kolliker and Henle. These fibres are said to divide into a radiating set
distributed both above and beneath the rods, and into a spiral set which are
continued in the longitudinal direction of the canal.
The membrana tectoria is described by Henle as presenting three zones.
The inner of these is delicate and presents large openings corresponding to
elevations of the limbus ; the middle or generally recognised part is formed
of layers of fibres directed outwards, but yet crossing each other ; and the
outer part, unrecognised by most observers, is extremely delicate, forming a
network, the openings in which are elongated in the direction of the canal.
The membrane of Heissner is an extremely easily torn membrane, on both
sides of which epithelium has been described.
On the microscopic anatomy of the cochlea may be consulted Henle's Systematische
Anatomic ; Kolliker's Gewebelehre, 4th edition ; also the papers of Corti, Claudius,
Deiters, and Hensen, in Vols., III. VII., X., and XIII. of Siebold and Kolliker's
Zeitsch. f. Wissensch. Zoologie; and Deiters Untersuchungen liber die Lamina Spiralis
Membranacea.
BLOOD-VESSELS OF THE LABYRINTH.
Arteries. — The internal auditory artery, a branch from the basilar, enters
the internal meatus of the ear with the auditory and facial nerves, and
at the bottom of that shallow canal divides into vestibular and cochlear
branches.
The vestibular branches are distributed to the common sinus, sacculus,
and semicircular canals, with the branches of nerve which they accompany
through the bony foramina. At first they ramify on the exterior of the
membranous labyrinth, and end in capillaries both on the outer surface and
in the substance of the special glassy layer. The plexus is best marked
internally near the ending of the nerves.
The cochlear branches, twelve or fourteen in number, traverse the many
small canals in the modiolus and bony lamina spiralis, and form in the
latter a capillary plexus that joins at intervals the vas spirale, to be pre-
sently described. From this plexus offsets are distributed in the form of a
fine network on the periosteum, but the vessels do not anastomose across
the membrana basilaris. The vas spirale is a single, sometimes branched
vessel which runs along the under surface of the membranous zone, near
the bone : it is like a capillary in texture,, but larger in size, and is pro-
768 THE EAR.
bably venous. On the outer wall of the membranous canal there is a
specially vascular strip which has received the name of stria vascularis.
Besides the foregoing vessel, which is the chief artery of the internal ear,
the stylo-mast oid branch of the posterior auricular, and occasionally the occi-
pital artery (Jones), send twigs to the vestibule and the posterior semicircular
canal.
Veins. — The veins of the cochlea issue from the grooves of the cochlear
axis and join the veins of the vestibule and semicircular canals : these accom-
pany the arterial branches, and, uniting with those of the cochlea at the base
of the modiolus, pour their contents into the superior petrosal sinus.
DEVELOPMENT OF THE EAR.
In the very young embryo the first rudiment of the ear is seen in the form of a
small vesicle — the primary auditory vesicle lying at the side of the third primary
cerebral vesicle. It has to a certain extent an appearance similar to that of the
primary optic vesicle situated further forwards, and was long very naturally supposed
to be formed like it by a protrusion of the wall of the primary medullary cavity of
the brain ; but it has latterly been established by various observers that it is pro-
duced solely by invagination of the integument, and has no original connection
with the brain. During the third day of incubation it can be seen in the chick, still
open to the outside, above and behind the second branchial lappet. It soon becomes
completely closed, and is afterwards developed into the membranous labyrinth.
The first complication which the vesicle exhibits is by the extension of a process
upwards and backwards, which remains permanent in the lower vertebrata, but in
mammals is obliterated, its vestiges remaining in the aqueduct of the vestibule. The
semicircular canals next appear as elongated elevations of the surface of the primary
vesicle : the middle portion of each elevation becomes separated from the rest of the
Fig. 524.— OUTLINES SHOWING THE FORMATION OP THE EXTERNAL EAR IN THE FCETUS.
A, head and upper part of the body of a human foetus of about four weeks (from
nature). ^ Four branchial plates (the first, forming the lower jaw, is marked 1), and
four clefts are shown ; the auditory vesicle (a), though closed, is visible from the tran-
sparency of the parts, and is placed behind the second branchial plate.
B, the same parts in a human foetus of about six weeks (from Kcker). f The third
and fourth plates have nearly disappeared, and the third and fourth clefts are closed ;
the second is nearly closed ; but the first (!') is somewhat widened posteriorly in con-
nection with the formation of the mealus externus.
C, human foetus of about nine weeks (from nature), f The first branchial cleft is
more dilated, and has altered its form along with the integument behind it in connection
with the formation of the meatus externus and the auricle.
DEVELOPMENT OF THE EAR.
769
vesicle by bending in of its walls under it, and thus the elevation is converted into
a tube open at each end, which subsequently becomes elongated and presents an
ampullar dilatation. The cartilage which forms the osseous labyrinth is continuous
with that of the rest of the primordial cranium. The cartilaginous walls of the
cavity are united by connective tissue to the vesicle : this connective tissue, according
to Kolliker, becomes divided into three layers, of which the outer forms the lining
periosteum, the inner forms the external walls of the membranous labyrinth, while
the intervening layer swells up into gelatinous tissue, the meshes of which become
wider and wider, till at last the space is left which ultimately is found containing
perilymph.
Fig. 525.
Fig. 525. — LABYRINTH OF THE HUMAN FCETUS OP FOUR
WEEKS, MAGNIFIED (from Kolliker).
A, from behind ; B, from before; v, the vestibule ;
r v, recessus vestibuli, giving rise later to the aqueduct ;
c s, commencement of the semicircular canals ; a,
upper dilatation, belonging perhaps to another semi-
circular canal ; c, cochlea.
The cochlea appears at first as a prolongation
downwards from the auditory vesicle, but afterwards
become tilted forwards. This prolongation of the
auditory vesicle is the rudimentary canalis mem-
branacea. Close to it is placed the cochlear nerve,
with a gangliform extremity. The canal becomes elongated in a spiral direction, and
the ganglion, which is elongated with it, becomes the ganglion spirale. Between the
canal and the cartilaginous wall which afterwards surrounds it a large amount of con-
nective tissue intervenes, and in this the cavities of the scala vestibuli and scala tym-
pani appear at a later period, precisely as does the space for the perilymph in the
Fig. 526.
Fig. 526. — TRANSVERSE SECTION OF
THE COCHLEA IN A FCETAL CALF,
MAGNIFIED (from Kolliker).
C, the wall of the cochlea, still carti-
laginous ; c c, canalis cochleae ; I s,
placed in the tissue occupying the
place of the scala vestibuli indicates
the lamina spiralis ; n, the central
cochlear nerve ; g, the place of the
spiral ganglion ; S, the body of the
sphenoid ; c k, chorda dorsalis.
vestibule. The modiolus and spiral
lamina, according to Kolliker, are
ossified without intervention of car-
tilage. Within the canalis mem-
branacea Kolliker finds in the em-
bryo a continuous epithelial lining,
thin on the membrane of Reissner and on the outer wall, but forming a thick eleva-
tion in the position of the rods of Corti, and a larger elevation more internally, filling
up the sulcus spiralis. On the surface of this latter elevation he observes a transpa-
rent body, the membrane of Corti.
With regard to the middle and external ear, it has been already explained at pages
65 and 66 that the external aperture, the tympanic cavity, and the Eustachian tube,
are formed in the posterior or upper part of the first branchial cleft, which remains
open except at the place where the passage is interrupted by the formation of the
membrana tympani ; and also that the incus and malleus are formed in the first
branchial lappet from the proximal part of Meckel's cartilage, and the stapes and
stapedius muscle and the styloid process in the second lappet. It is pointed out by
3 E
770
THE EAR.
Kolliker that during the whole period of foetal life the tympanic cavity is occupied
by connective tissue, in which the ossicles are imbedded ; and that only after the
breathing process is commenced this tissue recedes before an expansion of the mucous
membrane. The pinna is gradually developed on the posterior margin of the first
branchial cleft. It is deserving of notice that congenital malformation of the external
ear, with occlusion of the meatus and greater or less imperfection of the tympanic
Fig. 527.
Fig. 527. — VIEWS OF THE
CARTILAGE OP MECKEL
AND PARTS CONNECTED
WITH THE FIRST AND
SECOND BRANCHIAL
PLATES.
A (after Kolliker), head
of a foetus of about eigh-
teen weeks, showing the
cartilage of Meckel in con-
nection with the malleus,
&c. M, the cartilage of
Meckel of the right side.
B (from nature). An
enlarged sketch explana-
tory of the above view; z,
the zygomatic arch ; ma,
the mastoid process ; mi,
portions of the lower jaw
of which the parts near
the angle and the sym-
physis have been removed ;
M, the cartilage of Meckel
of the right side; M', a
small part of that of the
leftside, joiningthe left car-
tilage at s, the symphysis ;
T, the tympanic ring ; m,
the malleus ; i, the incus;
s, the stapes ; sta, the
stapedius muscle ; st, the
styloid process ; p, h, g, the
stylo -pharyngeus, stylo-
hyoid and stylo -glossus
muscles, st-l, stylo-hyoid
ligament attached to the
lesser cornu of the hyoid
bone ; hy, the hyoid bone ;
tk, thyroid cartilage. In
A, the head being turned
somewhat upwards, the
same parts are shown, to-
gether with the surround-
ing muscles, the carotid
artery, jugular vein, &c.
apparatus, are observed in connection with abnormal development of the deeper
parts of the first and second branchial lappets and the intermediate cleft ; while cases
have been observed of the persistence in the neck of the adult of one or more of the
branchial clefts situated behind the first. (Allen Thomson, Proceed. Roy. Soc. of
Edin. 1844, and Edin. Journ. of Med. Sc. 1847.)
THE XOSE. CARTILAGES.
771
THE NOSE.
The nose is the special organ of the sense of smell. It has also other
functions to fulfil ; — for, communicating freely with the cavities of the
mouth and lungs, it is concerned in respiration, voice, and taste ; and by
means of muscles on its exterior, which are closely connected with the
muscles of the face, it assists in the expression of the different passions and
feelings of the mind.
Fig. 528. — LATERAL VIEW OF THE CARTILAGES OP Fig. 528.
THE NOSE (from Arnold), f
a, rigbt nasal bone ; b, nasal process of the
superior maxillary bone ; 1, upper lateral cartilage
or wing-like expansion of the septal cartilage ; 2,
lower lateral cartilage (outer part) ; 2*, inner part
of the same ; 3, sesamoid cartilages.
This organ consists of, first, the anterior
prominent part, composed of bone and car-
tilages, with muscles already described,
which slightly move the cartilages, and two
orifices, anterior nares, opening downwards ;
and, secondly, of the two nasal fossae, in
which the olfactory nerves are expanded.
The nasal fossae are separated from each
other by a partition, septum nasi, formed
of bone and cartilage : they communicate
at the outer side with hollows in the neigh-
bouring bones (ethmoid, sphenoid, frontal,
and superior maxillary); and they open
backwards into the pharynx through the
posterior nares. The skin of the nose is studded, particularly in the grooves
of the alse or outer walls of the nostrils, with numerous small openings,
which lead to sebaceous follicles. Within the margin of the nostrils there
is a number of short, stiff, and slightly curved hairs — mbrissce, which grow
from the inner surface of the alse and septum nasi, as far as the place where
the skin is continuous with the mucous membrane lining the cavity of the
nose.
CARTILAGES OF THE NOSE.
These are the chief support of the outer part of the organ. They occupy
the triangular opening seen in front of the nasal cavity in the dried skull,
and assist in forming the septum between the nasal fossoe. There are usually
reckoned two larger and three smaller cartilages on each side, and one
central piece or cartilage of the septum.
The upper lateral cartilages (cartilagines laterales nasi) are situated in the
upper part of the projecting portion of the nose, immediately below the free
margin of the nasal bones. Each cartilage is flattened and triangular in
shape, and presents one surface outwards, and the other inwards towards
3 E 2
772
THE NOSE.
Fig. 529.
Fig. 530.
the nasal cavity. The anterior margin, thicker than the posterior one,
meets the lateral cartilage of the opposite side above, but is closely united
with the edge of the cartilage of the septum below ; so closely indeed, that
by some, as Henle, the upper lateral are regarded as reflected wings of
the median cartilage. The inferior margin is connected by fibrous mem-
brane with the lower lateral cartilage ; and the posterior edge is inserted into
the ascending process of the
upper maxilla and the free
margin of the nasal bone.
Fig. 529. — FROKT VIEW OF THE
CARTILAGES OF THE NOSE (from
Arnold), f
a, a', nasal bones ; 1, 1', upper
lateral cartilages or wing-like ex-
pansions of the septal cartilage ;
2, 2', lower lateral cartilages.
Fig. 530. — VIEW OF THE CARTI-
LAGES OF THE NOSE FROM BE-
LOW (from Arnold), f
2, 2', outer part of the lower
lateral cartilages ; 2*, 2*, inner
part of the same ; 4, lower edge
of the cartilage of the septum.
The lower lateral cartilages (cartilagines alarum nasi) are thinner than the
preceding, below which they are placed, and are chiefly characterised by their
peculiar curved form. Each cartilage consists of an elongated plate, so bent
upon itself as to pass in front and on each side of the nostril to which it
belongs, and by this arrangement serves to keep it open. The outer
portion is somewhat oval and flattened, or irregularly convex externally.
Behind, it is attached to the margin of the ascending process of the upper
maxilla, by tough fibrous membrane, in which are two or three cartilaginous
nodules (cartilag. minores vel sesamoidese) ; above, it is fixed, also by fibrous
membrane, to the upper lateral cartilage, and to the lower and fore part
of the cartilage of the septum. Towards the middle line it is curved back-
wards, bounding a deep mesial groove, at the bottom of which it meets with
its fellow of the opposite side, and continues to pass backwards, forming
a small part of the columna nasi, below the level of the cartilage of the
septum. This inner part of the cartilage of the ala is thick and narrow,
curls outwards, and ends in a free rounded margin which projects out-
wards towards the nostril. The lower and most prominent portion of the
ala of the nose, like the lobule of the ear, is formed of thickened skin with
subjacent tissue, and is unsupported by cartilage.
The cartilage of the septum has a somewhat triangular outline, and is
thicker at the edges than near the centre. It is placed nearly vertically
in the middle line of the nose, and completes, at the fore part, the separation
between the nasal fossae. The anterior margin of the cartilage, thickest
above, is firmly attached to the back of the nasal bones near their line of
junction; and below this it lies successively between the upper and the
lower lateral cartilages, united firmly with the former and loosely with the
latter. The posterior margin is fixed to the lower and fore part of the
central plate of the ethmoid bone ; and the lower margin is received into
NASAL FOSSAE.
773
the groove of the vomer, as well as into the median ridge between the
superior maxillae.
Fig. 531. — OSSEOUS AND CARTILAGI-
NOUS SEPTUM OP THE NOSE, SEEN
FROM THE LEFT SIDE (from Ar-
nold). §
«, right nasal bone ; 5, superior
maxillary bone ; c, sphenoidal sinus ;
d, perpendicular plate of the ethmoid
bone; e, vomer; 2*, inner part of the
right lower lateral cartilage ; 4, carti-
lage of the septum.
This cartilage is the persistent
anterior extremity of the primor-
dial cranium. In young subjects
it is prolonged back to the body
of the presphenoid bone; and in
many adults an irregular thin
baud remains between the vomer
and the central plate of the
ethmoid.
Fig. 531.
NASAL FOSSAE.
The nasal fossae, and the various openings into them, with the posterior
nares, have been previously described as they exist in the skeleton, and the
Fig. 532.
Fig. 532. — TRANSVERSE VERTICAL SECTION OF TUB NASAL FOSS.E SEEN FROM BEHIND
(from Arnold). ^
1, part of the frontal bone ; 2, crista galli ; 3, perpendicular plate of the ethmoid ; be-
tween 4 and 4, the ethmoid cells ; 5, right middle spongy bone ; 6, left lower spongy bone;
7, vomer ; 8, malar bone ; 9, maxillary sinus ; 10, its opening into the middle meatus.
greater part of that description is also applicable generally to the nose in a
recent state ; but it is proper to mention certain differences in the form and
774 THE NOSE.
dimension of parts, which depend on the arrangement of the lining mem-
brane, viz. —
Throughout the whole of the nasal fossae it is to be observed that —
First, owing to the thickness of the membrane in question, (which not only lines
the walls of the fossae, but covers the spongy bones on both sides,) the nasal cavity is
much narrower in the recent state. Second, in consequence of the prolongations of
membrane on their free margins, the turbinate bones, and more particularly the
lower pair, appear in the recent state to be both more prominent, and longer in the
direction from before backwards, than in the dried skull. Third, by the arrange-
ment of the mucous membrane round and over the orifices which open into the
nasal fossae, some of the foramina in the bones are narrowed, and others completely
closed.
In the individual parts of the nasal fossae the following particulars are to be
noticed.
In the upper meatus, the small orifice which leads into the posterior ethmoidal
cells is lined by a prolongation of the thin mucous membrane which continues into
those cavities ; but the spheno-palatine foramen is covered over by the Schneiderian
membrane, so that no such opening exists in the recent nasal fossa.
In the middle meatus the aperture of the infundibulum is nearly hidden by an
overhanging fold of membrane ; it leads directly into the anterior ethmoidal cells,
and through them into the frontal sinus. Below and behind this, the passage into
the antrum of Highmore is surrounded by a circular fold of the pituitary membrane,
(sometimes prominent and even slightly valvular,) which leaves a circular aperture
much smaller than the foramen in the bony meatus.
In the lower meatus, the inferior orifice of the nasal duct is defended by one or
two folds of membrane; and when there are two, the folds are often adapted so
accurately together as to prevent even air from passing back from the cavity of the
nose to the lachrymal sac.
In the roof the apertures in the cribriform plate of the ethmoid bone are closed
by the membrane, but the openings into the sphenoidal sinuses receive a prolonga-
tion from it.
In the Jloor the incisor foramen is in the recent state generally closed. Some-
times, however, a narrow funnel-shaped tube of the mucous membrane descends
for a short distance into the canal, but is closed before it reaches the roof of the
palate. Vesalius, Stenson, and Santorini, believed that this tube of membrane
opened generally into the roof of the mouth by a small aperture close behind the
interval between the central incisor teeth. Haller, Scarpa, and, more recently, Jacob-
son, find that in man it is usually closed, and often difficult of detection. (See
Cuvier's Report on a paper by Jacobson, " Annales du Museum d'Hist. Naturelle ; "
Paris, 1811 ; vol. xviii. p. 412.)
MUCOUS MEMBRANE.
The pituitary or Schneiderian membrane, which lines the cavities of the
nose, is a highly vascular mucous membrane, inseparably united, like that
investing the cavity of the tympanum, with the periosteum and peri-
chondrium over which it lies. It is continuous with the skin through
the nostrils ; with the mucous membrane of the pharynx through the pos-
terior apertures of the nasal fossae ; with the conjunctiva through the nasal
duct and lachrymal canaliculi ; and with the lining membrane of the several
sinuses which communicate with the nasal fossae. The pituitary membrane,
however, varies much in thickness, vascularity, and general appearance in
these different parts. It is thickest and most vascular over the turbiuato
bones (particularly the inferior), from the most dependent parts of which it
forms projections in front and behind, thereby increasing the surface to some
extent. On the septum nasi the pituitary membrane is still very thick and
spongy ; but in the intervals between the turbinate bones, and over the
floor of the nasal fossae, it is considerably thinner. In the maxillary, frontal,
MUCOUS MEMBEAKB OF THE XOSE.
775
and sahenoidal sinuses, and in the ethmoidal cells, the mucous lining mem-
brane, being very thin and pale, contrasts strongly with that which occupies
the nasal fossae.
Fig. 533. — OUTER WALL OF THE LEFT NASAL FOSSA, COVERED BY TUB PITUITARY
MEMBRANE (from Arnold), f
1, frontal bone ; 2, left nasal bone ; 3, superior maxillary ; 4, body of the sphenoid with
the sphenoidal sinus ; 5, projection of the membrane covering the upper spongy bone ; 6,
that of the middle ; 7, that of the lower ; the upper, middle, and lower meatuses are seen
below the corresponding spongy bones; 8, opening of the Eustachian tube ; 9, depression
of the lining membrane of the nose in the anterior palatine canal.
In respect of the characters of the mucous membrane, three regions of
the nasal fossae may be distinguished. Thus, the region of the nostrils,
including all the part which is roofed by the nasal cartilages, is lined with
stratified squamous epithelium ; the remainder of the fossae is divisible
into two parts, viz. , the olfactory region in which the epithelium is non-ci-
Fig. 534.
Fig. 534. — VERTICAL SECTION OF A SMALL PORTION op
THE MEMBRANE OF THE NOSE FROM THE OLFACTORY
HKGION (from Ecker), ^
a, coloured part of the epithelium ; a', nuclei ; 5,
deeper part containing the olfactory cells and fila-
ments ; c, connective tissue of the mucous membrane ;
d, one of the mucous glands : d', its duct; e, twig of
the olfactory nerve ; c', small twig passing to the
surface.
liated and columnar, and the respiratory
region in which it is ciliated and columnar.
The membrane in the respiratory part, con-
sisting of the inferior turbinated and all the
lower portions of the fossae, is studded with nu-
merous mucous glands, which are of branched acinated appearance, and open
by apparent orifices on the surface. These are most numerous about the
middle and hinder parts of the nasal fossae, and are largest at the back of
the septum near the floor of the nasal cavity. They are much smaller and
776
THE NOSE.
leps numerous in the meuVbraue lining the several cavities which communi-
cate with the nasal fossse.
The olfactory region or that in which the olfactory nerve is distributed,
includes the upper and middle turbinated parts, and the upper portion
of the septum. Its mucous membrane is thicker and more delicate in
consistence than that of the ciliated region, being soft and pulpy. The
columnar cells on its surface are prolonged at their deep extremities into
threads, which have been observed to communicate with stellate cells of
ihe connective tissue. Beneath the columnar cells is a considerable thick-
ness of densely nucleated tissue, compared by Henle to the cortical brain-
substance. The glands of this region are numerous ; but are of a more
simple structure than those in the lower part of the fossae.
Fig. 535. — CELLS AND TERMINAL NERVE-FIBRES
OP THE OLFACTORY REGION (from Frey after
Schultze).
1, from the frog ; 2, from man ; a, epithelial
cell, extending deeply into a ramified process;
b, olfactory cells ; c, their peripheral rods ;
e, their extremities, seen in 1 to be prolonged
into ciliary hairs ; d, their central filaments ; 3,
olfactory nerve-fibres from the dog ; a, the
division into fine fibrillse.
Olfactory Cells. — Intermixed with the
columnar epithelial cells of the olfactory
region, and so numerous as to surround
each of them, are certain peculiar bodies,
each consisting of a spindle - shaped
nucleated cell, from which proceed a
superficial and a deep process. The
superficial process is a cylindrical or
slightly tapering thread passing directly
/7 ^BIKflflMi^! 'mt'm *° ^ne sur^ace) and terminating abruptly
f IfMO at the same level as the epithelial cells
I '*Wwf^ ^t between which it lies : the deep process
A I3P1 *s more slender and passes vertically
invrards. Both processes frequently pre-
sent a beaded appearance similar to that
observed in fine nerve - filaments, and
considered to be of a similar accidental origin. It was suggested by Max
Schultze, the discoverer of the olfactory cells, and is highly probable, that
the deep processes are directly continuous with the filaments of the olfactory
nerve, but the continuity does not appear to have been actually observed.
The superficial process of the olfactory cell was observed by Schultze to be sur-
mounted by a short stiff hair-like process, and has been so described by others ; but
both the discoverer and others are now agreed that this appearance results from the
coagulation of albumen escaped from the interior of the process. Long and fine hair-
like processes do, however, exist on the olfactory membranes of amphibia, reptiles,
and birds, and had been previously pointed out by Schultze.
Olfactory Nerve. — The filaments of this nerve, lodged at first in grooves
on the surface of the bone, enter obliquely the substance of the Schneiderian
membrane, and pass to their distribution between its mucous and fibrous
layers. The nerves of the septum are rather larger than those of the outer
wall of the nasal fossse ; they extend over the upper third of the septum,
OLFACTORY KERVE.
777
and as they descend become very indistinct. The nerves of the outer wall
are divided into two groups — the posterior branches being distributed over
the surface of the upper spongy bone, and the anterior branches descending
ever the plain surface of the ethmoid and the middle spongy bone.
Fig. 530.
XT I
Fig. 536. — NERVES OF THE SKPTUJI NASI, SEEN FROM THE RIOHT SIDE (from Sappey
after Hirscbfeld and Leveille). f
I, the olfactory bulb ; 1, the olfactory nerves passing through the foramina of the
cribriform plate, and descending to be distributed on the septum ; 2, the internal or
septal twig of the nasal branch of the ophthalmic nerve ; 3, naso-palatine nerves.
The olfactory nerves as they descend ramify and unite in a plexiform
manner, and the filaments join in brush-like and flattened tufts, which,
spreading out laterally and communicating freely with similar offsets on
Fig.' 537.
Fig. 537. — NERVES OF THE OUTER WALLOP
THE NASAL FOSSJE (from Sappey after
Hirschfel.l and Leveille). §
1, network of the branches of the olfac-
tory nerve, descending upon the region of the
superior and middle turbinated bones ; 2,
external twig of the ethmoiclal branch of the
nasal nerve ; 3, spheno-palatine ganglion ;
4, ramification of the anterior palatine
nerves ; 5, posterior, and 6, middle divi-
sions of the palatine nerves ; 7, branch to
the region of the inferior turbinated bone ;
8, branch to the region of the superior and
middle turbinated bones ; 9, naso-palatine
branch to the septum cut short.
each side, form a fine net-work
with elongated and narrow intervals
between the points of junction ; but
it is impossible to trace by dissection
the termination of the nerves in the
membrane, in consequence of the difficulty of recognising the filaments,
destitute of dark outline, as they lie among the other nucleated tissues.
In their nature the olfactory filaments differ much from the fibres of the
cerebral and spinal nerves : they contain no white substance of Schwann,
778
THE NOSE.
are pale, and finely granular in texture, firmly adherent one to anothef,
and have oval corpuscles on their surface.
The greater part of the mucous membrane of the nasal fossse is provided
with nerves of common sensibility, derived from branches of the fifth pair :
these have already been described at pp. 599, 603 and 604.
Blood-vessels. — The arteries and veins of the nose are derived from nume-
rous sources : those of the interior form rich plexuses of capillaries in the
lining membrane. The description of the arteries will be found at pp. 350,
356, 361 and 362 ; that of the veins at pp. 456 and 464.
DEVELOPMENT OP THE NOSE.
The organ of smell, as was first pointed out by V. Baer, owes its origin, like the
primary auditory vesicle and the crystalline lens of the eye, to a depression of the
integument. This depression, the primary olfactory groove, is at first encircled
by a uniform wall, and is unconnected with the mouth. This stage has been
observed by Kolliker in the human embryo of four weeks. Soon, hoAvever, by the
unequal growth of the surrounding parts, a groove is formed, descending from the
pit and passing into the mouth. Thus the middle frontal process is isolated
between the grooves of opposite sides, while the lateral frontal process separates
the nostril from the eye (p. 65). The maxillary lobes, growing forwards from behind
the eyes, complete the boundaries of the nostrils, which then open into the fore part
of the mouth. Kolliker observes this stage in the latter half of the second month.
The palate subsequently grows inwards to the middle line, as has been elsewhere
stated, and separates the nasal from the buccal cavity ; leaving only the extremely
minute communication of the incisor foramen. Meanwhile, with the growth of the
face, the nasal fossae deepen, and the turbinated bones make their appearance as
processes from their walls. Observations are still wanting to determine whether the
olfactory nerves are developed from the bulbs, and have thus a cerebral origin, or are
separately formed from peripheral blastema like all other nerves, with the exception
of the optic.
Fig. 537.*
ABC
Fig. 537.* VIEWS OP THE HEAD OP HUMAN EMBRTOES, ILLUSTRATING: THE DEVELOPMENT
OP THE NOSE.
A, Head of an embryo of three weeks (from Ecker). ]f 1, anterior cerebral vesicle ;
2, middle vesicle ; 3, nasal or middle frontal process ; 4, superior maxillary process ; 5,
eye ; 6, inferior maxillary process or first visceral plate, and below it the first cleft j 7,
8, and 9, second, third, and fourth plates and clefts.
B, Head of an embryo of about five weeks (from Ecker). ^
1, 2, 3, and 5, the same parts as in A ; 4, the external nasal or lateral frontal process,
inside which is the nasal groove ; 6, the superior maxillary process ; 7, the inferior
maxilla ; x , the tongue seen within the mouth ; 8, the first branchial cleft which becomes
the outer part of the meatus auditorius externus.
C, View of the head of an embryo of eight weeks seen from below, the lower jaw having
been removed (from Kolliker). |
?i, the external nasal apertures ; i, intermaxillary or incisor process, and to the outer
side of this the internal nasal aperture ; m, one of the palatal processes of the upper jaw,
which advancing inwards from the sides form the partition between the mouth and nose ;
p, common cavity of the nose, mouth, and pharynx.
OKGANS OF DIGESTIOX. THE MOUTH. 779
SECTION VI.— SPLANCEDTOLOGY.
UNDER the division Splanchnology will be described those organs of the
body which have not found a place in any of the foregoing parts of the
work. These consist of the organs of digestion, the organs of respiration,
the urinary organs, and the organs of generation.
ORGANS OF DIGESTION.
The digestive apparatus includes that portion of the organs of assimilation
within which the food is received and partially converted into chyle, and
from which, after the chyle has been absorbed, the residue or excrement is
expelled. It consists mainly of a tubular part, — the alimentary canal, to-
gether with various glands of which it receives the secretions.
The alimentary canal is a long membranous tube commencing at the
mouth and terminating at the anus, composed of certain tunics or coats, and
lined by a continuous mucous membrane from one end to the other. Its
average length is about thirty feet, being about five or six times the length
of the body. Its upper extremity is placed beneath the base of the skull,
the succeeding portion traverses the thorax, and by far the greater part is
contained within the cavities of the abdomen and pelvis.
The part situated above the diaphragm consists of the organs of mastica-
tion, insalivation, and deglutition, and comprises the mouthy with the teeth
and salivary glands, the pharynx, and the oesophagus or gullet. The
remainder includes that part of the canal which is more immediately en-
gaged in the digestive process, in absorption, and in defecation, as the
stomach and the small and large intestine. The glands which are most
intimately connected with digestion consist of those very numerous smaller
glandular organs which are situated in the mucous membrane of the alimen-
tary canal, and the larger glands, such as the pancreas and liver, whose
ducts open within the canal.
THE MOUTH.
The mouth, or, more definitely, the buccal cavity, is the space included
between the lips and the throat. Bounded by the lips, cheeks, tongue, and
the hard and soft palate, it communicates behind with the pharynx through
an opening called the fauces (isthmus faucium). The cavity of the mouth
is lined throughout by a mucous membrane, which is of a pink rosy hue
during life, but pale grey after death, and which presents peculiarities of
surface and structure to be noticed hereafter.
The lips and cheeks are composed of an external layer of skin, and of a a
internal layer of mucous membrane, together with muscles, vessels, and
nerves already fully described in other parts of this work, some areolar
tissue, fat, and numerous small glands. The free border of the lips is pro-
tected by a dry mucous membrane, which becomes continuous with the
skin, is covered with numerous minute papillae, and is highly sensitive. On
the inner surface of each lip, the mucous membrane forms a fold in the
middle line, connecting the lip with the gums of the corresponding jaw.
These are the frcena or frcenula of the lips : that of the upper lip is much
the larger.
Numerous small glands, called labial glands, are found beneath the
780 ORGANS OF DIGESTION.
mucous membrane of the lips, around the opening of the mouth. They are
situated between the mucous membrane and the orbicularis oris muscle.
They are compound glands of a rounded form, the largest of them not ex-
cseding the size of a split pea ; and they open into the mouth by distinct
orifices.
Between the buccinator muscle and the mucous membrane of the cheek,
by which it is lined in its whole extent, are the buccal glands, similar to the
labial glands, but smaller. Two or three glands, larger than the rest, found
between the masseter and buccinator muscles, and opening by separate ducts
near the last molar tooth, are called the molar glands. The duct of the
parotid gland also opens upon the inner surface of the cheek, opposite to the
second upper molar tooth.
Immediately within the lips and cheek, are the dental arches, consisting
of the teeth, gums, and maxillse. The jaw-bones, the articulation and move-
ments of the lower maxilla, and the muscles used in mastication, are else-
where described. The gums (gingivse) are composed of a dense fibrous
tissue, connected very closely with the periosteum of the alveolar processes,
and covered by a red and highly vascular but not very sensitive mucous
membrane, which is smooth in its general surface, but is beset with fine
papillae in the immediate vicinity of the teeth.
THE TEETH.
In the human subject, as in mammalia generally, two sets of teeth make
their appearance in the course of life, of which the first constitutes the tem-
porary, deciduous, or milk teeth, whilst the second is named the permanent
set. The temporary teeth are twenty in number, ten in each jaw, and the
permanent set consists of thirty two, sixteen above and sixteen below.
Deficiencies in the number of the teeth sometimes occur, and the number is frequently
increased by one or more supernumerary teeth. These are usually small, and pro-
vided with only a single fang ; and, though generally distinct, they are sometimes
attached to other teeth : they occur more frequently near the front than the hinder
teeth, and are more often met with in the upper than in the lower jaw.
General Characters of the Teeth. — Every tooth consists of three portions,
viz., one which projects above the gums and is named the body or crovin, —
another which is lodged in the alveolus or socket, and constitutes the root
or fang, — and a third, intermediate between the other two, and, from being
more or less constricted, named the cervix or neck. The size and form of
each of these parts vary in the different kinds of teeth.
The roots of all the teeth are accurately fitted to the alveoli of the jaws,
in which they are implanted. Each alveolus is lined by the periosteum, which
also invests the contained fang as high as the cervix. This dental perios-
teum, sometimes named the periodontal membrane, is blended with the
dense and slightly sensitive tissue of the gums, which closely surrounds the
neck of the tooth. The roots of all the teeth taper from the cervix to the
point, and this form, together with the accurate adjustment to the alveolus,
has the effect of distributing the pressure during use over the whole socket,
and of preventing its undue action on the apex of the fang through which
the blood-vessels and nerves enter.
The thirty-two permanent teeth consist of four incisors, two canines, four
bicuspids, and six molars in each jaw. The twenty temporary teeth are
four incisors, two canines, and four molars above and below. There are
FORM OF PERMANENT TEETH. INCISORS.
781
no bicuspids among the temporary teeth, but the eight deciduous molars are
succeeded by the eight bicuspids of the permanent set. The relative posi-
tion and arrangement of the different kinds of teeth in the jaws may be
expressed by the following formula, which also exhibits the relation between
the two sets in these respects : —
Temporary teeth
Permanent teeth
( Upper
Lower
MO. CA. IN. CA. MO.
21412 =10
. ^^_____ = 20
21412 =10
MO. BI. CA. IN. CA. BI. MO.
Upper 321412 3 = 16
= 32
(Lower 321412 3 = 16
Special Characters of the Permanent Teeth. — The incisors, eight in number,
are the four front teeth in each jaw, and are so named from being adapted
for cutting or dividing the soft substances used as food. Their crowns are
chisel-shaped, and have a si arp horizontal cutting edge, which by continued
use is bevelled off behind in the upper teeth, but in the lower teeth is worn
down in front, where it comes into contact with the overlapping edges of the
upper teeth. Before being subjected to wear, the horizontal edge of each
incisor tooth is serrated or marked by three small prominent points. The
Fig. 538.
Fig. 538. — INCISOR TEETH OP THE UPPER
AND LOWER JAWS.
«, front view of the upper and lower
middle incisors ; 6, front view of the upper
and lower lateral incisors ; c, lateral view
of the upper and lower middle incisors,
showing the chisel shape of the crown ; a
groove is seen marking slightly the fang
of the lower tooth ; d, the upper and
lower middle incisor teeth before they have
been worn, showing the three pointed pro-
jections of the cutting edge.
anterior surface of the crown is
slightly convex, and the posterior
concave. The fang is long, single,
conical, and compressed at the sides,
where it sometimes though rarely
presents a slight longitudinal furrow.
The lower incisor teeth are placed
vertically in the jaw, but the corre-
sponding upper teeth are directed
obliquely forwards. The upper incisors are, on the whole, larger than the
lower ones.
In the upper jaw the central incisors are larger than the lateral ; the
reverse is the case in the lower jaw, the central incisors being there the
smaller, and being, moreover, the smallest of all the incisor teeth.
The canine teeth (cuspid ati), four in number, are placed one on each
side, above and below, next to the lateral incisors. They are larger and
stronger than the incisor teeth. The crown is thick and conical, convex in
front and hollowed behind, and may be compared to that of a large incisor
782
ORGANS OF DIGESTION.
tooth the angles of which have been removed, so as to leave a single
central point or cusp, whence the name cuspidate applied to these teeth.
this, as
thrown
Fig. 539. Fig. 539. —CANINE TOOTH OP THE UPPER JAW.
a, front view ; &, lateral view, showing the long fang grooved
on the side.
The point always becomes worn down by use. The
fang of the canine teeth is single conical, and com-
pressed at the sides : it is longer than the faDgs of
any of the other teeth, and is so thick as to cause a
corresponding prominence of the alveolar arch : on
the sides it is marked by a groove, an indication, as
it were, of the cleft or division which appears in
the teeth next following.
a The upper canines, popularly called the eye-teeth,
are larger than the lower, and in consequence of
well as of the greater width of the upper range of incisors, they are
a little farther outwards than the lower canine teeth. In the dog-
Fig. 540. Fig. 541. Fig. 540. — FIRST BICUSPID TOOTH OF
THE UPPER AND LOWER, JAWS.
a, front view; 5, lateral view, showing
the lateral groove of the fang, and the
tendency in the upper to division.
Fig. 541. — FIRST MOLAR TOOTH OF THE
UPPER AND LOWER, JAWS.
They are viewed from the outer aspect.
tribe, and in the carnivora gene-
rally, these teeth acquire a great
size, and are fitted for seizing and
killing prey, and for gnawing and
tearing it when used as food.
The bicuspids (bicuspidati), also
called premolars, are four in each
jaw ; they are shorter and smaller
than the canines, next to which
they are placed, two on each side.
The crown is compressed before and behind, its greater diameter being
across the jaw. It is convex, not only on its outer or labial surface, like
the preceding teeth, but on its inner surface also, which rises vertically
from the gum : its free extremity is broader than that of an incisor or canine
tooth, and is surmounted by two pointed tubercles or cusps, of which the
external one is larger and higher than the other. The fang is also flattened,
and is deeply grooved in all cases, showing a tendency to become double.
The apex of the fang is generally bifid, and in the first upper bicuspid the
root is often cleft fora considerable distance; but the bicuspid teeth are very
variable in this respect, and may be, all four, free from any trace of bifidity
of the root. The upper bicuspids are larger than the lower ones, and their
cups are more deeply divided. Sometimes the first lower bicuspid has only
FORM OF PERMANENT TEETH. MOLARS. 783
one tubercle distinctly marked, i. e., the external, and in that case approaches
in figure to a canine tooth.
The molar teeth, true or large molars, or multicuspid teeth, are twelve
in number, and are arranged behind the bicuspid teeth, three on each
side, above and below. They are distinguished by the large size of the
crown, and by the great width of its grinding surface. The first molar
is the largest, and the third is the smallest, in each range, so as to pro-
duce a gradation of size in these teeth. The last molar in each range,
owing to its late appearance through the gums, is called the wisdom-
toothy dens sapientise. The crowns of the molar teeth are low and cuboid
in their general form. Their outer and inner surfaces are convex, but
the crowns are rather flattened before and behind. The grinding surface
it nearly square in the lower teeth, and rhomboid al in the upper, the
corners being rounded off : it is not smooth, but is provided with four or
five trihedral tubercles or cusps (whence the name of multicuspidati), sepa-
rated from each other by a crucial depression. The upper molars have
four cusps situated at the angles of the masticating surface ; of these the
internal and anterior cusp is the largest, and is frequently connected with
the posterior external cusp by a low oblique ridge. In the upper wisdom-
teeth, the two internal tubercles are usually blended together. The crowns
of the lower molars, which are larger than those of the upper, have five
cusps, the additional one being placed between the two posterior cusps, and
rather to the outer side : this is especially evident in the lower wisdom-
teeth, in which the crown is smaller and rounder than in the others. The
fangs of all the molar teeth are multiple. In the two anterior molars of
the upper jaw, they are three in number, viz. two placed externally, which
are short, divergent, and turned towards the antrum of the superior max-
illa ; and a third or internal fang, which is larger and longer, and is directed
towards the palate, the posterior border of which extends as far back as that
of the posterior external fang. This third fang is often slightly grooved,
especially when the two internal cusps are very distinct, and sometimes it
is divided into two smaller fangs. The two anterior molars of the lower
jaw have each two fangs, one anterior, the other posterior, which are broad,
compressed, and grooved on the faces that are turned towards each other,
as if each consisted of two fangs fused together : they have an inclination
or curve backwards in the jaw, and are slightly divergent, or sometimes
parallel, or even nearly in contact with each other : more rarely one or both
of them is divided into two smaller fangs. In the wisdom-teeth of both
jaws the fangs are often collected into a single irregular conical mass, which
is either directed backwards in the substance of the jaw, or curved irregu-
larly : this composite fang sometimes shows traces of subdivision, and there
are occasionally two fangs in the lower tooth and three in the upper.
The bicuspid and the molar teeth, from the breadth and uneven form of
their crowns, are fitted for bruising, crushing, and grinding the food in
mastication.
The range of teeth in each jaw forms a nearly uniform curve, which is
not broken by any intervals, as is the case in the dental apparatus of many
animals, even in the Quadrumana. The upper dental arch is rather wider
than the lower one, so that the teeth of the upper jaw slightly overhang
those of the lower. This is owing principally to the fact that the lower
teeth are placed either vertically, as in front, or are inclined somewhat
inwards, as is seen behind and at the sides, while the corresponding teeth
of the upper jaw have an inclination forwards in front, and outwards
784
ORGANS OF DIGESTION.
behind. While there is a slight diminution in the height of the exposed
parts of the teeth from the incisors backwards to the wisdom-teeth, there is
in man a general uniformity in the amount of projection of the crowns
throughout the whole series. In consequence of the large proportionate
breadth of the upper central incisors, the other teeth of the upper jaw are
thrown somewhat outwards, so that in closure of the jaws the canine and
bicuspid teeth come into contact partly with the corresponding lower teeth
and partly with those next following ; and in the case of the molar teeth,
each cusp of the upper lies behind the corresponding cusp of the lower
teeth. Since, however, the upper wisdom-teeth are smaller than those
below, the dental ranges terminate behind nearly at the same point in both
jaws.
The Milk-teeth. — The temporary incisor and canine teeth resemble those of
the permanent set in their general form ; but they are of smaller dimen-
sions. The temporary molar teeth present some peculiarities. The hinder
of the two is much the larger ; it is the largest of all the milk-teeth, and
is larger even than the second permanent bicuspid, by which it is afterwards
replaced. The crown of the first upper milk molar has only three cusps,
Fig. 542.
Fig. 542.— MILK TEETH OP THE RIGHT SIDE OF THE UPPER AND LOWER JAWS.
a, the incisors ; 6, the canines ; c, the molar teeth.
two external and one internal ; that of the second has four distinct cusps.
The first lower temporary molar has four cusps, and the second five, of which
in the latter case three are external. The fangs of the temporary molars
resemble those of the permanent set, but they are smaller, and are more
divergent from the neck of the tooth.
Structure. — On making a section of a tooth, the hard substance of
which it is composed is found to be hollow in the centre. The form of the
cavity bears a general resemblance to that of the tooth itself : it occupies the
interior of the crown, is widest opposite to or a little above the neck, and ex-
tends down each fang, at the point of which it opens by a small orifice. In
the crown of the incisor teeth the cavity is prolonged into two fine linear
canals, which proceed one to each corner of the crown ; in the bicuspid and
molar teeth it advances a short distance into each cusp. In the case of a root
formed by the blending of two or more fangs, as occurs occasionally in the
wisdom-teeth, each division has a separate canal prolonged down to its apex.
STRUCTURE OF THE DENTINE.
785
The central cavity of a tooth is called the pulp-cavity, because it is occupied
and accurately filled by a soft, highly vascular, and sensitive substance,
Fig. 543.
Fig. 543. — SECTIONS OP AN INCISOR AND
MOLAR TOOTH.
The longitudinal sections show the whole
of the pulp-cavity in the incisor and molar
teeth, its extension upwards within the crown
and its prolongation downwards into the fangs
with the small aperture at the point of each ;
these and the cross section show the relation
of the dentine and enamel.
called the dental pulp. This pulp con-
sists of areolar filaments, amongst
which numerous nuclei and cells are rendered visible by the action of acetic
acid. It is well supplied with vessels and nerves, which are derived from
Fig. 544. — MAGNIFIED LONGITUDINAL SECTION OF A Fig. 544.
BICUSPID TOOTH (after Ketzius).
1, the ivory or dentine, showing the direction and pri-
mary curves of the dental tubuli ; 2, the pulp-cavity with
the small apertures of the tubuli into it ; 3, the cement or
crusta petrosa covering the fang as high as the border of
the enamel at the neck, exhibiting lacunae ; 4, the enamel
resting on the dentine ; this has been worn away by use from
the upper part.
the internal maxillary artery and the fifth pair, and
which enter the cavity through the small aperture
at the point of each fang.
The solid portion of the tooth is composed of
three distinct substances, viz. the proper dental
substance, ivory or dentine, the enamel, and the
cement or crusta petrosa. The dentine constitutes
by far the larger part of the hard substance of a
tooth ; the enamel is found only upon the exposed
part or crown ; and the cement covers with a thin
layer the surface of the implanted portion or fang.
A fourth variety of tissue, osteodentine, is formed
within the dentine, at the expense of the pulp, as
age advances.
A. The dentine, (Owen,) forming the principal
mass or foundation of the body and root of a tooth,
gives to both of these parts their general form,
and immediately encloses the central cavity. It
resembles very compact bone in its general aspect and chemical relations,
but is not identical with it in structure, or in the exact proportions of its
earthy and animal constituents.
According to the analyses of Berzelius and Bibra, the dentine of human
teeth consists of 28 parts per cent, of animal, aud 72 of earthy matter.
The former is resolvable into gelatin by boiling. The composition of the
latter, according to Bibra, is as follows, viz. , phosphate of lime 66 '7 per cent.,
carbonate of lime 3 '3, phosphate of magnesia and other salts, including a
trace of fluoride of calcium, !• 8. Berzelius found 5 *3 carbonate of lime.
3 F
786
THE TEETH.
Examined under the micro-
scope, dentine is seen to consist
of an immense number of very
fine tubes, imbedded closely
together in a hard intertubular
matrix, and having the appear-
ance of possessing distinct parie-
tes. These dental tubules open
at their inner ends into the pulp-
cavity, the wall of which pre-
sents very numerous minute ori-
fices over the whole of its inner
surface. Fruin thence they
pass in a radiated manner
Fig. 545. — SECTIONS OP DENTINE
(from Kolliker).
A, highly magnified cross sections of
the tubuli of dentine. ±f-. a, from
a part in which the tubuli are very
closely set ; b, from a part where
they are widely set.
B, longitudinal section of the root.
2fQ a, the dental tubes near the inner
surface of the dentine with few tubuli ;
6, subdivision of tubuli ; c, looped
disposition of the tubuli ; d, granular
layer consisting of small dental glo-
bules at the margin of the dentine ;
e, lacunas of the cement, one of them
connected by tubuli with those of the
dentine.
through every part of the ivory
towards its periphery. In the
upper portion of the crown they
have a vertical direction ; but
towards the sides, and in the
neck and root, they become
gradually oblique, then hori-
zontal, and are finally even in-
clined downwards towards the
point of the fang. The course
of the tubules is not straight,
but each describes, in passing
from the central to the peri-
pheral part of the dentine, two
or three gentle curves' (primary
curvatures, Owen), and is be-
sides bent throughout its whole
length into numerous fine undu-
lations, which follow closely one
upon another ; these are the
secondary curvatures. The cur-
vatures of adjacent tubules so
THE DENTAL TUBULES. 787
far correspond, that the tubes are on the whole nearly parallel, being only
slightly divergent as they pass towards the surface ; and as they divide
several times dichotomously, and at first without being much diminished in
size, they continue to occupy the substance of the dentine with nearly equi-
distant tubes, and thus produce, when seen in fine sections of the tooth
made parallel to their course, a striated appearance, as if the dentine were
made up of fine parallel fibres. The concurrence of many of these parallel
curvatures of the dental tubuli produces, by the manner in which they
reflect the light, an appearance of concentric undulations in the dentine,
which may be well seen with a low magnifying power. This, however, is
not to be confounded with another set of curved marks called contour lines,
which depend on conditions of the matrix, and will be afterwards described.
The average diameter of each tubule near its inner and larger end is -j^^th
of an inch, and the distance between adjacent tubules is about two or three
times their width. (Retzius.) From their sides numerous immeasurably
fine branches are given off, which penetrate the hard iutertubular substance,
where they either anastomose or terminate blindly. These lateral ramuscles
are said to be more abundant in the fang. Near the periphery of the ivory
they are very numerous, and, together with the main tubules themselves,
which there, by rapid division and subdivision, also become very fine, ter-
minate by joining together in loops, or end in little dilatations, or in the
cells of the granular layer to be described.
The dental tubules, when highly magnified, appear like dark lines against
transmitted light, but are white when seen upon a black ground. Their
tubular character is proved by the fact that ink, or other coloured fluids,
together with minute bells of air, can be made to pass along them, in sec-
tions of dry teeth. Their walls, in transverse sections, may often appear
thicker than they are in reality, owing to a certain length of the tubes being
seen in the section : but if the orifice of the canal be brought exactly into
focus, the wall appears as only a very thin, yellowish border ; and, indeed,
Kolliker denies the existence of any wall distinct from the matrix. From
the researches of Nasmyth, Tomes, and Kolliker, it appears that in the
recent state the tubules are filled with substance (dental fibres), continuous
with the pulp of the tooth : and it is suggested by Tomes that this is not
only subservient to the nutrition of the dentine, but probably also confers
on it a certain degree of sensibility. It has been noticed, indeed, that the
dentine is more sensitive near the surface than deeper in its substance, — a
fact not easily intelligible on the supposition that the sentient tissue is
confined to the pulp-cavity.
In the temporary, and sometimes even in the permanent teeth, the tubules are
constricted at short intervals, so as to present a moniliform character. The terminal
branches of tubules are occasionally seen to pass on into the cement which covers the
fang, and to communicate with the small ramified canals of the characteristic lacunas
found in that osseous layer. Tubules have likewise been observed by Tomes passing
on into the enamel, more especially in the teeth of marsupial animals, but in a less
marked degree in human teeth.
The intertubular substance is translucent. The animal matter which
remains in it, after the earthy matter has been removed by an acid,
exhibits a tendency to tear in the direction of the tubules, but is in reality
a homogeneous substance, deposited in a laminated manner. This was
shown by Sharpey, who observed that in the softened teeth of the cachalot
or sperm-whale the animal substance was readily torn into fine lamellae,
disposed parallelly with the internal surface of the pulp-cavity, and there-
* 3 F 2
788
THE TEETH.
fore across the direction of the tubules. In these lamellse the sections of
the tubules appeared as round or oval apertures, the lamellae having the
same relation to the tubules as those of true bone to the canaliculi. The
same tendency to lamination may be exhibited by boiling a longitudinal
section of tooth with caustic potash, after which it presents closely set, short,
and regular fissures, lying at right angles to the tubules, throughout the
extent of the dentine. (Cleland.)
Fu. 546.
~e
Fig. 546. — VERTICAL SECTION OP THE UPPER
PART OF AN INCISOR TOOTH (from Kol-
liker). f
a, the pulp-cavity ; b, dentine or tubular
substance ; c, arched contour lines with inter-
globular spaces ; d, cement ; e, cuamel with
an indication of the direction of the columns ;
/, coloured lines of the enamel.
Fig. 547. — A SMALL PORTION OP THE DENTINE
WITH INTEHGLOBULAR SPACES (from K61-
liker). 3f
6, the tubules ; c, the interglobular spaces
filled with air.
A laminated structure of a more distinct description has been observed
in the dentine of the crown, giving rise to the appearances in longitudinal
sections termed contour lines. Czermak states that transverse sections of
the tooth present concentric lines resembling the year-rings of wood : and
Salter has shown that decalcified specimens readily break up in these lines ;
the crowns of the teeth consisting of a series of superimposed hollow
cones : the intervals between their strata, in longitudinal sections, appearing
as contour markings, in transverse sections as annular lines ; in both cases
corresponding with the surface of the pulp, as it existed during the forma-
tion of the tooth. The contour markings, when examined with the micro-
scope, are seen to be caused by irregularities of the intertubular tissue,
which, opposite these marks, presents the appearance of spaces or clefts
bounded by globular masses of the ordinary tubular and dense substance.
These globules vary in size from -^oth to TQ^TTO^ °f an *ncn 5 tne largest
being in the crown, the smallest in the fang. The tubuli pass through these
globules, and appear to be continuous in direction across the interspaces
from one globule to another.
STRUCTURE OF THE EXAMEL,
789
Another kind of irregularity in the structure of the dentine gives rise to
the granular layer of Purkinje ; the peculiarity of which consists in the
presence of a number of minute cell-like cavities, which break up the
uniformity of the matrix, and by branches anastomose one with another
and receive terminations of dental tubuli. They are found principally in
a layer beneath the cement, and also beneath the enamel. The circum-
stance of their forming connections with the tubules points to a difference
in nature between these cavities and the much larger iuterglobular spaces.
The surface of the dentine where it is in con-
tact with the enamel is marked by undulating
grooves and ridges, and also by numerous minute
hexagonal depressions, to which the microscopic
fibres of the enamel are accurately adapted.
B. The enamel is that hard white covering
which encrusts and protects the exposed portion
or crown of a tooth. It is the hardest of all the
dental tissues, but it is gradually worn down by
protracted use. It is thickest on the grinding
surface and cutting edges of the teeth, and be-
comes gradually thinner towards the neck, where
it ceases. Its extent and thickness are readily
Fig. 548. — THIN SECTION OF THE ENAMEL AND A PART
OF THE DENTINE (from Kb'lliker). rf°
a, cuticular pellicle of the enamel ; 6, enamel-fibres or
columns with fissures between them and cross striae ; c,
larger cavities in the enamel communicating with the
extremities of some of the tubuli (d).
seen on charring the tooth, by which the dentine
becomes blackened, whilst the enamel, owing to
the very small quantity of animal matter in its
composition, remains white. According to Bibra
it contains of earthy constituents 96 '5 per cent.,
viz. phosphate of lime with traces of fluoride of
calcium 89 '8, carbonate of lime 4 -4, phosphate
of magnesia and other salts 1'3 ; and has only
3-5 per cent, of animal matter. Berzelius, however, gives the proportion
of carbonate of lime as 8, and of animal matter as only 2 per cent.
The enamel is made up entirely of very hard and dense microscopic fibres
or prisms, composed almost wholly of earthy matter, arranged closely to-
gether, side by side, and set by one extremity upon the subjacent surface of
the dentine. On the summit of the coronal portion of the tooth these
enamel fibres are directed vertically, but on the sides they are nearly hori-
zontal. As seen in a section they are disposed in gently waving lines,
parallel with each other, but not so regular as the curvatures of the tubuli
of the dentine, with which they have no agreement. The concurrence of
these parallel curvatures produces, as in the case of the dentine, an appear-
ance of concentric undulations in the enamel, which may be seen with a
lens of low power. A series of concentric lines is likewise to be seen
crossing the enamel fibres, as the contour lines cross the dentine : these are
termed coloured lines from their brown appearance, but they seem rather to
depend on lamination than on pigmentary deposit. Minute fissures not
unfrequently exist in the deep part of the enamel, which run between
790
THE TEETH.
clusters of the fibres down to the surface of the dentine ; and other much
larger and more evident fissures are often observed leading down from the
depressions or crevices between the cusps of the molar and premolar teeth.
The surface of the enamel, especially in the milk-teeth, is marked by
transverse ridges, which may be distinguished with a common magnifying
glass.
Fig. 549.
Fig. 549.— ENAMEL FIBRES (from Kolliker). sf°
A, fragments and single fibres of the enamel, isolated by the action of hydrochloric acid.
B, surface of a small fragment of enamel, showing the hexagonal ends of the fibres.
The enamel-fibres have the form of solid hexagonal prisms. Their dia-
meter varies slightly, and is ordinarily about j^o^th of an inch. They are
marked at small intervals by dark transverse lines. According to Tomes,
the fibre is not in all cases solid, but has occasionally an extremely minute
cavity in part or in the whole of its length, which is best seen in newly-
developed enamel, but is also visible in adult teeth. The inner ends of the
prisms are implanted, as it were, into the minute hexagonal depressions
found on the surface of the dentine, whilst the outer ends, somewhat larger
in diameter, are free, and present, when examined with a high magnifying
power, a tesselated appearance.
When submitted to the action of dilute acids, the enamel is almost
entirely dissolved, and leaves scarcely any discernible traces of animal
matter. Near the deep surface this is rather more abundant, according to
the observations of Retains, who conceived that it there aided in fixing the
enamel fibres. By the action of an acid, the enamel of newly formed or
still growing teeth may be broken up, and its structural elements more
easily distinguished. The prisms are then found to have interposed between
them a delicate membranous structure, forming sheaths in which the cal-
careous matter is deposited. As this latter accumulates, the membranous
structure becomes almost or entirely obliterated, and the now earthy prisms
are inseparably consolidated. Each membranous sheath, according to Tomes,
contains a line of granular cells or masses, arranged in single series like the
sarcous elements in muscular fibres, and thus occasioning the transverse
markings.
STRUCTURE OF THE CEMENT.
791
It is also found, on treatment with acid, that a very thin membrane
called by Kolliker "cuticle of the enamel," — and by Busk and Huxley
" Nasmyth's membrane, " (after its discoverer), entirely covers the enamel upon
its outer surface. This membrane, which is calcined in the natural state,
forms a protective covering to the enamel. Berzelius and Retzius say that
a similar membrane also exists between the enamel and the dentine, but
Kolliker has been unable to find any in that situation.
c. The crusta petrosa or cement is the third substance which enters into
the formation of the teeth. This is a layer of true bone, slightly modified
in structure, and investing that part of the dentine which is not protected
by the enamel. It covers the whole fang, towards the lower end of which
it becomes gradually thicker, and is especially developed at the apex, and
along the grooves of the compound fangs. Besides this, the calcified mem-
brane or cuticle on the surface of the enamel has been regarded by various
writers as a coating of cement iu that situation, the representative of the
coronal cement on the compound teeth of many herbivorous animals. As
life advances, the cement generally becomes thicker, especially near the
apex of the fang, where it sometimes blocks up the orifice leading into the
pulp-cavity.
The crusta petrosa contains cells and canaliculi resembling those of bone ;
they are placed lengthwise around the fang, and give off minute radiated
ramifications, which are often found to proceed from one side only of a cell,
towards the periodontal surface (Tomes). In the deeper layers of the
cement the fine canaliculi sometimes anastomose with some of the terminal
tubules of the subjacent dentine. Where the cement is very thick it may
contain vascular canals, analogous to the Haversian canals of bone. On the
deciduous teeth the cement is thinner, and contains fewer cells. It has been
shown by Sharpey that perforating fibres, similar to those of ordinary bone,
run abundantly through the cement. In chemical composition it resembles
bone, and contains 30 per cent, of animal matter. The cement is, according
to some, extremely sensitive at the neck of the tooth, if it be exposed by
Fig. 550. — SECTION OP A PORTION OP THE DENTINE AND CKMENT FROM THE MIDDLE OF
THE ROOT OP AN INCISOR TOOTH (from Kolliker). 3f°
a, dental tubuli ramifying and terminating, some of them in the interglobular spaces
(b and c), which resemble somewhat bone-laeunse ; d, inner layer of the cement witl\
numerous closely set canaliculi ; e, outer layer of cement; /, lacunce ; y, canaliculi.
792 THE TEETH.
retraction of the gum. By its connection with the surrounding mem-
branous structures it contributes to fix the tooth in the socket. It is the
seat of the bony growths or exostoses sometimes found upon the teeth.
D. Osteodentine (Owen), secondary dentine (Tomes), or the horny substance
of Blumenbach, is a hard substance which begins to be deposited on the
inner surface of the dentine after the age of twenty years or later, so that
the central cavity of a tooth becomes gradually diminished in size, whilst
the pulp slowly shrinks or disappears. This additional substance, formerly
regarded as an extension of the cement into the interior of the tooth, has
been shown to have a distinct structure, in part resembling dentine, and in
part bone. It is traversed by canals, which contain blood-vessels, and are
surrounded by concentric lamellae, like the Haversian canals of bone. From
these canals, numerous tubules radiate in all directions, larger than the
canaliculi of bone, resembling, in this respect, and also in their mode of
ramification, the tubes of the dentine. This newly added structure may or
may not coalesce with the previously formed dentine ; it appears to be pro-
duced by a slow conversion of the dental pulp.
Among special works on the teeth may be noticed, Retzius, in Muller's Archiv,
1837; Nasmytk, Researches on the Teeth, 1839; Owen, Odontography, 1840-45;
Tomes, Lectures on Dental Physiology and Surgery, 1848, also in the Phil.
Transactions, 1849 and 1850, and in Quart. Journ. of Micr. Science, 1856; Salter,
in Quarterly Journal of Microscopic Science, 1853, in Guy's Hospital Reports, third
series, vol. i. ; and in Trans. Path. Soc., 1854 and 1855 ; Czermak in Zeitschrift fur
wissensch. Zoologie, 1850; Huxley in Quarterly Journal of Microscopic Science, 1853.
DEVELOPMENT OP THE TEETH.
Although the general phenomena of the growth and succession of the
teeth had received considerable attention from various anatomists, the ob-
servations of Arnold and Goodsir, made independently of each other, more
especially the latter, were the first to give precision to our knowledge
concerning their origin and the earlier stages of their formation. More
recent researches have, it is true, shown that their account of the primor-
dial condition of the dental germs may require some modification ; but
nevertheless these authors were the first to establish the primordial con-
nection of the teeth with the mucous membrane covering the edges of the
maxillary arches, and Goodsir was the first to give a consistent view of the
earlier steps of the formative process in the temporary and permanent series
of teeth. (Arnold in Salzbtirger Med. Zeitung, 1831 ; Goodsir in Edin.
Med. and Surg. Journal, 1839.) The changes which take place in the
bones of the jaws relate only to the formation of the sockets of the teeth.
In their earliest condition these bones present no appearance of alveoli,
but, concurrently with certain changes in the mucous membrane, to be
immediately described, a wide groove is developed aloi.'g the edge of the jaw,
which gradually becomes deeper, and is at length divided across by thin
bony partitions, so as to form a series of four-sided cells. These bony septa
are not distinctly formed until near the fifth month of foetal life. By the
subsequent growth of the bone, these cavities or loculi are gradually closed
round, except where they remain open at the edge of the jaw. By the end
of the sixth month they are distinctly formed, but continue afterwards, in
proportion to the growth of the teeth, to increase in size and depth, by the
addition of new matter which widens and deepens the jaw.
The first stages in the development of the teeth, as observed by Arnold
and Goodsir, consist of certain changes in the mucous membrane cover-
DEVELOPMENT OF THE TEETH. 793
ing the borders of the maxilloe. About the sixth week of embryonic life,
a depression or groove, having the form of a horse- shoe, appears along
the edge of the jaw, in the mucous membrane of the gum ; this is the
primitive dental groove (Goodsir), From the floor of this groove (supposed
to be represented in a transverse section, in the diagrammatic figure 551,1)
Fig. 551.
/IS1
Fig. 551. — DIAGRAMMATIC OUTLINES OP SECTIONS THROUGH THE DENTAL GERMS AND
SACS, AT DIFFERENT STAGES OF DEVELOPMENT (from Goodsir).
1, the primitive dental groove of the gum cut across in a foetus of about six weeks; 2,
a papilla rising within the dental groove ; 3, 4, and 5, represent the follicular stage in
which the papilla (or future tooth-pulp) is seen sunk within the follicle, and the lips of
the follicle or opercula advancing towards each other gradually meet and close in the ful-
licle; 5, may be looked upon as representing the section indicated by the line a b, in fig.
559, through the sac of an incisor tooth, in which a lunated depression (c) is left behind;
in 6, the lips of the groove are seen to come together ; in 7, the union of the lips being
complete, the follicle becomes a closed sac s, containing the dental pulp p, and having
behind it the lunated depression c, now also enclosed, and forming the cavity of reserve
for the germ of the corresponding permanent tooth ; in the remaining outlines, 8 to 12,
are shown the commencement of the cap of dentine on the pulp, the subsequent steps in
the formation of the milk tooth, and its eruption through the gum (11); also the gradual
changes in the cavity of reserve, the appearance of its laminae and papilla, its closure to
form the sac of the permanent tooth, its descent into the jaw, behind and below the milk
tooth, and the long pedicle (12) formed by its upper obliterated portion.
a series of ten papillae, as at 2, arise in succession in each jaw, and consti-
tute the germs or rudimentary pulps of the milk-teeth. These pulps or
papillae are processes of the mucous membrane itself, and not mere eleva-
tions of its epithelium. The order in which they appear is very regular.
The earliest is that for the first milk molar tooth : it is seen at the seventh
week, as soon as the dental groove is formed ; at the eighth week that for
the canine tooth appears ; the two incisor papillae follow next, at about the
ninth week, the central one before the lateral ; lastly, the second molar
papilla is visible at the tenth week, at which period this, the papillary stage
of the rudiments of the teeth is completed. The papillae in the upper jaw
appear a little earlier than those in the lower jaw. — In the next place, the
margins of the dental groove become thickened and prominent, especially
the inner one ; and membranous septa or prolongations of the mucous mem-
brane pass across between the papillae from one margin to the other, so as
to convert the bottom of the groove into a series of follicles, each containing
one of the papillae. These changes constitute the follicular stage ; they take
place in the same order as that in which the papillae make their appearance,
and are completed about the fourteenth week. During the early part of this
794 THE TEETH.
period the papillce grow rapidly, they begin to show peculiarities of form, and
project from the mouths of the follicles. Soon, however, the follicles become
deeper, so as to hide the papillae, which now assume a shape corresponding
with that of the crowns of the future teeth. Small laminae or opercula of
membrane are then developed from the sides of each follicle, their number
and position being regulated, it is said, by the form of the cutting edges
and tubercles of the coming teeth : the incisor follicles having two laminae,
one external and one internal ; the canine, three, of which two are internal ;
and the molars, four or five each. — The lips of the dental groove, as well as
the opercula, now begin to cohere over the follicles from behind forwards,
the posterior lip being very much thickened ; the groove itself ia thus
Fig. 552. Fig. 552.— ENLARGED VIEW OP THE UPPER AND
LOWER DENT\L ARCHES OP A FCETUS OP ABOUT
FOURTEEN WEEKS.
This specimen shows the follicular stage of develop-
ment of all the milk teeth as described by Goodsir ;
in each follicle the papilla is seen projecting ; but this
exposure of the papillae and the cavity of the follicles
probably arises from the accidental loss of the epithe-
lial covering.
gradually obliterated, the follicles are con-
verted into close sacs, and the saccular stage
of the milk-teeth is thus completed about the
end of the fifteenth week. Certain lunated
depressions, which are formed one behind each
of the milk -follicles about the fourteenth week,
escape the general adhesion of the lips of the
groove. From these depressions, as will b'e afterwards described, the sacs
of the ten anterior permanent teeth are subsequently developed.
The first stages in the development of the teeth here described, the superficial origin
and open condition of the dental sacs, and the free papillary commencement of the
pulps, have been denied in recent years by Guillot, and by Robin and Magitot, who
assert that the sacs with their contents make their first appearance in the submucous
tissue, and are from the first closed sacs (Guillot in Annales des Sciences Naturelles,
vol. ix., 1859; Robin and Magitot in Journal de la Physiologic, 1860, vol. iii., pp.
130 and 663). The observations of Kolliker, however, seem to furnish a clue to the
explanation of what has been seen by these authors, at the same time that they con-
firm, in its most important features, Goodsir's mode of viewing the phenomena. In
the foetal lamb and calf, the first step in the formation of the tooth-germ, observed by
Kolliker, consists in a depression of a part of the deepest layer of the epithelium
into the subjacent mucous membrane. This depression, which, in common with
Huxley, he regards as the commencement of the foetal structure known as the enamel
organ, to be afterwards described, widens subsequently, so as to become flask-shaped,
remaining connected with the deep surface of the epithelium by a narrow neck. In
the next stage the dental papilla rising from the surface of the mucous membrane,
projects into, or indents the deepest side of the epithelial process or future enamel
organ, and the dental sac is formed at a somewhat later period in the surrounding
substance of the mucous membrane. In these animals, therefore, the epithelium of
the edge of the jaw covers in completely the enamel-germ or primary tooth-follicle.
In man, Kolliker was unable to discover a similar arrangement, but found matters
very much, in the disposition described by Goodsir; that is, the follicles open, situated
in a dental groove of the jaw, and containing at their deepest part the dental papilke
developed from the mucous membrane. But he conceives it not improbable that in
Goodsir's specimens, as well aa in his own, the whole of the epithelium had been
abraded, and that the follicles and papillae were thus unnaturally opened to the surface.
ORIGIN OF THE DENTAL GERMS.
795
Fig. 553. — DIAGRAMS OF THE MODE OP
ORIGIN OF THR DENTAL GEKM IN
THE RUMINANT (after Kolliker).
The three figures represent trans-
Terse sections of the gum and a part of
the jaw at or shortly after the period
of the formation of the germ, and are
designed chiefly to show the relation of
the germ to the epithelium.
A, represents the state in a very
early condition, when the primitive
deutal follicle of a milk or temporary
tooth has been formed by a depression
from the deep layer of the epithe-
lium.
B, represents a later stage, when the
tooth-papilla has risen from the surface
of the mucous membrane, and has
inflected the primitive dental follicle.
C, represents a more advanced stage
in which the dental sac has begun to
be formed.
c, the superficial thick epithelium of
the gum only sketched in outline ; c',
the deep layer of cylindrical cells ; /,
the primitive tooth -follicle ; /', its cel-
lular or granular contents and cavity ;
p, the dental papilla, and afterwards
tooth-pulp ; e, the inner inflected layer
of the wall of the primitive follicle
forming the inner part of the enamel
organ ; e', the outer wall of the same
with the epithelial sprouts shooting into
the tissue above ; s, the commencement
of the dental sac ; fp, the follicle of
the corresponding permanent tooth.
Waldeyer has shown by more
recent observations, that in the
human embryo the teeth arise in a
manner essentially the same as that
described by Kolliker in the rumi-
nant. (Waldeyer, lib. die Entwick.
<ler ZShne, Zeitsch. fur. ration. Me-
dicin, 1865, and Henle's Bericht, &c.
for 1864, p. 81.)
The dental sacs, after the
closure of the follicles, continue
to enlarge, as do also their con-
tained papillae. The walls of
the sacs, which soon begin to
thicken, consist of an outer tibro-
areolar membrane, and an in-
ternal highly vascular layer,
lined by epithelium ; their blood-
vessels are derived partly from
the dental arteries which course
along the base of the sacs, and
partly from those of the gums.
The papillse, now the dental
pulps, acquire a perfect resem-
Fig. 553.
796 THE TEETH.
blance to the crowns of the future teeth, and then the formation of the
hard substance commences in them. This process begins very early, and by
the end of the fourth month of foetal life thin shells or caps of dentine are
found on all the pulps of the milk-teeth, and a little later on that of the
first permanent molar, while at the same time the coating of enamel begins
to be deposited on each. The cap of dentine increases in extent by a growth
around its edges, and in thickness by additions in its interior, at the expense
of the substance of the pulp itself, which decreases in proportion. Thia
growth of the tooth continues until the crown is completed of its proper
width, and then the pulp undergoes a constriction at its base to form the
cervix of the tooth, and afterwards elongates and becomes narrower, so as to
serve as the basis of the fang. Sooner or later, after the completion of the
crown, this part of the tooth appears through the gum, whilst the growth of
dentine to complete the fang is continued at the surface of the elongating
pulp, which gradually becomes encroached upon by successive formations of
hard substance, until only a small cavity is left in the centre of the tooth,
containing nothing but the reduced pulp, supplied by slender threads of
vessels and nerves, which enter by a small aperture left at the point of the
fang after the dentine is completed. In the case of teeth having complex
crowns and more than a single fang, the process is somewhat modified. On
the surface of the dental pulp of such a tooth, as many separate caps or
shells of dental substance are formed as there are eminences or points ; these
soon coalesce, and the formation of the tooth proceeds as before as far as the
cervix. The pulp then becomes divided into two or more portions, corres-
ponding with the future fangs, and the ossification advances in each as it
does in a single fang. A horizontal projection or bridge of dentine shoots
across the base of the pulp, between the commencing fangs, so that if the
tooth be removed at this stage and examined on its under surface, its shell
presents as many apertures as there are separate fangs. In alt teeth, the
pulp originally adheres by its entire base to the bottom of the sac ; but, when
more than one fang is to be developed, the pulp is, as it were, separated
from the sac in certain parts, so that it comes to adhere at two or three in-
sulated points only, whilst the dentine continues to be formed along the
intermediate and surrounding free surface of the pulp.
Formation of the hard tissues of the teeth. — Previously to the commencement of
ossification, the primitive pulp is found to consist of microscopic nucleated cells
(pulp-granules, Purkinje), more or less rounded in form, and imbedded in a clear
Fig. 554. — DIFFERENT STAGES IN TTTE FORMATION OF A MOLAR TOOTH WITH Two
FANGS (from Blake).
1, the distinct caps of dentine for five crowns in the earliest stage of formation ; in 2,
and the remaining figures, the crown is downwards ; in 2 and 3, the formation of the
crown having proceeded as far as the neck, a bridge of dentine stretches across the base
of the tooth-pulp ; and in 4, the division of the fangs is thus completed ; in 5, 6, and 7,
the extension takes place in the fangs.
FORMATION OF THE DEXTAL SUBSTANCES.
797
matrix containing a few very fine molecules, thinly disseminated in it. At the
exterior of the pulp, the cells become elongated, and arranged perpendicularly to the
Fig. 555. — VERTICAL TRANSVERSE SEC- Pig 555^
TION OF THE DENTAL SAC, PULP, &C. ,
OF A KITTEN (from Kolliker after a
preparation by Tiersch). \*
a, dental papilla or pulp, the outer
darker part consisting of the dentine
cells ; 6, the cap of dentine formed upon
the summit ; c, its covering of enamel ;
d, inner layer of epithelium of the
enamel organ ; e, gelatinous tissue ; /,
outer epithelial layer of the enamel
organ ; g, inner layer, and h, outer
layer of the dental sac.
surface, so as to form a tolerably regular
layer, resembling a columnar epi-
thelium. The pulp contains white
areolar fibres, without any elastic or
yellow tissue, and it is highly vascular.
The capillary vessels are most abun-
dant at the points where ossification
is to commence ; they form a series of
loops between rows of cells arranged
in a radiate manner, but they do not
reach the surface. Besides this, the
entire pulp is covered by a fine pellucid
homogeneous membrane, named the
preformative membrane (Purkinje,
Raschkow), or basement membrane.
The space between the pulp and the
wall of the sac is occupied by a delicate substance accurately applied to its surface.
This is the outer pulp of Hunter, termed also the enamel-organ (organon adamantines,
Purkinje), being generally considered to be connected with the formation of the enamel.
It presents three layers ; viz., externally, an epithelial layer with prominences which
fit in between vascular processes of the surrounding mucous membrane ; internally, a
layer of cylindrical nucleated cells, named the enamel-membrane, resting on the pre-
formative membrane ; and between these, a bulky substance, consisting of small stellate
cells anastomosing by long processes, and having the large meshes between them filled
with clear fluid. This structure was formerly supposed to be similar to the primitive
pulp ; but, as was first stated by Huxley and since confirmed by Kolliker, the whole
enamel-organ is epithelial in nature, being derived by invagination from the cuticle.
The dentine is formed at the surface of the pulp, beneath the preformative mem-
brane, but the precise manner in which it is derived from the soft tissues is still
a matter for investigation, According to Purkinje, Retzius, and Raschkow, the
preformative membrane is the part which first undergoes calcification, and after-
wards the tissue of the pulp immediately beneath it. On gently separating the
newly formed cap of dentine from the formative pulp, in the growing teeth of the
human subject or of animals, and examining it under the microscope, the elongated
cells of the pulp are found adhering in numbers to the inner surface of the newly-
formed dentine. Owen states that the nuclei of the elongated cells, having them-
selves become lengthened, divide both longitudinally and transversely to develop
secondary cells which continue included within the primary cells. The secondary
cells then elongate, and together with their nuclei join end to end. Calcification
proceeds in all parts, except in the nuclei of the secondary cells which remain as
the cavities or lumina of the tubes ; the walls of the secondary cells are supposed
to form the parietes of the tubes, and the material between the secondary cells
together with the walls of the primary cells to be converted into the intertubular sub-
stance. The bifurcation of the tubuli is said to result from the junction of two
798
THE TEETH.
secondary cells with a single one in a deeper layer of the pulp ; and the constricted or
moniliform appearance of the tubuli already mentioned as having been seen by some
observers in growing or even in mature teeth, is thought to depend on an imperfect
Fig. 556.
Fig. 556. — VERTICAL SECTION THROUGH THE POINT OF A HUMAN FOETAL MILK TOOTH, IN
WHICH THE FORMATION OF THE DENTINE AND ENAMEL HAS RECENTLY COMMENCED (from
Kolliker after Lent). ^
a, dental pulp with blood-vessels ; 5, the dentine-cells upon its surface ; c, the cap of
dentine which has been formed on the summit, the tubuli being shown as prolongations
from the tapering extremities of the dentine-cells ; d, the enamel begun to be deposited ;
c, membranous layer, mernbrana prseformativa of Huxley.
coalescence of the nuclei. In the teeth of young animals, Tomes has noticed the
division of the cells and their subsequent coalescence to form the tubes, but he has
failed to recognise the existence of primary cells including secondary ones. Lent
finds that the superficial elongated cells of the dentinal pulp send off from their
free ends long slender processes which form the tubes of the dentine, and which divide
into branches, and anastomose together in the same manner as the tubes. Kolliker,
who confirms Lent's observations, thinks it probable that a single cell may generate a
tube in its whole length ; at the same time a cell is sometimes constricted or incom-
pletely divided into two, the more superficial of which becomes narrowed and length-
ened into the dentinal tube.
With respect to the actual formation of the hard substance of the tooth, two views
have been entertained ; Kolliker conceiving it to proceed from the calcification of a
soft matrix excreted from the dentinal cells and their thin prolongations already
referred to ; whereas Waldeyer, who denies the existence of a preformative mem-
brane, maintains that the formation of the dentine consists in the conversion of a part
of the protoplasm of the dentinal cells into a collagenous substance, which is subse-
quently calcified, while the remaining part of the cell-protoplasm continues in the
form of soft fibres to occupy the interior of the tube surrounded by the calcified sub-
stance. (Op. cit. p. 189.) When the cap of dentine is examined in the newly formed
state, besides the ordinary dentine, globules are commonly observed ; but, if diluted
hydrochloric acid be added, the globules disappear. Hence Czermak concludes that
earthy impregnation proceeds for a time in a globular form, and that the after-
presence of globular dentine is the result of arrested development; perfect develop-
ment leading to the filling up of the spaces between the globules, and to the pro-
duction of an uniformly compact tissue.
The enamel appears in the form of prismatic fibres which, until the point was con-
tested by Huxley, have been generally supposed to be produced by calcification of the
cells of the enamel-membrane, with which they correspond in figure. An enamel
fibre may be formed by a single cell growing in length, while its previously formed
FORMATION OF THE ENAMEL.
799
Fig. 557.
portion becomes calcified, or by the union of a series of successively formed cells
arranged vertically to the surface. During its formation the enamel is soft and
chalky, and can easily be separated into its com-
ponent prisms. Afterwards the membranous por-
tion of it is nearly all obliterated, and the nuclei
entirely disappear, or, according to Tomes, elongate
Fig. 557. — A SECTION THROUGH THE ENAMEL ORGAN
AND DENTAL SAC FROM THE TOOTH OP A CHILD AT
BIRTH (from Kolliker). sp
a, outer dense layer of the dental sac ; 6, inner
looser texture of the same with capillary blood-vessels
and a somewhat denser layer towards the enamel
organ ; c, spongy substance ; d, inner cells ; and
e, outer cellular layer of the enamel-organ.
B, four cells of the enamel-membrane. Sf2
into a very fine central canal in each fibre. It is
observed by Huxley that, if the pulp be treated
with acetic acid, a voluminous, transparent mem-
brane is raised from the whole surface in large folds,
and that the ends of the enamel fibres are to be
seen beneath it. The membrane is from -reV-a^h
to -r^jth of an inch in thickness ; is clear, trans-
parent, and exhibits little ridges bounding oval or
quadrangular spaces ; and is, according to him,
continuous with the membrana praeformativa.
Huxley, therefore, considers that the enamel appears
between the dentine and the preformative mem-
brane, and that the enamel-organ takes no part
in its formation. Tomes confirms the observation
of Huxley with regard to the separability of this
apparent membrane by acetic acid ; but, upon
closer examination, finds that it may be split into
columns, which are, in conformity with his view of
the structure of enamel, sheaths containing nuclei.
Tomes, further, believes that these sheaths may be
seen to pass through the membrane, which Huxley
describes as limiting them superficially ; and that,
consequently, it is not, as Huxley imagines, the
membrana praeformativa. "Waldeyer holds that the
membrane described by Huxley between the
enamel and the enamel-organ is only a layer of the
most recently formed enamel, as he finds it pos-
sible always to detect enamel-cells with the ends
partially calcified. He returns, therefore, to
Schwann's original view, that the formation of the
enamel-columns is due to the direct calcification of
the enamel-cell?* (Henle's Bericht, &c. for 1864,
p. 81, and op. cit.)
The Cement appears to be formed simultaneously
with the dentine of the fang by the periodontal
membrane.
Eruption of the temporary teeth. — At the
time of birth the crowns of the anterior milk-
teeth, still enclosed in their sacs, are com-
pleted within the jaw, and their fangs begin
to be formed. Their appearance through the gums follows a regular order,
but the period at which each pair of teeth is cut varies within certain
800
THE TEETH.
limits. The eruption commences at the age of eeven months, and is com-
pleted about the end of the second year. It begins with the central incisors
Fig. 558.
Fig. 558. —THE DENTAL
SACS EXPOSED IN THE JAW
OF A CHILD AT BIRTH.
a, the left half seen from
the inner side ; b, the right
half seen from the outer
side ; part of the hone has
been removed so as to ex-
pose the dental sacs as they
lie below the gum ; the
lower figure shows the sacs
of the milk-teeth and the
first permanent molar, ex-
posed by removing the bone
from the outside ; the upper
figure shows the same from
the inside, together with the
pediculated sacs of the per-
manent incisor and canine
teeth adhering to the gum.
of the lower jaw, which
are immediately followed
by those of the upper jaw ; and, as a general rule, each of the lower range of
teeth rises through the gum before the corresponding tooth of the upper set.
The following scheme indicates, in months, the order and time of eruption of
the milk-teeth.
MOLARS.
CANINES.
INCISORS.
CANINES.
24 12
18
9779
18
12 24
Before the teeth protrude through the gum, this undergoes some peculiar
changes : its edge at first becomes dense and sharp, but, as the tooth ap-
proaches it, the sharp edge disappears, the gum becomes rounded or tumid,
and is of a purplish hue ; the summit of the tooth is seen like a white spot
or line through the vascular gum, and soon afterwards rises through it. As
the crown of the tooth advances to its ultimate position, the elongated fang
becomes surrounded by a bony socket or alveolus. Before the eruption, the
mucous membrane is studded with a number of small white bodies, which
were described by Serres as glands (dental glands), and were supposed by him
to secrete the tartar of the teeth. Meckel thought they were small abscesses,
because no aperture could be detected in them. In a fcetus of six months,
they were found by Sharpey to be small round pearl- like bodies situated hi
the corium of the mucous membrane, and having no aperture : they con-
sist of small spherical capsules of various sizes, lined with a thick stratum
of epithelium, the inner cells of which are flattened or scaly, like those lining
the cheek, and are so numerous as almost to fill up the cavity. They are
the prominences of the outer epithelial layer of the enamel organ, already
referred to.
Development of the permanent teeth. — The preceding description of the
structure of the dental sacs and pulps and of the mode of formation of the
DEVELOPMENT OF THE PERMANENT TEETH. 801
several parts of a tooth, applies to the permanent as well as to the milk-
teeth.
The origin and progressive development of the sacs of the permanent teeth
have still to be considered. There are six more permanent teeth in each jaw
than there are milk-teeth, and it is found that the sacs of the ten anterior
permanent teeth, which succeed the ten milk-teeth, have a different mode of
origin from the six additional or superadded teeth, which are formed further
back in the jaw.
Fig. 559. — ENLARGED DIAGRAM OP THE DENTAL Fig. 559.
ARCH ON THE LEFT SIDE ov THE LOWER JAW OF A
FCETUS OF ABOUT FOURTEEN WEEKS (slightly
altered from Goodsir).
/, the follicles of the five milk-teeth, supposed lo
be open, showing the dental papillae within them,
and o, the opercula on their borders ; they are
numbered from 1 to 5 in the order of their first ap-
pearance ; c, to the inside of each is the lunated
depression forming the commencement of the germ
of the corresponding permanent tooth ; a b, line of
the section shown in fig. 551, 5.
The sacs and pulps of the ten anterior per-
manent teeth have their foundations laid
before birth, behind those of the milk set.
Recurring to the follicular stage of the tem-
porary teeth, which is completed about the
fourteenth week, it will be remembered that behind each milk-follicle there is
formed a small lunated recess, similar in form to an impression made by the
nail. As already stated, the mucous membrane lining these recesses escapes
the general adhesion of the lips and sides of the dental groove, so that when
the latter closes they are converted into so many cavities, which are called
by Goodsir, " cavities of reserve." They are ten in number in each jaw,
and are formed successively from before backwards. They ultimately form
the sacs for the permanent incisor, canine, and bicuspid teeth. These cavi-
ties soon elongate and recede into the substance of the gum behind the milk
follicles, above and behind in the upper jaw, below and behind in the lower.
In the meantime, a papilla appears in the bottom of each, (that for the
central incisor appearing first, at about the sixth month,) and one or more
folds or opercula, as in the case of the temporary teeth, are developed from
the sides of the cavity, and, by their subsequent union, divide it into two
portions, the lower portion containing the papilla, and now forming the
dental sac and pulp of the permanent tooth, and the upper and narrower
portion being gradually obliterated in the same manner as the primitive
groove was closed over the milk-sacs. When these changes have taken
place, the permanent sac adheres to the back of that for the temporary
tooth. Both of them continue then to grow rapidly, and after a time it is
found that the bony socket not only forms a cell for the reception of the
milk-sac, but also a small posterior recess or niche for the permanent sac,
with which the recess keeps pace in its growth. Confining our description
now, for convenience, to the lower jaw only, it is found that at length the
permanent sac so far recedes in the bone as to be lodged in a special osseous
cavity at some distance below and behind the milk-tooth, the two being com-
pletely separated from each other by a bony partition. In descending into
3 u
802
THE TEETH.
the jaw, the permanent sac acquires at first a pear-shap.e, and is then con-
nected with the gum by a solid membranous pedicle. The recess in the jaw
has a similar form, drawn out into a long canal for the pedicle, which opens
Fig. 560.
II.
III.
IV.
V.
Fig. 560. — SKETCHES SHOWING THE RELATIONS OP THE TEMPORARY AND PERMANENT
DENTAL SACS AND TEETH (after Blake, with some additions).
The lower parts of the three first figures, which are somewhat enlarged, represent
sections of the lower jaw through the alveolus of a temporary incisor tooth : a, indicates
the sac of the permanent tooth ; c, its pedicle ; 6, the sac of the milk tooth or the milk
tooth itself ; a', b', indicate the alveolar recesses in which the permanent and temporary
teeth are lodged, and c, the canal by which that of the former leads to the surface of
the bone behind the alveolus of the temporary tooth. The fourth and fifth figures, which
are nearly of the natural size, show the same relations in a more advanced stage, in IV,
previous to the change of teeth, in V, when the milk-tooth has fallen out and tbe per-
manent tooth begins to rise in the jaw ; c, the orifice of the bony canal leading to the
place of the permanent tooth.
on the edge of the jaw, by an aperture behind the corresponding milk-tooth.
The permanent tooth is thus separated from the socket of the milk-tooth by
a bony partition, against which, as well as against the root of the milk-tooth
just above it, it presses in its rise through the gum, so that these parts are in
a greater or less extent absorbed. When this has proceeded far enough, the
milk-tooth becomes loosened, falls out or is removed, and the permanent
tooth takes its place. The absorption of the dental substance commences
at or near the ends of the fangs, and proceeds upwards until nothing but
the crown remains. The cement is first attacked, and then the dentine :
but the process is similar in the two tissues. The change is not produced
merely by pressure, but through the agency of a special cellular structure
developed at the time, and applied to the surface of the tooth. Hollows or
indentations occur upon the latter, giving it a festooned appearance : and it
frequently happens that the dental tissues are deposited, absorbed, and
redeposited alternately in the same tooth (Tomes). The milk-teeth and
the permanent teeth are said by Serres to be supplied by two different
arteries, the obliteration of the one belonging to the temporary teeth being
regarded by him as the cause of their destruction ; but of this there is no
sufficient proof.
The six posterior (or " supet added ") permanent teeth, that is, the three
permanent molars on each side, do not come in the place of other teeth.
They arise from successive extensions of the dental groove carried backwards
in the jaw, posterior to the milk-teeth, and named by Goodsir " posterior
cavities of reserve. "
DEVELOPMENT OF THE PERMANENT TEETH. 803
During the general adhesion of the dental groove occurring at the fifteenth
week, the part posterior to the last temporary molar follicle continues unob-
literated, and thus forms a cavity of reserve, in the fundus of which a
papilla ultimately appears, and forms the rudiment of the first permanent
molar tooth : this takes place very early, viz., at the sixteenth week. The
deepest part of this cavity is next converted by adhesion into a sac, which
encloses the papilla, whilst its upper portion elongates backwards so as to
form another cavity of reserve, in which, at the seventh month after birth,
the papilla for the second molar tooth appears. After a long interval, during
which the sac of the first permanent molar and its contained tooth have
acquired great size, and that of the second molar has also advanced con-
siderably in development, the same changes once more occur, and give rise to
the sac and papilla of the wisdom tooth, the rudiments of which are visible
at the sixth year. The subsequent development of the permanent molar
teeth takes place from these sacs just like that of the other teeth.
Calcification begins first in the anterior permanent molar teeth. Its order
and periods may be thus stated for the upper jaw, the lower being a little
earlier : First molar, five or six months after birth ; central incisor, a little
later ; lateral incisor and canine, eight or nine months ; two bicuspids, two
years or more ; second molar, five or six years ; third molar, or wisdom
tooth, about twelve years.
Fig. 561.
Fig. 561.— PART OP THE LOWER JAW OF A CHILD OP THREE OR FOUR YEARS OLD,
SHOWING THE RELATIONS OP THE TEMPORARY AND PERMANENT TEETH.
The specimen contains all the milk-teeth of the right side, together with the incisors of
the left; the inner plate of the jaw has been removed, so as to expose the sacs of all the
permanent teeth of the right side, except the eighth or wisdom tooth, which is not yet
formed. The lai'ge sac near the ramus of the jaw is that of the first permanent molar,
and above and behind it is the commencing rudiment of the second molar.
Eruption of the permanent teeth. — The time at which this occurs in regard
to each pair of teeth in the lower jaw is exhibited in the subjoined table.
The corresponding teeth of the upper jaw appear somewhat later.
Molar, first 6 years.
Incisors, central . . . . . . . . 7 „
„ lateral ........ 8 „
Bicuspids, anterior 9 „
,, posterior . , . . . . 10 „
Canines 11 to 12 „
Molars, second . . . . . . 12 to 13 „
„ third (or wisdom) . . . . 17 to 25 „
3 G 2
804
THE TEETH.
It is just before the shedding of the temporary incisors, i. e. , about the
sixth year, that there is the greatest number of teeth in the jaws. At that
period there are all the milk-teeth, and all the permanent set except the
wisdom teeth, making forty-eight.
Fig. 562.
Fig. 562.— THE TEETH OP A CHILD OP Six YEARS, WITH THE CALCIFIED PARTS OP THE
PERMANENT TEETH EXPOSED (after Henle aud from nature).
The whole of the teeth of the right side are shown, together with the three front teeth
of the left side : in the upper and lower jaws the teeth are indicated as follows, viz. : —
1, milk-teeth — i, inner or first incisor ; i', outer or second incisor ; c, canine ; m, first
molar ; m! second molar. 2, permanent teeth— I, inner or first incisor ; 1', outer or
second incisor; C, canine; B, first bicuspid; B' second bicuspid; M1, the first molar,
which has passed through the gums ; M2, the second molar, which has not yet risen above
the gums : the third molar is not yet formed.
During the growth of the teeth the jaw increases in depth and length,
and undergoes changes in form. In the child it is shallow, but it becomes
much deeper in the adult. In the young subject the alveolar arch describes
almost the segment of a circle ; but in the adult the curve is semi-elliptical.
The increase which takes place in the length of the jaw arises from a growth
behind the position of the milk-teeth, so as to provide room for the three
additional teeth on each side belonging to the permanent set. At certain
periods in the growth of the jaws there is not sufficient room in the alveolar
arch for the growing sacs of the permanent molars ; and hence those parts
are found at certain stages of their development to be enclosed in the base
of the coronoid process of the lower jaw, and in the maxillary tuberosity in
the upper jaw, but they afterwards successively assume their ultimate
position as the bone increases in length. The space taken up by the ten
THE TONGUE 805
anterior permanent teeth very nearly corresponds with that which had been
occupied by the ten milk-teeth ; the difference in width between the incisors
of the two sets being compensated for by the smallness of the bicuspids in
comparison with the milk-molars to which they succeed. Lastly, the angle
formed by the rarnus and body of the lower jaw differs at different ages ;
thus it is obtuse in the infant, approaches nearer to a right angle in the
adult, and again becomes somewhat obtuse in old age. (See p. 52.)
Relation of the blood-vessels and nerves to the tooth. — There is no evidence that the
blood-vessels send branches into the hard substance. The red stain sometimes
observed in the teeth, after death by asphyxia, and the red spots occasionally found
in the dentine, are due to the imbibition of blood effused on the surface of the pulp.
The dentine formed in young animals fed upon madder is tinged with that colouring
matter, but this does not appear to take place when the growth of the tooth is com-
pleted. Nevertheless the tubules of the dentine may serve to convey through its
substance nutrient fluid poured out by the blood-vessels of the pulp. The teeth are
sometimes stained yellow in jaundice.
According to Czermak the primitive nerve-tubules run into the tooth -pulp in
bundles, which are large towards the centre, and small at the periphery. They lose
themselves in a plexus at the surface of the pulp. Czermak states that the fibres often
divide, but that he has not seen loops frequently, and he is doubtful as to the precise
mode of their termination,
THE TONGUE.
The tongue is a muscular organ covered with mucous membrane. By its
muscular structure it takes part in the processes of mastication and deglu-
tition, and in the articulation of speech, while its mucous membrane is
endowed with common sensibility and is the seat of the sense of taste. The
tongue occupies the concavity of the arch of the lower jaw : posteriorly it is
connected with the hyoid bone, and the back part of its dorsum forms the
floor of the arch of the fauces ; inferiorly it receives from base to apex the
fibres of the genio-glossus muscle, and through the medium of that muscle is
attached to the lower jaw.
A. — Mucous MEMBRANE. — On the under surface of the tongue the mucous
membrane is smooth and thin. It forms a fold in the middle line, called
the frcenum lingua, placed in front of the anterior border of the genio-glossi
muscles. On each side below, as the mucous membrane passes from the
tongue to the inner surface of the gums, it is reflected over the sublingual
gland. Not far from the line continued forwards from the frsenum, the
ranine vein may be distinctly seen through the mucous membrane, and close
to it lies the ranine artery. Further outwards is an elevated line with a
fimbriated margin directed outwards, which extends to the tip. The ducts
of the right and left submaxillary glands end by papillary orifices placed
close together, one on each side of the freenum ; and further back, in the
groove between the sides of the tongue and the lower jaw, are found the
orifices of the several ducts belonging to the sublingual glands.
The upper surface or dorsum of the tongue is convex in its general out-
line, and is marked along the middle in its whole length by a slight farrow
called the raphe, which indicates its bilateral symmetry. About half an
inch from the base of the tongue, the raphe often terminates in a depres-
sion, closed at the bottom, which is called the foramen ccecum (Morgagui),
and in which several mucous glands and follicles open. Three folds, named
the glosso-epiglottic folds or frseuula, of which the middle one is the largest
(frsenum epiglottidis), pass backwards from the base of the tongue to the
epiglottis. The upper surface of the tongue is completely covered with
806
THE TONGUE.
numerous projections or eminences named papillce. They are founl also
upon the tip and free borders, where, however, they gradually become
smaller, and disappear towards its under surface. These papillae are dis-
tinguished into three orders, varying both in size and form.
Fig. 563.
Fig. 563. —PAPILLAE SURFACE OF THE TONGUE, WITH THE FAUCES AND TONSILS (from
Sappey).
1, 2, circumvallate papillae ; in front of 2, the foramen caecum ; 3, fungiform papillae ;
4, filiform and conical papillae ; 5, transverse and oblique rugae ; 6, mucous glands at
the base of the tongue and in the fauces ; 7, tonsils ; 8, part of the epiglottis ; 9, median
glosso-epiglottidean fold or fraenum epiglottidis,
The large or circumvallate papillae, from seven to twelve in number, are
found on the back part of the tougue, arranged in two rows, which run
obliquely backwards and inwards, and meet towards the foramen caecum, like
the arms of the letter V. They are situated in cup-like cavities or depres-
sions of the mucous membrane, and have the shape of an inverted cone, of
which the apex is attached to the bottom of the cavity, and the broad
flattened base appears on the surface. They are therefore surrounded by a
PAPILLA OF THE TONGUE.
807
circular furrow or trench, around which again is an annular elevation of the
mucous membrane, covered with the smaller papillae. The exposed surface
of the papillae vallatse is beset with numerous smaller papillae or filaments ;
Fig. 564.
Fig. 564.— VERTICAL SECTION
OF THE ClRCUMVALLATE
PAPILLAE (from Kolliker). ^
A, the papilla ; B, the sur-
rounding wall; a, the epi-
thelial covering ; b, the nerves
of the papilla and wall spread-
ing towards the surface ; c,
the secondary papillae.
and in some of them there
is found a central depres-
sion, into which mucous follicles open.
The middle-sized or fungiform papillse, more numerous than the last, are
small rounded eminences scattered over the middle and fore part of the
dorsum of the tongue ; but they are found in great numbers and closer
Fig. 565.
Fig. 565. — SURFACE AND SECTION OF THE FUNGI-
FORM PAPILLA (from Kolliker after Todd and
Bowman).
A, the surface of a fungiform papilla partially
denuded of its epithelium, ^ ; p, secondary
papillse ; e, epithelium.
B, section of a fungiform papilla with the
blood-vessels injected, a, artery ; v, vein ; c,
capillary loops of simple papillaa in the neigh-
bouring structure of the tongue ; d, capillary
loops of the secondary papilla? ; e, epithelium.,
together at the apex and upon the bor-
ders. They are easily distinguished in
the living tongue by their deeper red
colour. They are narrow at their point
of attachment, but are gradually enlarged
towards their free extremities, which are
blunt and rounded, and are covered with
smaller filamentous appendages or papillae.
The smallest papilhe, conical and fili-
form, are the most numerous of all. They
are minute, conical, tapering, or cylin-
drical processes, which are densely packed
over the greater part of the dorsum of the
tongue, but towards the base gradually
disappear. They are arranged in lines, which correspond at first with the
oblique direction of the two ridges of the papillae vallatae, frit gradually be-
come transverse towards the tip of the tongue. At the sides they are longer
and more filiform, and arranged in parallel rows, perpendicular to the border
of the tongue.
Considerable variety occurs in the appearance of the papillze on the tongues ot
different persons. Thus occasionally instances occur in which the tongue has a
quite smooth appearance, and others are seen in which numbers of the filiform papillae
are elongated into the appearance of short brown hairs, as shown in Fig. 566.
808
THE TONGUE,
When examined microscopically in sections, all the kinds of papillee now
described are observed to be bearers of closely set secondary papillae. The
secondary papillae are the structures which correspond with the papillae of
the general integument, and are occupied each by a long loop of capillary
blood-vessel. Simple papillae of the same description are likewise inter-
spersed between the three large kinds, and are found on the back part of
Fig. 566. — Two FILIFORM PAPILLAE,
ONE WITH EPITHELIUM, THE OTHER
WITHOUT (from Kolliker, after
Todd and Bowman). ^
p, the substance of the papillae di-
viding at their upper extremities into
secondary papillae ; a, artery, and v,
vein, dividing into capillary loops ;
e, epithelial covering, laminated be-
tween the papillae, but extended into
hair-like processes /, from the ex-
tremities of the secondary papillae.
the tongue, behind the circum-
vallate range, as well as covering
the under surface of the tongue
and the rest of the mucous mem-
brane of the mouth. The epi-
thelium covering the tongue,
like that of the mouth generally,
is of the squamous kind. It is
of considerable thickness, and
the simple papillae, together with
the secondary papillae surmount-
ing those of the circumvallate
and fungiform kinds, are con-
cealed beneath it, or nearly so.
But the secondary papillae, borne
by those of the filiform kind,
are peculiar both in contain-
ing a number of elastic fibres,
which give them greater firmness, and in the character of their epithelial
covering, which is dense and imbricated, and which forms a separate process
over each, greater in length than the papilla which it covers. Over some
of the filiform papilla these processes form a pencil of fine fibres ; and on
others they approach closely in character and structure to hairs. The papillae
are undoubtedly the parts chiefly concerned in the special sense of taste ;
but they also possess, in a very acute degree, common tactile sensibility ;
and the filiform papillae, armed with their denser epithelial covering, serve
a mechanical use, in the action of the tongue upon the food, as is well
illustrated by the more developed form which these papillae attain in many
carnivorous animals. The papillary surface of the tongue is supplied abun-
dantly with nerves. It is difficult to trace the nerve- fibres in the papillae
filiformes, owing to the presence of elastic filaments. In the papillae fungi-
formes the nerves are larger and more numerous, and form a plexus with
brush- like branches : but they are still more abundant, and of greater size
in the papillae circumvallatae.
Little that is satisfactory is known of the mode of termination of the
LINGUAL PAPILLA AND GLANDS.
809
nerve filaments in the human tongue. It is still a matter of doubt whether
they enter the secondary papillae surmounting the filiform set, the density of
the tissue rendering the investigation peculiarly difficult in these. In
the frog's tongue, Billroth and Axel Key believe that they have traced con-
tinuity of nerve- filaments with structures in the epithelium ; and, according
to Axel Key, the arrangement is very similar to that of the olfactory cells
— viz., rodHke bodies placed between the epithelial cells and continuous by
their deep extremities with varicose fibres. (Billroth in Muller's Archiv,
1858, p. 159 ; Axel Key in Reichert's Archiv, 1861, p. 329).
Glands. — The mucous mem-
brane of the tongue is provided
with numerous follicles and
glands. The follicles, simple and
compound, are scattered over the
surface ; but the rounded con-
glomerate glands, called lingual
glands, are collected about the
posterior part of the dorsum of
Fig. 567. — RACEMOSE Mucous GLAND,
FROM THE FLOOR OF THE MoDTH
(from Kolliker).
A, the entire gland as seen in sec-
tion ; 4p a, covering of connective
tissue ; 6, excretory duct; c, glandular
vesicles ; d, duct of one of the lo-
bules.
B, diagram of one of the lobules,
more highly magnified; a, excretory
duct of the lobule ; b, secondary
branch ; c, the glandular vesicles as
they lie together in the gland ; d, the
same separated, showing their con-
nection as a glandular tube.
the tongue, near the B
papillae vallatse and
foramen csecum, into
which last the ducts
of several of these
glands open, Other
small glands are
found also beneath
the mucous mem-
brane of the borders
of the tongue.
There is, in particular, a small group of these glands on the under surface
of the tongue near the apex. They are there aggregated into a small oblong
mass, out of which several ducts proceed and open separately on the mucous
membrane. (Blandin, in Archives gen. de Me'decine, 1823 ; Nuhn, Ueber
eilie noch nicht naher beschriebene Zungendriise, Mannheim, 1845.)
B. — MUSCULAR SUBSTANCE. — The substance of the tongue is chiefly com-
posed of muscular fibres, running in different but determinate directions ; —
hence the variety and regularity of its movements, and its numerous changes
of form. Many of the contractile fibres of the tongue belong to muscles
810 THE TOXGUE.
which enter at its base and under surface, and attach it to other paits :
these are called the extrinsic muscles of the tongue, and have been elsewhere
described (pp. 185 — 186). Other bands of fibres which constitute the
intrinsic or proper muscles, and are placed entirely within the substance of
the organ, will be here more particularly noticed. They are as follow.
The lingualis superficialis (noto-glossus, Zaglas), consisting mainly of longi-
tudinal fibres, is placed on the upper surface of the tongue, immediately
beneath the mucous membrane, and is traceable from the apex of the organ
backwards to the hyoid bone. The individual fibres do not run the whole
of this distance, but are attached at intervals to the submucous and glandular
tissues. The entire layer becomes thinner towards the base of the tongue,
near which it is overlapped at the sides by a thin plane of oblique or nearly
transverse fibres derived from the palato-glossus and hyo-glossus muscles.
According to Zaglas, the fibres of this muscle are directed forwards and out-
wards.
The lingualis inferior (lingualis muccle of Douglas, Albinus, <fec.) consists
of a rounded muscular baud, extending along the under surface of the
tongue from base to apex, and lying outside the genio-hyo-glossus between
that muscle and the hyo-glossus. Posteriorly, some of its fibres are lost in
the substance of the tongue, and others reach the hyoid bone. In front,
Fig. 568. — LONGITUDINAL VERTICAL SECTION OF THE TONGUE, LIP, &c. (from Kolliker
and Arnold).
m, symphysis of the lower jaw; tZ, incisor tooth ; h, hyoid bone ; g h, genio-hyoid
muscle; g, genio-hyo-glossus spreading into the whole extent of the tongue ; t r, trans-
verse muscle : Is, superior longitudinal muscle ; gl, lingual glands ; f, lingual follicles; c,
epiglottis ; I, section of the lip and labial glands ; o, cut fibres of the orbicularis oris ;
I m, levator menti.
having first been joined, at the anterior border of the hyo-glossus muscle,
by fibres from the stylo-glossus, it is prolonged beneath the border of the
tongue as far as its point.
The transverse muscular fibres of the tongue form together with" the inter-
mixed fat a considerable part of its substance. They are found in the in-
INTRINSIC MUSCLES OF THE TONGUE. 811
terval between the upper and lower longitudinal muscles, and they are inter-
woven extensively with the other muscular fibres. Passing outwards from the
median plane, where they take origin from a fibrous septum, they reach the
dorsum and borders of the tongue. In proceeding outwards, they separate,
and the superior fibres incline upwards, forming a series of curves with the
concavity turned upwards. The fibres of the palato-glossus muscle are found
by Zaglas and Henle to be continuous with fibres of the transverse set.
Fig. 569. — TRANSVERSE Fig. 569.
VERTICAL SECTION OF THE
TONGUE IN FRONT OF THE
PAPILLA VALLAT.E, SEEN
FROM BEFORE (from
Kolliker).
g, the genio-hyo-glossi
muscles ; </, the vertical
fibres of the right side traced
upwards to the surface ; lit
inferior longitudinal muscle
•with the divided ranine ar-
tery ; tr, transverse muscle,
entire on one side, but par-
tially removed on the other,
where the other muscles pass
through it; c, septum lin-
guae ; h, hyo-glossus ; h g I,
its fibres spreading upwards
almost vertically outside the
genio-hyo-glossus ; k', vertical fibres reaching the surface ; Is, divided plates of the fibres
of the superior longitudinal muscle between the vertical fibres ; s t, g I, stylo-glossus ; d,
glands near the border of the tongue.
Vertical fibres (musculus perpendicularis externus of Zaglas), decussating
with the transverse fibres and the insertions of the genio-glossus, form a set
of curves in each half of the tongue with their concavity upwards, and ex-
tending downwards and outwards from the dorsum to the under surface of
the border, so that those which are outermost are shortest. (Zaglas, " On
the Muscular Structure of the Tongue," in Goodsir's Annals, I. p. 1.)
Examined in transverse sections, the muscular fibres of the tongue are seen
to be arranged so as to render the substance divisible into an outer part or
cortex and a softer internal medulla. The fibres of the cortex are principally
longitudinal, derived superiorly from the lingualis superior, further outwards
from the hyo-glossus, on the side from the stylo-glossus, and beneath this
from the lingualis inferior. They sheath the medullary part on all sides
except inferiorly, where the genio-glossi muscles enter it between the infe-
rior linguales. In the medullary part are found, imbedded in fat, the de-
cussating fibres of the transverse muscle passing across, the genio-glossi
radiating upwards and outwards, and the vertical muscles arching down-
wards and outwards. In addition to the movements which may be given
to the tongue -by the extrinsic muscles, this organ is capable of being curved
upwards, downwards, or laterally by its cortical fibres, it is flattened by the
vertical fibres, and its margins are again drawn together by the transverse.
The septum of the tongue is a thin fibrous partition which extends forwards
from the hyoid bone to the tip, and divides one half of the medullary part of
the tongue from the other, but does not penetrate into the cortex. It cor-
responds with the fusiform fibro-cartilage, found in the middle of the tongue
of the dog, near its under surface.
812
THE TONGUE.
The arteries of the tongue are derived from the lingualis, with some small branches
from the facial and ascending pharyngeal. With these the veins for the most part
correspond. (See pp. 348 and 456.)
Fig. 570.
Fig. 570. — LATERAL VIEW OF THE NERVES AND BLOOD-VESSELS OP THE TONGUE (from
Hirschfeld and Leveille). f
The lower jaw has been divided near the syraphysis, and the right half removed ; the
hyoid bone is entire, and the extrinsic muscles of the tongue are preserved on the right
side, a, the epithelial covering of the tongue partially raised ; 6, the papillar surface of
the mucous membrane exposed ; c, the same near the papillae vallatse ; d, placed on the
superior constrictor of the pharynx, points to the stylo-glossus muscle ; e, stylo-pharyngeus
muscle, passing within the middle constrictor ; /, hyo-glossus ; g, middle constrictor of
the pharynx ; h, genio-hyo-glossus ; i, genio-hyoideus ; 1, trunk of the lingual artery ; 2,
ranine artery ; 3, sublingual branch ; 4, its terminal branches ; 5, trunk of the gustatory
nerve ; 5', distribution of its terminal twigs in the mucous membrane of the fore part of
the tongue ; 5", submaxillary ganglion ; 5"', another small ganglion, connected with the
gustatory nerve ; 6, chorda tympani nerve, passing from the facial nerve 7, to the trunk
of the gustatory ; 8, trunk of the glosso-pharyngeal, receiving a twig of communication
from the facial ; 8', its distribution near the papillae vallatse ; 9, hypoglossal nerve ; 9',
its twigs to the hyo-glossus muscle and union with the gustatory ; further forward are
seen its terminal branches to the muscular su bstance of the tongue.
The nerves of the tongue (exclusive of branches from the sympathetic nerves) are
three : viz. the lingual or gustatory branch of the ffth pair, which supplies the
papillae and mucous membrane of the fore part and sides of the tongue to the extent
of about two- thirds of its surface ; the lingual branch of the glosso-pharyngeal, which
sends filaments to the mucous membrane at the base of the tongue, and especially to
the papillae vallatae ; and, lastly, the Uypoglossal nerve, which is distributed to the
muscles. (See the description of these nerves.) Remak and Kolliker have dis-
covered microscopic ganglia upon the expansion of the glosso-pharyngeal nerve, and
in the sheep and calf upon the gustatory division of the fifth. Remak thought that
they had some relation to the glands, but Kolliker finds them on branches not con-
nected with those organs.
THE PALATE.— THE TONSILS. 813
THE PALATE.
The roof of the mouth is formed by the palate, which consists of two por-
tions ; the fore part being named the hard palate, and the back part, the
soft palate.
The osseous framework of the hard palate, already described with the
bones of the faco, is covered by the periosteum, and by the lining membrane
of the mouth, which adhere intimately together. The mucous membrane,
which is continuous with that of the gums, is thick, dense, rather pale, and
much corrugated, especially in front aud at the sides ; but is smoother,
thinner, and of a deeper colour behind. Along the middle line is a ridge or
raphe, ending in front in a small eminence, which corresponds with the lower
opening of the anterior palatine canal, and receives the terminal filaments of
the naso-palatine and anterior palatine nerves. The membrane of the hard
palate is provided with many muciparous glands, which form a continuous
layer between the membrane and the bone, and it is covered with a squamous
epithelium.
The soft palate (velum pendulum palati), is formed of a doubling of mucous
membrane inclosing muscular fibres and numerous glands. It constitutes an
incomplete and moveable partition between the mouth aud the pharynx, con-
tinued from the posterior border of the hard palate, obliquely downwards and
backwards. Its form and its inferior connections, bounding the isthmus of
the fauces, have been already described, together with the muscles which
enter into its composition, at p. 189.
The anterior or under surface of the velum, which is visible in the mouth,
is concave. The mucous membrane, continuous with that of the hard palate,
is thinner and darker than it, and is covered like it with scaly epithelium.
The median ridge or raphe, which is continued backwards from the hard
palate to the base of the uvula, indicates the original separation of the velum
into two lateral halves.
The posterior surface of the soft palate, slightly convex or arched, is con-
tinuous above with the floor of the posterior nares. It is slightly elevated
along the middle line, opposite to the uvula. The greater portion of its
mucous membrane, as well as that of the free margin of the velum, is covered
with a squamous epithelium ; but quite at its upper portion, near the orifice
of the Eustachian tube, the epithelium is columnar and ciliated.
On both surfaces of the velum are found numerous small glands, called
the palatine glands. They particularly abound on the upper surface, where
they form quite a glandular layer ; they are also very abundant in the
uvula.
THE TONSILS.
The tonsils (tonsillse, amygdalae) are two prominent bodies, which occupy
the recesses formed, one on each side of the fauces, between the anterior and
posterior palatine arches and the pillars of the fauces.
They are usually about six lines in length, and four in width and thick-
ness ; but they vary much in size in different individuals.
The outer side of the tonsil is connected with the inner surface of the
superior constrictor of the pharynx, and approaches very near to the internal
carotid artery. Considered in relation to the surface of the neck, the tonsil
corresponds to the angle of the lower jaw, where it may be felt beneath the
skin when it is enlarged. Its inner surface, projecting into the fauces
814
THE TONSILS.
between the palatine arches, presents from twelve to fifteen orifices, which
give it a perforated appearance. These orifices lead into recesses in the
substance of the tonsil, from which other and smaller orifices conduct still
Fig. 571. Fig. 571.— SECTION OP A FOL-
LICULAR GLAND FROM THE
ROOT OP THE TONGUE (from
Kolliker). M
a, epithelial lining ; 6, papil-
lae of the mucous membrane ; c,
outer surface of the capsule,
formed of connective tissue : d,
outlet, and e, cavity of the cap-
sule ; g, follicles in the substance
of the capsular wall.
deeper into numerous fol-
licles. These follicles are
lined by the epithelium and
papillary mucous membrane of the throat, and have thick walls formed
by a layer of closed capsules imbedded in the submucoua tissue. The cap-
sules, which may be compared to those of Peyer's glands of the intestine,
besides having a mesh-work of capillary blood-vessels and delicate trabecular
tissue within them, are filled with consistent greyish substance, containing
cells and free nuclei, but without the characters of mucus. A substance having
the same microscopic elements is found in the cavity of the follicle, but
here it is liable to be mixed with mucus supplied by true mucous glands,
the ducts of which pass into the follicle. The function of the tonsils is as
little known as that of the other glands formed of closed capsules which
are found in the mucous membrane of the alimentary canal.
FollicuJar recesses, surrounded by closed capsules, like the recesses and
capsules of the tonsils, are also found at the root of the tongue, where they
form a layer extending from the papillae vallatse to the epiglottis, and from
one tonsil to the other, lying immediately beneath the mucous membrane
and above the mucous glands, many of whose ducts they receive.
The tonsils receive a very large supply of blood from various sources, viz. from the
tonsillar and palatine branches of the facial artery, and. from the descending palatine,
the ascending pharyngeal and the dorsalis linguae. From these arteries, fine branches
and capillaries are distributed abundantly to the walls of the capsules and to the
papillae of the mucous membrane lining the follicles. The veins are numerous, and
enter the tonsillar plexus on its outer side. The nerves come from the glosso-
pharyngeal nerve, and from the fifth pair.
THE SALIVARY GLANDS.
The saliva, which is poured into the mouth, and there mixed with the
food during mastication, is secreted by three pairs of glands, named from
their respective situations, parotid, submaxillary, and sublingual. Agreeing
in their general physical characters and minute structure, these glands difier
in their size, form, and position.
The Parotid Gland.
The parotid is the largest of the three salivary glands. It lies on the side
of the face, in front of the ear, and extends deeply into the space behind
the ramus of the lower jaw. Its weight varies from five to eight drachms.
THE PAROTID GLAND.
815
Its outer surface is convex and lobulated, and is covered by the skin and
fascia, and partially by the platysma muscle. It is bounded above by the
zygoma, below by a line drawn backwards from the lower border of the jaw
to the sterno-mastoid muscle, and behind by the external meatus of the ear,
the mastoid process, and sterno-mastoid muscle. Its anterior border, which
lies over the ramus of the lower jaw, is less distinctly defined, and stretches
forwards to a variable extent on the masseter muscle. It is from this
anterior border of the gland that the excretory duct passes off ; and there is
Fig. 572.
Fig. 572. — SKETCH OF A SUPERFICIAL DISSECTION OP THE FACE, SHOWING THE POSITION
OF THE PAROTID AND SDBMAXILLARY GLANDS, f
p, the larger part of the parotid gland ; p", the small part, which lies alongside the duct
on the masseter muscle ; d, the duct of Stenson before it perforates the buccinator
muscle ; a, transverse facial artery ; n, n, branches of the facial nerve emerging from
below the gland ; f, the facial artery passing out of a groove in the submaxillary gland
and ascending on the face ; s m, superficial larger portion of the submaxillary gland lying
over the posterior part of the mylo-hyoid muscle.
frequently found in connection with the duct, and lying upon the masseter
muscle, a small process or a separated portion of the gland, which is called
glandula soda (soda parotidis). On trying to raise the deeper part of the
parotid gland from its position, it is found to extend far inwards, between
the mastoid process and the ramus of the jaw, towards the base of the skull,
and to be intimately connected with several deep-seated parts. Thus, above,
it reaches into and occupies the posterior part of the glenoid cavity ; behind
and below, it touches the digastric muscle, and rests on the styloid process
816 THE SALIVARY GLANDS.
and styloid muscles ; and, in front, under cover of the ramus of the jaw, it
advances a certain distance between the external and internal pterygoid
muscles.
The internal carotid artery and internal jugular vein are close to the deep
surface of the gland. The external carotid artery, accompanied by the tem-
poral and internal maxillary veins, passes through the parotid gland ; and in
that situation arise the temporal and internal maxillary arteries, as also the
auricular and transverse facial branches of the temporal. The gland is also
traversed by the facial nerve, which divides into branches within its sub-
stance, and it is pierced by branches of the great auricular nerve.
The parotid duct, named also Stenson's duct (d. Stenonianus), appears at
the anterior border of the gland, about one finger's breadth below the zygoma,
and runs forwards over the masseter muscle, accompanied by the socia paro-
tidis, when that accessory portion of the gland exists, and receiving its ducts.
At the anterior border of the masseter, the duct turns inwards through the
fat of the cheek and pierces the buccinator muscle ; and then, after running
for a short distance obliquely forwards beneath the mucous membrane, opens
upon the inner surface of the cheek, by a small orifice opposite the crown of
the second molar tooth of the upper jaw. Its direction across the face may
be indicated by a line drawn from the lower margin of the concha of the ear
to a point midway between the red margin of the lip and the ala of the nose.
The length of the Stenonian duct is about two inches and a half, and its
thickness about one line and a half. At the place where it perforates the
buccinator, its canal is as large as a crow-quill, but at its orifice it is smaller
than in any other part, and will only admit a very fine probe. The duct is
surrounded by areolar tissue, and consists of an external, dense, and thick
fibrous coat, in which contractile fibres are described, and of an internal
mucous tunic, which is continuous with that of the mouth, but which is
covered, from the orifice of the duct as far as to the smallest branches, with
a columnar epithelium.
The parotid gland belongs to the class of compound racemose glands, and
consists of numerous flattened lobes, held together by the ducts and vessels,
and by a dense areolar web, which is continuous with the fascia upon its outer
surface ; but the gland has no special or proper coat. The lobes are again
divided into lobules, each of which consist of the branched terminations of
the duct, and of vessels, nerves, and fine areolar tissue. The ducts termi-
nate in closed vesicular extremities, about ^^th of an inch or more in
diameter, which are lined with epithelium, and have capillary vessels
ramifying upon them.
The vessels of the parotid gland enter and leave it at numerous points. The arteries
are derived directly from the external carotid, and from those of its branches which
pass through or near the gland. The veins correspond. The absorbents join the deep
and superficial set in the neck ; and there are often one or more lymphatic glands
imbedded in the substance of the parotid. The nerves come from the sympathetic
(carotid plexus), and also, it is said, from the facial and the superficial temporal and
great auricular nerves.
An instance is recorded by Gruber of a remarkable displacement of the parotid on
one side ; the whole gland being situated on the masseter muscle as if it were an
enlarged socia parotidis. (Virchow's Archiv, xxxii., p. 328.)
The Submaxillary Gland.
The submaxillary gland, the next in size to the parotid gland, is of a
spheroidal form, and weighs about 2 or 2|- drachms. It is situated imme-
THE STJBLIXGUAL GLAND.
817
diately below the base and the inner surface of the inferior maxilla, and
above the digastric muscle. In this position it is covered by the skin and
the platysma myoides, and its inner surface rests on the mylo-hyoid, hyo-
glossus, and stylo-glossus muscles ; above, it corresponds with a depression
on the inner surface of the jaw-bone ; and it is separated behind from the
parotid gland merely by the stylo-maxillary membrane. The facial artery,
before it mounts over the jaw-bone, lies in a deep groove upon the back
part and upper border of the gland.
The duct of the submaxillary gland, named TVTiarton's duct, which is
about two inches in length, passes off from the gland, together with a thin
process of the glandular substance, round the posterior border of the mylo-
hyoid muscle, and then runs forwards and inwards above that muscle,
between it and the hyo-glossus and genio hyo-glossus, and beneath the
sublingual gland, to reach the side of the frsenum linguae. Here it ter-
minates, close to the duct of the opposite side, by a narrow orifice, which
opens at the summit of a soft papilla seen beneath the tongue. The
structure of this gland is like that of the parotid ; but its lobes are larger,
its surrounding areolar web is finer, and its attachments are not so firm.
Moreover, its duct has much thinner coats than the parotid duct.
The blood-vessels of the submaxillary gland are branches of the facial and lingual
arteries and veins. The nerves include those derived from the small submaxillary
ganglion, as well as branches from the mylo-hyoid division of the inferior dental
nerve, and the sympathetic.
The Sublingual Gland.
The sublingual gland, the smallest of the salivary glands, is of a narrow
oblong shape and weighs scarcely one drachm. It is situated along the
Fig. 573. — VIEW OP THE EIGHT SUB- Fig. 573.
MAXILLARY AND SlJBLINGUAL GLANDS
FROM THE INSIDE.
A part of the right side of the jaw,
divided from the left at the syinphysis,
remains ; the tongue and its muscles
have been removed ; but the mucous
membrane of the right side is retained
and is drawn upwards so as to expose
the sublingual glands ; s m, the larger
superficial part of the submaxillary
gland ; ft the facial artery passing
through it ; s m', deep portion pro-
longed within the mylo-hyoid muscle
m h ; s I, is placed below the anterior
large part of the sublingual glands, with
the duct of Bartholin partly shown ;
s I', placed above the hinder small end of the chain of glands, indicates the ducts of one
or two perforating the mucous membrane ; d, the papilla, at which the duct of Wharton
opens in front behind the incisor teeth; d't the commencement of the duct ; h, the hyoid
bone ; n, the gustatory nerve.
floor of the mouth, where it forms a ridge between the tongue and the
gums of the lower jaw, covered only by the mucous membrane. It reaches
from the frsenum linguae, in front, where it is in contact with the gland of
the opposite side, obliquely backwards and outwards for rather more than
an inch and a half. On its inner side it rests on the genio-hyo-glossus ;
beneath, it is supported by the mylo-hyoid muscle, which is interposed
3 H
818
THE SALIVARY GLANDS.
between it and the submaxillary gland ; but it is here in close contact
with the Whartonian duct, with the accompanying deep portion of the
last-named gland, and also with the lingual nerve.
The lobules of the sublingual gland are not so closely united together
as those of the other salivary glands, and the ducts from many of them
open separately into the mouth, along the ridge which indicates the posi-
Fig. 574.
B.
Fig. 574. — SKETCHES ILLUSTRATING THE FORMATION OF THE PAROTID GLAND (from
J. Muller).
A, head of a foetal sheep magnified, showing the early simple condition of the parotid
gland with the duct injected.
B, parotid gland of a foetal sheep more advanced, the ducts and blood-vessels injected.
tion of the gland. These ducts, named ducts of Jtivitii, are from eight to
twenty in number. Some of them open into the duct of Wharton. One,
longer than the rest (which is occasionally derived in part also from the
submaxillary gland), runs along the Whartonian duct, and opens either
with it or very near it ; this has been named the duct of Bartholin.
The blood-vessels of this gland are supplied by the sublingual and submental
arteries and veins. The nerves are numerous, and are derived from the lingual
branch of the fifth pair.
Saliva. — The saliva is a clear limpid fluid, containing a few microscopic
granular corpuscles. Its specific gravity is from 1 '006 to 1 '008, and it has
only from 1 to 1-| parts of solid matter in 100. The saliva is always alkaline
during the act of mastication ; but the fluid of the mouth becomes acid, and
remains so until the next time of taking food : the reason being that the
secretion of the mucous follicles of the mouth is acid, while that of the
salivary glands is alkaline. Its chief ingredients, besides water and mucus,
are a peculiar animal extractive substance, named salivine, with some
alkaline and earthy salts. It is remarkable, besides, for containing a minute
proportion of sulphocyanide of potassium.
THE PHARYNX. 819
Development. — In mammalia, according to Miiller and Weber, the salivary glands,
as shown in the case of the parotid gland in the embryo of the sheep, first appear in
the form of a simple canal with bud-like processes lying in a blastema, and communi-
cating with the cavity of the mouth. This canal becomes more and more ramified to
form the ducts, whilst the blastema soon acquires a lobulated form, corresponding with
that of the future gland, and at last wholly disappears, leaving the branched ducts,
with their blood-vessels and connecting tissues. The submaxillary gland is said to
be the first formed ; then the sublingual and the parotid.
THE PHARYNX.
The pharynx is that part of the alimentary canal which unites the cavi-
ties of the mouth and nose to the oesophagus. It extends from the base
of the skull to the lower border of the cricoid cartilage, and forms a sac
open at the lower end, and imperfect in front, where it presents apertures
leading into the nose, mouth and larynx.
The velum pendulum palati projects backwards into the pharynx, and
during the passage of the food completely separates an upper from a lower
part by means of the contraction of the muscles connected with it which are
placed in the posterior pillars of the fauces. Seven openings lead into the
cavity of the pharynx ; viz., above the velum, the two posterior openings
of the nares and, at the sides the apertures of the Eustachian tubes ; while,
below the velum, there is first the passage leading from the mouth, then the
superior opening of the larynx, and lastly the passage into the oesophagus.
The walls of the pharynx consist of a fascia or layer of fibrous tissues,
named the pharyngeal apoueurosis, dense at its upper part but lax and
weak below, surrounded by muscles, and lined by a mucous membrane.
At its upper end this fibrous wall is attached to the posterior margin of the
body of the sphenoid bone, and passes outwards to the petrous portion of
the temporal. It is strengthened in the middle line by a strong band de-
scending between the recti antici muscles from a part of the basilar process
which often presents a marked tubercle.
The pharynx is usually described as attached superiorly to the basilar process
of the occipital bone ; it is certain, however, from dissections in both young and old
subjects, that the recti capitis antici muscles come quite forward to the anterior ex-
tremity of the basilar process ; that the posterior wall of the pharynx at its upper end
forms a cul-de-sac on each side opposite the tip of the petrous bone, and lies in a
curve, with its convexity forwards, in front of the recti muscles ; and that the only
connection of the pharynx with the occipital bone is by means of the mesial band,
which has been described, and which forms a cranio-pharyngeal ligament. The
tubercle from which this band principally springs is sometimes named tuberculum
pharyngeum,
Behind, the wall of the pharynx is loosely connected by areolar tissue
to the prevertebral fascia covering the bodies of the cervical vertebrae and
the muscles which rest upon them. At the sides, the walls have similar
connections, by loose areolar tissue, with the styloid process and its muscles,
and with the large vessels and nerves of the neck. In front, they are
attached in succession to the sides of the posterior nares, the mouth and
the larynx. Thus, commencing above by a tendinous structure only, at the
petrous portion of the temporal bone and the Eustachian tube, the walls are
connected by means of muscle and fibrous membrane, first, with the inter-
nal pterygoid plate, then with the pterygo-maxillary ligament, and next
with the mylo-hyoid ridge of the lower jaw ; below this, they are attached
3 H 2
820
THE PHARYNX.
to the sides of the tongue, to the hyoid bone, and stylo-hyoid ligament ;
and, still lower down, to the thyroid and cricoid cartilages.
The pharynx is about four iuches and a half in length, and is considerably
wider across than it is deep from before backwards. Its width above is
moderate ; its widest part is opposite the cornua of the hyoid bone, and
below tbis it rapidly contracts towards its termination, opposite the cricoid
cartilage, where it is narrowest.
Structure. — The muscles of the pharynx are the superior, middle and
inferior constrictors, the stylo-pharyngeus, and the palato-pharyngeus.
They are described at page 187.
The mucous membrane lining the inner surface of the pharynx is con-
tinuous at the several apertures with that of the adjacent cavities. It
varies somewhat in its character in different parts. Its upper portion is
Fig. 575.
Fig. 575. — ANTERO-POSTERIOR VERTICAL SECTION THROUGH THE HEAD A LITTLE TO THE
LEFT OP THE MlDDLE LlNE, SHOWING THE RELATIONS OP THE NASAL AND BuCCAL
CAVITIES, THE PHARYNX, LARYNX, &c.
a, nasal septum, and below it the section of the hard palate ; b, the tongue ; c, soft
palate ; d, the lips ; u, the uvula ; r, anterior pillar of the fauces ; i, posterior pillar ;
t, the tonsil placed between the pillars ; p, upper part of the pharynx ; h, body of the
hyoid bone ; k, thyroid cartilage ; n, cricoid cartilage ; v, on the upper vocal cords above
the glottis ; s, epiglottis ; 1, posterior opening of the nares ; 3, behind the isthmus
faucium ; 4, opposite the superior opening of the larynx ; 5, passage into the oesophagus ;
6, opening of the right Eustachian tube.
thick where it adheres to the periosteum of the basilar process, but is much
thinner near the entrance of the Eustachian tube and the posterior nares :
in this situation numerous glands are found collected in a layer beneath the
mucous membrane. The glands are of two kinds, viz., racemose, which are
especially numerous in the upper portion ; and simple or compound follicular,
which exist throughout the whole of the pharynx. A chain of glands forming
a glandular mass, exactly similar to that of the tonsils, stretches across the
THE (ESOPHAGUS. 821
back of the fauces between the orifices of the two Eustachian tubes (Kolli-
ker). In the part opposite the fauces, the mucous membrane exactly re-
sembles that of the mouth. Lower down it becomes paler, and at the back
of the larnyx it forms several longitudinal folds or plica;. According to
Henle, the epithelium upon the upper portion of the pharynx, as low down
as a horizontal line level with the floor of the nares, is columnar and cili-
ated ; but, below that point, it is squamous and destitute of cilia.
THE OESOPHAGUS.
The oesophagus or gullet, the passage leading from the pharynx to the
stomach, commences at the cricoid cartilage opposite the lower border of
the fifth cervical vertebra, and, descending along the front of the spine,
passes through the diaphragm opposite the ninth dorsal vertebra, and there
ends by opening into the cardiac orifice of the stomach.
The length of the oesophagus is about nine or ten inches. It is of
smaller diameter than any other division of the alimentary canal, its nar-
rowest part being at the commencement behind the cricoid cartilage ; it is
also slightly constricted in passing through the diaphragm, but, below thac,
gradually widens into the stomach. The oesophagus is not quite straight in
its direction, but presents three slight curvatures, One of these is an antero-
posterior flexure, corresponding with that of the vertebral column in the
neck and thorax. The other two are slight lateral curves ; for the oesophagus,
commencing in the median line, inclines to the left side as it descends to
the root of the neck ; thence to the fifth dorsal vertebra it gradually resumes
the mesial position ; and finally, it deviates again to the left, at the same
time coming forward towards the oesophageal opening of the diaphragm.
In the lower cervical and upper dorsal region the oesophagus is applied
to the anterior surface of the spine, being connected with it and with
the lougus colli muscle by loose areolar tissue ; but between it and the bodies
of the upper dorsal vertebrae the thoracic duct ascends obliquely from right
to left : its lower third is placed in front of the aorta. In the neck, the
oesophagus lies close behind the trachea, and the recurrent laryngeal nerves
ascend in the angles between them ; on each side is the common carotid
artery, and also a part of the thyroid body, but, as the oesophagus
inclines to the left side, it is in more immediate connection with the left
carotid.
In the thorax, the oesophagus is successively covered in front by the
lower part of the trachea, by the commencement of the left bronchus, and
by the back of the pericardium. The aorta, except near the diaphragm,
where the oesophagus is in front of the vessel, lies rather to the left, and
the vena azygos to the right ; the pneumogastric nerves descend in close
contact with its sides, and form a plexus around it, the left nerve proceeding
gradually to the front, and the right nerve retiring behind it. Lastly, the
oesophagus, which is here placed in the interval between the two pleurae,
comes partially in contact with both of those membranes.
Structure. — The walls of the oesophagus are composed of three coats ; viz.,
an external or muscular, a middle or areolar, and an internal or mucous
coat. Outside the muscular strata, there is a layer of fibrous tissue, with
well marked elastic fibres, which is sometimes spoken of as a distinct
coat.
The muscular coat consists of an external longitudinal layer, and an
internal circular layer. This twofold arrangement of the muscular fibres
822
THE (ESOPHAGUS.
prevails throughout the whole length of the alimentary canal ; but the two
layers are here much thicker, more uniformly disposed, and more evident
than in any other part except quite at the lower end of the reotum. The
external or longitudinal fibres are disposed at the commencement of the
tube in three fasciculi, one in front, and one on each side of the oeso-
phagus. The lateral fasciculi are blended above with the inferior constrictor
of the pharynx ; the anterior fasciculus arises from the back of the cricoid
cartilage at the prominent ridge between the posterior crico-arytenoid
muscles, and its fibres spreading out obliquely on each side of the gullet as
they descend, soon blend with those of the lateral bundles to form a con-
tinuous layer around the tube. The internal or circular fibres are separated
Fig 576. Fig. 576. — SECTION OP THE COATS OP THE
HUMAN (ESOPHAGUS (from Kolliker). ^~
The section is transverse, and from near
the middle of the gullet, a, fibrous covering ;
b, divided fibres of the longitudinal mus-
cular coat ; c, transverse muscular fibres ;
d, submucous or areolar layer ; e, mucous
membrane ; /, its papillae ; g, laminated
epithelial lining ; h, opening of a mucous
gland, of which the cellular part is seen
embedded deeply in the mucous membrane ;
i, fat-vesicles.
above by the fibres of the longi-
tudinal fasciculi from those of the
inferior constrictor of the pharnyx.
The rings which they form around
the tube have a horizontal direction
at the upper and lower part of the
oesophagus, but in the intervening
space are slightly oblique. At the
lower end of the oesophagus, both
layers of fibres become continuous
with those of the stomach.
The muscular coat of the upper
end of the oesophagus is of a well-
marked red colour, and consists of
striped muscular fibres ; but lower
down it becomes somewhat paler, and is principally composed of the plain
muscular fibres. A few striped fibres, however, are found mixed with the
others, and have been traced throughout its whole length, and even, it is
said, upon the cardiac end of the stomach. (Ficinus.)
The longitudinal fibres of the oesophagus are observed by Hyrtl to be sometimes
joined by a broad band of smooth muscle, passing upwards from the left pleura, and
sometimes also by another from the left bronchus.
The areolar coat is placed between the muscular and mucous coats, and
connects them loosely together.
The mucous membrane is of firm texture, and is paler in colour than that
of the pharynx or stomach. From its loose connections its outer surface is
freely movable on the muscular tunic ; and when the latter is contracted,
as happens when the oesophagus is not giving passage to food, the mucous
lining is thrown into longitudinal folds, the inner surfaces of which are in
mutual contact. These folds again disappear on distension of the canal.
THE (ESOPHAGUS.— THE ABDOMEX. 823
Minute papillae are seen upon this mucous membrane, placed at some
distance from each other, and the whole is covered with a thick squamous
epithelium, which can be traced as far as the cardiac orifice of the stomach,
where it suddenly passes into one of a different character, as will be here-
after noticed.
The gullet is provided with many small compound racemose glands, named
cesophageal glands, which are especially numerous at the lower end of the
tube.
Dilatations occasionally occur in the course of the oesophagus. Diverticular pouches
are also sometimes found, but appear in all cases to be of hernial origin. Duplicity
of the oesophagus in part of its extent, without other abnormality, has been recorded
(Blaes, quoted by Meckel).
THE ABDOMINAL PORTION OF THE DIGESIIVE OEGANS.
As that part of the digestive canal which is found beneath the diaphragm,
and consists of the stomach and intestines, is situated within the cavity
of the abdomen, and occupies, together with the liver (the secretion of
which it receives), by far the greater part of that cavity, the topographic
relations of the abdominal viscera may here be briefly explained.
THE ABDOMEN.
The abdomen is the largest cavity in the body, and is lined by an exten-
sive and complicated serous membrane, named the peritoneum.
It extends from the diaphragm above to the levatores ani muscles
below, and is subdivided into two parts : an upper and larger part, the
abdomen, properly so called ; and a lower part, named the pelvic cavity.
The limits between the abdominal and pelvic portions of the cavity are
marked by the brim of the pelvis.
The enclosing Avails of this cavity are formed principally of muscles and
tendons which have been already described (p. 248). They are strengthened
internally by a layer of fibrous tissue lying between the muscles and the
peritoneum, the different parts of which are described under the names
of fascia transversalis, fascia iliaca, and anterior lumbar fascia (p. 257).
These walls are pierced by several apertures, through which are transmitted
the great vessels and some other parts, such as the several diaphragmatic
apertures for the aorta, vena cava, and oesophagus, and the femoral arches
and inguinal canals. In the median fibrous substance of the anterior wall
lies the umbilical cicatrix. The cavity of the pelvis is also lined with strong
fasciae (p. 260), and partially by peritoneum, and at its lower part it presents
the apertures for the transmission of the rectum and the genito-urinary
passages.
For the purpose of enabling precise reference to be made to the situation
and condition of the contained organs, the abdomen proper has been arti-
ficially subdivided into certain regions, the boundaries of which are indicated
by lines drawn upon the surface of the body. Thus, two horizontal lines
drawn round the body divide the cavity into three zones : viz. an upper, a
middle, and a lower. One of these lines, commencing at the most prominent
point of the lower costal cartilages of one side, is drawn across to the cor-
responding point on the opposite side, and thence horizontally round the
back to the place at which it began. The other line, proceeding from the
crest of the ilium of one side, extends to that of the other, and so round the
body, as in the former instance. Each of these zones again is subdivided
824
THE ABDOMEN.
into three parts by means of two perpendicular lines, drawn from the carti-
lage of the eighth rib, on each side, down to the centre of Poupart's liga-
ment.
The upper zone is thus marked off into the right and left hypochondriac
regions and the epigastric region, the depression in the upper part of which
is called scrobiculus cordis, or pit of the stomach. The middle zone is
divided into the umbilical region in the centre, and the right and left
lumbar regions ; and the inferior zone into the hypogastric region in the
centre, and the iliac region at each side.
On opening the abdominal cavity from the front, the viscera are seen to
lie in an upper and a lower group, separated by the great omentum, which
overhangs those in the lower part. The surfaces, which are in contact one
with another, and with the wall of the cavity, are rendered glistening by
reflections over them of the lining membrane of the cavity, the peritoneum ;
and the various organs are found to be attached by means of folds or dupli-
catures of that membrane, termed mesenteries and omeuta, which include the
blood-vessels, nerves, and lymphatics belonging to each organ. In the
upper group, as seen from before, are comprised the liver, stomach, and
a small part of the intestine ; in the lower group, more or less hidden by
Fig, 577. Fig. 577. — OUTLINE OP THE ANTERIOR
SURFACE OP THE ABDOMEN, SHOWING
THE DIVISION INTO REGIONS.
], epigastric region ; 2, umbilical; 3,
hypogastric ; 4, 4, right and left hypo-
chondriac ; 5, 5, right and left lumbar ;
6, 6, right and left iliac.
the great omentum, are the re-
maining parts of the alimentary
canal. The spleen, pancreas, and
kidneys constitute a deeper group.
On the right side, projecting
downwards from beneath the dia-
phragm, is the liver with its ex-
cretory apparatus, which occupies
the right hypochondrium and part
of the epigastrium aud extends a
short way into the left hypochon-
drium ; to the left, and partly
beneath the liver, is the stomach,
which lies in the epigastric and left
hypochondriac regions ; and closely applied to the left or cardiac end of the
stomach is the spleen.
The stomach is seen to be connected at its right extremity, named the
pylorus, with the small intestine. The first part of the small intestine,
named duodenum, forms a deep curve projecting towards the right side,
resting on the posterior wall of the abdominal cavity and right kidney, and
terminating at the left of the middle line, where it emerges from behind the
root of the mesentery, and passes into the second part of the intestine, named
jejunum. The hollow of the curve of the duodenum is occupied by the large
right extremity or head of the pancreas. The remainder of the small in-
testine, comprising the jejunum in its upper two-fifths, and the ileum in the
SITUATION OF THE ABDOMINAL VISCERA.
825
lower three-fifths, is disposed in moveable convolutions, and is attached
posteriorly by a broad mesentery to the abdominal wall. It occupies the
umbilical and hypogastric regions, from the back parb of which the mesen-
tery takes origin, and it extends likewise into the lumbar and iliac regions,
besides gravitating into the pelvis. The ileum terminates abruptly in the
right iliac region in the caput ccecum, a cul-de-sac in which the great intestine
commences. The caecum is continued into the ascending colon, which lies
against the posterior wall of the abdomen, as it passes up through the right
lumbar to the right hypochondriac region. The ascending colon is succeeded
by the transverse colon which passes transversely, or with a pendulous curve,
across the abdomen from right to left, resting on the small intestines. Below
Fig. 578. — DIAGRAM OF THE ABDO- Fig. 578.
MINAL PART OF THE ALIMENTARY
CANAL. ^
1, the stomach ; 2, the lower part
of the gullet ; 3, the left cul-de-
sac, aud, 4, the pyloric end of the
stomach ; 5, 6, the duodenum ; 7,
8, convolutions of the small intes-
tine ; 9, caecum ; 10, the vermi-
form process ; 11, ascending, 12,
transverse, and, 13, descending
colon ; 14, commencement of the
sigmoid flexure ; 15, rectum.
the spleen, the transverse
colon is continued into the
descending colon which extends
down through the left lumbar
to the left iliac region, where
it is continued into the more
loosely bound sigmoid flexure,
which occupies that fossa and
falls into the rectum.
Within the pelvis, the ex-
tension downwards of the
peritoneal cavity is termed
the recto-ve&ical fossa : pos-
teriorly the rectum is ob-
served, and anteriorly the
sloping upper wall of the
urinary bladder ; while, in
the female, the uterus projects
upwards between the rectum
and bladder, so that a recto-
uterine pouch is formed, and
the ovaries and Fallopian
tubes are pendant at its sides.
The bladder when full, and
the uterus in its gravid state,
project upwards into the abdomen, and displace more or less of the small
intestine.
Subjoined is an enumeration of the organs situated in the different
regions of the abdomen.
826
THE ABDOMEN. -THE PERITONEUM.
PARTS SITUATED IN EACH REGION OF THE ABDOMEN.
Epigastric region
Hypochondriac, right
Hypochondriac, left .
Umbilical ....
Lumbar, right
Lumbar, left . . .
Hypogastric . .
Iliac, right . . .
Iliac, left .
The middle part of the stomach, with its pyloric
extremity, the left lobe of the liver, the hepatic
vessels and lobulus Spigelii, the pancreas, the
coeliac axis, the semilunar ganglia, part of the
vena cava, and also, as they lie between the crura
of the diaphragm, part of the aorta, the vena
azygos and thoracic duct.
The right lobe of the liver, with the gall-bladder,
part of the duodenum, the hepatic flexure of the
colon, the right suprarenal capsule, and part of
the corresponding kidney.
The large end of the stomach, with the spleen and
narrow extremity of the pancreas, the splenic
flexure of the colon, the left suprarenal capsule
and upper part of the left kidney. Sometimes
also a part of the left lobe of the liver.
Part of the omentum and mesentery, the transverse
part of the colon, transverse part of the duodenum,
with some convolutions of the jejunum and ileum.
The ascending colon, lower half of the kidney and
part of the duodenum and jejunum.
The descending colon and lower part of the left kidney,
with part of the jejunum.
The convolutions of the ileum, the bladder in
children, and, if distended, in adults also ; the
uterus when in the gravid state.
The caecum, appendix vermiformis, ileo-caecal valve,
ureter, and spermatic vessels.
The sigmoid flexure of the colon, the ureter and
spermatic vessels.
THE PERITONEUM.
The peritoneum or serous membrane of the abdominal cavity is by far the
most extensive and complicated of the serous membranes. Like the others
it may be considered to form a shut sac, on the outside of which are placed
the viscera which it covers. In the female, however, the two Fallopian
tubes open at their free extremities into the cavity of the peritoneum. The
internal surface is free, smooth, and moist, and is covered by a thiu
squamous epithelium. The external or attached surface adheres partly to
the parietes of the abdomen and pelvis, and partly to the outer surface of
the viscera situated within them. The parietal portion is connected loosely
with the fascia lining the abdomen and pelvis by means of a layer of areolar
tissue, distinct from the abdominal fasciae, and named the subperitoneal or
retro-peritoneal layer ; but it is more firmly adherent along the middle line
of the body in front, as well as to the under surface of the diaphragm. Tho
visceral portion, which is thinner than the other, forms a more or less
perfect investment to most of the abdominal and pelvic viscera.
The folds of the peritoneum are of various kinds. Some of them,
constituting the mesenteries, connect certain portions of the intestinal canal
with the posterior wall of the abdomen ; they are, the mesentery properly
so called for the jejunum and ileum, the rneso-csecum, transverse and sig-
moid meso-colon, and the meso-rectum. * Other dnplicatures, which are
called omenta, proceed from one viscus to another ; they are distinguished
as the great omeutum, the small omentum, and the gastro-spleuic orneiituni.
Lastly, certain reflexions of the peritoneum from the walls of the abdomen or
pelvis to viscera which are not portions of the intestinal canal, are named liga-
ments : these include the ligaments of the liver, spleen, uterus, and bladder.
INFLECTIONS OF THE PERITONEUM. 827
If the examination of the folds of the peritoneum be commenced on the
under surface of the diaphragm, it will be found that on the left side it can
be traced back to the posterior wall of the abdomen, and down in front of the
upper part of the kidney to the commencement of the descending colon.
Further to the right, it is reflected from the diaphragm over the front of
the stomach, and from the left of the stomach passes across a very short
interval to the spleen, which it completely invests ; and it is continued back
from the spleen to the abdominal wall. Still further to the right, the
peritoneum is reflected from the diaphragm to the liver, invests the whole
superior surface of that organ, and passes round its anterior and lateral
margins to invest the whole of its inferior surface, with the exception only
of so much as lies behind the portal fissure, viz., the lobule of Spigelius.
On the upper surface of the liver the peritoneum is thrown into a right and
a left fossa by a vertical antero-posterior fold attaching it to the diaphragm,
which is named the falciform, or suspensory ligament of the liver. In the
lower margin of this ligament a fibrous cord, consisting of the obliterated
remains of the umbilical vein, and named the round ligament of the liver,
extends upwards from the umbilicus to the longitudinal fissure which divides
inferiorly the right lobe of the liver from the left ; and it is the reflection of
the peritoneum from this cord which forms the falciform ligament. The
thick posterior border of the liver, uninvested with peritoneum, is in contact
with the diaphragm ; and the reflexions of peritoneum from the upper and
under surfaces of the organ to the parietes above and below this border con-
stitute the coronary ligament. Towards the right and left extremities of
the liver the superior and inferior layers of the coronary ligament come into
contact for a little way, and form the right and left triangular ligaments of
the liver.
The portion of peritoneum reflected from the under surface of the liver, ,
opposite the portal fissure, passes down over the vena portse, hepatic artery,
and biliary ducts, to the pyloric extremity of the stomach and first part of
the duodenum ; while that which invests the part of the liver to the right
of the portal fissure is conducted back to the posterior wall of the abdomen.
If now, the disposition of the peritoneum be examined in the spot where
those two modes of arrangement meet, an aperture sufficiently large to
admit a finger, and furmed by invagination of the peritoneum, will be found
leading, from right to left, behind the hepatic vessels and duct : this aper-
ture is the foramen of Winslow ; and the fold of peritoneum in front of it,
containing the portal vein, hepatic artery, and biliary ducts, is termed the
small or gastro-hepatic omentum. The foramen of Winnlow has above it a
portion of the liver ; behind it the vena cava inferior ; below it the duodenum ;
and in front the small omentum. The invagination of peritoneum which
takes place at the foramen of Winslow is of great extent, expanding to form
a large pouch, which lies behind the stomach, and stretches downwards to a
variable degree in front of the transverse colon. This is the sac of the
omentum or smaller cavity of the peritoneum, which will be presently
described.
On tracing downwards the peritoneum investing the anterior surface of
the stomach, it is seen to be prolonged from the inferior border of that
viscus to form a pendulous fold of omentum lying loosely in front of the
colon and small intestines, and having a free margin iuferiorly. Folding
backwards on itself at this margin, the peritoneum passes upwards to the
transverse colon and becomes adherent to its surface, whence it is continued
back to the abdominal wall.
828
THE PERITONEUM.
The sac of the omentum may be laid open by means of an incision a little
Fig. 579.
Fig. 579, A.— DIAGRAMMATIC OUTLINE OP A
SUPPOSED SECTION OP THE BODY, SHOWING
THE INFLECTIONS OF THE PERITONEUM IN
THE FEMALE. £
The upper part of the section is a little to
the right of the mesial plane of the body,
through the quadrate and Spigelian lobes of
the liver ; below it is supposed to be mesial :
I c, placed above the diaphragm opposite to
Ihe coronary ligament of the liver ; Z, the
liver ; I', lobe of Spigel ; s, stomach. ; c,
transverse colon ; i, the small intestine ;
p a, pancreas ; a, the aorta ; d, the duode-
num ; v, urinary bladder ; u, uterus ; r,
rectum ; tj, its middle part opened ; v a,
vagina; p, p, the parietal peritoneum lining
the front and back of the abdominal cavity ;
the line representing the inflections of the
greater sac of the peritoneum will be traced
from the neighbourhood of I c, where it
passes on the upper surface of the liver over
the upper and lower surfaces of that organ,
in the front of g h, the gastro-hepatic omen-
tum, over the front of the stomach, down
to 0', the outer layer of the great omentum,
whence it passes back to the vicinity of
the pancreas, and re-descends as the upper
layer of the transverse meso-colon ; after
enclosing the colon it returns on the lower
surface of the transverse meso-colon, m c, to
the root of the mesentery, m ; it now forms
the mesentery and encloses the small in-
testine, returning to the duodenum and
posterior wall of the abdomen, whence it
passes over the rectum, r, descends into the
recto-vaginal pouch, u\ covers the back
and front of the uterus and the bladder
partially and regains the anterior abdominal
wall above the pubes ; as connected with
the lesser sac of the peritoneum, w, marks
the position of the foramen of Winslow as if
seen in perspective beyond the section ; the
lesser sac with the sac of the omentum is
shaded with horizontal lines, and is marked
o o : round this space the line of the peri-
toneum may be traced from the diaphragm
over the lobe of Spigel, to the back of the
gastro-hepatic omentum, thence behind the
stomach and down into the sac of the omen-
tum ; it then ascends to the pancreas,
which it covers, and thence reaches again,
the diaphragm.
B, is a sketch of part of a section similar
to that of A, but showing the different view
frequently taken, according to which the
two layers of the meso-colon, after enclosing
the colon, descend to form the posterior pair
of the layers of the great omentum.
below the great curvature of the
stomach. It will then be seen that the
inner wall of this sac, having invested
SAC OF THE OMEXTUM. 829
the posterior surface of the stomach and commencement of the duodenum,
is continued downwards, back to back with the general peritoneum, into
the pendulous portion of the omentum, and, as it returns thence, is applied
to the anterior surface of the transverse colon. Passing these parts, it
resumes its position of proximity to the peritoneum of the greater sac,
and proceeds to the posterior wall of the abdomen. The two layers of peri-
toneum which thus hang pendulously one within the other, and are derived
from the general and the smaller sac, constitute the yastro-colic or great
omentum ; while those by which the transverse colon is connected with the
abdominal wall are termed the transverse mesocolon. In the pendulous great
omentum, there being a duplication of both the general peritoneum and
the wall of the smaller sac, four layers are to be distinguished, viz., first,
an anterior and a posterior layer belonging to the greater sac of the peri-
toneum, having their smooth surfaces respectively directed forwards to the
abdominal wall and backwards to the small intestines ; and second, between
these, the anterior and posterior layers derived from the lesser sac, lining
the omental cavity and gliding one against the other : these four layers are,
however, so intimately united and reduced to such extreme tenuity in the
adult, that they cannot be separately recognised in the omentum below
the colon. In most instances the pendulous part of the omentum presents
the appearance of lacework, the interstices of which in corpulent persons
are more or less loaded with fat. In some subjects, instead of lying like
an apron over the small intestine, it is crumpled into a bundle along the
transverse colon, as if displaced by the movements of the intestines against
the wall of the abdomen.
The description now given of the great omentum and transverse meso-
colon agrees with the appearances most frequently seen in the adult subject,
and with the account usually given in English works of Anatomy, the pos-
terior layer of the great omentum being described as separating from
the layer within, belonging to the omental sac, when it reaches the trans-
verse colon, so as to pass behind or below that viscus, and from thence
as proceeding backwards to the abdominal wall as the posterior or lower
layer of the transverse meso-colon. It was, however, long ago pointed
out by Haller, and the view has been confirmed by the observations of
J. F. Meckel, J. Miiller, Hansen, and Huschke, that in the foatus, and
occasionally in the child, or even in the adult, the two posterior layers
of the omentum, though adherent to the transverse colon, may be separated
from it and from the transverse meso-colon, so as to demonstrate that the
transverse meso-colon is really a distinct duplicature of peritoneum. This
view has been adopted by Hoi den and Luschka in their more recent works,
and has been verified by Allen Thomson. Figures 579 A, and B, show
diagrammatically the difference of the two views.
The anterior wall of the sac of the omentum invests the whole posterior
surface of the stomach ; above the small curvature of the stomach it lies
back to back with the general peritoneum, completing in conjunction with
it a gastro-phrenic ligament ; and further to the right it forms the posterior
layer of the gas tro -hepatic omeutum, and likewise invests the lobulus Spigelii
of the liver, close to the foramen of Wiuslow. Lying transversely in front
of the aorta and in contact with the posterior wall of the abdomen, the
pancreas is seen invested anteriorly by the hinder wall of the sac of the
omentum. To the left of the stomach the sac extends to the spleen, and
usually gives investment to a small portion of that organ at the lower end
of its hilus \ it thus forms the posterior layer of the gastro splenic omentum,
830 THE PERITONEUM.
the fold by which the spleeu is attached to the stomach. The splenic
artery lies behind the sac of the omentum in its course to the spleen, but
its gastric branches turn round the splenic margin of the sac and reach the
stomach by that means. The coronary artery of the stomach reaches the
front of the sac by turning round its upper margin ; and the hepatic artery
passes round from below, close to the foramen of Winslow.
The disposition of the peritoneum below the level of the transverse meso-
colon is comparatively simple. The mesentery of the small intestine,
although greatly frilled out in front to correspond in length with the
jejunum and ileum to which it affords support, is attached posteriorly by a
very short border which extends from the level of attachment of the trans-
verse colon immediately to the left of the middle line, directly down to the
right iliac fossa, where the ileum falls into the caecum. At its widest part
the length of the mesentery is from four to six inches between its vertebral
and its intestinal border. Between the two layers of serous membrane of
which it consists are placed, beside some fat, numerous branches of the
superior mesenteric artery and vein, together with nerves, lacteal vessels,
and mesenteric glands. In the right and left lumbar region the peritoneum
invests the ascending and descending colon usually in less than their whole
circumference, and thus binds them closely down to the abdominal parietes,
without the intervention of a meso- colon. In some cases the caecum is
suspended at a short distance from the right iliac fossa, by a distinct dupli-
cature of the peritoneum, which is termed the mcso-ccecum ; but, more
commonly, the peritoneum merely binds down this part of the large intes-
tine, and forms a distinct but small mesentery for the vermiform appendix
only. The sigmoid flexure is attached to the left iliac fossa by a consider-
able mesentery, the sigmoid meso-colon ; and in the pelvis the rectum is
attached by a fold named meso-rectum. The other peritoneal folds within
the pelvis will be mentioned elsewhere.
Along the colon, and upper part of the rectum, the peritoneum is de-
veloped into numerous little projections filled with adipose tissue. These
fatty processes are named appendices epiploicce.
At the upper end of the attachment of the mesentery, on its left side,
there is always visible a small portion of the terminal part of the duode-
num appearing from underneath in about half its breadth ; and on the
right side of the mesentery there is often another little angle of duodenum
visible between the mesentery and meso-colon. Thus it will be observed
that, while the commencement of the duodenum is invested, like the sto-
mach, in front by the general peritoneum and behind by the sac of the
omentum, and a succeeding portion is invested only in front, the remainder
is crossed by the colon and mesentery, and is only to a small extent in
contact with peritoneum.
THE STOMACH.
The stomach is that dilated portion of the alimentary canal which inter-
venes between the oesophagus and the duodenum, and within which the
food is retained for a time to be acted on by the gastric juice, and to be
converted into chyme.
This organ is seated in the left hypochondriac and the epigastric regions,
extending also into the right hypochondrium. It lies in part against the
anterior wall of the abdomen, and in part beneath the liver and diaphragm,
and above the transverse colon.
THE STOMACH-FORM, SITUATION, &c. 831
The stomach is of a somewhat conical or pyriform shape. The left ex-
tremity is the larger, and is named the cardiac, great or splenic end. The
right or small end is also named the pyloric extremity. Of its two orifices,
the one by which food enters from the ossophagus is named the cardiac
orifice, the other, by which it passes into the duodenum, and which is placed
on a somewhat lower level, and more forwards, is the pyloric orifice.
The oesophagus terminates in the stomach two or three inches from the
great extremity, which projects beyond the place of union to the left,
forming the great cul-de-sac or fundus.
Between the cardiac and the pyloric orifices, the outline of the stomach
is curved along its upper and lower borders. The upper border, about
three or four inches in length, is concave, and is named the lesser curvature ;
while the lower border, which is much longer, and, except towards the
pylorus, convex, forms the greater curvature.
Fig. 580. — DIAGRAMMATIC OUTLINE OP Fig. 580.
THE STOMACH. £
«, great curvature ; 6, lesser curva-
ture ; c, left end, great cul-de-sac, or
fundus ; d, small cul-de-sac or antrum
pylori; o, oesophageal orifice or cardia;
p, duodenal orifice or pylorus.
Towards the pylorus, the small
end of the stomach describes a
double bend, opposite to the first
turn of which is a prominence or
bulging, sometimes named the
small cul-de-sac or antrum pylori.
Division of the stomach, by constriction, into a right and left pouch, is frequently
observed as a temporary condition resulting from spasm. More rarely it is of a per-
manent character (Struthers, Monthly Med. Journ., 1851).
Dimensions. — These vary greatly, according to the state of distension
of the organ. When moderately filled, its length is about ten or twelve
inches ; and its diameter at the widest part, from four inches to four inches
and a half. According to Clendiuning, it weighs, when freed from other
parts, about four ounces and a half in the male, and somewhat less in the
female.
Connections. — The borders of the stomach are connected with folds of
peritoneum in their whole extent. Thus, to the superior border is attached
the gastro-phrenic ligament and gastro-hepatic omentum ; to the inferior
border is attached the gastro-colic omentum ; and to the left extremity the
gastro-spleuic omentum. The blood-vessels and lymphatics of the stomach
pass within these duplicatures of the peritoneum, and reach the organ along
its two curvatures. Its anterior and posterior surfaces are free, smooth, and
covered with peritoneum. The anterior surface, which is directed upwards
as well as forwards, is in contact above with the diaphragm and the under
surface of the liver, and lower down with the abdominal parietes opposite to
the epigastric region, which is hence named the pit of the stomach. The
posterior surface is turned downwards and backwards, and rests upon the
transverse meso-colon, and farther back, upon the pancreas and great vessels
of the abdomen.
832 THE STOMACH.
At its cardiac orifice it is continuous with the oesophagus, and is, there-
fore, fixed to the cesophageal opening in the diaphragm. The pyloric ex-
tremity, situated lower down, nearer to the surface, and having greater
freedom of motion, is continuous with the duodenum. It is covered by the
concave surface of the liver, and in some cases touches the neck of the gall-
bladder.
When the stomach is distended, its position and direction are changed.
The O3sophageal end, being fixed to the back part of the diaphragm, cannot
undergo any considerable change ; but the duodenal extremity has more
liberty of motion. The lesser curvature is, also, somewhat fixed to the
liver by the small omentum, while the great curvature is the most movable
part : accordingly, when the stomach is distended, this curvature is elevated
and at the same time carried forwards, whilst the anterior surface is turned
upwards, and the posterior surface downwards.
Structure. — The walls of the stomach consist of four distinct coats, held
together by fine areolar tissue. They are named, in order from without in-
wards, the serous, muscular, areolar or submucous, and mucous coats. By
some the areolar coat is not reckoned as a separate tunic. Taking all the
coats together, the walls of the stomach are thinner than those of the
oesophagus, but rather thicker than those of the intestines generally.
They are thickest at the pyloric end, and thinnest in the great cul-de-
sac.
The external or serous coat, derived from the peritoneum, is a thin,
smooth, transparent, and elastic membrane which closely covers the entire
viscus, excepting along its two curvatures. Along the line of these curvatures
the attachment is looser, leaving an interval occupied by the larger blood-
vessels.
The second or muscular coat is composed of three sets of unstriped fibres,
disposed in three layers, and named, from their direction, the longitudinal,
the circular, and the oblique fibres.
The first or outermost layer consists of the longitudinal fibres, which are
in direct continuity with those of the oesophagus. They spread out in a
radiating manner from the cardiac orifice, and are found in greatest abun-
dance along the curvatures, especially on the lesser one. On the anterior
and posterior surfaces they are very thinly scattered, or are scarcely to be
found. Towards the pylorus they are arranged more closely together and
form a thicker uniform layer, which, passing over the pylorus, becomes con-
tinuous with the longitudinal fibres of the duodenum.
The second set consists of the circular fibres, which form a complete layer
over the whole extent of the stomach. They commence by small and thinly
scattered rings at the left extremity of the great cul-de-sac, describe larger
and larger circles as they surround the body of the stomach concentric to its
curved axis, and towards the pyloric end again form smaller rings, and at
the same time become much thicker and stronger than at any other point.
At the pylorus itself, they are gathered into an annular bundle, which pro-
jects inwards into the cavity, and forms, together with areolar tissue and the
lining mucous membrane, the pyloric sphincter and valve. Some of the
circular fibres appear to be continued from those of the oesophagus, spreading
from its right side. According to Pettigrew the fibres of this layer are not,
as usually described, mere rings or circles, but rather double loops in the
form of the figure of eight, the two parts of which cross each other very
obliquely.
The innermost muscular layer is incomplete, and consists of the oblique
MUSCULAR COAT OF THE STOMACH.
833
fibres. These oblique fibres are continuous with the layer of circular fibres
of the gullet ; they embrace the cardiac orifice on the left, where they form
a considerable stratum, and from that point descend obliquely upon the
Fig. 580*. — SKETCH
OF THE DISTRI-
BUTION OP MUS-
CULAR FIBRES IN
THE STOMACH (af-
ter Pettigrew and
from nature). - g
A, external layer
of longitudinal fi-
bres, as seen from
the outside ; B,
middle layer of cir-
cular fibres as seen
on removing the
longitudinal layer ;
C, deepest layer of
oblique fibres as
seen from within,
after inverting the
stomach and remov-
ing the mucous
membrane : c, the
cardiac end ; p, the
pyloric end ; in A,
the stronger longi-
tudinal fibres pass-
ing along the lesser
and greater curva-
tures, and all round
the pyloric end, are
shown, and the radi-
ating fibres spread-
ing from the root of
the gullet over the
front and back of the
stomach ; in B,- the
nearly uniform layer
of circular fibres in
two sets crossing each
other very obliquely,
and becoming con-
centric at the car-
diac end to the cen-
tre of the great cul-
de-sac ; in C, the
very oblique bands
of fibres which form
a continuation of the
circular fibres of the
gullet and spread in
two sets, o, o', one
from the right and
the other from the
left side of the car-
dia (also partially re-
presented in B), pass-
ing over the front and
back of the stomach
(exceptits lessercur-
vature) as far as the pyloric end.
Fig. 580*.
3 i
834
THE STOMACH.
anterior and posterior surfaces of the stomach, where they spread out from
one another, and most of them gradually disappear ; some, however, reach
as far as the pylorus. A similar set of fibres, noticed by Henle, and more
fully described by Pettigrew, proceed from the right side of the cardia and
spread over the front and back of the great cul-de-sac : these are in part
continuous with the circular layer. The oblique fibres are best seen from
the inside of the stomach, after removing the mucous membrane. In this,
as in the circular layer of fibres, Pettigrew believes the figure-of-8 arrange-
ment to prevail. (From unpublished Notes of Researches on the Muscular
Fibres of the Stomach, by James Pettigrew, M. D. )
Fig. 581. — DIAGRAMMATIC VIEW IN PERSPECTIVE
OP A PORTION OP THE COATS OF THE STOMACH
AND DUODENUM, INCLUDING THE PYLORUS, f
g, the alveolar surface of the stomachal mu-
cous membrane ; g', section of the mucous mem-
brane with the pyloric gastric glands ; v, the
villous surface of the mucous membrane of the
duodenum ; i, section of the same with the in-
testinal glands or crypts of Lieberkiihn ; pp, the
ridge of the pyloric valve, with a section of its
component parts ; mi, deep or circular layer of
muscular fibres : these are seen in the section to
form a part of the pyloric valve ; in e, external
or longitudinal layer of muscular fibres ; s, the serous covering.
The areolar or submucous coat of the stomach is a distinct layer placed
between the muscular and mucous coats, and connected with both : it
consists essentially of a dense filamentous areolar tissue, in which occasional
fat-cells may be found ; and it is the seat of division and passage of the
larger branches of the blood-vessels.
The internal or mucous coat is a smooth, soft, rather thick and pulpy
membrane, which has generally a somewhat pink hue owing to the blood in
its capillary vessels, but which, after it has been well washed, is of a greyish
white or pale straw colour. In some cases, however, it presents this pale
aspect without any previous washing. In infancy the vascular redness is
more marked, the surface having then a rosy hue, but it becomes paler in
childhood, and in aged persons is often of an ash-grey colour. During
digestion its vessels become congested, and when examined in that condition
it is always of a much brighter pink than at other times.
After death a few hours often suffice to change its colour to a dirty brown tint,
mottled and streaked in some cases with dull red lines, corresponding with the course
of the veins. This alteration is owing to the exudation of the colouring matter of
the blood, and is especially met with in old subjects, in whom the mucous membrane
is always thin. In acute inflammation, or after the introduction of irritating sub-
stances or of strong acrid poisons, it becomes of a bright red, either all over or in
spots, patches or streaks of variable sizes. Corrosive poisons, the gastric juice, and
sometimes regurgitating bile, may stain it variously, black, brown, yellow, or green ;
and the effect of chronic inflammation is to leave the membrane of a slate-grey colour.
Independently of all these modifying circumstances connected with the stomach
itself, as was pointed out by Yelloly and others, the colour of the gastric mucous
surface is liable to be influenced by causes of a more general nature. Thus, it has
been found that in cases of obstructed venous circulation, as when death occurs from
hanging or from drowning, and also in certain diseases of the heart, the internal
surface of the stomach is reddened to a greater or less extent ; but the amount of
vascularity may vary from circumstances which are not well understood, and may be
found greatly increased in cases in which none of those now named exist. Trans, of
Med. Chir. Soc., vol. iv. p. 371.
MUCOUS COAT OF THE STOMACH.
835
The gastric mucous membrane is thickest in the pyloric portion of the
stomach, and thinnest in the great cul-de-sac. It always becomes thinner
in old age.
The outer or adherent surface of the mucous membrane is connected with
the muscular coat by means of the intervening submucous layer so loosely
as to allow of considerable movement or displacement. In consequence of
this, and of the great extent and want of elasticity of the mucous membrane
as compared with the other coats, the internal surface of the stomach, when
that organ is in a contracted state, is thrown into numerous convoluted
ridges, rugce, which are produced by the wrinkling of the mucous, together
with the areolar coat, and are entirely obliterated by distension of the
stomach. These folds of the mucous coat are most evident along the great
curvature, and have a general longitudinal direction.
On examining the gastric mucous membrane closely with the aid of a
simple lens, it is seen to be marked throughout, but more plainly towards
the pyloric extremity, with small depressions or cells named alveoli, which
have a polygonal figure, and vary from about -^^th to -j-^th of an inch
across, being larger and more oblong near the pylorus.
Fig. 582. — ENLARGED VIEW OF A SMALL PART OF THE SUR- Fig. 582.
FACE OP THE MUCOUS MEMBRANE OF THE STOMACH (from
Ecker). ia
This specimen shows the shallow alveoli, in each of which
the smaller dark spots indicate the orifices of a variable num-
ber of the gastric glands.
Towards the pyloric region of the stomach, where
the mucous membrane is thicker than elsewhere, the
margins of these alveoli are elevated into pointed
processes or fringes, which may be compared to rudimentary vtili, the
Fig. 583.
Fig. 583. — VERTICAL TRANSVERSE SECTION OP THE
COATS OP A PIG'S STOMACH (from Kolliker). ^-°
a, gastric glands ; 6, muscular layer of the
mucous membrane ; c, submucous or areolar coat ;
d, circular muscular layer ; c} longitudinal mus-
cular layer ; /, serous coat.
perfect forms of those appendages existing
only in the small intestine, and making
their appearance in the duodenum, imme-
diately beyond the pylorus.
At the bottom of the alveoli, and also in
the intervals between them, are seen small
round apertures, which are the mouths of
minute tubes, placed perpendicularly to the
surface, closed at their attached or deep
extremity, which rests on the submucous
areolar tissue, and opening at the other on
the inner surface of the stomach. On mak-
ing a vertical section of the membrane, and
submitting it to microscopic examination,
it is seen to consist almost entirely of these small tubuli, arranged close
to and parallel with each other. Their diameter varies from T^ Dth to ^-g^th of
3 i 2
836
THE STOMACH.
an inch, and their length from ^th to -g^th of an inch. At the cardiac end of
the stomach, where the membrane is thinnest, they are shorter and are simply
tubular ; but, in approaching the pyloric portion, they gradually become longer
Fig. 584. — THE GASTRIC GLANDS OP THE HUMAN STOMACH (magnified).
a, the deep part of a pyloric gastric gland (from Kolliker) ; the cylindrical epithelium
is traceable to the csecal extremities.
6, c, and d, cardiac gastric glands (from Allen Thomson). &, vertical section of a
small portion of the mucous membrane with the glands magnified 30 diameters ; c, deeper
part of one of the glands, magnified 65 diameters, showing a slight division of the tubes,
and a sacculated appearance produced by the large glandular cells within them ; the change
of the prismatic epithelium into spherical gland-cells within the tube is apparent ; d,
cellular elements of the cardiac glands, magnified 250 diameters.
and assume a more complicated form, for, though quite straight near their
orifices, they are curved, clavate, or irregularly sacculated towards their
Fig. 585.
Fig. 585.— PEPTIC GASTRIC GLANDS PROM THE DOG'S
STOMACH, MAGNIFIED (from Frey).
1, longitudinal view ; a, the main duct ; b, one
of the first tubular divisions of the gland ; c, the
single tubes occupied by the gastric or peptic cells ;
d, some of the cells pressed out ; 2, cross section of
the main duct, showing the epithelial lining; 3, cross
section of the simple tubes.
deep or closed extremity. Some are cleft,
first into two or three, and finally into six or
eight tubular branches. These characters
are most perfect near the pylorus. They
exist at all parts of the stomach, even where
the alveoli are indistinct or absent ; they
contain a colourless fluid, with granular
matter, and appear to be the secreting
organs of the gastric mucus and the gastric
juice. The tubuli, generally, are formed of
a simple homogeneous membrane ; fusiform
cells supposed to be muscular lie between
them on their contiguous or attached sur-
GASTRIC GLANDS. 837
faces ; and their inner surface is lined with cells. At the pyloric end of the
stomach these cells appear to be entirely lined with a simple layer of
columnar epithelium ; but in other portions of the organ, only the upper
fourth of the tubuli is occupied by epithelium of that character ; the lower
three-fourths containing finely granular nucleated cells, which are polygonal
or oval in form, are much larger than the columnar, and do not form a
stratum on the surface, but completely fill the cavity : these have been
termed peptic cells. It has been supposed that only those glands which
possess the last-mentioned form of epithelium secrete the gastric juice, and
they have accordingly been named peptic glands, and distinguished from the
mucous glands, in which the epithelium is columnar throughout.
A marked distinction has been made out by various observers between peptic and
mucous glands of the stomach in the lower animals. Not only have their anatomical
characters been found to be different, but likewise their physiological properties, as
it has been ascertained that the gastric secretion only possesses its peculiar solvent
properties when proceeding from those parts of the stomach which contain glands of
the peptic kind. An abrupt separation, however, between the two varieties of gland
does not appear to exist in the human subject. (Henle, Syst. Anat. d. Mensch., vol.
ii., p. 158, where also other works are referred to.)
Lenticular follicles, similar to those of Peyer's glands, are found in the
mucous membrane of the stomach, sometimes studding the greater part of
its surface, and giving occasionally a granular or mammillated appearance to
it. They are found in greater or less numbers all over the stomach, but are
most numerous towards the pylorus. They are best seen in the stomachs
of infants and children. Around the cardiac orifice they assume the charac-
ter of multilocular crypts. They are more frequently found open than shut,
the membrane which covers them being extremely delicate. (Allen
Thomson, in Goodsir's Annals, i. p. 36.)
A distinct but delicate epithelium exists all over the stomach, covering
the margins and floors of the alveoli, and lining the tubuli also. It belongs
for the most part to the columnar variety, alternating in some parts with
the squaruous, which is composed of very minute polygonal scales.
In animals, there is a more or less distinct layer of muscular fibres in intimate
relation with the simple basement-membrane. These fibres are of the plain or un-
striped variety, and are quite distinct from those which constitute the true muscular
coat, being separated from them by the submucous areolar layer.
Vessels and nerves. — The stomach is a highly vascular organ. Its arterial branches,
derived from all three divisions of the coeliac axis, reach the stomach between the
folds of the peritoneum, and form, by anastomosing together, two principal arterial
arches, which are placed along its two curvatures. After ramifying between the
several coats and supplying them with blood, and especially after dividing into very
small vessels in the submucous areolar tunic, the ultimate arterial branches enter the
mucous membrane, and ramifying freely, pass to its surface between the tubuli ; here
they form a plexus of very fine capillaries upon the wells of the tubules ; and from
this plexus larger vessels pass into a coarser capillary network upon the hexagonal
borders of the alveoli. The veins, corresponding with the arteries, arise from the
latter network (Brinton, "Stomach and Intestine " in Cyclop, of Anat.), and, after
forming a wide venous plexus in the submucous tissue, return the residual blood
into the splenic and superior mesenteric veins, and also directly into the vena portae.
By the breaking up of the arteries into capillaries on the walls of the glands, these
are furnished with pure blood for the elaboration of their secretion ; while it is the
blood from which that secretion has been drawn which passes on to the capillaries of
the free surface, and has added to it whatever materials may be taken into the cir-
culation from the contents of the stomach.
838 THE STOMACH.— THE INTESTINE.
The absorbents are very numerous; arising from a very fine superficial plexus
immediately underlying the tubular glands, they form a coarser deeply situated net-
work, between the areolar and muscular coats ; the vessels proceeding from this
network pierce the muscular coats, then follow the direction of the blood-vessels
beneath the peritoneal investment, and traverse lymphatic glands found along the
two curvatures of the stomach. No trace of lymphatics has been found between the
tubuli, therefore the whole depth of the secreting structure intervenes between the
layer of lymphatics and the contents of the stomach, whereas capillary blood-vessels
are distributed close to the surface ; an arrangement which seems favourable for the
interchange of material between the contents of the stomach and those of the blood-
vessels rather than of the lymphatics.
The nerves, which are large, consist of the terminal branches of the two pneumo-
gastric nerves, belonging to the cerebro-spinal system, and of offsets from the sympa-
thetic system, derived from the solar plexus. Numerous small ganglia have been
found by Remak and others on both the pneumo-gastric and sympathetic twigs. The
nerves may be traced through the submucous coat, but no farther, as they then lose
their tubular character, and cannot be distinguished from other tissues. (Kolliker.)
The left pneumo-gastric nerve descends on the front, and the right upon the back of
the stomach.
The pylorus. — While there is no special apparatus at the cardiac orifice of
the stomach for closing the passage from the oesophagus, the opening at the
pyloric end, leading from the stomach into the duodenum, is provided with
a sphincter muscle. On looking into the pyloric end of the stomach, the
mucous membrane is seen projecting in the form of a circular fold, called
the pylorus, leaving a correspondingly narrow opening. Within this fold
are circular muscular fibres, belonging to the general system of circular
fibres of the alimentary canal, which are here accumulated in the form of
a strong band, whilst the longitudinal muscular fibres and the peritoneal
coat pass over the pyloric fold to the duodenum, and do not enter into its
formation. Externally the pylorus may be easily felt, like a thickened
ring, at the right end of the stomach. Internally its opening is usually
circular, and less than half an inch across, so that it is the narrowest part
of the whole alimentary canal. (See figures 581 and 586.)
Occasionally the orifice is oval, and it is often placed a little to one side. Some-
times the circular rim is imperfect, and there are found instead two crescentic folds,
placed one above and the other below the passage (Huschke) ; and, lastly, there is
occasionally but one such crescentic fold.
THE SMALL INTESTINE.
The small intestine reaches from the pylorus to the ileo-csecal valve, at
which it opens into the large intestine. It consists of a convoluted tube,
measuring on an average about twenty feet in length in the healthy adult,
and becoming gradually slightly narrower from its upper to its lower end.
Its numerous convolutions occupy the middle regions of the abdomen, and
are surrounded by the large intestine. They are connected with the back
of the abdominal cavity, and are held in their position by a covering and
fold of the peritoneum, named the mesentery, and by numerous blood-
vessels and nerves.
The small intestine is arbitrarily divided into three portions, which have
received different names ; the first ten or twelve inches immediately suc-
ceeding to the stomach, and comprehending the widest and most fixed part
of the tube, being called the duodenum, the upper two-fifths of the remainder
being named the jejunum, and the lower three-fifths the ileum. There
THE DUODENUM.
839
are no distinct lines of demarcation between these three parts, but there
are certain peculiarities of connection and certain differences of internal
structure to be observed in comparing the upper and lower ends of the
entire tube, which will be pointed out after it has been described as a
whole.
DUODENUM. — This is the shortest and widest part of the small intes-
tine. In length it measures 10 or 12 inches, or nearly tha breadth of
twelve fingers ; hence its name.
It is the widest part of the small intestine, varying in diameter between
an inch and a half and two inches. In its course it describes a single
large curve somewhat resembling a horse-shoe, the convexity of which is
turned towards the right, whilst the concavity embraces the head of the
pancreas.
It has no mesentery, and is covered only partially by the peritoneum.
Its muscular coat is comparatively thick, and its mucous membrane towards
Fig. 586.
Fig. 586. — VIEW OF THE DUODENUM FROM
BEFORE (slightly altered from Luschka). \
12, the twelfth dorsal vertebra and rib ; 1,
3, 4, 5, transverse processes of the first, third,
fourth, and fifth left lumbar vertebrae ; 2,
that of the second on the right side ; a, a,
the abdominal aorta above the coeliac axis and
near the bifurcation ; m, superior mesenteric
artery ; v, v, the vena cava above the renal
veins and near the bifurcation ; p, placed on
the first part of the duodenum, points to the
pyloric valve seen from the side next the
stomach, of which a small part is left con-
nected with the intestine ; d, on the descend-
ing or second part of the duodenum, indicates
the termination of the common bile-duct and
the pancreatic duct ; d\ the third or oblique
part of the duodenum ; j, the commencement
of the jejunum.
the pylorus is the seat of the com-
pound glands of Brunner, to be sub-
sequently described. The common bile-duct and the pancreatic duct open
into this part of the intestinal canal.
Three portions of the duodenum, differing from each other in their course
and connections, are separately described by anatomists ; viz., the superior,
descending, and transverse portions.
The first, or superior portion, which is between two and three inches long,
commences at the pylorus, and passing upwards, backwards, and to the right
side, reaches as far as beneath the neck of the gall-bladder, where the
intestine bends suddenly downwards. The first portion of the duodenum is
for the most part free, and invested both in front and behind by the peri-
toneum. Above, and in front of it, are the liver and gall-bladder, and it is
commonly found stained by the exudation of bile from the latter a few
hours after death. Behind it is the hepatic duct, with the blood-vessels
passing up to the liver.
The second, or descending portion, commencing at the bend below the
neck of the gall-bladder passes vertically downwards in front of the right
kidney, as low as the second or third lumbar vertebra, where the bowel
turns across to the left to form the third portion. This part of the
840 THE INTESTINE.
duodenum is invested by the peritoneum on its anterior surface only, —
the posterior surface being connected to the right kidney and the verte-
bral column by areolar tissue. In front is the transverse colon and meso-
colon, the upper layer of which is continuous with the peritoneal covering
of the duodenum. To the left is the head of the pancreas, which adapis
itself to the shape of the intestine on that side. The common bile-duct
descends behind the left border of this part of the duodenum, and, to-
gether with the pancreatic duct, which accompanies it for a short distance,
perforates the coats of the intestine obliquely near the lower part of its left
or concave border. In the interior of this part of the intestine the val-
vulse conniventes appear numerously ; and an eminence or papilla found
about four inches below the pylorus, on the inner and back part of tho
intestine, marks the situation of the common orifice of the biliary and pan-
creatic ducts.
The third or transverse or oblique portion, somewhat the longest and nar-
rowest, beginning on the right of the third lumbar vertebra, crosses in front
of the second obliquely from right to left, and, continuing to ascend obliquely
for an inch or more, ends in the jejunum at the left side of the vertebral
column. It is placed immediately behind the root of the transverse meso-
colon, and the commencement of the mesentery, as has been already de-
scribed, and has the V( na cava inferior and the aorta behind it. At its
termination it forms an abrupt angle with the commencement of the jeju-
num. This is due to its being maintained, at that point, in its position, by
a strong fibrous band descending from the left eras of the diaphragm and
the tissue round the coeliac axis. According to Treitz, muscular fibres
come from both these sources to this part of the duodenum. In subjects
in which the intestines are large and dilated, the curve of the duodenum
may descend to the level of the iliac crest, but, owing to the support given
by the baud alluded to, its terminal extremity maintains a uniform position.
Close to this point the superior mesenteric vessels pass from beneath the
pancreas to enter the mesentery on the surface of the duodenum.
JEJUNUM AND ILEUM. — The jejunum, originally so called from its having
been supposed to be empty after death, follows the duodenum, and in-
cludes the upper two-fifths of the remainder of the small intestine, while
the succeeding three-fifths constitute the ileum, so named from its nume-
rous coils or convolutions. Both the jejunum and the ileum are attached
and supported by the mesentery. The convolutions of the jejunum are
situated in part of the umbilical and left iliac regions of the abdomen ;
while the ileum occupies part of the umbilical and right iliac regions,
together with the hypogastric, and descends into the pelvis, from which its
lower end, supported by the mesentery, which is heie very short, ascends
obliquely to the right and somewhat backwards, over the corresponding
psoas muscle, and ends in the right iliac fossa, by opening into the inner
side of the commencement of the large intestine. There is no defined
limit between the jejunum and the ileum, but the character of the intes-
tine gradually changes from its upper to its lower end, so that portions
of the two intestines, remote from each other, present certain well-
marked differences of structure, which may be here enumerated. Thus,
the jejunum is wider, and its coats are thicker ; it is more vascular, and
therefore it has a deeper colour ; its valvulse conniventes are long, wide,
and numerous ; its villi are well developed ; and the patches of Peyer's
glands are smaller, less frequent, and sometimes confined to its lower
part. The ileum, on the other hand, is narrower ; its coats are thin-
STRUCTURE OF THE SMALL IXTESTIXE. 841
ner and paler ; the valvulse conniventes are small, and gradually dis-
appear towards its lower end ; the villi are shorter ; and the groups of
Peyer's glands are larger and more numerous. The diameter of the je-
junum is about one inch and a half, that of the ileum about one inch
and a quarter. A given length of the jejunum weighs more than the
same of the ileum.
At a point in the lower part of the ileum it is not very uncommon to find a cul-de-
sac or diver ticulum given off from the main tube. The origin of these diverticula is
explained by reference to the history of development, from which it appears that they
arise in connection with the ductus vitello-intestinalis, uniting the intestine with
the umbilical vesicle. They are not to be confounded with hernial protrusions of
the mucous membrane, which may occur at any point. (See Meckel's Handbook of
Anatomy, French edition, vol. ii. p. 431.)
Structure of the Small Intestine.
Structure. — The walls of the small intestine, like those of the stomach,
are composed of four coats, viz., the serous, muscular, areolar, and mucous.
The external or serous coat, derived from the peritoneum, almost en-
tirely surrounds the intestinal tube in the whole extent of the jejunum
and ileum, leaving only a narrow interval along one border of the intes-
tine, where it is reflected from it and becomes continuous with the two
layers of the peritoneal duplicature named the mesentery. The line at
which this reflexion takes place is named the attached or mesenteric border
of the intestine. The opposite border and sides of the tube, which are
covered by the peritoneum, are quite free and movable upon the adjacent
parts. The upper part, however, of the small intestine, named the duode-
num, is but partially covered by the peritoneum, as has been already more
particularly described.
The muscular coat consists of two layers of fibres ; an outer longitudinal,
and an inner or circular set. The longitudinal fibres constitute an entire
but comparatively thin layer, and are most obvious along the free border
of the intestine. The circular layer is much thicker and more distinct ; its
fibres are placed closely together, and run in a circular direction around the
bowel, but it does not appear that they individually form perfect rings.
This muscular tunic becomes gradually thinner towards the lower part
of the small intestine. It is pale in colour, and is composed of plain mus-
cular fibres. The progressive contraction of these fibres, commencing in
any part of the intestine, and advancing in a downward direction, produces
the peculiar vermicular or peristaltic movement by which the digestive mass
is forced onwards through the canal. In this movement the circular fibres
are mainly concerned ; but the longitudinal fibres also aid in it ; and those
found along the free border of the intestine may have the effect of straighten-
ing or unfolding, as it were, its successive convolutions.
The areolar or submucous coat of the small intestine is a tolerably distinct
and whitish layer, of a loose texture, which is connected more firmly with
the mucous than with the muscular coat, between which two it is placed.
By turning a portion of the intestine inside out, and then blowing forcibly
into the cavity, the areolar tunic may be inflated, the air being driven into
its areolar tissue, through the part at which the peritoneal investment is
wanting. It supports the mucous membrane, and forms a layer of loose
substance in which the vessels divide and subdivide into smaller branches,
preparatory to entering the mucous tissue. It consists of filamentous areolar
tissue, mixed with fine elastic fibres.
812 THE INTESTINE.
The internal or mucous coat is characterised by presenting all over its
inner surface a finely flocculeiit or shaggy appearance, like the pile upon
velvet, owing to its being covered with multitudes of minute processes,
named -villi ; hence it is also named the villous coat. It is one of the
most vascular membranes in the whole body, and it is naturally of a red-
dish colour in the upper part of the small intestine, but becomes paler, and
at the same time thinner towards the lower end. The mucous tissue con-
tains beneath its basement membrane, a thin muscular layer, demonstrated
easily in animals, but scarcely recognisable in man. It presents for con-
sideration, 1, the large folds called valvulce conniventes ; 2, the villi and
epithelium ; 3, the glands.
1. Valvulce Conniventes. — The folds and wrinkles found upon the inner
surface of the oesophagus and stomach may be completely obliterated by full
distension of those parts of the alimentary canal. In the lining membrane
of the small intestine, however, there exist, besides such effaceable folds,
other permanent ones, which cannot be obliterated, even when the tube is
forcibly distended. These permanent folds are the valvulce conniventest or
valves of Kerkring. They are crescentic projections of the mucous mem-
brane, placed transversely to the course of the bowel, each of them reaching
about one-half or two-thirds of the distance round the interior of the tube,
and they follow closely one upon another along the intestine.
The largest of these valves are about two and a half inches long and one-
third of an inch wide at the middle or broadest part; but the greater number
are under these dimensions. Large and small valves are often found to alter-
nate with each other. Some of them are bifurcated at one end, and others
terminate abruptly, appearing as if suddenly cut off. Each valve consists of
a fold of the mucous membrane, that is, of two layers placed back to back,
united together by the submucous or areolar tissue. They contain no part
of the circular and longitudinal muscular coats. Being extensions of the
mucous membrane, they serve to increase the absorbent surface to which the
food is exposed, and at the same time they contribute to delay its passage
along the intestine.
There are no valvulse conniventes quite at the commencement of the
duodenum ; about an inch or somewhat more from the pylorus they begin
to appear ; beyond the point at which the bile and pancreatic juice are
poured into the duodenum they are very large, regularly crescentic in form,
and placed so near to each other that the intervals between them are not
greater than the breadth of one of the valves : they continue thus through
the rest of the duodenum and along the upper half of the jejunum ; below
that point they begin to get smaller and farther apart ; and finally, towards
the middle of the ileum, having gradually become more and more irregular
and indistinct, sometimes even acquiring a very oblique direction, they alto-
gether disappear.
2. Villi. — The villi, peculiar to the small intestine, and giving to its
internal surface the velvety or villous appearance already spoken of, are
small, elongated, and highly vascular processes, which are found situated
closely together on every part of the mucous membrane, over the valvulao
conniventes, as well as between them. They are best displayed by placing
a piece of intestine, well cleansed from its mucus, under water, and examin-
ing it with a simple lens. The prevalent form of the villi is that of minute,
flattened, bell-shaped membranous processes ; others are conical or cylindrical,
or even clubbed, or filiform at the free extremity. A few are compound as
if two or three villi were connected together at their base.
YILLI OF THE MUCOUS MEMBRANE.
843
Their length varies from |th to ird of a line, or even more ; and the
broad flattened kinds are about ^-th or Jth of a line wide, and ^\jth or -^th
of a line thick. They are largest and most numerous in the duodenum'and
jejunum, and become gradually shorter, smaller, and fewer in number in the
ileum. In the upper part of the small intestine Krause has estimated their
number at from 50 to 90 in a square line; and in the lower part at from 40
to 70 in the same space : he calculates their total number to be at least four
millions.
The structure of the villi is complicated : each consists of a prolongation
of the proper mucous layer, covered by epithelium and enclosing blood-ves-
Fig. 587.— MAG-
NIFIED VIEW OP
THE BLOOD-VES-
SELS OP THE IN-
TESTINAL VILLI.
The drawing was
taken from a pre-
paration injected by
Lieberkiihn, and
shows in each villus
a small artery and
vein with the in-
termediate capil-
lary network.
Fig.
sels, one or more lacteal vessels, and fine muscular fibres, with a greater or
less number of small granular corpuscles and fat-globules, of various sizes.
Fig. 588.— INJECTED LACTEAL
VESSELS IN THE VILLI OP THE
HUMAN INTESTINE.
A, two villi in which the lacteals
are represented as filled with white
substance and the blood-vessels
with dark (from Teichinann) — ^ :
a, 6, the lacteal vessels, single in
one villus and double with cross
loops in the other ; e, the hori-
zontal lacteal vessels with which
those of the villi communicate ;
d, the blood-vessels, consisting of
small arteries and veins with
capillary network between.
B, injected lacteal (shaded dark)
in a villus, showing an example
not very common of a looped net-
work a, which is connected by a
single vessel with the horizontal
lacteal vessel 6 : the preparation
was made from the intestine of
a young man who died suddenly
while digestion was going on (from
W. Krause). ^
Fig. 588.
A.
Nerves have not yet been demonstrated in the villi, though they are probably
not wanting. Each villus receives one or more small arteiial twigs, which
844
THE INTESTINE.
divide, and form upon its surface, beneath the epithelium and limiting
membrane, a fine capillary network, from which the blood is returned for the
most part by a single vein.
The lacteal lies iti the centre of the villus, and is in the smaller villi usually
a single vessel, with a somewhat expanded extremity, and of considerably
larger diameter than the capillaries of the blood-vessels around. According
to the observations of Teichmann, there are never more than two intercom-
municating lacteals in a single villus in the human subject; but both he and
Frey find a copious network of them in the villi of the sheep. Considerable
difference of opinion exists as to the nature of the wall of the lacteal in the
villus, and even as to whether or not any wall exists, and this point must
be considered as still undetermined. The epithelium of the villi is of the
columnar kind ; the cell-wall is delicate, and the nucleus distinct. The
nature of both the free and the attached extremities of the cells is involved
Fig. 589.
cut irregularly ; ?', the submucous layer.
A, cross section of three tubular glands more highly magnified.
Fig. 589.— VERTICAL SECTION OF
THE INTESTINAL MDCOUS MEM-
BRANE OF THE RABBIT (slightly
altered from Frey). -^
Two villi are represented, in one
of which the dilated lacteal alone is
represented, in the other the blood-
vessels and lacteal are both shown
injected, the lacteal vhite, the
blood-vessels dark : the section is
carried through the tubular glands
into the submucous tissue : a, the
lacteal vessels of the villi ; a', below
the glands, the horizontal lacteal,
which they join ; 6, the capillary
blood- vessels shown only in one of
the villi ; c, a small artery ; d, a
vein ; e, the epithelium covering
the villi ; /, the substance of the
villi, piesenting interstices which
contain lymph-cells ; g, tubular
glands or crypts of Lieberkiihn,
some divided in the middle, others
in some doubt. At the free extremity, they present to view a thick layer
of substance with vertical striee, which, on treatment with water, swells out
and loses its striated appearance. This layer was first recognised by Kol-
liker and by Funke, who both consider the striae to be minute perforating
canals ; while Brettauer and Steinach, and likewise Henle, maintain that
they are rods comparable with cilia. Briicke, previous to the discovery of
the striated body, advanced the opinion that the epithelium- cells were alto-
gether open at their free extremities, and that each communicated likewise
with the interior of the villus by a foramen at the deep extremity. Brettauer
and Steinach support Brlicke's view, in respect that they consider the striated
body as continuous with the cell-contents, and not with the cell-wall. With
regard to the deep extremities of the epithelial cells, Heidenhain believes
that he has observed them prolonged into fine threads, which communicate
with branches of anastomosing connective tissue-corpuscles, and considers
EPITHELIUM OF THE VILLI. 845
that, by means of deep branches of these anastomosing cells opening into the
cavity of the lacteal, a channel of communication is established between the
lacteal and the surface of the villus. This view has met with some accept-
ance from its seeming to offer an explanation of the mode in which particles
of oil are conveyed from the intestines into the lacteals ; but it cannot
Fig. 590.
QjO2n* e m
W n
Fig. 590.— EPITHELIUM OF THE INTESTINAL VILLUS OF A RABBIT (from Kolliker).
A, ^ ; B, aft
A, series of the cylindrical epithelial cells separated from a villus ; a limiting or cuti-
cular membrane or border is seen passing over the free ends of the cells.
B, some of the same cells treated with water ; in 1 and 2, and at a, in the left hand
series of cells, the striated or porous border is seen ; and at b, in the latter, pellucid drops
of mucus which have escaped from the cells.
at present be considered as satisfactorily established. The muscular tissue
within the villi was first discovered by Briicke : it consists of a thin stratum
of smooth fibres disposed longitudinally round the commencement of the
lacteals. Although not always discernible in man, these fibres are distinct
in animals ; and in them, on being stimulated, they produce, according to
Briicke, a very obvious retraction of the villi.
During digestion, the epithelial cells become turbid with minute oil drops
in their interior, which obscure their nuclei. The tissue of the villus itself
becomes turbid in like manner ; and clear globules may also be observed,
both in the epithelial cells and deeper tissue, which, however, there seems
reason to believe, are formed by the running together of smaller particles
after death. Kolliker and Donders have both observed minute particles of
oil in their passage through the striated body.
A full bibliography, on the subject of the villi, is given by Teichmann in his work
"das Saugadersystem," (1861), pp. 77 et seq. ; and the questions at issue are fully
discussed in Kb'lliker's Gewebelehre, 4th edition, and Henle's System. Anatomic. See
also Frey, in Zeitsch. f. Wissensch. Zoologie, vol. xiii. Heidenhain's paper is in Mole-
schott s Untersuchungen z. Naturlehre, vol. iv. Peculiar epithelial cells with deeply
hollowed cup-shaped extremities, have been pointed out by Henle, interspersed
among the others. It is yet uncertain whether they are a distinct kind of cell, or
only a peculiar condition of the ordinary sort.
3. Glands. — The glandular structures found in the mucous coat of the
small intestine are the crypts or follicles of Lieberkiihn, the solitary gland?,
the patches of Peyer's glands, and Brunner's glands, the last being peculiar
to the duodenum.
The crypts of Lieberkiihn, the smallest of these glandular structures, are
found in every part of the small intestine, between the villi, and surrounding
the larger glands. They consist of minute tubes, closed at their attached
extremity, and placed more or less perpendicularly to the surface, upon
846
THE INTESTINE.
which they open by small orifices. They appear to be analogous to the
tubuli of the stomach, but they are placed farther apart from each other, and
are sometimes bulged inferiorly, but are hardly ever divided. Similar
tubules also occupy the whole mucous membrane of the large intestine.
The crypts of Lieberkiihn vary in length from the ^th to the /^th of a
line, and their diameter is about ^th of a line. The walls of the tubes are
thin, and lined with a columnar epithelium : their contents are fluid and
transparent, with granules interspersed, and they never contain fat. These
crypts are sometimes filled with a whitish substance, which most probably
consists chiefly of desquamated epithelium and mucus.
The agminated glands, or glands of Peyer (who discovered and described
them in 1677), are found in groups or patches, having an oblong figure, and
Fig. 591 A. Fig. 591 A.— PATCH OP PETER'S
GLANDS IN THE ILEUM.
This figure represents, some-
what diagraminatically, and of
the natural size, a patch, of
Peyer's glands from near the
middle of the ileum of a young
subject : in the lower half of the
figure the mucous membraneand
the glands have been removed by
dissection, showing the impres-
sion left by the patch of glands
by the condensation of the sub-
mucous tissue : the piece of
intestine having been opened
along its meseuteric border,
the blood-vessels are seen ad-
vancing from the separated
margins towards the centre.
varying from half an inch
to two or even four inches
in length, and being about
half an inch, or rather
more, in width. These
patches are placed length-
ways in the intestine at that part of the tube most distant from the mesen-
tery ; and hence, to obtain the best view of them, the bowel should be
opened by an incision along its attached border.
The patches of Peyer's glands consist of groups of small, round, flattened
vesicles or capsules composed of a tolerably thick and firm wall of connective
tissue, usually filled with a whitish or rather greyish semi-fluid matter, con-
sisting of round nucleated cells and free nuclei, and situated beneath the
mucous membrane, the surface of which is depressed into little shallow pits,
at or rather under the bottom of which the capsules are placed. The inter-
mediate surface of the membrane is beset with villi and Lieberktihn's crypts :
the villi are also sometimes found even over the capsules, and the crypts are
collected in circles around the capsules, but do not communicate with them.
Opposite to the patches of Peyer's glands, the mucous and areolar coats of
the intestine adhere more closely together than elsewhere, so that in those
situations it is impossible to inflate the areolar coat. Fine blood-vessels are
distributed abundantly on the walls of the capsules, and give off still finer
capillary branches, which, supported by a delicate network of connective
PEYEE'S GLANDS.
847
tissue, spread through the cavity of each capsule among its semifluid contents,
and are disposed principally in lines converging to the centre. In some
subjects these small capsules are found almost empty, and then they are
Fig. 591 B.
Fig. 591 B. — ENLARGED VIEW OF A
PART OF A PATCH OF PETER'S GLANDS
(from Boehm). V
The shaded part of the figure shows
the surface of the intestinal mucous
membrane in the vicinity of the patch
occupied by villi, and between them the
orifices of the crypts of Lieberkiihn ; the
lighter part of the figure, in which about
a dozen of Peyer's vesicles may be seen,
is also beset with villi, and in this part
the crypts of Lieberkiihn are arranged
chiefly in circles round the vesicles.
difficult of detection. They are
usually entirely closed ; but the
elder Krause observed 'that in the
pig they were occasionally open,
and a similar observation was
made by Allen Thomson, not only
in the pig, but in the human intestine also.
The lacteal plexuses, which are abundant in the whole extent of the in-
testine, are especially rich and composed of wide vessels, where they
EDHKJH -j
Fig. 592.
Fig. 592 — TRANSVERSE SEC-
TION OF INJECTED PETER'S
GLANDS (from Kolliker).
The drawing was taken
from a preparation made by
Frey : it represents the fine
capillary network spreading
from the surrounding blood-
vessels into the interior of
three Peyer's capsules from
the intestine of the rabbit.
surround the closed fol-
licles, so closely indeed
that these may be said to
be imbedded in them ;
but the lacteuls do not
penetrate the capsules as
the capillary blood-ves-
sels do.
It was formerly pre-
sumed without question
that Peyer's and the other
closed follicles in the alimentary tract constituted a peculiar capsularform of secreting
glands ; but since the discovery of capillaries in their interior, and of the rich supply of
absorbents around them, it has been supposed that they might be more immediately
connected with the lymphatic system. This, however, is by no means proved ; for,
although the interior of the capsules can no longer be compared with the cavities of
848
THE INTESTINE.
open glands, there is not sufficient evidence to show whether their contents pass
into the intestinal tube or into the lacteals, from which they are as completely sepa-
rated by intervening texture. The facts which have been ascertained as to their
minute structure, and the nature of their contents, seem to bring them rather under
the description of vascular glands. It may farther be stated as a point of analogy
between them and those structures, that the glands of Peyer belong chiefly to youth.
After middle life they become more or less flaccid and empty, and have generally
completely disappeared in advanced age.
Fig. 593.
Fig. 593.— VERTICAL SECTION OP A PORTION OF A PATCH OF PETER'S GLANDS, WITH
THE LACTEAL VESSELS INJECTED (from Frey). ^
The specimen from which the drawing was made was obtained from the body of a man of
twenty years of age who died suddenly from an injury, and is from the lower part of the
ileum ; the epithelium, not represented in the original, is introduced diagram matically in
one part : a, villi, with their lacteals left white ; 6, some of the tubular glands ; c, the
muscular layer of the mucous membrane ; d, the cupola or projecting part of Peyer's
vesicles ; e, their central cavities or substance ; /, the reticulated lacteal vessels occupying
the "lymphoid" tissue between the vesicles, joined above by the lacteals from the villi
and mucous surface, and passing below into g, the reticulated lacteals under the vesicles
of Peyer, which pass into g', the larger lacteals of the submucous layer i.
The observations of Frey and His have further shown that in the intervals between
the glands of Peyer and those of Lieberkiihn, and also in the substance of the villi,
the interstices of the retiform tissue (see Histology, p. Ixxix), are everywhere occupied
by granular cells of the size and appearance of lymph-cells, and very similar to those
contained in the capsules of Peyer's glands.
In all, from twenty to thirty of these oblong patches may in general be
found ; but in young persons dying in health, as many as forty-five have
been observed. They are larger and placed at shorter distances from each
other, in the lower part of the ileum ; but in the upper portion of that
intestine and in the lower end of the jejunum, the patches occur less and
less frequently, become smaller, and are of a nearly circular form ; they
may, however, be discovered occasionally in the lower portion of the duo-
denum.
SOLITARY GLAXDS.— BRUNXER'S GLAXDS.
849
Still smaller irregularly shaped clusters of these capsules are found scat-
tered throughout the intestine, and may be regarded as transitions to the
next form of glands named solitary.
Fig. 594.
Fig. 594. — LYMPHOID OR RETIFORM TISSUE OF
THE INTESTINAL Mucous MEMBRANE OF THE
SHEEP (from Frey). ±p
The figure represents a cross section of a
small fragment of the mucous membrane, in-
cluding one entire crypt of Lieberkiihn and
parts of several others : a, cavity of the
tubular glands or crypts ; J, one of the lining
epithelial cells ; c, the lymphoid or retiform
spaces, of which some are empty, and others
occupied by lymph-cells, as at d.
The solitary glands (glandule soli-
tarise) are soft, white, rounded, and
slightly prominent bodies, about the
size of a millet-seed, which are found
scattered over the mucous membrane in every part of the small intestine.
They are found on the mesenteric as well as on the free border, between and
upon the valvulse conniventes, and are rather more numerous in the lower
portion of the bowel. These small glands have no orifice, but consist of
closed vesicles or capsules, exactly resembling those forming the clusters of
Peyer's glands, having rather thick but easily destructible walls, and usually
Fig. 595.
Fig. 595. — SOLITARY VESICULAR GLAND OF THE SMALL INTES-
TINE (from Ecehm). i?
The lighter part of the figure represents the elevation pro-
duced by the gland ; on this a few villi are seen, and on the
surrounding surface of the mucous membrane numerous villi
and crypts of Lieberkiihn.
containing in their interior an opaque, semifluid sub-
stance, which abounds in cells and fine granules. The
free surface of the capsules, which is slightly elevated
when they are full, is beset with the intestinal villi ;
and, placed around them very irregularly, are seen the open mouths of the
crypts of Lieberktihn.
Brunner's glands are small rounded compound glands, first pointed out by
Brunner, which exist in the duodenum, where they are most numerous at
the upper end, in general occupying thickly a space of some inches in
extent from the pylorus. According to Huschke, a few of them are also
found quite at the commencement of the jejunum. They are imbedded in
the areolar tunic, and may be exposed by dissecting off the muscular coat
from the outside of the intestine. They are true compound racemose
glands, consisting of minute lobules, and containing branched ducts, which
open upon the inner surface of the intestine. Their secretion is an alkaline
mucus, in which there are no formed elements ; and it has no digestive
action upon coagulated albumen. (Kolliker.)
Vessels and Nerves. — The branches of the mesenteric artery, having reached the
attached border of the intestine, pass round its sides, dividing into numerous rami-
fications and frequently anastomosing at its free border. Most of the larger branches
3 K
850
THE INTESTINE.
run immediately beneath the serous tunic; many pierce the muscular coat, sup-
plying it with vessels as they pass, and having entered the submucous areolar
Fig. 596. Fig. 596. — ENLARGED VIEW
OF ONE OF BRUNNER'S
GLANDS FROM THE HUMAN
DUODENUM (from Frey).
The main duct is seen
superiorly ; its branches are
elsewhere hidden by the
bunches of opaque glandular
vesicles.
layer, ramify in it, so as to
form a close network, from
which still smaller vessels
pass on into the mucous
coat, and terminate in the
capillary network of the
folds, villi, and glands of
that membrane, which is
the most vascular of all
the intestinal tissues. The
fine capillaries of the mus-
cular coat are arranged in two layers of oblong meshes, which accompany and cor-
respond in direction with the longitudinal and circular muscular fibres. The veins
accompany the arteries.
The absorbents of the intestine may be conveniently distinguished as those of the
mucous membrane and those of the muscular walls. Those of the mucous mem-
brane form a copious plexus which pervades both the mucous and submucous layers,
the largest vessels being those which are in the latter layer ; but there is not, in the
human subject at least, the same distinct division into two strata which has been
found in the stomach (Teichmann). With regard to the absorbents of the muscular
walls, it has been stated in a former part of this work (p. 491) that, according to the
concurrent accounts of the various investigators of this subject, the absorbents of the
intestine are in two strata, viz., those of the submucous layer already mentioned,
and a subserous set, following principally a longitudinal direction beneath the peri-
toneum, and having only an interrupted communication with the other through
intervening trunks ; but more recently, a paper by Auerbach has appeared, in which
it is stated as the result of transparent injections, that the only truly subperitoneal
plexus which exists is confined to a strip in the immediate neighbourhood of the
mesentery ; that the longitudinal plexus seen by previous observers is really situated
between the circular and longitudinal muscular coats ; and that, besides this, there
are likewise copious and close minute capillary plexuses, threading the whole thick-
ness of the muscular walls, in complete continuity with the mucous absorbents, and
throwing their contents into those larger vessels the position of which had been mis-
understood. To the whole of this series of absorbents Auerbach gives the name of
" interlaminar plexus." (Virchow's Archiv., vol. xxxiii., p. 340.)
The nerves of the small intestine are chiefly derived from the superior mesenteric
plexus (see p. 702). This plexus is formed superiorly by nervous branches, of which
those in the middle come from the coeliac plexus, and the lateral ones proceed directly
from the semilunar ganglion. The plexus and plexiform branches into which it
divides cling at first very closely to the larger divisions of the superior mesenteric
artery, especially on their anterior surface, and, dividing similarly with the ramifi-
cations of the arteries, the branches of the nerves, retaining still a wide plexiform
arrangement, pass onwards to the different parts of the intestine between the two
folds of the mesentery, and finally, separating somewhat from the blood-vessels, reach
the intestine in very numerous branches.
In regard to the nervous distribution in the coats of the intestine, two recent dis-
coveries of considerable interest have been made. One of them, for which we are
indebted to Auerbach, consists in the observation of a peculiar nervous plexus, rich
INTESTINAL NERVOUS PLEXUSES.
851
in ganglion-cells, which is situated between the circular and longitudinal muscular
fibres of the intestine, and to which he has therefore given the name of "plexus
myentericus." For the other observation we are indebted to Meissner, who has dis-
Fig. 597 A.
Fig. 597 B.
Fig. 597 A. — NERVOUS PLEXUS OP AUERBACH, FROM THE MUSCULAR COAT OP A
CHILD'S INTESTINE (from Kolliker). -^
The drawing represents three perforated ganglionic masses united by several nervous
cords, of which the thickest is also perforated, forming the "plexus myenteiicus."
Fig. 597 B.— SMALL PORTION OF MEISSNER'S SUBMUCOUS NERVOUS PLEXUS FROM THE
INTESTINE OP A CHILD (from Kolliker). ^-°
Two ganglia are represented, of which the cells are seen spreading into the nerve-twigs
connected with the ganglia : the fusiform particles in the nerve-twigs are small connective
tissue corpuscles.
covered a second richly gangliated plexus of nerves situated in the submucous layer,
and which is found to communicate freely with the plexus myentericus of Auerbach
by means of the larger branches. Both plexuses extend through the whole length of
the intestine, from the pylorus to the anus. (Kolliker, Op. cit., pp. 430 and 432.)
THE LARGE INTESTINE.
The large intestine extends from the termination of the ileum to the anus.
It is divided into the csecum (including the vermiform appendix), the colon,
and the rectum ; and the colon is again subdivided, according to its direction,
into four parts, called the ascending, transverse, and descending colon, and
the sigmoid flexure.
The length of the large intestine is usually about five or six feet ; being
about one-fifth of the whole length of the intestinal canal. Its diameter,
3 K 2
852 THE INTESTINE.
which greatly exceeds that of the small intestine, varies at different points
from two inches and a half to about one inch and a half. It diminishes
gradually from its commencement at the csecum to its termination at the
anus; excepting that there is a well-marked dilatation of the rectum just
above its lower end.
In outward form, the greater part of the large intestine differs remarkably
from the small intestine ; for, instead of constituting an even cylindrical
tube, its surface is thrown into numerous sacculi, marked off from each other
by intervening constrictions, and arranged in three longitudinal rows, sepa-
rated by three strong flat bands of longitudinal muscular fibres. This saccu-
lated structure is not found in the rectum.
For the sake of convenience, the description of the rectum will be reserved
till that of the rest of the great intestine is completed.
The C^CUM. The intestinum csecum, or caput caecum coli, is that part
of the large intestine which is situated below the entrance of the ileum. Its
length is about two inches and a half, and its diameter nearly the same : it
is the widest part of the large intestine.
The csecum is situated in the right iliac fossa, immediately behind the an-
terior wall of the abdomen. It is covered by the peritoneum in front, below,
and at the sides : but behind it is usually destitute of peritoneal covering,
and is attached by areolar tissue to the fascia covering the right iliacus
muscle. In this case the csecum is comparatively fixed ; but in other in-
stances the peritoneum surrounds it almost entirely, and forms a duplicature
behind it, called meso-cczcum.
Proceeding from the inner and back part of the csecum, at its lower end,
is a narrow, round, and tapering portion of the intestine, named the appendix
cceci, or appendix vermiformis. The width of this process is usually about
that of a large quill or rather more, and its length varies from three to six
inches, these dimensions differing much in different cases. Its general direc-
tion is upwards and inwards behind the csecum ; and after describing a few
slight turns it 'ends in a blunt point. It is retained in its position by a small
fold of peritoneum, which forms its mesentery. The csecal appendix is hol-
low as far as its extremity : and its cavity communicates with that of the
csecum by a small orifice, sometimes guarded by a valvulvar fold of mucous
membrane.
This appendix is peculiar, as far as is known, to man and certain of the
higher apes, and to the wombat ; but in some animals, as in the rabbit and
hare, the distal part of the csecum, being diminished in diameter and highly
glandular, may represent a condition of the appendix.
Ileo-ccecal or ileo-colic valve. — The lower part of the small intestine, as-
cending from left to right, and from before backwards, enters the commence-
ment of the large intestine, with a considerable degree of obliquity, about
two inches and a half from the bottom of the csecum, and opposite the junc-
tion of the latter with the ascending colon. The opening leading from the
ileum into the large intestine is guarded by a valve composed of two seg-
ments or folds. This is the ileo-cmcal or ileo-colic valve: it is also called the
valve of Bauhin and the valve of Tulpius, though Fallopius had described it
before either of those anatomists.
The entrance between the two segments of the valve is a narrow elongaied
aperture, lying nearly transverse to the direction of the great intestine.
The anterior end of this aperture, which is turned forwards and slightly to
the left, is rounded, but the posterior end is narrow and pointed. It is
bounded above and below by two prominent semilunar folds, which project
THE ILEO-COLIC VALVE.— THE COLON.
853
inwards towards the caecum and colon. The lower fold is the larger of
the two ; the upper is placed more horizontally. At each end of the
aperture these folds coalesce, and are then prolonged as a single ridge
Fig. 598. — VIEW OF THE ILEO-COLIO VALVE Fig. 598.
FROM THE LARGE INTESTINE. £
The figure shows the lowest part of the
ileum, i, joining the caecum, c, and the
ascending colon, o, which have been opened
anteriorly so as to display the ileo-colic
valve ; a, the lower, and c, the upper seg-
ment of the valve.
for a short distance round the cavity
of the intestine, forming the /rcena
or relinacula of the valve. The op-
posed surfaces of the marginal folds
•which look towards the ileum, and
are continuous with its mucous sur-
face, are covered like it with villi ;
while their other surfaces, turned to-
ward the large intestine, are smooth
and destitute of villi. When the
caecum is distended, the freena of the
valve are stretched, and the mar-
ginal folds brought into apposition,
so as completely to close the aperture and prevent any reflux into the ileum,
while at the same time no hindrance is offered to the passage of additional
matters from thence into the great intestine.
Each segment of the valve consists of two layers of mucous membrane,
continuous with each other along the free margin, and including between
them, besides the submucous areolar tissue, a number of muscular fibres, con-
tinued from the circular fibres of the ileum and from those of the large intes-
tine also. The longitudinal muscular fibres, and the peritoneal coat take no
part in the formation of the valve, but are stretched across it uninterruptedly
from one intestine to the other.
The ASCENDING COLON, situated in the right lumbar and hypochondriac
regions, commencing at the ccecum opposite to the ileo-csscal valve, ascends
vertically to the under surface of the liver, near the gall-bladder, where it
proceeds forwards and then turns abruptly to the left, forming what is
named the. hepatic flexure of the colon. The ascending colon is smaller than
the crecum, but larger than the transverse colon. It is overlaid in front by
some convolutions of the ileum, and is bound down firmly by the peritoneum,
which passes over its anterior surface and its sides, and generally leaves an
interval in which its posterior surface is connected by areolar tissue with the
fascia covering the quadratus lumborum muscle, and with the front of the
right kidney. In some cases, however, the peritoneum passes nearly round
it, and forms a distinct though very short right meso-colon.
The TRANSVERSE COLON passes across from the right hypochondrium,
through the upper part of the umbilical region, into the left hypochondrium.
Sometimes it is found as low as the umbilicus or even lower. At each
extremity it is situated deeply towards the back part of the abdominal
cavity, but in the middle it curves forwards, and lies close to the anterior
wall of the abdomen. Hence it describes an arch, the concavity of which is
854
THE INTESTINE.
turned towards the vertebral column ; and it has accordingly been named
the arch of the colon.
Above, the transverse colon is in contact with the under surface of the
liver, the gall-bladder, the great curvature of the stomach, and the lower
end of the spleen. Below it are the convolutions of the small intestine, the
third portion of the duodenum being behind it. It is invested behind by the
general peritoneum, and in front it adheres to the sac of the omen turn.
The DESCENDING COLON is continuous with the left extremity of the trans-
Terse colon by a sudden bend named the splenic flexure. It then descends
almost perpendicularly through the left hypochondriac and lumbar regions to
the left iliac fossa, where it ends in the sigmoid flexure. The peritoneum
affords a covering to it only in front and at the sides, whilst behind it is
connected by areolar tissue to the left crus of the diaphragm, the quadratus
lumborum, and the left kidney. It is usually concealed behind some convo-
lutions of the jejunum.
The SIGMOID FLEXURE of the colon, situated in the left iliac fossa, consists
of a double bending of the intestine upon itself in the form of the letter S,
immediately before it becomes continuous with the rectum at the margin of
the pelvis opposite to the left sacro-iliac articulation. It is attached by a
distinct meso-colon to the iliac fossa, and is very movable. It is placed im-
mediately behind the anterior parietes, or is concealed only by a few turns
of the small intestine. The sigmoid flexure is the narrowest part of the
colon.
Structure of tlie large intestine. — The walls of the large intestine consist
of four coats, like those of the stomach and small intestine, namely, the
serous, muscular, areolar, and mucous.
The serous and areolar coats require no further description here.
The muscular coat, like that of the other parts of the intestinal canal, con-
Fig. 599.
Im
Fig. 599. — OUTLINE SKETCH OF A SEC-
TION OP THE ASCENDING COLON, f
s, the serous or peritoneal covering ;
*', «', reflection of this at the attached
border forming a short wide mesentery,
between the folds of which the blood-
vessels are seen passing to the colon ; a,
one of the appendices epiploieae hanging
from the inner border ; Im, indicates at
the free border one of the three bands
formed by the thickening of the longi-
tudinal muscular coat; the dotted line
continued from the margins of these
bands represents the remainder of the
longitudinal muscular coat, and the
thick line within it, marked cm, repre-
sents the circular muscular layer ; m,
the mucous membrane at the flattened
part ; r, the crescentic bands or inden-
tations which divide the sacculi.
sists of external longitudinal and
internal circular fibres. The longi-
tudinal fibres, though found in a
certain amount all around the intestine, are, in the caecum and colon,
principally collected into three remarkable flat longitudinal bands. These
bands, sometimes called the ligaments of the colon, are about half an
MUSCULAR AND MUCOUS COATS OF THE COLON. 855
inch wide, and half a line tlr%k ; they commence upon the extremity of
the caecum, at the attachment of the vermiform appendix, and may
be traced along the whole length of the colon as far as the commence-
ment of the rectum, where they spread out, so as to surround that
part of the intestinal tube with a continuous layer of longitudinal muscular
fibres. One of these bands, named the posterior, is placed along the
attached border of the intestine ; another corresponds with its anterior
border, and, in the transverse colon, is situated at the attachment of the
great omentum ; whilst the third baud (lateral) is found along the free side
of the intestine, that is, on the inner border of the ascending and descend-
ing colon, and on the under border of the transverse colon. It is along the
course of this third band that the appendices epiploicse are most of them
attached. Measured from end to end, these three bauds are shorter than
the intervening parts of the tube ; and the latter are thus thrown into the
sacculi already mentioned : accordingly, when the bands are removed by
dissection, the sacculi are entirely effaced, and the colon, elongating consider-
ably, assumes the cylindrical form. The transverse constrictions seen on the
exterior of the intestine, between the sacculi, appear on the inside of the
intestine as sharp ridges separating the cells, and are composed of all its
coats. In the vermiform appendix the longitudinal muscular fibres constitute
an uniform layer.
The circular muscular fibres form only a thin layer over the general sur-
face of the caecum and colon, but are accumulated in larger numbers between
the sacculi. In the rectum, especially towards its lower part, the circular
fibres form a very thick and powerful muscular layer.
Fig. 600.
Fig. GOO.— SEMI-DIAGRAMMATIC VIEW OP A SMALL PORTION OF THE Mucous MEMBRANE
OF THE COLON. ™
A small portion of the mucous membrane cut perpendicularly at the edges is shown in
perspective ; on the surface are seen the orifices of the crypts of Liebeikuhn or tubular
glands, the most of them lined by their columnar epithelium, a few divested of it and
thus appearing larger ; along the sides the tubular glands are seen more or less equally
divided by the section ; these are resting on a wider portion of the submucous tissue,
from which the blood-vessels are in a part represented as passing into the spaces between
the glands.
The mucous membrane differs from the lining membrane of the small
intestine in having no folds, like the valvulse conniventes,' as also in being
quite smooth and destitute of villi. Viewed with a lens, its surface is seen
856 THE INTESTINE.
to bo marked all over by the orifices of numerous tubuli, resembling those
of the stomach and the crypts of the small intestine. These follicles are
arranged perpendicularly to the surface of the membrane ; they are longer
and more numerous, and are placed more closely together and at more
regular intervals than those of the small intestine. Their orifices are cir-
cular, and, when widened by the loss of their epithelial lining, they give the
mucous membrane a cribriform aspect.
Besides these, there are scattered over the surface of the whole large
intestine numerous closed follicles, similar to the solitary glands of the small
intestine, but marked by a depression passing down to them between the
surrounding tubules (Kolliker). They are most abundant in the cgecum and
in its vermiform appendix ; being placed closely all over the latter.
The epithelium, which covers the general surface of the mucous membrane,
and lines the tubuli and follicles, is of the columnar kind.
Vessels and Nerves. — In the great intestine of the rabbit, Frey figures the same
arrangement of capillary plexuses and venous radicles as has been described in the
stomach. He finds also in the rabbit clavate lacteals in rudimentary villi. (Zeitsch.
f. Wissensch. Zoologie, vol. xii.) ; but Teichmann's injections in the human subject
show no absorbents more superficial than the bases of the tubular follicles.
Nervous plexuses similar to those of the small intestine have also been found in the
walls of the large intestine.
THE RECTUM.
The lowest portion of the large intestine, named the rectum, extends from
the sigmoid flexure of the colon to the anus, and is situated entirely within
the true pelvis, in its back part.
Commencing opposite to the left sacro-iliac articulation, it is directed at
first obliquely downwards, and from left to right, to gain the middle line of
the sacrum. It then changes its direction, and curves forwards in front of
the lower part of the sacrum and the coccyx, and behind the bladder,
vesiciilae seminales and prostate in the male, and at the back of the cervix
uteri and vagina in the female. Opposite to the prostate it makes another
turn, and inclines downwards and backwards to reach the anus. The
intestinum rectum, therefore, so called from its original description being
derived from animals, is far from being straight in the human subject. Seen
from the front, the upper part of the rectum presents a lateral inclination
from the left to the median line of the pelvis, sometimes passing beyond
the middle to the right ; and when viewed from the side it offers two
curves, one corresponding with the hollow front of the sacrum and coccyx,
and the other at the lower end of the bowel, forming a shorter turn in the
opposite direction.
Unlike the rest of the large intestine, the rectum is not sacculated, but is
smooth and cylindrical ; and it has no separate longitudinal bands upon it.
It is about six or eight inches in length ; and is rather narrower than the
sigmoid flexure at its upper end, but becomes dilated into a large ampulla or
reservoir, immediately above the anus.
The upper part of the rectum is in contact in front with the back of tho
bladder (or uterus in the female), unless some convolutions of the small
intestine happen to descend into the interval between them. This part is
surrounded by peritoneum, which attaches it behind to the sacrum by a
duplicature named the meso-rectum. Lower down, the peritoneum covers
the intestine in front and at the sides, and at last its anterior surface only ;
SITUATION OF THE RECTUM.
857
still lower, it quits the intestine altogether, and is reflected forwards to
ascend upon the back of the bladder in the male, and of the upper part of
the vagina and the uterus in the female. In passing from the rectum to
the bladder, the peritoneum forms a cul-de-sac, or recto-vesical pouch,
which extends downwards between the intestine and the bladder to within
an inch or more from the base of the prostate, and is bounded on the sides
by two lunated folds of the serous membrane.
Fig. 601.
Fig. 601. — VERTICAL SECTION OP THE PELVIS AND ITS VISCERA IN THE MALE
(from Houston). |
This figure is introduced to illustrate the form, position, and relations of the rectum ;
it also shows the bladder and urethra with the pelvic inflection of the peritoneum over
these viscera : r, r, r, the upper and middle parts of the rectum, and at the middle
letter the fold separating the two; r a, the lower or anal portion ; v, the upper part of
the urinary bladder ; v', the base at the place where it rests more immediately on the
rectum ; p, the prostate gland and prostatic portion of the urethra ; b, the bulb ; c c,
the corpus cavernosum penis and suspensory ligament ; s c, the divided tissue within the
scrotum.
Below the point where the peritoneum ceases to cover it, the rectum is
connected to surrounding parts by areolar tissue, which is mostly loaded
with fat. In this way it is attached behind to the front of the sacrum and
the coccyx, and at the sides to the coccygei and levatores ani muscles. In
front, it is in immediate connection with a triangular portion of the base of
the bladder ; on each side of this, with the vesiculse seminales ; and farther
forwards, with the under surface of the prostate. Below the prostate,
wLere the rectum turns downwards to reach the anus, it becomes invested
by the fibres of the internal sphincter, and embraced by the levatores ani
858 THE INTESTINE.
muscles, by which it is supported. Lastly, at its termination it is surrounded
by the external sphincter aid muscle. In the female, the lower portion of
the rectum is firmly connected with the back of the vagina.
Structure. — The rectum differs in some respects from the rest of the large
intestine, in the structure of both its muscular and its mucous coats.
The muscular coat is very thick : the external or longitudinal fibres form
a uniform layer round it, and cease near the lower end of the intestine ; the
internal or circular fibres, on the contrary, become more numerous in that
situation, where they form what is named the internal sphincter muscle.
The longitudinal fibres are paler than the circular fibres, but both layers
become darker and redder towards the termination of the bowel.
The mucous membrane of the rectum is thicker, redder, and more vas-
cular than that of the colon ; and it moves freely upon the muscular coats ;
— in that respect resembling the lining membrane of the oesophagus. It
presents numerous folds of different sizes, and running in various directions,
nearly all of which are effaced by the distension of the bowel. Kear the
anus these folds are principally longitudinal, and seem to depend on the
contraction of the sphincter muscles outside the loosely connected mucous
membrane. The larger of these folds were named by Morgagni the columns
of the rectum (columnce rectC). Treitz states that these columns consist of
longitudinal muscular fibres, which terminate both superiorly and inferiorly
in elastic tissue. Higher up in the intestine, the chief folds are transverse
or oblique. Three prominent folds, larger than the rest, being half an inch
or more in depth, and having an oblique direction in the interior of the
rectum, have been pointed out specially by Houston. One of these pro-
jects backwards from the upper and fore part of the rectum, opposite the
prostate gland ; another is placed higher up, at the side of the bowel ; and
the third still higher. From the position and projection of these folds, they
may more or less impede the introduction of instruments. (Houston, Dublin
Hospital Reports, vol. v.)
Vessels and Nerves. — The arteries of the rectum spring from three sources, viz.
the superior hsemorrhoidal branches from the inferior mesenteric; the middle hse-
morrhoidal branches from the internal iliac directly or indirectly ; and, lastly, the
external or inferior haemorrhoidal branch from the pudic artery. The arrangement
of the vessels is not the same throughout the rectum. Over the greater part the
arteries penetrate the muscular coat at short interval?, and, at once dividing into
small branches, form a network by their communication. Towards the lower end, for
four or five inches, the arrangement differs. Here the vessels, having penetrated the
muscular coat at different heights, assume a longitudinal direction, passing in parallel
lines towards the end of the bowel. In their progress downwards they communicate
with one another at intervals, and they are very freely connected near the orifice,
where all the arteries join by transverse branches of considerable size. (Quain, Dis-
eases of the Rectum.)
The veins are very numerous, and form a complex interlacement resembling that
of the arteries just described, and named the hsemorrhoidal plexus. After following
a longitudinal course upwards similar to that of the arteries which they accompany,
they end partly in the internal iliac vein by branches which accompany the middle
hgemorrhoidal artery, and partly in the inferior mesenteric vein. Hence, the blood
from the rectum is returned in part into the vena cava, and in part into the portal
system. (See Fig. 325.)
The lymphatics enter some glands placed in the hollow of the sacrum, or those of
the lumbar series.
The nerves are very numerous, and are derived from both the cerebro-spinal
and the sympathetic systems. The former consist of branches derived from the
sacral plexus ; and the latter, of offsets from the inferior mesenteric and hypogastric
plexuses.
DEVELOPMENT OF THE ALIMENTARY CANAL. 859
THE ANUS AND ITS MUSCLES.
The anus, or lower opening of the alimentary canal, is a dilatable orifice,
surrounded internally by the mucous membrane, and externally by the skin,
which two structures here become continuous with and pass into each other.
The skin around the borders of the anus, which is thrown into wrinkles or
folds during the closed state of the orifice, is covered with numerous sensi-
tive papilla?, and is provided with hairs and sebaceous follicles.
The lower end of the rectum and the margin of the anus are, moreover,
embraced by certain muscles, which serve to support the bowel, and to close
its anal orifice. These muscles, proceeding from within outwards, are, the
internal sphincter, the levatores ani, the coccygei, and the external sphincter.
The three last muscles have already been described (pp. 262, 263).
The internal sphincter muscle (sphincter ani internus) is a muscular ring
or rather belt, surrounding the lower part of the rectum, an inch above the
anus, and extending over about half an inch of the intestine. It is two
lines thick, and is paler than the external sphincter. Its fibres are con-
tinuous above with the circular muscular fibres of the rectum, and, indeed,
it consists merely of those fibres more numerously developed than elsewhere,
and prolonged farther down than the external longitudinal fibres.
Kohlrausch describes a thin stratum of fibres between the mucous membrane and
the internal sphincter, these fibres having a longitudinal direction. Henle thinks
this is nothing more than the stratum of fibres belonging to the proper mucous
coat ; but Kohlrausch gives it a distinct name, the sustentator tunicae mucosse. (Kohl-
rausch, Anat. and Phys. d. Beckenorgane, Leipzig. 1854.)
DEVELOPMENT OF THE ALIMENTARY CANAL AND PERITONEAL CAVITY.
It has been already casually stated (p. 15) that the epithelial lining of the alimen-
tary canal is derived from the deepest of the three layers into which the germinal
membrane divides, while the rest of its walls are derived from a part of the middle
layer. To make this clear, it is necessary to state that, while those parts of the middle
layer of the embryo which lie next to the chorda dorsalis form the dorsal plates from
which the bones, nerves, and muscles of the trunk are derived, the lateral parts lying
beyond form, as described by Remak, the visceral plates, which on each side divide into
a deep and a superficial part, and, at the same time growing inwards, unite together on
the ventral aspect of the chorda dorsalis, forming by their union the mesial plate.
The superficial divisions of the two visceral plates, remaining in contact with the
outer epithelial layer of the embryo, form the cutis ; the deep division is the mus-
cul.o-intestinal layer, which forms the walls of the alimentary canal, with the exception
of its epithelial lining ; and the space between the superficial and deep divisions is
the common pleuro-peritoneal cavity, which becomes separated into the pleural and
peritoneal cavities in a subsequent stage of development.
The alimentary canal commences in the form of a groove which opens towards the
yelk-cavity of the ovum ; and the internal epithelial and musculo-intestinal layers in
which this groove is formed, nre continued round the yelk, constituting the walls of
the vitelline sac. The open groove is soon changed into a tube at each end, but is left
open in the middle upon the ventral aspect, and communicates at first by a wide
aperture, but later by means of a tube, named the omphalo-enteric canal or vitelline
duct, with the vitelline sac. This duct is soon obliterated, and the vitelline sac becomes
the umbilical vesicle, which is thereafter connected for a time with the embryo only
by a slender elongated pedicle, which enters at the umbilicus and is accompanied by
the omphalo-mesenteric vessels ; this pedicle is finally atrophied and disappears.
The alimentary canal, when it first assumes the tubular form, constitutes a simple
straight cylinder closed at each end, and placed along the front of the vertebral column,
to which it is closely attached at each extremity, whilst in the middle of its course it
is connected to the rest of the embryo by a median membranous fold, or rudimental
860
THE ALIMENTARY CANAL.
Fig. 602.
Fig. 602, A. — DIAGRAMMATIC SECTION SHOWING THE RELATION IN A MAMMAL AND IN
MAN BETWEEN THE PRIMITIVE ALIMENTARY CANAL AND THE MEMBRANES OF THE
OVUM.
The stage represented in this diagram corresponds to that of the fifteenth or seven-
teenth day in the human embryo, previous to the expansion of the allautois : c, the
villous chorion ; a, the amnion ; a', the place of convergence of the amnion and reflection
of the false amnion a" a", or outer or corneous layer ; e, the head and trunk of the
embryo, comprising the primitive vertebrse and cerebro-spinal axis ; i, i, the simple
alimentary canal in its upper and lower portions ; v, the yolk-sac or umbilical vesicle ;
v i, the vitello-intestinal opening ; w, the allantois connected by a pedicle with the anal
portion of the alimentary canal.
Fig. 602, B. — TRANSVERSE SECTION OP THE BODY OP AN EMBRYO, WITH A PART OP THE
ADJACENT MEMBRANES, SHOWING THE RELATION OP THE ALIMENTARY CAVITY TO THK
LAYERS OP THE GERMINAL MEMBRANE (from Remak and Kolliker). ^
1, chorda dorsalis ; 2, 3, spinal marrow ; 4, cuticular layer, and within it the pi-im-
ordial vertebral segments ; 5, the ventral or visceral plates, consisting of the cuticular
layer and the outer lamina of the middle germinal layer, passing at 4 x 5 from the
umbilicus into the amnion ; 5', within the embryo, is placed in the peritoneal cavity,
below one of the Wolflian bodies and close to the musculo-intestinal lamina ; 6, cavity of
the intestine lined by the epithelial or epithelio-glandular layer, which, along with the
musculo-intestinal, is continued by the ductus vitello-intestinalis into the yelk-sac, 5' 6.
mesentery. Soon, however, the intestine, growing in length, advances from the spine,
and forms a simple loop in the middle of the body, with a straight portion at its
upper and lower end, and at the same time becomes slightly dilated in the part destined
to form the stomach. The middle of the loop is connected with the umbilical vesicle
by the pedicle, and also by the omphalo-mesenteric vessels. The upper extremity of
the primitive alimentary tube reaches to the base of the skull and forms the oesophagus
and pharynx ; but the mouth is developed by depression of the outer surface of the
embryo, above the first branchial arch, and together with the tongue is at first sepa-
rated from the throat by a partition, which soon gives way. In like manner, the anal
orifice does not exist at first, but is formed by invagination of the outer surface, and
the opening of a communication between it and the intestine.
DEVELOPMENT OF THE ALIMENTARY CANAL.
Fig. 603.
861
Fig. 603. — OUTLINES OP THE FORM AND POSITION OP THE ALIMENTARY CANAL IN
SUCCESSIVE STAGES OP ITS DEVELOPMENT.
A, alimentary canal, &c., in an embryo of four weeks; B, at six weeks ; C, at eight
weeks ; D, at ten weeks ; I, the primitive lungs connected with the pharynx ; *, the
stomach ; d, duodenum ; i, the small intestine ; «', the large ; c, the caecum and vermi-
form appendage; r, the rectum; c I, in A, the cloaca ; a, in B, the anus distinct from
si, the sinus uro-geni tails ; v, the yolk sac; v i, the vitello-intestinal duct; u, the
urinary bladder and urachus leading to the allantois ; g, the genital ducts.
The dilated portion of the tube which forms the stomach turns over on its right
side, so that the border, which is connected to the vertebral column by the membra-
nous fold (or true mesogastrium) comes to be turned to the left, — the position of the
tube being still vertical, like the stomach of some animals. By degrees it becomes
more dilated, chiefly on what is now the left border but subsequently the great cur-
vature, and assumes first an oblique and finally a transverse position, carrying with
it the mesogastrium, from which the great omentum is afterwards produced. A
slight indication of the pylorus is seen at the third month. Upon the surface of the
part of the canal which immediately succeeds the stomach, and which forms the
duodenum, the rudiments of the liver, pancreas, and spleen are simultaneously depo-
sited : in connection with the two former, protrusions of the mucous membrane grow
into their blastemic mass and form the commencement of their principal ducts.
The place of distinction between the small and the large intestine, which is soon
indicated by the protrusion of the caecum, is at a point just below the apex or middle
of the simple loop already mentioned. As the small intestine grows, the part
below the duodenum forms a coil which at first lies in the commencing umbilical
cord, but retires again into the abdomen about the tenth week ; afterwards it con-
tinues to elongate, and its convolutions become more and more numerous.
The large intestine is at first less in calibre than the small. In the early embryo
there is at first no caecum. This part of the bowel gradually grows out from the rest,
and in the first instance forms a tube of uniform calibre, without any appearance of
the vermiform appendix : subsequently the lower part of the tube ceases to grow in
the same proportion, and becomes the appendix, whilst the upper portion continues
to be developed with the rest of the intestine. The caecum now appears as a protru-
sion a little below the apex of the bend in the primitive intestinal tube, and, together
with the commencing colon, and the coil of small intestine, is at first lodged in the
wide part of the umbilical cord which is next the body of the embryo. The ileo-
caecal valve appears at the commencement of the third month. When the coils of
intestine and caecum have retired from the umbilicus into the abdomen, the colon
862
THE ALIMENTARY CANAL.
is at first entirely to the left of the convolutions of the small intestines, but subse-
quently the first part of the large intestine, together with the meso-colon, crosses
over the upper part of the small intestine, at the junction of the duodenum and
jejunum. The caecum and transverse colon are then found just below the liver;
finally, the caecum descends to the right iliac fossa, and at the fourth or fifth month
the parts are in the same position as in the adult. At first, villous processes or
folds of various lengths are formed throughout the whole canal. After a time these
disappear in the stomach and large intestine, but remain persistent in the inter-
mediate portions of the tube. According to Meckel, the villous processes are formed
from larger folds, which become serrated at the edge and divided into separate villi.
The mode of development of the alimentary canal accounts, in some measure, for
the principal complication in the folds of the peritoneum. The stomach being origi-
nally straight in form and mesial in position, the small omentum and gastro-phrenic
ligament must be regarded as an originally mesial fold with the free edge directed
forwards, which afterwards forms the anterior boundary of the foramen of Winslow.
Thus the anterior wall of the sac of the omentum, as far as the great curvature of the
stomach, may be considered as formed by the right side of a mesial fold, while the
peritoneum in front of the stomach belongs to the left side of the same, and a sac of
the omentum is a natural consequence of the version and disproportionate growth of
the tube between the duodenum and the cardiac orifice of the stomach. It is obvious
that the view of the omental sac, according to which its posterior layers are held
to return to the duodenum and posterior wall of the body before proceeding to form
the transverse meso-colon (p. 829) is more consistent with the phenomena of deve-
lopment now described, than that which would make them directly enclose the colon.
On the other hand, the further elongation of the omental sac and the whole disposition
of the peritoneum, with respect to the colon, must be regarded as having taken place
after the assumption by the great intestine of its permanent position.
Fig. 603*.
Fig. 603*.— SKETCH OF THE HUMAN
EMBRYO OP THE EIGHTH OR NINTH
WEEK, SHOWING THE COIL OF INTESTINE
IN THE UMBILICAL CORD.
The amnion and villous chorion have
been opened and the embryo drawn aside
from them ; v, the umbilical vesicle or
yolk-sac placed between the amnion and
chorion, and connected with the coil of
intestine, i't by a small or almost linear
tube ; the figure at the side repre-
sents .the first part'of the umbilical cord
magnified ; i, coil of intestine ; vi, vitello-
intestinal duct, alongside of which are
seen omphalo-mesenteric blood-vessels.
The occurrence of umbilical hernia in
its various degrees may be referred to the persistence of one or other of the foetal
conditions in which a greater or less portion of the intestinal, canal is contained in
the umbilical cord ; and it has been shown that the most common diverticulum of
the small intestine is connected with the original opening of the ductus vitello-intes-
tinalis into the ileum (p. 841).
THE LIVER
The liver is an important glandular organ, very constant in the animal
series, being found in all vertebrate, and, in a more or Itss developed con-
dition, in most invertebrate tribes. It elaborates and secretes the bile, and
otherwise acts, in a manner as yet imperfectly understood, as an elaborator
and purifier of the blood. In the exercise of this latter function, there is
formed in its texture an amyloid substance, very easily converted into sugar.
The liver is the largest gland in the body, and by far the most bulky of
FORM OF THE LIVER.
863
the abdominal viscera. It measures about ten or twelve inches transversely
from right to left, between six aiid seven inches from its posterior to its
anterior border, and about three and a half inches from above downwards at
its thickest part, which is towards the right and posterior portion of the
Fig. 604. — SKETCH OP THE UNDER
SURFACE OF THE LlVER. \
The anterior border is turned
upwards, and ths blood-vessels
and ducts have been removed : 1,
the right lobe ; 2, the left lube ;
3, 4, the longitudinal fissure ; 3,
its umbilical part ; 4, part con-
taining the ductus venosus ; 5,
transverse or portal fissure ; 6,
lobulus quadiatus ; 7, lobulus
Spigelii ; 8, lobulus caudatus ;
9, fissure or fossa of the vena
cava ; 10, the gall-bladder in its
Fig. 604.
gland. The average bulk,
according to Krause, is
eighty-eight cubic inches ;
according to Beale, one
hundred. The ordinary weight in the adult is stated to be between three
and four pounds, or more precisely from fifty to sixty ounces avoirdupois.
According to the facts recorded by Reid, the liver weighed, in 43 cases out of 82,
between 48 and 58 ounces in the adult male ; and in 17 cases out of 36, its weight in
the adult female ranged between 40 and 50 ounces. It is generally estimated to be
equal to about- l-36th of the weight of the whole body ; but in the foetus, and in early
life, its proportionate weight is greater. (Reid, in Lond. and Edin. Monthly
Journal of Med. Science, April, 1843.)
The specific gravity of the liver, according to Krause and others, is between 1*05
and 1-06 : in fatty degeneration this is reduced to 1*03, or even less.
The parenchyma of the liver has an acid reaction (Kolliker). Beale gives the
following results of his analysis of the liver of a healthy man, who was killed by a
fall.
Water ....
Solid matters .
Fatty matters
Albumen
Extractive matters
Alkaline salts
Vessels, &c. insoluble in water
Earthy salts
68-58
31-42
3-82
4-67
5-40
1-17
16-03
•33
100-00
The liver is a solid organ, of a dull reddish-brown colour, with fre-
quently a dark-purplish tinge along the margin. It has an upper smooth
and convex surface, and an under surface which is uneven and concave ;
the circumference is thick and rounded posteriorly and towards the right
extremity, but becomes gradually thinner towards the left and in front,
where it forms the sharp anterior and left lateral margins.
The upper surface is convex, smooth, and covered with peritoneum. It
is marked off into a right portion, large and convex, and a left portion,
86 i THE LIVER.
smaller and flatter, by the line of attachment of the fold of peritoneum
named the falciform ligament.
The under surface, looking downwards and backwards, is concave and
uneven, invested with peritoneum everywhere except where the gall-blad-
der is adherent to it, and at the portal fissure and fissure of the ductus
venosus, which give attachment to the small omentum, the fold of peri-
toneum which passes round the blood-vessels and ducts of the viscus. On
this surface the lobes and fissures of the liver are observed.
The lobes of the liver, five in number, are named the right and the left,
the lobe of Spigelius, the caudate or tailed lobe, and the square lobe.
The right and left lobes are separated from each other on the under sur-
face by the longitudinal fissure, and in front by the interlobular notch :
on the convex surface of the liver there is no other indication of a sepa-
ration between them than the line of attachment of the broad ligament.
The right lobe is much larger and thicker than the left, which constitutes
only about one-fifth or one-sixth of the entire gland.
The other three lobes are small, and might be said to form parts of the
right lobe, on the under surface of which they are situated.
The lobulus quadratus is that part which is situated between the gall-
bladder and the great longitudinal fissure, and in front of the fissure for the
portal vein. Its greatest diameter is from before backwards.
The lobulus Spigelii, more prominent and less regular in shape than the
quadrate lobe, lies behind the fissure for the portal vein, and is bounded
on the right and left by the fissures which contain the inferior vena cava
and the remains of the ductus venosus.
The lobulus caudatus is a sort of ridge which extends from the base of
the Spigelian lobe to the under surface of the right lobe. This, in the
natural position of the parts, passes forwards above the foramen of Wins-
low, the Spigelian lobe itself being situated behind the small omentum, and
projecting into the omental sac.
The fissures. — These are likewise five in number, and are seen on the
under surface only. They have all been already incidentally referred to.
The transverse fissure, or portal fissure, is the most important, be-
cause it is here that the great vessels and nerves enter, and the hepatic
duct passes out. It lies transversely between the lobulus quadratus and
lobulus Spigelii, and meets the longitudinal fissure nearly at right angles.
At the two extremities of this fissure, the right and left divisions of the
hepatic artery and portal vein, together with the nerves and deep lympha-
tics enter the organ, while the right and left hepatic ducts emerge.
The longitudinal fissure, which separates the right and the left lobes
of the liver from each other, is divided into two parts by its meeting
with the transverse fissure. The anterior part, named the umbilical fissure,
contains the umbilical vein in the foetus, and the remnant of that vein
in the adult, which then constitutes the round ligament. It is situated
between the square lobe and the left lobe of the liver, the substance of
which often forms a bridge across the fissure, so as to convert it partially
or completely into a canal. The posterior part is named the fissure of the
ductus venosus (fossa ductus venosi) ; it continues the umbilical fissure back-
wards between the lobe of Spigelius and the left lobe ; and it lodges the
ductus venosus in the foetus, and in the adult a slender cord or ligament
into which that vein is converted.
The fissure or fossa of the vena cava is situated at the back part of the
liver, between the Spigelian lobe on the left and the right lobe, and is
RELATIONS OF THE LIVER. 865
separated from the transverse fissure by the caudate lobe. It is prolonged
upwards in an oblique direction to the posterior border of the liver, and
may be said to join behind the Spigelian lobe with the fissure for the
ductus venosus. It is at the bottom of this fossa that the blood leaves the
liver by the hepatic veins, which end here in the vena cava. The sub-
stance of the liver in some cases unites around the vena cava, and encloses
that vessel in a canal.
The last remaining fissure, or rather fossa (fossa cystis fellese), is that
for the lodgment of the gall-bladdar ; it is sometimes continued into a
slight notch on the anterior margin of the liver.
Two shallow impressions are seen on the under surface of the right lobe ;
one in front (impressio colica), corresponding with the hepatic flexure of
the colon ; and one behind (impressio renalis), corresponding with the right
kidney.
The anterior border of the liver, a thin, free, and sharp margin, is the
most movable part of the gland. Opposite the longitudinal fissure the
anterior border presents a notch, and, to the right of this, there is often
another slight notch opposite the fund as of the gall-bladder.
The posterior border of the liver, which is directed backwards and up-
wards, is thick and rounded on the right side, but becomes gradually
thinner towards the left. It is the most fixed part of the organ, and is
firmly attached by areolar tissue to the diaphragm. This border of the
liver is curved opposite to the projection of the vertebral column, and has
a deep groove for the reception of the ascending vena cava.
Of the two lateral borders of the liver, the right is placed lower down,
and is thick and obtuse ; whilst the left is the thinnest part of the gland,
is raised to a higher level, and reaches the cardiac part of the stomach.
Ligaments. — The ligaments of the liver, like its lobes and fissures, are
commonly described as five, but it seems scarcely necessary to give distinct
names to so many parts which are only folds of membrane. One of these,
the coronary ligament, is the fold of peritoneum by which the posterior border
of the liver is attached to the diaphragm : this border lies in contact with
the diaphragm, in the greater part of its extent, between the upper and
under layers of the peritoneal fold ; but toward the two extremities of the
organ these layers come into contact, and form two short mesenteries — the
right and left triangular ligaments, of which the left is the longer and more
distinct. Another of these so-called ligaments is the broad, falciform, or
suspensory ligament, a wide thin membrane, composed of two layers of
peritoneum, closely united together. By one of its margins it is connected
with the under surface of the diaphragm, and with the posterior surface of
the sheath of the right rectus muscle of the abdomen as low as the
umbilicus ; by another it is attached along the convex surface of the liver,
from its posterior border to the notch in its anterior border : the remaining
margin is free, and contains between its layers the round ligament, a dense
fibrous cord, the remnant of the umbilical vein of the foetus, which ascends
from the umbilicus, within the lower edge of the broad ligament, and
enters the longitudinal fissure on the under surface. These structures
have been already referred to (p. 827).
Position with regard to neighbouring parts. — Occupying the right hypo-
chondriac region, and extending across the epigastric region into a part of
the left hypochondrium, the liver is accurately adapted to the vault of the
diaphragm above, and is covered, to a small extent in front, by the abdominal
parietes. The right portion reaches higher beneath the ribs than the left,
3 L
866 THE LIVER.
corresponding thus with the elevated position of the diaphragm on the right
side. By means of the diaphragm, the liver is separated from the concave
base of the right lung, the thin margin of which descends so as to intervene
between the surface of the body and the solid mass of the liver — a fact well
known to the auscultator.
The convex surface of the liver is protected, on the right, by the six or
seven lower ribs, and in front by the cartilages of the same and by the
ensiform cartilage — the diaphragm, of course, being interposed. Being
suspended by ligaments to the diaphragm above, and supported below, in
common with the rest of the viscera, by the abdominal muscles, the situa-
tion of the liver is modified by the position of the body, and also by the
movements of respiration ; thus, in the upright or sitting posture, the liver
reaches below the margin of the thorax ; but in the recumbent position, the
gland ascends an inch or an inch and a half higher up, and is entirely
covered by the ribs, except a small portion opposite the substernal notch.
Again, during a deep inspiration, the liver descends below the ribs, and in
expiration retires upwards behind them. In females the liver is often per-
manently forced downwards below the costal cartilages, owing to the use
of tight stays ; sometimes it reaches nearly as low as the crest of the
ilium ; and, in many such cases, its convex surface is indented from the
pressure of the ribs.
To the left of the longitudinal fissure the liver is supported on the pyloric
Fig. 605.
Fig. 605. — LOWER SURFACE OF THE LIVER WITH THE PRINCIPAL BLOOD-VESSELS AND
DUCTS (from Sappey). £
The liver has been turned over from left to right so as to expose the lower surface.
1, left lobe; 2, 3, 4, 5, right lobe; 6, lobulus quadratus ; 7, pons hepatis; 8, 9, 10,
lobulus Spigelii; 11, lobulus caudatus ; 12, 13, transverse or portal fissure with the
great vessels ; 14, hepatic artery ; 15, vena portee ; 16, anterior part of the longitudinal
fissure, containing 17, the round ligament or obliterated remains of the umbilical vein ;
18, posterior part of the same fissure, containing 19, the obliterated ductus venosus; 20,
21, 22, gall-bladder ; 23, cystic duct ; 24, hepatic duct ; 25, fossa containing 26, the
vena cava inferior; 27, opening of the capsular vein ; 28, small part of the trunk of the
right hepatic vein ; 29, trunk of the left hepatic vein ; 30, 31, openings of the right and
left diaphragmatic veins.
VESSELS, NERVES, AND DUCTS OF THE LIVER. 867
extremity and anterior surface of the stomach, on which it moves freely.
When the stomach is quite empty, the left part of this surface of the liver
may overlap the cardiac end of that viscus. To the right of the longitu-
dinal fissure the liver rests and moves freely upon the first part of the duo-
denum, and upon the hepatic flexure of the colon, at the junction of the
ascending and transverse portions of that intestine. Farther "back it is in
contact with the fore part of the right kidney and suprarenal capsule.
Vessels. — The two vessels by which the liver is supplied with blood are
the hepatic artery and the vena portse. The hepatic artery (p. 408), a
branch of the cceliac axis, is intermediate in size between the other two
branches of that trunk, being larger than the coronary artery of the
stomach, but not so large as the splenic artery. Its size is, therefore, small
in comparison with the organ to which it is distributed. It enters the
transverse fissure, and there divides into a right and a left branch, for the
two principal lobes of the liver.
By far the greater part of the blood which passes through the liver, — and
in this respect it differs from all other organs of the body, — is conveyed to it
by a large vein, the vena portce (p. 479). This vein is formed by the union
of nearly all the veins of the chylopoietic viscera, viz., those from the
stomach and intestines, the pancreas and spleen, the ornentum and mesen-
tery, and also those from the gall-bladder. It enters the porta, or trans-
verse .fissure, where, like the hepatic artery, it divides into two principal
branches.
The hepatic artery and portal vein, lying in company with the bile-duct,
ascend to the liver between the layers of the gastro-hepatic omentum, above
the foramen of Winslow, and thus reach the transverse fissure together.
The relative position of the three structures is as follows, — The bile-duct ia
to the right, the hepatic artery to the left, and the large portal vein is behind
the other two. They are accompanied by numerous lymphatic vessels and
nerves. The branches of these three vessels accompany one another in their
course through the liver nearly to their termination ; and in this course are
surrounded for some distance by a common investment (Glisson's capsule),
which is prolonged into the interior of the organ.
The hepatic veins, which convey the blood away from the liver, pursue
through its substance an entirely different course from the other vessels, and
pass out at its posterior border, where, at the bottom of the fossa already
described, they end by two or three principal branches, besides other smaller
ones, in the vena cava inferior.
The lymphatics of the liver, large and numerous, form a deep and a
superficial set, already described (p. 493).
Nerves. — The nerves of the liver are derived partly from the coeliac plexus,
and partly from the pneumogastric nerves, especially from the left pneumo-
gastric. They enter the liver supported by the hepatic artery and its
branches ; along with which they may be traced a considerable way in the
portal canals, but their ultimate distribution is not known.
EXCRETORY APPARATUS. — The excretory apparatus of the liver consists of
the hepatic duct, the cystic duct, the gall-bladder, and the common bile-
duct.
The hepatic duct, formed by the union of a right and left branch, which
issue from the bottom of the transverse fissure and unite at a very obtuse
angle, descends to the right, within the gastro-hepatic omentum, in front of
the vena portae, and having the hepatic artery to its left side. Its diameter
is about two lines, and its length nearly two inches. At its lower end it
3 L 2
868 THE LIYEE.
meets with the cystic duct, descending from the gall-bladder ; and the two
ducts uniting together at an acute angle, form the common bile-duct.
The gall-bladder is a receptacle or reservoir for such bile as is not imme-
diately required in digestion. It is a pear-shaped membranous sac, three
or four inches long, about an inch and a half across at its widest part,
and capable of containing from eight to twelve fluid-drachms. It is lodged
obliquely in a fossa on the under surface of the right lobe of the liver, with
its large end or fundus, which projects beyond the anterior border of tho
gland, directed downwards, forwards, and to the right, whilst its neck is
inclined in the opposite direction.
The upper surface of the gall-bladder is attached to the liver by areolar
tissue and vessels, along the fossa formed between the qimdrate lobe and
the remainder of the right lobe. Its under surface is free and covered by
the peritoneum, which is here reflected from the liver, so as to include
and support the gall-bladder. Sometimes, however, the peritoneum com-
pletely surrounds the gall-bladder, which is then suspended by a kind of
mesentery at a little distance from the under surface of the liver. The
fundus of the gall-bladder, which is free, projecting, and always covered
with peritoneum, touches the abdominal parietes immediately beneath the
margin of the thorax, opposite the tip of the tenth costal cartilage. Below,
it rests on the commencement of the transverse colon ; and, farther back,
it is in contact with the duodenum, and sometimes with the pyloriq ex-
tremity of the stomach. The neck of the gall-bladder, gradually narrowing,
forms two curves upon itself like the letter S, and then, becoming much con-
stricted, and changing its general direction altogether, it bends downwards
and terminates in the cystic duct.
The gall bladder is supplied with blood by the cystic branch of the right
division of the hepatic artery, along which vessel it also receives nerves from
the cceliac plexus. The cystic veins empty themselves into the vena portae.
Beale states that two large veins always accompany one artery.
The cystic duct is about an inch and a half in length. It runs downwards
and to the left, thus forming an angle with the direction of the gall-bladder,
and unites with the hepatic duct to form the common duct.
The common bile-duct, ductus communis choledochus, the largest of the
ducts, being from two to three lines in width, and nearly three inches in
length, conveys the bile both from the liver and the gall-bladder into the
duodenum. It continues downwards and backwards in the course of the
hepatic duct, between the layers of the gastro-hepatic omentum, in front of
the vena portse, and to the right of the hepatic artery. Having reached
the descending portion of the duodenum, it continues downwards on the
inner and posterior aspect of that part of the intestine, covered by or in-
cluded in the head of the pancreas, and, for a short distance, in contact with
the right side of the pancreatic duct. Together with that duct, it then
perforates the muscular wall of the intestine, and, after running obliquely
for three quarters of an inch between its several coats, and forming an
elevation beneath the mucous membrane, it becomes somewhat constricted,
and opens by a common orifice with the pancreatic duct on the inner surface
of the duodenum, at the junction of the second and third portions of that
intestine, and three or four inches below the pylorus.
Varieties. — The liver is not subject to great or frequent deviation from its ordinary
form and relations. Sometimes it retains the thick rounded form which it presents
in the foetus ; and it has occasionally been found without any division into lobes.
On the contrary, Soemmerring has recorded a case in which the adult liver was
LOBULES OF THE HEPATIC SUBSTANCE. 869
divided into twelve lobes ; and similar cases of subdivided liver (resembling that of
some animals) have been now and then observed by others. A detached portion,
forming a sort of accessory liver, is occasionally found appended to the left extremity
of the gland by a fold of peritoneum containing blood-vessels.
The gall bladder is occasionally wanting ; in which case the hepatic duct is much
dilated within the liver, or in some part of its course. Sometimes the gall-bladder is
irregular in form, or is constricted across its middle, or, but much more rarely, it is
partially divided in a longitudinal direction. Direct communications by means of
small ducts (named hepato-cystic), passing from the liver to the gall-bladder, exist
regularly in various animals; and they are sometimes found, as an unusual formation,
in the human subject.
The right and left divisions of the hepatic duct sometimes continue separate for
some distance within the gastro-hepatic omentum. Lastly, the common bile-duct
not unfrequently opens into the duodenum, apart from the pancreatic duct.
STRUCTURE OF THE LIVER.
Coats. — The liver has two coverings, viz., a serous or peritoneal invest-
ment, already sufficiently referred to, and a proper areolar coat.
The areolar or fibrous coat invests the whole gland. Opposite to the
parts covered by the serous coat, it is thin and difficult to demonstrate ;
but where the peritoneal coat is absent, as at the posterior border of the
liver, and in the portal fissure, it is denser and more evident. Its inner
surface is attached to the hepatic glandular substance, being there continuous
Fig. 606.
Fig. 606. — SECTION OP A PORTION OP LIVER PASSING LONGITUDINALLY THROUGH A
CONSIDERABLE HEPATIC VEIN, FROM THE PIG (after Kiernan). f
H, hepatic venous trunk, against which the sides of the lobules (1) are applied ; h, h, h,
sublobular hepatic veins, on which the bases of the lobules rest, and through the coats of
which they are seen as polygonal figures ; i, mouth of the intralobular veins, opening into
the sublobular veins ; i', intralobular veins shown passing up the centre of some divided
lobules ; I, I, cut surface of the liver ; c, c, walls of the hepatic venous canal, formed by
the polygonal bases of the lobules.
870
THE LIVER.
with the delicate areolar tissue which lies between the small lobules of the
gland. At the transverse fissure it becomes continuous with the capsule of
Glisson, by which name is designated a sheath of areolar tissue which sur-
rounds the branches of the portal vein, hepatic artery, and hepatic duct, as
they ramify in the substance of the liver, and which becomes more delicate
as the vascular branches become smaller.
Lobules. — The proper substance of the liver, which has a reddish brown
colour and a mottled aspect, is compact, but not very firm. It is easily
cut or lacerated, and is not unfrequently ruptured during life from accidents
in which other parts of the body have escaped injury. When the substance
of the liver is torn, the broken surface is not smooth but coarsely granular,
the livtr being composed of a multitude of small lobules, which vary from
half a line to a line in diameter.
These lobules are closely packed polyhedral masses, and in some animal s,
as in the pig, are completely isolated one from another by areolar tissue con-
tinuous with the fibrous coat of the liver and with the capsule of Glisson ;
but in the human subject, and in most animals, although they are very dis-
tinguishable on account of the disposition both of vessels and parenchyma,
they are not distinctly separated, but exhibit continuity through their
capillary networks and cellular constituents. Notwithstanding this, how-
ever, we may consider the lobules of the human liver as being marked out
by slight iuterlobular intervals.
Fig. 607.
Fig. 607. — LONGITUDINAL SECTION
OF A PORTAL CANAL, CONTAINING
A PORTAL VEIN, HEPATIC
ARTERY, AND HEPATIC DUCT,
FROM THE PIG (after Kiernan). f
p, branch of vena portse, situated
in c, c, a portal canal, formed
amongst the lobules of the liver
(£, 0 ') Pi Pt vaginal branches of
portal vein, giving off smaller ones
(i, i), named interlobular veins;
there are also seen within the large
portal vein numerous orifices of the
smallest interlobular veins arising
directly from it ; a, hepatic artery ;
d, hepatic duct.
The lobules of the liver
have throughout its substance
in general the polyhedral form
of irregularly compressed sphe-
roids ; but on the surface they
are flattened and angular.
They are all compactly ar-
ranged round the sides of
branches of the hepatic veins, each lobule resting by a smooth surface or
base, upon the vein, and being connected with it by a small venous trunk,
which arises in the centre of the lobule, and passes out from the middle of
its base to end in the larger subjacent vessel. The small veins proceeding
from the centre of the lobules are named the intralobular veins, and those
on which the lobules rest, the sublobular veins. If one of these sublobular
veins be opened, the bases of the lobules may be seen through the coats of
BLOOD-VESSELS OF THE LOBULES. 871
the vein, which are here very thin, giving a tesselated appearance, each little
polygonal space representing the base of a lobule, and having in its centre a
small spot, which is the mouth of the intralobular vein. When divide! in
the direction of a sublobular vein, the attached lobules present a foliated
appearance, for that part of their surface which is not in contact with the
vein is itself slightly lobulated. Cut in a transverse direction, the lobules
present a polyhedral form.
The hepatic substance, as exhibited in the arrangement of each lobule,
consists of masses of cells and a copious vascular network, closely inter-
woven, with the intervention of little other tissue. For the sake of con-
venience, the vascular structure of the liver may be considered first.
Blood-vessels. — The hepatic veins commence in the centre of each lobule
by the union of its capillary vessels into a single independent intralobular
Fig. COS.— CAPILLARY NETWORK OP THE LOBULES OP THE RABBIT'S LIVER (from
Kolliker). ^
The figure is taken from a very successful injection of the hepatic veins made by
Harting : it shows nearly the whole of two lobules, and parts of three others : p, portal
branches running in the interlobular spaces ; h, hepatic veins penetrating and radiating
from the centre of the lobules.
vein, as already stated. These minute intralobular veins open at once into
the sides of the adjacent sublobular veins. The sublobular veins are of
various sizes, and anastomose together. Uniting into larger and larger
vessels, they end at length in hepatic venous trunks, which receive no
intralobular veins. Lastly, these venous trunks, converging towards the
posterior border of the liver, and receiving in their course other small sub-
lobular veins, terminate in the vena cava inferior, as already described. In
this course the hepatic veins and their successive ramifications are unac-
companied by any other vessel. Their coats are extremely thin j the sub-
lobular branches adhere immediately to the lobules, and even the larger
trunks have but a very slight areolar investment connecting them to the
substance of the liver. Hence the divided ends of these veins are seen upon
a section of the liver as simple open orifices, the thin wall of the vein being
surrounded closely by the solid substance of the gland.
The vena portse and hepatic artery, which, together with the biliary ducts,
872
THE LIYEE.
enter the liver at the transverse fissure, have a totally different course,
arrangement and distribution from those of the hepatic vein. Within the
liver the branches of these three vessels lie together in certain canals, called
Fig. 609.
Fig. 609. — INJECTED TWIG OF A HEPATIC VEIN WITH SUBLOBULAR VEINS PASSING INTO
THE HEPATIC LOBULES (from Sappey). ™
1, small sublobular hepatic vein ; 2, intralobular veins passing into the base of the
lobules ; 3, their smaller subdivisions; 4, capillary network of communication with the
extreme ramifications of the vena porlso.
Fig. 610.
Fig. 610. — CROSS SECTION OP A LOBULE OP THE HUMAN LIVER, IN WHICH THE CAPILLARY
NETWORK BETWEEN THE PORTAL AND HEPATIO VEINS HAS BEEN FULLS? INJECTED (from
Sappey). ^
1, section of the intralobular vein ; 2, its smaller branches collecting blood from the
capillary network ; 3, interlobular branches of the vena portse with their smaller ramifi-
cations passing inwards towards the capillary network in the substance of the lobule.
MIXUTE STRUCTURE OF THE LOBULES. 873
portal canals, which are tubular passages formed in the substance of the
gland, commencing at the transverse fissure, and branching upwards and
outwards from that part in all directions. Each portal canal (even the
smallest) contains, as shown in a longitudinal section, one principal branch
of the vena portae, of the hepatic artery, and of the biliary duct ; the whole
being invested within the larger portal canals by the areolar tissue of the
capsule of Glissou.
The portal vein subdivides into branches which ramify between the lobules,
anastomosing freely around them, and are named interlobular veins. The
twigs from these penetrate the lobules at their circumference, and end in the
capillary network from which the iutralobular (hepatic) veins take origin.
Within the portal canals the branches of the portal veins receive small
tributaries called "vaginal veins," which return to them the blood which has
circulated in the capsule of Glisson, and also "vense advehentes capsulares,"
from the fibrous coat of the liver.
The hepatic artery terminates in three sets of branches, termed vaginal,
capsular, and interlobular. The vaginal branches ramify within the portal
canals, supplying the walls of the ducts and Glisson's capsule. The capsular
branches appear on the surface of the liver spread out on the fibrous sheath,
and are accompanied by the veins which return their blood to the portal
branches. The interlobular branches accompany the interlobular veins,
but are of much smaller diameter. It has been supposed by Kiernan,
Ferreiu, and Theile, that the blood which they convey is entirely taken up
by the portal veins before reaching the capillaries from, which the hepatic
veins take origin ; but the view, which has been held by other anatomists,
that the hepatic arteries, transmit blood directly to the capillary network
between the portal and hepatic veins, is supported by the experiments of
Chrzonszczewsky, mentioned further on.
The capillary network is very close, and, in specimens in which it has been
filled with transparent injection, can be seen to be continued uninterruptedly
from one lobule to another.
The distribution of the portal and hepatic veins within the lobules, as just described,
has suggested an explanation of the mottled aspect of the liver, an appearance which
formerly led to the erroneous idea of there being two substances in each lobule, one
darker than the other. The colour of the hepatic substance itself is pale yellow, and
would be uniform throughout, were it not varied according to the quantity of blood
contained in its different vessels. Thus, if the system of hepatic veins be congested, the
centre of each lobule is dark, and its margin pale : this is the common case after death,
and is named by Kiernan passive congestion. In what is considered an active state
of hepatic congestion, the dark colour extends to the portal system, across the inter-
lobular fissures, leaving intermediate spaces, which remain as irregular pale spots :
this state occurs especially in diseases of the heart. When, on the other hand, the
portal system is congested, which is rare, and occurs generally in children, the mar-
gins of the lobules are dark, and their centres pale.
The Hepatic Cells. — The principal part of the secreting substance of the
liver, and that which seems to form nearly the whole bulk of the lobules
when unprepared sections are examined with the microscope, consists of
nucleated cells. The hepatic cells are of a spheroidal, compressed, or poly-
hedral form, having a mean diameter of from T^-g-r)th to -^i^th of an inch :
according to Henle some of them are only -p^^th of an inch in dia-
meter. They present some colour even when highly magnified, being of
a faint yellowish hue. They usually include a very clear bright vesicular
nucleus of a rounded form, within which again one or two nucleoli may be
874
THE LITER.
Fig. 612.
seen. The cells also contain very fine granular or vesicular molecules. In
many cases, too, the cells of the human liver and of that of quadrupeds have
larger and smaller semi-
Fig. 611. transparent fat-globules in
their interior. The nu-
cleus is frequently quite in-
distinguishable ; aud not
unfrequently, on the other
hand, cells are observed
which are provided with
two separate nuclei. They
are massed in rows or
streaks between the vessels,
and, in sections made at
right angles to the iutra-
lobular veins, appear as if
Fig 611. — A SMALL PORTION
OF A LOBULE OF TEE HUMAN
LlVER HIGHLY MAGNIFIED,
SHOWING THE HEPATIC CELLS
IN CONNECTION AND THE CA-
PILLARY SPACES BETWEEN
THEM (from Kolliker). A*>
Fig. 612. — SEPARATE HEPATIC
CELLS (from Kolliker). i§s»
a, most usual form of cells ;
&, cells containing colour-gra-
nules ; c, cells containing fat-
globules.
radiating from the centre
of the lobules towards their
circumference. When ex-
amined with a higher mag-
nifying power, they are
observed to form a con-
tinuous web, or solid net-
work, the more obvious
openings in which are the spaces occupied by the capillaries with which the
cells are interlaced.
Beale states that these cells often appear to be collections of viscid matter around
central nuclei, without any distinct cell-wall ; but this is open to question. According
to Schiff (quoted by Henle), the molecules contained within the hepatic cells consist
of the amyloid substance, which is formed in the liver, and from which the glucose
obtained from this organ is derived.
The hepatic cells may be washed away from thin sections by dilute solu-
tions of caustic potash, and then the spaces which they occupied are emptied,
and the network of capillaries with which they were interlaced is brought
more clearly into view, as was pointed out by Rainey ; and likewise, accord-
ing to Henle, narrow bands, which he regards as formed of connective tissue,
are to be seen crossing the spaces.
JORIGIN OF THE BILIAEY DUCTS.
875
Commencements of the Ducts. — The smallest bile-ducts which are satisfac-
torily known, ramify between the lobules along with the interlobular blood-
vessels : but it is still a matter of discussion how the bile enters these ducts,
and what is the mode of its secretion.
Fig. 613.
Fig. 613.— DIAGRAMS SHOWING THE ARRANGEMENT OP THE BLOOD-VESSELS AND DUCTS
WITHIN AND BETWEEN THE LOBULES, ACCORDING TO KlERNAN. 2T°
In A, p, p, interlobular branches of the portal vein ; I, I, intralobular venous plexus,
connecting the portal veins (p, p) with the intralobular vein (A) in the centre, which is
the commencing branch of the hepatic vein ; in B, d} d are two branches of the hepatic
duct, which is supposed to commence in a plexus situated towards the circumference of
the lobule marked b, b, called by Kiernan the biliary plexus. Within this is seen the
central part of the lobule, containing branches of the intralobular (hepatic) vein.
Kiernan described the smallest biliary ducts as commencing within the
lobules by numerous ramifications in the form of a close network, which
he was only able to inject in the outer part of each lobule. Since the
discovery of the hepatic cells, however, it has been very generally supposed
Fig. 614.
Fig. 614. — VIEW OF SOME OP THE SMALLEST BILIARY DUCTS ILLUSTRATING BEALE'S
VIEW OP THEIR RELATION TO THE BILIARY CELLS (from Kolliker after Beale). ~
The drawing is taken from an injected preparation of the pig's liver.
a, small branch of an interlobular hepatic duct ; b, smallest biliary ducts ; c, portions
of the cellular part of the lobule in which the cells are seen within tubes which com-
municate with the finest ducts.
876 THE LIVER.
that, the cells being placed closely together, the bile either passes by irre-
gular interstices between them, or from one cell to another, to reach the
smallest ducts at the circumference of the lobules.
Beale, who has investigated the subject with great care, believes that he
has succeeded in demonstrating the existence of a basement membrane in-
closing, in a plexus of tubes, the intralobular rows or columns of hepatic
cells. This basement membrane, he conceives, lines the interstices between
the capillary blood-vessels forming the intralobular plexus ; and he states
that, although in the adult it becomes so closely incorporated with the walls
of the blood-vessels that it is scarcely to be demonstrated as a distinct struc-
ture, yet, in the foetus, the walls of these tubes and those of the vessels are
quite distinct. The minute ducts are considered by Beale to be directly
continuous with this tubular network : but the tubules containing the
hepatic cells, being T^ctli of an inch in diameter, and the smallest ducts
-g-J^th or less, there is a great difference in their size ; this difference, he
holds, however, is only similar to that which is found, in some other
glandular organs, between the proper secreting cavity and the ductal
Kolliker has become convinced of the correctness of Beale's account from
an examination of his preparations. Heule believes that the iuterlobular
bile-ducts are completely shut off from the cellular substance of the lobules,
which was the theory proposed by Handfield Jones ; and he suggests that
the hepatic cells are entirely engaged in the amyloid function of the liver,
and unconnected with the biliary secretion.
According to such views as those before stated, the anastomosing net-
work of ducts described by Kiernan would be regarded as artificial pas-
sages between the cells, formed by the force of injection ; and there is no
doubt that passages of that sort may be made. In recent years, however,
Budge, Andrejewic, Hyrtl, Frey, and other observers have succeeded in
displaying by injection of the cellular substance of the lobules a network of
fine canals of cylindrical form and regular diameter, and having therefor.',
a character which cannot be explained on the supposition that they arc
irregular interspaces of accidental origin. The apparent improbability of
the ducts of a secreting gland taking origin in minute tubes destitute of
epithelium, and external to secreting cells, has led to great opposition to
the view that the ducts in question are really bile-ducts ; and Reichert has
suggested that they are lymphatics : but a set of researches have sub-
sequently been published which invest the theory that the bile-duct*
begin within a fine intralobular plexus, with additional weight. Chrzon-
szczewsky, pursuing a method of experimenting by what may be called the
natural injection of colouring matter into the vessels of living animals, by
which he had previously succeeded in colouring the tubes and vessels of the
kidney, sought for a colouring matter which, when introduced into the
blood, would be eliminated in part by the bile without dyeing the textures
indiscriminately ; and, after numerous failures, he at last found one sub-
stance with the requisite properties, — viz., the sulpho-indigotate of soda
(in use under the name of " indigo-carmine "). A saturated watery solu-
tion of this substance was introduced, in repeated doses, into the circulation
of dogs and sucking-pigs, by the jugular vein ; and in an hour and a half
afterwards, while the animals were still living, the blood-vessels were either
washed out with chloride of potassium introduced by the portal vein, or
they were injected with gelatine and carmine. In specimens prepared in
this way, Chrzonszczewsky obtained an extremely fine network of gall-ducts
STRUCTURE OF THE BILIARY DUCTS.
877
throughout each lobule, injected blue, while the intervening cells remained
free from colour. These canals he describes as of regular diameter, without
increase of size where they anastomose, and by teasing he obtains portions
of them with distinct walls standing out free from the cells : by warming
the section to 113° Fah., the blue colour is destroyed while the canals still
remain visible. By killing the animals sooner after the injection, the
blue colouring matter was found within the hepatic cells, thus demonstrating
that it was through their agency that the canals were filled. Further expe-
riments were made in animals in which the portal vein and hepatic artery
had been tied, and the result obtained was that, when the hepatic artery
Fig. 615. — Two SMALL FRAGMENTS OP HEPATIC LOBULES, OF Fig. 615.
WHICH THE SMALLEST INTERCELLULAR BlLIARY DtJCTS WEEK
FILLKD WITH COLOURING MATTKR DURING LlFE, HIGHLY
MAGNIFIED (from Chrzonszczewsky).
In A, the hepatic cells have been separated, and the inter-
cellular ducts, «, are seen not only passing between them,
but also in part projecting free ; in this preparation the
colour was discharged by heat : in B, the colouring matter
remains in the ducts, and the cells are more closely con-
nected together.
had been tied, the peripheral parts of the lobules
showed the blue canals, while the centre of each
was left colourless ; and that, when the portal vein
had been tied, the reverse effect was produced ;
the centre of each lobule showing blue canals, while
in the intervening spaces only larger ducts were
seen. It is worthy of remark that the appearance
of fibres crossing the capillary spaces observed by
Henle in sections washed with alkali, might very
well be due to such canals as those described by
Budge, Chrzonszczewsky, and others.
Structure of the ducts. — The bile-ducts have strong distensible areolar
coats, containing abundant elastic tissue, and their mucous membrane is
lined with columnar epithelium. The minute ramifications between the
lobules have walls of a more homogeneous nucleated tissue, but the lining of
columnar epithelium is still found in them (Henle). The mucous membrane
of those which are less minute presents numerous openings, which are scat-
tered irregularly in the larger ducts, but in the subdivisions are arranged in
two longitudinal rows, one at each side of the vessel. These openings were
formerly supposed to be the orifices of mucous glands ; but, while the main
ducts are studded with true mucous glands of lobulated form and with
minute orifices, the larger openings now referred to belong, as was pointed
out by Theile, to sacs and ramified tubes which occasionally anastomose,
and may be studded all over with caecal projections. Sappey and Henle,
who have made these processes the subject of special investigation, find
that they are so numerous as sometimes to conceal the parent tube, and
on this Henle bases his suggestion (System. Anat.) that they are engaged in
the secretion of the bile.
Aberrant biliary ducts. — In the duplicature of the peritoneum forming
the left lateral ligament of the liver, and also in the two fibrous bands
which sometimes convert the fossa for the vena cava and the fissure of the
umbilical vein into canals, there have been found biliary ducts of considerable
878 THE LIVER.
size which are not surrounded with lobules. These aberrant ducts, as they
might be called, were described by Ferreiu and by Kieriian ; they anastomose
together in form of a network, and are accompanied by branches of the
vena portse, hepatic artery, and hepatic vein.
Structure of the gall-bladder. — Besides the peritoneal investment, the walls
of the gall-bladder are formed of two distinct layers of tissue constituting its
areolar or fibrous and its mucous coats.
The areolar coat is strong, and consists of bands of dense shining white
fibres, which interlace in all directions. These fibres resemble those of
areolar tissue. In quadrupeds recently killed the gall-bladder contracts on
the application of a stimulus ; and in the larger species, as well as in man,
muscular fibres of the plain variety have been found mingled with those of
the areolar coat. These fibres have principally a longitudinal direction, but
some run transversely. Their nuclei are indistinct. The areolar coat forms
the framework of the organ, and supports the larger bloodvessels and lym-
phatics.
The mucous coat, which is generally strongly tinged of a yellowish-brown
colour with bile, is elevated upon its inner surface into very numerous small
ridges, which, uniting together into meshes, leave between them depressions
of different sizes and of various polygonal forms. This structure gives to the
interior of the gall-bladder an areolar aspect, which is similar to what is
seen on a smaller scale in the vesiculae seminales. These areolar intervals
become smaller towards the fundus and neck of the gall-bladder ; and at
the bottom of the larger ones, other minute depressions, which may be seen
with a magnifying lens, apparently lead into numerous mucous recesses or
follicles. The whole of the mucous membrane is covered by columnar
epithelium, and it secretes an abundance of viscid mucus.
At the places where the neck of the gall-bladder curves on itself, there
are strong folds or projections of its mucous and areolar coats into the
interior.
In the cystic duct, the mucous membrane is elevated internally in a sin-
gular manner into a series of crescentic folds, which are arranged in an
oblique direction, and succeed closely to each other, so as to present very
much the appearance of a continuous spiral valve. When distended, the
outer surface of the duct appears to be indented in the situation of these
folds, and dilated or swollen in the intervals, so as to present an irregularly
sacculated or twisted appearance. It is of importance to note the influence
of this valve in causing the retention of biliary concretions in the gall-
bladder.
Among the monographs which give an account of the structure of the
liver, the following may be specially mentioned : — Kiernan, in Phil. Trans-
actions, 1833 ; Theile, in Wagner's Handworterbuch d. Physiologie, p. 308 ;
Rainey on the Capillaries of the Liver, in Microsc. Journal, I. p. 231 ;
Handfield Jones, in Phil. Transactions, 1849 and 1853; Budge, in Miiller's
Archiv, 1850 ; Beale, Lectures in Medical Times and Gazette, 1856, and
"On some points in the Anatomy of the Liver," in Philos. Trans. 1856 ;
Chrzonszczewsky, in Virchow's Archiv, XXXV. p. 153, 1866 ; Frey, in
Zeitsch. f. Wissensch. Zoologie, March, 1866.
THE BILE.
The bile, as it flows from the liver, is a thin greenish yellow fluid ; but that which
remains in the gall-bladder becomes darker, more viscid, and ropy. It contains as
adventitious particles mucus and epithelium corpuscles, but no hepatic cells. The
DEVELOPMENT OF THE LIVER. 879
specific gravity of the bile is from 1-026 to T030. It has a sweetish bitter taste, and
an alkaline reaction. It is a saponaceous compound, containing the following ingre-
dients : — water, mucus, colouring matters (composed, according to Berzelius, of a
yellow substance named cholepyrrhine, a brown substance named bilifulvine, and a
green matter or biliverdine), fatty acids, viz., the margaric and oleic, combined with
soda, free fat, cholesterine, salts, and, lastly, the most important ingredient of the
bile, namely, the proper biliary matter, which consists, according to Strecker and
Lehmann, of two " conjugated acids," formed by the union of one acid, the Choleic,
in two isomeric forms (the cholic and choloidic acids of some authors) with Glycin
and Taurin respectively. Thus the Glycocholic and Taurocholic acids are formed,
each of them consisting principally of carbon and hydrogen, but both containing
nitrogen, and the latter a considerable quantity of sulphur. They are combined
with soda, but are very readily decomposed, giving rise to ammoniacal and other
compounds. Of these two acids the glycocholic is the most important. The bile-
pigment affords the most characteristic tests for the detection of biliary matter.
DEVELOPMENT AND FCETAL PECULIARITIES OF THE LIVER.
The liver begins to be formed at a very early period of foetal life. Both in the
mammal, as seen by Bischoff, and in the bird, as Kemak's researches show, it begins
in the form of two blind processes from the intestinal tube, immediately beneath the
dilatation for the stomach. According to Kemak, these processes involve both the
epithelial and the fibrous layers of the intestine; and the fibrous layer, rapidly growing,
involves the omphalo-mesenteric vein and forms the outline of the liver : meanwhile
the internal structure takes origin by the growth of anastomosing cylinders of cells
from the epithelial layer, and of tufts of blood-vessels.
Fig. 616.— EARLY Cox- Fi 616
DITION OP THE LlVER
IN THE CHICK ON THE
THIRD DAT OP INCU-
BATION (from J. M til-
ler), i?
1, the heart, as a sim-
ple curved tube ; 2, 2,
the intestinal tube ; 3,
conical protrusion of the-
coat of the commencing
intestine, on which tbe
blastema of the liver (4) is
formed; 5, portion of the
layers of the germinal
membrane, passing into
the yolk-sac.
The gall-bladder, according to some authors, is developed as a branch or diverticulum
from the bile-duct outside the liver; but Meckel describes it as arising in a deep
notch in the substance of the gland. It is at first tubular, and then has a rounded
form. The alveoli in its interior appear about the sixth month. At the seventh
month it first contains bile. In the foetus its direction is more horizontal than in the
adult.
Size. — In the human foetus, at the third or fourth week, the liver is said to con-
stitute one-half of the weight of the whole body. This proportion gradually decreases
as development advances, until at the full period the relative weight of the foetal liver
to that of the body is as 1 to 18.
In early foetal life, the right and left lobes of the liver are of equal, or nearly equal,
size. Later, the right preponderates, but not to such an extent as after birth. Imme-
diately before birth the relative weight of the left lobe to the right is nearly as
1 to 1-6.
Position. — In consequence of the nearly equal size of the two lobes, the position
of the foetal liver in the abdomen is more symmetrical than in the adult. In the
very young foetus it occupies nearly the whole of the abdominal cavity; and at
880 THE LIVER.
the full period it still descends an inch and a half below the margin of the thorax,
overlaps the spleen on the left side, and reaches nearly down to the crest of the ilium
on the right.
Form, Colour, &c. — The foetal liver is considerably thicker from above down-
wards than that of the adult. It is generally of a darker hue. Its consistence and
specific gravity are both less than in the adult.
Blood- Vessels. — The blood-vessels of the fcetal liver present several important pecu-
liarities, with which, indeed, those previously mentioned are more or less connected.
Up to the moment of birth, the greater part of the blood returned from the placenta
by the umbilical vein passes through the liver of the foetus before it reaches the
heart ; while a smaller part is transmitted more directly to the right auricle.
During foetal life, the umbilical vein runs from the umbilicus along the free margin
of the suspensory ligament towards the anterior border and under surface of the
liver, beneath which it is lodged in the umbilical fissure, and proceeds as far as
the transverse fissure. Here it divides into two branches ; one of these, the smaller
of the two, continues onward in the same direction, and joins the vena cava; this
is the ductus venosus, which occupies the posterior part of the longitudinal fissure,
and gives to it the name of the fossa of the ductus venosus. The other and larger
branch (the trunk of the umbilical vein) turns to the right along the transverse or
portal fissure, and ends in the vena portse, which, in as much as it proceeds from the
veins of the digestive organs, is in the foetus comparatively of small dimension*.
Moreover, the umbilical vein, as it lies in the umbilical fissure, and before it joins the
vena portae, gives off some lateral branches, which enter the left lobe of the liver.
It also sends a few branches to the square lobe and to the lobe of Spigelius.
Fig. 617. Fig. 617. — UNDER SURFACE OF THE
F(ETAL LlVER, WITH ITS GREAT
BLOOD-VESSELS, AT THE FULL
PERtOD. f
The rounded outline of the organ,
and the comparatively small differ-
ence of size between its two lobes,
are seen : a, the umbilical vein,
lying in the umbilical fissure, and
turning to the right side at the
transverse fissure (o), to join the
vena portse (p) : the branch marked
d, named the ductus venosus, con-
tinues straight on to join the vena
cava inferior (c) : a few branches of
the umbilical vein enter the sub-
stance of the liver at once ; g, the
gall-bladder.
The blood of the umbilical vein may therefore be considered as reaching the
ascending vena cava in three portions. Some is carried into it by the more direct
passage of the ductus venosus ; another, the principal portion, passes first through
the portal veins, and then through the hepatic veins ; whilst a third portion, supplied
by direct branches to the liver, is also returned to the cava by the hepatic veins.
Changes after birth. — Immediately after birth, at the cessation of the current
which previously passed through the umbilical vein, and on the establishment of an
increased circulation through the lungs, the supply of blood to the liver is diminished
by nearly two-thirds. The umbilical vein and ductus venosus become empty and con-
tracted, and soon afterwards they begin to be obliterated, and are ultimately converted
into the fibrous cords already described, — that one which represents the umbilical vein
constituting the round ligament of the liver. At the end of six days the ductus
venosus has been found to be closed ; but it sometimes continues open for several
weeks. That portion of the umbilical vein which supplied direct branches to the
liver remains open, though diminished in size, and, being in communication with
the leffc branch of the vena portse, continues afterwards to transmit blood to a part of
the liver from that vessel.
Concurrently with, and doubtless in some measure dependent on; the sudden
FORM AND RELATIONS OF THE PANCREAS. 881
diminution in the quantity of blood supplied to the liver after birth, this organ
appears at first to become absolutely lighter; and, according to some data, this
decrease of weight is not recovered from until the conclusion of the first year. After
that period, the liver, though it increases in size, grows more slowly than the body,
so that its relative weight in proportion to the body, which was 1 to 18 just before
birth, becomes gradually less and less. At about five or six years of age it has
reached the proportion maintained during the rest of life, viz. 1 to 36.
The relative weight of the left lobe to that of the right (which, as above stated, is
about 1 to 1.6 immediately before birth) undergoes a subsequent diminution. Thus,
at a month old, it has been found to be as 1 to 3, and in after-life the proportion is
generally 1 to 4 or 5.
THE PANCREAS.
The pancreas is a long, narrow, flattened gland, larger at one end than
at the other, and lying deeply in the cavity of the abdomen, immediately
behind the stomach, and opposite the first lumbar vertebra. Its larger end,
the head, turned to the right, is embraced by the curvature of the duodenum,
whilst its left or narrow extremity, the tail, reaches to a somewhat higher
level, and is in contact with the spleen. It extends across the epigastric
into both hypochondriac regions.
The right or large end of the pancreas is bent from above downwards, and
accurately fills the curvature of the duodenum, to which it is closely adhe-
rent. The lower extremity of this curved portion passes to the left, behind
Fig. 618.
Fig. 618. — VIEW ov THE PANCREAS AND SURROUNDING ORGANS. £
In this figure, which is altered from Tiedemann, the liver and stomach are turned
upwards to show the duodenum, the pancreas, and the spleen : I, the under surface of
the liver ; g, gall-bladder ; /, the common bile-duct, formed by the union of the cystic
duct from the gall-bladder, and the hepatic duct coming from the liver ; o, the
cardiac end of the stomach, where the oesophagus enters ; «, under surface of the
stomach ; p, pyloric end of the stomach ; d, duodenum ; h, head of the pancreas ; t, tail,
and i, body of that gland ; the substance of the pancreas is removed in front, to show the
pancreatic duct (e) and its branches ; r, the spleen ; v, the hilus, at which the blood-
vessels enter ; c, c, crura of the diaphragm ; n, superior mesenteric artery ; a, aorta.
the superior mesenteric vessels, forming the posterior wall of a sort of
canal in which they are enclosed. This part of the gland is sometimes
marked off from the rest, and is then named the lesser pancreas.
The pancreas varies considerably, in different cases, in its size and weight. It is
usually from 6 to 8 inches long, about 1^ inch in average breadth, and from half an
3 M
882 THE PANCREAS.
inch to an inch in thickness, being thicker at its head and along its upper border than
elsewhere. The weight of the gland, according to Krause and Clendenning, is
usually from 1\ oz. to 3| oz. ; but Meckel has noted it as high as 6 oz., and Soemmer-
ring as low as 1| oz.
The anterior surface of the pancreas is covered with the posterior wall of
the sac of the omentum, and is concealed by the stomach, which glides upon
it. The posterior surface is attached by areolar tissue to the vena cava, the
aorta, the superior inesenteric artery and vein, the commencement of the
vena portse, and the pillars of the diaphragm, all of which parts, besides
many lymphatic vessels and glands, are interposed between it and the upper
lumbar vertebrae : to the left of the vertebral column it is attached simi-
larly to the left suprarenal capsule and kidney and to the renal vessels. Of
the large vessels situated behind the pancreas, the superior inesenteric artery
and vein are embraced by the substance of the gland, so as sometimes to be
enclosed in a complete canal, through which they pass downwards and for-
wards, and then emerge from beneath the lower border of the pancreas,
between it and the termination of the duodenum. The coeliac axis is above
the pancreas ; and in a groove along the upper border of the gland are placed
the splenic artery and vein, the vein pursuing a straight, and the artery a
tortuous course, and both supplying numerous branches to the pancreas, the
narrow extremity of which is thus attached to the inner surface of the spleen.
The head of the pancreas, embraced by the inner curved border of the duo-
denum, is attached more particularly to the descending and transverse por-
tions of that intestine, beyond which it projects somewhat both in front and
behind. The ductus communis choledochus passes down behind the head
of the pancreas, and is generally received into a groove or canal in its
substance.
Structure. — The pancreas belongs to the class of conglomerate glands. lu
its general characters, and also in its intimate structure, which is racemose, it
closely resembles the salivary glands, but it is somewhat looser and softer in
its texture. It consists of numerous lobes and lobules, of various sizes,
held together by areolar tissue, blood-vessels, and ducts. The lobules,
aggregated into masses, are rounded or slightly flattened at the sides, so as
to be moulded or adjusted compactly to each other ; their substance is of a
reddish cream-colour, and the arrangement of the commencing ducts and
vessels is similar to that in the lobules of the parotid gland, which has been
already described (p. 816).
The principal excretory duct, called the pancreatic duct or canal of
Wirsung (by whom it was discovered in the human subject in 1642), runs
through the entire length of the gland, from left to right, buried completely
in its substance, and placed rather nearer its lower than its upper border.
Commencing by the union of the small ducts derived from the groups of
lobules composing the tail of the pancreas, and receiving in succession at
various angles, and from all sides, the ducts from the body of the gland,
the canal of Wirsung increases in size as it advances towards the head of
the pancreas, where, amongst other large branches, it is usually joined by
one derived from that portion of the gland called the lesser pancreas.
Curving slightly downwards, the pancreatic duct Hhen comes into contact
with the left side of the ductus communis choledochus, which it accom-
panies to the back part of the descending portion of the duodenum. Here
the two ducts, placed side by side, pass very obliquely through the muscular
and areolar coats of the intestine, and terminate, as already described
(p. 868), on its internal mucous surface, by a common orifice, situated at
FORM AND RELATIONS OF THE SPLEEN. 883
the junction of the descending and horizontal portions of the duodenum,
between three and four inches below the pylorus. The pancreatic duct,
with its branches, is readily distinguished from the glandular substance,
by the very white appearance of its thin fibrous walls. Its widest part,
near the duodenum, is from 1 line to 1 J line in diameter, or nearly the size
of an ordinary quill ; but it may be easily distended beyond that size. It
is lined by a remarkably thin and smooth mucous membrane, which near
the termination of the duct occasionally presents a few scattered follicles.
Varieties. — Sometimes the pancreatic duct is double up to its point of entrance
into the duodenum ; and a still farther deviation from the ordinary condition is not
unfrequently observed, in which there is a supplementary duct, derived from the
lesser pancreas or some part of the head of the gland, opening into the duodenum by
a distinct orifice, at a distance of even one inch or more from the termination of the
principal duct. It sometimes occurs that the pancreatic duct and the common bile
duct open separately into the duodenum.
Vessels and Nerves.— Like the salivary glands, the pancreas receives its blood-
vessels at numerous points. Its arteries are derived from the splenic and from the
superior and inferior pancreatico-duodenal branches of the hepatic and superior
mesenteric. Its blood is returned by the splenic and superior mesenteric veins.
Its lymphatics terminate in the lumbar vessels and glands. The nerves of the
pancreas are derived from the solar plexus.
Development. — In its origin and development, the pancreas altogether resembles
the salivary glands. It appears a little earlier than these glands, in the form of a
small bud from the left side of the intestinal tube, close to the commencing spleen.
Secretion. — Like the saliva, the pancreatic juice is a clear colourless fluid, which
has diffused in it a few microscopic corpuscles ; it has an alkaline reaction, and
coagulates in white flakes when heated. The coagulum is caused by the presence of
an albuminoid substance — pancreatin — which, like salivin, has the property of con-
verting starch into sugar. The pancreatic juice contains likewise chlorides of sodium
and potassium, and phosphates of lime, soda, and magnesia. It readily undergoes
decomposition on exposure.
THE SPLEEN.
The spleen is a soft, highly vascular, and easily distensible organ, of a
dark bluish or purplish grey colour. It is situated in the left hypochon-
drium, at the cardiac end of the stomach, between that viscus and the dia-
phragm, and is protected by the cartilages of the ribs. It is the largest of
the structures termed ductless glands, and it is now generally admitted to
be intimately connected with the process of sanguification, and is most pro-
bably the seat of the formation of blood-corpuscles.
The shape of the spleen is irregular and somewhat variable : it forms a
compressed oval mass, placed nearly vertically in the body, and having two
faces, one external, convex, and free, which is turned to the left, the other
internal and concave, which is directed to the right, and is applied to the
cardiac end or great cul-de-sac of the stomach : it also presents an anterior
sharper and a posterior blunter margin.
The convex face of the spleen, smooth and covered by the peritoneum, is
in contact with the under surface of the left side of the diaphragm, and
corresponds with the ninth, tenth, and eleventh ribs. The internal concave
face is divided by a vertical fissure, named the hilus, into an anterior and
posterior portion, both covered with peritoneum, continued round the bor-
ders from the convex surface. The anterior of these two portions is the
larger, and is closely applied to the stomach ; the posterior is in apposition
with the left pillar of the diaphragm and left suprarenal capsule. The
anterior border of the spleen is thinner than the posterior, and is often
3 M 2
884 THE SPLEEN.
slightly notched, especially towards the lower part. The lower end is pointed,
and is in contact with the left end of the arch of the colon, or with the
transverse ineso-colon. The position of the hilus corresponds with the line
of attachment of the gastro-spleuic omentuin. Along the bottom of this
fissure are large openings or depressions, which transmit blood-vessels, with
lymphatics and nerves, to and from the interior of the organ. In some
cases there is no distinct fissure, but merely a row of openings for the
vessels ; and in others the situation of the hilus is occupied by a longitu-
dinal ridge, interrupted by the vascular orifices. The peritoneal connections
of the spleen have been already described (pp. 827 and 830). A portion
of variable extent behind the hilus, and towards its lower end, will usually
be observed deriving its peritoneal covering from the sac of the omentum.
The spleen varies in magnitude more than any other organ in the body ; and this
not only in different subjects, but in the same individual, under different conditions,
sometimes appearing shrunk, and at others being much distended. On this account
it is difficult or impossible to state what are its ordinary weight and dimensions: in
the adult it measures generally about 6 or 5\ inches from the upper to the lower end,
3 or 4 inches from the anterior to the posterior border, and 1 or 1J inch from its
external to its internal surface ; and its usual volume, according to Krause, is from 9|
to 15 cubic inches. In the greater number of a series of cases examined by Eeid, its
weight ranged from 5 to 7 oz. in the male, and was somewhat less in the female ; but
even when perfectly free from disease, it may fluctuate between 4 and 10 ounces. Gray
states that the proportion of the spleen to the weight of the adult body varies from
1 : 320 to 1 : 400. In the foetus the proportion is as 1 : 350. After the age of forty the
average weight gradually diminishes, so that in old age the weight of the spleen is to
that of the body as 1 : 700 (H. Gray). The specific gravity of this organ, according to
Haller, Scemmerring, and Krause, is about 1'060. In intermittent and some other
fevers the spleen is much distended and enlarged, reaching below the ribs, and often
weighing as much as 1 8 or 20 Ibs. In enlargement and solidification it has been
known to weigh upwards of 40 Ibs. ; and it has been found reduced by atrophy to the
weight of two drachms.
Small detached roundish nodules are occasionally f »und in the neighbourhood of
the spleen, similar to it in substance. These are commonly named accessory or
supplementary spleens (splenculi ; lienculi). Of these one or two most commonly
occur, but a greater number, and even up to twenty-three, have been met with.
They are small rounded masses, varying from the size of a pea to that of a walnut.
They are usually situated near the lower end of the spleen, either in the gastro-splenic
omentum, or in the great omentum. These separate splenculi in the human subject
bring to mind the multiple condition of the spleen in some animals, and also the
deeper notching of the anterior margin of the organ which sometimes occurs in man.
Structure. — The spleen has two membranous investments — a serous coat
derived from the peritoneum, and a special albugiueous fibre-elastic tunic.
The substance of the organ, which is very soft aud easily lacerated, is of a
dark reddish-brown colour, but acquires a bright red hue on exposure to
the air. Sometimes, however, the substance of the spleen is paler, and has
a greyish aspect. It also varies in density, being occasionally rather solid,
though friable. The substance of the organ consists of a reticular frame-
work of whitish elastic bands or trabcculce, of an immense proportion of
blood-vessels, the larger of which run in elastic canals, and of a peculiar
intervening pulpy substance, besides lymphatic vessels and nerves.
The peritoneal coat is thin, smooth, and firmly adherent to the elastic
tunic beneath, but it may be detached by careful dissection, commencing at
the borders of the hilus. It closely invests the surface of the organ, except at
the places of its reflection to the stomach and diaphragm, and at the hilus.
The proper tunic, much thicker and stronger than the serous, is whitish in
MIXUTE STRUCTUEE OF THE SPLEEX.
885
colour and highly elastic. It cannot be raised from the spleen, because it is
bound down by the trabeculae of the substance, with the superficial bands
of which it is continuous. Along the hilus this coat is reflected into the
interior of the spleen, in the form of elastic sheaths or canals, which sur-
round or include the large blood-vessels and nerves, and their principal
branches. These sheaths ramify with the vessels which they include, and
their finer subdivisions are continuous with the trabecular structure. The
arrangement of the elastic sheaths and trabeculse may be easily displayed by
pressing and washing out the pulp from a section of the spleen ; and then
they are seen to form a close reticulation through the substance. Thus,
Fig. 619.
Fig. 619.— VERTICAL SEC-
TION OF A SMALL SUPER-
FICIAL PORTION OF THE
HUMAN SPLEEN (from
Kolliker). 3'g
A, peritoneal and fibrous
covering ; b, trabeculse ;
cc, Malpighian corpuscles,
in one of which an artery
is seen cut transversely, in
the other longitudinally ;
d, injected arterial twigs;
e, spleen-pulp, with the
venous spaces and the
finest spleen - tissue, the
venous spaces all com-
pletely full of blood and
somewhat wider than na-
tural.
the proper coat, the
sheaths of the ves-
sels, and the trabeculse,
all of a highly elastic
nature, constitute a distensible framework, which contains in its inter-
stices or areolse the vessels and the red pulpy substance of the spleen.
Fig. 620.— SECTION OF HARDENED
SPLEEN-SUBSTANCE (from Kol-
liker after a preparation by
Billroth). 3*8
The spleen had been hardened
in chromic acid and alcohol, a,
Malpighian bodies, one of them
having an artery dividing into
three twigs within, the other with
two arteries cut through ; 6, tra-
beculse ; c, artery ; in the re-
maining paits the clear spaces are
the capillary veins of Billroth,
the darker ones are the smallest
trabeculse of the spleen-substance.
These fibrous structures are
all composed of interlaced
bundles of areolar tissue mixed with a large amount of fine elastic tissue.
In addition to these elements, in the spleen of the pig, the dog, and the
886 THE SPLEEN".
cat, and to a smaller extent in that of the ox and sheep, there has been
found an abundant admixture of plain muscular fibres, resembling those of
the middle coat of arteries. Meissner and W. Miiller affirm that they also
find muscular fibres in the trabeculse and fibrous coat of the human spleen ;
but the existence of such fibres is denied by other observers. The elasticity
of the fibrous coat and trabeculae, together with whatever amount of mus-
cularity they may possess, renders the spleen capable of the great and
sudden alterations in size to which it is subject.
The pulp of the spleen is of a dark reddish-brown colour : when pressed
out from between the trabeculse it resembles grumous blood, and, like that
fluid, it acquires a brighter hue on exposure to the air. This pulpy eub-
stance lies altogether outside the veins, between the branches of the venous
plexus. As shown by the microscope, it consists chiefly of numerous
rounded granular bodies, which have a reddish colour, and are about the
size of the blood corpuscles. Their cohesion is very slight, and the termi-
nal tufts of the arterial system of vessels are spread out amongst them. In
examining the substance of the spleen, elongated caudate corpuscles are
seen in rather large numbers. And besides these there are round nucleated
cells, and free nuclei. There are also large cells, some of which are nucle-
ated, and others not, but both of which contain blood-corpuscles in various
states of change.
The splenic artery and vein, alike remarkable for their great proportionate
size, having entered the spleen by six or more branches, ramify in its inte-
rior, enclosed within the elastic sheaths already described. The smaller
branches of the arteries run along the trabeculse, and terminate in the
proper substance of the spleen in small tufts of capillary vessels arranged
in pencils. These are supported by fine microscopic trabeculse which run
through the pulp in all directions. The main branches of artery which
enter the spleen appear to have few or no anastomoses within the substance
of the organ, for it has been justly remarked that, if one of them be
injected, the material of injection will return by the corresponding vein
before spreading to other parts of the spleen : and it only returns by
the vein after injection of the pulp. The veins, which greatly exceed the
arteries in size, anastomose frequently together, so as to form a close venous
plexus, placed in the intervals between the trabecuJae, and supported by
them. There is still great difference of opinion as to the manner in which
Fig. 621. Fig. 621. — A SMALL FRAGMENT OP A PREPARED
SPLEEN UNRAVELLED (from Kolliker). 5J5
a, finest reticulum ; b, transversely cut
capillary veins which have lost their epithelium;
C, veins in which the epithelium is more or less
preserved ; d, longitudinal section of the same ;
e, a capillary vessel lying in the finest splenic
tissue,
the arteries and veins are connected.
According to Gray, the capillaries
traverse the pulp in all directions, and
terminate either directly in the veins,
or open into lacunar spaces, from which
the veins originate. Billroth and Kolliker admit only the direct termina-
tion in veins ; Stieda and W. Miiller maintain that a network of inter-
cellular passages intervenes.
MALPIGHIAX CORPUSCLES OF THE SPLEEN.
887
Malpighian corpuscles. — On closely inspecting the surface of a section of
the spleen, a number of light-coloured spots of variable size are generally
seen. For the most part these are evidently the ends of divided trabeculae
or blood-vessels ; but in the ox, pig, sheep, and some other animals, and also
in the human subject, there are found distinct whitish vesicular-looking
bodies, attached to the trabeculse which support the small arteries, and
imbedded, in groups of six or eight together, in the dark red substance of
the spleen. These small vesicular bodies, the Malpighian corpuscles of the
spleen, are capsules, varying in diameter from -^jth to -g-^th of an inch, and
consisting of two coats, the external of which is apparently continuous with
the trabecular tissue supporting the arteries. They are filled with a soft,
whitish, semi-fluid matter, which contains microscopic globules, resembling,
except in colour, those composing the red pulp of the spleen. It may ba
remarked, that both these kinds of globules are very like the chyle-corpuscles.
The vesicular bodies are attached in groups to minute arterial branches ; in
some of the lower animals they are sessile, but in the human spleen they are
pedunculated. In all cases it is established that they are expansions of the
sheaths of the arteries ; those which are sessile are placed usually in the
angle of division of two arteries, and are formed by expansion on one side
Fig. 622.
Fig. 622. — MALPIGHIAN CORPUSCLES OP
THE DOG'S SPLEEN (from Kolliker). ^
The figure shows a portion of a small
artery, to one of the twigs of which the
Malpighian corpuscles are attached.
only of the vessels on which they
are placed ; those which are pe-
dunculated are pierced by the
artery on which they are placed,
the expanded sheath having been
diffused, as it were, in the cap-
sule, round the vessel (Stieda and
Henle). Their walls pass gra-
dually into the pulp on the out-
side, and on the inside into the
contents of the follicle (Busk and
Huxley). Capillaries likewise are
found within them.
The lymphatic vessels of the spleen,
according to Cruikshank and Mascagni,
form a superficial and a deep set. The superficial set appear as a network beneath the
serous coat, receive occasional branches from the substance of the spleen, and run
towards the hilus. The deep lymphatics accompany the blood-vessels, and emerge
with them at the hilus, whence, communicating with the superficial set, they proceed
along the gastro-splenic omentum to the neighbouring lymphatic glands : the mode
in which they commence iu the spleen is unknown. The lymphatics of the human
spleen, at least the superficial set, are allowed by all to be very difficult to inject.
But even in the domestic animals, in which the process is usually more successful,
recent observers have not been so fortunate as Cruikshank and Mascagni.
The splenic nerves, derived from the solar plexus, surround and accompany the
splenic artery and its branches. They have been traced by Remak deeply into the
interior of the organ.
888 ORGANS OF RESPIRATION.
The following works on the spleen may be referred to : — Gray, Structure and Use
of the Spleen, 1854; Sanders, in Goodsir's Annals; Busk and Huxley on the
Malpighian Bodies, in the Sydenham Society's translation of Kolliker's Histology ;
also Huxley in Micr. Jour., ii. p. 74; Billroth, in Zeitschr. f. Wissensch. Zool., xi.
p. 325 ; W. Miiller, Ueber d. fein. Bau der Milz, 1865. Stieda, in Virchow's Archiv,
xxiv. p. 540, an abstract of which is given in Medico-Chir. Rev., October, 1862.
Development. — The spleen appears in the foetus, about the seventh or eighth week,
on the left side of the dilated part of the alimentary tube or stomach, and close to the
rudiment of the pancreas. By the tenth week it forms a distinct lobulated body
placed at the great end of the stomach. After birth it increases rapidly in size ; and
in a child a few weeks old, it has attained the same proportional weight to the body
as in the adult. This organ is peculiar to vertebrate animals.
ORGANS OF RESPIRATION.
THE organs of respiration consist of the thorax (already described), the
larynx, the trachea, and the lungs. The larynx, affixed to the upper end of
the windpipe, is not only the entrance for air into the respiratory organs from
the pharynx, but also the organ of voice, and will be described later.
THE TRACHEA AND BRONCHI.
The trachea or windpipe, the common air-passage of both lungs, is an
open tube which commences at the larynx above, and divides below into
two smaller tubes, the right and the left bronchus, one for each lung.
The trachea is placed in the middle plane of the body, and extends from
the lower border of the cricoid cartilage of the larynx, on a level with the fifth
cervical vertebra in the neck, to a place opposite the third dorsal vertebra in
the thorax, where it is crossed in front by the arch of the aorta, and at or
immediately below that point it bifurcates into the two bronchi. It usually
measures from four inches to four inches and a half in length, and from
three-quarters of an inch to one inch in width ; but its length and width
are liable to continual variation, according to the position of the larynx and
the direction of the neck ; moreover, it usually widens a little at its lower
end, and its diameter is always greater in the male than in the female. In
front and at the sides the trachea is rendered cylindrical, firm, and resistant
by a series of cartilaginous rings ; these, however, are deficient behind, so
that the posterior portion is flattened and entirely membranous.
The trachea is nearly everywhere invested by a loose areolar tissue,
abounding in elastic fibres, and it is very movable on the surrounding parts.
Both in the neck and in the thorax, it rests behind against the oesophagus,
which intervenes between it and the vertebral column, and towards its lower
part projects somewhat to its left side. The recurrent laryngeal nerves
ascend to the larynx on each side in the angle between these two tubes.
In the neck the trachea is situated between the common carotid arteries ;
at its upper end it is embraced by the lateral lobes of the thyroid body, the
middle part or isthmus of which lies across it just below the larynx. It
is covered in front by the sterno-thyroid and sterno-hyoid muscles, between
which, however, there is left an elongated lozenge-shaped interval in the
middle line : this interval is covered in by a strong process of the deep
cervical fascia, while, more superficially, another layer not so strong crosses
between the sterno-mastoid muscles. The inferior thyroid veins and the
arteria thyroidea ima, when that vessel exists (p. 340), also lie upon its
anterior surface ; whilst at the root of the neck, in the episternal notch, the
innominate artery and the left carotid pass obliquely over it as they ascend
to gain its sides.
THE TRACHEA AND BROXCHI.
In the thorax, the trachea is covered by the first piece of the sternum,
together with the sterno- thyroid and sterno-hyoid muscles ; lower down, by
the left innominate vein, then by the commencement of the innominate
artery and left carotid, which pass round to its sides ; next by the arch of
the aorta and the deep cardiac plexus of nerves, and, quite at its bifurcation,
by the extremity of the pulmonary artery, where it divides into its right and
left branches. Placed between the two pleurae, the trachea is contained in
the posterior mediastinum, and has on its right side the pleura and pneumo-
gastric nerve, and on the left, the left carotid artery, the pneumo-gastric and
its recurrent branch, together with some cardiac nerves.
Fig. 623.
Fig. 623.— OUTLINE SHOWING THE GENE-
RAL FORM OF THE LARYNX, TRACHEA,
AND BRONCHI, AS SEEN FROM BEFORE, i
7i, the great cornu of the hyoid bone ; e,
epiglottis ; t, superior, and t', inferior
cornu of the thyroid cartilage ; c, middle
of the cricoid cartilage ; t r, the trachea,
showing sixteen cartilaginous rings ; 6, the
right, and &', the left bronchus.
The right and left bronchi com-
mence at the bifurcation of the
trachea and diverge to reach the cor-
responding lungs. They differ from
each other in length, width, direc-
tion, and connection with other
parts. The right bronchus, wider
but shorter than the left, measuring
about an inch in length, passes out-
wards almost horizontally into the
root of the right lung on a level
with the fourth dorsal vertebra : it
is embraced above by the vena azygos,
which hooks forwards over it, to end
in the vena cava superior ; the right
pulmonary artery lies at first below
it and then in front of it. The left
bronchus, smaller in diameter, but
longer than the right, being nearly
two inches in length, inclines ob-
liquely downwards and outwards
beneath the arch of the aorta to
reach the root of the left lung,
which it enters on a level with the
fifth dorsal vertebra, that is, about
an inch lower than the right bron-
chus. The left bronchus crosses in
front of the oesophagus and descend-
ing aorta : the arch of the aorta turns backwards and to the left over
it, and the left pulmonary artery lies first above it and then on its
anterior surface. The remaining connections of each bronchus, as it lies
within the root of the corresponding lung, and the mode in which it sub-
divides there into bronchia, will be hereafter described.
890
ORGANS OF RESPIRATION.
In form the bronchi exactly resemble the trachea on a smaller scale ;
they are rounded and firm in front and at the sides, where they are pro-
vided with imperfect cartilaginous rings, and they are flattened and mem-
branous behind.
Structure of the Trachea.
The trachea presents for consideration the elastic framework of incomplete
cartilaginous rings, layers of fibrous, muscular, and elastic substance, and the
lining mucous membrane, with glands.
The cartilages &nd fibrous membrane. — The cartilages are from sixteen to
twenty in number. Each presents a curve of rather more than two-thirds
of a circle, resembling the letter C. The depth from above downwards is
from one line and a half to two lines, and the thickness half a line. The
outer surface of each is flat, but the inner surface is convex from above
downwards, so as to give greater thickness in the middle than at the upper
and lower edge. The cartilages are held together by a strong fibrous mem-
Fig. 624.
Fig. 624. — OUTLINE SHOWING THE
GENERAL FORM OP THE LARYNX,
TRACHEA, AND BKONCHI AS SEEN
PROM BEHIND. ±
h, great cornu of the hyoid bone ; t,
superior, and t\ the inferior cornu of
the thyroid cartilage ; e, the epiglottis ;
a, points to the back of both the ary-
tenoid cartilages, which are surmounted
by the cornicula ; c, the middle ridge
on the back of the cricoid cartilage ;
tr, the posterior membranous part of
the trachea; 6, 6', right and left
bronchi.
brane. This membrane is elastic
and extensible in a certain de-
gree, and not only occupies the
intervals between the cartilages,
but is prolonged over their outer
and inner surfaces, so that
they are, as it were, imbedded
in ifc.
The layer covering the outer
side of the rings is stronger than
that within them ; and from this
circumstance, together with the
roundness of their inner surfaces,
they may be felt more pro-
minently on the interior than on
the exterior of the trachea.
The cartilages terminate ab-
ruptly behind. At the back of
the trachea, where they are
altogether wanting, the fibrous
membrane is continued across
between their ends, but it is here
looser in its texture.
STRUCTURE OF THE TRACHEA.
891
The first or highest cartilage, which is connected by the fibrous membrane
with the lower margin of the cricoid cartilage, is broader than the rest, and
is often divided at one end. Sometimes it coalesces in a greater or less
extent with the cricoid or with the succeeding cartilage. The lowest
cartilage, placed at the bifurcation of the trachea iuto the bronchi, is peculiar
in shape ; its lower border being prolonged downwards, and at the same time
bent backwards so as to form a curved projection between the two bronchi.
The cartilage next above this is slightly widened in the middle line. Some-
times the extremities of two adjacent cartilages are united together, and not
uufrequently a cartilage is divided at one end into two short branches, the
opposite end of that next it being likewise bifurcated so as to maintain the
parallelism of the entire series. The use of these cartilaginous hoops is to
keep the trachea open, a condition essential for the free passage of air into
the lungs.
Muscular fibres. — Between the fibrous and the mucous membrane at the
posterior flattened part of the trachea, there is found a continuous pale
reddish layer, consisting of unstriped muscular fibres which pass across, not
only between the posterior extremities of the cartilages, but opposite the
intervals between the rings also, and have the power of diminishing the area
of the tube by approximating the ends of the cartilages. Those which are
placed opposite the cartilages are attached to the ends of the rings, and
encroach also for a short distance upon the adjacent part of their inner
surface.
Outside the transverse fibres are some small fasciculi having a longitudinal
direction. These arise, by minute tendons of elastic tissue, in part from the
inner surface of the end of the tracheal rings, and in part from the external
fibrous membrane.
Fig. 625.
Fig. 625. — CILIATED EPITHELIUM
OP THE RESPIRATORY Mucoos
MEMBRANE.
A, vertical section of the epithe-
lial lining of the human windpipe
(from Kolliker). ^y9 a, b, sub-
jacent membrane ; c, lowest or
spheroidal cells ; d, middle or oval
cells ; e, superficial elongated and
ciliated cells.
B, separate columnar and ciliated
epithelial cells from the human
nasal membrane, ^
Mastic fibres.— Situated im-
mediately beneath the tracheal
mucous membrane, and ad-
hering intimately to it, are
numerous longitudinal fibres
of yellow elastic tissue. They
are found all round the tube,
internal to the cartilages and
the muscular layer, but are
much more abundant along the posterior membranous part, where they are
principally collected into distinct longitudinal bundles, which produce visible
elevations or flutings of the mucous membrane. These bundles are par-
B
892 ORGANS OF RESPIRATION.
ticularly strong and numerous opposite the bifurcation of the trachea. The
elastic longitudinal fibres serve to restore the windpipe to its ordinary size
after it has been stretched in the direction of its length.
The glands. — The trachea is provided with very numerous mucous gland?,
the constant secretion from which serves to lubricate its internal surface.
The largest of these glands are small roundish lenticular bodies, situated at
the back part of the tube, lying close upon the outer surface of the fibrous
layer, or occupying little recesses formed between its meshes : these are
compound glands ; their excretory ducts pass forwards between the muscular
fibres and open on the mucous membrane, where multitudes of minute
orifices are perceptible. Other similar but smaller glands are found upon
and within the fibrous membrane between the cartilaginous rings. Lastly,
there appear to be still smaller glands lying close beneath the mucous
coat.
The mucous membrane. — This is smooth and of a pale pinkish white
colour in health, though when congested or inflamed, it becomes in-
tensely purple or crimson. It is covered with a ciliated columnar epithelium,
the vibratile movements of which, as may be best seen at the back of the
trachea of an animal, tend to drive the mucous secretion upwards towards
the larynx. The epithelium is stratified, oval nucleated cells being disposed
several rows deep, beneath the columnar cells which bear the cilia.
Vessels and Nerves. — The arteries of the trachea are principally derived
from the inferior thyroid. The larger branches run for some distance longi-
tudinally, and then form a superficial plexus with rounded meshes. The
veins enter the adjacent plexuses of the thyroid veins. The nerves come
from the trunk and recurrent branches of the pneumo-gastric, and from the
sympathetic system.
Structure of the Bronchi.
The general structure of the bronchi corresponds with that of the trachea
in every particular. Their cartilaginous rings, which resemble those of the
trachea in being imperfect behind, are, however, shorter and narrower. The
number of rings in the right bronchus varies from six to eight, whilst in the
left the number is from nine to twelve.
The bronchi are supplied by the bronchial arteries and veins, and the
nerves are from the same source as those of the trachea.
THE LUNGS AND PLEURA.
The lungs, placed one on the right and the other on the left of the heart
and large vessels, occupy by far the larger part of the cavity of the chest,
and during life are always in accurate contact with the internal surface of
its wall. Each lung is attached at a comparatively small part of its inner
or median surface by a part named the root, and by a thin membranous fold
which is continued downwards from it. In other directions the lung is free
and its surface is closely covered by a serous membrane, belonging to itself
and to the corresponding side of the thorax, and named accordingly, the
right or left pleura.
THE PLEUBJE.
The pleura are two independent serous membranes forming two shut sacs,
quite distinct from each other, which line the right and left sides of the
thoracic cavity, form by their approximation in the middle line the medias-
INFLECTIONS OF THE PLEURJE.
893
tinal partition, and are reflected each upon the root and over the entire free
surface of the corresponding lung.
Each pleura consists of a visceral and a parietal portion : the visceral
portion, pleura pulmonalis, covers the lung ; and the parietal portion lines
the ribs and intercostal spaces, pleura costales, covers the upper convex
surface of the diaphragm, enters into the formation of the mediastinum, and
is reflected on the sides of the pericardium.
The mediastinum, or partition between the two pleural cavities, is formed
by the reflection of each pleura from the anterior wall of the chest back-
wards on the pericardium to the root of the lung, and from the back of the
root of the lung to the vertebral column. Its division into anterior, middle,
Fig. 626. — TRANSVERSE SECTION OP THE CHEST OF A FCETUS, ILLUSTRATING THE INFLEC-
TIONS OF THE PERICARDIUM AND PLEURJS (after Luschka and from nature).
The sketch represents the upper surface of the lower section ; the division is carried
nearly in a horizontal plane on a level with the interval in front between the fifth and
sixth ribs, s, the sternum ; c, the body of the seventh dorsal vertebra ; A, the right,
and A', the left ventricle ; ce, the cesophagus ; p n, the left pneumogastric nerve ; near
these letters respectively, the root of the right and left lungs ; the right pneumogastric
nerve is behind the cesophagus ; a, the aorta ; v a, the vena azygos ; d, thoracic duct ;
1, the cardiac pericardium ; 2, the external pericardium ; 2', the cavity of the peri-
cardium ; 3, the pulmonary pleura passing over the surface, and reflected at the roots
of the lungs ; 3', their cavity, and on the right side, the reflection at the mediastinum to
the surface of the pericardium ; 4, the external or costal pleurae ; c, c, the walls of the
chest inclosing the ribs, pectoral muscles, &c.
and posterior mediasiina, and the position and contents of each, have been
already described (p. 297).
894 THE LUXGS.
At the root of each lung which is enclosed by its own pleura, the visceral
and parietal portions of this membrane are continuous with each other ; and,
commencing immediately at the lower border of the root, there is found a
triangular fold or duplicature of the serous membrane, extending vertically
between the inner surface of the lung and the posterior mediastinum, and
reaching down to the diaphragm, to which it is attached by its extremity ;
this fold, which serves to attach the lower part of the lung, is named liya-
mentum latum pulmonis.
The upper part of each pleura, which receives the apex of the correspond-
ing lung, projects in the form of a cul-de-sac through the superior aperture
of the thorax into the neck, reaching an inch or even an inch and a half
above the margin of the first rib, and passing up under cover of the scaleui
muscles, — a small slip of which, arising from the transverse process of the
last cervical vertebra, is described by ISibson as expanding into a dome-like
aponeurosis or fascia, which covers or strengthens the pleural cul-de-sac, and
is attached to the whole of the inner edge of the first rib. The right pleura
is generally stated to reach higher in the neck than the left ; but, in twenty
observations recorded by Hutchinson, the right lung was higher in ten cases,
and the left in eight, whilst in two the height was equal on the two sides.
Anteriorly the pleural sacs of opposite sides come nearly or altogether into
contact behind the second piece of the sternum, and continue so for some
distance ; but opposite the lower end of the sternum the right pleura passes
beyond the middle line or remains close to it, while the left recedes to a
variable distance from the sternum. Inferiorly the pleurae do not pass quite
down to the attachments of the diaphragm, but leave a portion of its circum-
ference in contact with the costal parietes. Owing to the height of the
diaphragm on the right side (corresponding with the greater convexity of
the liver), the right pleural sac is shorter than the left ; it is at the same
time wider. According to Luschka the right pleura, opposite a line descend-
ing from the axilla, reaches down to the lower border of the ninth rib,
while the left pleura in the same transverse vertical plane reaches to the
lower border of the tenth rib.
Structure. — The pleura possesses the usual characters of serous membrane. The
costal part of the membrane is the thickest, and may be easily raised from the ribs
and intercostal spaces. It is strengthened in these situations by a layer of subserous
areolar tissue of considerable thickness. On the pericardium and diaphragm the
pleura is thinner and more firmly adherent; but it is thinnest and least easily
detached upon the surface of the lungs.
Luschka has described nerves in this membrane, with fine and coarse fibres, which
are traceable to the phrenic and sympathetic. Kolliker states that, in the pleura
pulmonalis of man, branches of nerves may be seen accompanying the ramifications of
the bronchial arteries.
THE LUNGS.
Form. — Each lung is shaped somewhat like a cone, having its base turned
downwards, and its inner side much flattened. The base is broad, concave,
and of a semilunar form, and rests upon the arch of the diaphragm. It is
bounded by a thin margin, which is received in the angle between the ribs
and the diaphragm ; and it reaches much lower down behind and at the
outer side than in front and towards the middle line. The apex, forms a
blunted point, and, as already mentioned, reaches into the root of the neck,
above the margin of the first rib, where it is separated from the first portion
of the subclavian artery by the pleural membrane.
FORM AND SITUATION OF THE LUNGS. 895
The outer surface of the lung, which moves upon the thoracic parietes, is
smooth, convex, and of great extent, corresponding with the arches of the
ribs and cost.tl cartilages. It is of greater depth behind than in front. The
posterior border is obtuse or rounded, and is received into the deep groove
formed by the ribs at the side of the vertebral column ; measured from above
downwards, it is the deepest part of the lung. The anterior border is thin
and overlaps the pericardium, forming a sharp margin, which touches the sides
of the anterior mediastinum, and, opposite the middle of the sternum, is
separated during inspiration from the corresponding margin of the opposite
lung only by the two thin and adherent layers of the mediastinal septum.
The inner surface is concave, and in part adapted to the convex pericardium.
Upon this surface, somewhat above the middle of the lung, and considerably
nearer to the posterior than the anterior border, is the root, where the bronchi
and great vessels join the lung. Each lung is traversed by a long and deep
fissure, which is directed from above and behind, downwards and forwards.
It commences upon the posterior border of the lung, about three inches from
the apex, and extends obliquely downwards to the anterior and inferior
angle, penetrating from the outer surface to within some inches of the root
of the organ. The upper lobe, the portion of lung which is situated above this
fissure, is smaller than the portion below, and is shaped like a cone with an
oblique base, whilst the lower and larger lobe is more or less quadrilateral.
In the right lung there is a second and shorter fissure, which runs forwards
and upwards from the principal fissure to the anterior margin, thus marking
off a third small portion, or middle lobe, which appears like an angular piece
separated from the anterior and lower part of the upper lobe. The left lung,
which has no such middle lobe, presents a deep notch in its anterior border,
into which the apex of the heart (enclosed in the pericardium) is received.
This notch is formed by the rapid retreat of the anterior margin of the upper
lobe from the middle line, opposite the lower half of the sternum ; while in-
ferior ly a tongue-like process of the lower lobe usually projects slightly inwards
towards the middle line. Besides these differences in form which distinguish
the lungs, it is to be noted that the right lung is shorter, but at the same
time wider, than the left, the perpendicular measurement of the former being
less, owing to the diaphragm rising higher on the right side to accommodate
the liver, whilst the breadth of the left lung is narrowed, owing to the heart
and pericardium encroaching on the left half of the thorax. On the whole,
however, as is seen on a comparison of their weights, the right is the larger
of the two lungs.
At the apices and posterior borders the extent of the lungs accurately cor-
responds with that of the pleural sacs which contain them, but at the anterior
and inferior margins it is not so : the anterior margins pass forwards most
completely between the mediastinal and costal pleura during inspiration, and
retire to a variable degree from between them in expiration ; and in like
manner the inferior margins descend, during inspiration, between the costal
and diaphragmatic pleurae, while probably at no time do they ever descend
completely to the line of reflection between those membranes.
Weight, Dimensions, and Capacity. — The lungs vary much in size and
weight according to the quantity of blood, mucus, or serous fluid they may
happen to contain, which is greatly influenced by the circumstances im-
mediately preceding death, as well as by other causes. The weight of both
lungs together, as generally stated, ranges from thirty to forty-eight ounces,
the more prevalent weights being found between thirty-six and forty-two
ounces. The proportion borne by the right lung to the left is nearly that of
896 THE LUNGS.
twecty-two ounces to twenty, taking the combined weight of the two at
forty-two ounces. The lungs are not only absolutely heavier in the male
than in the female, but appear to be heavier in proportion to the weight of
the body. The general ratio between the weight of the lungs and body, in
the adult, fluctuates according to the estimate of Krause, between one to
thirty-five and one to fifty.
The following tables, deduced from Reid's and Hutchinson's observations, show the
average weight of the right and left lungs, and of both lungs together, and also the
relative weight of the lungs to the body in a certain number of adults of both sexes.
AVERAGE WEIGHT IN TWENTY-NINE MALES AND TWENTY-ONE FEMALES.— (REID.)
MALE. FEMALE.
Eight lung 24 oz 17 oz.
Left lung 21 oz 15 oz.
45 oz. 32 oz.
AVERAGE IN TWENTY-FIVE MALES AND THIRTEEN FEMALES. — (REID AND HUTCHINSON.)
MALE. FEMALE.
Proportionate weight of the lungs to the body ... 1 to 37 1 to 43
The size and cubical dimensions of the lungs are influenced so much by their state
of inflation, and are therefore so variable, that no useful application can be made of
many of the statements given as to these measurements. It is important, however,
to ascertain the quantity of air which they contain under different conditions. This
subject has been investigated by many inquirers, whose statements on this point,
however, are exceedingly various. The volume of air contained in the lungs after
a forced expiration, has been estimated by Goodwyn at 109 cubic inches. After
an ordinary expiration it would seem that at least 60 cubic inches more are retained
in the chest, giving a total of 170 cubic inches in that condition of the lungs. The
amount of air inhaled and expelled in ordinary breathing has been very differently
estimated by different observers; it is most probably from 16 to 20 cubic inches.
According to the extensive researches of Hutchinson, men of mean height, between
five and six feet, after a complete inspiration, expel from the chest, by a forced expira-
tion, on an average, 225 cubic inches of air, at a temperature of 60°. This quantity
is called by Hutchinson the vital capacity of the lungs. If to it be added the average
quantity found by Goodwyn to be retained in the lungs after complete expiration, viz.
109 cubic inches,' the result will yield 334 cubic inches of air at 60°, as the average
total capacity of the respiratory organs for air in an adult male of ordinary height.
The vital capacity (or difference between extreme expiration and extreme inspira-
tion) is found by Hutchinson to bear a very uniform relation to the height of the
individual, increasing at the rate of eight cubic inches for every additional inch of
stature above five feet. Its relations with the weight of the body are not thus regu-
larly progressive, for it appears to increase about one cubic inch for each additional
pound between the weights of 105 Ib. and 155 lb., or 7^ stones and 11 stones, and to
decrease at a similar rate between the weights of 11 and 14 stones, or 155 and 200 Ibs.
From the age of 15 to 35 years the vital capacity continues to advance with the growth
and activity of the frame, but between the ages of 35 and 65 it diminishes at the rate
of upwards of 1 cubic inch per annum. This differential or vital capacity is by no
means in proportion to the size of the thorax, whether that be estimated by the cir-
cumference of the chest, or by the sectional area of its base, or by its absolute capacity,
as ascertained by measuring its cubical contents after death. It is found rather, that
the vital capacity is strictly commensurate with the extent of the thoracic movements,
and with the integrity of the lungs themselves ; so that in phthisis, for example, it
becomes reduced by a quantity vary ing from 10 to 70 per cent., according to the stage
of the disease. A change from the erect to the sitting posture is accompanied by a
diminution of the vital capacity, which in one case fell from 260 to 255 cubic inches,
and on lying down, it was farther diminished to 230 cubic inches in the supine, and
220 cubic inches in the prone position of the body. Lastly, it is lowered by from 12
GENERAL STRUCTURE OF THE LUNGS. 897
to 20 cubic inches by the presence of a full meal in the stomach. (Hutchinson, in
Journal of Statistical "Society, August, 1844; and in Medico-Chirurg. Transactions,
vol. xxix., 1846 ; also, in the article " Thorax," in Cyclopaedia of Anatomy and Phy-
siology, and the article " Respiration," by Reid, in the same.)
Texture and consistence. — The substance of the lung is of a light porous
spongy structure, and, when healthy, is buoyant in water : but in the foetus,
before respiration has taken place, and also in certain cases of congestion, col-
lapse, or consolidation from disease, the entire lungs, or portions of them,
sink in that fluid. The specific gravity of a healtliy lung, as found after
death, varies from 345 to 746, water being 1000. When the lung is fully
distended its specific gravity is 126, whilst that of the pulmonary substance,
entirely deprived of air, is 1056. (Krause.) When pressed between the fingers,
the luugs impart a crepitant sensation, which is accompanied by a peculiar
noise, both effects being caused by the air contained in the tissue. On cutting
into the lung, the same crepitation is heard, and there exudes from the cut
surface a reddish frothy fluid, which is partly mucus from the air-tubes and
air-cells, and partly a serous exudation, tinged with blood, and rendered
frothy by the admixed air. This fluid escapes in largest quantity from the
posterior portion of the lung.
The pulmonary tissue is endowed with great elasticity, in consequence of
which the lungs collapse to about one-third of their bulk when the thorax is
opened, and the resistance offered by the walls of that cavity to the atmos-
pheric pressure on their outer surface is in this way removed. Owing to this
elasticity also, the lungs, if artificially inflated out of the body, contract to
their previous volume when the air is again allowed to escape.
Colour. — In infancy the lungs are of a pale rose- pink colour, which might
be compared to blood-froth ; but as life advances ,they become darker, and
are mottled or variegated with spots, patches, and streaks of dark slate-colour,
which sometimes increase to such a degree as to render the surface almost
uniformly black.
The dark colouring matter found in these streaks is in the form of granules and
collections of granules, not inclosed in cells ; it is deposited in the interstitial areolar
tissue mostly near the surface of the lung, and is not found so abundantly in the
deeper substance. It exists sometimes in the air-cells, and on the coats of the larger
vessels. Its quantity increases with age, and is said to be less abundant in females
than in males. In persons who follow the occupation of quarriers, more especially
colliers, the lungs are often intensely charged with black matter. The black colouring
substance of the lung seems to be composed of a mixture of carbon and some animal
matter. A black substance of precisely the same nature is found in the bronchial
glands. In exceptional cases the adult lungs are found with only very slight streaks
of pigment.
Root of the Lung.
The root of each lung is composed of the bronchus and the large blood-
vessels, together with the nerves, lymphatic vessels, and glands, connected
together by areolar tissue, and enclosed in a sheath of the pleura.
The root of the right lung lies behind the superior vena car a and part of
the right auricle, and below the azygos vein, which arches over it to enter
the superior cava. That of the left lung passes below the arch of the aorta,
and in front of the descending aorta. The phrenic nerve descends in front
of the root of each lung, and the pneumogastric nerve behind, whilst the
ligamentum latum pulmonis is continued from the lower border. The
bronchus, together with the bronchial arteries and veins, the lymphatics
3 N
898
and lymphatic glands, are placed on a plane posterior to the great blood-
vessels ; the pulmonary artery lies more forward than the bronchus, and to
a great extent conceals it, whilst the pulmonary veins are placed still farther
in advance. The pulmonary plexuses of nerves lie on the anterior and
posterior aspect of the root beneath the pleura, the posterior being the
larger of the two.
The order of position of the great air-tube and pulmonary vessels from
above downwards differs on the two sides ; for whilst on the right side the
bronchus is highest and the pulmonary artery next, on the left, the air-
tube, in passing obliquely beneath the arch of the aorta, is depressed below
the level of the left pulmonary artery, which is the highest vessel. On both
sides the pulmonary veins are the lowest of the three sets of tubes.
Before entering the substance of the lung, the bronchus divides into two
branches, an upper and a lower, one for each lobe. The lower branch is the
larger of the two, and on the right side gives off a third small branch which
enters the middle lobe of that lung.
The pulmonary artery also divides, before penetrating the lung to which
it belongs, into two branches, of which the lower is the larger and supplies
the inferior lobe. The upper of these two branches gives the branch to the
middle lobe. A similar arrangement prevails in regard to the right pulmo-
nary veins, the upper one of which is formed by branches proceeding from
the superior and middle lobes of the right lung.
STRUCTURE OF THE LUNGS.
Coverings. — Beneath the serous covering, already noticed, there is placed
a thin layer of subserous areolar membrane mixed with much elastic tissue.
It is continuous with the areolar tissue in the interior of the lung, and has
been described as a distinct coat under the name of the second or deeper
layer of the pleura. In the lungs of many animals, such as the lion, seal,
and leopard, this subserous layer forms a very strong membrane, composed
principally of elastic tissue.
Lobules. — The substance of the lung is composed of numerous small
lobules which are attached to the ramifications of the air-tubes, and are held
together by those tubes, by the blood-vessels, and by an interlobular areolar
tissue. These lobules are of various sizes, the smaller uniting into larger
ones ; they are bounded by flattened sides, and compactly fitted to each
other and to the larger air-tubes and vessels of the lungs, those on the
surface of the organ having bases, turned outwards, from half a line to a
line in diameter. Though mutually adherent by means of fine areolar
tissue, they are quite distinct one from the other, and may be readily sepa-
rated by disgection in the lungs of young animals, and in those of the
human foetus. They may be regarded as lungs in miniature, the same
elements entering into their composition as form the lung itself. The struc-
ture of a single lobule represents in fact that which is essential in the entire
organ, each lobule, besides its investment of areolar membrane, being made
up of the following constituents : the air-tubes and their terminating cells,
the pulmonary and bronchial blood-vessels, with lymphatics, nerves, and
interstitial areolar tissue.
Air-tubes. — The principal divisions of the bronchi, as they pass into the
lungs, divide into tubes of less calibre, and these again subdivide in suc-
cession into smaller and smaller bronchial tubes, or bronchia, which, diverg-
ing in all directions, never anastomose, but terminate separately in the
STRUCTURE OF THE AIR-TUBES.
899
pulmonary parenchyma. The prevailing form of division is dichotomous ;
but sometimes three branches arise together, and often lateral branches are
given off at intervals from the sides of a main trunk. The larger branches
diverge at rather acute angles, but the more remote and smaller ramifications
spring less and less acutely. After a certain stage of subdivision each bron-
chial tube is reduced to a very small size, and, forming what has been
termed a lobular bronchial tube, enters a distinct pulmonary lobule, within
which it undergoes still farther division, and at last ends in the small
cellular recesses named air-cells or pulmonary cells.
Within the lungs the air-tubes are not flattened behind like the bronchi
and trachea, but form completely cylindrical tubes. Hence, although they
contain the same elements as the larger air-passages, reduced gradually to a
state of greater ar.d greater tenuity, they possess certain peculiarities of
structure. Thus, the cartilages no longer appear as imperfect rings running
only upon the front and lateral surfaces of the air-tube, but are scattered
over all sides of the tube in the form of irregularly shaped plates of various
sizes. These are most developed at the points of division of the bronchia,
where they form a sharp, concave ridge projecting inwards into the tube.
They may be traced, becoming rarer and rarer and more reduced in size, as
far as bronchia only one-fourth of a line in diameter, beyond which the tubes
are entirely membranous. The Jibrous coat extends to the very smallest
tubes, becoming thinner by degrees and degenerating into areolar tissue.
The mucous membrane, which extends throughout the whole system of air
passages, and is continuous with that lining the air-cells, is also thinner
than in the trachea and bronchus, but it retains its ciliated columnar
epithelium. The yellow longitudinal bundles of elastic fibres are very dis-
tinct in both the large and small bronchia, and may be followed by dissection
as far as the tube can be laid open, and by the microscope into the smallest
Fig. 627.
Fig. 627.— PORTION OP THE
OUTER SURFACE OF inn
Cow's LUNG (from Kol-
liker after Hurting. ~
a, pulmonary vesicles filled
artificially with wax ; 6, the
margins of the smallest lobules
or infuudibula.
tubes. The muscular
fibres, which in the trachea
and bronchi are confined
to the back part of the
tube, surround the bron-
chial tubes with a con-
tinuous layer of annular
fibres, lying inside the
irregular cartilaginous
plates ; they are found, however, beyond the place where the cartilages
cease to exist, and appear as irregular annular fasciculi even in the smallest
tubes.
Air-cells or Pulmonary vesicles. — These cells, in which the finest ramifi-
cations of each lobular bronchial tube ultimately terminate, are in the
natural state always filled with air. They are readily seen on the surface
and in a section of a lung which has been inflated with air and dried ;
3 N 2
900
THE LUNGS.
also upon portions of foetal or adult lung injected with mercury. In the
lungs of some animals, as of the lion, cat, and dog, they are very large,
and are distinctly visible on the surface of the organ. In the adult human
lung their most common diameter is about -y^^th of an inch, but it varies
from j^Qth to TVta of an inch ; they are larger on the surface than in the
interior, and largest towards the thin edges of the organ : they are also
said to be very large at the apex of the lung. Their dimensions go on
increasing from birth to old age, and they are larger in men than in women.
In the infant their diameter is usually under -^^th of an inch.
The small bronchial tube entering each lobule divides and subdivides
from four to nine times, according to the size of the lobule ; its branches,
which diverge at less and less acute angles, at first diminish at each subdi-
vision, but afterwards continue stationary in size, being from ^th to ^ota
of an inch in diameter. They lose at last their cylindrical form, and are
converted into irregular lobular passages, beset, at first sparingly, but after-
wards closely and on all sides, with numerous little recesses or dilatations,
and ultimately terminate near the surface of the lobule in a group of similar
recesses. These small recesses, whether seated along the course or at the
Fig. 628. Fig. 628. — SEMIDIAGRAMMATIC REPRESENTA-
TION OP Two SMALL LOBULI FROM NEAR THE
SURFACE OF THE LUNG OF A NEW-BORN CHILD
(from Kolliker). 2f
a, exterior of the two lobuli or infundibula ;
6, pulmonary vesicles or alveoli on these and on
c, the smallest bronchial ramifications.
extremity of an air passage, are the air-
cells or alveoli ; and each group of alveoli
with the comparatively large passage
between them constitutes an infundi-
bulum, so called from the manner in
which it dilates from the extremity of
the bronchial tube. The arrangement of
these finest air -passages and air-cells
closely resembles, though on a smaller
scale, the reticulated structure of the
tortoise's lung, in which large open
passages lead in all directions to clusters of wide alveoli, separated from
each other by intervening septa of various depths.
At the point where the small bronchial tubes lose their cylindrical
character, and become covered on all sides with the cells, their structural
elements also undergo a change. The muscular layer disappears, the longi-
tudinal elastic bundles are broken up into an interlacement of areolar and
elastic tissue, which surrounds the tubes and forms the basis of their walls.
The mucous membrane becomes exceedingly delicate, consisting merely of a
thin transparent membrane, covered by a stratum of squamous instead of
ciliated cylindrical epithelium.
The walls of the alveoli, their orifices, and the margins of the septa, are
supported and strengthened by scattered and coiled elastic fibres, in addition
to which, according to Moleschott, Gerlach, and Hirschmann, there is like-
wise an intermixture of muscular fibres. It was stated by Rainey, and
corroborated by Todd and Bowman, and it is still maintained by Henle,
Luschka, and others, that the alveoli are destitute of all epithelium. The
MINUTE STRUCTURE OF THE AIR-CELLS.
901
presence of nuclei, however, situated in the capillary meshes, and of larger
size than those which belong to the capillary walls, is allowed on all hands ;
and the majority of recent observers declare the existence of exceedingly
Fig. 629.
f
Fig. 629. — DIAGRAMS ILLUSTRATING THE PROGRESSIVE ADVANCE IN THE CELLULAR
STRUCTURE OF THE LUNGS OP KEPTILES.
A, the upper portion of the lung of a serpent : the summit has cellular walls, the
lower part forms merely a membranous sac. B, lung of the frog, in which the cellular
structure extends over the whole internal surface of the lung, but is more marked at the
upper part. C, lung of the turtle : the cells here have extended so as to occupy nearly
the whole thickness of the lung.
delicate squamoua epithelial cells. These, according to Eberth, lie in the
capillary meshes, from one to three in each, but leave the surfaces of the
capillary vessels uncovered. According to others, they join each other over
the capillary blood-vessels.
Fig. 630.
Fig. 630. — FRAGMENT OF THE INJECTED LUNG OF A YOUNG PIG, SHOWING THE MINUTE
STRUCTURE OF THE VESICLES (from Hirschmann and Chrzonszczewsky).
a, the areolar and elastic tissue supporting the vesicles ; 6, the cavities of two of the
vesicles partially cut through ; c, the ineshes of the pulmonary capillaries, the latter
being filled with dark colouring matter, and the meshes being occupied by regular
hexagonal epithelial cells, which in various places are seen to meet each other over the
capillary vessels ; d, the intervesicular pulmonary vessels. In this instance, the cells
observed in each mesh have been more numerous than they are said by Eberth to be in
the human subject.
902
THE LUNGS.
The following writers, among others, maintain the existence of epithelium in the
air-cells: Addison, in Phil. Trans., 1842; Eossignol, Recherches sur la Structure
intime du Poumon, 1846; Waters, Anatomy of the Human Lung, 1860; Kolliker, in
his Gewebelehre; Eberth, in Virchow's Archiv. xxiv., p. 503 ; and Julius Arnold, in
Yirchow's Archiv. xxviii., p. 433 ; Hirschmann, in the same, xxxvi. with addition and
drawings by Chrzonszczewsky. The following are among those who deny the existence
of epithelium : — Rainey, in Med.-Chir. Trans., vol. xxviii , 1845; and in Brit, and For.
Med.-Chir. Eeview, 1855; Radclyffe Hall, in Med.-Chir. Review, July, 1857; Luschka
and Henle, in their works on Human Anatomy; Badoky, in Virchow's Archiv., xxxiii.
p. 264.
Fig. 631.
Fig. 631. — CAPILLARY NET-
WORK OP THE PULMONARY
BLOOD-VESSELS IN THE HU-
MAN LUNU (from Kolli-
ker). ^
The capillary network
of the pulmonary vessels
is spread beneath the thm
transparent mucous mem-
brane of both the ter-
minal and lateral air-cells,
and is found wherever the
finest air-tubes have lost
their cylindrical character,
and become beset with
cells. Around the ex-
terior of each cell there
is an arterial circle, which
communicates freely with
similar neighbouring circles, the capillary systems of ten or twelve cells being
thus connected together, as may be seen upon the surface of the lung. From
Fig. 632. Fig. 632.— CAPILLARY NETWORK ON THE PUL-
MONARY VESICLES OF THE HORSE (from Frey
after a preparation by Gerlach). '-f-0
a, the capillary network ; 6, the terminal
branches of the pulmonary artery passing
towards and surrounding in part each pul-
monary vesicle.
these circular vessels, which vary in dia-
meter from i-^jifiToi to ^jgth of an inch,
the capillary network arises, covering the
bottom of each cell, ascending also between
the duplicature of mucous membrane in
the intercellular septa, and surrounding
the openings of the cells. As was pointed
out by Rainey, the capillary network,
where it rises into the intercellular parti-
tions, although it forms a double layer in the lungs of reptiles, is single in
the lungs of man and mammalia.
The capillaries are very fine, the smallest measuring, in injected specimens,
from -*11 to **1 of an ilicb ; tlie network is so close that the meshes
PULMONARY AND BRONCHIAL CAPILLARIES. 903
are scarcely wider than the vessels themselves. Those which lie nearest to
the mouths of the alveoli are observed arching and coiled over and through
the elastic fibres found in the interalveolar septa (Luschka and Badoky).
The coats of the capillaries are also exceedingly thin, and thus more readily
allow the free exhalation and absorption of which the pulcnouary cells are
the seat.
The branches of the pulmonary artery accompany the bronchial tubes, but they sub-
divide more frequently, and are much smaller, especially in their remote ramifications.
They ramify without anastomoses, and at length terminate upon the walls of the
air-cells and on those of the bronchia in a fine and dense capillary network, from
which the radicles of the pulmonary veins arise. The smaller branches of these veins,
especially near the surface of the lung, frequently do not accompany the bronchia and
arterial branches (Addison, Bourgery), but are found to run alone for a short distance
through the substance of the organ, and then to join some deeper vein which passes
by the side of a bronchial tube, uniting together, and also forming, according to Ros-
signol, frequent lateral communications. The veins coalesce into large branches,
which at length accompany the arteries, and thus proceed to the root of the lung. In
their course through the lung, the artery is usually found above and in front of a
bronchial tube, and the vein below.
The pulmonary vessels differ from the systemic in regard to their contents, inas-
much as the artery conveys dark blood, whilst the veins carry red blood. The pul-
monary veins, unlike the other veins of the body, are not more capacious than their
corresponding arteries ; indeed, according to Winslow, Santorini, Haller, and others,
they are somewhat less so. These veins have no valves. Lastly, it may be remarked
that, whilst the arteries of different lobules are independent, their veins freely anas-
tomose together.
The bronchial vessels. — The bronchial arteries and veins, which are much
smaller than the pulmonary vessels, carry blood for the nutrition of the
lung, and are doubtless also the principal source of the mucous secretion
found in the interior of the air tubes, and of the thin albuminous fluid
which moistens the pleura pulmonalis.
The bronchial arteries, from one to three in number for each lung, arise
from the aorta, or from an intercostal artery, and follow the divisions of the
air-tubes through the lung. They are ultimately distributed in three ways :
(1) many of their branches ramify in the bronchial lymphatic glands, the
coats of the large blood-vessels, and in the fibrous and muscular walls of
the large and small air-tubes, and give supply to a copious capillary plexus
iu the bronchial mucous membrane, which in fine bronchial tubes is con-
tinuous with that supplied by the pulmonary artery ; (2) others form plexuses
in the interlobular areolar tissue ; (3) branches spread out upon the surface
of the lung beneath the pleura, forming plexuses and a capillary network,
which may be distinguished from those of the pulmonary vessels of the
superficial air-cells by their tortuous course and open arrangement, and also
by their being outside the investing membrane of tho lobules, and by ulti-
mately ending iu the branches of the superficial sat of bronchial veins.
The bronchial veins have not quite so large a distribution in the lung as
the bronchial arteries, since part of the blood carried by the bronchial
arteries is returned by the pulmonary veins. The superficial and deep
bronchial veins unite at the root of the lung, opening on the right side into
the vena azygos, and on the left usually into the superior intercostal vein.
The absorbent vessels of the lungs have been already sufficiently described
(p. 496).
Nerves. — The lungs are supplied with nerves from the anterior and posterior
pulmonary plexuses (pp. 023, 093). These are formed chiefly by branches
904 ^ THE LUNGS.
from the pneumogastric nerves, joined by others from the sympathetic
system. The fine nervous cords enter at the root of the lung, and follow
the air-tubes. Their final distribution requires further examination. Accord-
lug to Remak, whitish filaments from the par vagum follow the bronchia as
far nearly as the surface of the lung, and greyish filaments, proceeding from
the sympathetic, and having very minute ganglia upon them in their course,
pass both to the bronchia and pleura. Julius Arnold has discovered
remarkable bell-shaped gangliouic corpuscles terminating the pulmonary
nerves of the frog. (Virchow's Archiv., vol. xxviii. p. 453.)
DEVELOPMENT OF THE LUNGS AND TRACHEA.
The lungs first appear as two small protrusions upon the front of the cesophageal
portion of the alimentary canal, completely hid by the rudimentary heart and liver.
These primitive protrusions or tubercles are visible in the chick on the third day of
incubation, and in the embryos of mammalia and of man at a corresponding stage of
advancement. Their internal cavities communicate with the oesophagus, and are lined
by a prolongation of its inner layer. At a later period they are connected with the
oesophagus by means of a long pedicle, which ultimately forms the trachea, whilst the
bronchia and air-cells are developed by the progressive ramification of the internal
cavity in the form of caecal tubes, after the manner of the ducts of glands. Ac-
cording to Kolliker, the human lung in the latter half of the second month presents
a granular appearance on the surface, produced by the primitive air-cells placed at the
extremities of ramified tubes, which occupy the whole of the interior of the organ ;
the ramification of the bronchial twigs and multiplication of air-cells goes on in-
creasing, and this to such an extent that the air-cells in the fifth month are only half
the size of those which are found in the fourth month.
Fig. 633. Fig. 633. — SKETCH ILLUSTRATING THE DEVE-
LOPMENT OP THE RESPIRATORY ORGANS
A B c (from Rathke).
A, oesophagus of a chick, on the fourth
day of incubation, with the rudimentary
lung of the left side, seen laterally ; 1, the
front, and 2, the back of the oesophagus ;
3, rudimentary lung protruding from that
tube ; 4, stomach. B, the same seen in
front, so as to show both lungs. C, tongue
and respiratory organs of embryo of the
horse ; 1, tongue ; 2, larynx ; 3, trachea ;
4, lungs seen from behind.
For a long time the lungs are very small, and occupy only a limited space at the back
part of the chest. In an embryo, 16 lines in length, their proportionate weight to the
body was found by Meckel to be 1 to 25 ; in another, 29 lines long, it was 1 to 27 ;
in another, 4 inches in length, 1 to 41 ; and at the full period, 1 to 70. Huschke
found that the lungs of still-born male children were heavier in proportion to the
weight of the body than those of female children ; the ratio being, amongst females,
1 to 76, and in males, 1 to 55.
CHANGES AFTER BIRTH. — The lungs undergo very rapid and remarkable changes
after birth, in consequence of the commencement of respiration : these affect their
size, position, form, consistence, texture, colour, and weight, and should be carefully
studied, as furnishing the only means of distinguishing between a still-born child and
one that has respired.
1. Position, aize, and form.— In a foetus at the full period, or in a still-born child, the
lungs, comparatively small, lie packed at the back of the thorax, and do not entirely
cover the sides of the pericardium ; subsequently to respiration, they expand, and com-
pletely cover the pleural portions of that sac, and are also in contact with almost the
THE LARYXX.— ITS CARTILAGES. 905
whole extent of the thoracic wall, where it is covered with the pleural membrane.
At the same time, their previously thin sharp margins become more obtuse, and their
whole form is less compressed.
2. Consistence, texture, and colour. — The introduction of air and of an increased
quantity of blood into the foetal lungs, which ensues immediately upon birth, con-
verts their tissue from a compact, heavy, granular, yellowish-pink, gland-like substance,
into a loose, light, rose-pink, spongy structure, which, as already mentioned, floats in
water. The changes thus simultaneously produced in their consistence, colour, and
texture, occur first at their anterior borders, and proceed backwards through the lungs :
they, moreover, appear in the right lung a little sooner than in the left.
3. Weight. — The absolute weight of the lungs, having gradually increased from the
earliest period of development to birth, undergoes at that time, from the quantity of
blood then poured into them, a very marked addition, amounting to more than one-
third of their previous weight : for example, the lungs before birth weigh about one and
a half ounce, but, after complete expansion by respiration, they weigh as much as two
and a half ounces. The relative weight of the lungs to the body, which at the termi-
nation of intra-uterine life is about 1 to 70, becomes, after respiration, on an average,
about 1 to 35 or 40 ; a proportion which is not materially altered through life.
Their specific gravity is at the same time changed from 1'056 to about '342.
4. Changes in the trachea after birth. — In the foetus the trachea is flattened before
and behind, its anterior surface being even somewhat depressed ; the ends of the car-
tilages touch ; and the sides of the tube, which now contains only mucus, are applied
to one another. The effect of respiration is at first to render the trachea open, but
it still remains somewhat flattened in front, and only later becomes convex.
THE LARYNX, OR ORGAN OF VOICE.
The upper part of the air-passage is modified in its structure to form the
organ of voice. This organ, named the larynx, is placed at the upper and
fore part of the neck, where it forms a considerable prominence in the
middle line. It lies between the large vessels of the neck, and below the
tongue and os hyoides, to which bone it is suspended. It is covered in
front by the cervical fascia along the middle line, and on each side by the
steruo-hyoid, sterno- thyroid, and thyro-hyoid muscles, by the upper end of
the thyroid body, and by a small part of the inferior constrictor of the
pharynx. Behind, it is covered by the pharyngeal mucous membrane, and
above it opens into the cavity of the pharynx.
The larynx consists of a framework of cartilages, articulated together
and connected by proper ligaments, two of which, named the true vocal
cords, are more immediately concerned in the production of the voice. It
also possesses muscles, which move the cartilages one upon another, and
modify the form and tension of its apertures, a mucous membrane lining its
internal surface, numerous mucous glands, and lastly, blood-vessels,
lymphatics, and nerves, besides areolar tissue and fat.
Cartilages of the Larynx.
The cartilages of the larynx consist of three single and symmetrical
pieces, named respectively the thyroid cartilage, the cricoid cartilage, and
the cartilage of the epiglottis, and of six others, which occur in pairs,
namely, the two arytenoid cartilages, the cornicula laryngis, and the cunei-
form cartilages. In all there are nine distinct pieces, the two coruicula and
two cuneiform cartilages being very small. Of these, only the thyroid and
cricoid cartilages are seen on the front and sides of the larynx ; the aryte-
noid cartilages, surmounted by the cornicula laryngis, together with the
back of the cricoid cartilage, on which they rest, form the posterior wall of
906
THE LABYNX.
the larynx, whilst the epiglottis is situated in front, and the cuneiform
cartilages on each side of the upper opening.
The thyroid cartilage is the largest of the pieces composing the frame-
work of the larynx. It is formed by two flat lamellae, united in front at an
acute angle along the middle line, where they form a projection at the upper
part. This angular projection is subcutaneous, and is much more prominent
in the male than iii the female, being named in the former the pomum
Adami. The two symmetrical halves or lamellae, named the alee, are some-
what quadrilateral in form : the anterior border where they are joined is the
shortest, the pomum Adami being surmounted by a deep notch ; the
posterior free border of each, thickened and vertical, is prolonged upwards
and downwards into two processes or cornua, and gives attachment to the
stylo-pharyngeus and palato-pharyrigeus muscles ; the superior and inferior
borders are both of them concave immediately in front of the cornua, while
the superior is convex in its anterior half, and the inferior is nearly straight.
The external flattened surface of each ala is marked by an indistinct oblique
line or ridge, which, commencing at a tubercle situated at the back part of
the upper border of the cartilage, passes downwards and forwards, so as to
mark off the anterior three fourths of the surface from the remaining pos-
terior portion. This line gives attachment below to the sterno- thyroid , and
above to the thyro-hyoid muscle, whilst the small smooth surface behind it
gives origin to part of the inferior constrictor of the pharynx, and affords
attachment, by means of areolar tissue, to the thyroid body. On their
internal surfaces, the two alee are smooth and slightly concave, and by their
Fig. 634.
Fig. 634. — CARTILAGES OF THE LARYNX SEEN FROM
BEFORE. I
1 to 4, thyroid cartilage ; 1, vertical ridge or
pomum Adami ; 2, right ala ; 3, superior, and 4,
infei ior cornu of the right side ; 5, 6, cricoid carti-
lage ; 5, inside of the posterior part ; 6, anterior
narrow part of the ring ; 7, arytenoid cartilages.
union in front, form a narrow angle within.
Of the four cornua, all of which bend in-
wards, the two superior or great cornua, pass
backwards, upwards, and inwards, and ter-
minate each by a blunt extremity, which is
connected, by means of the lateral thyro-
hyoid ligament, to the tip of the corresponding
great cornu of the os hyoides. The inferior or
smaller cornua, which are somewhat thicker
but shorter, are directed forwards and inwards,
and present each, on the inner aspect of the
tip, a smooth surface, for articulation with a
prominence on the side of the cricoid carti-
The cricoid cartilage, so named from being shaped like a ring, is thicker
in substance and stronger than the thyroid cartilage. It 13 deep behind,
where the thyroid cartilage is deficient, measuring in the male about an
inch from above downwards ; but in front its vertical measurement is dimi-
nished to a fourth or a fifth of an inch. This diminution is caused by the
direction of the superior border, which rises in a convex elevation behind, and
ARYTEXOID CARTILAGES.
907
descends with a deep concavity in front below the thyroid cartilage ; "while
the inferior border is horizontal, and connected by membrane to the first
ring of the trachea. The posterior elevated part of the upper border is
slightly notched in the middle line ; and on the sides of this notch are two
convex oval articular facets, directed upwards and outwards, with which the
arytenoid cartilages are articulated. The external surface of the cartilage
is convex and smooth in front and at the sides, where it affords attachment
to the crico-thyroid muscles, and behind these to the inferior constrictor
muscle on each side : posteriorly it presents in the middle line a slight ver-
tical ridge, to which some of the longitudinal fibres of the oesophagus are
attached. On each side of this ridge is a broad depression occupied by the
posterior crico-arytenoid muscle, and externally and anteriorly to that a small
rounded and slightly raised surface for articulation on either side with the
inferior cornu of the thyroid cartilage. The internal surface is in contact
throughout with the mucous membrane of the larynx. The lower border
of the cricoid cartilage i* circular, but higher up it is somewhat compressed
laterally, so that the passage through it is elliptical
The arytenoid cartilages are two in number, and are of a symmetrical
form. They may be compared to three-sided pyramids recurved at the
summit, resting by their bases on the posterior and highest part of the
cricoid cartilage, and approaching near to one another. Each measures
from five to six lines in height, about three lines in width, and, in
the middle of its inner surface, more than a line from before backwards.
Of the three faces, the posterior is broad, triangular, and excavated from
above downwards, lodging part of the arytenoid muscle. The anterior
Fig. 635.
Fig. 635. — OUTLINE SHOWING THE
POSITION AND FOBM OF THE ARY-
TENOID CARTILAGES FROM BEHIND, f
A, hyoid bone ; t, the superior, and
t!t the inferior cornu of the thyroid
cartilage ; c, placed on the median
ridge of the back of the cricoid carti-
lage ; a, placed between the two ary-
tenoid cartilages, to which the letter
points by two dotted lines ; the carti-
lages of Santorini or cornicula are
shown above the upper angles ; tr, the
trachea.
surface, convex in its general
outline, and somewhat rough,
gives attachment to the thyro-
arytenoid muscle, and, by a small
tubercle, to the corresponding
superior or false vocal cord. The
internal surface, which is the
narrowest of the three, and
slightly convex, is nearly parallel
with that of the opposite cartilage,
being covered by the laryngeal
mucous membrane. The anterior and posterior borders, which limit the
internal face, ascend nearly in the same vertical plane, whilst the external
border, which separates the anterior from the posterior surface, is directed
obliquely upwards and inwards.
908 THE LARYNX.
The base of each arytenoid cartilage is slightly hollowed, having towards
its inner part a smooth surface for articulation with the cricoid cartilage.
Two of its angles are remarkably prominent, viz., one external, short, and
rounded, which projects backwards and outwards, and into which the pos-
terior and the lateral crico-arytenoid muscles are inserted ; the other ante-
rior, which is more pointed, and forms a horizontal projection forwards, to
which the corresponding true vocal cord is attached.
The apex of each arytenoid cartilage curves backwards and a little in-
wards, and terminates in a blunt point, which is surmounted by a small
cartilaginous appendage named corniculum laryngis.
The cornicula laryngis, or cartilages of Santorini, are two small yellowish
cartilaginous nodules of a somewhat conical shape, which are articulated
with the summits of the arytenoid cartilages, and serve as it were to pro-
long them backwards and inwards. They are sometimes continuous with
the arytenoid cartilages.
The cuneiform cartilages, or cartilages of Wrisberg, are two very small,
soft, yellowish cartilaginous bodies, placed one on each side of the larynx
in the fold of mucous membrane, which extends from the summit of the
arytenoid cartilage to the epiglottis. They have a conical form, their base
or broader part being directed upwards. They occasion small conical eleva-
tions of the mucous membrane in the margin of the superior aperture of the
larynx, a little in advance of the cartilages of Santorini, with which, how-
ever, they are not directly connected.
The epiglottis is a median lamella of yellow cartilage, shaped somewhat
like an ovate or obcordate leaf, and covered by mucous membrane. It is
placed in front of the superior opening of the larynx, projecting, in the
ordinary condition, upwards immediately behind the base of the tongue ; but
during the act of swallowing it is carried downwards and backwards over
the entrance into the larynx, which it covers and protects.
The cartilage of the epiglottis is broad and somewhat rounded at its upper
free margin, but inferiorly it becomes pointed, and is prolonged by means of
a long, narrow, fibrous band (the thyro-epiglottic ligament) to the deep
angular depression between the alee of the thyroid cartilage, to which it is
attached, behind and below the median notch. Its lateral borders, which
are convex and turned backwards, are only partly free, being in part con-
cealed within the folds of mucous membrane, which pass back on each side
to the arytenoid cartilages. The anterior or lingual surface is free only in
the upper part of its extent, where it is covered by mucous membrane.
Lower down, the membrane is reflected from it forwards to the base of the
tongue, forming one median fold and two lateral fraenula, or glosso-epiglot-
tidean ligaments. The adherent portion of this surface is also connected
with the posterior surface of the os hyoides by means of a median elastic
tissue named the hyo-epiglottic ligament, and is moreover in contact with
some glands and fatty tissue. The posterior or laryngeal surface of the epi-
glottis, which is free in the whole of its extent, is concavo-convex from
above downwards, but concave from side to side : the lower convexity pro-
jecting backwards into the larynx is named the tubercle or cushion. The
epiglottis is closely covered by mucous membrane, on removing which, the
yellow cartilaginous lamella is seen to be pierced by numerous little pits and
perforations, in which are lodged small glands which open on the surface of
the mucous membrane.
The structure of the cartilages of the larynx. — The epiglottis, together
with the coruicula laryngis and cuneiform cartilages, are composed of what
LIGAMENTS OF THE LARYNX. 909
is called yellow or spongy cartilage, which has little tendency to ossify.
The structure of all the other cartilages of the larynx resembles that of
the costal cartilages, like which, they are very prone to ossification as life
advances.
Ligaments of the larynx. — The epiglottidean ligaments and the union of
the cricoid cartilage with the trachea have been already mentioned : the
other ligaments of the larynx may be divided into thyro-hyoid, crico-
thyroid, and arytenoid groups.
Thyro-hyoid ligaments. — The larynx is connected with the os hyoides by
a broad membrane and by two round lateral ligaments. The thyro-hyoid
membrane, or middle thyro-hyoid ligament, is a broad, fibrous, and somewhat
elastic membrane, which passes up from the whole length of the superior
border of the thyroid cartilage to the os hyoides, where it is attached to
the posterior and upper margin of the obliquely inclined iuferior surface of
the bone. Owing to this arrangement, the top of the larynx, when drawn
upwards, is permitted to slip within the circumference of the hyoid bone,
between which and the upper part of the thyroid cartilage there is occasion-
ally found a small synovial bursa. The thyro-hyoid membrane is thick and
subcutaneous towards the middle line, but on each side becomes thin and
loose, and is covered by the thyro-hyoid muscles. Behind it is the epi-
glottis with the mucous membrane of the base of the tongue, separated,
however, by much adipose tissue and some glands. It is perforated by the
superior laryngeal artery and nerve of each side.
The lateral thyro-hyoid ligaments, placed at the posterior limits of the
thyro-hyoid membrane, are two rounded yellowish cords, which pass up
from the superior cornua of the thyroid cartilage, to the rounded extremities
of the great cornua of the hyoid bone. They are distinctly elastic, and fre-
quently enclose a small oblong cartilaginous nodule, which has been named
cartilago triticea : sometimes this nodule is bony.
Crico-thyroid ligaments. — The thyroid and cricoid cartilages are connected
together by a membranous ligament and synovial articulations. The crwo-
thyroid membrane is divisible into a mesial and two lateral portions. The
mesial portion, broad below and narrow above, is a strong triangular yel-
lowish ligament, consisting chiefly of elastic tissue, and is attached to the
contiguous borders of the two cartilages. Its anterior surface is convex and
is partly covered by the crico-thyroid muscles, and is crossed horizontally by
a small anastomotic arterial arch, formed by the junction of the crico-thyroid
branches of the right and left superior thyroid arteries. The lateral por-
tions are fixed on each side to the inner lip of the upper border of the
cricoid cartilage, between the deep muscles and the mucous membrane :
they become much thinner as they pass upwards and backwards, and are
continuous with the lower margin of the inferior or true vocal cords, becom-
ing blended with them firmly in front.
The crico-thyroid joints, between the inferior cornua of the thyroid carti-
lage and the sides of the cricoid, are two small but distinct articulations,
having each a ligamentous capsule and a synovial membrane. The promi-
nent oval articular surfaces of the cricoid cartilage are directed upwards and
outwards, while those of the thyroid cartilage, which are slightly concave,
look in the opposite direction. The capsular fibres form a stout band be-
hind the joint. The movement allowed is of a rotatory description, the
thyroid cartilage revolving on its inferior cornua, and the axis of rotation
passing transversely through the two joints.
Arytenoid ligaments. — The arytenoid cartilages are connected below with
910 THE LARYNX.
the cricoid cartilage, above with the cornicula, and in front, by means of
fibres contained within the true and false vocal cords, with the thyroid
cartilage.
The crico-arytenoid articulations are surrounded by a series of thin capsu-
lar fibres, which, together with a loose synovial membrane, serve to connect
the convex elliptical articular surfaces on the upper border of the cricoid
cartilage with the concave articular depressions on the bases of the arytenoid
cartilages. There is, moreover, a strong posterior crico-arytenoid ligament
on each side, arising from the cricoid, and inserted into the inner and back
part of the base of the arytenoid cartilage.
The summits of the arytenoid cartilages and the cornicula laryngis have
usually a fibrous and synovial capsule to connect them, but it is frequently
indistinct.
The superior thyro-arytenoid ligaments consist of a few slight fibrous fasci-
culi, contained within the folds of mucous membrane forming the false vocal
cords hereafter to be described, and are fixed in front to the depression
between the alae of the thyroid cartilage, somewhat above its middle, and
close to the attachment of the epiglottis : behind, they are connected to the
tubercles on the rough anterior surface of the aryteuoid cartilages. They are
continuous above with scattered fibrous bundles contained in the aryteno-
epiglottidean folds.
The inferior thyro-arytenoid ligaments, placed within the lips of the
glottis, and forming the true vocal cords, are two bands of elastic tissue
which are attached in front to about the middle of the depression between
the alse of the thyroid cartilage, below the superior cords ; and are inserted
behind into the elongated anterior processes of the base of the arytenoid car-
tilages. These bands are of considerable strength, and consist of closely-
arranged parallel fibres. They are continuous below with the thin lateral
portions of the crico- thyroid membrane.
Interior of the larynx. — The cavity of the larynx is divided into an
upper and a lower compartment by the comparatively narrow aperture of
the glottis, or rima glottidis, the margins of which constitute in their two
anterior thirds the lower or true vocal cords ; and the whole laryngeal
cavity, viewed in transverse section, thus presents the appearance of an
hour-glass, or of two funnels meeting together by their narrower ends.
The upper compartment communicates with the pharynx by the superior
aperture of the larynx, and contains immediately above the rima glottidis
the ventricles and the upper or false vocal cords. The lower compartment
passes inferiorly into the tube of the windpipe without any marked con-
striction or limitation between them (Fig. 638).
The superior aperture of the larynx, by which it communicates with the
pharynx, is a triangular opening, wide in front and narrow behind, the
lateral margins of which slope obliquely downwards and backwards. It is
bounded in front by the epiglottis, behind by the summits of the arytenoid
cartilages and cornicula laryngis with the angular border of mucous mem-
brane crossing the median space between them, and on the sides by two
folds of mucous membrane named the aryteno-epiglottidean folds, which,
enclosing a few ligamentous and muscular fibres, pass forwards from the
tips of the arytenoid cartilages and cornicula to the lateral margins of the
epiglottis (Fig. 637).
In studying the form of the laryngeal cavity and its apertures, it is
proper to become acquainted with the appearances which they present on
examination during life by means of the laryngoscope, and with the relations
LARYXGOSCOPIC VIEW OF THE GLOTTIS.
911
of these to the anatomical structure. On thus examining the superior aper-
ture, there are seen on each side two rounded elevations, corresponding
Fig. 636.— THREE LARYN- Fig. 636.
GOSCOPIO VIEWS OP THE
SUPERIOR APERTURE OF
THE LARYNX AND SUR-
ROUNDING PARTS IN DIF-
FERENT STATES OF THE
GLOTTIS DURING LIFE (from
Czermak).
\ - ,o -f- •&••-
A, the glottis during the
emission of a high note in
singing. B, in easy or quiet
inhalation of air. C, in the
state of widest possible dila-
tation as in inhaling a very
deep breath. The diagrams A ,
B', and C', have been added to
Czermak's figures to show in
horizontal sections of the
glottis the position of the
vocal ligaments and arytenoid
cartilages in the three several
states represented in the other
figures. In all the figures, so
far as marked, the letters in-
dicate the parts as follows,
viz. : I, the base of the tongue ;
et the upper free part of the
epiglottis ; e?, the tubercle
or cushion of the epiglottis ;
ph, part of the anterior wall
of the pharynx behind the
larynx ; in the margin of the
aryteno-epiglottidean fold w,
the swelling of the membrane
caused by the cartilages of Wrisberg ; s, that of the cartilages of Santorini ; a, the tip
or summit of the arytenoid cartilages ; cr, the true vocal cords or lips of the rima glot-
tidis ; cvs, the superior or false vocal cords ; between them the ventricle of the larynx ;
in C, tr is placed on the anterior wall of the receding trachea, and b indicates the com-
mencement of the two bronchi beyond the bifurcation which may be brought into view
in this state of extreme dilatation.
respectively to the cornicula and the cuneiform cartilages ; while in the
middle line in front there is a tumescence of the mucous membrane of the
lower part of the epiglottis, enabling that structure to close the aperture
more accurately when it is depressed, and named the tubercle or cushion of
the epiglottis. The mucous membrane between the arytenoid cartilages is
stretched when they are separated, and folded double when they are
approximated. (Czermak on the Laryngoscope, translated by the New
Sydenham Society.)
On looking down through the superior opening of the larynx, the glottis
or rima glottidis is seen at some distance below, in the form of a long
narrow fissure running from before backwards. It is situated on a level
with the lower part of the arytenoid cartilages, and is bounded by the true
vocal cords, two smooth, strong, and straight folds of membrane projecting
inwards, with their free edges directed towards the middle line. Above the
glottis, another pair of projecting folds is seen, the superior or false vocal
cords, which are much thinner and weaker and less projecting than the
912
THE LARYNX.
inferior, and are arched in form. Bounded by the superior and inferior
vocal cords are two deep oval depressions, one on each side of the glottis,
named the sinuses, or ventricles, of the larynx ; and leading upwards from the
anterior parts of these depressions, external to the superior vocal cords, are
two small culs-de-sac, named the laryngeal pouches or sacculi.
Fig. 637. — PERSPECTIVE VIEW OF THE
PHARYNGEAL OPENING INTO THE LA-
RYNX PROM ABOVE AND BEHIND.
The superior aperture has been much
dilated ; the glottis is in a moderately
dilated condition ; the wall of the pha-
rynx is opened from behind and turned
to the two sides. ], body of the hyoid
bone ; 2, small coi-n«a ; 3, great cornua ;
4, upper and lower cornua of the thyroid
cartilage ; 5, membrane of the pharynx
covering the posterior surface of the
cricoid cartilage ; 6, upper part of the
gullet ; 7, membranous part of the
trachea ; 8, projection caused by the
cartilage of Santorini ; 9, the same be-
longing to the cartilage of Wrisberg ; 10,
aryteno-epiglottidean fold ; 11, cut mar-
gin of the wall of the pharynx ; a, free
part of the epiglottis ; a', its lower
pointed part ; a", the cushion ; 6,
eminence on each side over the sacculus
or pouch of the larynx ; &', the ventricles ;
c, the glottis : the lines on each side
point to the margins or vocal cords.
The superior vocal cords, also
called the false vocal cards, because
they are not immediately concerned
in the production of the voice,
are two folds of mucous membrane,
each of which forms a free cres-
centic margin, bounding the cor-
responding ventricle of the larynx,
the hollow of which is seen on
looking down into the laryngeal cavity, from the superior vocal cords being
separated farther from each other than the inferior cords.
The inferior or true vocal cords, the structures by the vibration of which
the sounds of the voice are produced, occupy the two anterior thirds of the
aperture of the glottis. These cor.ls are not mere folds of mucous mem-
brane, but are strengthened near their free margins by the elastic thyro-
arytenoid ligaments, and further out by the thyro-aryteuoid muscles.
The mucous membrane covering them is so thin and closely adherent as to
show the light colour of the ligaments through it. Their free edges, which
are sharp and straight, and directed upwards, form the lower boundaries of
the ventricles, and are the parts thrown into vibration during the pro-
duction of the voice. Their inner surfaces are flattened, and look towards
each other.
The rima glottidis, an elongated aperture, situated, anteriorly, between
the inferior or true vocal cords, and, posteriorly, between the bases of the
arytenoid cartilages, forms when nearly closed a long narrow slit, slightly
VENTRICLES OF THE LARYNX.
913
wider in the centre ; when moderately open, as in easy respiration, its
shape is that of a long triangle, the pointed extremity being directed for-
wards, and the base being placed behind between the arytenoid cartilages ;
and in its fully dilated condition it has the figure of an elongated lozenge,
the posterior sides of which are formed by the inner sides of the bases of
the arytenoid cartilages, while the posterior angle is truncated. This aper-
ture is the narrowest part of the interior of the larynx ; in the adult male
it measures about eleven lines or nearly an inch in an antero-posterior
direction, and three or four lines across at its widest' part, which may be
dilated to nearly half an inch. In the female, and in males before the age
of puberty, its dimensions are less, its antero-posterior diameter being about
eight lines, and its transverse diameter about two. The vocal ligaments
measure about seven lines in the adult male, and five in the female.
The ventricles, or sinuses of the larynx, situated between the superior and
inferior vocal cords on each side, are narrower at their orifice than in their
interior. The upper margin of each is crescentic, and the lower straight :
the outer surface is covered by the
upper fibres of the corresponding Fig 633_
thyro-arytenoid muscle.
Fig. 638. — ANTERIOR HALF OF A TRANS-
VERSE VERTICAL SECTION THROUGH THE
LARYNX NEAR ITS MIDDLE.
In order to bring the deepest part of one
of the sacculi into view, the section is car-
ried somewhat farther forward on the right
side : the space between the horizontal
dotted lines marked 1, comprises the upper
division of the laryngeal cavity ; that
marked 2, corresponds to the middle cavity
or that of the ventricles ; that marked 3,
indicates the lower division of the laryngeal
cavity, continued into 4, a part of the
trachea ; e, the free part of the epiglottis ;
e', its cushion ; h, the divided great cornua
of the hyoid bone ; ht, thyro-hyoid mem-
brane ; t, cut surface of the divided thyroid
cartilage ; c, that of the cricoid cartilage ;
r, first ring of the trachea ; ta, superior
and inferior parts of the thyro-arytenoid
muscle ; vl, thyro-arytenoid ligament in
the true vocal cord covered by mucous
membrane at the rima glottidis ; s, the
ventricle ; above this, the superior or false
cords or margin of the folds above the ven-
tricles ; a', the sacculus or pouch opened on
the right side.
The small culs-de-sac named the laryngeal pouches lead from the anterior
part of the ventricles upwards, for the space of half an inch, between the
superior vocal cords on the inner side, and the thyroid cartilage on the outer
side, reaching as high as the upper border of that cartilage at the sides of
the epiglottis. The pouch is conical in shape, and curved slightly backwards.
Its opening into the ventricle is narrow, and is generally limited by two
folds of the lining mucous membrane. Numerous small glands, sixty or
seventy in number, open into its interior, and it is surrounded by a quan-
tity of fat. Externally to the fat, this little pouch receives a fibrous
investment, which is continuous below with the superior vocal cord. Over
3 o
914
THE LARYNX.
its laryngeal side and upper end is a thin lajer of muscular fibres (com-
pressor sacculi laryngis, arytaeno-epiglottideus inferior, Hilton) connected
above with those found in the aryteno-epiglottidean folds. The upper fibres
of the thyro-arytenoid muscles pass over the outer side of the pouch, a
few being attached to its lower part. The laryugeal pouch is supplied
abundantly with nerves, derived from the superior laryngeaL
Muscles of the Larynx.
Besides certain extrinsic muscles already described — viz., the sterno-hyoid,
omo-hyoid, stern o- thyroid, and thyro-hyoid muscles, together with the
muscles of the suprahyoid region, and the middle and inferior constrictors
of the pharynx, all of which act more or less upon the entire larynx — there
are certain intrinsic muscles which move the different cartilages upon one
another, and modify the size of the apertures and the state of tension of
the soft parts of the larynx. These intrinsic muscles are the crico-thyroid,
the posterior and lateral crico-arytenoid, the thyro-arytenoid, the arytenoid,
and the aryteno-epiglottidean, together with certain other slender muscular
fasciculi. All these muscles, except the arytenoid, which crosses the middle
line, are in pairs.
The crico-thyroid muscle is a short thick triangular muscle, seen on the
front of the larynx, situated on the fore part and side of the cricoid cartilage.
It arises by a broad origin from the cricoid cartilage, reaching from the
Fig. 639.
Fig. 639. — LATERAL VIEW OP THE CARTILAGES
OP THE LARYNX WITH THE CRICO-THYROID
MUSCLE (after Willis).
8, thyroid cartilage; 9, cricoid; 10, crico-
thyroid muscle ; 11, crico-thyroid ligament or
membrane ; 12, upper rings of the trachea.
median line backwards upon the lateral
surface, and its fibres, passing obliquely
upwards and outwards and diverging
slightly, are inserted into the lower bor-
der of the thyroid cartilage, and into the
anterior border of its inferior cornu.
The lower portion of the muscle, the
fibres of which are nearly horizontal, and
are inserted into the inferior cornu, is
usually distinct from the rest. Some
of the superficial fibres are almost
always continuous with the inferior con-
strictor of the pharynx. The inner
borders of the muscles of the two sides
are separated in the middle line by a triangular interval, broader above
than below, and occupied by the crico-thyroid membrane.
The posterior crico-arytenoid muscle, situated behind the larynx, beneath
the mucous membrane of the pharynx, arises from the broad depression on
the corresponding half of the posterior surface of the cricoid cartilage. From
this broad origin its fibres converge upwards and outwards to be inserted
into the outer angle of the base of the arytenoid cartilage, behind the
attachment of the lateral crico-arytenoid muscle. The upper fibres are short
MUSCLES OF THE LARYNX.
915
and almost horizontal ; the middle are the longest, and run obliquely ;
whilst the lower or external fibres are nearly vertical.
Fig. 640.
Fig. 640. — VIEW OF THE LARYNX AND PART OF
THE TRACHEA FROM BEHIND, WITH THE MUS-
CLES DISSECTED.
h, the body of the hyoid bone ; e, epiglottis ;
t, the posterior borders of the thyroid cartilage ;
c, the median ridge of the cricoid ; a, upper
part of the arytenoid ; s, placed on one of the
oblique fasciculi of the arytenoid muscle ; b,
left posterior crico-arytenoid muscle ; r, ends of
the incomplete cartilaginous rings of the trachea ;
I, fibrous membrane crossing the back of the
trachea ; n, muscular fibres exposed in a part.
In connection with the posterior crico-
arytenoid muscle, may be mentioned an
occasional small slip in contact with its lower
border, viz., the kerato-cricoid muscle of
Merkel. It is a short and slender bundle,
arising from the cricoid cartilage near its
lower border, a little behind the inferior
cornu of the thyroid cartilage, and passing
obliquely outwards and upwards to be inserted
into that process. It usually exists on only
one side. Turner found it in seven out of
thirty-two bodies. It is not known to be of
any physiological significance. (Merkel, Anat.
und Phys. des Menschl. tStimm-und-Sprach-
organs, Leipzig, 1857; Turner in Month. Med.
Journal, Feb. 1860.)
The lateral crico-arytenoid muscle, smaller than the posterior, and of an
oblong form, is in a great measure hidden by the ala of the thyroid carti-
lage. It arises from the upper border of the side of the cricoid cartilage, its
Fig. 641,
Fig. 641. — DIAGRAMMATIC VIEW FROM ABOVE OF
THE DISSECTED LARYNX (after Willis).
1, aperture of the glottis; 2, arytenoid carti-
3, vocal cords ; 4, posterior crico-arytenoid
muscles; 5, right lateral crico-arytenoid muscle,
that of the left side being removed ; 6, arytenoid
muscle ; 7, thyro-arytenoid muscle of the left
side, that of the right side being removed ; 8,
upper border of the thyroid cartilage ; 9, back of
the cricoid cartilage ; 13, posterior crico-arytenoid
ligament.
origin extending as far back as the articular
surface for the arytenoid cartilage. Its
fibres, passing obliquely backwards and up-
wards, and the anterior or upper ones being
the longest, are attached to the external
process or outer side of the base of the arytenoid cartilage and to the
adjacent part of its anterior surface, in front of the insertion of the
posterior crico-arytenoid muscle.
This muscle lies in the interval between the ala of the thyroid cartilage
3 o 2
916
THE LA11YNX.
and the interior of the larynx, being lined within by the mucous membrane
of the larynx. Its anterior part is covered by the upper part of the crico-
thyroid muscle. The upper part is in close contact and indeed is sometimes
blended with the thyro-arytenoid muscle.
The thyro-arytenoid is a broad flat muscle situated above the lateral crico-
aryteuoid. It is thick below and in front, and becomes thinner above and
behind. It consists of several muscular fasciculi, which arise in front from
the internal surface of the thyroid cartilage, adjacent to the lower two-thirds
of the angle formed by the junction of the two alee. They extend almost
horizontally backwards and outwards to reach the base of the arytenoid
cartilage. The lower portion of the muscle, which forms a thick fasciculus,
receives a few additioual fibres from the posterior surface of the crico-
thyroid membrane, and is inserted into the anterior projection on the base
of the aryteuoid cartilage and to the adjacent part of the surface close to the
insertion of the lateral crico-arytenoid muscle. The thinner portion of the
thyro-arytenoid muscle is inserted higher up on the anterior surface and
Fig. 642. Fig. 642. — VIEW OP THE INTERIOR
OF THK LEFT HALF OF THE LA-
RYNX (after Hilton).
a, left arytenoid cartilage ; c, c,
divided surfaces of the cricoid car-
tilage ; t, thyroid cartilage ; e,
epiglottis; v, left ventricle of the
larynx ; ?•, left inferior or true
vocal cord ; s, placed on the inner
wall of the laryngeal pouch ; 6,
aryteno-epiglottidean muscle ; /,
interior of the trachea.
outer border of the arytenoid
cartilage. The lower portion
of the muscle assists in the
formation, or at least contri-
butes to the support, of the
true vocal cord, lying parallel
with the rim a glottidis, im-
mediately on the outer side
of the inferior thyro-arytenoid
ligament, with which it is in-
timately connected, and into
the outer surface of which
some of its fibres are inserted.
The upper thin portion, ex-
ternal to the lower, lies upon
the laryngeal pouch and ventricle, close beneath the mucous membrane.
The entire muscle may be dissected indeed from the interior of the larynx,
by raising the mucous membrane of the sinus and vocal cord. Fibres from
this muscle pass round the border of the arytenoid cartilage, and become
continuous with some of the oblique fibres of the arytenoid muscle, to be
presently described.
Santorini described three thyro-arytenoid muscles, an inferior and a middle, which
are constant, and a superior, which is sometimes present. The fibres of the superior
fasciculus, when present, arise nearest to the notch of the thyroid cartilage, and are
MUSCLES OF THE LARYNX.
917
attached to the upper part of the arytenoid cartilage. This is named by Scemmerring
the small thyro-arytenoid, whilst the two other portions of the muscle constitute the
great thyro-arytenoid of that author.
Arytenoid and aryteno-epiglotlidean muscles. — When the mucous mem-
brane is removed from the back of the arytenoid cartilages, a thick band of
transverse fibres constituting the arytenoid muscle is laid bare, and on the
surface of this are seen two slender decussating oblique bundles, formerly
described as portions of the arytenoid muscle (arytsenoideus obliquus), but
now more generally considered as parts of the aryteuo-epiglottidean muscles,
with which they are more closely associated both in the disposition of their
fibres and in their action. The arytenoid muscle passes straight across, and iU
fibres are attached to the whole extent of the concave surface on the back of
each aryteuoid cartilage. The aryteno-epiglottidean muscles arising near the
inferior and outer angles of the arytenoid cartilages, decussate one with the
other, and their fibres are partly attached to the upper and outer part of the
opposite cartilage, partly pass forwards in the aryteno-epiglottideau fold,
and partly join the fibres of the thyro-arytenoid muscle.
A few fibres associated with the anterior and upper part of the thyro-
arytenoid muscle have been described as constituting a thyro-epiylottidean
muscle.
Fig. 643.
Fig. 643. — OUTLINE OF THE RIGHT HALF
OF THE CARTILAGES OP THE LARYNX AS
SKEN FROM THE INSIDE, WITH THE THYRO-
ARYTENOID LIGAMENT, TO ILLUSTRATE
THE ACTION OF THE CRICO-THYROID
MUSCLE.,
t, cut surface of the thyroid cartilage in
the middle anteriorly ; c, c, the same of the
cricoid cartilage before and behind ; a, the
inner surface of the right arytenoid carti-
lage ; a', its anterior process ; s, the right
cartilage of Santorini ; c v, the thyro-ary-
tenoid ligament ; the position of the lower
cornu of the thyroid cartilage on the out-
side of the cricoid is indicated by a dotted
outline, and r indicates the point or axis
of rotation of the one cartilage on the other ;
cth, indicates a line in the principal direc-
tion of action of the crico-thyroid muscle;
cap, the same of the posterior crico-
arytenoid muscle ; the dotted line, of which
t' indicates a part, represents the position
into which the thyroid cartilage is moved
by tlie action of the crico-tbyroid muscle ;
if the arytenoid cartilages are fixed by
muscles acting in the direction of cap,
the vocal ligaments will be elongated and
rendered tense by contraction of the crico-
thyroid muscles, as indicated by cv'.
Actions of the intrinsic muscles of the larynx. — The crico-thyroid muscles produce
the rotation forwards and downwards of the thyroid cartilage on the cricoid, which is
permitted by the crico-thyroid articulations. In this movement the arytenoid carti-
lages, being attached to the cricoid cartilage at a level considerably above the axis of
rotation, have their distance from the fore part of the thyroid cartilage increased, and
therefore, the crico-thyroid muscles increase the tension of the vocal cords. The
thyro-arytenoid muscles are, in their lower parts, the opponents of the crico-thyroid,
raising the fore part of the thyroid cartilage and decreasing the tension of the vocal
cth/
918 THE LARYNX.
cords ; the upper parts of these muscles, being attached higher up on the arytenoid
cartilages, depress them.
The lateral crico-arytenoid muscles, by pulling forwards the outer angles of the
arytenoid cartilages, approximate the vocal cords to the middle line. The posterior
crico-arytenoid muscles pull backwards the outer angles of the arytenoid cartilages, and
thus draw asunder the posterior extremities of the vocal cords, and dilate the glottis
to its greatest extent ; they are likewise the elevators of the arytenoid cartilages,
being inserted above the articulation.
The arytenoid muscle draws the arytenoid cartilages together, and, from the struc-
ture of the crico-arytenoid joints, this approximation when complete is necessarily
accompanied with depression. The aryteno-epiglottidean muscles at once depress and
approximate the arytenoid cartilages, which they include in their embrace, and draw
down the epiglottis, so as to contract the whole superior aperture of the larynx.
With the aid of the laryngoscope it may be seen that in ordinary breathing the rima
glottidis is widely op«n, and that in vocalisation the vocal cords come closely together ;
which is effected principally, no doubt, by the action of the lateral crico-arytenoid
muscles, assisted by the arytenoid and perhaps by the thyro-arytenoid, and accom-
panied with a varying amount of contraction of the crico-thyroid muscles. The
regulation of the tension of the vocal cords and of the width of the aperture of the
glottis, in the production of high and low pitched notes, is probably accomplished by
the crico-thyroid and thyro-arytenoid muscles. The movement of the thyroid on the
cricoid cartilage, effected by these muscles during the passage of the voice from one
extreme of the scale to the other, may be detected by placing the tip of a finger over
the crico-thyroid ligament. The arytenoid and aryteno-epiglottidean muscles come
into action in spasmodic closure of the upper aperture of the larynx ; the complete
descent of the epiglottis, however, can only take place when the tongue is retracted
as in the act of swallowing.
The manner in which the larynx is affected by the extrinsic muscles, in the acts of
deglutition and vocalisation, has been mentioned at pages 191 and 193.
It is remarked by Henle that, with the exception of the crico-thyroid and posterior
crico-arytenoid, the muscles of the larynx, namely, those " which lie in the space
enclosed by the laminae of the thyroid cartilage, and above the cricoid, the fibres of
which are substantially horizontal, may be regarded in their totality as a kind of
sphincter. Such a sphincter is found in its simple form embracing the entrance of
the larynx in reptiles ; and the complication which it attains in the higher vertebrates
arises, like the complication of the muscles generally, from the fibres finding various
points of attachment in their course, by which means they are broken up and
divided."
The mucous membrane and glands of the larynx. — The laryngeal mucous
membrane is thin and of a pale pink colour. la some situations it adheres
intimately to the subjacent parts, especially on the epiglottis, and still more
in passing over the true vocal cords, on which it is extremely thin and most
closely adherent. About the upper part of the larynx, above the glottis,
it is extremely sensitive. In or near the aryteno-epiglottidean folds it
covers a quantity of loose areolar tissue, which is liable in disease to in-
filtration, constituting oedema of the glottis. Like the mucous membrane
in the rest of the air-passages, that of the larynx is covered in the greater
part of its extent with a columnar ciliated epithelium, by the vibratory
action of which the mucus is urged upwards. The cilia are found higher
up in front than on each side and behind, reaching in the former direction
as high as the widest portion of the epiglottis, and in the other directions to
a line or two above the border of the superior vocal cords : above these
points the epithelium loses its cilia, and gradually assumes a squamous
form, like that of the pharynx and mouth. Upon the vocal cords also the
epithelium is squamous, although both above and below them it is ciliated.
Glands. — The lining membrane of the larynx is provided with numerous
glands, which secrete an abundant mucus ; and the orifices of which may
DEVELOPMENT AND GROWTH OF THE LARYNX. 919
be seen almost everywhere, excepting upon and near the true vocal cords.
They abound particularly upon the epiglottis, in the substance of which are
found upwards of fifty small compound glands, some of them perforating
the cartilage. Between the anterior surface of the epiglottis, the hyoid bone,
and the root of the tongue, is a mass of yellowish fat, erroneously named
the epiglottidean gland, in or upon which some real glands may exist.
Another collection of glands, named a/rytenoid, is placed within the fold of
mucous membrane in front of each arytenoid cartilage, from which a series
may be traced forwards, along the corresponding superior vocal cord. The
glands of the laryngeal pouches have already been described.
Vessels and Nerves of the Larynx.
The arteries of the larynx are derived from the superior thyroid (p. 343), a branch of
the external carotid, and from the inferior thyroid (p. 371), a branch of the subclavian.
The veins join the superior, middle and inferior thyroid veins. The lymphatics are
numerous, and pass through the cervical glands. The nerves are supplied from the
superior laryngeal and inferior or recurrent laryngeal branches of the pneumogastric
nerves, joined by branches of the sympathetic. The superior laryngeal nerves supply
the mucous membrane, and also the crico-thyroid muscles, and in part the arytenoid
muscle. The inferior laryngeal nerves supply, in part, the arytenoid muscle, and all
the other muscles, excepting the crico-thyroid.
The superior and inferior laryngeal nerves of each side communicate with each other
in two places, viz., at the back of the larynx, beneath the pharyngeal mucous mem-
brane, and on the side of the larynx, under the ala of the thyroid cartilage (p. 622).
DEVELOPMENT AND GROWTH OP THE LARYNX.
Development. — The rudimentary larynx consists, according to Valentin, of two
slight enlargements having a fissure between them, and embracing the entrance from
the pharynx into the trachea. According to Reichert, the rudiments of the arytenoid
cartilages are the first to appear. Rathke, however, states that all the true cartilages
are formed at the same time, and are recognisable together as the larynx enlarges, the
epiglottis only appearing later. In the human embryo, Fleischmann could not detect
the cartilages at the seventh week, though the larynx was half a line in length, but at
the eighth week there were visible the thyroid and cricoid cartilages, consisting at
that period of two lateral halves, which are afterwards united together in the sixth
month. Kblliker, however, states that Fleischmann had been deceived by the presence
of a deep groove, and that by making transverse sections he ascertained that those
cartilages are single from the first.
Growth. — During childhood the growth of the larynx is very slow. Richerand
found that there was scarcely any difference between the dimensions of this organ in
a child of three and in one of twelve years of age. Up to the age of puberty the larynx
is similar in the male and female, the chief characteristics at that period being the
small size and comparative slightness of the organ, and the smooth rounded form of
the thyroid cartilage in front. In the female these conditions are permanent, excepting
that a slight increase in size takes place. In the male, on the contrary, at the time
of puberty, remarkable changes rapidly occur, and the larynx becomes more prominent
and more perceptible at the upper part of the neck. Its cartilages become larger,
thicker, and stronger, and the alee of the thyroid cartilage project forwards in front so
as to form at their union with one another, with an acute angle, the prominent ridge of
thepomum Adami. At the same time, the median notch on its upper border is consider-
ably deepened. In consequence of these changes in the thyroid cartilage, the distance
between its angle in front and the arytenoid cartilages behind becomes greater, and
the chordae vocales are necessarily lengthened. Hence the dimensions of the glottis,
which, at the time of puberty, are increased by about one-third only in the female, are
nearly doubled in the male, and the adult male larynx becomes altogether one-third
larger than that of the female.
Towards the middle of life the cartilages of the larynx first show a tendency to
920
THE THYROID BODY.
ossification ; this commences first in the'thyroid cartilage, then appears in the cricoid,
and lastly in the arytenoid cartilages. In the thyroid cartilage the ossification usually
begins at the cornua and posterior borders ; it then gradually extends along the whole
inferior border, and subsequently spreads upwards through the cartilage. The cricoid
cartilage first becomes ossified at its upper border upon each side, near the two pos-
terior articular eminences, and the ossification invades the lateral parts of the cartilage
before encroaching on it either in front or behind. The arytenoid cartilages become
ossified from below upwards.
DUCTLESS GLANDS ON THE LARYNX AND TRACHEA.
1. THE THYROID BODY.
The thyroid body or gland is a soft reddish and highly vascular organ,
situated in the lower part of the neck, embracing the front and sides of the
upper part of the trachea, and reaching up to the sides of the larynx. It
belongs, like the spleen, to the series of structures known as ductless glands ;
and, although its precise function is unascertained, there is reason to believe
that it is in some way connected with the elaboration of the blood.
The thyroid body is of an irregular, semilunar form, consisting of two
lateral lolest united together towards their lower ends by a transverse por-
tion named the isthmus. Viewed as a whole, it is convex on the sides and
in front, forming a rounded projection upon the trachea and larynx. It
is covered by the sterno-hyoid, sterno-thyroid, and omo-hyoid muscles, and
behind them it comes into contact with the sheath of the great vessels of
the neck. Its deep surface is concave where it rests against the trachea
Fig. 644.
Fig. 614. —SKETCH SHOWING THE FORM AND POSITION
OF THE THYROID BODY. 4
The larynx and surrounding parts are viewed from
before ; on the right side the muscles covering the
thyroid body are retained, on the leftside they are
removed ; h, hyoid bone ; th, right thryo-hyoid mus-
cle ; oh, omo-hyoid; sh, sterno-hyoid; st, sterno-
thyroid ; c, on the crico-thyroid membrane above the
cricoid cartilage, points by a dotted line to the right
crico-thyroid muscle; tr, the trachea; as, the oeso-
phagus appearing behind and slightly to the left of the
trachea ; tt the right lobe of the thyroid body partially
seen between the muscles ; t', the left lobe entirely
exposed; i, the isthmus; It, the fibrous or muscular
band termed levator thyroidese, which is occasionally
found in the middle line or to the left side, and which
existed in the case from which the figure was taken.
and larynx. It usually extends so far back as
to touch the lower portion of the pharynx, and
on the left side the oesophagus also.
Each lateral lobe measures usually two inches
or upwards in length, an inch and a quarter
in breadth, and three-quarters of an inch in
thickness at its largest part, which is below its
middle : the right lobe is usually a few lines longer and wider than the left.
The general direction of each lobe is, from below, obliquely upwards and
backwards, reaching from the fifth or sixth ring of the trachea to the pos-
terior border of the thyroid cartilage, of which it covers the inferior cornu
and adjoining part of the ala. The upper end of the lobe, which is thinner,
FORM AND STRUCTURE OF THE THYROID BODY.
921
and sometimes called the cornu, is usually connected to the side of the
thyroid and cricoid cartilages by areolar tissue.
The transverse part, or isthmus, which connects the two lateral lobes to-
gether a little above their lower ends, measures nearly half an inch in
breadth, and from a quarter to three-quarters of an inch in depth ; it com-
monly lies across the third and fourth rings of the trachea, but is very
inconstant in size, shape, and position, so that the portion of trachea which
is covered by it is subject to corresponding variations. From the upper part of
the isthmus, or from the adjacent portion of either lobe, but most frequently
the left, a conical portion of the thyroid body, named, from its shape and
position, the pyramid, or middle lobe, often proceeds upwards to the middle
of the hyoid bone, to which its apex is attached by loose fibrous tissue.
Commonly this process lies somewhat to the left ; occasionally it is thicker
above than below, or is completely detached, or is split into two parts :
sometimes it appears to consist of fibrous tissue only. In many cases, mus-
cular fasciculi, most frequently derived from the thyro-hyoid muscle, but
occasionally independent, descend from the hyoid bone to the thyroid gland
or its pyramidal process. They are known as the levator glanduloe thy-
roidece. It sometimes, though rarely, happens that the isthmus is alto-
gether wanting, the lateral lobes being then connected by areolar or fibrous
tissue only.
The weight of the thyroid body varies ordinarily from one to two ounces.
It is always larger in the female than in the male, and appears in many of
the former to undergo a periodical increase about the time of menstruation.
The thyroid body, moreover, is subject to much variation of size, and is,
occasionally, the seat of enormous enlargement, constituting the disease
called goitre. The colour of the thyroid body is usually of a dusky brownish
red, but sometimes it presents a yellowish hue.
Fig. 645.— MAGNIFIED VIEW OF Fig. 6 in.
SEVERAL VESICLES FROM THE
THYKOID GLAND OF A CHILD (from
Kolliker). *f°
a, connective tissue between the
vesicles ; 6, capsule of the vesicles ;
c, their epithelial lining.
Structure. — The texture of
this organ is firm, and to the
naked eye appears coarsely
granular. It is invested with
a thin transparent layer of
dense areolar tissue, which con-
nects it with the adjacent parts,
surrounds and supports the
vessels as they enter it, and
imperfectly separates its sub-
stance into small masses of
irregular form and size. The interstitial areolar tissue is free from fat, and
contains elastic fibres.
When the thyroid body is cut into, a yellow glairy fluid escapes from the
divided substance, which is itself found to contain multitudes of closed
vesicles, composed of a simple external capsular membrane, and containing
922
THE THYROID BODY.
a yellow fluid, with corpuscles resembling cell-nuclei and sometimes nu-
cleated cells floating in it. These vesicles are surrounded by capillary ves-
sels, and are held together in groups or imperfect lobules by areolar tissue.
Their size varies from ^-^th of an inch to that of a millet-seed, so as to be
visible to the naked eye, — the size varying, however, in different individuals,
more than in the same thyroid body. The vesicles are spherical, oblong, or
flattened, and are perfectly distinct from each other ; the corpuscles within
them are in the foetus and young subject disposed in close apposition
and like a single epithelial layer on the inner side of the vesicles, but
for the most part detach themselves in the progress of growth. The fluid
coagulates by the action of heat or of alcohol, preserving, however, it*
transparency. According to recent analyses, the substance of the thyroid
body consists principally of albumen with traces of gelatine, stearine, oleine,
and extractive matter, besides alkaline and earthy salts and water. The
salts are chloride of sodium, a little alkaline sulphate, phosphates of potash,
lime and magnesia, with
Fig. 646. some oxide of iron.
A
Fig. 646. — TESICLES OP THE
THYROID GLAND ENLARGED
AND CONTAINING COLLOID
MATTER (from Kolliker). ^
One of the most fre-
quent pathological changes
to which the thyroid body
is subject consists in the
accumulation within its ve-
sicles of colloid substance :
this may occur without
giving rise to very great
enlargement of these vesi-
cles, but in certain forms
of goitre it distends them
to an enormous degree.
Vessels. — The arteries of the thyroid body (pp. 346 and 371) are the superior and
inferior thyroids of each side, to which is sometimes added a fifth vessel named the
lowest thyroid of Neubauer and Erdmann (p. 340). The arteries are remarkable for
their large relative size, and for their frequent and large anastomoses; they terminate
in a capillary network, upon the outside of the closed vesicles. The veins, which are
equally large, ultimately form plexuses on the surface, from which a superior, middle,
and inferior thyroid vein (pp. 453 and 460) are formed on each side. The superior
and middle thyroid veins open into the internal jugular; the inferior veins emanate
from a plexus formed in front of the trachea, and open on the right side into the
superior cava, and on the left into the brachio-cephalic vein. The lymphatics of the
thyroid body are extremely numerous and large, and are supposed to convey into the
blood the products formed within the organ.
Nerves. — The nerves are derived from the pneumogastric, and from the middle and
inferior cervical ganglia of the sympathetic.
Development. — Eemak states that the thyroid body is developed from the anterior
wall of the pharynx. In a human embryo at the third month, Kolliker found the
thyroid body consisting of isolated vesicles, with rounded cells in their interior. The
multiplication of these vesicles takes place, according to Kolliker, either by constric-
tion and subsequent division of one vesicle into two, or by a process of gemmation.
The transverse part of the gland is said to be developed subsequently to the two lateral
FORM AND POSITION OF THE THYMUS GLAXD.
923
lobes. In the foetus, and during early infancy, this organ is relatively larger than in
after life ; its proportion to the weight of the body in the new-born infant being that
of 1 to 240 or 400, whilst at the end of three weeks it becomes only 1 to 1160, and
in the adult 1 to 1800 (Krause). In advanced life the thyroid body becomes in-
durated, and frequently contains earthy deposit; its vesicles also attain a very large
size.
2. THE THYMUS GLAND.
The thymus gland or body (glandula thymus, corpus thymicum) is a tem-
porary organ which reaches its greatest size at about the end of the second
year, after which period it ceases to grow, and is gradually reduced to a
mere vestige. Its function, like that of the thyroid body, is unknown,
although it is probable that it is in some way connected with, the elaboration
of the blood in infancy. When examined in its mature state in an infant
under two years of age, it appears as a narrow elongated glandular-looking
body, situated partly in the thorax, and partly in the lower region of the
neck : below, it lies in the anterior mediastiual space, close behind the ster-
num, and in front of the great vessels and pericardium ; above it reaches
upwards upon the trachea in the neck. Its colour is greyish, with a pinkish
tinge ; its consistence is soft and pulpy, and its surface appears distinctly
lobulated. It consists of two lateral parts, or lobes, which touch each other
along the middle line, and are nearly symmetrical in form, though generally
unequal in size, sometimes the left, and at other times the right lobe being
the larger of the two. An intermediate lobe often exists between the two
lateral ones, and occasionally the whole body forms a single mass. The
forms of the smaller lobules also differ on the two sides.
Fig. 647. — ONE LOBE OF THE HUMAN THYMUS Fig. 647.
GLAND (from Koliiker).
The lower part presents a large cavity which
has been opened, and within it are seen nume-
rous apertures leading into the smaller lobes.
Each lateral lobe is of an elongated
triangular form, its base being directed
downwards. The summit, or upper ex-
tremity, usually mounts up into the
neck, reaching as high as to the lower
border of the thyroid body. The base
rests on the upper part of the pericar-
dium, to which it is connected by areolar
tissue. The anterior surface, slightly
convex, is covered by the first and the
upper part of the second piece of the
sternum, reaching, in the infant at birth,
as low down as the level of the fourth
costal cartilage. It is attached to the
sternum by loose areolar tissue, but
opposite the upper part of that bone is
separated from it by the origins of the sterno-hyoid and sterno-thyroid
muscles, which also cover it in the neck. The posterior surface, some-
what concave, rests, in the thorax, upon part of the pericardium, upon the
front of the aortic arch and the large arteries arising from it, and also on
924 THE THYMUS GLAND.
the left innominate vein, some areolar tissue being interposed between it
and these parts. In the neck, it lies upon the front and corresponding
side of the trachea. Its external border is in contact with the corresponding
layer of the mediastinal pleura, near the internal mammary artery, and
higher up (in the neck), with the carotid artery, or its sheath. The internal
border is in close contact with that of the opposite lateral lobe. The
dimensions of the thymus vary according to its stage of development. At
birth it measures above two inches in length, an inch and a half in width
at its lower part, and about three or four lines in thickness. Its weight at
that period is about half an ounce. Its specific gravity, which is at first
about 1 -050, diminishes as the gland continues to waste.
Chemical Composition. — The substance and fluid of the thymus contain
nearly eighty per cent, of water. Its solid animal constituents are com-
posed essentially of albumen and fibrin in large quantities, mixed witli
gelatine and other animal matter. The salts are principally alkaline and
earthy phosphates, with chloride of potassium.
Structure. — The lateral halves or lobes of the thymus gland are each
surrounded by a proper investment of thin areolar tissue, which encloses
in a common envelope the smaller masses composing it. This tissue being
removed, the substance of the gland is found to consist of numerous com-
pressed lobules, the most of them from two to five lines in diameter, con-
nected by a more delicate intervening areolar tissue. These primary
lobules, as they may be called, are each made up externally of smaller or
secondary lobules, of a compressed pyriform shape, placed close together
with their bases outwardly, and are arranged round an elongated central
stem (reservoir of the thymus, Cooper), running through each lateral half of
the gland, and more or less spirally twisted.
On making a section of the thymus, there is obtained a milky substance
consisting of fluid rich in nuclei and small nucleated cells. The walls
both of the lobules and the larger stems are limited by a fine homogeneous
membrane (Simon) ; the substance in the interior of this appears at first
sight to be entirely composed of corpuscles of the kind just mentioned,
varying in diameter from -gjuo^ to Wofi**1 °^ an incn> an(i having the
appearance of free nuclei ; but, on closer examination, according to Kolli-
ker and His, seen to be mostly contained within delicate cells. The sub-
stance contained within the limiting membrane is not, however, a mere
fluid with corpuscles, but possesses a delicate reticulum of connective tissue,
and, as was first pointed out by Kolliker, likewise capillary blood-vessels,
resembling in this respect the substance which occupies the interior of
Peyer's glands.
According to Astley Cooper the central stem of the thymus presents a
continuous cavity, the ramifications of which pass into both primary and
secondary lobules. The existence of a central cavity has been since doubted
by some and aflirmed by others ; the difficulty, however, may now be re-
garded as cleared up, since the discovery of connective tissue and blood-vessels
within the lobulated structure ; for it is admitted that, in the centres of the
lobules, sublobules, and central stem, the capillaries and reticulum of con-
nective tissue are deficient and the corpuscles most abundant, while on the
other hand it is equally certain that there is no cavity bounded by epithelial
lining. Considered in relation to development, Cooper's view is correct ; for
it has been shown by Simon that the primitive form of the thymus gland is
a linear tube, from which, as it grows, lateral branched diverticula subse-
quently bud out, but that in the mature thymus this tube becomes obscure.
STRUCTURE OF THE THYMUS GLAND.
925
He is of opinion that the central cavity described and figured by Cooper is
preternaturally enlarged, owing to over- distension ; but that, nevertheless, all
the parts of each lateral mass of the thymus are connected with a single
Fig. 648.— TRANSVERSE SECTION OP A LOBULE
OP AN INJECTED INFANTILE THYMUS GLAND
(from Kolliker). ^
a, capsule of connective tissue surrounding
the lobule ; 6, membrane of the glandular
vesicles ; c, cavity of the lobule, from which
the larger blood-vessels are seen to extend to-
wards and ramify in the spheroidal masses of
the lobule.
common cavity. (Astley Cooper, Ana-
tomy of the Thymus Gland, Lond.,
1832 ; Simon, Physiological Essay on
the Thymus Gland, Lond., 1845 ; His,
on the Lymphatics of the Thymus, in
Zeitsch. f. wissensch. Zoologie, X. and
XI. ; Kolliker and Henle in their respec-
tive Handbooks.)
Fig. 648.
Vessels. — The arteries of the thymus are
derived from various sources, viz., from the
internal mammary arteries, the inferior and
superior thyroid, the subclavian and carotid
arteries. They terminate in capillary vessels, which form a vascular envelope around
and within each vesicle.
The veins pursue a different course from the arteries, and, for the most part, open
into the left innominate vein.
The lymphatics are large. A ccording to the observations of His on the calf, the
larger blood-vessels passing to the central canal are each accompanied by two or more
lymphatic stems. He finds that these arise from an interlobular plexus of lymphatic
spaces destitute of walls, and that this plexus receives its roots from the interior of the
lobules; and he advances the opinion that they communicate directly with the central
spaces of the lobules; he has not, however, actually observed such a connection.
The nerves are very minute. Haller thought they were partly derived from the
phrenic nerves, but according to Cooper, no filaments from these nerves go into the
gland, though they reach the investing capsule, as does also a branch from the
descendens noni. Small filaments, derived from the pneumogastric and sympathetic
nerves, descend on the thyroid body, to the upper part of the thymus. Sympathetic
nerves also reach the gland along its various arteries.
Development. — The early development of the thymus has been carefully studied by
Simon, whose researches were chiefly conducted in the embryos of swine and oxen.
In embryos about half an inch in length, it may be seen with the aid of a high
magnifying power; and in those of one and a half inch, with the aid of a simple lens.
When first distinguishable, it consists of a simple tube closed in all directions, lying
along the carotid vessels. The contents'of this tube are granular, but do not show
regular corpuscles; its walls are delicate and homogeneous. The tube has no con-
nection with the respiratory mucous membrane, as was supposed by Arnold; and so
soon as it is discoverable, it is found to be perfectly distinct from the thyroid body.
At intervals along the sides of this tube small vesicles bud out, so as to form lateral
diverticula, which contain nucleated corpuscles, and which go on subsequently
branching out into groups of two or four, — the formation of the permanent vesicles
being merely the last repetition of this process. In the human foetus at the seventh
week, Kolliker has seen the thymus lobate at its lower end, and single above; at
about the ninth week, the thymus consists of two minute elongated parallel parts
926 THE URINARY ORGANS.
lying chiefly on the upper part of the pericardium, and presenting under the micro-
scope a distinct tubulo-vesicular structure filled with polygonal cells; at the twelfth
week the thymus is broad, and its surface is entirely covered with lobules ; it then
increases rapidly until birth, but not with uniform rapidity, for it grows especially
during the seventh, eighth, and ninth months of intra-uterine existence.
A fter birth, the thymus, as already stated, continues to grow to near the end of the
second year. According to the observations of Haugstedt and Simon upon the weight
of this organ in young animals, it appears for a short time after birth to increase not
merely absolutely, but even faster than the rest of the system, and during the next
period only to keep pace with the increase of the body. After the second year it ceases
to grow, and becomes gradually converted by the eighth or twelfth year into a fatty
mass. In this condition the corpuscles of the thymus disappear, forming, according
to Simon's opinion, the nuclei of cells which become developed into the cells of adipose
tissue. At puberty the thymus is generally reduced to a mere vestige which has
entirely lost its original structure, and consists of brownish tissue occupying the
upper part of the anterior mediastinum. Occasionally it is still found in good condi-
tion at the twentieth year; but generally only traces of it remain at that time, and
these are rarely discoverable beyond the twenty-fifth or thirtieth year.
The thymus gland presents no difference in the two sexes. It exists, according to
Simon, in all animals breathing by lungs, and is persistent in those which hybernate,
though only as a mass of fat.
THE URINARY ORGANS.
THE urinary organs consist of the kidneys, the glandular organs by which
the urine is secreted, and of the ureters, bladder, and urethra, which are
the organs of its excretion and evacuation. As being locally connected, the
suprarenal capsules are usually described along with these organs, though
they have no relation, as far as is known, to the secretion of urine.
THE KIDNEYS.
The kidneys, two in number, are deeply seated in the lumbar region,
lying one on each side of the vertebral column, at the back part of the
abdominal cavity, and behind the peritoneum. They are situated on a level
with the last dorsal and the two or three upper lumbar vertebrae, the right
kidney, however, being placed a little lower down than the left, probably in
consequence of the vicinity of the large right lobe of the liver. They are
maintained in this position by their vessels, and also by a quantity of sur-
rounding loose areolar tissue, which, usually contains much dense fat (tunica
adiposa). The size of the kidneys varies in different instances. Ordinarily,
they measure about four inches iu length, two and a half inches in breadth,
and an inch and a quarter or more in thickness. The left kidney is usually
of a longer and thinner shape, whilst the right is shorter and wider.
Weight. — The average weight of the kidney is usually stated to be about 4^ oz. in
the male, and somewhat less in the female. According to Clendinning, the two kid-
neys of the male weigh on an average 9| oz., and those of the female 9 oz. The
estimate of Rayer is 4^ oz., for each organ in the male, and 3§ oz. in the other sex.
Reid's observations (made on sixty -five males and twenty-eight females, between the
ages of twenty -five and fifty -five) would indicate a higher average weight, viz., rather
more than 5^ oz. in the former, and not quite 5oz. in the latter, — the difference
between the two sexes being therefore upwards of half an ounce. The prevalent weights
of the kidney, as deduced from the tables of Reid, are, in the adult male (160
observations) from 4^ oz. to 6 oz., and in the adult female (74 observations) from
4 oz. to 5^ oz. The tables more recently published by Peacock give still higher
average results as to the weight of these organs. The two kidneys are seldom of
FORM AND TOSTTION OF THE KIDNEYS. 927
equal weight, the left being almost always heavier than the right. The difference,
according to Rayer, is equal to about one-sixth of an ounce. The actual average
difference was found by Reid in ninety-three cases (male and female), to be rather
more than one-fourth of an ounce. The proportionate weight of the two kidneys to
the body is about 1 to 240.
The specific gravity of the renal substance is, on an average, T052.
^
The surface of the kidney is smooth and has a deep red colour. Its form,
is peculiar : it is compressed before and behind, convex on its outer and
concave on its inner border, and somewhat enlarged at its upper and lower
ends.
The anterior surface, more convex than the posterior, is directed some-
what outwards, and is partially covered at its upper end by the peritoneum,
which is separated from it lower down by loose areolar tissue. The duo-
denum and ascending colon, both destitute of peritoneum behind, are in
contact with the anterior surface of the right kidney, and the descending
colon with that of the left. The front of the right kidney, moreover,
touches the under surface of the liver, and that of the left the lower ex-
tremity of the spleen. The posterior surface, natter than the anterior, and
imbedded in areolar tissue, rests partly upon the corresponding pillar of the
diaphragm, in front of the eleventh and twelfth ribs; partly on the anterior
layer of the lumbar fascia, covering the quadratus lumborum muscle ; and,
lastly, on the psoas muscle. The external border, convex in its general
outline, is directed outwards and backwards towards the wall of the abdo-
men. The internal border, concave and deeply excavated towards the
middle, is directed a little downwards and forwards. It presents in its
middle a longitudinal fissure bounded by an anterior and posterior lip, and
named the hilus of the kidney, at which the vessels, the excretory duct, and
the nerves enter or pass out. In this hilus, the renal vein lies in front, the
artery and its branches next, and the expanded excretory duct or ureter
behind and towards the lower part of the hilus. The upper end of the
kidney, which is larger than the lower, is thick and rounded, and supports
the suprarenal capsule, which descends a little way upon its anterior sur-
face. This end of the kidney reaches, on the left side, to about the upper
border of the eleventh rib, and, on the right, half a rib's breadth lower. It
is moreover directed slightly inwards, so that the upper ends of the two
kidneys are nearer to each other than the lower ends, which are smaller and
somewhat flattened, diverge slightly from the spine, and reach nearly as low
as the crest of the ilium. It may here be remarked that, by placing the
larger end of a kidney upwards and its flatter surface backwards, or by
noticing the relation of the parts in the hilus, the side of the body to which
the organ belongs may be determined.
Varieties, — The kidneys present varieties in form, position, absolute and relative
size, and number. Thus, they are sometimes found longer and narrower, and some-
times shorter and more rounded than usual. Occasionally one kidney is very small,
whilst the other is proportionately enlarged. The kidneys may, one or both, be
situated lower down than usual, even in the pelvis.
Instances are now and then met with in which only one kidney is present, the single
organ being sometimes, though not always, formed by the apparent junction of the
two kidneys across the front of the great blood-vessels and vertebral column. The
united organ has usually the form of a crescent, the concavitj of which is directed
upwards,— hence the appellation of the horse-shoe kidney. Sometimes two united
kidneys are situated on one or other side of the vertebral column, in the lumbar
region, or, but much more rarely, in the cavity of the pelvis. In other very rare cases,
928
THE KIDNEYS.
three distinct glandular masses have been found, the supernumerary organ being
placed either in front or on one side of the vertebral column, or in the pelvic cavity.
Structure. — The kidney is surrounded by a proper fibrous coat, which
forms a thin, smooth, but firm investment, closely covering the organ. It
consists of dense fibro-areolar tissue, together with numerous fine elastic
fibres, and can easily be torn off from the substance of the gland, to which
it adheres by minute processes of connective tissue and vessels.
On splitting open the kidney by a longitudinal section, from its outer to
its inner border, the fissure named the hilus is found to extend some dis-
tance into the interior of the organ, forming a cavity called the sinus of the
kidney, into the bottom of which the fibrous coat is prolonged. In such
a section, also, the commencement of the excretory duct and the disposition
of the substance of the organ are seen to the greatest advantage.
The ureter, or excretory duct of the gland, which is dilated at its upper
end as it approaches the hilus, is seen to expand within the sinus into a
funnel-shaped cavity, compressed from before backwards, named the pelvis of
the kidney. Within the sinus, partly concealed by the vessels, the pelvis
divides usually into three, or sometimes only two, principal tubes, which
subdivide into several smaller tubes named the calyces or infundibula.
These calyces, which vary in number from seven to thirteen or more, form
short funnel-shaped tubes, into each of which a papilla of the renal sub-
stance projects. A single calyx often surrounds two, sometimes even three
papillae, which are in that case united together : hence, the calyces are in
general not so numerous as the papillae. The spaces between the calyces are
occupied by a considerable amount of fat, imbedded in which are seen the
main branches of the renal vessels.
Fig. 649.
Fig. 649. — PLAN OF A LONGITUDINAL SEC-
TION THROUGH THE PELVIS AND SUBSTANCE
OF THE RIGHT KIDNEY. £
a, the cortical substance ; 5, 5, broad part
of two of the pyramids of Malpighi ; c, c,
the divisions of the pelvis named calyces, or
infundibula, laid open ; c', one of these un-
opened ; d, summit of the pyramids or pa-
pillae projecting into calyces ; e, e, section of
the narrow part of two pyramids near the
calyces ; p, pelvis or enlarged divisions of the
ureter within the kidney ; ut the ureter ; s,
the sinus ; h, the hilus.
Like the rest of the ureter, the
pelvis and greater part of the calyces
consist of three coats, viz., a strong
external fibro-areolar and elastic tunic,
which becomes continuous round the
bases of the papillae with that part of
the proper coat of the kidney which
is continued into the sinus ; secondly,
a thin internal mucous coat, which is reflected over the summit of each
papilla ; and thirdly, between these two, a double layer of muscular fibres,
longitudinal and circular. The longitudinal fibres are lost near the base of
the calyx, but the circular fibres, according to Henle, form a continuous
MEDULLARY AND CORTICAL SUBSTANCES. 929
circular muscle round the papilla where the wall of the calyx is attached
to it.
The substance of the kidney consists of two parts, the medullary and
cortical, differing in colour, consistence, and structure.
The internal or medullary substance does not form a continuous struc-
ture, but is collected into a series of conical masses called the pyramids of
Malpighi, the bases of which, directed towards the surface of the kidney,
are imbedded in the cortical substance, whilst their apices are turned to-
wards the sinu.*, and, projecting into the calyces, form the papillm already
mentioned. There are generally more than twelve pyramids, but their
number is inconstant, varying from eight to eighteen. The medullary
portion of the kidney is more dense than the cortical, and is distinctly
striated, owing to its consisting of small diverging uriniferous tubes, and to
its blood-vessels being arranged in a similar manner. Towards the papillae
the pyramids are of lighter colour than the cortical substance, but at their
base they are usually purplish and darker.
The external or cortical substance is situated immediately within the
fibrous capsule, and forms the superficial part of the organ throughout its
whole extent to the depth of about two lines, and moreover sends prolonga-
tions inwards (septula renum, or columns Bertini) between the pyramids.
It is of a nearly uniform light crimson brown appearance, and is soft and
easily lacerated in directions vertical to the surface. When so lacerated,
its torn surface exhibits a columnar appearance, coarser than that of torn
medullary substance, and more rough and irregular ; the columnar appear-
ance arising from the alternation of groups of straight and convoluted
tubules, and the roughness being caused by the convoluted tubules and the
interspersion of small round bodies of a deeper colour, the Malpighian
corpuscles. The groups of straight tubules in the cortical substance are con-
tinued from those of the medullary substance, and are surrounded by tha
convoluted tubes into which they pass, not only on their sides but likewise
at their outer extremities, so that no straight tubules reach the surface
of the organ : they are termed pyramids of Ferrein. The Malpighian cor-
puscles are imbedded among the convoluted tubes, and appear disposed in
double rows between the pyramids of Ferrein, and likewise more superficially,
but nowhere reach quite to the surface.
The pyramidal masses found in the adult kidney indicate the original sepa-
ration of this gland into lobules in the earlier stages of its growth (fig. GG1).
Each of these primitive lobules is in fact a pyramid surrounded by a proper
investment of cortical substance, and is analogous to one of the lobules of
the divided kidneys, seen in many of the lower animals. As the human
kidney continues to be developed, the adjacent surfaces of the lobules
coalesce and the gland becomes a single mass, and the contiguous parts of
the originally separate cortical investments, being blended together, form
the partitions between the pyramids already described. Moreover, upon
the surface of the kidney even in the adult, after the removal of the fibrous
capsule, faintly marked furrows may be traced on the cortical substance,
opposite the intervals in the interior between the several papillie with their
calyces ; and not unfrequently instances occur in which a deeper separation
of the original lobules by grooves remains apparent in the adult kidney.
Tubuli uriniferi. — On examining the summit of one of the papillae care-
fully, especially with the aid of a lens, a number of small orifices may be
seen, varying in diameter from 3-^0 tn to 20 otn of an inch > they are fre"
quently collected in large numbers at the bottom of a slight depression or
930 THE KIDNEYS.
foveola found near the summit of the papilla, but most commonly the
surface is pitted over with about a score of minute depressions of this sort.
On tracing these minute openings into the substance of the pyramids, they
are discovered to be the mouths of small tubes or ducts, called the urini-
ferous tubes (tubuli uriniferi), which thus open upon the surface of the
several papillae into the interior of the calyces.
As these tubuli pass up into the pyramidal substance, they bifurcate again
and again at very acute angles, their successive branches running close to-
gether in straight and slightly diverging lines, and continuing thus to
divide and subdivide until they reach the sides and bases of the pyramids,
whence they pass, greatly augmented in number, into the cortical sub-
stance, where they enter the pyramids of Ferrein. These straight tubules
continued up from the orifices in the papillae are sometimes called ducts of
Bellini : they are largest near their orifices, at a short distance from which,
within the papillae, their diameter varies, according to Huschke, from ^th
to ^th of an inch. Further on in the pyramid they become smaller,
measuring about ^th of an inch in diameter, and then do not diminish as
they continue to bifurcate, but remain nearly of the same uniform average
diameter.
The convoluted tubes, tubuli contorti, which form the greater part of the
cortical substance, and, together with vessels and connecting stroma, the
whole of its outermost portion, vary considerably in diameter, but they
maintain commonly the same average width as the straight tubes, namely
g^th of an inch. The epithelium in the convoluted tubules may be termed
cubical ; it does not present any marked contrasts in thickness, but in some
of the smaller tubules it is clear, while in the majority it is turbid, and
with its cells ill-defined.
Besides these tubes, long well-known to anatomists, attention has more
recently been called by Henle to the presence in the Malpighian pyramids
of a number of tubes, which may be roughly estimated as having only a
third or a fourth of the diameter of the others, and which, after descending
between the larger tubes a variable distance towards the papillae, then
turn abruptly and reascend. The tubes in question have been designated
looped tubes of Henle. According to this author, the small differ from the
large tubes not only in size but in the greater thickness of their walls. By
the action of dilute hydrochloric acid, the epithelium of the large tubes is
destroyed and that of the looped tubes brought into view. The epithelium
of the looped tubes, Henle also states, is clear and squamous towards the
papillae, but towards the bases of the pyramids it becomes turbid, like that
of the convoluted tubules.
Chrzonszczewsky, while he both figures and describes looped uriniferous tubes,
considers that the merit of having discovered them rests with Ferrein, and that those
described by Henle as having squamous epithelium are really blood-vessels. Although,
however, it is admitted that loops are formed by blood-vessels very similar to the
looped tubes of Henle, it must be regarded as certain that loops of the uriniferous
tubules are much more numerous than Chrzonszczewsky is willing to admit, and for
a knowledge of them as constant and regularly disposed elements of the renal struc-
ture science is indebted to Henle.
Imbedded among the convoluted tubules are the Malpighian corpuscles,
the structure and connections of which must be taken into consideration,
before the disputed course of the uriniferous tubes can be discussed.
The Malpighian corpuscles are small bodies of a rounded or slightly ob-
long shape, which have an average diameter of ^th of an inch, but
URIXIFEROUS TUBES AND MALPIGHIAN CORPUSCLES.
931
sometimes of only „-— 0 tli or 77-0th of an inch. They consist each of a mem-
branous capsule, containing a tuft of blood-vessels. The vascular tuft or
Fig. 650. — DIAGRAMMATIC RE- pjg^ Q%Q
PRESENTATION OF A PART OP
THE STRAIGHT AND CONVO-
LUTED URINIFEROUS TUBFS
WITH THE GLOMERULT (from
Frey after a drawing by
Miiller).
6, by two large straight tuhes
in the medullary substance of the
pyramid; c, convoluted tubes
with several of their termina-
tions in the Malpighian cap-
sules as iu d ; a, three arteries
passing up the pyramid and
dividing into branches to the
glomeruli : the efferent vessels
are also represented and the
network of capillaries between
them and the veins.
glomerulus is formed by a
small afferent artery break-
ing up at once into a num-
ber of minute branches,
which possess simple nu-
cleated walls, form convo-
luted loops, and are re-
united in a single efferent
vessel, placed close to the
afferent : the further his-
tory of the afferent anl
efferent vessels will be de-
scribed later. The capsule,
by which the glomerulus is
surrounded, is formed of
homogeneous membrane.
The capsule receives the
two vessels at one part ;
and at another it is con-
tinued into a convoluted
uriniferous tubule, as was
first pointed out by Bow-
man. Gerlach and others
have considered that it
may be formed on one side ;
or may be so placed at the
extreme point of a looped
tubule, that it appears to
be continuous with two
tubuli ; but it is now gene-
rally admitted, as the result
of filling the tubes both by injections from the ureter and by extravasation
from the glomeruli, that, although in certain amphibia they may be placed
8P 2
932
THE KIDNEYS.
laterally, in mammals they are always terminal, communicating with one
tubule only. The interior of the capsule is lined by a transparent delicate
squamous epithelium ; but there is still much difference of opinion as to the
exact relation of the glomerulus to the epithelium within the capsule. Bow-
man has described the glomerulus as hanging naked in the interior of the
capsule, and presenting thus the greatest possible facility for the filtration
of water from its vessels into the tubule : a view which has been supported by
Ecker, Henle, and others. Kolliker, on the other hand, has observed epithe-
lium on the free extremity of the glomerulus, looking towards the com-
mencing tubule, while at the sides he can find only a single layer, which ho
Fig. 651.
Fig. 652.
Fig. 651.— THREE MALPIGHIAN CAPSULES IN CONNECTION WITH THE BLOOD-VESSELS
AND URINIFEROUS TUBES OP THE HUMAN KIDNEY (from Kolliker after Bowman). *T5
a, termination of an interlobular artery ; b, afferent arteries ; c, a denuded vascular
glomerulus ; d, efferent vessel ; e, two of the glomeruli enclosed by the Malpighian
capsules ; /, uriniferous tubes connected with them.
Fig. 652.— SEMIDIAQRAMMATIC REPRESENTATION OF A MALPIGHIAN BODY IN ITS
RELATION TO THE URINIFEROUS TUBE (from Kolliker). ~Q
a, capsule of the Malpighian body continuous with 6, the membrana propria of the
coiled uriniferous tube ; c, epithelium of the Malpighian body ; d, epithelium of the
uriniferous tube ; c, detached epithelium ; /, afferent vessel ; g, efferent vessel ; h,
convoluted vessels of the glomerulus.
represents as adherent on one side to the glomerulus, and on the other to the
capsular wall. Lastly, Isaacs, Moleschott, and Chrzonszczewsky maintain that
the glomerulus and the capsule have each a separate coating of epithelium,
and they agree in stating that the cells of the layer covering the glomerulus
are considerably larger than those lining the capsule : Chrzonszczewsky re-
commends sections of frozen kidneys as showing very perfectly the two layers
in situ.
THE UBIXIFEEOUS TUBES.
933
Origin, course, and connections of the uriniferous tubules. — When the
tubuli uriniferi are followed in their apparent course, the straight tubes are
Fig. 653.— PORTION OP THE URINIFEROUS TUBES, Fig. 6 3.
MAGNIFIED (from Baly).
A, portion of a convoluted tube from the cortical sub-
stance ; B, epithelial cells from the interior of the tube,
magnified 700 diameters.
easily traceable from the Malpighian pyramids
into the pyramids of Ferrein, and from these
into the tubuli contorti. Thus, after the obser-
vations of Bowman bad demonstrated the con-
nection of the Malpighian corpuscles with the
tubuli contorti, it appeared natural to believe
that the tubuli contorti at one extremity com-
menced in capsules of Malpighian corpuscles,
and at the other were continued into straight
tubules, which opened at the summits of the
papillse. It appears, however, from the con-
current testimony of recent writers, that con-
siderable complexity of arrangement intervenes between the terminations of
the straight tubes and the commencements of the tubuli contorti, with
which the Malpighian corpuscles are connected.
It may be considered as certain from the researches of Ludwig and
Fig. 654.
Fig. 654.— TRANSVERSE SEC-
TION OF A RENAL PAPILLA
(from Kolliker). ^
a, larger tubes or papillary
ducts ; 6, smaller tubes of
Henle ; c, blood-vessels, dis-
tinguished by their flatter epi-
thelium ; d, nuclei of the
stroma.
Zawarykin conducted by
means of injections, and
from those of Schweigger-
Seidel by means of isola-
tion of the tubules ia small
animals, that the tubuli
contorti which commence
ia the Malpighian cor-
puscles are continued into
the looped tubes of Henle,
and that these open into the straight tubules or ducts of Bellini, either
directly or through the intervention of convoluted tubes of junction of
larger size, said by Schweigger-Seidel to be always present. According
to Henle, the straight tubules turn rather sharply round near the surface of
the kidney, and again course inwards ; and this appearance, which has been
corroborated by other observers, he believes to result from anastomoses of
the tubules in arches, two and two. It must be regarded as a question still
934
THE KIDXEYS.
open to discussion whether all the smaller tubules which open into these
arches belong to the convoluted and looped tubules already described, as is
believed by the greater number of recent observers, or whether there is not
likewise, as is held by Heule and Chrzonszczewsky, a set of small anasto-
mosing tubules, some of which may have blind extremities.
Fig. 655. Fig. 655. — DIAGRAM OP THE LOOPED
URINIFEROUS TUBES AND THEIR
CONNECTION WITH THE CAPSULES OF
THE GLOMERULI (from Southey after
Ludwig).
In the lower part of the figure one
of the larger branching tubes is shown
opening on a papilla ; in the middle
part three of the looped small tubes
are seen descending to form their
loops, and reascending in the medul-
lary substance ; while in the upper
or cortical part two of these tubes,
after some enlargement, are repre-
sented as becoming convoluted and
dilated in the capsules of glomeruli.
According to Schweigger-
Seidel the limbs of the looped
tubes are always of unequal size,
that which is continued into tho
intermediate tubes being tho
larger of the two ; and he divides
the loops into two sorts, one in
which the narrowest portion
forms the loop, and another in
which, at the loop, the tube is
of the diameter of the larger of
its two limbs. He likewise
points out the existence of occa-
sional capsular dilatations, where
the looped tubes meet the inter-
mediate portions, which, as he
remarks, may explain the state-
ment of Moleschott, that he had
found in mammals capsules com-
municating with two tubules.
The investigations of Chrzon-
szczewsky deserve special men-
tion, on account of the novel
method to which he resorted for
the verification of his views, and
which promises to throw much
light on some of the physiological processes as well as on the minute struc-
ture of animals. This method consists in the introduction of the colouring
matter with which the observed vessels are to be filled into the system of a
living animal, either by direct infusion into the blood, or along with food
int) the alimentary canal, or by absorption from any of the larger serous
cavities. The results of this mode of colouring the vessels and ducts
ORIGIN AND COURSE OF THE TUBES.
935
have already been noticed in its application to the liver. For the kidney
Chrzonszczewsky made use of the carminate of ammonia, which is freely
eliminated with the urine. In order to obtain a full colouring of the
blood-vessels, first the renal veins, and afterwards the arteries, are tied
soon after a certain portion of the coloured fluid has been introduced
into the jugular vein of the living animal. To obtain a coloured injection
of the uriniferous tubes, the animal is allowed to live for about an hour
after the introduction of the carmine liquid, and then the ureters are
tied, while the renal blood-vessels are carefully washed out with a weak
solution of common salt ; and, to preserve the specimens from after infiltra-
tion of the colour, they are immersed in absolute alcohol acidulated with
glacial acetic acid.
Fig. 657.
Fig. 656.
Fig. 656. — TRANSVERSE SECTION OF THE MEDULLARY SUBSTANCE OF THE PIG'S
KIDNEY (from Chrzonszczewsky). —•
The drawing represents a small portion of the kidney of an animal into which colouring
matter had been infused during life so as to fill the blood-vessels, by which means the
distinction between them and the uriniferous tubes both larger and smaller is established,
as well as by the different character of the lining epithelium ; the section is made near the
papilla; TB, the larger uriniferous tubes or tubes of Bellini ; TF, the smaller uriniferous
tubes or looped tubes of Henle, named by Chrzonszczewsky tubes of Ferrein ; VR, the
vasa recta or larger blood-vessels; c, the small vessels and capillaries; s, the stroma.
Fig. 657. — LARGER AND SMALLER URINIFEROUS TUBES FROM THE MEDULLARY
SUBSTANCE OF THE PIG'S KIDNEY (from Chrzonszczewsky).
1, 1, two of the larger tubes, connected by a transverse tube at 2, and presenting a
looped arrangement at 3 ; from this place two smaller uriniferous tubes, 4, 4, are seen
taking their origin, as well as at the other places, 5, 5.
Blood-vessels. — The kidneys are highly vascular, and receive their blood
from the right and left renal arteries (p. 414), which are very large in pro-
portion to the size of the organs they supply. Each renal artery divides
into four or five branches, which, passing in at the hilus, between the vein
936
THE KIDNEYS.
Fig. 658.
and ureter, may be traced into the sinus of the kidney, where they lie
amongst the infundibula, together with which they are usually imbedded
in a quantity of fat. Penetrating the sub-
stance of the organ between the papilla?, the
arterial branches enter the cortical substance
found in the intervals between the medullary
cones, and go on, accompanied by a sheathing
of areolar tissue derived from the proper
coat, and dividing and subdividing, to reach
the bases of the pyramids, where they form
arches between the cortical and medullary
parts, which however are not complete, and
in this respect differ from the freely anasto-
mosing venous arches which accompany
them. From the arches smaller interlobular
Fig. 658. — INJECTED GLOMERULUS FROM THE INNER
PART OP THE CORTICAL SUBSTANCE OF THE HORSE'S
KIDNEY (from Kolliker after Bowman). \°.
a, interlobular artery ; a/, afferent artery ; ra m,
convoluted vessels of the glomerulus ; ef, efferent or
straight arteriole ; b, its subdivision in the medul-
lary substance.
arteries are given off, which pass outwards
between the double layers of Malpighian cap-
sules which intervene between the pyramids
of Ferrein ; and from these interlobular arteries
are derived the afferent arteries of the glo-
meruli. The renal arteries give branches
likewise to the capsule of the kidney which
anastomose with branches of the lumbar ar-
teries, and that so freely that Ludwig was able
partially to inject the kidneys of a dog from the aorta after the renal arte-
ries had been tied. (See also Turner as cited at p. 417.) Within the
glomerulus the afferent artery breaks up into convoluted branches of very
small size, which are gathered together again to form the efferent vessel.
The efferent vessel is so far comparable with the vena porta3 of the liver
that it breaks up again into capillaries, which form a close honeycomb net-
work surrounding the convoluted tubules, and a less copious network with
elongated meshes round the straight tubes of the cortical substance. Within
the medullary substance are found numbers of straight vessels, vasa recta,
which lie between the uriuiferous tubes, and at the bases of the Malpighian
pyramids are arranged in bundles extending inwards from between tha
pyramids of Ferrein. These vessels partly break up into capillaries, from
which returning veins arise, and partly, as has been already noticed,
form loops similar to those of the looped tubules of Henle. The mode
in which the va?a recta take origin has been made the subject of con-
Fiderable discussion. According to Bowman, Kolliker, and Ludwig and
Zawarykin, the vasa efferentia from the innermost glomeruli are larger
than the others, and break into brushes of these vasa recta. Arnold,
Virchow, Beale, and others maintain the direct origin of vasa recta from
the renal arteries without intervention of the glomeruli. Huschke, Henle,
MINUTE DISTRIBUTION OF RENAL BLOOD-VESSELS.
937
and Hyrtl consider that they take origin in the capillary network of the
zone at the base of the pyramids (" neutral zone ").
Fig. 659.
Fig. 659.— DIAGRAM SHOWING THE RELATION OP THE
MALPIGHIAN BODY TO THE URINIFEROCS DUCTS AND
BLCOD-VESSELS (after Bowman).
«, one of the interlobular arteries ; a', afferent artery
passing into the glomerulus ; in, vascular tuft formed
•within the glomerulus ; c, capsule of the Malpighiau
body, forming the termination of and continuous with t,
the uriniferous tube ; e', e' , efferent vessels which sub-
divide in the plexus p, surrounding the tube, and finally
terminate in the branch of the renal vein e.
Small veins, arising by numerous venous
radicles from the capillary network of the kid-
ney, are seen near the surface of the gland,
arranged so as to leave between them minute
spaces, which appear nearly to correspond with
the bases of the so-called pyramids of Ferrein. These vessels, some of
which have a stellate arrangement (stellular., Verheyen), joined by numerous
branches from the fibrous coat of the kidney, end in larger veins, which again
Fig. 660.
Fig. 660. — LONGITU-
DINAL SECTION OP A
PART OF THE TUBU-
LAR SUBSTANCE AND
THE ADJACENT CoR-
TICAL SUBSTANCE OF
THE KIDNEY (from
Southey).
The blood-vessels
have been minutely in-
jected, and the figure
is designed principally
to show the origin of
the vasa recta. A A,
ascending arteries di-
vided longitudinally ;
G V, cortical veins ;
A a, transverse section
of anastomotic arch ;
?n, Malpighian bodies ;
R, vasa recta ; M V,
medullary veins.
unite into arches
round the bases of
the pyramids of
Malpighi. Here
they receive the
veins of the pyra-
mids, which com-
mence in a beauti-
ful plexus round the orifices of the tubuli on the surface of the papillae.
Venous trunks then proceed, in company with the arteries, through the
cortical envelope between the pyramids, to the sinus of the kidney.
Joining together, they escape from the hilus, and ultimately form a single
938 THE KIDNEYS.
vein, which lies in front of the artery, and ends in the inferior vena cava
(p. 474).
Nerves. — The nerves which have been traced into the kidneys are small.
They come immediately from the renal plexus and the lesser splanchnic
nerve, and contain filaments derived from both the sympathetic and cerebro-
spinal systems. They may be traced accompanying the arteries to their finer
branches, but it is uncertain how they end.
Intertubular Stroma. — Between the tubules and vessels of the kidney,
although they are disposed closely together, a certain very small amount of
interstitial matrix exists, first described by Goodsir, then by Bowman and
others, and to which attention has latterly been paid by a number of
observers, and especially by Beer. This matrix is for the most part nearly
homogeneous, but has a more fibrous character in the vicinity of the rami-
fications of the blood-vessels. Fibres are likewise described by Ludwig and
Zawarykin as passing round the Malpighian corpuscles, and others have
been seen by Henle, coiling round the tubes of the medullary substance.
The stroma is more abundant in the cortical substance than in the greater
part of the medullary ; but according to Henle it is very abundant towards
the apices of the papillae. Nuclei and connective tissue corpuscles are scat-
tered through its substance. It is much more abundant in animals than in
man, and in the human kidney it is more apparent in the young than in the
adult, and is also much richer in corpuscles ; in this respect resembling the
connective tissue generally.
Absorbents. — The lymphatics of the kidney are numerous, consisting of a
superficial set, and of deep lymphatics which issue from the hilus with the
blood-vessels. According to the researches of Ludwig and Zawarykin, the
stroma of the kidney forms a thick network of freely intercommunicating
lymphatic spaces, guided to the surface along the tissue round the blood-
vessels. These spaces are similar to those previously found by Ludwig and
Tomsa in the testicle, and held by His to possess epithelial walls. They are
most abundant in the cortical substance.
Among writings on the kidney, the following may be here referred to : — Bowman, in
Philos. Trans. 1842; Toynbee, in Medico-Chir. Trans. 1846; Gerlach, in Muller's
Archiv, 1845; Johnson, article Ren, in Clyclopsedia of Anat. and Phys. ; Isaacs, in
Trans. New York Acad. of Medicine, vol. i., 1857 ; Henle, Zur Anatomic der Niere,
Gottingen, 1862, and in Handbuch; Ludwig and Zawarykin, in Wiener Kais, Acad.
Sitzungsbericht, vol. xlviii. 1864; Chrzonszczewsky, in Virchow's Archiv, xxxi. 1864;
Schweigger-Seidel, Die Niere des Menschen und der Saiigethiere. Halle, 1865 ; Southey,
in St. Bartholomew's Hosp. Reports, 1865; also, on the stroma, Goodsir, in Lond. and
Edin. Journ. of Med. Science, May, 1842 ; and Beer, Die Bindesubstanz d. Menschlichen
Niere, Berlin, 1859.
Development. — The development of the kidneys, and also that of the suprarenal cap-
sules will be described later with that of the genito-urinary organs.
The Urine. — This is a complex and somewhat variable fluid, containing in
solution animal substances characterised by having a large amount of nitrogen in
their composition, and derived, it would seem, from the waste of the tissues ; also
saline substances, and adventitious matters which have been introduced into the
blood. The average quantity secreted daily is from 30 to 40 fluid ounces. Its specific
gravity varies in health from 1-015 to T030, the average standard being T020. It is
slightly acid in its reaction, and contains some mucus and epithelium. A thousand
parts of ordinary urine usually contain 933 parts of water, and 67 of solid matter.
The researches of Bowman upon the structure of the kidney in man and animals,
render it probable that the solid urinary constituents are secreted by the tubuli, and
that the watery part of the urine simply transudes through the vessels of the glomeruli.
The following analysis of the solid contents of the urine is from Lehmann, but it
THE URIXE THE SUPRARENAL BODIES. 939
must be considered approximative only, since the proportion of the ingredients is
liable to great variation in dependence upon food, exercise, and other conditions : —
Urea ........ 49'68
Uric acid ........ 1-61
Extractive matters, ammoniacal salts, and chloride of sodium . 28 '9 5
Alkaline sulphates . ...... 11-58
Alkaline phosphates . . . . . . 5-96
Phosphates of lime and magnesia . . . 1-50
99-28
Among the extractive matters are kreatine, kreatinine, and hippuric acid.
SUPRARENAL BODIES.
The suprarenal bodies or 'capsules, or suprarenal glands, (capsulae atrabi-
larise sen renes suecenturiati of old anatomists), are two flattened bodies,
each of which has a somewhat crescentic or bent triangular shape, and sur-
mounts the corresponding kidney. The upper border, convex and thin, is
often considerably elevated in the middle so as to form two sides of a tri-
angle. The lower border is concave, and rests upon the anterior and inner
part of the summit of the kidney, to which it is connected by loose areolar
tissue : it is thick, and almost always deeply grooved. The posterior sur-
face rests upon the diaphragm. Its anterior surface is covered on the right
side by the liver, and on the left by the pancreas and spleen : it presents an
irregular fissure named the hilus, from which the suprarenal vein emerges.
The right capsule, like the right kidney, is placed lower down than the left.
The suprarenal capsules vary in size in different individuals, and the left is
usually somewhat narrower at its base, but longer from above downwards,
and larger than the right. They measure from an inch and a quarter
to an inch and three-quarters in height, and about an inch and a quarter in
width ; their thickness is from two to three lines. The weight of each in the
adult is from one to two drachms.
Besides a covering of areolar tissue mixed frequently with much fat, the
suprarenal capsules have a thin fibrous investment. Externally, they have
a yellowish or brownish-yellow colour. When divided, they are seen to
consist of two substances : one, external or cortical, is of a deep yellow
colour, firm and striated, and forms the principal mass of the organ ; the
other, internal or medullary, is in the adult of a dark brownish-black hue,
and so soft and pulpy that some anatomists have erroneously described a
cavity within it.
The fibrous investment is so intimately connected with the deeper parts
that it cannot be removed without lacerating the subjacent structure. Its
deeper layers are destitute of elastic fibres, and are particularly rich in
nuclei : they are continuous with the septa which enter into the formation
of the substance of the organ.
The cortical part of the suprarenal body, examined with a low magni-
fying power, is seen to consist of stroma, in which are imbedded columnar
and reticulated masses measuring on an average ^th of an inch in
diameter, arranged vertically to the surface of the organ, and containing
cellular constituents. In the deepest part of the cortex, however, the
colour is darker, and the columnar arrangement is lost, the stroma being
more equally scattered ; and immediately beneath the fibrous coat there is
another very narrow layer in which the stroma forms oval spaces, of which
it is difficult to say whether they communicate with the extremities of the
columns or not. These inner and outer layers have been named by J. Arnold
respectively zona reticularis and zona glomerulosa, while he applies the term
940
THE SUPRARENAL BODIES.
zona fasciculata to the main part ; but as the transition from one of these
parts to another is not sudden nor indicated by any line of demarcation, they
Fig. 661.
Fig. 662.
Fig. 661. — FRONT VIEW OP THE RIGHT KIDNEY AND SUPRARENAL BODY OP A FULL
GROWN FCETUS.
This figure shows the lobulated form of the foetal kidney r ; v, the renal artery and
vein ; u, the ureter ; s, the suprarenal capsule, the letter is placed near the sulcus in
which the large veins (v') are seen dividing aud dipping into the interior of the organ.
Fig. 662. — SECTIONS OP THE SUPRARENAL BODY.
A, vertical section of the suprarenal body of a foetus twice the natural size, showing
the lower notch by which it rests on the summit of the kidney, and the anterior notch by
which the veins penetrate, together with the distinction between the medullary and
cortical substance, f
B, longitudinal section of the cortical substance, showing the capsules containing
nucleated cells and intervening blood-vessels. 2-~ The figure represents a small fragment
of a section made perpendicularly to the surface in a suprarenal body of which the
bloodvessels were partially injected, a, one of the superficial masses of cells (in the zona
glomerulosa of J. Arnold) ; a', one of the longer masses slightly deeper (zona fasciculata) ;
6, bloodvessels running in the septa of connective tissue between the cell-masses in a
part of the specimen ; c, connective tissue and sheath substance on the surface ; c' , con-
nective tissue of the septa : this figure, though true to nature in the representation of the
several textures, is so far diagrammatic that the space occupied by the shorter masses of
cells towards the surface is proportionally too small.
are probably only modifications of the same structure. The contents of the
stroma consist of nucleus-like bodies from j^^th to f^th of an iuch in
diamettr, mixed with minute yellowish granules, aud. oily particles with
granular matter adhering to them, together with large groups of closely set
nucleated cells containing granular matter and oily molecules. The cells
vary from ^-()th to ~5-^th of an inch in size, and their opposing sides are
somewhat flattened, giving them the form of irregular polyhedra : the larger
cells are most loaded with oil-globules. In many instances, probably, the
appearance of free nuclei and oil-globules is to be explained by cell-walls
being ruptured or remaining unrecognised.
MINUTE STRUCTURE OF SUPRARENAL BODIES. 941
According to Simon, the columns consist of distinct tubes with a limiting
membrane ; Ecker and others affirm that no continuous tubular cavities
exist, but that rows of closed vesicles, many of them oval in shape, and
overlapping each other, are placed in such manner as to resemble tubes ;
while Gray believes that the walls of adjoining vesicles are sometimes re-
moved by absorption, so that tubular cavities are formed by the coalescence
of neighbouring vesicles. Kolliker, however, and other observers, maintain,
with more correctness, that the so-called vesicles are merely loculi or cavities
in the stroma of the organ, possessing no distinct limitary membrane, and
producing the appearance of a tubular structure by their apposition in linear
series. The small arteries, entering from the surface, run parallel to these
columns, frequently anastomose together between them, and surround each
row of vesicles with a fine capillary network. Small bundles of nerves
pass inwards in the septa between the columns to reach the medullary part
of the organ, and their fibres begin to spread out in the zona reticularis,
but do not appear to be distributed to the cortical substance.
The medullary part of the suprarenal capsule is separated from the cortical
part by a layer of connective tissue, the fibres of which are parallel to the
two parts, and allow them to be easily separated one from the other in
sections prepared for the microscope. In the thinner parts of the adult
organ there is no medullary part, or it has shrunk away, and the layer of
connective tissue referred to is found separating the deep surfaces of two
opposed portions of the cortical part ; but in the young state the dis-
tinction of cortical and medullary probably extends throughout the whole.
The medullary part is traversed in the centre by venous trunks, which
receive the whole of the blood which has passed through the organ. The
stroma is delicate, arranged in a reticular manner; the pulpy substance which
lies in it is difficult of examination, but consists of cells, differing from those
of the cortex in being destitute of oil globules, and some of them branched.
The bundles of nerves which pass through the cortical substance run
between it and the medullary substance, and then form a copious interlace-
ment which extends through the whole of the medullary stroma. According
to Leidig and Luschka, the cells of the medullary substance are ganglionic ;
and Luschka states that he has found them both connected one with another
and with nerve-fibres ; but this view still requires confirmation. Moers,
while he denies that the cells of the medullary parenchyma are nervous,
describes ganglia on the nerves where their bundles begin to break up.
The medullary substance receives its blood by the continuation inwards
of the capillary network of the cortex, the blood from which is collected by
venous radicles which open into the stems in the centre of the organ.
Vessels. — The suprarenal bodies receive arteries from three sources, viz., from the
aorta, the phrenic, and the renal arteries. The distribution of their capillary vessels
has already been mentioned.
The veins, which pass out from the centre, are usually united into one for each
organ. The right vein enters the vena cava inferior immediately, whilst the left, after
a longer course, terminates in the left renal vein.
The lymphatics are imperfectly known. Kolliker has seen a few small trunks upon the
surface ; and Luschka has, in addition, observed others emerging from the interior in
company with the vein.
Nerves. — The nerves are exceedingly numerous. They are derived from the solar
plexus of the sympathetic, and from the renal plexuses. According to Bergmann,
some filaments come from the phrenic and pneumogastric nerves. They are made up
mainly of dark-bordered white fibres, of different sizes, and they have many small
942 THE URETERS.
ganglia upon them before entering the organ. The nerves are especially numerous in
the lower half, and inner border.
Accessory suprarenal capsules are occasionally met with, attached by connective
tissue to the main bodies; and varying from a small size up to that of a pea.
According to Duckworth, they possess no medullary part.
On the subject of the suprarenal capsules may be consulted, — Ecker, Der feinere Bau
der Nebennieren, Braunschweig, 1846 ; Simon on the Thymus Gland; Frey, article
" Suprarenal Capsules," in Cyclop, of Anat. and Phys. ; Harley, in the Lancet, June,
1858; Duckworth, in St. Bartholomew's Hosp. Reports, 1865; Moers, in Virchow's
Archiv, 1864, vol. xxix. p. 336 ; J. Arnold, Virchow's Archiv, 1866, vol. xxxv. p. 64 ;
Leidig, Kolliker, Luschka, and Henle, in their Handbooks.
Function. — Kothing is known positively with regard to the functions of the supra-
renal capsules. The opinion which has met with most acceptance among physiologists
is that these bodies belong to the class of blood-vascular glands, and exert some influence
upon the elaboration or disintegration of nutritive material. Bergmann, however, who
was the first to point out the richness of their nervous supply, suggested that they
were parts of the sympathetic nervous system, and in this opinion he has been followed
by Leidig and Luschka ; while Kolliker states that, upon anatomical grounds, he is
inclined to consider the cortical and medullary portions as functionally different ; the
former belonging to the group of vascular or ductless glands, the latter appearing to
be an apparatus appertaining to the nervous system. Brown-S6quard found that
injuries to the spinal cord in its dorsal region produced congestion and subsequent
hypertrophy of the suprarenal bodies. Addison has shown that a bronzed tint of
skin, together with progressive emaciation and loss of strength, is to be found in con-
junction with various forms of disease more or less involving and altering the structure
of these bodies.
THE URETERS.
The ureters are two tubes which conduct the urine from the kidneys into
the bladder. The upper, dilated, funnel-shaped commencement of each in
the pelvis of the kidney, into which the calyces pour their contents, has
already been described. Towards the lower part of the hilus of the kidney
the pelvis becomes gradually contracted, and opposite the lower end of the
gland, assuming the cylindrical form, receives the name of ureter. These tubes
extend downwards to the posterior and under part or base of the bladder,
into which they open, after passing obliquely through its coats.
The ureters measure from fourteen to sixteen inches in length, and their
ordinary width, is about that of a goose- quill. They are frequently, how-
ever, dilated at intervals, especially near their lower end. The narrowest
part of the tube, excepting its orifice, is that contained in the walla of the
bladder.
Each ureter passes, at first, obliquely downwards and inwards, to enter
the cavity of the true pelvis, and then curves forwards, and inwards, to
reach the side and base of the bladder. In its whole course, it lies close
behind the peritoneum, and is connected to neighbouring parts by loose
areolar tissue. Superiorly, it rests upon the psoas muscle, and is crossed,
very obliquely from within outwards, below the middle of the psoas, by the
spermatic vessels, which descend in front of it. The right ureter is close to
the inferior vena cava. Lower down, the ureter passes over the common
iliac, or the external iliac vessels, behind the termination of the ileum on
the right side and the sigmoid flexure of the colon on the left. Descending
into the pelvis, it enters the fold of peritoneum forming the corresponding
posterior false ligament of the bladder, and, reaching the side of the bladder
near the base, runs downwards and forwards in contact with, it, below the
obliterated hypogastric artery, and is crossed upon its inner side, in the male,
STRUCTURE OF THE URETERS.
943
by the vas deferens, which passes down between the ureter and the bladder.
In the female, the ureters run along the sides of the cervix uteri and upper
part of the vagina before reaching the bladder.
Having reached the base of the bladder, about two inches apart from one
another, the ureters enter its coats, and running obliquely through them for
about three-quarters of an inch, open at length upon the inner surface by
two narrow and oblique slit-like openings, which are situated, in the male,
about an inch and a half behind the prostate, and about the same distance
from each other. This oblique passage of the ureter through the vesical
walls, while allowing the urine to flow into the bladder, has the effect of
preventing its return up the ureter towards the kidney.
Structure. — The walls of the ureter are pinkish or bluish white in colour.
They consist externally of a dense, firm, areolar, and elastic coat, which in
quadrupeds decidedly contracts when artificially irritated. According to
Huschke, it possesses two layers of longitudinal fibres : Henle finds only an
inner longitudinal and an outer circular layer ; while Kolliker, who formerly
described the circular and outer longitudinal layers as the only layers
found except in immediate proximity to the bladder, now admits the inner
longitudinal and circular as the prin-
cipal layers, on Henle's authority, and Fig. 663.
states that the longitudinal fibres external
to the circular layer are absent at the
upper part of the tube.
Fig. 663. — EPITHELIUM FROM THE PELVIS OP
THE HUMAN KIDNEY (from Kolliker). ^p
A, different kinds of epithelial cells separated ;
B, the same in situ.
Internally, the ureter is lined by a thin
and smooth mucous membrane, which
presents a few longitudinal folds when
the ureter is laid open. It is prolonged
above upon the papillaa of the kidney,
and below becomes continuous with the
lining membrane of the bladder. The
epithelium is of the spheroidal or tran-
sitional character, stratified, and con-
taining, besides rounded cells, others
cylindrical and branched (Kolliker and
Luschka).
Vessels. — The ureter is supplied with blood from small branches of the renal, the
spermatic, the internal iliac, and the inferior vesical arteries. The veins end in various
neighbouring vessels.
The nerves come from the inferior mesenteric, spermatic, and hypogastric
plexuses.
Varieties. — Sometimes there is no funnel-shaped expansion of the ureter at its upper
end into a pelvis, but the calyces unite into two or more narrow tubes, which afterwards
coalesce to form the ureter. Occasionally, the separation of these two tubes continues
lower down than usual, and even reaches as low as the bladder, in which case the
ureter is double. In rare cases, a triple ureter has been met with.
In instances of long-continued obstruction to the passage of the urine, the ureters
occasionally become enormously dilated, and their opening into the bladder becomes
direct, so as to lose its valvular action.
944
THE URINARY BLADDER,
THE UKINARY BLADDER.
The urinary bladder (vesica urinaria) is a hollow membranous and
muscular viscus, which receives the urine poured into it through the ureters,
retains it for a longer or shorter period, and finally expels it through the
urethra.
During infancy it is pyriform, and lies chiefly in the abdomen, but in the
adult it is situated in the pelvic cavity behind the pubes, and in the male,
in front of the rectum ; in the female, it is separated from the rectum by
the uterus and vagina.
The size and shape of the bladder, its position in the abdomino-pelvic
cavity, and its relations to surrounding parts, vary greatly, according to its
state of distension or collapse. When quite empty, the bladder lies deeply in
the pelvis, and in a vertical antero-posterior section presents a triangular ap-
pearance, being flattened before and behind, having its base turned downwards
Fig. 664.
Fig. 664. — LATERAL VIEW OP THE VISCERA OF THE MALE PELVIS (after Quain). i
The left os ilium has been disarticulated from the sacrum, the spinous process of the
ischium cut through, and the pubes divided to the left of the symphysis ; a, the bladder;
6, b', the rectum ; c, membranous part of the urethra ; dt section of the left crus or
corpus cavernosum ; e, bulb of the spongy body of the urethra ; /, Cowper's gland; g,
section of the body of the pubes ; ht sphincter ani muscle ; *, part of the left vas
deferens ; m, articular surface of the sacrum ; n, divided spine of the ischium ; o,
coccyx ; p, prostate gland ; r, r, peritoneum ; /, recto-vesical pouch ; u, left ureter ; ??,
left vesicula seminalis.
and backwards, whilst its apex reaches up behind the symphysis pubis (fig.
601). The surfaces named anterior and posterior have thus a considerable
inclination. When moderately full, it is still contained within the pelvic
cavity, and has a -rounded form ; but when completely distended, it rises
above the brim of the pelvis, and becomes egg-shaped ; its larger end, which
is called the base or inferior fundus, being directed towards the rectum
FORM AND POSITION OF THE BLADDER. 945
in the male and the vagina in the female ; and its smaller end, or summit,
resting against the lower part of the anterior wall of the abdomen. Imme-
diately in front of the base is the thickened portion named the cervix, or
necky which bounds the outlet of the bladder, and connects it below with
the urethra.
The long axis of the distended bladder is inclined obliquely upwards and
forwards from the base to the summit, in a line directed from the coccyx
to a point between the pubes and the umbilicus. In being gradually dis-
tended, the bladder curves slightly forwards, so that it becomes more convex
behind than in front, and its upper end is by degrees turned more and more
towards the front of the abdomen. Lastly, the bladder, when filled, appears
slightly compressed from before backwards, so that its diameter in that
direction is less than from side to side. Kohlrausch states that, when the
bladder is filled during life, it has the shape of a flattened spheroid ; and
that, owing to pressure of the intestines from above, and the gravitation of
fluid in its interior, its vertical diameter is the shortest. In its ordinary
state, the longest diameter in the male is from base to summit ; but in the
female its breadth is often greater than its height. The average capacity
of the bladder is often stated to be greater in the female than in the male ;
and, no doubt, instances of very large female bladders are not unfrequent,
but these have probably been the result of unusual distension : in the
natural condition, according to Luschka and Henle, the female bladder is
decidedly smaller than that of the male.
While freely movable in all other directions upon surrounding parts, the
bladder is fixed below to the walls of the pelvis by the neck, and by reflec-
tions of the recto- vesical fascia, named the true ligaments of the bladder. It
is supported, moreover, by strong areolar connections with the rectum or
vagina, according to the sex, also in a slighter degree by the two ureters, tho
obliterated hypogastric arteries and the urachus, by numerous blood-vessels,
and, lastly, by a partial covering of the peritoneum, which, in being reflected
from this organ in different directions, forms certain folds or duplicatures,
named the false ligaments of the bladder.
The anterior surface is entirely destitute of peritoneum, and is in
apposition with the triangular ligament of the urethra, the subpubic liga-
ment, the symphysis and body of the pubes, and, if the organ be full, the
lower part of the anterior wall of the abdomen. It is connected to these
parts by loose areolar tissue, and to the back of the pubes by two strong
bands of the vesical fascia, named the anterior true ligament*. This surface
of the bladder may be punctured above the pubes without wounding the
peritoneum.
The posterior surface of the bladder is entirely free, and covered every-
where by the peritoneum, which in the male is prolonged also for a short
distance upon the base of the bladder. In the male, this surface is in con-
tact with the rectum, and in the female with the uterus, some convolutions
of the small intestine descending between it and those parts, unless the
bladder be very full. Beneath the peritoneum, in the male, a part of the
vas deferens is found on each side of the lower portion of this surface.
The summit (sometimes named the superior fundus) is connected to the
anterior abdominal wall by a tapering median cord, named the urachus,
which is composed of fibro-areolar tissue, mixed at its base with some
muscular fibres which are prolonged upon it from the bladder. This cord,
becoming narrower as it ascends, passes upwards from the apex of the
bladder between the linea alba and the peritoneum, to reach the umbilicus,
946
THE URINARY BLADDER.
where it becomes blended with the dense fibrous tissue found in that situa-
tion. The urachus, which forms in the early foetal state a tubular com-
munication between the urinary bladder and the allantoid vesicle, preserves,
according to Luschka, vestiges of ifr.s original condition in the form of a
long interrupted cavity, with irregularities and dilatations, lined with epi-
thelium similar to that of the bladder, and sometimes communicating by a
fine opening with the vesical cavity (Virchow's Archiv., 1862, and Anat. d.
Mensch., vol. ii., p. 229.)
The sides of the bladder, when it is distended, are rounded and prominent,
and are each of them crossed obliquely by the cord of the obliterated hypo-
gastric artery, which is connected posteriorly with the superior vesical
artery, and runs forwards and upwards to the umbilicus, approaching
the uraehus above the summit of the bladder. Behind and above this cord
the side of the bladder is covered with the peritoneum, but below and in
front of it the peritoneum does not reach the bladder, which is here con-
nected to the sides of the pelvic cavity by loose areolar tissue containing
fat, and, near its anterior and lower part, by the broad expansion from the
recto-vesical fascia, forming the lateral true ligament. The vas deferens
crosses obliquely the lower part of this lateral surface, from before backwards
and downwards, and turning over the obliterated hypogastric artery, de-
scends upon the inner side of the ureter, along the posterior surface, to the
base of the bladder.
Fig. 665.
Fig. 665. — BASE OF THE MALE
BLADDER WITH THE VESICULJE
SEMTNALES, VASA DEFERENTIA
AND PROSTATE EXPOSED (from
Haller). |
a, line of reflection of the peri-
toneum in the recto-vesical pouch ;
&, the part above this from- which
the peritoneum has been removed,
exposing the longitudinal mus-
cular fibres ; i, left vas deferens
ending in e, the left ejaculatory
duct ; s, left vesicula seminalis
joining the same duct ; the right
vas deferens, and the right vesi-
cula seminalis, marked s, s, un-
ravelled, are also shown ; p,
under side of the prostate gland ;
m, small part of the membra-
nous portion of the urethra ; u, u,
the ureters, of which the right is
turned to the side.
The base or fundus (in-
ferior fundus) is the widest
part of the bladder. It
is directed backwards as well as downwards, and differs according to the
sex in its relations to other parts. In the male it rests upon the second
portion of the rectum, and is covered posteriorly for a short space by the
peritoneum, which, however, is immediately reflected from thence upon
the rectum, so as to form the recto-vesical pouch. In front of the line
of reflection of the serous membrane, the base of the bladder is destitute
of peritoneum, and adherent to the rectum by dense fibro-areolar tissue
NECK OF THE BLADDER. LIGAMENTS. 947
over the extent of a triangular area bounded at the sides by the vasa defer -
eutia and vesiculae seminales, whilst its apex in front reaches the prostate
gland. It is in this space, which in the natural state of the parts is by no
means so large as it appears after they are disturbed in dissection, that
the bladder may be punctured from the rectum without injury to the peri-
toneum. In the female, the base of the bladder is of less extent, and does
not reach so far back in the pelvis as in the male ; for it rests agaiust the
front of the neck of the uterus and the anterior wall of the vagina, both of
which organs intervene between it and the rectum. This part of the
bladder adheres to the vagina, and above that adhesion the peritoneum
forms a pouch between it and the uterus, much shallower than the recto-
vesical pouch of the male.
The cervix or neck of the bladder is a term commonly applied to the part
of the bladder at which the cavity terminates in the urethra, and is often
indefinitely used, so as to include a considerable portion either of the
bladder or urethra. It may be conveniently retained to denote the region
of the immediate neighbourhood of the urethral orifice. It is the most
strongly muscular part of the bladder, and in the male it is closely con-
nected with the base of the prostate gland, by which it is supported. It
was formerly described as an infundibular projection, but, as pointed out
by Kohlrausch, no such arrangement exists. The urethral orifice is in both
sexes the part of the bladder which in the erect posture is lowest ; it lies
at the angle of meeting of the base and the anterior surface.
It was formerly believed that the base was the lowest part of the bladder in the
adult male, and hence the origin of the term. The inferior position of the urethral
orifice was supposed to be peculiar to women and children. The more correct views,
however, now entertained with respect to the inclination of the pelvis (p. 98), have led
to altered notions of the relative elevation of the pelvic viscera. A consideration of the
following circumstances will aid the formation of an accurate conception of the position
of the vesical outlet. The symphysis pubis is placed very obliquely ; the ischial
tuberosities are little lower than the inferior margin of the symphysis pubis, and
the triangular ligament is therefore almost horizontal ; the lower part of the sacrum
and the coccyx are nearly vertical, being only slightly curved forwards, and the tip of
the coccyx is on a somewhat higher level than the inferior margin of the symphysis
pubis ; the curve and position of the rectum are determined by those of the sacrum
and coccyx, until it passes in front of the coccyx, when it turns vertically downwards ;
the prostate gland, situated entirely on the upper or deep side of the triangular liga-
ment, rests on the last turn of the rectum, and the base of the bladder is in contact
with the rectum above that place.
Ligaments of the bladder. — The true ligaments of the bladder, four in
number, two anterior and two lateral, all derived from the vesicai portion
of the recto-vesical fascia, have been already described (p. 260).
The false ligaments or peritoneal folds are described as five in number.
Two of them, named posterior false ligaments or recto-vesical folds, run
forwards in the male along the sides of the rectum to the posterior and
lateral aspect of the bladder, and bound the sides of the recto-vesical
cul-de-sac. In the female these posterior folds pass forwards from the sides
of the uterus, and are comparatively small. The two lateral false ligaments
extend from the iliac fossse to the sides of the bladder, each separated from
the corresponding posterior ligament by a prominent angle in which the
obliterated hypogastric artery lies. The superior false ligament (ligamentum
suspeusorium) is the portion of peritoneum between the ascending parts of
the epigastric arteries, and reaches from the summit of the bladder to the
umbilicus.
3 Q 2
948 THE URINARY BLADDER.
Interior of the Bladder. — On opening the bladder, its internal surface is
found to be lined by a smooth membrane, which is so loosely attached to
the other coats, that in the flaccid condition of the organ it is nearly every-
where thrown into small wrinkles or folds, which disappear as soon as the
bladder is distended. Besides these, the interior of the bladder is often
marked by reticular elevations or ridges, corresponding with the fasciculi
of the muscular coat.
At the lower and anterior part of the bladder is seen the orifice leading
into the urethra, round which the mucous membrane is corrugated longi-
tudinally. Immediately behind the urethral opening, at the anterior part
of the fund us, is a small smooth triangular surface, having its apex turned
forwards, which, owing to the firmer adhesion of the mucous membrane
to the subjacent tissues, never presents any rugse, even when the bladder
is empty. This surface is named the trigone (trigonum vesicse, Lieutaud) ;
at its posterior angles are the orifices of the two ureters, situated about
an inch and a half from each other, and nearly the same distance from the
anterior angle, where the bladder opens into the urethra (fig. 673).
The orifices of the ureters, presenting the appearance of oval slits, are
directed obliquely forwards and inwards : they are united by a curved
elevation which extends generally outwards and backwards beyond them,
and which corresponds in position with a muscular band which joins them
together and to the neck of the bladder. Proceeding forwards from opposite
the middle of this, is another slight elevation of the mucous surface, named
the uvula vesicce (luette vesicale), which projects from below into the ure-
thral orifice. In the female, the trigone is small, and the uvula indis-
tinct. In the male, the uvula lies a little in advance of the middle lobe
of the prostate, and is sometimes prolonged on the floor of the prostatic
portion of the urethra. It is formed by a thickening of the submucous
tissue. In its natural state this may contribute to the more perfect closure
or apposition of the sides of the orifice of the bladder, and when enlarged
by disease it frequently produces serious obstruction at the commencement
of the urethra.
Structure. — The bladder is composed of a serous, a muscular, and a
mucous coat, united together by areolar tissue, and supplied with numerous
blood-vessels and nerves.
The serous or peritoneal coat is a partial covering, investing only the
posterior and upper half of the bladder, and reflected from it upon the sur-
rounding parts in the manner already described in detail.
The muscular coat consists of pale unstriped involuntary muscular fibres,
so arranged as to warrant the usual description of them as forming layers,
the outer of which consists of fibres more or less longitudinal, and the
next, of fibres more circular in disposition ; while, beneath this, is another
delicate longitudinal layer more recently recognised.
The external or longitudinal fibres are most distinctly marked on the
anterior and posterior surfaces of the bladder. Commencing in front at the
neck of the organ, from the pubes in both sexes (musculi pubo-vesicales,
p. 265), and, in the male, from the adjoining part of the prostate gland,
they may be traced upwards along the anterior surface to the summit of the
bladder ; and they may likewise be followed down over the posterior
surface and base to the under part of the neck of the bladder, where they
become attached to the prostate in the male, and to the front of the vagina
in the female. Upon the sides of the bladder the superficial fasciculi run
more or less obliquely, and often intersect one another : in the male they
MUSCULAR COATS. CIRCULAR FIBRES.
949
reach the sides of the prostate. At the summit a few are continued along
the urachus. The longitudinal fibres, taken together, constitute what has
been named the detrusor tirince muscle.
The so-called circular fibres form a thin and somewhat irregular reticulated
layer distributed over the body of the bladder, having various appearances
in different bladders. Their course may in general be looked upon as trans-
verse, but for the most part throughout the upper two-thirds of the bladder
they cross one another in very oblique bands : towards the lower part of the
organ they assume a more circular course, and upon the fundus and trigouo
form a tolerably regular layer. Close to and around the cervix, in immediate
connection with the prostate in the male, they densely encircle the orifice
and constitute what has been named the sphincter vesicce, which, however, is
not distinct from the other fibres.
Fig. 666.
Fig. 666, A. — VIEW OF THE MUSCULAR FIBRES OP THE BLADDER FROM BEFOKE (after
Pettigrew and from Nature). £
On the right side the superficial fibres are shown ; on the left the deep or circular
fibres chiefly are displayed, a, on the right side, the median and most superficial
bauds of the longitudinal fibres, iu which a slight decussatiou of fibres is seen indicating
Pettigrew's longest figure-8 loops ; a, those diverging somewhat ; a", the lowest,
which pass much more obliquely ; the attachment of the longitudinal fibres to the prostate
is shown ; on the left side c, the upper, </, the middle, and c", the lowest set of circular or
deeper fibres ; at s, the thickest and most transverse sets of these fibres forming the
sphincter ; p, half the prostate left on the right side, the left having been removed ; uy the
urachus, into which some of the longitudinal fibres are seen prolonged.
Fig. 666, B. — VIEW OF THE MUSCULAR FIBRES OF THE BLADDER FROM BEHIND
(after Pettigrew and from Nature). £
On the right side the superficial fibres are displayed ; on the left the deeper fibres of
the same kind or intermediate fibres, and some of the circular fibres ; b, b, the median,
most superficial and strongest bands of longitudinal fibres on the right side ; b', the
more diverging set of fibres near the middle of the bladder ; b", the most divergent
fibres which surround the entrance of the ureters ; on the left side, c, c', and c", indicate
the deeper circular fibres passing round at various levels and crossing with the deeper
diverging fibres posteriorly; s, the most transverse fibres at the neck forming the
sphincter ; u, the urachus ; ur, the ureters ; the left half of the prostate has been
removed to show the sphincter ; v, part of the right vas deferens and vesicula seminalis.
950
THE URINARY BLADDER.
The third stratum of fibres, still more deeply situated, and which might be
termed internal longitudinal, was first described by Ellis, who distinguished
it as "submucous." It is very delicate, and its fibres, directed longitu-
dinally, are scattered in a regular manner round the cavity of the bladder.
The researches of Pettigrew (including an elaborate series of dissections
preserved in the Museum of the Royal College of Surgeons of England)
have led him to the conclusion that, with few exceptions, the muscular
fibres of all the strata are arranged in figure-8 loops. These loops are
directed towards the apex and base, and he regards them as disposed in
four sets ; an anterior and a posterior set largely developed, and a right and
a left lateral set accessory and less fully developed ; and they are so arranged
that at any one spot on the bladder there are to be found decussating
groups of fibres, which may be distinguished as longitudinal, horizontal or
transverse, and oblique. The extremities of each figure-8 are placed on one
aspect of the bladder, and the point of decussation on the opposite aspect ;
the arrangement being thus similar to that of a string wound in figure-3
loops round a cylinder. In each set the most superficial loops are com-
pressed laterally and elongated from above downwards, but the succeeding
loops as they become more deeply placed are more and more drawn out trans-
versely until those which are nearly circular are reached ; and on passing more
deeply than these, the loops become again gradually more and more elongated
until those which have been alluded to as internal longitudinal are arrived at.
The figure-8 arrangement, stated by Pettigrew to exist in all the groups, is
moat distinctly seen in the anterior set, which may here be more particularly
alluded to. The most superficial fibres of. this set form a narrow band some
of which are prolonged on the urachus, while others pass round close behind
its insertion ; their decussation takes place about midway between the
summit of the bladder and the urethra ; and inferiorly they pass forwards
to be inserted into the capsule of the prostate, the posterior surface of the
pubes, the inner border of the levator ani, and the fascia covering the
constrictor urethras muscle. The points of decussation of the deeper fibres
Fig. 667.
Fig. 667.— VIEW OP THE MUSCULAR
FIBRES OP THE BLADDER FROM THE
LEFT SIDE (after Pettigrew and
from Nature). £
The anterior and posterior super-
ficial fibres are seen in profile running
from below upwards, crossing each
other by their divergence on the sides
of the bladder, and are indicated by
the same letters as in the previous
figures ; at c, a portion of the anterior
longitudinal fibres has been removed so
as to expose the deeper circular fibres.
as they become more horizontal,
are placed lower and lower down.
The fibres which cross obliquely
are most expanded, and embrace
the larger parts of the bladder,
taking part, on the posterior
wall, in the formation of the so-
called circular layer, while the fibres which at their decussation are more
nearly horizontal are confined to the regions of the base and neck. The
COATS OF THE BLADDER. MUCOUS MEMBRANE. 951
•whole of the muscular fibres around the prostate and prostatic portion of the
urethra are supposed by Pettigrew to be formed by the lower extremities of
the various figures-8. The general idea of this figure-8 arrangement was
first suggested by Sabatier, by whom the more marked examples of it are
described ; but it has been fully elaborated by the researches of Pettigrew.
A strong muscular bundle already alluded to passes, as shown by Ellis,
with its convexity forwards between the terminations of the ureters, con-
tinuous with the longitudinal fibres of these tubes. Other fibres mentioned
by Morgagni, and more fully described under the name of the " muscles of
the ureters " by Sir C. Bell, pass forwards from the ureters towards the
urethra : they are considered by Pettigrew not as special structures, but
as a part of the general arrangement of fibres in that part of the bladder.
On the muscular arrangements of the bladder, see Pettigrew, in Phil.
Trans, for 1866 ; Sabatier, Kech. Anat. et Phys. sur les Appareils
musculaires correspondents k la vessie et k la prostate dans les deux *<exes,
1864 ; and in Henle's Jahresbericht ; Ellis, in Trans. Med. Chir. Society,
1856, and Demonstrations, 1861.
The muscular coat of the bladder forms so irregular a covering, that, when the organ
is much distended, intervals arise in which the walls are very thin; and, should the
internal or mucous lining protrude in any spot through the muscular bundles, a sort
of hernia is produced, which may go on increasing, so as to form what is called a
vesieal sacculus, or appendix vesicce, the bladder thus affected being termed sacculated.
Hypertrophy of the muscular fasciculi, which is liable to occur in stricture of the
urethra or other affections impeding the issue of the urine, gives rise to that condition
named the fasciculated bladder, in which the interior of the organ is marked by strong
reticulated ridges or columns, with intervening depressions.
Next to the muscular coat, between it and the mucous membrane, but
much more intimately connected with the latter, is a well-marked layer of
areolar tissue,, frequently named the cellular or vascular coat. This sub-
mucous areular layer contains a large quantity of very fine coiled fibres of
elastic tissue.
The mucous membrane of the bladder is soft, smooth, and of a pale rose
colour. It is continuous above with the lining membrane of the ureters
and kidneys, and below with that of the urethra. It adheres loosely to
the muscular tissue, and is thus liable to be thrown into "wrinkles, except at
the trigoue, where it is consequently always more even. It is covered
with a stratified epithelium, the particles of which are intermediate in form
between those of the columnar and squamous varieties. There are no villi
upon the vesical mucous membrane, but it is provided with minute follicles,
and small racemose glands lined with columnar epithelium, which are most
abundant in the vicinity of the neck of the bladder. The vesical mucus
(according to Mandl) is alkaline, and appears to contain alkaline and earthy
phosphates.
Vessels. — The superior vesical arteries proceed from the remaining pervious
portions of the hypogastric arteries; in the adult they appear as direct branches
of the internal iliac. The inferior vesical arteries are usually derived from the anterior
division of the internal iliac. In the female the uterine arteries also send branches to
the bladder. The neck and base of the organ appear to be the most vascular portions.
The veins form large plexuses around the neck, sides and base of the bladder; they
eventually pass into the internal iliac veins. The lymphatics follow a similar course.
The nerves are derived partly from the hypogastric plexus of the sympathetic, and
partly from the sacral plexus of the cerebro-spinal system. The former are said to he
chiefly distributed to the upper part of the bladder, whilst the spinal nerves may be.
traced more directly to its neck and base.
952 MALE ORGANS OF GENERATION.
THE URETHRA.
The urethra is a membranous tube directed in the median line, first verti-
cally and then from behind forwards, beneath the arch of the pubes, in
which situation it opens in the female into the vulva, while in the male it is
enclosed in the spongy substance and prolonged beneath the corpora caver-
nosa penis. In the female, it serves simply as the excretory passage for the
urine ; in the male, it conducts also the seminal fluid. The detailed
anatomy of the male and female urethra will be given with that of the
organs of generation of the respective sexes.
ORGANS OF GENERATION.
THE MALE ORGANS OF GENERATION.
THE male organs of generation include, together with the testes and their
proper excretory apparatus, a series of structures which for convenience
may be considered first, as they are closely connected with the urethra.
Thus, at its commencement the urethra passes through the prostate gland,
and there it receives the excretory ducts of the testes and vesiculse semi-
nales ; emerging from the prostate, it traverses the layers of the subpubic
fascia supported by muscles, and, becoming copiously surrounded with
the erectile tissue of the corpus spongiosum, is pierced by the ducts of
Cowper's glands, and afterwards, in conjunction with the corpora cavernosa,
enters into the formation of the penis.
THE PROSTATE GLAND.
The prostate gland is a firm glandular body, somewhat resembling a
chestnut in shape and size, which supports the neck of the bladder and
encloses the commencement of the urethra : it is placed in the pelvic cavity,
on the deep aspect of the subpubic fascia, and rests upon the rectum. It
has the form of a flattened cone with its base in contact with the bladder,
and cut obliquely, so that its posterior or rectal surface is much larger than
its anterior or pubic surface. It usually measures about an inch and a
half across at its widest part, an inch and a quarter from its base to its
apex, and nearly an inch in depth or thickness. Its ordinary weight is
about six drachms.
The anterior or pubic surface of the prostate is flattened and marked
with a slight longitudinal furrow ; it is about half an inch or rather more
from the pubic symphysis, and there, as well as the sides of the gland, is con-
Fig. 668. . Fig. 668.— TRANSVERSE SECTION OP THE PROS-
TATE GLAND THROUGH THE MIDDLE.
u, the urethra, into which the eminence of the
caput gallinaginis rises from below ; s, the sinus
poculaxis, cut through ; d e, the ejaculatory ducts ;
m, superiorly, the deep sphincter muscular fibres ;
ra, lower down, intersecting muscular bands in the
lateral lobes of the prostate ; p, p, glandular sub-
stance.
nected to the pubic arch by the reflexion
of the pelvic fascia, which forms the
pubo-prostatic ligaments or anterior ligaments of the bladder. The pos-
terior or rectal surface is smooth, and is marked by a slight depression,
FORM OF THE PROSTATE GLAND. 953
or by two grooves, which meet ID front, and correspond with the course of
the seminal ducts, as well as mark the limits of the lateral lobes in this
situation : it is in close apposition with the rectum, immediately in front
of the bend from the middle to the lower or anal part of that viscus,
where the surface and posterior border of the gland can be felt by the
finger introduced into the intestine. The sides are convex and prominent,
and are covered by the anterior portions of the levatores ani muscles, which
pass back on each side, from the symphysis pubis and anterior ligament
of the bladder, and embrace the sides of the prostate. This part of
each levator ani is occasionally separated from the rest of the muscle by
areolar tissue, and has been named levator prostatce. The base of the gland
is of considerable thickness, and is notched in the middle : its apex is
turned towards the triangular ligament. As already stated, the prostate
encloses the commencement of the urethra. The canal runs nearer to the
upper than to the under surface of the gland, so that in general it is about
three lines distant from the former and four or five from the latter ; but
it frequently varies greatly in this respect. The prostatic portion of the
urethra is about an inch and a quarter long, and is dilated in the middle ;
it contains the verumontanum and the openings of the seminal and prostatic
ducts, and will be afterwards more particularly described. The common
seminal ducts, which pass forwards from the vesiculse seminales, also traverse
the lower part of the prostate, enclosed in a special canal, and open into the
urethra.
Fig. 669.
Fig. 669. — LONGITUDINAL MEDIAN SECTION OF THE LOWER PART OF THE BLADDER
AND PROSTATE GLAND (after E. H. Weber).
17, inner surface of the urinary bladder ; u r, opening of the right ureter, from which
a slight elevation runs down to the neck of the bladder ; p, upper part of the prostate ;
p', the so-called middle lobe ; p", the right lateral lobe ; u, the utricle or sinus pocularis ;
d, the right ejaculatory duct; v d, vas deferens ; v s, vesicula seminalis.
This gland is usually described as consisting of three lobes, two of which,
placed laterally and separated behind by the posterior notch, are of equal
954 MALE ORGANS OF GENERATION,
size ; the third, or middle lobe, is a smaller rounded or triangular mass,
intimately connected with the other two, and fitted in between them on the
under side, lying immediately beneath the neck of the bladder and the
adjacent part of the urethra. This third lobe is exposed by turning down
the seminal vesicles and ducts, between which and the cervix vesicse it is
placed ; being in fact the part of the gland contained between and behind
the grooves or fissures by which the ejaculatory ducts reach the urethra.
The separation between these lobes, which is little marked in the natural
state, becomes often much more apparent in disease.
Structure. — The prostate is enclosed in a dense fibrous coat, which is
continuous with the recto-vesical fascia, and with the posterior layer of
the triangular ligament, and is rather difficult to tear or cut. Adams
describes the fibrous capsule as divisible into two layers, between which
the prostatic plexus of veins is enclosed. The prostate is a highly muscular
organ ; its external coat contains numerous plain fibres ; within the proper
glandular structure, which lies somewhat superficially, there is a strong
layer of circular fibres continuous posteriorly with the sphincter vesicse.
Ellis finds that these muscular fibres not only join behind with the circular
fibres of the bladder, but are continuous in front with the thin layer hereafter
described around the membranous part of the urethra (p. 962). According
to Pettigrew, the muscular fibres of the prostate are the lower parts of
figure-8 loops, which spread superiorly on the bladder. The substance
of the gland is spongy and more yielding ; its colour is reddish grey, or
sometimes of a brownish hue. It consists of numerous small follicles or
terminal vesicles opening into elongated canals, which unite into a smaller
number of excretory ducts. These appear either as pores or as whitish
streaks, according to the way in which they are exposed in a section. The
epithelium in the vehicular terminations is thin and squamous, whilst in the
canals it is columnar. The capillary blood-vessels spread out as in other
similar glands on the ducts and clusters of vesicles, and the different glan-
dular elements are united by areolar tissue, and supported by processes of
the deep layer of the fibrous capsule (Adams). The ducts open by from
twelve to twenty or more orifices upon the floor of the urethra, chiefly in
the hollow on each side of the verumontanum (p. 963). — (Adams, Cyclop,
of Anat., vol. iv., p. 147 ; Ellis and Pettigrew, referred to at p. 951.)
Vessels and Nerves. — The prostate is supplied by branches of the vesical,
hsemorrhoidal, and pudic arteries. Its veins form a plexus round the sides
and base of the gland, which is highly developed in old subjects. These
veins communicate in front with the dorsal vein of the penis, and behind
with branches of the internal iliac vein. According to Adams, the lym-
phatics, like the veins, are seen ramifying between the two layers of the
fibrous capsule. The nerves are derived from the hypogastric plexus.
Prostatic fluid. — This is mixed with the seminal fluid during emission; as obtained
from the human prostate soon after death, it has a milky aspect, which is ascribed
by Adams to the admixture of a large number of epithelial cells, and he thinks it pro-
bable that, as discharged during life, it is more transparent. According to the same
observer, the prostatic fluid has an acid reaction, and presents, under the microscope,
numerous molecules, epithelial particles both squamous and columnar, and granular
nuclei about -^m inch in diameter. As age advances, this gland is disposed to become
enlarged; and its ducts often contain small round concretions of laminated appear-
ance, and varying from a small size up to that of a millet-seed; they sometimes con-
tain carbonate of lime, but are principally composed of animal matter, which in some
of them appears to be entirely amylaceous, in others albuminous, and more frequently
is of a mixed character. (Virchow's Cellular Pathology, by Chance, p. 369.)
FORM OF THE PENIS. INTEGUMENTS. 955
THE PENIS.
The penis, which supports the greater part of the urethra in the male,
ia composed principally of an erectile tissue, arranged in masses which
occupy three loug and nearly cylindrical compartments. Of these, two,
named corpora cavernosa peuis, placed side by side, form the principal part
of the organ, whilst the other, situated beneath the two preceding, sur-
rounds the canal of the urethra, and is named corpus cavernosum urethrce or
corpus spongiosum.
The penis is attached behind to the front of the pubes, and to the pubic
arch, by what is termed the root ; in front it ends in an enlargement named
the glans, which is structurally continuous with the corpus spongiosum. The
intermediate portion or body of the penis, owing to the relative position of
its three compartments, has three somewhat flattened sides, and three
rounded borders ; its widest side is turned upwards and forwards, and is
named the dorsum. The glans penis, which is slightly compressed above
and below, presents at its extremity a vertical fissure, the external orifice
of the urethra ; its base, which is wider than the body of the penis, is
hollowed out below to receive the narrowing extremities of the corpora
caveruosa ; its border is rounded and projecting, and is named the corona
glandiSj behind which is a constriction named the cervix ; the posterior
boundary of the glans thus marked off passes obliquely down on each side
of the under surface, and ends behind the urethral opening, in a median
fold of skin, named the frcenum.
The Integuments. — The integument of the penis, which is continued from
that of the pubes and scrotum, forms a simple investment as far as the
neck of the glans. At this part it leaves the surface and is doubled
up in a loose cylindrical fold, constituting the prepuce or foreskin. The
inner layer of this fold returns to the penis behind the cervix, where it
is firmly attached ; and the integument, becoming thus again adherent, is
continued forwards over the corona and glans, as far as the orifice of the
urethra, where it meets with the mucous membrane of the urethra, and
behind that orifice forms the frcenum of the prepuce. Upon the body of the
penis the skin is very thin, entirely free from fat, and, excepting at the
root, from hairs also ; in these respects differing remarkably from that on
the pubes, which is thick, covers a large cushion of fat, and, after puberty,
is beset with hairs : the skin of the penis is moreover very movable and
distensible, and is dark in colour. At the free margin of the prepuce the
integument changes its character, and approaches to that of a mucous
membrane, being red, thin and moist. Numerous sebaceous glands are
collected round the cervix of the penis and corona ; they are named the
glands of Tyson (glandulse ordoriferse). Their secretion has a peculiar odour,
and was formerly supposed to constitute the white smegma prceputii, which
tends to collect beneath the foreskin ; but that substance consists princi-
pally of epithelial cells cast from the opposed cuticular surfaces.
Upon the surface of the glans penis the integument again changes its
character ; it ceases to contain glands, but its papillae are highly developed
and extremely sensitive, and it adheres most intimately and immovably to
the spongy tissue of the glans.
Beneath the skin, on the body of the penis, the ordinary superficial fascia ia
very distinct ; it is continuous with that of the groin, and also with the dartoid
tissue of the scrotum. Near the root of the organ there is in front a dense
band of fibre-elastic tissue, named the suspensory liyament, lying amongst
956
MALE ORGANS OF GENERATION.
the fibres of the superficial fascia ; it is triangular in form ; one edge is
free, another is connected with the fore part of the pubic symphysis, and
the third with the dorsum of the penis.
The integuments of the penis are supplied with blood by branches of the
dorsal artery of the penis and external pudic ; the veins join the dorsal and
external pudic veins. Their nerves are entirely derived from the dorsal
branches of the pudic nerves.
THE CORPORA CAVERNOSA.
The corpora cavernosa form the principal part of the body of the penis,
and chiefly determine its form and consistence. They are two cylindrical
bodies, placed side by side, flattened on their median aspects, and closely
united and in part blended together along the middle Hue for the anterior
three-fourths of their length ; whilst at the back part, in contact with the
symphysis pubis, they separate from each other in form of two bulging and
Figi 670. FiS- 670.— ROOT OF THE PENIS ATTACHED
TO THE RAMI OF TUB PuBES AND
ISCHIUM (from Kobelt). f
a, a, accelerator urinae muscle covering
the bulb of the spongy body of the urethra,
which presents at e, posteriorly, a median
notch ; b, 6, anterior slips of the muscle
or bulbo-cavernosi ; c, c, crura of the
penis, presenting an oval dilatation, g, or
bulb of the corpus cavernosum ; d, d,
erectores penis muscles ; /, corpus spon-
giosum urethra.
then tapering processes named cntra,
which extend backwards attached
to the pubic and ischial rami, and
invested by the erectores penis or
ischio-cavernosi muscles. Imme-
diately behind their place of union,
they are slightly enlarged, so as to
form what are named by Kobelt
the bulbs of the corpora cavernosa,
parts which attain a much greater
proportionate development in some
quadrupeds. In front, the corpora
cavernosa are closely bound together
into a single rounded extremity, which is covered by the glans penis and
firmly connected to its base by fibrous tissue.
The under surface of the united cavernous bodies presents a longi-
tudinal groove, in which is lodged the corpus spongiosum, containing the
greatest part of the canal of the urethra. The upper or anterior surface is
also marked with a slight median groove for the dorsal vein of the penis,
and near the root is attached to the pubes by the suspensory-ligament.
Structure. — The median septum between the two corpora caveruosa is
thick and complete behind ; but farther forward it becomes thinner, and
imperfectly separates their two cavities, for it presents, particularly towards
the anterior extremity, numerous clefts, extending from the dorsal to the
urethral edge, and admitting of a free communication between the erectile
STRUCTURE OF THE CORPORA CAVERXOSA.
957
tissue of the two sides. From the direction of these slits, the intermediate
white portions of the septum are made to resemble in arrangement the teeth
of a comb, and hence it is named *eptum pectiniforme.
The external fibrous investment of the cavernous structure is white and
dense, from half a line to a line thick, and very strong and elastic. It is
composed for the most part of longitudinal bundles of shining white fibres,
with numerous well-developed elastic fibres, enclosing the two corpora
caverriosa in a common covering ; but internal to this, in each compartment,
is a layer of circular fibres, which enter into the formation of the septum.
(J. Wilson and Ellis.)
From the interior of the fibrous envelope, and from the sides of the
septum, numerous lamellse, bands, and cords, composed of au extensible
fibrous tissue, and named trabeculce, pass inwards, and run through and
across the cavity in all directions, thus sub-
dividing it into a multitude of interstices, and Fig. 671.
giving the entire structure a spongy character.
Fig. 671. — TRANSVERSE SECTION OP THE PENIS IN THE
DISTENDED STATE.
The integument is represented as surrounding the
deeper parts ; the erectile tissue occupying the corpora
cavernosa and the septum pectiniforme descending be-
tween these bodies ; u, placed on the section of the
spongy hody, marks the urethra in the form of a trans-
verse slit ; v, the single dorsal vein ; a, the dorsal
arteiy, and n, the nerve, of one side.
The trabeculae, whether lamelliform or cord-like, are larger and stronger
near the circumference than along the centre of each cavernous body, and
Fig. 672. — PORTION OP THE Fig. 672.
ERECTILE TISSUE OF THE
CORPUS CAVKRNOSUM MAG-
NIFIED, SHOWING THE AREO-
LAR STRUCTURE AND THE
VASCULAR DISTRIBUTION
(from J. Mullet).
a, a small artery supported
by the larger trabeculae, and
branching out on all sides ; c,
the tendril-like arterial tufts
or helicine arteries of Miiller ;
d, the areolar structure formed
by the finer trabeculae.
they also become gradually
thicker towards the crura.
The interspaces, conversely,
are larger in the middle
than near the surface ;
their long diameter is, in
the latter situation, placed
transversely to that of the
penis ; and they become
larger towards the forepart of the penis. They are lined by a layer of
squamous epithelium. The trabeculse contain the ordinary white fibrous
tissue and fine elastic fibres, together with pale muscular fibres, arteries, and
958 MALE ORGANS OF GENERATION.
nerves. The muscular tissue is much more abundant in the penis of some
animals than in man.
The iutertrabecular spaces form a labyrinth of intercommunicating
venous areolse divided by the trabecular tissue. The spaces of the two
sides communicate freely through the septum, especially in front. They
return their blood partly by a series of branches which escape between
the corpora cavernosa and the corpus spongiosum, and which, accompanied
by veins from the latter, mount on the sides of the penis to the vena
dorsalis, partly by short veins issuing at the upper surface, and imme-
diately joining the dorsal vein, but principally by veins passing out near
the root of the penis and joining the prostatic plexus and pudendal veins.
According to Kobelt, there are also communications with the cutaneous
veins on the abdomen.
The arteries of the corpora cavernosa are branches of the ptidic artery.
The proper cavernous arteries (profundse penis), right and left, supply them
chiefly ; but the dorsal artery of the penis also sends twigs through the
fibrous sheath, along the upper surface, especially in the fore part of the
penis. Within the cavernous tissue, the numerous branches of arteries are
supported by the trabeculsB, in the middle of which they run, and terminate
in two modes ; some of them subdividing into branches of capillary minute-
ness which open into the intertrabecular spaces ; while others form tendril-
like twigs which project into the spaces, and end in curling dilated extre-
mities— the helicine arteries of J. Muller, sometimes singly and sometimes
in tufts. The extremity of each curled dilatation would appear to be bound
down by a small fibrous band, which according to Henle is usually solid,
but is said by Kolliker to contain a capillary continuation of the blood-
Fig. 673. Fig. 673. — ONE OP THE TUFTS CONTAINING A HELICINE ARTERY
MORE HIGHLY MAGNIFIED (from J. Muller).
The tuft is represented as projecting into the cavity of a
vein.
vessel. The helicine arteries are most abundant in the
posterior part of the corpora cavernosa, and are found
in the corresponding part of the corpus spongiosum
also ; but they have not been seen in the glans penis.
They are most distinct in man, but are not constant in animals, so that,
whatever may be their use, they do not appear to be essential to the process
of erection.
CORPUS SPONGIOSUM.
The corpus spongiosum urethrce commences in front of the triangular
ligament of the perineum, between the diverging crura of the corpora
cavernosa, and somewhat behind their point of junction, by an enlarged and
rounded extremity named the bulb. It extends forwards as a cylindrical,
or slightly tapering body, lodged in the groove on the under side of the
united cavernous bodies, as far as their blunt anterior extremity, over
which it expands so as to form the glans penis already described.
The posterior bulbous extremity, or bulb of the urethra, varies in size in
different subjects. It receives an investment from the triangular ligament
in which it rests, and is embraced by the accelerator urinse, or bulbo-
cavernosus muscle. The posterior extremity of the bulb exhibits, more or
STRUCTURE OF THE CORPUS SPONGIOSUM. 959
less distinctly, a subdivision into two lateral portions or lobes, separated by
a slight furrow on the surface, and by a slender fibrous partition within,
which extends for a short distance forwards ; in early infancy this is more
marked. It is above this part that the urethra, having pierced the tri-
angular ligament, enters the bulb, surrounded obliquely by a portion of
the spongy tissue, named by Kobelt the colliculus bulbi, from which a layer
of venous erectile tissue passes back upon the membranous portion of the
urethra, and also upon the prostatic part, to the neck of the bladder, lying
closely beneath the mucous membrane. At first the urethra is nearer the
upper than the lower part of the corpus spongiosum, but it soon gains and
continues to occupy the middle of that body.
Structure. — This is essentially the same as that of the corpora caver-
nosa, only more delicate, or with a much less quantity of the fibrous
trabecular structure. Like the corpora cavernosa, it is distended with blood
during erection ; but never acquires the same hardness. The outer fibrous
tunic is much thinner, is less white in colour, and contains more elastic
tissue ; the areoloe are smaller, and directed for the most part with their
long diameter corresponding to that of the penis ; the trabeculas are finer
and more equal in size ; and the veins form a nearly uniform plexus
between them ; in the glans, the meshes of this plexus are smallest and
most uniform. Immediately surrounding the canal of the urethra, and,
again, forming part of the external coat of the spongy substance, there
are plain muscular fibres, which are continuous posteriorly with those of
the bladder. The helicine arteries are found in the spongy body, except-
ing in the part which forms the glans penis. A considerable artery derived
from the internal pudic enters the bulb on each side, and supplies the
greater part of the spongy body, sending branches as far as the glans penis,
which, however, is chiefly supplied by the arteria dorsalis. Besides these,
Kobelt describes, as constantly present, another but much smaller branch of
the pudic artery, which, he says, enters the bulb on the upper surface, about
an inch from its posterior extremity, and runs forwards in the corpus spongi-
osum to the glans. Veins issue from the glans and adjoining part of the
spongy body, to end in the vena dorsalis penis ; those of the rest of the
spongy body for the most part pass out backwards through the bulb, and
end in the prostatic and pudic venous plexuses : some emerge from beneath
the corpora cavernosa, anastomose with their veins, and end partly in the
cutaneous venous system of the penis and scrotum, and partly in the pudic
and obturator veins.
The lymphatics of the penis form a dense network on the skin of the
glaus and prepuce, and also underneath the mucous lining of the urethra.
They terminate chiefly in the inguinal glands. Deep-seated lymphatics are
also described as issuing from the cavernous and spongy bodies, and passing
under the pubic arch with the deep veins, to join the lymphatic plexuses in
the pelvis.
The nerves of the penis are derived from the pudic nerve and from the
hypogastric plexus of the sympathetic (pp. 671 and 703). They terminate
by frequent division, and present indistinct traces of the so-called corpuscula
tactus ; on the glans and bulb of the urethra, some fibres of the cutaneous
nerves end in Pacinian bodies.
URETHRA OF THE MALE.
The male urethra extends from the neck of the bladder to the extremity
of the penis. Its total length is about eight inches and a half, but varies
960
MALE ORGANS OF GENERATION.
much according to the length of the penis, and the condition of that organ.
Its diameter varies at different parts of its extent, as will be stated more
particularly hereafter. The tube consists of a continuous mucous mem-
Fig. 674.
Fig. 674. — THE LOWER PART OP THE BLADDER AND THE PROSTATIC, MEMBRANOUS, AND
BULBOUS PARTS OF THE URETHRA OPENED FROM ABOVE.
A portion of the wall of the bladder and the upper part of the prostate gland have
been removed, the corpora cavernosa penis have been separated in the middle line and
turned to the side, and the urethra has been slit up ; the bulb is left entire below, and
upon and behind it the glands of Cowper with their ducts have been exposed, t, placed
in the middle of the trigonum vesicse ; u, u, oblique apertures of the ureters ; from these
an elevation of the wall of the bladder is shown running down to uv, the uvula vesicse; I,
the longitudinal muscular fibres of the bladder passing down upon the prostate ; s v, the
circular fibres of the sphincter surrounding the neck ; p, the glandular part of the pros-
tate ; p', the prostatic portion of the urethra ; from the uvula vesicae a median ridge is
seen descending to the caput gallinaginis, in which s, indicates the opening of the
sinus pocularis, and d, that of one of the ductus ejaculatorii ; m, the commencement of
the membranous portion of the urethra ; &, the bulb of the spongy body ; b', the bulbous
part of the urethra ; c, one of Cowper's glands ; cd,cd, course and orifice of its duct lying
upon the bulb, and passing forward between the spongy body and the urethra, into which
along with its fellow it opens ; c c, one of the corpora cavernosa.
PROSTATIC PORTION— SIXUS POCULARIS. 961
brane, supported by an outer layer of submucous tissue connecting it with
the several parts through which it passes. In the submucous tissue there
are, throughout the whole extent of the urethra, two layers of plain mus-
cular fibres, the innermost disposed longitudinally, and the other in a
circular direction. In accordance with the name or character of those
parts through which it passes, three divisions of the urethra are separately
described as the prostatic, membranous, and spongy portions.
1. The first, or prostatic portion, is the part which passes through the
prostate gland. It is from 12 to 15 lines in length, is the widest part
of the canal, and is larger in the middle than at either end : at the
neck of the bladder its diameter is nearly 4 lines, then it widens a little,
so as to be rather more than 4 lines, arid in old persons 5 or 0, after which
it diminishes like a funnel, until, at its anterior extremity, it is smaller
than at its commencement. It passes through the upper part of the pro-
state, above the middle lobe, so that there is more of the gland below it
than above. Though enclosed in the firm glandular substance, it is more
dilatable than any other part of the urethra ; but immediately at the neck
of the bladder, it is, as elsewhere stated, much more resistant. The trans-
verse section of the urethra, as it lies in the prostate, is widened from side
to Bide and somewhat folded upwards in the middle, the upper and under
surface being in contact.
The lining membrane of the prostatic portion of the urethra is thrown
into longitudinal folds, when no fluid is passing along it ; it forms no proper
valve at the neck of the bladder, unless the elevation named the uvula
vesicse is to be regarded as such. Somewhat in advance of this, and con-
tinued from it along the floor of the passage, projects a narrow median
ridge, about 8 or 9 lines in length, and 1^ line in its greatest height ; this
ridge gradually rises into a peak, and sinks down &gain at its anterior or
lower end, and is formed by an elevation of the mucous membrane and
subjacent tissue. This is the crest of the urethra (crista urethrse), more
generally called c,aput gallinaginis and verumontanum. On each side of this
ridge the surface is slightly depressed, so as to form a longitudinal groove,
named the prostatic sinus, the floor of which is pierced by numerous fora-
mina, the orifices of the prostatic ducts. Through these a viscid fluid oozes
out on pressure ; the ducts of the middle lobe open behind the urethral
crest, and some others open before it.
Sinus pocularis. — At the fore part of the most elevated portion of the
crest, and exactly in the middle line, is a recess, upon or within the margins
of which are placed the slit-like openings of the common seminal or ejacu-
latory ducts, one at each side. This median depression, named sinus
pocularis, vesica prostatica, or utricle, was first described by Morgagni, and
has more lately attracted renewed attention, as corresponding with the
structure which in the female is developed into the uterus.
The utricle forms a cul-de-sac running upwards or backwards, from three
to five lines deep, and usually about one line wide at its entrance and for
some distance up, but acquiring a width of at least two lines at its upper end
or fundus. The prominent walls of the narrow portion form the urethral crest,
and its fundus appears to lie behind and beneath the middle lobe, and
between the two lateral lobes of the prostate. Its parietes, which are dis-
tinct, and tolerably thick, are composed of fibrous tissue and mucous mem-
brane, together with a few muscular fibres, and enclose on each side the ejacu-
latory duct ; numerous small glands open on its inner surface. According to
Kobelt and others, the caput galliiiaginis contains some well-marked erectile
9(52 MALE ORGANS OF GENERATION.
and muscular tissue, and it has been supposed that this eminence, when dis-
tended with blood, may offer an obstacle to the passage of the semen back-
wards into the bladder. (E. H. Weber, Zusatze zur Lehre vom Baue und
Vcrrichtungen der Geschlechts-Organe, 1846 ; Huschke in Scemmerriug's
Anatomie, vol. v. ; Leuckart, " Vesicula Prostutica," in Cyclop, of Anat. &
Phys.)
2. The membranous portion of the urethra comprises the part between
the apex of the prostate, and the bulb of the corpus spongiosum. It mea-
sures three quarters of an inch along its anterior, but only about half an
inch on its posterior surface, in consequence of the projection upwards on it
of the bulb. This is the narrowest division of the urethra. In the middle
its circumference is O'G of an inch ; at the end 0'5. (H. Thompson.) It is
placed beneath the pubic arch, the anterior concave surface being distant
nearly an inch from the bone, leaving an interval, occupied by the dorsal
vessels and nerves of the penis, by areolar tissue, and some muscular fibres.
Its lower convex surface is turned towards the perinseutn, opposite to the
point of meeting of the transverse muscles : it is separated by an interval
from the last part of the rectum. About a line in front of the prostate, it
emerges from between the anterior borders of the levatores ani, and passes
through the deep layer of the subpubic fascia (p. 260) ; it is then placed
between that and the anterior layer or triangular ligament through which
it passes some way farther forwards, but both of these fibrous membranes
are prolonged upon the canal, the one backwards and the other forwards.
Between these two layers the urethra is surrounded by a little erectile tissue,
by some veins, and also by the fibres of the compressor urethrce muscle ;
beneath it, on each side, are Cowper's glands. The proper or plain muscular
fibres of this portion of the urethra are continued over the outer and inner
surfaces of the prostate into the muscular coat of the bladder posteriorly,
and into those of the spongy portion of the urethra anteriorly. (Hancock.)
3. The sponciy portion of the urethra, by far the longest and most vari-
able in length and direction, includes the remainder of the canal, or that
part which is surrounded by the erectile tissue of the corpus spongiosum.
Its length is about six inches. The part contained within the bulb, some-
times distinguished as the bulbous portion, is somewhat dilated ; its circum-
ference being equal to seven-tenths of an inch (Thompson). The succeeding
portion, as far as the glans, is of uniform size, being intermediate in this
respect between the bulbous and membranous portions. The cross section
of its canal appears like a transverse slit. The canal of the urethra situated
in the glans has, on the contrary, when seen in a cross section, the form of
a vertical slit : in this part the canal is again considerably dilated, forming
what is named the fossa navicularis, which is from four to six lines in length,
and is most evident in the form of a depression on the floor of the urethra.
Lastly, at its orifice, which is a vertical fissure from two and a half to
three lines in extent, and bounded by two small lips, the urethra is again
contracted and reaches its narrowest dimensions. In consequence of its
form, and also of the resistant nature of the tissues at its margin, this open-
ing does not admit so large an instrument as even the membranous portion
of the canal.
The mucous membrane of the urethra possesses a lining of stratified
epithelium, of which the superficial cells are columnar, except for a short
distance from the orifice, where they are squamous, and where the subjacent
membrane exhibits papillae.
The whole lining membrane of the urethra is beset with small mucous
COWPEB'S GLANDS— THE SPERMATIC CORD. 963
glands and follicles, commonly named the glands of Littre', the ducts of
which pass obliquely forwards through the membranes. They vary much in
size and in the degree of loculation and ramification of their cavities. Besides
these there are larger recesses or lacunae, opening by oblique orifices turned
forwards or down the canal. These are most abundant along the floor of the
urethra, especially in its bulbous part. One large and conspicuous recess,
situated on the upper surface of the fossa navicularis, is named the lacuna,
magna.
Cowper's Glands. — In the bulbous portion of the urethra, near its anterior
end, are the two openings of the ducts of Cowper's glands. These little
glands themselves are seated farther back than the bulb, beneath the fore
part of the membranous portion of the urethra, between the two layers of the
subpubic fascia, the anterior layer supporting them against the urethra.
The arteries of the bulb pass above, and the transverse fibres of the com-
pressor urethrae beneath these glands. They are two small firm rounded
bodies, about the size of peas, and of a deep yellow colour. They are com-
pound vesicular or racemose glands, composed of several small lobules held
together by a firm investment. This latter, as well as the walls of the ducts,
contains muscular tissue. The branched ducts, which commence in cellular
crypts, unite to form a single excretory duct for each gland, which runs
forwards with its fellow for about an inch or an inch and a half beneath the
mucous membrane, and the two terminate in the floor of the bulbous part of
the urethra by two minute orifices opening obliquely. These glands secrete a
viscid fluid, the use of which is not known ; their existence is said not to
be constant, and they appear to diminish in old age : sometimes there is
only one.
Occasionally there is a third glandular body in front of and between Cowper'a
glands; this has been named the anterior prostate or anti-prostatic gland.
The muscles in connection with the urethra and penis have been already-
described (p. 263).
THE TESTES, AND THEIR EXCRETORY APPARATUS.
The testicles or testes, the two glandular organs which secrete the seminal
fluid, are situated in the scrotum, each being suspended by a collection of
structures termed the spermatic cord.
The spermatic cord. — The parts which enter into this cord are the excre-
tory duct of the testicle, named the vas deferens, the spermatic artery and
veins, lymphatics, nerves, and connecting areolar tissue. Besides this, both
the cord and the testis have several coverings. The structures mentioned
come together to form the cord at the internal or deep abdominal ring
(p. 258), and, extending through the abdominal wall obliquely downwards
and towards the middle line, escape at the superficial or external abdominal
ring (p. 250), whence the cord descends over the front of the pubes into the
scrotum.
COVERINGS OF THE TESTIS AND CORD.
The inguinal canal. — By the term inguinal canal is understood the space
occupied by the spermatic cord as it passes through the abdominal wall. It
extends from the deep to the superficial abdominal ring, and is about an
inch and a half in length. In the upper part of this course, the cord has
placed behind it the fascia trausversalis, and is covered in front by the
lower fibres of the internal oblique and transversalis muscles ; lower down,
3 R 2
964 MALE ORGANS OF GENERATION.
it lies in front of the conjoined tendon of these muscles, the fibres of which
have arched inwards over it, and its creniasteric covering, is in contact
anteriorly with the aponeurosis of the external oblique muscle. The inguinal
canal is therefore said to be bounded posteriorly by the fascia trans versalis
above and the conjoined tendon below, and anteriorly by fibres of the
transversalis and internal oblique muscles above, and the aponeurosis of the
external oblique muscle below ; while its floor is formed by the curving
backwards of Poupart's ligament, and its roof by the apposition of the layers
of the abdominal wall.
As it enters the inguinal canal, the cord receives a covering from the
infundibuliform fascia, a thin layer continuous with the fascia transversalis,
and prolonged down from the margins of the de,jp abdominal ring ; within
the canal it receives a covering from the cremaster muscle and fascia con-
nected with it ; and as it emerges from the canal there is added, superficially
to this, the intercolumnar fascia prolonged from the pillars of the superficial
abdominal ring.
The scrotum. — The scrotum forms a purse-like investment for the testes
and part of the spermatic cords. Its condition is liable to certain variations
according to the state of the health and other circumstances : thus, it is
short and corrugated in robust persons and under the effects of cold, but
becomes loose and pendulous in persons of weak constitution, and under the
relaxing influence of heat. Its surface is marked off into two lateral halves
by a slight median ridge, named the raphe, extending forwards to the
under side of the penis, and backwards along the perinseum to the margin of
the anus.
Within the scrotum, the coverings of the cord and testis, as enumerated
from without inwards, are the skin, superficial fascia and dartos tissue of the
scrotum, the intercolumnar fascia, the cremaster muscle and cremasteric
fascia, and the infundibuliform fascia, which is united to the cord by a
layer of loose areolar tissue ; lastly, the testicle has a special serous tunic,
named the tunica vaginalis, which forms a closed sac, and covers the tunica
albuginea or proper fibrous coat of the gland.
1. The skin in this situation is very thin, and is of a darker colour than
elsewhere ; it is generally thrown into rugse or folds, which are more or less
distinct according to the circumstances already mentioned. It is furnished
with sebaceous follicles, the secretion from which has a peculiar odour, and
it is covered over with thinly scattered crisp and flattened hairs, the
bulbs of which may be seen or felt through the skin when the scrotum is
extended. The superficial blood-vessels are also readily distinguished
through this thin integument.
2. Immediately beneath the skin of the scrotum there is found a thin
layer of a peculiar loose reddish-brown tissue, endowed with contractility, and
named the dartos tunic. This subcutaneous layer is continuous with the super-
ficial fascia of the groin, perinseum, and inner side of the thighs, but acquires
a different structure, and is perfectly free from fat. The dartoid tissue is
more abundant on the fore part of the scrotum than behind, and, moreover,
it forms two distinct sacs, which contain the corresponding testes, and are
united together along the middle line so as to establish a median partition
between the two glands, named the septum scroti, which is adherent below to
the deep surface of the raphe and reaches upwards to the root of the penis.
The dartos is very vascular, and owes its contractile properties to the
presence of a considerable amount of unstriped muscular tissue. Its con-
tractility is slow in its action ; it is excited by the application of cold and of
COVEBIXGS OF THE COED AND TESTIS. 965
mechanical stimuli, but, apparently, not by electricity. By its action the
testes are drawn up or sustained, and at the same time the skin of the
scrotum is more or less corrugated.
3. The intercolumnar or spermatic fascia, a very thin and transparent but
relatively firm layer, derived from the tendon of the external oblique muscle
of the abdomen, is attached above to the margins of the external ring, and
is prolonged downwards upon the cord and testicle. It lies at first beneath
the superficial fascia, but lower down beneath the dartos, and it is inti-
mately connected with the layer next in order.
4. The cremasteric layer is composed of scattered bundles of muscular
tissue, connected together into a continuous covering by intermediate
areolar membrane. The red muscular portion, which is continuous with the
lower border of the internal oblique muscle of the abdomen, constitutes the
cremaster muscle (p. 251), or tunica erythro'ides, and the entire covering is
named the cremasteric fascia.
5. The infundibuliform fascia, continuous above with the fascia transver-
salis arid the subperitoneal areolar membrane, and situated immediately
beneath the cremasteric fascia, invests the cord completely, and is connected
below with the posterior part of the testicle and the outer surface of its
serous tunic.
On forcing air beneath the infundibuliform fascia, a quantity of loose and
delicate areolar tissue is seen to connect its internal or deep surface with the
vas deferens and spermatic blood-vessels, and to form lamellsa between them.
This areolar tissue is continuous above with the subserous areolar tissue
found beneath the peritoneum on the anterior wall of the abdomen ; below,
it is lost upon the back of the testicle. Together with the infundibuliform
fascia just described, it forms the fascia propria of A. Cooper.
Lying amongst this loose areolar tissue, in front of the upper end of
the cord, there is often seen a fibro-areolar band, which is connected
above with the pouch of peritoneum found opposite the upper end of the
inguinal canal, and which reaches downwards for a longer or shorter distance
along the spermatic cord. Occasionally it may be followed as a fine cord,
as far as the upper end of the tunica vaginalis ; sometimes no trace of it
whatever can be detected. It is the vestige of a tubular process of the
peritoneum, which in the fcetus connects the tunica vaginalis with the
general peritoneal membrane. The testicle is placed in the abdomen during
the greater part of foetal life ; but at a period considerably prior to its
escape from the abdominal cavity, a pouch of peritoneum already extends
down into the scrotum. Into this pouch or processus vaginalis peritonei
the testicle projects from behind, supported by a duplicature of the serous
membrane, named the mesorchium. Sooner or later after the gland has
reached the scrotum, the upper part or neck of this pouch becomes
contracted and finally obliterated, from the internal abdominal ring down
nearly to the testicle, leaving no trace but the indistinct fibrous cord already
described, whilst the lower part remains as a closed serous sac, into which
the testicle depends, and which is thenceforth named the tunica vaginalis.
In the female an analogous pouch of peritoneum descends, in the foetus,
for a short distance along the round ligament of the uterus, and has
received the appellation of the canal of Nuck. Traces of it may almost
always be seen in the adult.
The neck of the processus vaginalis sometimes becomes closed at intervals only,
leaving a series of sacculi along the front of the cord ; or a long pouch may continue
open at the upper end, leading from the abdominal cavity into the inguinal canal.
966
MALE ORGANS OF GENERATION.
In other instances, the peritoneal process remains altogether pervious, and the cavity
of the tunica vaginalis is continuous with that of the peritoneum. In such a case of
congenital defect, a portion of intestine or omentum may descend from the abdomen
into the inguinal canal and scrotum, and constitute what is named a congenital hernia.
Lastly, one or both testes may remain permanently within the abdomen, or their
descent may be delayed till after puberty, when it may occasion serious disturbance.
Retention of the testes in the abdomen (cryptorchismus) is, in many instances, the
accompaniment of arrested development of the glandular structure ; it is, however, a
peculiarity which is often present without impotence.
In a few mammals, as the elephant, the testes remain permanently within the
abdomen ; in a much larger number, as the rodentia, they only descend at each period
of rut. The complete closure of the tunica vaginalis is peculiar to man, and may be
considered as connected with his adaptation to the erect posture.
6. The tunica vaginalis. — This tunic forms a shut sac, the opposite walls
of which are in contact with each other. Like the serous membranes in
general, of which it affords one of the simplest examples, it may be described
as consisting of a visceral and a parietal portion. The visceral portion
closely invests the greater part of the body of the testis, as well as the
epididymis, between which parts it recedes in the form of a pouch (digital
fossa), and lines their contiguous surfaces, and it adheres intimately to the
Fig. 675.
Pi*. 675.— THE LEFT TUNICA
VAGINALTS OPENED. SHOW-
ING THE TESTIS, EPII>IDY-
MIS, &c.
p, p, the cut edges of the
parietal tunica vagiaalis drawn
aside laterally, as well as above
and^ below ; t, the body of the
testicle ; e, the globus major
of the epididymis ; e', the
globus minor, near which, /, a
fold of the tunica vaginalis (or
ligament) passes from the
body of the testis to the side ;
in the upper part of the figure
the tunica vaginalis has been
slightly dissected off at the
place of its reflection on the
cord to show vd, the vas
deferens, and g, the organ of
Giraldes; G, the three small
nodules of this organ enlarged
about ten times, and showing
the remains of tubular struc-
ture within them.
proper fibrous tunic of
the gland. Along the pos-
terior border of the gland,
where the vessels and
ducts enter or pass out, the
serous coat, having been
reflected, is wanting.
The parietal or scrotal portion of the tunica vaginalis is more extensive
than that which covers the body of the testis ; it reaches upwards, some-
times for a considerable distance, upon the spermatic cord, extending some-
what higher on the inner than on the outer side. It also reaches downwards
THE TESTES— FORM AND SITUATION. 967
below the testicle, which, therefore, appears to be suspended at the back of
the serous sac, when this latter is distended with fluid.
VESSELS AND NERVES OF THE COVERINGS OF THE TESTIS AND CORD.
The arteries are derived from several sources. Thus, the two external
pudic arteries (p. 437), branches of the femoral, reach the front and sides of
the scrotum, supplying the integument and dartos ; the superficial perinea!
branch of the internal pudic artery (p. 426) is distributed to the back part of
the scrotum ; and, lastly, more deeply seated than either of these, is a branch
given from the epigastric artery, named cremasteric, because it is chiefly
distributed to the cremaster muscle ; it also supplies small branches to
the other coverings of the cord, and its ultimate divisions anastomose with
those of the other vessels. The veins, which, owing to the thinness of the
integuments, are apparent on the surface of the scrotum, follow the course
of the arteries. The lymphatics pass into the inguiual lymphatic glands.
The nerves also proceed from various sources. Thus, the ilio-inguinal, a
branch of the lumbar plexus (p. 660), comes forwards through the external
abdominal ring, and supplies the integuments of the scrotum ; this nerve is
joined also by a filament from the ilio-hypogastric branch of the same
plexus : sometimes two separate cutaneous nerves come forward through
the external ring. The two superficial perineal branches of the internal
pudic nerve accompany the artery of the same nerve and supply the inferior
and posterior parts of the scrotum. The inferior pudendal, a branch of the
small sciatic nerve (p. 675), joins with the perineal nerves, and is distributed
to the sides and fore part of the scrotum. Lastly, the branch of a deeper
nerve, springing from the lumbar plexus, and named genito-crural (p. 661),
conies into contact with the spermatic cord at the internal abdominal ring,
passes with it through the inguinal canal, and supplies the fibres of the
cremaster, besides sending a few filaments to the other deep coverings of
the cord and testicle.
THE TESTES.
The testes are suspended obliquely in the scrotum by means of the cord
and membranes already described : they are usually placed at unequal
heights, that of the left side being lower than the other. They are of an
oval form, but are slightly compressed laterally, so that they have two some-
what flattened sides or faces, an upper and a lower end, an anterior and a pos-
terior border. They are from an inch and a half to two inches long, about
an inch and a quarter from the anterior to the posterior border, and nearly
an inch from side to side. The weight of each varies from three-quarters
of an ounce to an ounce, and the left is often a little the larger of the two.
The front and sides of the testicle, together with the upper and the lower
ends, are free, smooth, and closely invested by the tunica vaginalis. The pos-
terior border, however, is attached to the spermatic cord, and it is here that
the vessels and nerves enter or pass out. When the testis is suspended in its
usual position, its upper end is directed obliquely forwards and outwards,
as well as upwards, whilst the lower, which is rather smaller, has the oppo-
site direction. It follows from this that the posterior or attached border is
turned upwards and inwards, and the outer flattened face slightly backwards.
Along the outer edge of the posterior border of the gland, and resting
also on the neighbouring portion of its outer face, is placed a long narrow
body, the epididymis, which forms part of the excretory apparatus of the
968 MALE ORGANS OF GENERATION.
testicle, and is principally composed of the convolutions of a long tortuous
canal or efferent duct, to be presently described. Its upper extremity,
which is enlarged and obtuse, projecting forwards on the upper end of the
test is, is named the head of the epididymis, or globus major ; the lower,
which is more pointed, is termed the tail, or globus minor ; whilst the inter-
vening and narrower portion is named the body. The outer convex surface
of the epididymis and the thin anterior border are free, and covered by the
tunica vaginalis. The inner surface, except at the upper and lower ends,
is also free, and invested by the same tunic, which here forms the digital
pouch between the epididymis and the outer face of the testicle, and nearly
surrounds the epdidymis, except along its posterior border, which is held
to the gland by a duplicature of the serous membrane, containing numerous
blood-vessels. At its upper and lower extremity, the inner surface of the
epididymis is attached to the testicle, — the lower end, or globus minor, by
fibrous tissue and a reflection of the tunica vaginalis, the globus major also
by the efferent ducts of the testicle.
At the back of the testis and epididymis, beneath the fascia propria, there
is found, opposite the lower two-thirds of the testis, a considerable amount
of unstriped muscular tissue, the inner muscular tunic of Kolliker.
Situated on the front of the globus major, somewhat to the outer side,
there are found in the majority of cases one or more short processes of the
tunica vaginalis, containing fine blood-vessels. They are called corpora
Morgagni, or hydatids of Morgagni ; that anatomist having been the first
to describe them. One of these, more dilated than the rest, and pyriform
in shape, lies closely between the head of the epididymis and the testicle,
and appears to be the remains of the foetal structure, termed Mullet's duct :
they are without any known physiological importance.
The testis proper, exclusive of the epididymis, is enclosed in a strong
capsule, the tunica albuginea. This is a dense unyielding fibrous membrane,
of a white colour, and about half a line thick, which immediately invests
the soft substance of the testicle, and preserves the form of the gland. It
is composed of bundles of fibrous tissue, which interlace in every direc-
Flg. 676. Fig. 676. — TRANSVERSE SECTION THROUGH THE RIGHT
TESTICLE AND THE TUNICA VAGINALIS (from Kol-
liker).
a, connective tissue enveloping the parietal layer of
the tunica vaginalis ; 6, this layer itself ; c, cavity of
the tunica vaginalis ; d, reflected or visceral layer
adhering to e, the tunica albuginea ; /, covering of
epididymis (g) on the right or outer side ; h, medias-
tinum testis ; «, branches of the spermatic artery ; Ic,
spermatic vein ; I, vas deferens ; m, small artery of
the vas deferens ; n, lobules of the testis ; o, septa or
processes from the mediastinum to the surface.
tion. The surface is for the most part covered
by the tunica vaginalis, except along the pos-
terior border of the testicle, where the sper-
matic vessels pass through, and except also at
the parts to which the two extremities of the epididymis are attached.
Viewed from the interior, the fibrous tissue of the tunica albuginea is seen
to be prolonged forwards, at the posterior and upper border of the testis, for
a few lines into the substance of the gland, so as to form within it an
incomplete vertical septum, known as the corpus Highmorianum, and named
GLANDULAR SUBSTANCE OF THE TESTIS. 969
by Astley Cooper mediastinum testis. Projecting inwards from the back
of the testis, it extends from the upper nearly to the lower end of the
gland, and it is wider above than below. The firm tissue of which it is
composed is traversed by a network of seminal ducts, and by the larger
blood-vessels of the gland, which are lodged in channels formed in the
fibrous tissue.
From the front and sides of the corpus Highmorianum numerous slender
fibrous cords and imperfect septa of connective tissue are given off in radiating
directions, and are attached by their outer ends to the internal surface of
the tunica albuginea at different points, so as to assist in maintaining the
general shape of the testicle, and enclose the several lobes into which the
substance of the testis is divided. The whole internal surface of the tunica
albugiuea is covered by a multitude of fine blood-vessels, which are branches
of the spermatic artery and veins, and are held together by a delicate
areolar web. Similar delicate ramifications of vessels are seen on the
various fibrous offsets of the mediastinum, upon which the blood-vessels are
thus supported in the interior of the gland. This vascular network,
together with its connecting areolar tissue, constitutes the tunica vasculosa
of Astley Cooper.
The proper glandular substance of the testicle is a soft but consistent mass
of a reddish-yellow colour, which is divided into numerous small lobes of
conical form, with the larger ends turned towards the surface of the testicle,
and the smaller towards the mediastinum. The number of these lobes (lobuli
testis) has been estimated at 250 by Berres, and at upwards of 400 by Krause.
They differ iu size according to their position, those which occupy the middle
of the gland and reach its anterior border being longer and larger than the
rest. They consist almost entirely of small convoluted tubes, named tubuli
seminiferi, vascula serpentina, in the interior of which the seminal fluid is
secreted. Each lobe contains one, two, three, or even more of these con-
Fig. 677. — PLAN OP A VERTICAL SECTION OP THE TESTICLE, Fig. 677.
SHOWING THE ARRANGEMENT OP THE DlJCTS.
The true length and diameter of the ducts have been dis-
regarded, a, a, tubuli senainiferi coiled up in the separate
lobes ; b, vasa recta ; c, rete vasculosum ; dt vasa efferentia
ending in the coni vasculosi ; I, e, g, convoluted canal of the
epididymis ; h, vas deferens ; f, section of the back part of
the tunica albuginea ; i, i, fibrous processes running between
the lobes ; s, mediastinum.
voluted tubules, the coils of which, being but loosely
held together, may be more or less successfully un-
ravelled by careful dissection under water. Lauth
estimates their mean number to be 840, and the
average length two feet and a quarter. Their dia-
meter, which is uniform throughout their whole
course, is from ^-J-^th to yj0th of an inch. They
present two kinds of convolutions, each tube having
a fine and regular undulation, which gives a granular appearance to the
whole mass, and this undulating tube being again thrown into com-
plicated folds, which are compressed so as to be elongated iu the direction
of the lobule. The lobules are never quite distinct, for here and there
tubules are always to be found passing from each to those around ; and it
sometimes happens that tubules which are divided by a straight plane of
970 MALE ORGANS OF GENERATION.
contact at ono part, are intimately connected at another ; so that the
division of the mass into lobules varies greatly in its extent, and hence the
different estimates of the number of the lobules by different anatomists.
The walls of the tubuli seminiferi are composed of connective tissue, lined
with a basement membrane, and sometimes presenting an epithelium, com-
posed of nucleated granular corpuscles, but, in the period of activity,
filled with cells of different sizes, without regular arrangement or any lumen
in the interior. lu aged subjects there is much fatty matter accumulated
in these cells, so that the tubes acquire a yellower colour than in early life.
The walls of the tubes are sufficiently strong to bear the forcible injection of
mercury, which has been commonly employed for their investigation.
The mode in which the tubes commence appears to be twofold — viz., by
free closed extremities, hid within the lobules, but more frequently by ana-
stomotic arches or loops. After an exceedingly tortuous course, they at
length, in approaching the corpus Highmorianum, lose in a great measure
the convoluted disposition, becoming at first slightly flexuous and then
nearly straight. The separate tubuli of each lobe, and then those of adjoin-
ing lobes, unite together into larger tubes, which enter the fibrous tissue of
the mediastinum and, being placed amongst the branches of the blood-vessels,
form the next order of the seminal ducts.
These, which, from their comparatively straight course, are named tubuli
recti or vasa recta, are upwards of twenty in number, and are from -^th to
7J0th of an inch in diameter. They pass upwards and backwards through
the fibrous tissue, as already stated, and end in a close network of tubes,
named by Haller the rete vasculosum testis, which lies in the substance of the
corpus Highmorianum, along the back part of the testicle, but in front of
the primary subdivisions of the spermatic blood-vessels before these enter
the gland. The tubes composing the rete have very thin walls. According
to Kolliker, indeed, they have none, but are mere
Fig. 678. channels in the fibrous membrane, lined with squamous
, epithelium. They conduct the secretion to the upper
IJ end of the testis, where they open into the vasa
efferentia.
Fig. 678.— DUCTS OF THE TESTICLE INJECTED WITH MERCURY
(from Haller).
a, body of the testicle ; 6, tubuli in the interior of the gland ;
c, rete vasculosum ; d, vasa efferentia terminating in the coni-
vasculosi; e, /, g, convoluted canal of the epididymis ; k, vas
deferens ascending from the globus minor of the epididymis.
The vasa efferentia are from twelve to fifteen, or
sometimes twenty in number; they perforate the tunica
albuginea at the upper end of the posterior border of
the testicle, beneath the globus major of the epididy-
mis, of which they may be said to form a part, and
in the convoluted canal of which they ultimately
terminate. On emerging from the testis, these vasa
efierentia are straight, but, becoming more and more convoluted as they
proceed towards the epididymis, they form a series of small conical masses,
the bases of which are turned in the same direction, and which are named
com vasculosi. Their walls contain, besides fibrous tissue, longitudinal and
transverse muscular fibres. The largest of the cones is about eight lines
EPIDIDYMIS— VAS DEFEKEXS.
971
long, and when unrolled, each is found to consist of a single coiled duct,
varying from six to eight inches in length, and the diameter of which
gradually decreases from the testis to the epididymis (Huschke). Opposite
the globus major these separate efferent vessels open, at intervals which in
the unravelled tube are found to be about three inches in length, into a
single caual or duct, the intervening and subsequent convolutions of which
constitute the epididymis itself.
Fig. 679.— INJECTED TESTICLE, Fig. 679.
EPIDIDYMIS, AND VAS DEFERENS
(from Kolliker after Arnold).
a, body of the testicle ; 6, lo-
bules ; c, vasa recta ; d, rete vas-
culosum ; et vasa efferentia ; /,
coni vasculosi ; g, epididymis ; A,
vas deferens ; z, vas aberrans ; m,
branches of the spermatic artery
passing to the testicle and epidi-
dymis ; n, ramification in the
testis ; o, deferential artery ; p,
its union with a twig of the sper-
matic artery.
The canal of the epididy-
mis is disposed in very nu-
merous coils, and extends
from the globus major down-
wards to the globus minor or
tail, where, turning upwards,
it is continued on as the vas
deferens. When its com-
plicated flexuosities are un-
rolled, it is found to be
twenty feet and upwards in
length. The smallest wind-
ings are supported and- held
together by fine areolar
tissue ; but, besides this, numerous fibrous partitions are interposed
between larger masses of the coils, which have been named the lobes of
the epididymis, the general direction of which is across that body. The
canal of the epididymis is, at its commencement, about -^th of an inch
in diameter, but diminishing as it proceeds towards the globus minor, it is
about -g^th of an inch, after which it again increases in size, and becomes
less tortuous as it approaches the vas deferens. Its coats, which are at first
very thin, become thicker in its progress.
The vasa efferentia and the tube of the epididymis differ from the other
portions of the ducts of the testis in their epithelium being ciliated. In the
epididymis the cells are greatly elongated, in the vasa efferentia they are
shorter ; in the lower part of the epididymis the cilia disappear (Becker,
corroborated in the human subject, by Kolliker).
VAS DEFERENS.
The vas deferens, or excretory duct of the testis, is a hard round tube,
which forms the continuation upwards of the convoluted canal of the epi-
didymis. It commences at the lower end of the epididymis, and, at first
972 MALE ORGANS OF GENERATION.
rather tortuous, but afterwards becoming straight, it ascends upon the inner
side of the epididymis, aud along the back of the testicle, separated from
both, however, by the blood-vessels passing to and from the gland. Continu-
ing, then, to ascend in the spermatic cord, the vas deferens accompanies
the spermatic artery, veins and nerves, as far as the internal abdominal
ring. Between the testicle and the external ring its course is vertical : it
lies behind the spermatic vessels, and is readily distinguished by its hard
cord-like feel. Having passed obliquely upwards and outwards along the
inguinal canal, and reached the inner border of the internal abdominal ring,
it leaves the spermatic vessels (which extend to the lumbar region), and turns
suddenly downwards and inwards into the pelvis, crossing over the external
iliac vessels, and turning round the outer or iliac side of the epigastric
artery. Running beneath the peritoneum, it reaches the side of the bladder,
curves backwards and downwards to the under surface of that viscus, and
then runs forwards to the base of the prostate gland. In its course within
the pelvis, it crosses over the cord of the obliterated hypogastric artery, and
to the inner side of the ureter. Beyond this point, where it ceases to be
covered by the peritoneum, it is found attached to the coats of the bladder,
in contact with the rectum, and gradually approaches its fellow of the oppo-
site side. Upon the base of the bladder, the two vasa deferentia are situated
between two elongated receptacles, named the seminal vesicles ; and, close
to the base of the prostate, each vas deferens ends by joining with the duct
from the corresponding seminal vesicle, which is placed on its outer side to
form one of the two common seminal or ejaculatory ducts.
The vas deferens measures nearly two feet in length. In the greater part
of its extent it is cylindrical or slightly composed, and has an average diameter
of about one line and a quarter ; but towards its termination, beneath the
bladder, it becomes enlarged and sacculated, approaching thus in character
to the seminal vesicle. Previously to its junction with the duct of that vesicle,
it again becomes narrowed to a fine cylindrical canal. The walls of the vas
deferens are very dense and strong, measuring one-third of a line in
thickness ; whilst, on the other hand, the canal is comparatively fine, its
diameter being only from one-fourth to one-half a line. In the sacculated
portion the passage is much wider, and the walls are thinner in proportion.
Besides an external areolar investment, and an internal lining mucous
membrane, the vas defereus is provided with an intermediate thick tunic,
which is dense in structure, some what elastic, and of a deep yellowish colour.
This coat consists principally of longitudinal muscular fibres, mixed with
some circular ones. Huschke describes two longitudinal layers with in-
termediate circular fibres. The external and middle layers are thick and
strong ; but the internal longitudinal stratum is extremely thin, constituting
not more than -^th of the muscular coat. The vasa deferentia of the
dog, cat, and rabbit were found by E. Weber to exhibit lively peristaltic
contractions when stimulated by means of electricity.
The surface of the mucous membrane is pale ; it is thrown into three
or four fine longitudinal ridges, and, besides this, in the sacculated portion of
the duct, is marked by numerous finer rugae which enclose irregular poly-
hedral spaces, resembling in this the lining membrane of the vesiculaa semi-
nales. The epithelium is of the columnar kind, not ciliated.
Vas aberrans. — This name was applied by Haller to a long narrow tube,
or diverticulum, discovered by him, and almost invariably met with, which
leads off from the lower part of the canal of the epididymis, or from the
commencement of the vas deferens, and extends upwards in a tortuous
SEMINAL VESICLES AXD EJACULATORY DUCTS. 973
manner for one or two inches amongst the vessels of the spermatic cord,
where it ends by a closed extremity. Its length, when it is unravelled,
ranges from one inch and a half to fourteen inches ; and its breadth increases
towards its blind extremity. Sometimes this diverticulum is branched,
and occasionally there are two or more such aberrant ducts. Its structure
appears to be similar to that of the vas deferens. Its origin is probably
connected with the Wolffian body of the foetus, but the exact mode of its
formation and its office are unknown. Luschka states that occasionally it
does not communicate with the canal of the epididymis, but appears to be a
simple serous cyst.
Organ of Giraldes. — This is a minute structure situated in the front of
the cord, and in contact with the caput epididymis. It consists usually of
several small irregular masses containing convoluted tubules lined with
squamous epithelium, and is scarcely to be recognised until the surrounding
connective tissue has been rendered transparent by reagents. Its tubules
appear to be persistent elements of the Wolffian body. (Giraldes, in Bulletin
de la Soc. Anat. de Paris, 1857, and in Journal de la Physiologie, 1861.)
THE SEMINAL VESICLES AND EJACULATORY DUCTS.
The vesiculce. seminales are two membranous receptacles, situated, one on
each side, upon the base of the bladder, between it and the rectum. When
distended, they form two long-shaped sacculated bodies, somewhat flattened
above, where they are firmly attached to the bladder, but convex below ;
they are widened behind and narrow in front. Their length is usually about
two inches and a half, and their greatest breadth from four to six lines ; but
they vary in size in different individuals, and also on opposite sides of the
same subject.
Their posterior obtuse
extremities are separated
widely from each other, but
anteriorly they converge so
as to approach the two <<
vasa defereutia, which run
Fig. 680.— DISSECTION OF THE Jg
BASE OP THE BLADDER AND JH§
PROSTATE GLAND, SHOWING THE
VESICULA: SEMINALES AND VASA
DEFERENTIA (from Haller).
a', lower surface of the bladder
at the place of reflection of the
peritoneum ; 6, the part ahove
covered by the peritoneum ; i,
left vas deferens, ending in e,
the ejaculatory duct ; s, left
vesicula seminalis joining the
same duct ; s, s, tbe right vas
deferens and right vesicula semi-
nalis, which has been unravelled ;
p, under side of the prostate
gland ; m, part of the urethra ;
u, M, tbe ureters, the right one
turned aside.
forwards to the prostate between them. The small triangular portion
of the base of the bladder, which is marked off by the two vesiculse semi-
974 MALE ORGANS OF GENERATION.
nales at the sides with the vasa deferentia interposed, and behind by the
Hue of reflexion of the peritoneum from the bladder to the rectum, rests
mmediately on that intestine. The seminal vesicles themselves are also
supported by the sides of the rectum, but they are separated from the
bowel by a layer of the recto- vesical fascia, which holds them to the base of
the bladder.
The sacculated appearance of the vesiculee seminales is owing to their
peculiar formation. Each consists of a tube somewhat coiled and repeat-
edly doubled on itself, and firmly held in that condition by a dense fibrous
tissue. When unrolled, this tube is found to be from four to six inches long,
and about the width of a quill. Its posterior extremity is closed, so that it
forms a long cul-de-sac ; but there are generally, if not always, several
longer or shorter branches or diverticula developed from it, which also end
by closed extremities. Its anterior extremity, which forms the fore part of
the vesicula, becomes straight and narrowed, and ends opposite the base
of the prostate by uniting on its inner side, at a very acute angle, with the
narrow termination of the corresponding vas defereus to form a single canal,
which is the common seminal or ejaculatory duct.
In structure, the vesiculse seminales resemble very closely the adjoining
sacculated portions of the vasa deferentia. Besides an external fibro-areolar
investment, connected with the recto-vesical fascia, they have a proper coat,
which is firm, dense, and somewhat elastic, and consists of rigid white
fibres and of others of a deep yellowish-brown hue. Muscular tissue is
found in their walls, at least on the posterior aspect, where longitudinal
and transverse bands pass over them from the muscular wall of the bladder
(Ellis and Kolliker). The mucous membrane is pale, or has a dirty
brownish-white colour. It is traversed by multitudes of fine rugae, which
form an areolar structure resembling that seen in the gall-bladder, but deeper
and composed of much finer meshes. The epithelium of the vesiculse is of the
squamous kind ; its particles have a granular character.
The seminal vesicles serve as receptacles or reservoirs for the semen, as is
easily proved by a microscopic examination of their contents ; but, besides
this, it is supposed by some that they secrete a peculiar fluid which is incor-
porated with the semen.
The common seminal or ejaculatory ducts, two in number, are formed on
each side by the junction of the narrowed extremities of the corresponding
vas defereus and vesicula seminalis, close to the base of the prostate gland.
From this point they run forwards and upwards, at the same time approach-
ing each other, and then pass side by side through the prostate between its
middle and two lateral lobes. After a course of nearly an inch, during
which they become gradually narrower, they end in the floor of the prostatic
portion of the urethra by two small slit-like orifices placed one on each
prominent margin of the verumontanum close to the opening of the sinus
pocularis. For a short distance the ejaculatory ducts run in the substance
of the walls of this sinus.
The coats of the common seminal duct, as compared with those of the
vas deferens and vesicula, are very thin. The strong outer tunic almost
entirely disappears after the entrance of the ducts between the lobes of the
prostate, but muscular fibres may be traced into the prostatic portion ; and
the mucous membrane becomes gradually smoother, and at length passes
into that of the urethra. The muscular fibres of the duct, according to
Heule, are separated in the prostate to form the trabeculee of a layer of
cavernous tissue.
VESSELS AXD NERVES OF THE TESTIS. 975
These ejaculatory ducts serve to convey the fluid contained in the seminal
vesicles and vasa defereutia into the urethra.
VESSELS AND NERVES OF THE TESTIS.
The testicle and its excretory apparatus receive blood-vessels and nerves
from different sources from those which supply the coverings of those parts.
The spermatic artery, or proper artery of the testicle (p. 414), is a slender
and remarkably long branch, which arises from the abdominal aorta, and
passing down the posterior abdominal wall reaches the spermatic cord, and
descends along it to the gland. In early foetal life its course is much shorter,
as the testis is then situated near the part of the aorta from which the artery
arises. As the ves-el approaches the testicle, it gives off small branches to the
epididymis, and then divides into others which perforate the tunica albuginea
at the back of the gland, and pass through the corpus Highmorianum ; some
spread out on the internal surface of the tunica albuginea, whilst others run
along between the lobes of the testis, supported by the fibrous processes of
the mediastinum. The smallest branches ramify on the delicate membranous
septa between the lobes, before supplying the seminiferous tubes.
The vas deferens receives from the superior vesical artery a long slender
branch which accompanies the duct, and is hence named the deferent artery
or artery of the vas deferens (p. 421). It ramifies on the coats of the duct, and
reaches as far as the testis, where it anastomoses with the spermatic artery.
The spermatic veins (p. 473) commence in the testis and epididymis, pass out
at the posterior border of both, and unite into larger vessels, which freely com-
municate with each other as they ascend along the cord, and form a plexus,
named the pampiniform plexus. Ultimately two or three veins follow the
course of the spermatic artery into the abdomen, where they unite into a
single trunk, that of the right side opening into the vena cava, and that of
the left into the left renal vein.
The lymphatics (p. 495) accompany the spermatic vessels and terminate in
the lumbar lymphatic glands, which lie about the large blood-vessels in
front of the vertebral column. According to Ludwig and Tomsa, they begin
in a large network of spaces which completely fills the intervals between the
tubuli seminiferi. According to Henle, these intervals are occupied by
granular matter, which he compares with the contents of nerve-cells, and
which abounds in rounded nuclei. (Ludwig and Tomsa, in Sitzungsberichte
d. Kaiserl. Akad. Vienna, 1862.)
The nerves are derived from the sympathetic system. The spermatic
plexus (p. 701) is a very delicate set of nervous filaments, which descend
upon the spermatic artery from the aortic plexus. Some additional fila-
ments, which are very minute, come from the hypogastric plexus, and
accompany the artery of the vas deferent.
The vesiculse seminales receive branches from the inferior vesical and middle
hsemorrhoidal arteries. The veins and lymphatics correspond. The nerves
belong to the sympathetic system, and come from the hypogastric plexus.
The semen is a thick whitish fluid, which consists of a liquor seminis, and of certain
solid particles. It is the combined product of the testes and accessory generative
glands, the former secreting spermatozoa, and little more fluid than is necessary to
convey these ; the latter diluting this secretion with additional fluid.
The liquor seminis is colourless, transparent, and of an albuminous nature. It con-
tains floating in it, besides squamous and columnar epithelium cells, oil-like globules
and minute granular matter, seminal granules (Wagaer), and the spermatozoa or
spermatic filaments.
976
MALE ORGANS OF GENERATION.
The seminal granules are rounded colourless corpuscles, having a granular aspect.
They average about ^^ th of an inch in diameter, and may be allied to mucus-
corpuscles.
Fig. 681.
A. B.
Fig. 681 A. — SPERMATIC FILAMENTS FROM TIIK
HUMAN VAS DEFERENS (from Kolliker).
1, magnified 350 diameters ; 2, magnified 800
diameters ; a, from the side ; b, from above.
Fig. 681 B. — SPERMATIC CELLS AND SPERMA-
TOZOA OP THE BULL UNDERGOING DEVELOPMENT
(from Kolliker). ^
1, spermatic cells with one or two nuclei, one
of them clear ; 2, 3, free nuclei with spermatic
filaments forming ; 4, the filaments elongated
and the body widened ; 5, filaments nearly fully
developed.
Fig. 681 C. — ESCAPE OF THE SPERMATOZOA FROM
THEIR CELLS IN THE SAME ANIMAL.
1, spermatic cell containing the spermatozoon
coiled up within it ; 2, the cells elongated by the
partial uncoiling of the spermatic filament ; 3,
a cell from which the filament has in part become
free ; 4, the same with the body also partially
free ; 5, spermatozoon from the epididymis with
vestiges of the cell adherent ; 6, spermatozoon
from the vas deferens, showing the small enlarge-
ment, b, on the filament.
The spermatozoa are peculiar particles, which, during life and for some hours after
being removed from the testicle, perform rapid vibratory or lashing movements. Each
consists of a flattened oval part or so-called body, and of a long slender filiform tail.
The body is about ^Vo^ °f an mc^ ^n wi(ltn> and the entire spermatozoon is from
r7J-flth to 4o0th of an inch in length. The body often contains a minute spot, and, at
its junction with the narrow filament or tail, there is frequently a slight projecting
fringe or collar. The spermatozoa are developed like nuclei in the interior of the
spermatic cells, the cells subsequently becoming enlarged into transparent vesicular
bodies of considerable size, in which one or several spermatozoa may be seen. Some-
times a group of cells, each containing a single spermatozoon, is seen enclosed within a
parent cell. The spermatozoa are not normally found free until they reach the rete testi*.
(Wagner and Leuckart, Article "Semen " in Cyclop, of Anat. and Phys. ; Kolliker
in Handbuch).
FEMALE ORGANS OF GENERATION— THE VULVA. 977
ORGANS OF GENERATION" IN THE FEMALE.
The generative organs in the female consist of the ovaries, uterus, and
Fallopian tubes, which are named the internal, and the vagina and vulva,
named the external organs of generation.
THE VULVA.
The vulva, or pudendum, is a general term, which includes all the parts
perceptible externally, viz., the rnons Veneris, the labia, the hymen or
caruncul*? , the clitoris, and the nyinphse. The urethra also may be described
in connection with these parts.
The integument on the fore part of the pubic symphysis, elevated by a
quantity of areolar and adipose substance deposited beneath it, and covered
with hair, is termed the mons Veneris. The labia pudendi (labia externa
v. majora) extend downwards and backwards from the mous, gradually be-
coming thinner as they descend. They form two rounded folds of integu-
ment so placed as to leave an elliptic interval (rimd) between them, the
outer surface of each being continuous with the skin, and covered with
scattered hairs, whilst the inner is lined by the commencement of the
geni to-urinary mucous membrane. Between the skin and mucous mem-
brane there is found, besides fat, vessels, nerves, and glands, some tissue
resembling that of the dartos in the scrotum of the male. The labia majora
unite beneath the mons and also in front of the perineum, the two points
of union being called commissures. The posterior or inferior commissure is
about an inch distant from the margin of the anus, and this interval is
named the perineum. Immediately within the posterior commissure, the
labia are connected by a slight transverse fold (frcenulum pudendi), which
has also received the name of fourchette, and is frequently torn in the first
parturition. The space between it and the commissure has been called
fossa navicularis.
Beneath the anterior commissure, and concealed between the labia, is the
clitoris, a small elongated body corresponding in conformation and structure
to a diminutive penis, but differing in having no corpus spongiosum nor
urethra connected with it below. It consists of two corpora cavernosa, which
are attached by crura to the rami of the ischium and pubes, and are united
together by their flattened inner surfaces which form an incomplete pectini-
form septum. The body of the clitoris, which is about an inch and a half
long, but is hidden beneath the mucous membrane, is surmounted by a
small glans, consisting of spongy erectile tissue. The glans is imperforate,
but highly sensitive, and covered with a membranous fold, analogous to the
prepuce. There is a small suspensory ligament, like that of the penis ; and
the two ischio-cavernous muscle?, named in the female erectores clitoridis,
have the same connections as in the male, being inserted into the crura of
the corpora cavern osa.
From the glans and preputial covering of the clitoris two narrow pendu-
lous folds of mucous membrane pass backwards for about an inch and a
half, one on each side of the entrance to the vagina. These are the nymphce
(labia interna v. miuora). Their inner surface is continuous with that of
the vagina ; the external insensibly passes into that of the labia majora.
They contain vessels between the laminae of tegurnentary membrane, but,
according to Kobelt, no erectile plexus ; indeed, they would seem to corre-
spond to the cutaneous covering of the male urethra (supposed to be split
3 s
978
FEMALE ORGANS OF GENERATION.
open), whilst the erectile structure corresponding to the bulb and spongy
body (in two separate right and left halves) lies deeper, as will be presently
explained. (Kobelt, Die mannlichen und weiblichen Wollustorgaue, 1844.)
Fig. 681.*
Fig. 681.*— LATERAL VIEW OP THE EREC-
TILE STRUCTURES OP THE EXTERNAL
ORGANS IN THE FEMALE (from Kobelt). f
The blood-vessels have been injected,
and the skin and mucous membrane have
been removed ; a, bulbus vestibuli ; c,
plexus of veins named pars intermedia ; e,
glans clitoridis ; f, body of the clitoris ; It,
dorsal vein ; I, right crus clitoridis ; m,
vestibule ; n, right gland of Bartholin.
Between the nymphse is the
angular interval called the vestibule,
in which is situated the circular
orifice of the urethra, or meatvs
tirinarius, about an inch below the
clitoris and just above the entrance
to the vagina. The membrane which
surrounds this orifice is rather pro-
minent in most instances, so as
readily to indicate its situation.
Immediately below the orifice of the urethra is the entrance to the vagina,
which, in the virgin, is usually more or less narrowed by the hymen. This
is a thin duplicature of the mucous membrane, placed at the entrance to
the vagina ; its form varies very considerably in different persons, but is
most frequently semilunar, the concave margin being directed forwards
towards the pubes. Sometimes it is circular, and is perforated only by a
small round orifice, placed usually a little above the centre ; and occa-
sionally it is cribriform, or pierced with several small apertures ; and it may
in rare instances completely close the vagina, constituting " imperforate
hymen." On the other hand, it is often reduced to a mere fringe, or it
may be entirely absent. After its rupture, some small rounded elevations
remain, called carunculce myrtiformes.
The mucous membrane may be traced inwards from the borders of the
labia majora, where it is continuous with the skin : it forms a fold over the
vascular tissue of the nymphse, and is then prolonged into the urethra and
vagina. It is smooth, reddish in colour, is covered by a scaly epithelium,
and is provided with a considerable number of mucous crypts and follicles
and with glands which secrete an unctuous and odorous substance. The
mucous crypts and follicles are especially distinct on the inner surface of
the nymphse, and near the orifice of the urethra. The sebaceous glands
are found beneath the prepuce, and upon the labia majora and outer surface
of the nymphee.
The glands of Bartholin (or of Duverney), corresponding to Cowper's
glands in the male, are two reddish yellow round or oval bodies, about
the size of a large pea or small beau, lodged one on each side of the
commencement of the vagina, between it and the erectores clitoridis
muscles, beneath the superficial perineal fascia, and in front of the trans-
verse muscles. Their ducts, which are long and single, run forward and
ERECTIIE TISSUES OF THE VFLYA. 979
open on the inner aspect of the nymphse, outside the hymen or carunculse
ruyrtiformes.
Erectile tissue. — All the parts of the vulva are supplied abundantly with
blood-vessels, and in certain situations there are masses composed of venous
plexuses, or erectile tissue, corresponding to those found in the male.
Besides the corpora cavernosa and glans clitoridis, already referred to, there
Fig. 682.
Fig. 632. — FRONT VIEW OP THE ERECTILE STRUCTURES OP THE EXTERNAL ORGANS IN
THE FEMALE (from Kobelt). f
a, bulbus vestibuli ; b, sphincter vaginee muscle ; e, e, venous plexus or pars inter-
media ; /, glans clitoridis ; g, connecting veins ; A, dorsal vein of the clitoris ; k, veins
passing beneath the pubes ; I, the obturator vein.
are two large leech-shaped masses, the bulbi vestibidi, about an inch long,
consisting of a network of veins, enclosed in a fibrous membrane, and lying
one on each side of the vestibule, a little behind the nymphse. They are
rather pointed at their upper extremities, and rounded below : they are sus-
pended, as it were, to the crura of the clitoris and the rami of the pubes,
covered internally by the mucous membrane, and embraced on the outer side
by the fibres of the constrictor vaginse muscle. They are together equi-
valent to the bulb of the urethra in the male, which, it will be remembered,
presents traces of a median division. In front of the bipartite bulb of the
vestibule is a smaller plexus on each side, the vessels of which are directly
continuous with those of the bulbus vestibuli behind, and of the glans
clitoridis before. This is the para intermedia of Kobelt, and is regarded
by him as corresponding with the part of the male corpus spongiosum
urethras which is in front of the bulb : it receives large veins coming direct
from the nymphse.
Vessels.— The outermost parts of the vulva are supplied by the superficial pudendal
arteries; the deeper parts and all the erectile tissues receive branches from the internal
pudic arteries, as in the male. The veins also in a great measure correspond ; there is a
vena dorsalis clitoridis, receiving branches from the glans and other parts as in the
male ; the veins of the bulbus vestibuli pass backwards into the vaginal plexuses,
and are connected also with the obturator veins ; above they communicate with the
3 s 2
980 FEMALE ORGANS OF GENERATION.
veins of the pars intermedia, those of the corpora cavernosa and the glans of the
clitoris, and also with the vena dorsalis. The lymphatics accompany the blood-
vessels.
Nwoe*. — Besides sympathetic branches, which descend along the arteries, especially
for the erectile tissues, there are other nerves proceeding from the lumbar and sacral
plexuses ; those from the former being the branches of the genito-crural (p. 660), and
those from the latter of the inferior pudendal and internal pudic nerves (p. 675),
which last sends comparatively large branches to the clitoris. The mode of termina-
tion is not known with certainty ; tactile corpuscles have been seen in the human
clitoris, and Pacinian bodies in that of some animals.
THE FEMALE URETHRA.
The female urethra, as compared with that of the other sex, is short,
representing only the upper half of the prostatic part of the male passage.
It is about an inch and a-half in length, and is wide and capable of great
distension ; its ordinary diameter is about three or four lines, but it en-
larges towards its vesical orifice. The direction of this canal is downwards
and forwards, and it is slightly curved and concave upwards. It lies
imbedded in the upper or rather the anterior wall of the vagina, from
which it cannot be separated.
The external orifice, or meatus urinarius, opens in the vulva, beneath
the symphysis pubis, nearly an inch below and behind the clitoris, between
the nymphee, and immediately above the entrance to the vagiiia. From its
orifice, which is its narrowest part, the canal passes upwards and back-
wards between the crura of the clitoris and behind the pubes, gradually
enlarging into a funnel-shaped opening as it approaches and joins the neck
of the bladder. There is also a dilatation in the floor of the canal, just
within the meatus.
The mucous membrane is whitish, except near the orifice ; it is raised
into longitudinal plicre, which are not entirely obliterated by distension,
especially one which is particularly marked on the lower or posterior sur-
face of the urethra. Near the bladder the membrane is soft and pulpy,
with many tubular mucous glands. Lower down these increase in size and
lie in groups, between the longitudinal folds, and immediately within and
around the orifice, the lips of which are elevated, are several larger and
wider crypts.
The lining membrane is covered with a scaly epithelium, but near the
bladder the particles become spheroidal. The submucous areolar tissue
contains elastic fibres. Outride this there is a highly vascular structure, in
which are many large veins. Between the anterior and, posterior layers of
the triangular ligament, the female urethra is embraced by the fibres of the
compressor urethras muscle.
The vessels and nerves of the female urethra are very numerous, and are
derived from the same sources as those of the vagina.
THE VAGINA.
The vagina is a membranous and dilatable tube, extending from the
vulva to the uterus, the neck of which is embraced by it. It rests below
and behind on the rectum, supports the bladder and urethra in front, and
is enclosed between the levatores ani muscles at the sides. Its direction is
curved backwards and upwards : its axis corresponding below with that of
the outlet of the pelvis, and higher up with that of the pelvic cavity. In
consequence of being thus curved, its length is greater along the posterior
than along the anterior wall, being in the latter situation about four inches,
THE VAGIXA.
981
while in the former it amounts to five or six. Each end of the vagina is
somewhat narrower than the middle part : the lower, which is continuous
with the vulva, is the narrowest part, and has its long diameter from before
Fig. 683.
Fig. 683. — SECTIONAL VIEW OF THE VISCERA OF THE FEMALE PELVIS (after Houston
and from nature), i
p, promontory of the sacrum ; s, symphysis of the pubes ; v, the upper part of the
urinary bladder; v', the neck; v', n, the urethra ; u, the uterus; va, the vagina; r,
the point of union of the middle and lower parts of the rectum : »•', the fold between the
middle and upper parts of the rectum; a, the anus; I, the right labium ; n, the right
nymph a ; A, the hymen ; cl, the divided clitoris with the prepuce. The pelvic viscera,
having been distended and hardened jwith alcohol previously to making the section, appear
somewhat larger than natural.
backwards ; the middle part is widest from side to side, being flattened
from before backwards, so that its anterior and posterior walls are ordinarily
in contact with each other : at its upper end it is rounded, and expands to
receive the vaginal portion of the neck of the uterus, which is embraced by
it at some distance from the os uteri. The vagina reaches higher up on
the cervix uteri behind than in front, so that the uterus appears, as it were,
to be let into its anterior wall.
On the inner surface of the vagina, along the anterior and the posterior
walls, a slightly elevated ridge extends from the lower end upwards along
the middle line, similar to the raphe in other situations : these ridges are
named the columns of the vagina, or columnce rugarum. Numerous den-
tated transverse ridges, called rugce, will also be observed, particularly in
persous who have not borne children, running at right angles from the
982 FEMALE ORGANS OF GENERATION.
columns. These columns and rugae are most evident near the entrance of
the vagina and on the anterior surface, and gradually become less marked,
and disappear towards its upper end.
Structure and connections. — The walls of the vagina are thickest in front,
in the vicinity of the urethra, which indeed may be said to be imbedded
in the anterior wall of the vaginal passage ; in other situations they are
thinner. The vagina is firmly connected by areolar tissue to the neck of
the bladder, and only loosely to the rectum and levatores ani muscles ; at
the upper end, for about a fourth part of its length, it receives a covering
behind from the peritoneum, which descends in the form of a cul-de-sac
thus far between the vagina and the rectum.
Externally the vagina presents a coat of dense areolar tissue, and be-
neath this its walls are composed of unstriped muscle, which is not distinctly
separable into strata, but is composed chiefly of fibres internally circular
and externally longitudinal. Round the tube a layer of loose erectile
tissue is found, which is most marked at the lower part.
At its lower end, the vagina is embraced by muscular fibres, which con-
stitute the sphincter vagince, already described (p. 266).
The mucous membrane, besides the columns and rugae, is provided with
conical and filiform papillae, numerous muciparous glands and follicles,
especially in its upper smoother portion and round the cervix uteri.
This membrane, which is continuous with that of the uterus, is covered
with a squamous epithelium.
The vagina is largely supplied with vessels and nerves. The arteries. are derived
from branches of the internal iliac, viz., the vaginal, internal pudic, vesical, and
uterine (pp. 422, 428). The veins correspond ; but they first surround the vagina
with numerous branches, and form at each side a plexus named the vaginal plexus.
The nerves are derived from the hypogastric plexus of the sympathetic, and from the
fourth sacral and pudic nerves of the spinal system ; the former are traceable to the
erectile tissue (p. 704).
THE UTERUS.
The uterus, womb, or matrix, is a hollow organ, with very thick walls,
which is intended to receive the ovum, retain and support it during the
development of the fcetus, and expel it at the time of parturition. The
ova, discharged from the ovaries, reach the uterus by the Fallopian tubes,
which open, one at each side, into the upper part of that organ. During
pregnancy, the uterus undergoes a great enlargement in size and capacity,
as well as other important changes. In the fully developed virgin condi-
tion, which is that to which the following description applies, it is a pear-
shaped body, flattened from before backwards, situated in the cavity of the
pelvis, between the bladder and rectum, with its lower extremity projecting
into the upper end of the vagina. It does not reach above the brim of the
pelvis. Its upper end is turned upwards and forwards, whilst the lower is
in the opposite direction ; so that its position corresponds with that of the
axis of the inlet of the pelvis, and forms an angle or curve with the axis of
the vagina, which corresponds with that of the outlet of the cavity. The
uterus projects, as it were, upwards into a fold of the peritoneum, by
which it is covered behind and above, and also in front, except for a short
distance towards the lower end, where it is connected with the base of the
bladder. Its free surface is in contact with the other pelvic viscera, some
convolutions of the small intestine usually lying upon and behind it.
From its two sides the peritoneum is reflected iu the form of a broad
FORM AND POSITION OF THE FTEEUS.
983
duplicature, named the ligamentum latum, which, together with the parts
contained within it, will be presently described.
Fig. 684.
Fig. 684. — ANTERIOR VIEW OP THE UTERUS AND ITS APPENDAGES, 5
a, fundus ; 6, body ; c, cervix ; e, front of the upper part of the vagina ; n, n, round
ligaments; r, r, broad ligaments; s, s, Fallopian tubes; t, fimbriated extremity; u,
ostium abdominale ; the position of the ovaries is indicated through the broad ligaments,
and the cut edge of the peritoneum is shown along the side of the broad ligaments and
across the front of the uterus.
The average dimensions of the utems are about three inches in length,
two in breadth at its upper and wider part, and nearly an inch in thick-
ness : its weight is from seven to twelve drachms. It is usually described
as possessing a fundus, body, and neck.
The fundus is the broad upper end of the body, and projects convexly
upwards from between the points of attachment of the Fallopian tubes.
During gestation, its convexity is greatly increased, and it surrounds a
large part of the uterine cavity. The body gradually narrows as it
extends from the fundus to the neck ; its sides are straight ; its ante-
rior and posterior surfaces are both somewhat convex, but the latter more
so than the former. At the points of union of the sides with the rounded
superior border or fundus, are two projecting angles, with which the Fal-
lopian tubes are connected, the round ligaments being attached a little
before, and the ovarian ligaments behind and beneath them : these three
parts are all included in the duplicature of the broad ligaments. The
neck, or cervix uteri, narrower and more rounded than the rest of the organ,
is from six to eight lines long ; it is continuous above with the body, and,
becoming somewhat smaller towards its lower extremity, projects into the
upper end of the tube of the vagina, which is united all round with the
substance of the uterus, but extends upwards to a greater distance behind
than in front. The projecting portion is sometimes named the vaginal part.
The lower end of the uterus presents a transverse aperture, by which its
cavity opens into the vagina ; this is named variously as uteri, os uteri ex-
ternuniy and (from some supposed likeness to the mouth of the tench fish)
os tincce. It is bounded by two thick lips, the posterior of which is the
thinner and longer of the two, while the anterior, although projecting less
984
FEMALE ORGANS OF GENERATION.
from its vaginal attachment, is lower in position, and, when the tube is
closed, rests on the posterior wall of the vagina. These borders or lips are
generally smooth, but, after parturition, they frequently become irregular,
and are sometimes fissured or cleft.
<\
Fig. 685. — POSTERIOR VIEW OF THE UTERUS AND ITS APPENDAGES.
The cavity of the uterus has been opened by the removal of the posterior wall, and the
upper part of the vagina has been laid open ; a, fundus ; b, body ; c, cervix ; d, on the
anterior lip of the os uteri externuin ; e, the interior of the vagina ; /, section of the
walls of the uterus ; i, opening of the Fallopian tube ; o, ovary ; p, ligament of the
ovary ; ?•, broad ligament ; s, Fallopian tube ; t, its fimbriated extremity.
Owing to the great thickness of its walls, the cavity of the uterus is very
small in proportion to the size of the organ. The part within the body of
the organ is triangular, and flattened from before backwards, so that its
anterior and posterior walls touch each other. The base of the triangle is
directed upwards, and is curvilinear, the convexity being turned towards the
interior of the uterus. This form is owing to the prolongation of the cavity
through the substance of the organ towards its two superior angles, where
two minute foramina lead into the Fallopian tubes. At the point where the
body is continuous below with the neck, the cavity is slightly constricted,
and thus forms what is sometimes named the internal orifice (os uteri inter-
numt isthmus vel ostium uteri) ; it is often smaller than the os externuin,
and is a circular opening. That portion of the cavity which is within
the neck, resembles a tube slightly flattened before and behind ; it is some-
what dilated in the middle, and opens inferiorly into the vagina by the os
tincse. Its inner surface is marked by two longitudinal ridges or columns,
which run, one on the anterior, the other on the posterior wall, and from
both of which rugse are directed obliquely upwards on each side, so as to
present an appearance which has been named arbor vitce uterinus, also palmce
plicatca : this structure is most strongly marked anteriorly.
Structure. — The walls of the uterus consist of an external serous cover-
ing, an internal mucous membrane, and an intermediate proper tissue. The
peritoneal layer covers the fundus and body, except at the sides and for
about half an inch of the lower part of the body in front, which is attached
to the base of the bladder.
The proper tissue of the uterus constitutes much the greater part of
its walls, which are thickest opposite the middle of the body and fundus,
STBUCTURE OF THE UTERUS. 985
and are thinnest at the entrances of the Fallopian tubes. The tissue is
very dense : it is composed of bundles of muscular fibres of the plain
variety, of small size in the unimpregnated uterus, interlacing with each
other, but disposed ia bands and layers, intermixed with much fibro-areolar
tissue, a large number of blood-vessels and lymphatics, and some nerves.
The areolar tissue is more abundant near the outer surface. The arrange-
ment of the muscular fibres is best studied in the uterus at the full period
of gestation, in which the bands and layers formed by them become aug-
mented in size, and much more distinctly developed. They may be referred
to three sets or orders, viz., external, internal, and intermediate. Those of
the external set are arranged partly in a thin superficial sheet, immediately
beneath the peritoneum, and partly in bands and incomplete strata, situated
more deeply. A large share of these fibres arch transversely over the
fundus and adjoining part of the body of the organ, and converge at either
side towards the commencement of the round ligaments, along which they
are prolonged to the groin. Others pass off in like manner to the Fallopian
tubes, and strong transverse bands from the anterior and posterior surfaces
are extended into the ovarian ligaments. A considerable number of thinly
scattered fibres also pass at each side into the duplicature of the broad
ligament, and others are described as running back from the cervix of the
uterus into the recto-uterine folds or plicae semilunares. The fibres of the
subperitoneal layer are much mixed with areolar tissue, especially about
the middle of the anterior and posterior surfaces of the uterus, in which
situation many of the super6cial fibres appear to have as it were a median
attachment from which they diverge. The fibres on the inner surface of
the uterus are disposed with comparative regularity in its upper part, being
arranged there in numerous concentric rings round the openings of the
two Fallopian tubes, the outermost and largest circles of the two series
meeting from opposite sides in the middle of the uterus. Towards the
cervix the internal fibres run more transversely ; elsewhere they take
various directions. The intermediate fibres, between the external and
internal set, pass in bands among the blood-vessels, following less regular
courses.
The mucous membrane which lines the uterus is thin and closely adherent
to the subjacent substance, especially in the body of the organ. It is con-
tinued from the vagina, and into the Fallopian tubes. Between the rugsa
of the cervix, already described, it is provided with numerous mucous
follicles and glands. There are also occasionally found in the same situa-
tion certain small transparent vesicular bodies, which, from an erroneous
opinion as to their nature, were named the ovula Nabothi. They appear
to be closed and obstructed mucous follicles, distended with a clear viscous
fluid. In the inferior third or half of the cervix, the mucous membrane
presents papillae covered with ciliated epithelium.
In the body of the uterus the mucous membrane is thin, smooth, soft,
and of a reddish-white colour. When viewed with a magnifying lens, it is
found to be marked with minute dots, which are the orifices of nume-
rous simple tubular glands, somewhat like those of the intestine. Some
of these tubular glands are branched, and others are slightly twisted into
a coil. These glands can be distinctly seen in the unimpregnated and in
the virgin uterus, but they become enlarged and more conspicuous after im-
pregnation (fig. 686). The epithelium is columnar and ciliated.
Ligaments of the uterus. — Where the peritoneum is reflected from the
uterus to the bladder in front, and to the rectum behind, it forms, in each
986 FEMALE ORGANS OF GENERATION.
position, two semilunar folds, which are sometimes called respectively, the
anterior and the posterior ligaments of the uterus. The former are also
named the vesico-uterine, and the latter, which are more marked, the recto-
uterine folds.
Fig. 686. T5
Fig. 686, A. — SECTION OP THE GLANDULAR STRUCTURE OP THE HUMAN UTERUS AT THE
COMMENCEMENT of PREGNANCY (from E. H. Weber), f
a, part of the cavity of the uterus showing the orifices of the glands ; d, a number of
the tubular glands, some of which are simple, others slightly convoluted and divided at
the extremities.
Fig. 686, B. — SMALL PORTION OP THE UTERINE Mucous MEMBRANE AFTER RECENT
IMPREGNATION, SEEN FROM THE INNER SURFACE (from Sharpey). ^
The specimen is represented as viewed upon a dark ground, and shows the orifices of
the uterine glands, in most of which, as at 1, the epithelium remains, and in some, as at
2, it has been lost.
The broad ligaments (ligamenta lata) are formed on each side by a fold of
the peritoneum, which is directed laterally outwards from the anterior and
posterior surfaces of the uterus, to be connected with the sides of the pelvic
cavity. Between the two layers of the serous membrane are placed, first,
the Fallopian tube, which, as will be more particularly described, runs along
the upper margin of the broad ligament ; secondly, the round ligament,
which is in front ; thirdly, the ovary and its ligament, which lie in a
special offshoot of the ligamentum latuin, behind ; and, lastly, blood-
vessels, lymphatics, and nerves, with some scattered fibres from the super-
ficial muscular layer of the uterus. The ligament of the ovary is merely a
dense fibro-areohir cord, containing also, according to some authorities,
uterine muscular fibres, and measuring about an inch and a half in length,
which extends from the inner end of the ovary to the upper angle of the
uterus, immediately behind and below the point of attachment of the
Fallopian tube ; it causes a slight elevation of the posterior layer of the
serous membrane, and, together with the ovary itself, forms the lower limit
of a triangular portion of the broad ligament, which has been named the
ala vespertilionis or bat's wing.
The round ligaments are two cord -like bundles of fibres, about four or five
inches in length, attached to the upper angles of the uterus, one on either
side (ligamentum teres uteri), immediately in front of the Fallopian tube.
From this point each ligament proceeds upwards, outwards, and forwards, to
gain the internal inguinal ring ; and after having passed, like the spermatic
cord in the male, through the inguinal canal, reaches the fore part of the
pubic symphysis, where its fibres expand and become united with the
CHANGES OF THE UTERUS IN GESTATION, &c. 987
substance of the mons Veneris. Besides areolar tissue and vessels, the
round ligaments contain plain muscular fibres, like those of the uterus,
from which, indeed, they are prolonged. Each ligament also receives a
covering from the peritoneum, which, in the young subject, is prolonged
under the form of a tubular process for some distance along the inguinal
canal : this, which resembles the processus vaginalis originally existing in
the same situation in the male, is named the canal of Nuck : it is generally
obliterated afterwards, but is sometimes found even in advanced life.
Blood-vessels and Nerves. — The arteries of the uterus are four in number, viz., the
right and left ovarian (which correspond to the spermatic of the male) and the two
uterine. Their origin, as well as the mode in which they reach the uterus and ovaries,
has been already described (pp. 414, 422). They are remarkable for their frequent
anastomoses, and also for their singularly tortuous course ; within the substance of
the uterus they seem to be placed in little channels or canals. The veins correspond
with the arteries ; they are very large, and form the uterine plexuses, and their thin
walls are in immediate contact with the uterine tissue. The course of the lymphatics
is described at p. 495 ; they are very large and abundant in the gravid uterus. The
nerves have been fully described at p. 704. They are derived from the inferior
hypogastric plexuses, the spermatic plexuses, and the third and fourth sacral
nerves.
The changes which take place in the uterus from age, menstruation, and gestation,
and the characters presented by this organ after it has once performed the latter func-
tion, can only be very generally indicated here.
For some time after menstruation first commences, the uterus becomes rounder
and slightly enlarged at each period, its os externum becomes more rounded, and
its lips swollen ; subsequently these periodical alterations are not so marked. The
organ itself, however, always becomes more turgid with blood, and the mucous mem-
brane appears darker, softened, and thickened.
In gestation more extensive alterations ensue, which necessarily affect the size, shape,
and position of the organ, the thickness and amount of substance in its walls, the dimen-
sions and form of its cavity, and the character of its cervix and of its os externum and os
internum. Its weight increases from about one ounce to one pound and a half or even
three pounds. Its colour becomes darker, its tissue less dense, its muscular bundles more
evident, and the fibres more developed. The principal increase is in the muscular
tissue, and this increase takes place not only by the enlargement of already existing
elements, the fibre-cells becoming enlarged from seven to eleven times in' length, and
from two to five times in breadth (Kolliker), but also by new formation. The former
process is general ; the latter occurs mainly in the innermost layers, and continues
until the sixth month of pregnancy, when new formation ceases. The round liga-
ments become enlarged, and their muscular structure more marked ; the broad liga-
ments are encroached upon by the intrusion of the growing uterus between their
layers. The mucous membrane and the glands of the body of the uterus become the
seat of peculiar changes, which lead to the formation of the decidual membrane;
whilst the membrane of the cervix loses its columns and rugae. The blood-vessels
and lymphatics are greatly enlarged, and it is observed that the arteries become
exceedingly tortuous as they ramify upon the organ. The condition of the nerves in
the gravid uterus has been previously fully referred to (p. 704).
After parturition, the uterus again diminishes, its enlarged muscular fibres under-
going oleaginous degeneration and becoming subsequently absorbed, while a new set
of minute fibre cells are developed. The organ, however, never regains its original
virgin character. Its weight usually remains from two to three ounces in those who
have had children ; its cavity is larger ; the os externum is wider and more rounded,
and its margins often puckered or fissured ; the arteries continue much more tortuous
than they are in the virgin, and its muscular fibres and layers remain more defined.
Age. — In the infant, the neck of the uterus is larger than the body ; and the
fundus is not distinguished either by breadth or by convexity of outline. These parts
afterwards enlarge gradually, until, at puberty, the pyriform figure of the womb is
fully established. The arbor vitse is very distinct, and indeed at first reaches up-
wards to the highest part of the cavity.
FEMALE ORGANS OF GENERATION.
From the gradual effects of more advanced age alone, independent of impreg-
nation, the uterus shrinks, and becomes paler in colour, and harder in texture ; its
triangular form is lost ; the body and neck become less distinguishable from each
other ; the orifices also become less characteristic.
For further details with regard to uterine changes, the reader is referred to Farre
on " Uterus and its Appendages " in Cyclop, of Anat. and Phys.
THE OVARIES AND FALLOPIAN TUBES.
The ovaries, the parts corresponding to the testicles of the male (ovaria,
testes muliebres), are two somewhat flattened oval bodies, which are placed
one on each side, nearly horizontally, at the back of the broad ligament of
the uterus, and are enveloped by its posterior membranous layer. The
ovaries are largest in the virgin state ; their weight is from three to five
scruples, and they usually measure about one inch and a half in length,
three-quarters of an inch in width, and nearly half an inch in thickness ;
but their size is rather variable. Each ovary is free on its two sides, and
also along its posterior border, which has a convex outline ; but it is
attached by its anterior border, which is straighter than the other, and along
the line of its attachment exhibits a deep hilus by which the vessels and
nerves enter. Its inner end is generally narrow, and is attached to the
dense cord already described as the ligament of the ovary, which connects
it with the uterus. Its outer extremity is rcore obtuse and rounded, and
has attached to it one of the fimbrira of the Fallopian tube.
Structure. — The colour of the ovaries is whitish, and their surface is
either smooth, or more commonly irregular, and often marked with pits
or clefts resembling scars. Beneath the peritoneal coat, which covers it
everywhere except along its attached border, the ovary is enclosed in a
proper fibrous coat (tunica albuginea), of a whitish aspect and of consider-
able thickness, which adheres firmly to the tissue beneath, being in struc-
tural continuity with it. When the deeper ovarian substance is divided, it
is seen to consist of a firm reddish- white vascular structure called the
Fig. G87. Fig. 687. — VIEW OF A SEC-
TION OF THK PREPARED
OVARY OF THE CAT (from
Sehron). f
1, outer covering and
free border of the ovary ;
1', attached border ; 2, the
ovarian stroraa, present-
ing a fibrous and vascular
structure ; 3, granular sub-
stance lying external to the
fibrous stroma; 4, blood-
vessels ; 5, ovigerms in
their earliest stages occupy-
ing a 'part of the granular
layer near the surface ; 6,
ovigerms which have begun
to enlarge and to pass more
deeply into the ovary ; 7,
ovigerms round which the
Graafian follicle and tunica granulosa are now formed, and which hare passed somewhat
deeper into the ovary and are surrounded by the fibrous stroma ; 8, more advanced
Graafian follicle with the ovum imbedded in the layer of cells constituting the proligerous
disc ; 9, the most advanced follicle containing the ovum, &c. : 9', a follicle from which the
ovum has accidentally escaped ; 10, corpus luteurn presenting radiated columns of cellular
structure.
THE OVARIES— GRAAFIAN VESICLES.
989
stroma, the fibres of which, although forming a felted tissue, have, with
the blood-vessels, principally a radiating direction from the lulus to the rest
of the surface. It contains numerous spindle -shaped cells, and also, ac-
cording to some writers, uustriped muscular tissue. Towards the surface,
the ovarian tissue, which in this part has been distinguished as cortical, pre-
sents, especially in children, a different appearance from the deeper or
medullary part, from being granular, and having within it great numbers of
small vesicles, the Graafian vesicles or follicles, which are absent from the
deep part. After the period of puberty, a certain number of the Graafian
vesicles, varying from twelve to thirty or more, have attained a larger size,
some having a diameter of from -jgth to ^th of an inch, or even more.
The great majority however, remain much smaller : thus Henle estimated
the number of vesicles of about ^ to -g^th °^ au *nck *n diameter, in the
two ovaries of a girl of eighteen, at 72,000 (Syst. Anat., II. 483).
The vesicles of DQ Graaf, when dilated, are filled in part with a clear,
colourless, albuminous fluid, the larger ones approaching the surface of the
ovary, on which they may sometimes be distinguished as semi-transparent
elevations. Each of these vesicles includes, besides its fluid contents, the
ovum — a small round vesicular body, imbedded in a layer of cellular sub-
stance. Sometimes, though rarely, two ova have been found iu one vesicle.
Fig. 688.
Fig. 688. — VIEW OP A PORTION OP THE SECTION OF THE PREPARED CAT'S OVARY,
REPRESENTED IN THE PRECEDING FIGURE, MORE HIGHLY MAGNIFIED (from SchlOu).
1, outer covering of the ovary ; 2, fibrous stroma ; 3, cortical layer of granular sub-
stance towards the surface ; 3', deeper parts of the granular substance ; 4, blood-
vessels ; 5, ovigerms forming a layer near the surface ; b', one or two of the ovigerms
sinking a little deeper and beginning to enlarge ; 7, one of the ovigerms farther developed,
DOW enclosed by a prolongation of the fibrous stroina, and consisting of a small Graafian
follicle, within which is situated the ovum covered by the cells of the discus proligerus ;
8, a follicle farther advanced ; 8', another which is irregularly compressed ; 9, the greater
part of the largest follicle, in which the following indications are given ; a, epithelial or
cellular lining of the follicle constituting the mernbrana granulosa ; b, the portion reflected
over the ovum named discus proligerus ; c, vitellus or yelk part of the ovum surrounded
by a vesicular membrane, which becomes afterwards the zona pellucida ; d, germinal
vesicle ; e, germinal spot or nucleus.
990 FEMALE ORGANS OF GENERATION.
The developed vesicle lias two coats, viz., an external vascular tunic,
and an internal tunic named the ovicapsule, which is lined with a cellular or
epithelial layer, the membrana granulosa. At first the ovum appears near
the centre of the vesicle, while the latter is still very small, but, in the
mature condition, it lies towards the internal surface of the ovi-capsule, im-
bedded in the discus proligerus, a small flattened heap of granular cells,
continuous with the membrana granulosa.
The ovum itself, first discovered in mammals by Baer, is a spherical body,
very constant in size, being about -j-i^th of an inch in diameter ; it consists
of a thick, colourless, and transparent envelope (zona pellucida), which
surrounds the substance of the yelk. Within the yelk, which is made up
of granular matter, is situated a still smaller vesicular body, named the
germinal vesicle, which is about -y^th of an inch in diameter ; and in this
again is an opaque spot, having a diameter only of -j-g-1^ ^th to -^/^th of
an inch, and named the germinal spot (macula germinativa).
The ova make their appearance in the ovary at so early a period that even
at the time of birth it has been found too late to observe their mode of origin.
It has been ascertained that the ovum makes its appearance before the
ovisac, and that the germinal vesicle is the first part of the ovum to be
formed, the granular substance of the yelk being gradually deposited round
it. Around the ovum a circle of cells becomes visibles grows thicker,
and divides into two layers, the outer of which becomes the membrana
granulosa, while the inner adheres to the ovum, forming the discus proli-
gerus. The precise nature and mode of origin of .the inner tunic of the
Graafian vesicle is matter of dispute, and indeed Henle denies that there
is any homogeneous membrane distinct from the outer cells of the membrana
granulosa.
According to Schron's observations on the cat, the ova make their first appearance
near the surface of the ovary, and the vesicles become deeper placed tis they grow
larger : it is only in the later stages of growth, when the great expansion of the
vesicles presses aside the surrounding tissues, that they are again brought into con-
tact with the surface. From observations by Grohe it appears that the process is
similar in the human ovary. A beaded arrangement of the ova, as if developed in
anastomosing primitive gland tubes, has been observed by Valentin in the ovaries
of young animals, and more recently by Pfliiger in the adult cat. Spiegelberg finds
similar appearances in the human foetus. But the existence of such tubular glandular
structure and its relation to the commencing ova is still under discussion, and requires
farther observation for its determination.
Fig. 689. — OVUM OP THE Sow REMOVED FROM THE
GRAAFIAN VESICLE, WITH ITS CELLULAR COVERING (from
M. Barry). ^p
1, germinal spot or nucleus ; 2, germinal vesicle ; 3, the
yelk ; 4, the zona pellucida or external covering of the
ovum ; 5, part of the tunica granulosa or proligerous disc ;
6, some adherent granules or cells.
The Graafian vesicle, as it becomes more fully
5 4 ,s dilated, approaches the surface of the ovary. By
rupture of the vesicle the ovu-n, covered by the
cells of its proligerous disc, escapes into the Fallopian
tube, and is thus conveyed into the womb, while
the ruptured vesicle becomes converted, by hypertrophy of its walls, into a
yellow mass named corpus luteum, which after persisting for a time, dwindles
down into a small fibrous cicatrix.
THE FALLOPIAN TUBES.
991
On the subject of the ovum the following works may be mentioned : —
Martin Barry's Researches on Embryology, in Phil. Trans., 1838 and 1839 ;
Allen Thomson, Article "Ovum," in Cyclop, of Anat. and Phys. , where
also the literature will be found referred to ; Farre, " Uterus and Ap-
pendages," in the same ; Pniiger, Die Eierstocke der Saugethiere und des
Menschen, Leipzig, 1863; Schron, in Zeitsch. f. Wissenscb. Zoologie, vol.
xji. p. 409 ; Grohe, in Virchow's Archiv, vol. xxvi. p. 271 ; also in
Virchow's Archiv, vol. xxix. p. 450 ; Spiegelberg, in Virchow's Archiv,
vol. xxx. p. 466 : and Henle, in his Handbuch.
The Fallopian tubes. — These tubes, which may be considered as ducts
of the ovaries, or oviducts, and which serve to convey the ovum from
thence into the uterus, are inclosed in the free margin of the broad liga-
ments. They are between three and four inches in length. Their inner
or attached extremities, which proceed from the upper angles of the uterus,
are narrow and cord-like ; but they soon begin to enlarge, and pro-
ceeding outwards, one on each side, pursue an undulatory course, and at
length, having become gradually wider, they bend backwards and down-
wards towards the ovary, about an inch beyond which they terminate in
an expanded extremity, the margin of which is divided deeply into a
number of irregular processes named fimbrice ; one of these, somewhat
longer than the rest, is attached to the outer end of the corresponding
ovary. The wide and fringed end of the Fallopian tube, or rather trumpet,
as the term "tuba"' literally signifies, is turned downwards and towards
the ovary, and is named the fimbriated extremity (morsus diaboli). In
the midst of these fimbrise, which are arranged in a circle, the tube itself
opens by a round constricted orifice, ostium abdominale, placed at the
Fig. 690.
Fig. 690. —DIAGRAMMATIC VIEW OP THE UTERUS AND ITS AI-PENDAGES, AS SEEN FROM
BEHIND. jL
The uterus and upper part of the vagina have been laid open by removing the posterior
wall ; the Fallopian tube, round ligament, and ovarian ligament have been cut short and
the broad ligament removed on the left side ; u, the upper part of the uterus ; c, the
cervix opposite the os internum ; the triangular shape of the uterine cavity is shown and
the dilatation of the cervical cavity with the rugae termed arbor vitse ; v, upper part of the
vagina ; od, Fallopian tube or oviduct ; the narrow communication of its cavity with
that of the cornu of the uterus on each side is seen ; I, round ligament ; lo, ligament of
the ovary ; o, ovary ; i, wide outer part of the right Fallopian tube ; f i, its fimbriated
extremity ; po, parovarium ; h, one of tlie bydaiids frequently found connected with the
broad ligament.
992 FEMALE ORGANS OF GENERATION.
bottom of a sort of fissure leading from that fringe which, is attached to
the ovary. It is by this orifice that an ovum is received at the time
of its liberation from the ovary, and is thence conveyed along the tube
to its uterine extremity, which opens into the womb by a very miuute
orifice, admitting only a fine bristle, and named ostiwm uterinum. The part
of the canal which is near the uterus is also very fine, but it becomes
gradually larger towards its abdominal orifice, and there it is again some-
what contracted : hence, the term isthmus, given by Henle to the uterine
half, and ampulla to the outer half of the Fallopian tube.
Beneath the external or peritoneal coat the walls of the tube contain,
besides areolar tissue, plain muscular fibres like those of the uterus, arranged
in an external longitudinal and an internal circular layer. The mucous
membrane lining the tubes i* thrown into longitudinal plicso, which are
broad and numerous in the wider part of the tube, and in the narrower
part are broken up into very numerous arborescent processes : it is con-
tinuous, on the one hand, with the lining membrane of the uterus, and at
the outer end of the tube with the peritoneum ; presenting an example of
the direct continuity of a mucous and serous membrane, and making the
peritoneal cavity in the female an exception to the ordinary rule of serous
cavities, i.e. of being perfectly closed. The epithelium in the interior of the
Fallopian tube is, like that of the uterus, columnar and ciliated ; the inner
surface of the fimbrisB is also provided with cilia, and Henle has even
detected ciliated epithelium on their outer or serous surface, but it here soon
passes into the scaly epithelium of the peritoneal membrane.
Vessels and nerves of the ovaries and Fallopian tubes. — The ovaries are supplied by
the ovarian arteries, analogous to the spermatic in the male, which anastomose freely by
an internal branch with the termination of the uterine arteries. Sometimes this anasto-
motic branch is so large that the ovary seems to be supplied almost entirely by the
uterine artery. The ovarian artery always sends numerous branches to the Fallopian
tube. The smaller arteries penetrate the ovary along its attached border, pierce the
proper coat, and run in flexuous parallel lines through its substance. The veins cor-
respond, and the ovarian veins form a plexus near the ovary named the pampiniform
plexus. The nerves are derived from the spermatic or ovarian plexus ; and also from
one of the uterine nerves, which invariably send an offset to the Fallopian tube.
The parovarium (Kobelt), or Organ of Rosenmiiller, is a structure which
can usually be brought plainly into view by holding against the light the
fold of peritoneum between the ovary and Fallopian tube. It con-
sists of a group of scattered tubules lying transversely between the Fallo-
pian tube and ovary, lined with epithelium, but having no orifice. The
tubules converge, but remain separate at their ovarian end, and at the other
are more or less distinctly united by a longitudinal tube. The parovarium
consists of a few tubules formed in connection with the Wolffian body, which,
partaking in the growth of the surrounding textures, have remained per-
sistent during life. The duct which unites them is sometimes of consider-
able size, and is prolonged for some distance downwards, in the broad liga-
ment. Its more developed form in some animals constitutes the duct of
Gaertner, afterwards referred to as arising from a persistent condition of the
Wolffian duct.
DEVELOPMENT OF THE URINARY ORGANS.
The Wolffian Bodies and their Excretory ducts. — The development of the genito-
urinary organs in reptiles, birds, and mammalia, including man, is preceded by the
formation of two temporary glands, named after their discoverer, C. F. Wolff, the
DEVELOPMENT. WOLFFIAN BODIES.
993
Wolffian Bodies. In the embryos of the higher mammalia these organs are propor-
tionally smaller, and disappear earlier than in those of the lower mammalia, birds,
or reptiles. In' the human subject, accordingly, the Wolffian bodies are relatively
small, and are found only in an early stage of foetal development. In the mammalian
embryo, at a period when the intestinal canal still communicates with the umbilical
vesicle by a wide orifice, the Wolffian bodies appear in the form of two slight ridges
of blastema, placed one on each side of the line of attachment of the intestine to the
vertebral column. On reaching their full size, which in man seems to take place
about the fifth week of embryonic life, they have the appearance of two oblong
reddish masses placed on the aides of the vertebral column, and extending from the
lower end of the abdomen to the vicinity of the heart. Their structure is glandular ;
clear pedunculated vesicles may be early discovered in them, opening into an excretory
Fig. 691. — DIAGRAM OP THE Fig. 691.
WOLFFIAN BODIES, MULLERIAN
DUCTS, AND ADJACENT PARTS,
PREVIOUS TO SKXITAL DISTINC-
TION, AS SEEN FROM BEFORE.
s r, the suprarenal bodies ; r,
kidneys; ot, common blastema of
ovaries or testicles ; W, Wolffian
bodies ; w, Wolffian ducts ; m, m,
Miillerian ducts ; yc, genital cord ;
u g, sinus urogenitalis ; i, intes-
tine ; c I, cloaca.
duct which runs along the outer
side of each organ. These
vesicles subsequently become
lengthened into transverse and
somewhat tortuous ccecal tubes,
•which still retain a dilatation,
like the capsule of a Malpighian
body, at their inner extremity.
The Wolffian bodies are highly
vascular, their larger blood-
vessels running between and
parallel with the transverse
tubules. In the embryo of the
coluber natrix, Rathke first
observed vascular tufts, which
he compared to the Malpighian
corpuscles of the kidneys; and
since the time of his discovery,
Malpighian tufts have been found in the Wolffian bodies of birds and mammals.
The ducts of the two bodies open into the sac of the allantois, to be presently
described.
A whitish secretion has been seen in the ducts of the Wolffian bodies of birds and
serpents resembling the urine of those animals, and as the fluid of the allantois also
has been found to contain uric acid, it is reasonable to think that the Wolffian bodies
perform the office of kidneys during the early part of foetal life. They are accord-
ingly sometimes named the primitive or primordial kidneys.
• As development advances, the Wolffian bodies rapidly become proportionally
shorter and thicker : they shrink towards the lower part of the abdominal cavity, and
soon become almost entirely wasted. By the middle of the third month only traces of
them are visible in the human embryo. They take no part in the formation of the
kidneys or suprarenal capsules, nor in that of the ovaries or body of the testes, but
are connected with the origin of a part of the seminal passages in the male sex.
The Kidneys and Ureters.— The kidneys commence subsequently to and independ-
ently of the Wolffian bodies. They already exist about the seventh week, as two small
3 T
994 DEVELOPMENT OF URINARY ORGANS.
dark oval masses, situated behind the upper part of the Wolffian bodies, which are
still large and completely hide the kidneys. Though at first smooth and oval, the
kidneys soon assume their characteristic general outline, and about the tenth week
are distinctly lobulated. The separate lobules, generally about fifteen in number,
gradually coalesce in the manner already described ; but at birth, indications of the
original lobulated condition of the kidney are still visible on the surface, and the entire
organ is more globular in its general figure than in the adult. The kidneys are then
also situated lower down than in after-life.
The formative blastema of the kidney, as observed by Eathke in the foetal calf,
soon contains a series of club-shaped bodies which have their larger ends free and
turned outwards, and their smaller ends or pedicles directed inwards towards the
future hilus, where they are blended together. As the organ grows these bodies
increase in number, and finally, becoming hollow, form the uriniferous tubes. At
first, short, wide, and dilated at their extremities, the tubuli soon become elongated,
narrow, and flexuous, occupying the whole mass of the kidney, which then appears
to consist of cortical substance only. At a subsequent period, the tubuli nearest the
hilus become straighter, and thus form the medullary substance. The tubuli, as
shown by Valentin, are absolutely, as well as relatively, wider in the early stages of
formation of the kidney. The Malpighian corpuscles have been seen by Eathke in
a sheep's embryo, the kidneys of which measured only two and a half lines in length.
With regard to the mode of the first appearance of the pelvis and ureter, the state-
ments of embryologists are very conflicting. The ureters, it is stated by Eathke,
commence after the kidneys, and then become connected with the hilus of each organ,
and with the narrow ends of the club-shaped bodies in its interior. At first, according
to him, the growing tubuli do not seem to communicate with the cavity of the ureter;
but, subsequently, when the wide upper portion of this canal or pelvis of the kidney
has become divided to form the future calyces, the pencil-like bundles of the tubuli open
into each subdivision of the ureter, and give rise at a later period to the appearance
of the papillae and their numerous orifices. The lower ends of the ureters soon come
to open into that part of the sac of the allantois which afterwards becomes converted
into the bladder. The researches of Mliller and Bischoff are in general confirmatory
of Eathke's account. Valentin believes that the ureter (which he has seen at the
earliest periods), the pelvis of the kidney, and the uriniferous tubules, are formed in a
general blastema, independently of one another ; and that, each part first becoming
separately hollowed out, their cavities afterwards communicate with each other.
BischofF states that the ureters appear at the same time as the kidneys, and are
formed in continuity with the uriniferous tubules, and moreover that all these parts,
which are at first solid, are excavated, not separately, but in common, in the farther
progress of development. Lastly, according to .Eemak's observations on the chick,
the kidneys of that animal commence as two hollow projections from the cloaca,
internal to the ducts of the Wolffian bodies, which afterwards elongate and ramify so
as to form both the ureters and kidneys.
In the advanced foetus and in the new-born infant, the kidneys are relatively larger
than in the adult, the weight of both glands, compared with that of the body, being,
according to Meckel, about one to eighty at birth.
The Suprarenal Bodies. — These organs have their origin from blastema, inde-
pendent both of the kidneys and of the Wolffian bodies. Valentin describes them as
originating in a single mass, placed in front of the kidneys, and afterwards becoming
divided. Meckel has also seen them partially blended together, Miiller has found
the suprarenal bodies in contact, but not united. BischofF has always seen them
separate, and in early conditions closely applied to the upper end of the Wolffian
bodies. Kolliker has also observed them united by a bridge of substance, in which
the splanchnic nerves were lost. Prom all this it is plain that the solar plexus and
suprarenal capsules are closely united in the early foetal state • but it by no means
follows that they have a common origin.
In quadrupeds the suprarenal bodies are at all times smaller than the kidneys ;
but in the human embryo they are for a time larger than those organs, and quite
conceal them. At about the tenth or twelfth week, the suprarenal bodies are smaller
than the kidneys ; at birth the proportion between them is 1 to 3, whilst in the
adult it is about 1 to 22. They diminish in aged persons.
ALLAXTOIS AND URINARY BLADDER. 995
The Allantois, Urinary Bladder, and UrachttB. — The name of Allantois was
originally given to a membranous sac which is appended to the umbilicus of various
quadrupeds in the foetal state, and which communicates with the urinary bladder by
means of a canal passing through the umbilical aperture, and named the urachus.
These several parts are formed out of one original saccular process, which passes
out from the cloacal termination of the intestine, and which subsequently becomes
distinguished into the bladder, the urachus, and the allantois strictly so called ;
but modern embryologists employ the term allantois also to signify the original
common representative of the several parts referred to. In this sense, an allan-
tois may be said to exist not only in mammalia, but also in birds and reptiles,
subject, however, to great differences in its subsequent development and relative im-
portance. Thus, in Batrachians it never extends beyond the abdominal cavity ; in
scaly reptiles, on the other hand, as well as in birds and in some quadrupeds, it ulti-
mately surrounds the body of the foetus, and spreads itself over the inner surface of
the chorion or outer covering of the ovum, whilst in other quadrupeds, its extra-
abdominal portion is of small extent. In man, the allantois proper is not only very
insignificant in point of size, but also extremely limited in duration, for it vanishes
at a very early period in the life of the embryo ; and, whilst in many animals it serves
both as a receptacle for the secretion of the foetal urinary organs, and as a vehicle to
conduct the umbilical vessels from the body of the embryo to the chorion to form the
placenta (or some equivalent vascular structure), it seems in the human species to
serve merely for the latter purpose. The allantoid process communicates below with
the intestinal canal, and receives the wide excretory ducts of the Wolffian bodies, the
ureters, and the Fallopian tubes or vasa deferentia. By Baer, Rathke, and others,
the allantois has been regarded as formed from the intestinal tube, and by Reichert as
developed upon the excretory ducts of the Wolffian bodies. Bischoff states that, in
the embryos of the rabbit and dog, it commences before the appearance of either the
Wolffian bodies or the intestine, as a solid mass projecting forwards from the posterior
extremity of the body. This mass soon becomes hollowed into a vesicle, which is
covered with blood-vessels, and communicates with the intestine. Continuing
rapidly to enlarge, it protrudes between the visceral plates, and, when these close
together, through the opening of the umbilicus, forming in the rabbit a pear-shaped
sac, which conveys blood-vessels (soon recognised as the umbilical vessels) to the
chorion, to form the foetal part of the placenta.
In the human embryo, the allantois ceases, at a very early period, to be found
beyond the umbilicus, and in the lower part of its extent, within the abdomen, it
becomes widened to form the bladder, whilst the upper part, or urachus, becomes
constricted, and is at length completely closed, and remains only in the form of
a ligament, with minute traces of its original hollow structure already described
along with the urinary bladder.
The lower part of the allantois, or rudimentary bladder, receiving, as already men-
tioned, the efferent canals of the Wolffian bodies, as well as those of the kidneys ami
of the ovaries or testes, at first communicates freely with the lower end of the
intestinal tube, and when this becomes opened to the exterior, there is formed a sort
of cloaca, as in adult birds and reptiles. Soon, however, a separation takes place,
so as to produce for the genito-urinary organs a distinct passage to the exterior : thia
is named the sinus urogenitalis, and is situated in front of the termination of the
intestine.
DEVELOPMENT OF THE ORGANS OF GENERATION.
The development of the parts concerned in the reproductive function does not
begin until after the rudiments of the principal organs of the body have appeared.
The internal organs of generation first make their appearance, and for a brief period
no sexual difference is perceptible in them. The external organs, which subsequently
begin to be formed, are also identical in appearance in the two sexes, as late as the
fourteenth week.
The internal Organs of Generation.— The Ovaries and. Testes. — The rudiments of
the ovaries or testes, for it cannot at first be determined which are ultimately to be
produced, appear after the formation of the allantois and Wolffian bodies, but a little
sooner than the kidneys. They consist of two small whitish oval masses of blastema
3x2
996
DEVELOPMENT OF THE GENERATIVE ORGANS.
placed on the inner border of the Wolffian bodies. At first, they are placed near to
one another, and parallel ; the Wolffian bodies being at that time large, and occu-
pying the whole posterior part of the abdomen. But as the kidneys grow, above and
internal to the Wolffian bodies, the latter are displaced outwards, and with them the
reproductive organs. At this time the sex becomes distinguishable; for in the
female the ovary becomes elongated and flattened, and it assumes at first an oblique
and then a nearly transverse direction; whereas, in the male, the testis becomes
Fig. 692.
Fig. 692. — DIAGRAM OP THE
PRIMITIVE URINARY AND SEX-
UAL ORGANS IN THE EMBRYO
PREVIOUS TO SEXUAL DIS-
TINCTION.
The parts are shown chiefly in
profile ; the kidney and supra-
renal body of the right side are
omitted, and the Miillerian and
Wolffian ducts are shown from
the front. 1, left kidney ; 2,
suprarenal body ; 3, ureter ; 4,
urinary bladder ; 5, urachus ;
ot, the mass of blastema from
which ovary or testicle is after-
wards formed ; W, left Wolffian
body ; x , part at the apex from
which the coni vasculosi are
afterwards developed in new
blastema ; w, iv, right and left
Wolffian ducts ; m, m, right and
left Miillerian ducts uniting toge-
ther and with the Wolffian ducts
in g c, the genital cord ; ug, sinus
uro-genitalis ; i, lower part of
the intestine ; c, I, common open-
ing of the intestine and uroge-
nital sinus ; c/>, elevation which
becomes clitoris or penis ; I s,
ridge from which the labia
majora or scrotum is formed.
rounder and thick, and, to-
gether with the Wolffian body,
retains its vertical position,
although displaced downwards
and outwards. Subsequently the tubuli seminiferi are developed within the testis,
and ova in the superficial strata of the ovary.
Uterus and Fallopian tubes: Epididymis and Vasa deferentia. — The excretory
duct of each Wolffian body lies from the first along its outer border, and in the
succeeding part of its course is continued down from the extremity of the Wolffian
body to the sinus urogenitalis. As the Wolffian body begins to change its position,
and at the same time decrease in size, a white thread of blastema appears on the
front of that body, and runs along the inner side of the Wolffian duct in its whole
course ; this fcrms the Mullerian duct. At the upper extremity of the Wolffian body,
and close to the white thread, there is likewise developed a pyramidal mass of blas-
tema, occupying the position originally held by the upper tubules of that gland,
which seem to be absorbed to give place to it. The Mullerian duct, commencing by a
slightly dilated extremity, descends in front of the excretory duct, to the lower end
of the Wolffian body, where it dips down in front of that body, then turns over that
duct so as to get behind it, and on arriving at the middle line comes in contact with
its fellow of the opposite side, with which, and with the lower parts of the Wolffian
ducts, it is united into a single cord, named the genital cord. The Mullerian ducts
become as it were fused together, first at the upper and lower parts of the genital
MtfLLERIAN DUCTS.
997
cord, and subsequently through its whole extent, while the Wolffian ducts remain
separate to their ends.
Another structure is likewise seen at this stage in connection with the Wolffian
body in both sexes, viz. an elevation of peritoneum, with tissue enclosed, which
extends from the lower end of the testis or ovary to the point where the excretory
and Miillerian ducts quit their contact with the lower extremity of the Wolffian
body, and, there becoming stronger, extends onwards from this point to the processus
vaginalis or canal of Nuck. The further development of these parts in each of the
two sexes requires a separate description.
Fig. 693. — DIA-
GRAM OF THE FE-
MALE TYPE OF
SEXUAL ORGANS.
Fig. 693.
This and the fol-
lowing figure repre-
sent diagrammati-
cally a state of the
pirts not actually
visible at one time ;
but they are in-
tended to illustrate
the general type in
the two sexes, and
more particularly
the relation of the
two conducting tubes
to the development
of one as the natural
passage in either
&ex, and to the
natural occurrence
of vestiges of the
other tube, as well
as to the persistence
of the whole or parts
of both tubes in oc-
casional instances of
hermaphroditic na-
ture.
1, the left kidney ;
2, suprarenal body;
3, ureter, of which
a part is removed
to show the parts
passing within it ; 4, urinary bladder ; 5, urachus ; o, the left ovary nearly in the
place of its original formation ; p o, parovarium ; W, scattered remains of Wolffian tubes
near it ; d G, remains of the left Wolffian duct, such as give rise to the duct of Gaertner,
represented by dotted lines ; that of the right side cut short is marked w ; /, the abdo-
minal opening of the left Fallopian tube ; ti, the upper part of the body of the uterus,
presenting a slight appearance of division into cornua ; the Fallopian tube of the right
side cut short is marked m ; g, round ligament, corresponding to gubernaculum ; i, lower
part of the intestine ; v a, vagina ; h, situation of the hymen ; C, gland of Bartholin
(Cowper's gland), and immediately above it the urethra ; c c, corpus cavernosuin clitoridis ;
s c, vascular bulb or corpus spongiosum ; n, nympha ; lt labium ; v, vulva.
In the female, the vagina, uterus, and Fallopian tubes are formed out of the Mttl-
lerian ducts. That portion of the ducts in which they become fused together is de-
veloped into the vagina, the cervix, and part of the body of the uterus ; and the pecu-
liarity of the mode of fusion accounts for the occurrence, as a rare anomaly, not only
of double uterus, but of duplicity of the vagina, coincident with communication
between two lateral halves of the uterus. The part of the Mullerian duct extending
from the base of the Wolffian body, to the point where the two ducts meet, constitutes
998
DEVELOPMENT OF THE GENERATIVE ORGANS.
in animals with horned uteri, the cornu of the uterus ; but in the human subject
it remains comparatively short, entering into the formation of the upper part of the
organ. The remaining upper portion of the Miillerian duct constitutes the Fallopian
tube— becoming at first open and subsequently fringed at its upper extremity. In the
peritoneal elevation between the ovary and the base of the Wolffian body the fibrous
ligament of the ovary is developed, while that part which proceeds onwards to the canal
of Nuck becomes the round ligament of the uterus. The excretory ducts of the Wolf-
fian bodies disappear in the human female, but in the pig and some ruminants they
persist as the canals of Gaertner. The parovarium is generally believed to consist of
the vestiges of some of the tubules of the Wolffian body, but it is held by Banks to
Fig. 694.
Fig. 694.— DIAGRAM OP
THE MALE TYPE OF
SEXUAL ORGANS.
1, 2, 3, 4, and 5, as
in the preceding figure ;
t, testicle in the place of
its original formation ; e,
caput epididymis ; v d,
vas deferens ; W, scat-
tered remains of the
Wolffian body constituting
the organ of Giraldes;
v h, vas aberrans ; m,
Miillerian duct, the upper
part of which remains as
the hydatid of Morgagni,
the lower part repre-
sented by a dotted line
as descending to the
sinus pocularis consti-
tutes the cornu and tube
of the uterus masculinus ;
g, the gubernaculum ;
v s, the vesicula semi-
nalis ; p r, the prostate
gland ; C, Cowper's
gland of one side ; cp,
corpora cavernosa penis
cut short; s p, corpus
spongiosum urethra ; s,
scrotum ; t', together
with the dotted lines
above, indicates the di-
rection in which the
testicle and epididymis
change place in their de-
scent from the abdomen
into the scrotum.
owe its origin to a development of tubes in the whitish blastema previously men-
tioned, which appears in connection with the upper part of that body when it begins
to shrink, and which, in the male, gives rise to the upper part of the epididymis ;
and in this view Allen Thomson is disposed to concur.
In the male, the Miillerian ducts are destined to undergo little development and
are of no physiological importance, while the ducts of the Wolffian bodies, and pro-
bably also some part of their glandular substance, form the principal part of the excre-
tory apparatus of the testicle. The united portion of the Mullerian ducts remains as
the vesicula prostatica, which accordingly not only corresponds with the uterus, as
was shown by Weber, but likewise, as pointed out by Leuckart, contains as much of
the vagina as is represented in the male. In some animals the vesicula prostatica
is prolonged into cornua and tubes ; but in the human subject the whole of tho
FORMATION OF THE EP1DIDYMIS. 999
ununited parts of the Miillerian ducts disappear, excepting, as suggested by Kobelt,
their upper extremities, which seem to be the source of the hydatids of Morgagni.
The excretory duct of the "Wolffian body, from the base of that body to its orifice, is
converted into vas deferens and ejaculatory duct, the vesicula seminalis being formed
as a diverticulum from its lower part.
With respect to the formation of the epididymis, our information is not altogether
complete. According to the greater number of the most recent observations, it
appears certain that the larger convoluted seminal tube, which forms the body and
globus minor of the-epididyinis, arises by a change or adaptation of that part of the
Wolffian duct which runs along the outer side of the organ. The vas aberrans or vasa
aberrantia of Haller appear to be the remains also in a more highly convoluted form
of one or more of the tubes of the Wolffian body still adhering to the excretory duct
of the organ, and their communication with the main tube of the epididymis receives
an explanation from that circumstance. But there are no direct observations on
record of the process of conversion of these foetal structures into the permanent forms.
As to the coni vasculosi in the upper part of the epididymis, still more doubt has pre-
vailed. Since Mailer's discovery in birds of the collateral duct named after him, and
the extension of this discovery to mammals, it has been customary to regard the
upper part of the epididymis as produced by a transformation of the tubes and duct
in the upper part of the Wolffian body, according to the views most fully given by
Kobelt ; but doubts have been entertained by some as to the correctness of this view,
and more recent observations by Banks appear to prove that it must, in some degree,
be modified.
According to Banks, the origin of the coni vasculod is due to a process of develop-
ment occurring in a new structure or mass of blastema which had been previously
observed by Cleland, and which is deposited at the upper end of the Wolffian body,
and close to the Mullerian duct. Within this blastema Cleland showed that the tubes
of the efferent seminal vessels and the coni vasculosi, together with the tube which
connects them, are formed anew, while the tubes of the adjacent part of the Wolffian
body are undergoing an atrophic degeneration. This has been confirmed by the de-
tailed observations of Banks, who has further shown the continuity of their uniting
tube with the Wolffian excretory duct.
Should this view prove to be correct, the caput epididymis must be regarded not
simply as a conversion of the upper part of the Wolffian body, but rather as a new
formation or superinduced development in blastema connected with it.
The coni vasculosi, so formed, become connected with the body of the testicle by
means of a short straight cord, which is afterwards subdivided into the vasa efferentia.
The peritoneal elevation descending from the testis towards the lower extremity of the
Wolffian body, is the upper part of the plica gubernatrix, and becomes shortened as
the testicle descends to meet the lower end of the epididymis ; the peritoneal elevation
which passes down into the scrotum, and is continuous with the other, is the more
important part of the plica gubernatrix, connected with the gubernaculum testis.
The spermatic artery is originally a branch of one of those which go to the
Wolffian body, and ascends from the surface of the Wolffian body to the upper part of
the testis, along the ligaments connecting them ; but, as the testis descends, the artery
lies entirely above it, and the secreting substance of the Wolffian body remains adherent to
it ; and hence it is that the organ of Giraldes, which consists of persistent Wolffian
tubules, is found in a position superior to the epididymis. (For a fuller account
of this complicated subject the student is referred to Banks " On the Wolffian
Bodies." Edin. 1864.)
The descent of the testicles is a term applied to the passage of the testes from the
abdominal cavity into the scrotum. The testicle enters the internal inguinal ring in
the seventh month of foetal life : by the end of the eighth month it has descended
into the scrotum, and, a little time before birth, the narrow neck of the peritoneal
pouch, by which it previously communicated with the general peritoneal cavity,
becomes closed in the manner elsewhere described (p. 965), and the proeess of peri-
toneum, now entirely shut off from the abdominal cavity, remains as an independent
serous sac. The peritoneal pouch, or processus vaginalis, which passes down into the
scrotum, precedes the testis considerably in its descent, and into its posterior part
there projects a considerable columnar elevation already alluded to, which is filled
with soft tissue, and is termed plica ffubernafrix. There is likewise a fibrous struc-
1000
DEVELOPMENT OF THE GENERATIVE OEGANS.
ture attached inferiorly to the lower part of the scrotum, and surrounding the peri-
toneal pouch above, which may be distinguished as the gubernacular cord, both this
and the plica gubernatrix being included in the general term gubernaculum testis
(J. Hunter). The gubernacular cord consists ef fibres which pass downwards from
the sub-peritoneal fascia, others which pass upwards from the superficial fascia and
integument, and others again which pass both upwards and downwards from the
internal oblique muscle and the aponeurosis of the external oblique ; it exhibits,
therefore, a fusion of 'the layers of the abdominal wall. Superiorly, it surrounds
the processus vaginalis, without penetrating the plica gubernatrix; and the pro-
cessus vaginalis, as it grows, pushes its way down through the gubernacular cord and
disperses its fibres. By the time that the testis enters the internal abdominal ring,
the prccessus vaginalis has reached a considerable way into the scrotum ; and, as the
testis follows, the plica gubernatrix becomes shorter, till it at last disappears; but it
cannot be said that the shortening of the plica is the cause of the descent of the
testicle, and much less (as has been held by some) that the muscular fibres of the
gubernacular cord are the agents which effect this change of position. The arched
fibres of the cremaster muscle make their appearance on the surface of the processus
vaginalis as it descends, while its other fibres are those which descend in the guber-
nacular cord. (See for a further account of this process, and the various views which
have been held with regard to the descent of the testicles, Cleland, " Mechanism of
the Gubernaculum Testis." Edinburgh, 1856.)
The External Organs of Generation. — In the human subject, these have for some
time the same form in both sexes ; but, in animals in which the penis is prolonged to
the umbilicus, that circumstance forms one of the very earliest sexual distinctions,
inasmuch as the clitoris hangs free.
Fig. 695. — DEVELOPMENT OP THE EX-
TERNAL SEXUAL ORGANS IN THE MALE
AND FEMALK FROM THE INDIFFERENT
TYPE (from Ecker).
A, the external sexual organs in an
embryo of about nine weeks, in which
sexual distinction is not yet established,
and the cloaca still exists : B, the same
in an embryo somewhat more advanced,
and in which, without marked sexual
distinction, the anus is now separated
from the urogenital aperture : C, the
same in an embryo of about ten weeks,
showing the female type : D, the same
in a male embryo somewhat more ad-
vanced. Throughout the figures the
following indications are employed; pct
common blastema of penis or clitoris ;
to the right of these letters in A, the
umbilical cord ; p, penis ; c, clitoris ; cl,
cloaca; ug, urogenital opening; a, anus;
I s, cutaneous elevation which becomes labium or scrotum ; I, labium ; s, scrotum ; c 0,
coccygeal elevation.
Up to the fifth week, according to Tiedemann, there is no separate genito-urinary
orifice, and indeed no anus. Previous to this period, or about the beginning of the
fourth week, there is a common opening, for the intestine, the generative, and the
urinary organs, i. e., a cloacal aperture. In front of this simple opening, there soon
appears a small recurved projecting body, which, as it enlarges, becomes grooved
along the whole of its under surface. This is the rudimentary clitoris, or penis, at
the summit of which an enlargement is formed which becomes the glans. The
margins of the groove seen on its under surface are continued backwards on each
side of the common aperture, which is now elliptical, and is bounded laterally by
two large cutaneous folds. Towards the tenth or eleventh week a transverse band,
the commencing perinceum, divides the anal orifice from that of the genito-urinary
passage, which latter now appears as a rounded aperture, placed below the root of
C.
D.
FORMATION OF THE EXTERNAL ORGANS. 1001
the rudimentary clitoris or penis, and between the prolonged margins of the groove
beneath that organ. This opening, but not the clitoris or penis, is concealed by the
large cutaneous folds already mentioned. In this condition, which continues until
the twelfth week, the parts appear alike in both sexes, and resemble very much the
perfect female organs. The rudiments of Cowper's (/lands are, it is said, seen at an
early period, near the root of the rudimentary clitoris or penis, on each side of the
genito-urinary passage.
In the female, the two lateral cutaneous folds enlarge, so as to cover the clitoris
and form the labia majora. The clitoris itself remains relatively smaller, and the
groove on its under surface less and less marked, owing to the opening out and sub-
sequent extension backwards of its margins to form the nymphce. The hymen begins
to appear about the fifth month. Within the nymphae, the urethral orifice, as
already mentioned, becomes distinct from that of the vagina.
In the male, on the contrary, the penis continues to enlarge, and the margins of
the groove along its under surface gradually unite from the primitive urethral
orifice behind, as far forward as the glans, so as to complete the long canal of the
male urethra. This is accomplished about the fifteenth week. When this union
remains incomplete, the condition named hypospadias is produced. In the mean-
time the prepuce is formed, and, moreover, the lateral cutaneous folds also unite
from behind forwards, along the middle line or raphe, and thus complete the scrotum,
into which the testicles do not descend until the last month of foetal existence.
The following tabular scheme of the corresponding parts of the genito-
urinary organs in the two sexes, and of their relation to the formative
rudiments of the common embryonic type, may be useful in fixing attention
on the more important points of the subject.
FEMALE. COMMON EMBRYONIC. MALE.
Ovai7 ........ • I71S3am°n. . .repr0dUCtiTe } Body of Testicle.
II.— Wolffian body.'
Irregular vestiges near paro- \ 2. Tubular substance of j Organ of Giralde"s.
varium (?) .................. ) the gland ............ \ Vasa aberrautia.
Duct of Gaertnerinsomeani-) f3" *g^d duct along ^^ ^ rf mig>
mals ...................... ' (4. Duct below the gland Vas deferens.
III.— Duct of Mtiller.
FlmM. and FaUopian tube . . !. Ujjp. ^and^part ) Hyd,tM -HjgjjP- «d other
gland .............. )
Cornu uteri .................. 2. Free part of duct . . . . { C°™^m°lsimiS P°CUlar
Uterus and vagina ............ 3. Fused part of both \
ducts in the genital j- Sinus pocularis.
cord .............. )
Female urethra .............. I V. -Pedicle of the allantois ..{ UpPJJ Pr°e?£a °f pl'°StatiC P&rt
Vestibule .................... V.-Sinus urogenii.lis ........ {
Glands of Bartholin .......... Common blastema ............ Glands of Cowper.
VI. — Common sexual pro-
minence and integumental
folds.
Corpora cavemosa clitoridis . . 1. Common blastema ____ Corpora cavemosa penis.
Labia majora ................ 2. Outer integumental \ gcrotum
Nymphse ................... 3. Inner integumental ) Integument of lower surface of
folds ................ j penis.
Vestibular bulbs and other erec- ) 4. Common blastema j Bulb and corpus spongiosum
tile tissue .................. ) " \ urethrse.
VII.— Peritoneal folds and
gubernacular bands.
Canal of Nuck ................ 1. ^f^l peritoneal j. Processu8 vagilialis.
Ovarian ligament ............ *-lS tetet" J^l«-" connecting testicle and
nan body .............. j globus minor.
Round ligament of uterus .... 3. Band rom } Gubernaculum testi-.
1002 THE MAMMARY GLANDS.
MAMMARY GLANDS.
The mammary glands (mammae), the organs of lactation in the female,
are accessory parts to the reproductive system. They give a name to a
large class of animals (Mammalia), which are distinguished by the possession
of these organs. When fully developed in the human female, they form,
together with the integuments and a considerable quantity of fat, two
rounded eminences (the breasts) placed one at each side on the front of the
thorax. These extend from the third to the sixth or seventh rib, and from
the side of the sternum to the axilla. A little below the centre of each
breast, on a level with the fourth rib, projects a small conical body named the
nipple (mammilla), which points somewhat outwards and upwards. The sur-
face of the nipple is dark, and around it there is a coloured circle or areola,
within which the skin is also of a darker tinge than elsewhere. In the
virgin, these parts are of a rosy pink colour, but they are always darker in
women who have borne children. Even in the second mouth of pregnancy,
the areola begins to enlarge and acquire a darker tinge ; these changes go
on increasing as gestation advances, and are regarded as reliable sigus in
judging of suspected pregnancy. After lactation is over, the dark colour
subsides, but not entirely. The skin of the nipple is marked with many
wrinkles, and is covered with papillae ; besides this, it is perforated at the
tip by numerous foramina, which are the openings of the lactiferous ducts :
and near its base, as well as upon the surface of the areola, there are scat-
tered rounded elevations, which are caused by the presence of little glands
with branched ducts, four or five of which open on each elevation. The
tissue of the nipple contains a large number of vessels, together with much
plain muscular tissue, and its papillae are highly sensitive ; it is capable of
a certain degree of erection from mechanical excitement, which may be
partly caused by turgescence of its vessels, but is probably due, in greater
part, to contraction of the muscular fibres.
The base of the mammary gland, which is nearly circular, is flattened,
or slightly concave, and has its longest diameter directed upwards and
outwards towards the axilla. It rests on the pectoral muscle, and is con-
nected to it by a layer of areolar tissue. The thickest part of the gland
is near the centre, opposite the nipple, but the full and even form of the
breasts depends chiefly on the presence of a large quantity of fat, which
lies beneath the skin, covers the substance of the gland, and penetrates the
intervals between its lobes and lobules. This fatty tissue, which is of a
bright yellow tinge and rather firm, is divided into lobulated masses by
numerous laminae of fibrous or very dense areolar tissue, which are con-
nected with the skin on the one hand, and on the other with the firm
areolar investment of the gland itself, which investment is connected behind
by similar laminae with the areolar membrane covering the pectoral muscle ;
these laminae serve to support the gland. Beneath the areola and the
nipple there is no fat, but merely the firm areolar tissue and vessels sur-
rounding the lactiferous ducts.
Structure. — The mammary gland consists of a number of distinct
glandular masses or lobes, each having a separate excretory duct, held
together by a very firm intervening fibrous or areolar tissue, and having
some adipose tissue penetrating between them. Each of these divisions of
the gland is again subdivided into smaller lobes, and these again into
smaller and smaller lobules, which are flattened or depressed, and held
together by areolar tissue, blood-vessels, and ducts. The substance of the
STEUCTUEE OF THE MAMMA.
1003
lobules, especially as contrasted with the adjacent fat, is of a pale, reddish
cream-colour, and is rather firm. It is composed principally of the vesi-
cular commencements of the lactiferous ducts, which appear like clusters of
minute rounded cells, having a diameter from ten to thirty times as great
Fig. 696.
Fig. 696.— DISSECTION OP THE LOWER HALF OF THE FEMALE MAMMA DURING THE
PERIOD OF LACTATION (from Luschka). f
In the left-hand side of the dissected part the glandular lobes are exposed and partially
unravelled ; and in the right-hand side, the glandular substance has been removed to
show the reticular loculi of the connective tissue in which the glandular lobules are
placed : 1 , upper part of the mammilla ; 2, areola ; 3, subcutaneous masses of fat ;
4, reticular loculi of the connective tissue which support the glandular substance and con-
tain the fatty masses ; 5, one of three lactiferous ducts shown passing towards the
mammilla where they open ; 6, one of the sinus lactei or reservoirs ; 7, some of the
glandular lobules which have been unravelled ; 7', others massed together.
as that of the capillary vessels by -which they are surrounded. These cells
open into the smallest branched ducts, which, uniting together to form
others of larger size, finally end in a single excretory canal correspond-
ing to one of the chief subdivisions of the gland. The canals proceeding
thus from the principal lobes composing the gland are named the galacto-
phorous ducts, and are from fifteen to twenty in number ; they converge
towards the areola, beneath which they become considerably dilated, espe-
cially during lactation, so as to form sacs or sinuses two or even three lines
wide, which serve as temporary though small reservoirs for the milk. At
the base of the nipple all these ducts, again reduced in size, are assembled
together, those in the centre being the largest, and then proceed side by
side, surrounded by areolar tissue and vessels, and without communicating
with each other, to the summit of the mammilla, where they open by sepa-
rate orifices ; these orifices are seated in little depressions, and are smaller
than the ducts to which they respectively belong. The walls of the ducts are
composed of areolar tissue, with longitudinal and circular elastic filaments.
1004
THE MAMMARY GLANDS.
The mucous membrane is continuous with the common integument at the
orifices of the ducts ; its epithelium is scaly or tesselated, and in the
smallest ducts and their ultimate vesicles consists of cells having a diameter
very little exceeding that of their nuclei.
Fig. 697.
Fig. 697. — MAGNIFIED VIEWS OP THE GLANDULAR SUBSTANCE OP THE MAMMA DURINQ
THE PERIOD OP LACTATION (from Henle).
A, section of a small lobule of the gland, magnified 60 diameters; 1, stroma of connec-
tive tissue supporting the glandular tissue ; 2, terminal ramuscule of one of the gland-
tubes ; 3, glandular vesicles.
B, four glandular vesicles magnified 200 diameters, showing the lining ^epithelial cells
and some milk-globules within them.
Blood-vessels and Nerves. — The arteries which supply the mammary glands are
the long thoracic and some other branches of the axillary artery, the internal mam-
mary, and the subjacent intercostals. The veins have the same denomination.
Haller described a sort of anastomotic venous circle surrounding the base of the
nipple as the circidus venosus. The nerves proceed from the anterior and middle
intercostal cutaneous branches.
In the male, the mammary gland and all its parts exist, but quite in a
rudimentary state, the gland itself measuring only about six or seven lines
across, and two lines thick, instead of four inches and a half wide and one
and a half thick, as in the female. Occasionally the male mamma, espe-
cially in young subjects, enlarges and pours out a thin watery fluid ; and,
in some rare cases, it has secreted milk.
Varieties. — Two or even three nipples have been found on one gland. An addi-
tional mamma is sometimes met with, and even four or five have been observed to
co-exist ; the supernumerary glands being most frequently near the ordinary pair,
but sometimes in a distant part of the body, as the axilla, thigh, or back.
DIVISION II.
SUEGICAL ANATOMY.
I.— SURGICAL ANATOMY OF THE ARTERIES.
IN the description of the several blood-vessels, the points bearing on
operative surgery have been indicated in detail. The leading facts to be
attended to by the surgeon in the operation of placing a ligature on the
chief arterial trunks will be now collectively considered.*
SURGICAL ANATOMY OF THE COMMON CAROTID ARTERY.
The common carotid artery does not furnish any branch, save in very
rare instances. In a practical or surgical point of view, the branches arising
sometimes close to its upper end may be disregarded, so that a ligature can
be applied to any part of the vessel, except immediately at its commence-
ment or termination. When the case is such as to allow a choice, the point
which combines the most favourable circumstances for the operation, is
opposite the lower end of the larynx. Here a large space would, in ordi-
nary cases, intervene between the ligature and the ends of the vessel ; and
at the same time this part is free from the difficulties offered by the muscles
lower down, and by the superior thyroid veins, if the artery be secured near
its bifurcation. But it has been shown (p. 345) that the carotid artery
occasionally bifurcates below the usual position — opposite the lower margin
of the larynx, and even, however rarely, lower than this. In such cases,
should the artery be laid bare at the point of division, it would be best to
tie the two parts separately, close to their origin, in preference to tying the
common trunk near its end. If, in consequence of very early division of
the common carotid or its entire absence (cases which, however, are of ex-
tremely rare occurrence), two arteries (the external and internal carotids)
should happen to come into view in the operation supposed, the most judi-
cious course would doubtless be to place the ligature on that artery, which,
upon trial, as by pressure, should prove to be connected with the disease.
In performing the operation, the direction of the vessel and the inner
margin of the stern o-mastoid muscle are the surgeon's guides for the line of
incision!1. Before dividing the integument it is well to ascertain whether the
anterior jugular vein be in the line of incision. Should the operation be per-
formed at the lower part of the neck, some fibres of the muscles will require to
be cut across in order to lay the artery bare with facility ; and the necessity
for this step increases in approaching towards the clavicle. After the super-
* The plates referred to in this section are those of Richard Quain " On the Arteries."
1006
SURGICAL ANATOMY OF THE ARTERIES.
ficial structures have been divided, assistance will be derived from the
trachea or the larynx, as well as from the pulsation, in determining the
exact situation of the artery. The trachea, from its roughness, may be
Fig. 698.
Fig. 698. — VIEW OP THE RIGHT COMMON CAF.OTID AND SUBCLAVIAN ARTERIES, WITH
THE ORIGIN OF THEIR BRANCHES AND THEIR RELATIONS (from R. Quain). ^
e, front of the hyoid bone ; /, thyroid cartilage ; g, isthmus of the thyroid gland ; 7i,
the trachea above the inter-clavicular notch of the sternum ; i, i\ the sawn ends of the
clavicle, the portion between them having been removed ; &, the first rib ; in, sealemis
medius; p, on the longus colli muscle, pointing to the pneumogastric nerve; IV, the
uppermost of the nerves of the axillary plexus ; A, the innominate artery ; 1, right
common carotid artery ; 1', placed on the left sterno-thyroid muscle, points to a part of
the left common carotid ; 2, internal carotid ; 2', upper part of the internal jugular vein,
which has been removed between i, and 2' ; 3, and 4, external carotid ; 3, is placed at
the origin of the superior thyroid artery ; 4, at that of the lingual ; 5, the superior
thyroid artery ; 5', the thyroid or glandular branch ; 8, the first part, 8', the third part
of the arch of the subclavian artery ; 8", the subclavian vein separated from the artery
by the scalenus anticus muscle; 9, is placed on the scalenus anticus rauscle in the angle
between the transversalis colli and suprascapular branches of the thyroid axis; 10,
SUBCLATIAN AETERIES. 100?
outer part of the supra-scapular artery ; 10', transverse cervical "branches passing into
the deep surface of the trapezius ; 10", the posterior scapular artery, represented as
rising directly from the third part of the subclavian artery, and passing through the
axillary plexus of nerves and under the levator anguli scapulas ; 11, on the scalenus
anticus muscle, points to the inferior thyroid artery near the place where the ascending
muscular artery of the neck is given off; the phrenic nerve lies on the muscle to the
outside ; at i, the suprasternal twig of the suprascapular artery is shown.
retdily felt in the wound, even while the parts covering it have still some
thickness. The sheath of the vessels is to be opened over the artery — near
the trachea — for thus the jugular vein is most easily avoided. This vein,
should it lie in front of the artery, as it sometimes does on the left side, and
especially at the lower part of the neck on that side, will be a source of
much difficulty in completing the operation, i. e., in passing the aneurism,
needle with the ligature about the artery. To surmount the difficulty much
caution is required. The operator will find it advantageous to have the
circulation in the vein (which in such operations becomes turgid and very
large) arrested at the upper end of the wound by means of an assistant's
finger. In most cases, if not in all, it is best to insert the aneurism needle
conveying the ligature on the outer side of the artery, for thus the vagus
nerve and the jugular vein will be most effectually avoided.
SURGICAL ANATOMY OF THE SUBCLAVIAN ARTERIES.
The subclavian artery is so deeply placed, its connections with important
parts are so intimate and varied, and the branches are so large in proportion
to the length of the trunk, that operations on this vessel present, in most
cases, considerable difficulties to the surgeon. But the difficulties, it will be
found, vary in different cases.
The last division of the artery, that beyond the anterior scalenus muscle
(p. 366), is the part which is most favourably circumstanced for the applica-
tion of a ligature in the case in which such an operation is most frequently
called for, namely, aneurism affecting the artery in the axilla. This part is
preferable chiefly because the vessel is here nearest to the surface, and most
remote from the origin of the large branches. But, though the subclavian
artery appears to be easy of access above the clavicle while the parts are in
their natural position, it is to be remembered that, when an aneurism exists
in the axilla, the clavicle may be so much elevated in consequence of the
presence of the tumour, as to be placed in front of the vessel, or even above it.
In such circumstances, the artery lies at a great depth, and at the same time
the structures in front and behind it (the clavicle on the one hand, the vertebrae
with the muscles covering them on the other hand), cannot, in any degree, be
drawn asunder to facilitate the steps of the operation. It is when the outer
part of the clavicle is thus raised from the ordinary horizontal position, that
the height to which the artery arches above the bone becomes a point of im-
portance. In most cases it happens that a portion of the artery is a shorb
distance (about an inch) above the clavicle [plate 3] ; but occasionally, as
before mentioned (p. 367), it rises much higher [plate 20, fig. 3]; or it may
be lower than usual, lying close behind the bone [fig. 2]. If, in a case ren-
dering the operation necessary, the clavicle should be unusually raised, the
accessibility of the vessel in the neck will differ in these several conditions :
in one, the artery could be arrived at only by proceeding from above down-
wards behind the bone : in another, a part of it would still be higher than
the bone. This will serve, in part at least, to account for differences in the
time which the operation for tying the subclavian artery has occupied in the
1008 SURGICAL AXATOMY OF THE ARTERIES.
hands of different surgeons, and even in the hands of the same surgeon in
different cases.*
The principal facts bearing on the actual performance of an operation on
the third part of the subclaviau artery, will now be briefly recalled. The
most prominent or convex part of the clavicle, the part of the bone opposite
which the vessel lies, will serve as a guide for the middle of the first incision,
which is to be made a little above the clavicle, and parallel with it. If
(after noting with the eye, or marking on the surface the line at which it is
desired to make the incision), the integument be drawn downwards over the
clavicle, the parts covering the bone may be divided with freedom.
With the integument, the platysma and several nerves are divided in thi^t
incision, but no vessel is endangered, except in those rare cases in which the
cephalic vein or the external jugular crosses over the clavicle [plate 25,
figs. 4, 5]. It will, in most cases, be an advantage to add a short vertical
incision, directed downwards to the middle of the horizontal one. Should
the sterno-mastoid muscle be broad at its lower end, or should the interval
between that muscle and the trapezius be insufficient for the farther steps of
the operation, a portion of the former muscle, or even of both muscles, must
be divided [plate 25, fig. 7].
The external jugular vein next presents itself with the veins joining it
from the shoulder, and, as this vein is usually over the artery, it must be
held aside, or it may be necessary to divide it. If divided, the lower end of
the vessel requires the application of a ligature as well as the upper one, iti
consequence of the reflux of blood from the subclaviau vein. The omo-hyoid
muscle will be turned aside if necessary ; and now must be determined the
exact position at which the artery is to be sought by division of the deeper
fascia. If the clavicle have its usual horizontal direction, the first rib is the
best guide to the vessel. The brachial nerves are here, it is to be remem-
bered, close to the vessel, — so much so, that the ligature has in several
cases been passed in the first instance round one of them instead of the
artery. But if, in consequence of the disease rendering the operation neces-
sary, the outer end of the clavicle be much raised, then it will, in many
cases, be more easy to place the ligature on the artery above the insertion of
the scalenus muscle, or even behind that muscle. Above the first rib, the
situation of the vessel may be ascertained by means of the brachial nerves
and the scalenus muscle ; and, before the membrane covering them is
divided, the position of these structures may be ascertained by the difference
they offer to the touch. The cord-like nerves and the smooth flat muscle
may thus be readily distinguished. At the same time the influence of
pressure at a particular point in controlling the pulsation in the aneurism,
will in this, as in other operations on the arteries, assist the surgeon.
* This statement will be illustrated by reference to two cases which, occurred at nearly
the same time in the practice of the same surgeon. In March, 1819, M. Dupuytren tied
the subclaviau artery for axillary aneurism, and the result was in all respects favourable.
—See "Le9ons orales," &c., t. iv.; and M. Marx in "Repert. general d'anatoinie," &c.
1826.
Two or three weeks afterwards the same surgeon, being engaged in performing an
operation of the same kind, was compelled to discontinue it for a time in consequence of
the sufferings of the patient, and an hour and forty-eight minutes elapsed before the
operation was concluded. The patient died of haemorrhage in four days ; and, on exami-
nation after death, it was found that the artery had been perforated with the aneurism
needle. One of the large nerves and half the artery had been included in the ligature.
This case is reported by Dr. Rutherford, R.N., who was present at the operation, in
"Edinburgh Med. and Surg. Journal," vol. xvi. 1820.
SUBCLAVIAN ARTERIES. LIGATURE. 1009
Before concluding the remarks on the third division of the artery, it should
be mentioned that the suprascapular or transverse cervical artery may be
met with in the operation, which in other cases may be complicated by the
occurrence of a branch, or, however rarely, of branches, taking rise beyond
the scalenus muscle.
The second division of the subclavian artery is the part which rises highest
in the neck, and on this account it may be advantageously selected for the
application of a ligature when the vessel is difficult of access beyond the
muscle. The chief objection to operating on the artery in this situation
arises from the contiguity of the large branches. Care is necessary in
dividing the scalenus muscle to avoid the phrenic nerve and the internal
jugular vein. Moreover, the fact of the entire of the subclavian artery
being in apposition with the pleura, except where it rests on the rib, must
be borne in mind.
Some difficulty may arise from a change in the position of the artery, as
when it lies between the fibres of the anterior scalenus, or when it is in
front of that muscle ; but such cases are of very rare occurrence, and the
knowledge of the fact that the vessel may be thus displaced, will assist the
surgeon in the event of difficulty arising from this cause.
Before it reaches the scalenus muscle the left subclavian artery [plate 2]
may be said to be inaccessible for the application of a ligature, in consequence
of its depth and its close connection with the lung and other structures cal-
culated to create difficulty in an operation, among which may be mentioned
the internal jugular and left innominate veins. To the difficulties resulting
from the manner of its connection with the parts now named, must be
added the danger of performing an operation in the neighbourhood of the
large branches.
On the right side, though deeply placed and closely connected with im-
portant parts, the first division of the subclavian artery may be tied with-
out extreme difficulty. But inasmuch as the length of the vessel, between
its three large branches on the one hand, and the common carotid on the
other, ordinarily measures no more than an inch, and often less, there is
little likelihood of the operation in question being successfully performed in
any case ; and the probability of success must be held to be still farther
diminished when it is considered that the length of the free part of the
artery is sometimes lessened by one of the large branches arising nearer than
usual to its commencement.
In order to place a ligature on the portion of the right subclaviau artery
here referred to, it is necessary to divide by horizontal incisions the
three muscles which cover it, together with the layers of fascia between and
beneath them [plate 17, fig. 1]. While the muscles are being divided, a
branch of the suprascapular artery will probably require to be secured
[plate 16]. The position of the inner end of the clavicle and of the trachea,
and the effect of pressure with the finger on the circulation in the aneurism
or in the limb, will assist the surgeon in finding the artery without dissect-
ing the surrounding parts to an unnecessary and injurious extent — a pre-
caution of importance in all cases. In the farther steps of the operation,
the exact position of the internal jugular vein, the vagus nerve, and the
pleura, are to be well remembered.
The right subclavian artery is occasionally somewhat more deeply placed
than usual in the first part of its course : and this occurs when it springs
from the left side of the arch, or, more frequently, when it separates from
the innominate behind the carotid [plate 20, fig. 4],
3 u
1010
SURGICAL ANATOMY OF THE ARTERIES.
SURGICAL ANATOMY OF THE BRACHIAL ARTERY.
In the operation for tying the brachial artery, the known direction of the
vessel, and the inner margin of the biceps muscle, chiefly aid in determining
its position (p. 382). In consequence of the thinness of the parts which
cover the artery, and the position of the basilic and median basilic veins
with respect to it, even the integuments must be divided with care. After
turning aside the superficial vein, should that be necessary, and dividing the
fascia, the median nerve will probably come into view, and the artery will
then be readily found. This is the course required under ordinary circum-
stance?. But it may happen that, after dividing the fascia, it will be neces-
sary to cut through a layer of muscular fibres in order to bring the artery
into view [plate 37, figs. 3, 4, 6]. The influence of pressure with the
finger, in controlling the circulation, will enable the surgeon to determine if
Fig. 699.
Fig. 699. — DISSECTION OF THE AXILLA AND INSIDE OF THE ARM TO SHOW THE
AXILLARY AND BRACHJAL VESSELS (from R. Quain). £
The greater and lesser pectoral muscles have been divided so as to expose the axillary
vessels : a, the inserted portion of the pectoralis major ; b, the pectoral portion ; 1, 1,
axillary artery ; +,-(-, the median nerve formed by the two portions of the plexus which
surround the artery ; 1', placed on a part of the sheath of the brachial vessels, and 1", on
the lower part of the biceps muscle, point to the brachial artery surrounded by its venae
comites ; 2, 2, axillary vein ; 3, 3, the basilic vein ; the upper figure is placed on the
triceps muscle, the lower on the fascia near the junction of the ulnar vein : on the basilic
vein are seen the ramifications of the internal cutaneous nerve ; 4, on the deltoid and 4',
on the clavicular part of the great pectoral muscle, mark the cephalic vein joining the
acromio -thoracic and through it the axillary vein; 5, 5, placed on the divided portions of
the pectoralis minor, point to the origin and branches of the acromio-thoracic artery ; 6,
placed on a group of axillary glands, indicates the alar thoracic and subscapular vessels ;
7, placed on the trunk of the axillai-y vein, points by a line to one of the venae coraites of
the brachial vein, which being joined by the other higher up passes into the axillary vein :
the ulnar nerve is seen passing from below the basilic vein towards the inner condyle ;
near 1, placed on the coraco-brachialis muscle is seen the musculo-cutaneous nerve before
it passes through that muscle.
BRACIIIAL ARTERY.
1011
the vessel be behind the muscular fibres, and will guide him to the place at
which they ought to be divided.
Again, as the brachial artery occasionally deviates from its accustomed
place in the arm, it is prudent, before beginning an operation on the living
body, to be assured of its position by the pulsation. Should the vessel be
thus displaced, it has the ordinary coverings of the brachial artery, except at
the lower part of the arm, where some fibres of the pronator teres will re-
quire to be divided in an operation for securing the vessel.
When the brachial artery is double, or when two arteries are present in
the arm, both being usually placed close together, they are accessible in the
same operation. The circumstance of one being placed over the fascia
(should this very unfrequent departure from the usual arrangement exist)
will become manifest in the examination which ought to be made in all cases
before an operation is begun. And, as regards the occasional position of one
of the two arteries beneath a stratum of muscular fibres, or its removal to
the inner side of the arm (in a line towards the inner condyle of the hume-
rus), it need only be added that a knowledge of these exceptional cases will
at once suggest the precautions which are necessary, and the steps which
should be taken when, they are met with. — The foregoing observations have
reference to operations on the brachial artery, above the bend of the elbow ;
the surgical anatomy of the vessel opposite that joint requires a separate
notice.
Fig. 700.
Fig. 700. — SUPERFICIAL DISSECTION OF THE
BLOOD-VESSKLS AT THE BEND OP THE ARM
(from R. Quain). £
a, two branches of the internal cutaneous
nerve ; a', a', the descending twigs of the same
nerve ; &, placed over the biceps near its in-
sertion and close to the external cutaneous nerve ;
&', anterior twigs of the same nerve accompany-
ing the median vein ; 1, placed on the fascia
near the bend of the arm, above the place where
it has been opened to show the lower part of the
brachial artery with its venae comites, of which
one is entire, marked 2, and the other has been
divided ; +, is placed between this and the
median nerve ; 3, basilic vein ; 3', 3', ulnar
veins ; 4, cephalic vein ; 4', radial vein ; 5, 5,
median vein ; 3', 5, median basilic vein ; 4', 5,
median cephalic vein.
At the bend of the elbow the disposition
of the brachial artery is chiefly, or, at
least, most commonly, of interest in a
surgical point of view, because of its con-
nection with the veins from which blood
is usually drawn in the treatment of
disease. The vein (median basilic) which
is generally the most prominent and
apparently best suited for venesection
is commonly placed over the course of
the brachial artery, separated from it
only by a thin layer of fibrous structure (the expansion from the tendon of
the biceps muscle) ; and under such circumstances, it ought not, if it can be
3 u 2
1012 SURGICAL ANATOMY OF THE ARTERIES.
avoided, to be opened with a lancet, except in a part which is not contiguous
to the artery.
When two arteries are present, instead of the ordinary single trunk, they
are commonly close together ; but it now and then happens that an interval
exists between them — one being in the usual situation of the brachial, the
other nearer, in different degrees in different cases, to the inner condyle of
the humerus. There is on this account an additional reason for precaution
when venesection is to be performed ; and care is the more necessary, as the
second artery may be immediately under the vein without the interposition
of fascia [plate 41].
SURGICAL ANATOMY OF THE COMMON ILIAC ARTERIES.
The common iliac artery (p. 418), extending in a line from the left side
of the umbilicus towards the middle of Poupart's ligament, and being placed
at its commencement on a level with the highest part of the iliac crest, may
be approached in an operation, by dividing the abdominal muscles to a
sufficient extent in the iliac region, and a little above this part of the abdo-
men. The incision may be made, beginning about Poupart's ligament,
to the outer side of its middle, and running parallel with that structure
towards the anterior superior spine of the hip-bone, thence curving for a
couple of inches towards the umbilicus. In this way the artery will be ap-
proached from below, but, if a tumour extends along the external iliac
artery, this plan of operation will be objectionable, for the swelling itself,
and, it may be, the adhesion of the peritoneum to its surface, will be
sources of serious difficulty. Should the aneurism extend upwards iu the
abdomen it will be best to approach the artery from the side, or rather
from above, — not from below. The essential part of the operation, so far as
the abdominal muscles are concerned, is, that they should be divided to the
extent of five or six inches at the side of the abdomen, beginning about
two inches above the level of the umbilicus and ending lower than the
iliac spine, the incision being curved outwards towards the lumbar region.
Sir P. Crampton, in an operation to tie this artery, divided the muscles from
the end of the lowest rib, straight down nearly to the iliac crest, and thence
forward a little above the border of the bone as far as its spine. * This plan
is well devised for the object.
The fascia behind the muscles (fascia transversalis) is to be cut through
with care, and the peritoneum is to be raised from that and the iliac fascia,
as well as from the subjacent membrane (sometimes containing fat) which is
interposed between the serous and the fibrous membranes. With the peri-
toneum the ureter will be raised, as this adheres to it.
The artery will be seen on the last lumbar vertebra ; and, on the right
side of the body, large veins will be in view in close connection with it,
viz., both common iliac veins, and the commencement of the lower
vena cava [plate 55]. It will be remembered, that in some cases (with-
out transposition of the viscera, as well as with that condition) the iliac
veins are joined on the left instead of the right side; and that in
another small class of cases the junction of those veins is delayed, so to
say [plate 58, figs. 1, 2, 3]. The effect of either of these conformations of
the venous system would be to give to the artery on the left side much
more than the usual complication with veins. Lastly, the thin subserous
membrane covering the artery is divided without any difficulty, to admit
the passage of the ligature.
* Med. Chir. Trans., vol. xvi.
COMMON ILIAC ARTERIES.
1013
The common iliac artery is in most cases of sufficient length to admit
the application of a ligature without much apprehension of secondary
haemorrhage occurring in consequence of insufficiency in this respect. But
Fig. 701.— VIEW OP Figi 701.
THE BIGHT EXTER-
NAL AND INTERNAL
ILIAC ARTERIES OF
THE MALE. ^
The viscera of the
pelvis have been re-
moved as well as the
internal iliac veins.
1, lower part of the
abdominal aorta ; 1',
middle sacral artery ;
2, 2, common iliac ar-
teries ; 2', right exter-
nal iliac ; 3, lower
part of the vena cava
inferior ; 4, 4, com-
mon iliac veins ; the
number on the right
points by a line to the
right internal iliac
artery; 4', right ex-
ternal iliac vein ; 5,
placed on the ilio-
lumbar nervous trunk,
points to the posterior
division of the internal
iliac artery giving off
the gluteal; 5', ilio-
lumbar artery ; 5",
lateral sacral artery
with branches passing
into the anterior sacral
foramina ; 6, placed
on the anterior divi-
sion of the first sacral
nerve, points to the
sciatic artery coming from the anterior division of the internal iliac ; 7, pudtc artery ; 7',
the same artery passing behind the spine of the ischium, and proceeding within the
ischium and obturator internus muscle, accompanied by the pudic nerve towards the
peringeum ; towards /, inferior hremorrhoidal branches are given off ; 7", superficial
perineal artery and nerve; 8, hypogastric artery, with the obliterated remains of the
umbilical artery cut short, and 8', superior vesical branches rising from it : 9, obturator
artery with the corresponding nerve and vein; 9', the pubic twigs which anastomose
with descending twigs of the epigastric artery, and from which, by the enlargement of
one of them, the aberrant obturator artery may proceed ; 10, inferior vesical ; 11, middle
haemorrhoidal vessels rising in this instance from the pudic ; 12, epigastric artery winding
to the inside of +, +, the vas deferens and spermatic cord ; 13, circumflex iliac artery ;
14, spermatic artery and vein divided superiorly ; 15, twigs of the ilio-lumbar artery
proceeding to anastomose with the circumflex iliac.
it has been shown (p. 420) to be in some instances very short — so short
that the operation would be inadmissible. In any case in which the
common trunk is thus short, it would probably be more prudent to place
a ligature on the external iliac and another on the internal iliac, at the
origin of each, than to tie the common iliac artery, or the external iliac
alone near its commencement.
The surgeon has it in his power to judge of the length of the artery during
1014 SURGICAL ANATOMY OF THE ARTERIES.
the operation, and to determine as to the propriety of tying the one vessel or
the other, for the iliac arteries are under his view almost as fully as if
dissected. Arteries in other parts of the body are, on the contrary, only
seen at the point at which it has been beforehand determined to place the
ligature.
SURGICAL ANATOMY OF THE INTERNAL ILIAC ARTERY.
This artery has been tied for aneurism affecting one of its large branches
on the back of the pelvis — the gluteal or sciatic (p. 420). It is arrived at
by dividing the abdominal muscles before the iliac fossa to a greater extent
than is required for exposing the external iliac — in the manner of the
operation first mentioned for the common iliac artery. The vein, a large
one, is, it will be borne in mind, behind the artery and in contact with it
[plate 55]; it is occasionally double [plate 58, fig. 6].
There is some difference in the degree of difficulty that would be ex-
perienced in securing the internal iliac artery in different cases. This is
owing to the fact that, when short, (and, as stated before, it often is so,)
ths artery is placed deeply in the pelvis ; whereas, when the leugth is more
considerable, it is accessible above that cavity.
Again, when the artery is very short, [as represented, for instance, in
plate 58, fig. l], it would probably be more safe to tie the common iliac, or
both the external and the internal iliacs at their origin, than to place a ligature
on the latter only, close to a strong current of blood.
SURGICAL ANATOMY OF THE EXTERNAL ILIAC ARTERY.
The external iliac artery (p. 431) admits of being tied in a surgical opera-
tion at any part except near its upper and lower end ; the near neighbour-
hood of the upper end being excepted on account of the circulation through
the internal iliac, and the lower end on account of the common position of the
branches (epigastric and circumflex iliac). Occasional deductions from this
statement occur in consequence of a branch or branches taking origin near or
at the middle of the artery ; and, as the operator may see such a branch, he
will avoid placing a ligature very near it.
The incision through the muscles to reach the artery, commencing a
little above the middle of Poupart's ligament, may be directed parallel with
the ligament upwards and outwards as far as its outer end, where the
incision may be curved with advantage for a short space (about an inch) up-
wards.
This and the other iliac arteries might be operated on by means of straight
incisions in a line from the umbilicus to the middle of Poupart's ligament,
or a little to the outer side of this line. But the division of the muscles on
the fore part of the abdomen is liable to the objection that the peritoneum
must be disturbed in front as well as behind ; and, moreover, a curved inci-
sion has the advantage of giving more room laterally than one which is merely
straight.
The muscles and the fascia transversalis being divided, and the peri-
toneum (to which the spermatic vessels adhere) being raised, the artery is
found where the finger of the surgeon, introduced into the wound,
begins to descend into the true pelvis, along the border of the psoas
muscle.
In contact with the artery will be seen the following structures, each
occupying the position already mentioned, viz., lymphatic glands, the cir-
cumflex iliac vein, and the external iliac vein [plate 55].
FEMORAL ARTERY. 1015
In order to pass the ligature, it is necessary to divide the thin and some-
times resistent subserous membrane, which binds the vessel down to the
fascia iliuca.
SURGICAL ANATOMY OF THE FEMORAL ARTERY.
The femoral artery (p. 434) is accessible to the surgeon for the application
of a ligature without serious difficulty in its en tire length ; but, as the lower
half is deeply placed, the difficulty of reaching this part is greatest, and
renders it necessary to divide and disturb the surrounding structures to a
greater extent than where the vessel is nearer the surface. For these
reasons the upper part of the artery is to be preferred for the performance
of the operation adverted to, in all cases in which other circumstances do
not control the choice of the surgeon. But the upper part of the femoral
artery is not equally eligible for the application of a ligature at all points,
in consequence of the position of the branches — an important consideration
in the surgical anatomy of this vessel.
Close to the commencement of this artery are two considerable branches
(epigastric and circumflex iliac) ; and between one and two inches lower
down the deep femoral branch ordinarily takes its rise. A ligature placed
on the arterial trunk in the interval between those branches, that is to say,
on the common femoral artery, is in the near neighbourhood of two dis-
turbing causes, — two sources of danger, so near that the prospect of a favour-
able issue to the operation is, under ordinary circumstances, very small.
Moreover, it has been shown amid the facts detailed before (p. 441), that
the origin of the deep femoral is often less than the average distance from
Poupart's ligament ; and that, not unfrequently, a considerable branch (one
of the circumflex arteries) takes its rise from the common femoral artery.
When these circumstances are considered, the operation of tying the
common femoral artery, or the femoral artery within two inches of ita
commencement, must be regarded as very unsafe. And it may be added,
that the conclusion to which the anatomical facts would lead is fully
confirmed by the results of cases in which the operation has been actually
performed.
It remains to determine where a ligature applied to the main artery
shall be sufficiently distant from the origin of the deep femoral below it, to
be free from the disturbing influence of the circulation through that great
branch. It has been shown that now and then a case occurs in which the
profunda is given off at the distance of from two to three inches below Pou-
part's ligament — in only a single instance out of a large number of observa-
tions did the space referred to amount to four inches.
From the foregoing remarks the inference to be deduced is, that the- part
of the femoral artery to be preferred for the operation supposed, is at the
distance of between four and five inches below the lower margin of the
abdominal muscles.
Remarks on the ojjeration. — The position of the artery being determined,
and the integument and fat divided, a vein may be met with lying on the
fascia, over the course of the artery. Ihe saphenous vein, being nearer to
the inner side of the limb than the line of incision, is not seen in the opera-
tion. The fascia lata, which is now to be divided, has a more opaque ap-
pearance over the vessels than over the muscles, for the colour of the latter
appears through the membrane. After dividing the fascia, the edge of the
sartorius muscle will, in many cases, require to be turned aside ; and occar
1016
SURGICAL ANATOMY OF THE ARTERIES.
sionally this muscle crosses the thigh so directly, that it must be drawn con-
siderably outwards in order to reach the artery [plate 74, fig. 4]. To the
exact point at which the sheath of the vessels, and even the fascia should be
Fig. 702. Fig. 702. — SUPERFICIAL DISSECTION OP THE
FEMORAL VESSELS, WITH THEIR SMALLER
BRANCHES IN THE RiaHT GROIN (from
R. Quain). i
a, the integument of the abdomen ; 6, the
superficial abdominal fascia ; &', the part
descending on the spermatic cord ; c, c, the
aponeurosis of the external oblique muscle ;
c', the same near the external abdominal
ring ; c", the inner pillar of the ring ; d, the
iliac part of the fascia lata ; d\ the pubic
part, e, e, the sheath, of the femoral vessels
laid open, the upper letter is immediately
over the crural aperture; e', placed on the
sartorius muscle partially exposed, points to
the margin of the saphenic opening ; 1,
femoral artery, having the femoral vein 2,
to its inner side, and the septum of the
sheath shown between the two vessels ; 3, the
principal saphenous vein ; 3', its anterior
branch ; 4, the superficial circumflex iliac
vein and arterial branches to the glands of
the groin ; 5, the superficial epigastric vein ;
6, the external pudic arteries and veins ; 7
to 8, some of the lower inguinal glands re-
ceiving twigs from the vessels ; 9, internal,
10, middle, and 11, external cutaneous
nerves.
cut through, the pulsation of the artery
will guide the operator. A small
nerve may present itself in this part of the operation. The immediate invest-
ment of the artery should be opened to the smallest possible extent, and the
knife or other instrument should be sparingly used at this stage of the ope-
ration : the object being to disturb the artery from its connections, including
its nutrient vessels (vasa vasorum), as little as possible, and likewise to avoid
wounding any of the small muscular branches which spring from most
arteries at irregular intervals. The division of an artery of the size of those
last referred to at a distance from the source from which it springs is of
little importance. It contracts, and soon ceases to bleed. But when it is
divided close to the trunk, blood issues from it as it would if an opening
equal in size to the calibre of the little branch were made in the trunk
itself.
In order to avoid injuring the vein, which is separated from the artery
only by a thin partition of areolar tissue, the point of the aneurism-needle,
which conveys the ligature, is to be kept close to the artery.
Other veins of occasional occurrence may render increased care necessary,
for example, those small branches which cross the artery or course along
its surface ; or it may be a larger vein — a division of the femoral vein when
it is double, or the deep femoral vein when the ligature is applied a little
higher than usual [plate 75].
To reach the femoral artery in the middle of the thigh, the depth of the
vessel being considerable, the incision through the integuments must be pro-
portionally long. As the sartorius is directly over the vessel, the opera-
FEMOKAL ARTERY. LIGATURE.
1017
tion may be performed by turning the muscle either towards the outer or
the inner side of the limb ; and the incision would be made according to
the plan adopted, at the inner or the outer margin of the muscle. The
Fig. 703.
Fig. 703.— DEEP VIEW OP THE FEMO-
RAL ARTERY AND ITS BRANCHES ON
THE LEFT SIDE (from R. Quain). 5
The sartorius muscle has been re-
moved in part, so as to expose _ the
artery in the middle third of the thigh ;
a, the anterior superior iliac spine ; b,
the aponeurosis of the external oblique
muscle near the outer abdominal ring,
from which the spermatic cord is seen
descending towards the scrotum ; c,
the upper part of the rectus femoris
muscle ; d, abductor longus ; et fibrous
sheath of Hunter's canal covering the
artery ; 1, femoral artery ; 1', femoral
vein divided and tied close below Pou-
part's ligament ; 2, profunda femoris
artery ; 3, anterior crural nerves ; 4>
internal circumflex branch; 5, super-
ficial pudic branches ; 6, external cir-
cumflex branch, with its ascending
transverse and descending branches
separating from it ; 6', twigs to the
rectus muscle ; 7, branches to the
vastus internus muscle ; 8, and 9,
some of the muscular branches of the
femoral.
preferable mode appears to be
to divide the integument on or
over the muscle, near its inner
margin, so as to arrive directly
upon the muscle and draw it
outwards, after cutting freely
through the investing fascia.
The fibrous structure stretched
over the vessels from the adduc-
tors to the vastus internus muscle
being divided, the position of the
femoral vein and saphenous nerve
are to be kept in view in com-
pleting the operation. In the
first steps of the operation in this
part of the thigh, injury to the
long saphenous vein is to be guarded against.
Before concluding the observations on the femoral artery, a very small
class of cases claims a word of notice. It has happened (in Sir Charles Bell's
case) that the application of a ligature to a femoral artery has not been fol-
lowed by the usual consequence of cessation of the pulsation in the aneurism ;
and the uninterrupted continuance of the circulation was found, on exami-
nation after death, to be attributable to the circumstance of the artery being
double where the ligature was applied, while the two parts became re-united
above the tumour. If such a case should again be met with in an opera-
1018 SURGICAL ANATOMY OF HERNIJE.
tion, the surgeon instructed by the case alluded to, and by other examples
of the same arrangement of the arteries which have since been observed,
might at once, under the guidance of the pulsation, or of the effect of
pressure in controlling the circulation through the aneurism, divide the
covering of areolar tissue over the second part of the artery, and tie it
likewise.
II. SURGICAL ANATOMY OF THE PARTS CONCERNED IN
CERTAIN ABDOMINAL HERNIA.
Besides the surgical anatomy of the principal arteries, certain parts of
the walls of the abomen and pelvis are to be now considered with refer-
ence to surgical operations in which the viscera of those cavities are from
time to time concerned.
The walls of the abdomen, when in a healthy state, unaffected by injury,
disease, or malformation, retain the viscera within the cavity under all
circumstances ; but where certain natural openings exist for the passage of
blood-vessels, protrusions of the viscera, constituting the disease named
" hernia" or " rupture " are liable to occur under the influence of the com-
pression to which the organs are subjected during the production of efforts.
For the replacement of the viscus so protruded, an accurate acquaintance
with the structure of the part through which the protrusion takes place is
required by the surgeon ; and, on this account, an examination of the seat
of the hernia as a surgical region becomes necessary.
Two of the openings by which hernise escape from the abdomen are
situate close together at the groin. One is the canal in the lower part of
the broad abdominal muscles, which gives passage in the male to the duct
and vessels of the testis (spermatic cord), and in the female to the round
ligament of the womb. The second opening exists at the inner side of the
large femoral blood-vessels.
Hernial protrusions are likewise found to escape at the umbilicus, in
the course of the blood-vessels which occupy that opening in the foetus, or
in the immediate neighbourhood of the opening ; and at the thyroid foramen,
where the obturator vessels and nerve pass downwards to the adductor
muscles of the thigh. According to the situation they occupy these hernke
are named respectively inguinal, femoral, umbilical, and obturator. They
will now be separately noticed ; but, inasmuch as the structure of the parts
connected with the umbilical and obturator hernias is by no means intricate,
and as, moreover, it is noticed with sufficient detail in text-books of prac-
tical surgery, it will be unnecessary to refer farther in this work to those
forms of hernia.
OF THE PARTS CONCERNED IN INGUINAL HERNIA.
The inguinal hernia, it has been stated above, follows the course of the
spermatic cord from the cavity of the abdomen. We shall therefore, before
adverting to the hernia! protrusions, examine the structure of the abdominal
walls in the neighbourhood of the canal in which the cord is placed ; and
for this purpose it will be supposed that the constituents of those walls are
successively laid bare and everted to such an extent as would be permitted
by two incisions made through them, and reaching, one along the linea
alba for the length of three or four inches from the pubes, the other, from
the upper end of the vertical incision outwards to the superior spine of the
hip-bone.
The superficial fascia (p. 257) is connected along the fold of the groin
INGUINAL HEENIA. ANATOMY OF THE GROIN. 1019
with Poupart's ligament and the upper end of the fascia lata ; and, after
descending over the spermatic cord into the scrotum, it becomes continuous
with the membrane of the same kind which covers the perinseum. Its
thickness varies much in different persons, on account of the different quan-
tity of fat contained within its meshes ; but in the scrotum the fascia is
devoid of fat ; as it also is elsewhere towards the internal surface, where
its density is at the same time augmented. From the varying thickness of
this structure on the abdomen and the scrotum, as well as in different
persons, it will be inferred that the depth of incision required to divide it
in an operation must vary considerably.
The superficial vessels of the groin are encased by the fascia, and are held
to separate it into two layers. The vessels which ramify over the inguinal
canal and the scrotum are the external pudic and epigastric arteries and
veins (p. 437 and 475). The veins, especially the epigastric, are consider-
ably larger than the arteries they accompany. Some of these vessels are
wounded in operations performed for the relief of strangulated hernia ; but
the bleeding from them is small in quantity and rarely requires the applica-
tion of a ligature or other means to arrest it. The lymphatic glands of the
groin (p. 489) admit of being arranged in two sets — one being placed over
Poupart's ligament and parallel with that structure ; while the other series
is upon the upper part of the thigh at its middle, about the saphenous
opening in the fascia lata.
When the superficial fascia is removed, the aponeurosis of the external
oblique muscle (p. 249) is in view, together with, in the male body, the
spermatic cord, in the female body the round ligament of the uterus, which
emerge from an opening close to the outer side of the pubic spine. The
lowest fibres of the aponeurosis, as they approach the pubes, become sepa-
rated into two bundles which leave an interval between them for the passage
of the cord or round ligament. One of the bands, the upper one and the
smaller of the two, is fixed in front of the symphysis of the pubes ; and the
lower band, which forms the lower margin of the apoueurosis, being stretched
between the anterior superior iliac spine and the pubes, is named Poupart's
ligament, or the femoral arch. This latter tendinous band has considerable
breadth. It is fixed at the inner end to the spine of the pubes, and, for
some space outside that process of the bone, to the pectin eal ridge. In
conseqiience of the position of the pectiueal ridge at the back part of the
bone, the ligament is tucked backwards ; and its upper surface affords space
for the attachment of the other broad muscles, at the same time that it
supports the spermatic cord. Poupart's ligament does not He in a straight
line between its two fixed points ; it curves downwards, and with the curved
border the fascia lata is connected. It is owing to the last-mentioned fact
that the so-named ligament, together with the rest of the aponeurosis of the
external oblique, is influenced by the position of the thigh, being relaxed
when the limb is bent, and the converse. Moreover, the change of the
position of the limb exercises a corresponding influence on the state of the
other structures connected with Poupart's ligament.
The interval left by the separation of the fibres of the aponeurosis above
referred to, is named the external abdominal ring) and the two bands by
which it is bounded are known as its pillars or columns. The space is
triangular in shape, its base being the crest of the pubes, while the apex is
at the point of separation of the two columns. The size of the ring varies
considerably in different bodies ; — in one case its sides will be found closely
applied to the spermatic cord ; while, in another, on the contrary, the space
1020
SURGICAL ANATOMY OF HERNIA.
is so considerable as to be an obvious source of weakness to the abdominal
parietes. It is usually smaller in the female than in the male body.
Fig. 704.
Fig. 704. — THE APONEUROSIS OP THE
EXTERNAL OBLIQUE MUSCLE AND
THE FASCIA LATA.
1, the internal pillar of the ab-
dominal ring ; 2, the external pillar
of the same (Poupart's ligament) ; 3,
transverse fibres of the aponeurosis ;
4, pubic part of tbe fascia lata ; 5, the
spermatic cord ; 6, the long saphenous
vein \ 7, fascia lata.
Between the pillars of the
abdominal ring is stretched a
thin fascia, named from that
circumstance, " intercolumnar ; "
and a thin diaphanous mem-
brane prolonged from the edges
of the opening affords a covering
(fascia sperm atica) to the sper-
matic cord and the tunica vagi-
nalis testis. The cord, in passing
through the ring, lies over the
outer pillar.
Fig. 705.
Fig. 705. — DEEPER DISSECTION OP THE ABDOMINAL WALL IN THE GROIN.
The aponeurosis of the external oblique muscle having been divided and turned down,
the internal oblique is brought into view with the spermatic cord escaping beneath its
lower edge; 1, apoueurosis of the external oblique; 1', lower part of the same turned
down ; 2, internal oblique muscle ; 3, spermatic cord ; 4, saphenous vein.
ANATOMY OF THE GROIX.
1021
Internal oblique muscle (p. 250) — After removing the aponeurosis of the
external oblique, this muscle is laid bare. The lower fibres are thin and
often of a pale colour. Immediately above Poupart's ligament the outer
part is muscular, the inner part tendinous. The spermatic cord, when about
to escape at the external abdominal ring, passes beneath the fleshy part of
the muscle. The fibres in this situation varying considerably in direction
from those of the rest of the muscle, pass inwards from Poupart's ligament
at first nearly parallel with that structure ; and, becoming tendinous, they
join with the tendon of the transversalis.
Fig. 706.
Fig. 706. — THE INGUINAL CANAL AND FEMORAL SHEATH FULLY EXPOSED.
After the removal of the lower part of the external oblique (with the exception of a
small slip including Poupart's ligament), the lower portion of the internal oblique has been
raised, and thereby the transversalis muscle and fascia have been brought into view. The
femoral artery and vein are seen to a small extent, the fascia lata having been turned
aside and the sheath of the blood-vessels laid open. 1, external oblique muscle; 2,
internal oblique ; 2', part of same turned up; 3, transversalis muscle. Upon the last-
named muscle is seen a branch of the circumflex iliac artery, with its companion veins;
and some ascending tendinous fibres are seen over the conjoined tendon of the two last-
named muscles ; 4, transversalis fascia ; 5, spermatic cord covered with the infundibuli-
form fascia from the preceding. 6, upper angle of the iliac part of fascia lata ; 7, the sheath
of the femoral vessels ; 8, femoral artery; 9, femoral vein; 10, saphenous vein; 11, a
vein joining it.
Transversalis muscle. — This muscle (p. 253) does not, in general extend
down as far as the internal oblique ; so that, the latter being removed, an
interval is observable between the edge of the transversalis and Poupart's
ligament, in which the transversalis fascia comes into view ; and in which
the spermatic cord is seen after having penetrated that fascia. The lower
edge of the muscle is commonly close above the opening for the cord in the
subjacent membrane, while its tendon curves to the inner side ; so that
1022 SURGICAL ANATOMY OF HERNI^E.
the margin of the muscle with its tendon has a semicircular direction with
respect to the aperture.
The tendinous fibres in which the fleshy parts of the two preceding
muscles end, are connected together so as to form one layer, which is named
the "conjoined tendon of the internal oblique and transverse muscles."
This tendon is fixed to the crest of the pubes in front of the rectus muscle,
and likewise to the pectineal ridge. It is thus behind the external abdo-
minal ring, and serves to strengthen the wall of the abdomen where it is
weakened by the presence of that opening.
A band of tendinous fibres, directed upwards and inwards over the
conjoined tendon in a triangular form, gives additional strength to the
abdominal wall in the same situation, but the fibres of this structure are
often very indistinct.
Where the spermatic cord is in apposition with the preceding muscle,
the cremaster muscle of the testis descends over it. The fibres which com-
pose this muscle are, from their colour, more easily distinguished than the
other investments of the cord ; and this is especially the case in robust
persons ; or when they are hypertrophied, as sometimes happens in cases
of long-standing hernia. The outer part of the cremaster is much larger
than the portion connected with the pubes ; and the latter is sometimes
absent (p. 253).
When observed in different bodies the lower parts of the internal oblique and
transverse muscles present some differences in their physical characters as well as
in the manner in which they are disposed with respect to the spermatic cord.
Thus :—
a. The transversalis, in some cases, is attached to but a small part of Poupart's
ligament, and leaves, therefore, a larger part of the abdominal wall without its sup-
port. On the other hand, that muscle may be found to extend so low clown as to
cover the internal abdominal ring together with the spermatic cord, for a short space.
Not unfrequently the fleshy fibres of the two muscles are blended together as well as
their tendons.
6. Cases occasionally occur in which the spermatic cord, instead of escaping beneath
the margin of the internal oblique, is found to pass through the muscle, so that
some muscular fibres are below as well as above it. And examples of the transversalis
being penetrated by that structure in the same manner are recorded.*
c. In his latest account of the structure of these parts Sir A. Cooper described the lower
edge of the transversalis as curved all round the internal ring and the spermatic cord.
" But the lower edge of the transversalis has a very peculiar insertion, which I have
hinted at in my work on Hernia. It begins to be fixed in Poupart's ligament, almost
immediately below the commencement of the internal ring, and it continues to be in-
serted behind the spermatic cord into Poupart's ligament as far as the attachment of
the rectus."f With this disposition of its fibres, the muscles would, in the opinion of
the last-cited authority, have the effect of a sphincter, in closing the internal ring,
and would thus tend to prevent the occurrence of hernia. But the principal object
with which the attention of surgeons has been fixed on the muscles in this situation,
is in order to account for the active strangulation of hernial protrusions at the internal
abdominal ring, and in the inguinal canal.
Fascia transversalis. — This membrane is described as part of the general
lining of the abdominal walls (p. 258). Closely connected with the trans-
versalis muscle by means of the areolar tissue interposed between the fleshy
fibres of the muscle, it is united below to the posterior edge of Poupart's
* Eecherches Anatomiques sur les Hermes, &c., par J. Cloquet, p. 18 and 23. Pans,
1817. Inguinal and Femoral Heruiae, by G. J. Guthrie, plate I. London, 1833.
•f* Observations on the Structure and Diseases of the Testis, second edition, p. 36. Ed.
by Bransby B. Cooper, F.R.S. London, 1841.
THE INGUINAL CANAL. 1023
ligament, there joining with the fascia iliaca ; and on the inner side it blends
•with the conjoined tendon of the internal oblique and transversalis muscles,
as well as with the tendon of the rectus. The fascia possesses very different
degrees of density in different cases ; in some being little more than a loose
areolar texture, while in others it is so resistant at the groin — towards which
part it increases in thickness, and especially at the lower side of the
internal abdominal ring — that it is calculated to afford material assistance
to the muscles in supporting the viscera. By an oval opening in this mem-
brane the spermatic cord, or the round ligament of the womb, begins its
course through the abdominal parietes. This opening, named the internal
abdominal ring, is opposite the middle of Poupart's ligament, and usually
close above that structure, but occasionally at a distance of three or four
lines from it. Its size varies a good deal in different persons, and is consi-
derably greater in the male than the female. From the edge of the ring
a thin funnel-shaped elongation (iufundibuliform fascia ; fascia spermatica
iuterna, Cooper), is continued over the vessels of the spermatic cord.
Epigastric Artery. — The position of this vessel is one of the most im-
portant points in the anatomy of the inguinal region, from the close
connection which it has with the different forms of inguinal hernia and with
the femoral hernia. Accompanied by two veins (in some instances by only
one) the vessel ascends under cover of the fascia last described obliquely to
the rectus muscle, behind which it then proceeds to its ultimate distribu-
tion (p. 432). In this course the artery runs along the inner side of the
internal abdominal ring — close to the edge of the aperture or at a short
interval from it. The vessels of the spermatic cord are therefore near to
the epigastric artery ; and the vas deferens, in turning from the ring into
the pelvis, may be said to hook round it.
The Inguinal Canal. — This channel, by which the spermatic cord passes
through the abdominal muscles to the testis, begins at the internal abdo-
minal ring, and ends at the external one. It is oblique in its direction,
being parallel with and immediately above the inner half of Poupart's liga-
ment ; and it measures two inches in length. In front the canal is bounded
by the aponeurosis of the external oblique muscle in its whole length, and
at the outer end by the fleshy part of the internal oblique also ; behind it,
is the fascia transversalis, together with, towards the inner end, the con-
joined tendon of the two deeper abdominal muscles. Below, the canal is
supported by the broad surface of Poupart's ligament, which separates it
from the sheath on the large blood-vessels descending to the thigh, and from
the femoral canal at the inner side of those vessels.
The spermatic cord, which occupies the inguinal canal, is composed of
the arteries, veins, lymphatics, nerves, and excretory duct (vas deferens) of
the testis, together with a quantity of loose areolar tissue mixed up with
those parts. The direction of the vessels just enumerated requires notice.
The artery and vein incline outwards from the lumbar part of the vertebral
column to roach the internal abdominal ring, where, after being joined by
the vas deferens as it emerges from the pelvis they change their course,
inclining inwards along the inguinal canal ; at the end of which they
become vertical. There are thus repeated alterations in the direction of
the vessels ; and while at the beginning and ending all are close to the
middle line of the body, they are considerably removed from that point
where they come together to emerge from the abdominal cavity.
The coverings given from the constituent parts of the abdominal wall to
the spermatic cord and the testis, namely, the creiaasteric muscular fibres
1024 SUBGICAL ANATOMY OF HERNLZE.
with the two layers of fascia (the infundibuliform aud spermatic fascisa)
between which those fibres are placed, are very thin in their natural state ;
but they may be readily distinguished in a surgical operation from the
investing superficial fascia, by their comparative density and the absence
of fat.
In order to examine the peritoneum at the groin, it will be best to
divide that membrane with the abdominal muscles by two incisions drawn
from the umbilicus — one to the hip-bone, the other to the pubes. The flap
thus formed being held somewhat outwards, and kept tense, a favourable
view will be obtained of the two fossae (inguinal fossw or pouches) with the
intervening crescentic fold. This fold is formed by the cord remaining
from the obliterated umbilical artery, which being shorter than the outer
surface of the serous sac, causes this to project inwards ; and as the length
of the cord differs in different cases, so likewise do the size and prominence
of the peritoneal fold vary accordingly.
The lowest part of the outer fossa will be generally found opposite to
the entrance into the internal abdominal ring and the femoral ring, while
the inner one corresponds with the situation of the external abdominal
ring. But the cord representing the umbilical artery, which it has been
stated causes the projection of the serous membrane into a fold, does not
uniformly occupy the same position in all cases. Most frequently it is
separated by an interval from the epigastric artery, while in some cases it
is immediately behind that vessel. There is necessarily a corresponding
variation in the extent of the external peritoneal fossa. This fact will
find its practical application when the internal form of inguinal hernia is
under consideration.
Between the peritoneum and the fascia lining the abdominal muscles is
a connecting layer of areolar structure named the subserous areolar mem-
brane. A considerable quantity of fat is in some cases found in this
membrane.
The relative position of some of the parts above referred to may be
here conveniently stated, by means of measurements, made by Sir A.
Cooper, and adopted after examination by J. Cloquet. But, as the distance
between given parts varies in different cases, the following measurements
must be regarded only as a general average : —
MALE. FEMALE.
From the symphysis of the pubes to the anterior ) K1 . ,
superior spine of the ilium . . .[^inches. ... 6 inches.
From the same point to the spine of the pubes . . 1| ,, ... If ,,
,, to the inner part of the external ) ni 1
abdominal ring \ Ug " '" "
,, to the inner edge of the internal [ „ 01
abdominal ring \ 6 " ••• 6* »»
,, to the epigastric artery on the inner ) ^a 01
side of the internal abdominal ring . .\ * " '" s "
From the preceding account of the structure of the abdominal wall at
the groin, it will be inferred that the defence against the protrusion of the
viscera from the cavity is here weaker than at other parts. The external
oblique muscle and the fascia transversalis are perforated, while the two
intervening muscles are thinner than elsewhere, and more or less defec-
tive. To this it must be added that the viscera are impelled towards
the same part of the abdomen by the contraction of the diaphragm and
the other abdominal muscles, in the production of efforts to overcome
OBLIQUE INGUINAL HERNIA. 1025
resistance ; and these are the circumstances under which protrusions actually
take place.
INGUINAL HERNIA.
The protrusions of the viscera, or hernise, which occur in the course of
the inguinal canal, are named " inguinal" Of this form of the disease
two varieties are recognised : and they are distinguished according to the
part of the canal which they first enter, as well as by the position which they
bear with respect to the epigastric artery. Thus, when the hernia takes
the course of the inguinal canal from its commencement, it is named
oblique, because of the direction of the canal, or external, from the position
which its neck bears with respect to the epigastric artery. On the other
hand, when the protruded part, without following the length of the canal, is
forced at once through its termination, i. e. through the external abdominal
ring, the hernia is named, from its course, direct, or, from its relation to
the epigastric artery, internal. In these, the two principal varieties of
inguinal hernia, there are some modifications which will be adverted to in
the special notice of each.
Oblique inguinal hernia. — In the common form of this hernia the pro-
truded viscus carries before it a covering of peritoneum (the sac of the hernia),
derived from the outer fossa of that serous membrane ; and, in passing along
the inguinal canal to the scrotum, it is successively clothed with the cover-
ings given to the spermatic vessels from the abdominal parietes. The hernia
and its pac lie directly in front of the vessels of the spermatic cord (the intes-
tines and the peritoneum having the same position relatively to those vessels
in the abdomen) ; but, when the disease is of long standing, the vessels may
be found to be separated from each other,, and pressed more or less towards
the side or even the fore part of the sac, under the influence of the weight
of the tumour. The hernia does not extend below the testis, even when it
attains large size. That it does not is owing, doubtless, to the intimate
connection which the coverings of the cord have with the tunica vaginalis
testis.
When the hernia does not extend beyond the inguinal canal, it is distin-
guished by the name bubonocele: and when it reaches the scrotum, it is com-
monly named from that circumstance scrotal hernia.
There are two other varieties of oblique inguinal hernia, in which the
peculiarity depends on the condition of the process of peritoneum that accom-
panies the testis \vhen this organ is moved from the abdomen. In ordinary
circumstances the part of the peritoneum, connected immediately with the
testis, becomes separated from the general cavity of that serous membrane
by the obliteration of the intervening canal ; and the hernial protrusion
occurring after such obliteration has been completed, carries with it a dis-
tinct serous investment — the sac. But if the hernia should be formed before
the process of obliteration is begun, the protruded part is then received into
the cavity of the tunica vagiualis testis, which serves in the place of its
sac. In this case the hernia is named congenital (hernia tunicse vaginalis, —
Cooper). It is thus designated, because the condition necessary for its for-
mation usually exists only about the time of birth ; but the same variety of
the complaint is occasionally found to be first formed in the adult, obviously
in consequence of the tunica vagiualis remaining unclosed, — still continuous
with the peritoneum. The congenital hernia, should it reach the scrotum,
passes below the testis ; and, this organ being imbedded in the protrude^
3 x
1026
SURGICAL ANATOMY OF HERNO2.
viscus, a careful examination is necessary in order to detect its position.
This peculiarity serves to distinguish the congenital from the ordinary form
of the disease.
Fig. 707.
B.
Fig. 707. — DIAGRAMS OP A PART OF THE
PERITONEUM AND THE TUNICA VAQINA-
LIS TESTIS.
In the first, A, the serous investment of
the testis is seen to be an elongation from
the peritoneum ; while in the second, B,
the two membi-anes are shown distinct from
each other. 1, the peritoneal cavity ; 2,
the testis.
To the second variety of inguinal
hernia, in which the distinguishing
character depends on the state of the
tunica vaginalis testis, the name " in-
fantile " has been applied (Hey). The hernia in this case is covered with a
distinct sac, the peculiarity consisting in the circumstance of the rupture
with its sac being invested by the upper end of the tunica vaginalis. The
relative position of the two serous membranes (the hernial sac and the tunica
vaginalis) may be accounted for by supposing the hernia to descend when the
process of the peritoneum, which accompanies the testis from the abdomen,
has been merely closed at the upper end, but not obliterated for any length.
As the tunica vaginalis at this period extends upwards to the wall of the
abdomen, the hernia, in its descent, soon meets that membrane and becomes
invested by it. The exact mode of the investment has not yet been clearly
made out by dissection. It may be that the hernia passes behind the upper
end of the large serous tunic of the testis, which then laps round the sac
from before, or that the tunica vaginalis is inverted from above so as to
receive the hernia in a depression. But the fact most material for the sur-
geon is fully ascertained — namely, that during an operation in such a case,
the hernial sac is met with only after another serous bag (the tunica vagi-
nalis testis) has been divided. The peculiarity here described has been
repeatedly found present in the recently formed hernia of grown persons.
The term infantile, therefore, like congenital, has reference to the condition
of certain parts, rather than to the period of life at which the disease is first
formed.
In the female, oblique inguinal hernia follows the course of the round
ligament of the uterus along the inguinal canal, in the same manner as in
the male it follows the spermatic cord. After escaping from the external
abdominal ring, the hernia lodges in the labium pudendi. The coverings are
the same as those in the male body, with the exception of the cremaster,
which does not exist in the female : but it occasionally happens that some
fibres of the internal oblique muscle are drawn down over this hernia in
loops, so as to have the appearance of a cremaster (Cloquet).
A strictly congenital inguinal hernia may occur in the female, the pro-
truded parts being received into the little diverticulum of the peritoneum
(canal of Nuck), which sometimes extends into the inguinal canal with the
round ligament. But as this process of the peritoneum, in such circum-
stances, would probably not differ in any respect from the ordinary sac,
there are no means of distinguishing a congenital hernia in the female
body.
DIRECT IXGUIXAL IIEKNTA.
1027
Direct inguinal hernia (internal : ventro-iuguinal). — Instead of following
the whole course of the inguinal canal, in the manner of the hernia above
described, the viscus in this case is protruded from the abdomen to the
groin directly through the lower end of the canal, at the external abdominal
ring ; and at this point the two forms of hernia, if they co-existed, would
come together. At the part of the abdominal wall through which the direct
inguinal hernia finds its way, there is recognised on its posterior aspect a
triangular interval, the sides of which are formed by the epigastric artery,
and the margin of the rectus muscle, and the base by Poupart's ligament.
It is commonly named the triangle of Hesselbach. Through this space the
hernia is protruded, carrying before it a sac from the internal fossa of the
peritoneum ; and it is in general forced onwards directly into the external
abdominal ring.
Fig. 708. — INTERNAL VIEW OF THE
VESSELS RELATED TO THE GROIN.
A portion of the wall of the abdo-
men and the pelvis is here seen on the
posterior aspect, the os innominatum
of the left side and the soft parts con-
nected with it having been removed
from the rest of the body. 1, symphysis
of the pubes ; 2, irregular surface of
the hip-bone which has been separated
from the sacrum ; 3, ischial spine ; 4,
ischial tuberosity ; 5, obturator inter-
nus ; 6, rectus, covered with an elonga-
tion from 7, fascia transversalis ; 8,
fascia iliaca covering the iliacus muscle ;
9, psoas magnus cut ; 10, iliac artery ;
11, iliac vein ; 12, epigastric artery and
its two accompanying veins ; 1 3, vessels
of the spermatic cord, entering the abdo-
minal wall at the internal ring. The
ring was in this case of small size ; 14,
two obturator veins ; 15, the obi iterated
umbilical artery. The cord, it will be
remembered, is not naturally in contact
with the abdominal parietes in this
situation.
The coverings of this hernia, taking them in the crder in which they are
successively applied to the protruded viscus, are the following :— The peri-
toneal sac ahd the subserous membrane which adheres to it, the fascia
transversalis, the tendon common to the internal oblique and transverse
muscles, and the intercolumnar (external spermatic) fascia derived from the
margin of the external abdominal ring, together with the superficial fascia
and the integuments.
With respect to one of the structures enumerated, namely, the common
tendon of the two deeper muscles, considerable variety exists as to its
disposition in different cases. In place of being covered by that tendon,
the hernia may be found to pass through an opening in its fibres, or to
escape beneath it. Cremasteric muscular fibres are met with (rarely, how-
ever,) upon this hernia.
The spermatic cord is commonly placed behind the outer part of the
direct inguinal hernia, especially at the external abdominal ring. It is
here that the hernia and the cord in most cases first come together ; and
3x2
1028
SURGICAL ANATOMY OF HERNIJE.
their relative position results from the poiuts at which they respectively
pass through the ring, the former being upon the crista of the pubes,
Fig. 709.
Fig. 709. — A DIRECT INGUINAL HER-
NIA ON THE LEFT SIDE, COVERED
BY TEE CONJOINED TENDON OF THE
INTERNAL OBLIQUE AND TRANS-
VERSE MUSCLES.
1, aponeurosis of the external ob-
lique ; 2, internal oblique turned up ;
3, transversal! s muscle ; 4, fascia
transversalis ; 5, spermatic cord ; 6,
the hernia. A small part of the epi-
gastric artery is seen through an
opening made .in the transversalis
fascia.
while the latter drops over the
outer pillar of the opening.
The hernial sac is not, how-
ever, in this case (as the sac
of the external form of the
disease is) in contact with the
vessels of the cord. The invest-
ments given from the fascia
transversalis to those vessels and to the hernia respectively, are inter-
posed.
But the point at which the internal inguinal hernia passes through the
Fig. 710.
Fig. 710.— A SMALL OBLIQDE INGUINAL
HERNIA, AND A DIRECT ONE ON THE
RIGHT SIDE.
A little of the epigastric artery has
been laid bare, by dividing the fascia
transversalis immediately over it. 1,
tendon of the external oblique; 2, in-
ternal oblique turned up ; 3, transver-
salis ; 4, its tendon (the epigastric artery
is shown below this number) ; 5, the
spermatic cord (its vessels separated) ;
6, a bubonocele ; 7, direct hernia pro-
truded beneath the conjoined tendon of
the two deeper muscles, and covered by
an elongation from the' fascia trans-
versalis.
triangular space above described,
as marked on the posterior aspect
of the abdominal wall, is subject
to some variation. Instead of
pushing directly through the ex-
ternal abdominal ring, (the most
frequent position), the hernia
occasionally enters the inguinal canal nearer to the epigastric artery, and,
passing through a portion of the canal to reach the external ring, has
therefore a certain degree of obliquity. This change in position may coin-
cide with a change of the peritoneal fossa, which furnishes the hernial sac
VARIETIES OF INGUINAL HERNIA. 1029
— a change, namely, from the internal fossa to the external one. The
alteration of the fossa does not, however, in all cases coincide with a change
in the position of the hernia ; for the cord remaining from the obliteration
of the umbilical artery, (which separates the fossae,) instead of crossing
behind the triangle of Hesselbach so as to leave room at each side of it
for a hernia to penetrate that space, lies, it has been already stated, some-
times directly behind the epigastric artery : — indeed, according to the
observations of Cloquet, it is most frequently in this position ;* and when
the cord in question is so placed, the hernia, whatever may be its position
in the triangle of Hesselbach, can occupy only the internal peritoneal fossa.
The inference, however, most important in a practical or surgical point of
view, to be drawn from the varying position of the neck of the internal
hernia, has reference not to the cord just alluded to, but to the epigastric
artery — i. e. to the greater or less distance of the neck of the sac from that
vessel.
The investments of the internal hernia are likewise liable to be influenced
by the position at which it penetrates the abdominal wall. It is in all
likelihood when the protrusion occurs outside the ordinary situation, that
the hernia escapes beneath the conjoined tendon of the two deeper muscles.
It is, moreover, under the same circumstances that the hernia is more
directly in front of the spermatic cord, and that the cremasteric fibres are
among its investments. (Ellis.)
The internal inguinal hernia is very rarely met with in the female. In
the single example of the disease observed by Richard Quaiu, as well as
in the cases (a very small number) found recorded iu books, the hernia,
though not inconsiderable in size, was still covered with the tendon of the
external oblique muscle, f
Distinctive diagnosis of oblique and direct inguinal hernice. — The following
circumstances, which are brought together from the facts detailed in the
preceding pages, or are inferences from those facts, will serve to distin-
guish the two forms of the disease from one another. The oblique hernia,
when recently formed, is elongated and narrow at its upper part, being
restrained by the tendon of the external oblique muscle. It is, however,
attended with a degree of fulness in the inguinal canal, as well as tender-
ness upon pressure being made over the canal. After passing through the
external abdominal ring, it is observed to be directly in front of the
spermatic cord. The direct hernia, when of small size, is globular ; it is
protruded more immediately over the pubes ; causes no fulness or tender-
ness in the canal ; and the spermatic cord is usually behind its outer side.
But the distinction between the two heruise admits of being made only
when the disease is recent and the tumour moderate in size ; for, when
oblique inguinal hernia is of long standing, and has attained considerable
* Recherches, &c., p. 39, note.
t See "Treatise on Ruptures," by Mr. Lawrence, 4th edit. p. 213, and an essay by
M. Velpeau in "Aunales de Chirurgie Franchise et etrangere," torn. i. p. 352.
M. Velpeau, in the essay just referred to, proposes to recognise three varieties of
internal hernia, viz., 1, the ordinary form which passes straight through the external
abdominal ring ; 2, an outer oblique variety, which passes through a part of the inguinal
canal ; and 3, an inner oblique one, which entering the abdominal wall close to the edge
of the rectus muscle, is directed outwards in order to reach the opening in the external
oblique muscle. The first two forms adverted to by M. Velpeau have been described in
the text. With respect to the third variety or class sought to be introduced by that
surgeon, it should be observed that he seems to have been led to propose it by the
observation of a single case— an example of internal hernia in the female.
1030 SURGICAL ANATOMY OF HERNIJE.
size, the obliquity of the inguinal canal no longer remains, — the internal
ring being enlarged and brought inwards opposite the external one, — while
at the same time the epigastric artery, borne inwards by the hernia, curves
along the inner side of the sac. Under this change, the oblique hernia
assumes the appearance of one primarily direct.
Operations for the relief of inguinal hernia. — This account of the dispo-
sition of the parts connected with the different forms of inguinal hernia
may be concluded by a brief statement of the application of the anatomical
facts in practical surgery, either in simply replacing the hernial protrusion,
or in the operation required to attain that object when the hernia is other-
wise irreducible. In the efforts to effect the replacement of the protruded
parts (the taxis), it is to be borne in mind that the abdominal muscles,
which, in most cases, are the sole obstacle to the attainment of that end,
become relaxed to some extent by flexing the thigh and inclining the trunk
forwards. The direction, too, which the protruded part follows through
the abdominal walls, ought to influence the direction given to the pressure
required in restoring it.
When the operation required to set free the constriction which prevents
the restoration of the protruded viscus to the abdomen is undertaken, the
parts covering the hernia or a portion of it at the upper end, are to be
divided, so as to allow the introduction of a knife beneath the " stricture";
and this (the stricture) will be found at the external ring, or, more fre-
quently, at the internal one. To accomplish the object, the tendon of the
external oblique is to be laid bare by an incision beginning somewhat above
the upper end of the hernia, and extending downwards below the external
ring. If, on examination, the stricture should be ascertained to be at the
last-named opening, the division of a few fibres of its circumference will
allow a sufficient dilatation for the replacement of the hernia ; but if, as
generally happens, the seat of the stricture should prove to be higher up, —
in the inguinal canal or at the internal ring, — the aponeurosis of the external
oblique is to be cut through over the canal, and the lower edge of the in-
ternal muscles, one of which commonly constitutes the stricture, is then to
be divided on a director insinuated beneath them.
In the operation indicated in the last paragraph, the sac of the hernia is
supposed to be left unopened, — the course which it is best to adopt when
the stricture is external to that membrane. Occasionally, however, it
happens that the sac itself is the cause of the constriction. When this is the
case, or when from some other reason the surgeon is unable, after such an
operation as that above noticed, to replace the hernia, it becomes necessary
to lay the sac open, in order to divide the constriction at its neck. When
the incision required in the last-mentioned step of the operation is being
made, the epigastric artery is not to be overlooked. From the position
which that vessel holds with respect to the oblique and direct forms of
hernia respectively, it necessarily follows that an incision outwards through
the neck of the sac, in the former variety of the disease, and inwards in the
latter, would be free from ri«k on account of the artery ; but, inasmuch as
the oblique hernia is liable, in time, to assume the appearance of one pri-
marily direct, and a want of certainty as to the diagnosis must, on this
account, exist in certain cases, — as, moreover, it is advantageous to pursue
one course which will be applicable in every case, — the rule generally
adopted by surgeons in all operations for inguinal hernise, is to
carry the incision through the neck of the sac directly upwards from its
middle.
FEMORAL HER.XIA. UPPER PART OF THIGH. 1031
OF THE PARTS CONCERNED IN FEMORAL HERNIA.
The hernia distinguished as ' femoral ' leaves the abdomen at the groin,
under the margin of the broad abdominal muscles, and upon the anterior
border of the hip-bone, immediately at the inner side of the large
femoral blood-vessels. After passing downwards for about an inch or less,
the hernia turns forwards to the fore part of the thigh at the saphenous
opening in the fascia lata ; and when it has reached this point the swelling
may be felt and seen.
The muscles of the abdomen, beneath the edge of which the femoral
hernia escapes, are represented by the aponeurotic band of the external
oblique muscle, which is commonly known as Poupart's ligament, but
which, in connection with the ferrnoral hernia, is named the femoral or
crural arch. Extending from the anterior superior iliac spine to the pubes,
this band widens at its inner end, and, inclining or folding backwards, is
fixed to a part of the pectineal line, as well as to the pubic spine of the
hip-bone. The small triangular portion attached to the pectineal line is known
as Gimbernat's ligament (Hey). The outer edge of this part is concave and
sharp ; with other structures, to be presently described, it forms the inner
boundary of the aperture through which the hernia descends. The breadth
and strength of Gimbernat's ligament vary in different bodies, and with
its breadth the size of the opening which receives the hernia will likewise
vary.
The space comprised between the femoral arch and the excavated margin
of the pelvis is occupied by the conjoined psoas and iliacus, with the ante-
rior crural nerve between those muscles, and the external iliac artery and
vein at their inner side. Upon these structures the fascia which lines the
abdomen is so arranged as to close the cavity against the escape of any
part of the viscera, except at the inner side of the blood-vessels. But the
arrangement of the parts situate thus deeply (towards the cavity of the
abdomen) will be most conveniently entered upon after those nearer to the
surface shall have been examined. To this examination we now proceed.
The general disposition of the superficial fascia met with on removing the
common integument from the groin has been described (p. 292). In con-
nection with the present subject it will be enough to mention the following
facts. The deeper layer of this structure adheres closely to the edge of
the saphenous opening, and the careful removal of it is necessary in order
adequately to display that aperture. Where it masks the saphenous open-
ing, the deep layer of the superficial fascia supports some lymphathic
glands, the efferent vessels of which pass through it ; and the small por-
tion of the membrane so perforated is named the cribriform fascia. The
superficial and the deep fasciae adhere together along the fold of the
groin likewise ; and this connection between the two membranes serves the
purpose, at least, of drawing the integument the more evenly into the fold
of the groin, when the limb is bent at the hip-joint.
By Scarpa the deep layer of the superficial fascia which covers the abdomen was
described as an emanation from the fascia lata, extended upwards over the external
oblique muscle.* But different modes of viewing the continuity of such structures
depend very much on the manner of conducting the dissection. In the present case,
for example, the fascia may be said to proceed from above or from below, according
as the parts are dissected from the abdomen downwards, or from the thigh upwards.
* A Treatise on Hernia, translated by Wishart, p. 247.
1032
SURGICAL ANATOMY OF HERNLZE.
Such difference, however, is no more than a verbal one, the material fact being merely
that the two membranes are connected together along the groin.
The separation of the fascia lata into two parts at the saphenous open-
ing, and the position and connections of each part, having been described in
detail, only a few points in the arrangement of this membrane will be
noticed in this place. At the lower end of the saphenous opening the
iliac division of the fascia is continuous with the pubic by a well-defined
curved margin immediately above which the saphenous vein ends ; above
the opening a pointed coriiu (falciform process — Burns*) of the same por-
tion of the fascia extending inwards in connection with the femoral arch
reaches Gimbernat's ligament ; and in the interval between the two points
now referred to (i. e., from the upper to the lower end of the saphenous
opening), the iliac portion of the fascia lata blends with the subjacent sheath
of the femoral vessels as well as with the superficial fascia. The pubic part
of the fascia covers the pectineus muscle, and is attached to the pectineal
ridge of the hip-bone. Immediately below the femoral arch the iliac and
pubic portions lie one before, the other behind, the femoral blood-vessels and
their sheath : they occupy the same position with respect to the femoral
hernia.
Fig. 711.
Fig. 711. — THE GROIN ov THE RIGHT
SlDE DISSEOTKD SO AS TO DISPLAY
THE DEEP FEMORAL ARCH.
1, the outer part of the femoral
arch ; 1', part of the tendon of the
external oblique muscle, including
the femoral arch, and also the inner
column of the external inguiual ring,
projecting through which is seen a
portion of the spermatic cord cut;
2, the femoral arch at its insertion
into the spine of the pubes. The
fibres outside the numeral are those
of Gimbernat's ligament ; 3, the
outer part of the femoral sheath ; 4,
the spermatic cord, after having per-
forated the fascia tra us ver sails; 5,
the deep femoral arch — its inner end
where it is fixed to the pubes ; 6,
internal oblique muscle ; 7, trans-
versalis. Beneath the lower edge of
this muscle is seen the trans versalis
fascia, which continues into the
femoral sheath under the deep femoral
arch; 8, conjoined tendon of the in-
ternal oblique and trans versalis muscles ; 9, a baud of tendinous fibres directed upwards
behind the external abdominal ring.
For an account of the superficial arteries and veins which ramify in the
integument in the neighbourhood of the groin, see pp. 437 and 475.
* Edinb. Med. and Surg. Journal, vol. ii. p. 263, and fig. 2.
In the first edition of Key's Practical Observations in Surgery, the upper end of this
process of the fascia was named the "femoral ligament ;" and since then several anato-
mists have distinguished the same part as " Key's ligament." But Mr. Hey dropped the
designation in the subsequent editions of the same work, and there seems no good reason
for continuing it. Compare the original edition (1803), p. 151, and plate 4, with the
third edition (1814), p. 147, aud plates 4, 5, and 6.
FEMORAL ARCH AND RING. 1033
The anterior or iliac part of the fascia lata being turned aside, the sheath
of the femoral vessels will be in view. The sheath is divided by septa, so
that each vessel is lodged in a separate compartment, and the vein is sepa-
rated by a thin partition from the artery on one side and from the short
canal for the lymphatics on the other side. Along the thigh the sheath is
filled by the artery and vein, but behind the femoral arch it is widened at
the inner side. Here it is perforated for lymphatic vessels, and on this
account is said to be "cribriform."* This inner wider part of the sheath
receives the femoral hernia ; and in connection with the anatomical de-
scription of that disease it is designated the femoral canal. At its upper
end the sheath of the vessels is continuous with the lining membrane of
the abdomen — with the fascia trans versalis at its fore part, and with the
fascia iliaca behind.
When the femoral arch is being removed it will be found that a bundle
of fibres springing from its under surface outside the femoral vessels,
extends across the fore p;trt of the femoral sheath, and, widening at its
inner end, is fixed to the pectineal line behind Gimbernat's ligament.
This fibrous band is known as the deep femoral arch. Connected with the
same part of the bone is the conjoined tendon of the internal oblique and
transverse muscles ; the tendon lies before the attachment of the deep
femoral arch. In many cases the last-named structure is not strongly
marked ; and it may be found to blend with the tendon of the muscles
just referred to. JSTot uufrequenfcly it is altogether wanting.
Attention may now be directed to the internal surface of the abdomen.
When the peritoneum has been removed, it will be observed that the fasciae
lining the cavity form for the most part a barrier against the occurrence of
hernia ; for outside the iliac vessels the fascia iliaca and fascia transversalis
are continuous with one another behind the femoral arch. These fasciae
are, in fact, but parts of the same membrane, to which different names
are assigned for the convenience of description, just as distinctive names
are applied to portions of the same artery. But where the iliac artery
and vein occur, the arrangement of the fasciee is different. The vessels
rest upon the fascia iliaca ; and the membranes, instead of joining at an
angle as elsewhere, are continued into the sheath of the vessels in the
manner above described, f
The sheath is closely applied to the artery and vein, so that in the
natural or healthy state of the parts there is no space left for the formation
of a hernia in the compartments which belong to those vessels ; but at the
inner side of the blood-vessels will be found a depression which is occupied
but partly with the lymphatics. This is the femoral ring, the orifice of the
femoral canal.
Femoral ring. — After the removal of the peritoneum, this opening is not
at first distinctly discernible, being covered with the laminated membrane
(subserous) which intervenes between the peritoneum and the walls of the
abdomen. That part of the membrane which covers the ring was found by
* The word "cribriform" being applied to this part as well as to the layer of the
superficial fascia stretched across the sapbenous opening, the two structures are dis-
tinguished in the following manner : — the former is known as the cribriform portion of
the sheath of the vessels, while to the latter is assigned the name of cribriform fascia.
t Some anatomists describe the sheath of the vessels as continued down from the
membranes in the abdomen, while others regard it as an emanation from the fascia of the
thigh, hut continuous with the abdominal fasciae. As this difference in the manner of
viewing the structure in question does not alter the facts in any way, it is quite immaterial
which of tha modes of description is adopted.
1034 SURGICAL ANATOMY OF HERNLZE.
Cloquet to possess in some cases considerable density ; and, from being
the only barrier in this situation between the abdomen and the top of the
thigh, it was named by that observer the crural septum (septum crurale).
But this structure is no more than areolar tissue with enclosed fat, and it
forms oftentimes but a very slight partition. On clearing it away, the ring
is displayed (fig. 346). It is a narrow opening, usually of sufficient size to
admit the end of the fore finger ; the size, however, varies in different
cases, and it may be said to increase as the breadth of Gimbernat's ligament
diminishes, and the converse. It is larger in the female than in the male
body. On three sides the ring is bounded by very unyielding structures.
In front are the femoral arches ; behind is the hip-bone covered by the
pectineus muscle and the pubic layer of the fascia lata ; on the outer side
lies the external iliac vein, but covered with its sheath ; and on the inner
side are several layers of fibrous structure connected with the pectineal
line — namely, Gimbernat's ligament, the conjoined tendon of the two
deeper abdominal muscles, and the fascia transversalia, with the deep
femoral arch. The last-mentioned structures — those bounding the ring at
the inner side — present respectively a more or less sharp margin towards
the opening.
Femoral canal. — From the femoral ring, which is its orifice, the canal
continues downwards behind the iliac part of the fascia lata (its falciform
process), in front of the pubic portion of the same membrane, and ends at
the saphenous opening. It is rather less than half an inch in length ; but
in its length the canal varies a little in different cases.
Blood-vessels. — Besides the femoral vein, the position of which has been
already stated, the epigastric artery is closely connected with the ring, lying
above its outer side. It not unfrequently happens that the obturator artery
descends into the pelvis at the outer side of the same opening, or imme-
diately behind it ; and in some rare cases that vessel turns over the ring to
its inner side. Moreover, an obturator vein has occasionally the same
course ; and small branches of the epigastric artery will be generally found
ramifying on the posterior aspect of Gimbernat's ligament. In the male
body, the spermatic vessels are separated from the canal only by the femoral
arch.
To the foregoing account of the anatomical arrangement of the parts con-
cerned in femoral hernia, may be added certain measurements, showing the
distances of some of the most important from a given point. They are
copied from the work of Sir A. Cooper : * —
MALE. FEMALE.
From the symphysis pubis to the anterior spine of / -„ . ,
the ilium . | 5i mches - 6 mches-
From same point to the middle of the iliac vein . . 2^ ,, ... 2f ,,
,, to the origin of the epigastric artery 3 ,, ... 3£ ,,
,, to the middle of the lunated edge \ 03
of the fascia lata . . . j 6* » — *1 »
,, to the middle of the femoral ring . 2£ ,, ... 2| ,,
Descent of the hernia. — When a femoral hernia is being formed, the
protruded part is at first vertical in its course ; but at the lower end of
the canal, after the passage of about half an inch, it undergoes a change
of direction, bending forward at the saphenous opening ; and, as it
increases in size, it ascends over the iliac part of the fascia lata and the
femoral arch. The hernia thus turns round those structures, passing from
* On Crural Hernia, p. 5.
COVERINGS OF A FEMORAL HERNIA.
1035
behind them to their anterior surface. Within the canal the hernia is
very small, being constricted by the unyielding structures which form
that passage ; but when it has passed beyond the saphenous opening, it
enlarges in the loose fatty layers of the groin ; and, as the tumour
increases, it extends outwards in the groin towards the iliac spine of the
hip-bone. Hence its greatest diameter is transverse.
Fig. 712. — VIEW OF THE RELATION OP
THE VESSELS OF THE GROIN TO A
FEMORAL HERNIA, &c. (from R.
Quain). |
In the upper part of the figure a
portion of the flat muscles of the
abdomen has been removed, displaying
in part the transversalis fascia and
peritoneal lining of the abdomen ; in
the lower the fascia lata of the thigh is
in part removed and the sheath of the
femoral vessels opened : the sac of the
femoral hernial tumour has also been
opened.
a, anterior superior spinous process
of the ilium ; b, aponeurosis of the ex-
ternal oblique muscle above the exter-
nal inguinal aperture ; c, the abdomi-
nal peritoneum and fascia trans-
versalis ; d, the iliac portion of the
fascia lata near the saphenic opening ;
e, sac of a femoral hernia ; 1, points
to the femoral artery ; 2, femoral vein
at the place where it is joined by the
saphenic vein ; 3, epigastric artery and
vein passing up towards the back of
the rectus muscle ; + , placed upon,
the upper part of the femoral vein
close below the common trunk of the
epigastric and an aberrant obturator artery ; the latter artery is seen in this case to pass
close to the vein and between it and the neck of the hernial tumour.
Coverings of the hernia. — The sac which is pushed before the protruded
viscus, is derived from the external fossa of the peritoneum ; except, how-
ever, when the cord of the obliterated umbilical artery is placed outside its
ordinary position, in which case the serous membrane furnishes the sac
from its internal fossa. After the sac, the hernia carries before it the sub-
serous membrane (septum crurale of Cloquet), which covers the femoral
ring, and likewise an elongation from the sheath of the femoral vessels.
These two structures combined constitute a single very thin covering,
known as the fascia propria of the hernia (Cooper). It sometimes happens
that the hernia is protruded through an opening in the sheath, which there-
fore in that event does not contribute to form the fascia propria.
Diagnosis. — Passing over the general symptoms of abdominal hernise and
the means of forming the diagnosis between a hernia and several other dis-
eases with which it is liable to be confounded, — subjects which fall within
the province of treatises on practical surgery, — the observations to be made
in this place may be limited to the anatomical circumstances which charac-
terise femoral hernia, and serve to distinguish it from the inguinal form of
the complaint. When the inguinal hernia descends to the scrotum or to
the labiuin pudendi, and when the femoral hernia extends some distance
1036 SURGICAL ANATOMY OF HEENL2&
outwards in the groin, no error in diagnosis is likely to arise. It is only in
distinguishing between a bubonocele and a femoral hernia of moderate size
that a difficulty occurs. The position of the femoral hernia is, in most
cases, characteristic. The tumour is upon the thigh, and a narrowed part,
or neck, may be felt sinking into the thigh near its middle. Besides, the
femoral arch is usually to be traced above this hernia, while that band is
lower than the mass of a tumour lodged in the inguinal canal. At the
fcame time the inguinal tumour covers the femoral arch, and cannot be
withdrawn from it like a femoral hernia, when it has turned over that cord.
Some assistance will be gained, in a doubtful case, from the greater facility
with which the tumour emerging at the saphenous opening admits of being
circumscribed, in comparison with the bubonocele, which is bound down by
a more resistent structure — the aponeurosis of the external oblique muscle.
Other practical applications of the foregoing anatomical observations come
now to be considered.
The taxis. — During the efforts of the surgeon to replace the hernia, the
thigh is to be flexed upon the abdomen and inclined inwards, with a view
to relax the femoral arch ; the tumour is, if necessary, to be withdrawn
from over the arch, and the pressure on it is to be directed backwards into
the thigh.
The operation. — The replacement of the hernia by the means just adverted
to being found impracticable, an operation is undertaken with the view of
dividing the femoral canal (or some part of it), thereby widening the space
through which the protruding viscus is to be restored to the abdomen, or
with the view of relieving strangulation when the restoration of the part is
not possible or not desirable. Inasmuch as the manner of conducting the
operation chiefly depends on the place at which the constricting structures
are to be cut into, it will be convenient in the first instance to determine
this point ; and with this object we shall inquire into the practicability and
safety of making incisions into the femoral canal at different points of its
circumference. As the hernia rests upon the pelvis, the posterior part of
the canal may at once be excluded from consideration ; so likewise may its
outer side on account of the position of the femoral vein, and also the outer
part of its anterior boundary, because of the presence of the epigastric
artery in this direction. There remains only the inner boundary with the
contiguous part of the anterior one, and through any point of this portion
of the ring or canal an incision of the required extent (always a very short
one) can be made without danger in nearly all cases. The sources of danger
are only occasional ; for the urinary bladder, when largely distended, and
the obturator artery when it turns over the femoral ring — a very unusual
course — are the only parts at the inner side of the hernia liable to be
injured ; while the last-named vessel, when it follows the course just referred
to, and in the male the spermatic cord, are the structures in peril when the
anterior boundary of the canal is cut into towards the inner side of the
hernia (see p. 624 and fig. 291).
Returning now to the steps of the operation : — After it has been ascer-
tained that the urinary bladder is not distended, the skin is to be divided
by a single vertical incision made on the inner part of the tumour, and
extending over the crural arch. When the subcutaneous fat (the thickness
of which is very various in different persons) is cut through, a small blood-
vessel or two are divided, and some lymphatic glands may be met with.
The haemorrhage from the blood-vessels seldom requires any means to
restrain it ; but the glands, if enlarged, retard the operation in some
FEMORAL HERXIA. OPERATIOX. 1037
degree. The fascia propria of the hernia, which succeeds to the sub-
cutaneous fat, is distinguished by its membranous appearance and the
absence of fat. It is very thin, and caution is required in cutting through
it, as the peritoneal sac is immediately beneath : the two membranes are
indeed in contact, except in certain cases to be presently noticed. A flat
director is now to be insinuated between the hernial sac and the inner side
of the fermoral canal, space for the instrument being gained by pressing its
smooth surface against the neck of the hernia. On the groove of the director
so introduced, or under the guidance of the fore finger of the left hand if the
use of the director should be dispensed with, the probe-pointed bistoury is
passed through the canal, and the dense fibrous structure of which it
consists is divided, the edge of the knife being turned upwards and in-
wards, or directly upwards. By the former plan of relieving the stricture,
the parts divided are the following, — viz. , the falciform process of the fascia
lata and the structures fixed to the pectineal line of the pubes, namely,
Gimbernat's ligament, and, it may be, the tendon of the two deep abdominal
muscles, with the fascia transversalis, and the inner end of the deep femoral
arch ; while if the incision be directed upwards, the falciform process of the
fascia lata and the two femoral arches are divided. The opening being
sufficiently dilated, the protruded part is restored to the abdomen as with the
taxis.
But it may be found necessary to lay open the hernia! sac in order to
examine its contents, or in order to relieve the impediment to the return of
the hernia if that should happen to reside in the neck of the sac itself. In
this case it will probably be required to add to the vertical incision already
made through the integuments and superficial fascia, another directed out-
wards over the tumour, and parallel with the femoral arch. Such additional
incision is readily made, by passing the scalpel beneath the integument and
fat, and cutting outwards after the skin has been pierced with the point of
the knife. The sac being now opened, the hernia knife is used at the inner
side of its neck, while the bowel is guarded with the left hand. During the
restoration of the protruded parts, some advantage will be gained if the
edges of the divided sac should be held down with a pair or two of forceps
in the hands of an assistant.
In the foregoing observations, it has been stated that the fascia propria
is in contact with the sac of the hernia, except in certain cases. The
exception is afforded by the interposition of fat, and sometimes in consider-
able quantity. The adipose substance is deposited in the subserous mem-
brane ; it has the peculiarity of resembling the fat lodged in the omentuin,
and it is occasionally studded with small cysts, containing a serous fluid.
The hernia will be most readily found in such circumstances behind the
inner part of the adventitious substance ; which should be turned outwards
from the inner side, or cut through.
III.— THE PERINEUM AND ISCHIO-RECTAL REGION.
A connected view of the structures which occupy the outlet of the pelvis
becomes necessary, in consequence of the important surgical operations occa-
sionally performed on the geuito-urinary organs and the rectum, which are
contained in that part. In the examination of these structures, which it is
proposed to make in this place, attention will be confined to the male body.
The hip-bones as they bound the outlet of the pelvis are already
1038
SURGICAL ANATOMY OF THE PERIOEUM.
sufficiently described (p. 97). The anterior portion of the space, which is
appropriated to the urethra and the penis, is named the perinceum. This
part is triangular, the sides being formed by the sides of the pubic arch
meeting at the symphysis pubis, while a line extended between the two
ischial tuberosities represents the base of the triangle. In well-formed bodies
the three sides of the space are equal in length ; but cases occur in which,
by the approximation of the ischiatic tuberosities, the base is narrowed ;
and we may anticipate the practical application of the anatomical facts so
far as to state here, that this circumstance exercises a material influence on
the operation of lithotomy, inasmuch as the incisions required in that
operation, instead of being oblique in their direction, must, in such circum-
stances, be made more nearly straight backwards.
That portion of the outlet of the pelvis which lies behind the perinseum
may be named the ischio-rectal region. It contains the end of the rectum ;
and it is defined by the ischial tuberosities, the coccyx, and the great
gluteal muscles. We shall now proceed to the detailed examination of the
two parts thus mapped out.
The skiu of the perinceum continued from the scrotum, and partaking of
the characters it has on that part, is dark-coloured, thin, and extensible,
loosely connected with the subjacent textures, and in the male body studded
with crisp hairs. Around the anus, it is thrown into folds, which are
necessary to allow the extension of the orifice of the bowel, during the
passage of masses of frecal matter ; and along the middle of the perinseum
the median ridge or raphe of the scrotum is continued backwards to the
anus. By this mark upon the skin, the large triangle in which is comprised
Fig. 713.
Fig. 713. — SUPERFICIAL DISSECTION OP THE PERINEUM AND PART OP THE THIGHS.
a, superficial fascia ; &, accelerator urinse ; c, erector penis ; d, transversus perinaei ; e,
upper point of sphincter ani ; /, the edge of the gluteus maximus; 1, superficial perineal
artery ; 2, superficial perineal nerve.
SUPERFICIAL AND DEEP PERINEAL FASCLZE.
1039
the whole perinseum, is subdivided into two equal parts. To one of these
smaller spaces the operations usually performed for gaining access to the
urinary bladder are for the most part restricted. The skin of the perinseuiu
is provided with numerous sebaceous follicles.
From the muscles of the peringeum the skin is separated by areolar tissue
and fat, except in the neighbourhood of the anus, where the sphincter of
the bowel is immediately in contact with the integument. The deeper part
of the fatty subcutaneous membrane, — the superficial fascia (p. 259), —
taking on a fibrous appearance, has, in a great measure, the same arrange-
ment and characters as the corresponding structure of the groin. With that
membrane the layer is continuous in front through the scrotum, but at
other points it is confined to the perinseum, being fixed laterally to the
sides of the pubic arch, while it is continued posteriorly, beneath the
sphincter ani and in front of the rectum, into the deep perineal fascia.
It is in consequence of these connections of the superficial fascia, that
abscesses do not attain a large size in the perineum, and that urine effused
in consequence of rupture of the urethra does not extend backwards to the
rectum or outwards to the thigh, but continues forwards, and, if an outlet
for its escape should not be afforded by the surgeon, reaches successively
the scrotum, the penis, and the groin above Poupart's ligament. In extreme
cases the extravasated fluid would spread from the position last mentioned
over the anterior part of the abdomen and even to the thorax, its extension
downwards to the thigh being restrained by the attachment of the super-
ficial fascia along the fold of the groin.
Fig. 714.
Fig. 714. — DEEPER DISSECTION OF THE PERINJSUM.
The perineal muscles have been removed and also the fat in the ischio-rectal fossa ; a,
superficial fascia ; b, accelerator urinse ; c, crus penis ; d, the bulb ; e, triangular liga-
ment of the urethra ; /, levator ani ; g, sphincter ; h, tuberosity of the ischium ; Jc, gluteus
maximus ; *, Cowper's gland of the left side ; 1, pudic artery ; 2, superficial perineal
artery and nerve. The inferior hacmorrhoidal arteries and the artery of the bulb are
likewise shown.
1040 SURGICAL ANATOMY OF THE PERIN2EUM.
The muscles brought in bo view by the removal of the superficial fascia are,
on each side, the accelerator urinss, erector penis, and transversus perinsei.
Between these muscles is a depression, in which access may be gained to the
membranous part of the urethra, without wounding the erectile tissues of
the penis, — viz., the corpus spongiosum urethrse with its bulbous enlarge-
ment on the one hand, and the crus of the corpus cavernosum on the other,
covered respectively by the accelerator urinse and the erector penis. Along
this depression is placed the superficial artery of the perinseum, with the
accompanying nerve, and the transverse artery crosses behind it ; at the
bottom of the depression, after the muse alar structure has been turned
aside, the deep perineal fascia is met with.
The last-named membrane, deep perineal or subpubic fascia (p. 260), fills
the upper part of the subpubic arch, and is therefore necessarily triangular
in shape. It consists of two laminae of fibrous membrane, the anterior
being much the more fibrous of the two. The layers are separated by an
interval, in which the constrictor muscle of the urethra (p. 265) is lodged,
together with Cowper's glands and the arteries of the bulb, as well as the
pudic arteries and nerves for a short space. Where it is perforated by the
membranous portion of the urethra, the fore part of the deep perineal fascia
is continuous with the fibrous cover of the bulb and corpus spongiosum
urethrse, so that the fascia does not present a defined edge to the tube
which passes through it. The posterior layer is connected with the capsule
of the prostate gland.
The anterior of the two layers constituting the deep perineal fascia, is the struc-
ture recognised by most anatomical writers as forming the triangular ligament of the
urethra. (See especially Camper, Demonstrationes Anatomico-Pathologicae.) It is
pierced by the urethra, and it alone interferes with the passage of instruments along
the canal.
The structure next met with in examining the perinseum is the levator
ani (its fore part), and immediately under that muscle is the prostate. Of
this gland it is here necessary only to state, as material to the present ob-
ject, that placed before the neck of the bladder (when the perinseum is in
the position required for the performance of lithotomy), around the urethra,
behind and below the arch of the pubes, and above the rectum, the prostate is
supported by the levator ani and the pelvic fascia, — the 'latter descending
from the pubes on its upper surface. It is invested with a fibrous covering,
and on this account the outer surface does not readily yield to a cutting
instrument, while the proper substance of the gland may be incised with
comparative facility. From the increase of its breadth towards the lower
surface, it follows that the greatest extent of incision from the urethra,
without wholly dividing the gland, would be made in a direction outwards
and backwards.
The examination of the prostate by the surgeon is made through the
rectum. It is only through the gut that it can be felt. When the gland
is enlarged, as it commonly is in aged persons, the urethra is raised above
its natural level and elongated. But the augmentation of size may be
partial, affecting one lateral lobe (a rare occurrence), and then the urethra
is inclined to one side ; or the middle and posterior part or middle lobe
may be projected upwards at the orifice of the urethra, so as even to ob-
struct the escape of urine from the bladder. In this last case the point of
the instrument passed along the urethra, must be inclined upwards more
than is required in the healthy condition of the parts, in order that it may
DEEP DISSECTION" OF THE PERINEUM.
1041
be made to enter the bladder over the projection referred to. The part of
the urethra encircled by the prostate admits of considerable dilatation. For
the position of the seminal and other openings into it, reference may be
made to the description of the canal at page 961.
Behind the prostate the neck of the urinary bladder presents itself. Here
the bladder is bound to the pubes at its upper part by the pelvic fascia, the
bauds of which are named its anterior ligaments. Laterally the fascia
Fig. 715. — THE BONES OF THE SUBPUBIC ARCH
WITH THE ANTERIOR PART OP THE DEEP
PERINEAL FASCIA.
In consequence of the connection between the
fascia aud the fibrous covering of the bulb having
been cut, the passage for the urethra appears as a
hole. 1, pubes near the symphysis ; 2, hip-bone
close to its tuberosity ; 3, deep perineal fascia —
its anterior surface.
reaches the organ in question over the side
of the prostate ; and an elongation from
the same membrane extends from side to
side between the bladder and the rectum,
after investing the vesiculse seininales and
vasa deferentia.
Turning attention in the next place to the rectum, which occupies the
irregularly shaped space behind the perinoeum, we shall recall a few parti-
culars respecting it. The lowest or third division of the bowel, which
measures about an inch and a half in length, is directed obliquely back-
Fij?. 718.— THE PELVIC
VISCERA OP THE MALE
SEEN ON THE LEFT
SIDE.
1, the body of the pubes
sawn through ; 2, cor-
pus cavernosum penis ; 2',
corpus spongiosum ; 3,
prostate gland with a
portion of the levator ani
covering its fore part ; 4,
urinary bladder; 5, in-
testinum recbum ; 6, deep
perineal fascia — its two
layers ; 7, cut edge of the
pelvic fascia extending
from the pubes to the
back part of the prostate ;
8, vas deferens ; 8', vesi-
cula seminaiis ; 9, ureter.
The jagged cut edge of the
peritoneum is seen passing
over the bladder and rec-
tum.
Fig. 716.
wards from the fore part of the prostate to the amis ; and, as at the same
time the urethra here inclines forwards with the penis, the space between
the two widens towards the surface of the perinseum. Into this space the
bulb of the corpus spongiosum drops down, occupying it more or less
3 Y
1042
SURGICAL ANATOMY OF THE PERIK3EUM.
according as the erectile tissue is more or less distended. The part of the
rectum now under consideration narrows to its end under the influence of
the sphincters. It is supported by the levatores ani, which are fixed to its
sides, and by the pelvic fascia on the inner surface of those muscles.
From this, its shortest and narrowest part, the intestine sweeps into the
hollow of the sacrum, widening considerably at the same time so as to form
a large pouch. This part, which is known as the second division of the
rectum, has before it the prostate and the urinary bladder with the seminal
vesicles, and above these the recto vesical pouch of the peritoneum. The
Fig. 717.
Fig. 717. — THE PROSTATE GLAND AND BASE OP THE BLADDER EXPOSED IN THE
PERINEUM.
Besides the superficial fascia and the perineal muscles, by the removal of which the
spongy erectile tissue and the crura penis were uncovered, the anterior layer of the deep
perineal fascia was cut away in the preparation for this sketch, and thus the pudic
arteries with their branches for the bulb, and Cowper's glands, have been laid bare. The
rectum, too, having been dissected from its connections and drawn back, the prostate
vesicula seminalis and vas deferens of left side ; 8, a small part of the urinary bladder ;
J>, right dorsal artery, with the artery of the bulb aud Cowper's gland resting against the
inner layer of the deep perineal fascia. The last-named parts are at considerable depth,
but the size within which it was necessary to restrict the drawing, did not admit of the
appearance of depth being sufficiently represented.
rectum and the bladder are in contact with each other only in the small
triangular space intercepted between the seminal vessels and the peritoneum ;
and in this space the bladder may be punctured, in order to evacuate its
contents. In performing the operation, the chief guide to the surgeon is
the prostate. The instrument is to be passed forwards into the bladder
behind this gland ; but care must be taken to regulate the distance from
its margin, so as to avoid wounding, on the one hand, the vasa deferentia
which come into apposition one with another immediately behind if; and,
on the other hand, the peritoneum where this membrane turns from one of
the organs to the other. At the same time it is to be remembered, that by
the inclination of the trocar to either side the seminal vesicles would be
ISCHIO-RECTAL FOSSA.— LITHOTOMY. 1043
endangered. The part of the intestine now under observation rests against
the conjoined levatores ani, the coccyx, and the sacrum.
The lower end of the rectum receives small arteries on each side from the
pudic ; but its principal artery (the superior hsemorrhoidal, the continuation
of the inferior mesenteric, p. 412,) descends behind the organ and ends
in branches about three inches from the anus, which enter the gut and
anastomose in loops opposite the internal sphincter. The veins, like those
of the abdomen generally, are without valves. These vessels are very
liable to enlarge and become varicose ; and this condition is constantly
associated with or even forms a great part of the disease known as
haemorrhoids.
Ischio-rectal fossa. — On each side of the rectum between it and the ischiul
tuberosity is contained a considerable quantity of fat, the space which it
occupies being named the ischio-rectal fossa. This hollow extends back-
wards from the periuasum to the great gluteal muscle ; it is bounded on
the inner side by the levator ani as this muscle descends to support the
intestine, and on the opposite side by the obturator fascia and muscle
supported by the hip-bone. At the outer side and encased in a sheath of
the obturator fascia is the pudic artery with the accompanying veins and
nerve ; and small offsets from these cross the fossa to supply the lower end
of the rectum. The pudic artery, it will be observed, is about an inch
above the lower surface of the tuber ischii, and at the same time, by its
position under that prominence of the bone, it is protected from injury by
incisions directed backwards from the perineum ; but in front of this part
(in the peiinseum proper), inasmuch as the vessel lies along the inner
margin of the subpubic arch, it is here liable to be wounded when the
deeper structures of the periuaeum are incised.
The fossa is narrowed as it reaches upwards into the pelvis ; such nar-
rowing of the space is the necessary result of the direction of the levator
ani, which drops inwards from the fascia on the side of the pelvis, and thus
limits the fossa at its upper end.
LATERAL OPERATION OF LITHOTOMY.
The intention of the operation, as it U usually performed, is to remove
a calculus from the urinary bladder by an opening made through the
perinseum and the prostatic part of the urethra. The incisions to attain
this end are commonly made on the left half of the perinseum : because
this side is most convenient to the right hand of the operator ; but if the
surgeon should operate with the left hand, then the opposite (right) side
of the perinceum would be most convenient.
The position at which the perinagum is to be incised requires careful
consideration. For, if the necessary incisions should be made too near the
middle line of the body, the bulbous enlargement of the corpus spongiosurn
urethras and the rectum are liable to be wounded ; and if, on the other
hand, the perinaeum should be divided towards its outer boundary (the
pubic arch), there is a risk of wounding the pudic artery where that vessel
has reached the inner edge of the bone. The incisions are therefore to be
made through the area of the small perineal spnce in such manner as to
avoid both its sides. Again, as to the length to which the several struc-
tures are to be incised : — The integument and the subcutaneous fatty layer
must be divided with freedom, because, first, the skin does not admit of
dilatation during the removal of the foreign body ; and, secondly, exten-
sive incisions through the structures near the surface facilitate the egress
3 Y 2
1044 SURGICAL ANATOMY OF THE PERINEUM.
of urine, which, after the operation, continues for a time to trickle from
the bladder. But the prostate and the neck of the bladder, on the con-
trary, are to be incised only for a small extent. The reasons for this rule
may be stated as follows. By accumulated experience in operations on the
living body, it has been found that the structures now under consideration,
when slightly cut into, admit of dilatation, so as to allow the passage of a
stone of considerable size, and that no unfavourable consequence follows
from the dilatation. Moreover, when these parts are freely divided (cut
through), the results of lithotomy are less favourable than in the oppo-
site circumstances. The less favourable results adverted to appear to be
due to the greater tendency to infiltration of urine in the subserous
tissue of the pelvis ; and the occurrence of this calamity probably depends
on the fact that, when the prostate has been fully cut through, the
bladder is at the same time divided beyond the base of the gland, and
the urine then is liable to escape behind the pelvic fascia (which it will
be remembered is connected with both those organs at their place of
junction) ; whereas, if the base of the gland should be left entire, the
bladder beyond it is likewise uninjured, and the urine passes forwards
through the external wound.
The steps of the operation by which the foregoing general rules are sought
to be carried out are the following. The grooved staff having been passed
into the bladder (and this instrument ought to be of as large size as the
urethra will admit), and the body or the patient, as the case may be, having
been placed in the usual position — by which position the perinseurn ia
brought fully bafore the operator with the skin stretched out — the first
incision is begun about two inches before the anus, a little to the left of the
raphe of the skin, and from this point it is carried obliquely backwards in a
line about midway between the tuber ischii and the anus, extending a little
way behind the level of the latter. During the incision, the knife is held
with its point to the surface, and it is made to pass through some of the
subcutaneous fatty layer as well as the skin. Now, the edge of the knife
is applied to the bottom of the wound already formed, in order to extend
it somewhat more deeply ; and the forefinger of the left hand is passed firmly
along for the purpose of separating the parts still farther, and pressing the rec-
tum inwards and backwards out of the way. Next, with the same finger passed
deeply into the wound from its middle and directed upwards, the position
of the staff is ascertained, and the structures still covering that instrument
are divided with slight touches of the knife, — the finger pressing the while
against the point at which the rectum is presumed to be. When the knife
has been inserted into the groove of the staff (and it reaches that instrument
in the membranous part of the urethra) it is pushed onwards through the
prostatic portion of the canal with the edge turned to the side of the
prostate, outwards, or, better, outwards with an inclination backwards.
The knife being now withdrawn, the forefinger of the left hand is
passed along the staff into the bladder. With the finger the parts are
dilated, and with it, after the staff has been withdrawn, the position of
the .stone is determined and the forceps is guided into the bladder.
In case the calculus is known to be of more than a moderate size, and the
knife used is narrow, the opening through the side of the prostate may be
enlarged as the knife is withdrawn, or the same end may be attained by
increasing the angle which that instrument, while it is being passed onwards,
makes with the outer part of the staff. And if the stone should be of large
size, it will be best to notch likewise the opposite side of the prostate before
LATERAL OPERATION FOR LITHOTOMY.
1015
the forceps is introduced. The same measure may be resorted to afterwards
should much resistance be experienced when the foreign body is being ex-
tracted. Lastly, this part of the operation (the extraction of the stone)
Fig. 713.
Fig. 718. — VlEW OP THE DISTRIBUTION OF THE ARTERIES TO THE VlSCERA OP THE MALE
PELVIS, AS SEEN ON THE REMOVAL OP THE LEFT Os INNOAIINATUM, &C. (from R. Quain). \
a, left external oblique muscle of the abdomen divided ; 6, internal oblique ; c, trans-
versalis ; d, d, the parts of the rectus muscle divided and separated ; e, psoas magnus
muscle divided ; /, placed on the left auricular surface of the sacrum, points by a line to
tbe sacral plexus of nerves ; </, placed on the os pubis, sawn through a little to the left of
the symphysis, points to tbe divided spermatic cord ; A, the cut root of the crus penis ;
i, the bulb of the urethra ; k, elliptical sphincter ani muscle ; I, a portion of the ischium
near the spinous process, to which is attached the short sacro-sciatic ligament ; m, the
parietal peritoneum ; «, the upper part of the urinary bladder; n, n', the left vas deferens
descending towards the vesicula seminalis ; n", the left ureter ; o, the intestines ; 1, the
common iliac at the place of its division into external and internal iliac arteries ; 2, left
external iliac artery ; 3, internal iliac ; 4, obliterated hypogastric artery, over which the
vas defereus is seen passing, with the superior vesical artery below it ; 5, middle vesical
artery ; 6, inferior vesical artery, giving branches to the bladder, and descending on the
prostate gland and to the back of the pubes ; 7, placed on the sacral plexus, points to the
common trunk of the pudic and sciatic arteries ; close above 7, the gluteal artery is seen
cut short ; 8, sciatic artery cut short as it is escaping from the pelvis ; 9, placed on the
rectum, points to the pudic artery as it is about to pass behind the spine of the ischium ;
9', on the lower part of the rectum, points to the inferior haemorrhoidal branches ; 9",
on the perinseum, indicates the superficial perineal branches ; 9'", placed on the prostate
gland, marks the pudic artery as it gives off the arteries of the bulb and of the crus peuis ;
10, placed on the middle part of the rectum, indicates the superior hsernorrhoidal arteries
as they descend upon that viscus.
should be conducted slowly, so as gradually to dilate the parts without lace-
rating them ; and the forceps should be held with its blades one above the
other.
The Structures divided in the Operation. — In the first incision the integu-
ment and ihe subjacent fatty layer are divided ; afterwards a small part
1046 SURGICAL ANATOMY OF THE PERINEUM.
of the accelerator urinse, and the transversus periueei with the transverse
artery. Then the deep periueal fascia with the muscular fibres between
its Ia3rers, the membranous part of the urethra, the prostatic part of
the canal, and, to a small extent, the prostate itself are successively
incised.
The Blood-vessels : their relation to the incisions. — The transverse artery of
the perinae.uiu with, it may be, the superficial artery of the perinaeum, is the
only aitery necessarily cut through when the vessels have their accustomed
arrangement ; for in such circumstances the artery of the bulb is not endan-
gered if the knife be passed into the staff iu a direction obliquely upwards,
the artery being anterior to the groove of that instrument ; neither is
there a risk of wounding the pudic artery} unless the incisions
through the deep parts (the prostate for instance) should be carried too
far outwards.*
But in some cases the arteries undergo certain deviations from their
accustomed arrangement, whereby they are rendered liable to be wounded in
the operation. Thus, the artery of the bulb when it arises, as occasionally
happens, from the pudic near the tuber ischii, crosses the line of incision
made in the operation, f The arterial branches ramifying on the prostate are
in some instances enlarged, and become a source of haemorrhage^ and the
veins, too, on the surface of that gland, when augmented in size, may give
rise to troublesome bleeding. § Lastly, it should be added that the occa-
sional artery (accessory pudic), which takes the place of the pudic when
defective, inasmuch as it lies on the posterior edge of the prostate, might
be divided if the gland were cut through to its base, and only in this
event. ||
* For reference to some cases in which the pudic artery was divided in lithotomy, see
Crosse's " Treatise on Urinary Calculus," p. 21. London, 1835.
f "The Anatomy of the Arteries," &c., hy R. Quaiu, p. 442, and plate 64f, figs. 1
and 2. A case in which death resulted from divisioa of the artery of the bulb is recorded
by Dr Kerr, in the " Kdinb. Med. and Surg. Journal," July, 1847, p. 155.
J See an essay, entitled "Remarks on the Sources of Hsemonhage after Lithotomy," by
James Spence, in the "Edinburgh Monthly Journal of Medical Science," vol. i. p. 166 ;
1841. Aud "The Arteries," &c., l.y R. Quain, p. 445.
§ "The Arteries," &c., by R. Quain, p. 446, and plate 65, fig. 3.
II Ibid. p. 444, and plate 63. An instance in which fatal consequences resulted from
the division of such an artery has been placed on record. See "Case of Lithotomy
attended with Haemorrhage," by J. Shaw, in " The London Medical and Physical
Jouriwl," vol. Iv. p. 3, with a figure. 1826.
DIVISION III.
DISSECTIONS.
THE object of the following Directions is to serve as a short and simple
guide for the display of the structure of the body by studeiita in dissecting-
rooms, the various organs and their parts being mentioned in the order in
•which they may best be exposed, and such methods being indicated as may
enable each student to obtain the greatest amount of information from his
dissection, and at the same time to prevent interference among the neigh-
bouring dissectors as much as possible.
I. GENERAL MANAGEMENT OF THE DISSECTIONS.
1. In different schools, various plans are pursued in the allotment of
portions of the body to different dissectors. According to the method
'here recommended, the subject is divided into ten parts, five on each
side of the body, which are left in connection with one another until the
dissection is sufficiently advanced to admit of their being conveniently sepa-
rated. The boundaries of the parts are so adjusted, that by their due
observance interference between the different dissectors may be as much as
possible avoided.
2. In the case of a male subject, a day is recommended to be set apart
at the commencement for the dissection of the perinseum. Thereafter, and
in the case of a female subject, immediately on its being brought into the
rooms, the subject is to be placed with the face downwards for four days,
during which time the posterior regions are to be dissected, in so far as
within reach, in the order afterwards mentioned for each part. It is then
to be turned and laid upon its back, when a dissection of the various parts
in front is to be made. The whole dissection is supposed to be completed
within six weeks — the time fixed by the Anatomy Act.
3. The dissection of the head and neck and of the limbs should be begun
at once when the subject is laid upon its face ; that of the abdomen as soon
as it is turned on the back, and the thorax must not be opened until the
upper limbs are removed. The limbs ought not to be removed until the
parts which connect them with the trunk have been fully dissected, and an
opportunity has been given for the examination of the surgical anatomy of
the subclavian artery and the parts concerned in hernia, by the dissectors
of the head and the abdomen ; all of which may be accomplished before the
tenth day. The further dissection of the several parts may then proceed
in accordance with the methods suggested in the special directions.
1048 DISSECTION OF THE HEAD AND NECK.
4. It is to be observed that, although in the special directions all the
organs mentioned are supposed to be brought under review in one dissection,
it may be necessary for the student, in order to obtain a full knowledge of
them, to dissect each of the parts more than once. This is especially the
case with the head and neck. It is incumbent therefore upon the student
to make a selection of different objects in each dissection, under the guidance
of the demonstrator, in order that he may progressively obtain a full view of
the whole.
5. Those students who have not previously dissected, are recommended
to select the limbs for their first and second dissections, after they shall
have obtained a sufficient knowledge of the bones and joints ; and for the
most part, the junior students ought not, in a first or second dissection, to
attempt to expose more than the muscles and the largest vessels and nerves.
In their third and subsequent dissections they will gradually come to make
a more complete display of all the parts.
C. In the dissection of the limbs, no interference between the dissectors
of opposite sides can occur ; but in the head and neck, thorax and abdomen,
there is a necessity for the students who are engaged with the parts of
opposite sides to act in concert. The viscera must be examined by them
together, and it will frequently happen that the dissectors of only one side
can work at the same time. When such is the ca.se, the one dissector should
give his assistance to the other by reading or otherwise ; and it will some-
times be found advantageous for those having the same parts of opposite
sides to m;»ke in concert different kinds of dissections on the opposite sides
of the body ; as for example, to dissect the muscles chiefly on one side, and
the vessels and nerves on the other, or the orbit from above on one side
and in a lateral view on the other, etc.
II. SPECIAL DIRECTIONS FOR THE DISSECTION OF
EACH PART.
I. — HEAD AND NECK.
THE right and left sides of this region constitute each a part. Its dissec-
tion may occupy the full time, or about six weeks ; two hours or more daily
being devoted to it. Its inferior boundary extends from the sternum, along
the clavicle, to the acromion process ; and thence to the spinous process of
the third cervical vertebra. It may be found impossible to follow out in
one part the whole of the dissections indicated below ; and therefore the
dissector ought rather, if his time is limited, to make a selection for repeated
dissections, following, as nearly as possible, the methods described. Many
of the smaller points of detail may be passed over by the junior student ;
and there are some which can only be observed in a favourable condition of
the subject.
1. Integument of the Cranium. — The subject being placed with the face
downwards, during the fir^t two days, the scalp and the back of the neck
(to the third cervical vertebra) are to be dissected ; and while this is being
done, only one dissector should work at a time. An incision is to be made
along the middle line, from the spinous process of the third cervical verte-
bra, forwards over the head, to the root of the nose, and another from
immediately behind the ear to meet the first at the vertex, care being taken
not to cut deeper than through the skin. The flaps of integument thus
marked out are to be reflected from above downwards, the posterior oue fiist.
EXTRACTION OF THE BRAIN. 1049
At the back of the neck the posterior and upper parts of the trapezius
arid steruo-niastoid muscles will be laid bare (pp. 200 and 193) ; and, be-
tween these, a part of the splenius muscle, and, when the trapezius is not
strongly developed, a small angle of the coniplexus muscle will be brought
into view. These muscles are to be left undivided at present. On the
posterior part of the cranium the structures to be examined are the occipital
artery and vein, and the great occipital nerve, which pierces the complexus
and trapezius muscles (pp. 351 and 634) ; the small occipital nerve, which
passes upwards along the posterior border of the sterno-mastoid muscle
(p. 638) ; and, beneath these, the occipital part of the occipito-frontalis
muscle (p. 169), which passes upwards from the superior curved line of the
occipital bone. Behiud the ear are the retrahens auriculam muscle and the
posterior auricular artery and nerve (pp. 353 and 612) ; above the ear
is the attolleus auriculam muscle ; and in front of the ear the attrahens
auriculam muscle connected with the attollens, the temporal artery and vein,
the small temporal branch of the third division of the fifth nerve, and the
superior branches of the facial nerve (pp. 170, 353, 612, and 606). Passing
upwards on the forehead, are the frontal part of the occipito-frontalis muscle,
the frontal vein, the supraorbital and frontal arteries, and the supraorbital
and supratrochlear nerves (pp. 360 and 597).
2. Interior of the Cranium and Brain. — During the third and fourth
days the brain and its membranes are to be removed and studied, and the
interior of the base of the skull dissected to show the sinuses, blood-vessels,
and nerves ; and, if there is time (as may be the case, should the head have
been previously opened), the orbit may be examined from above. To
remove the calvarium, the temporal aponeurosis and upper part of the
temporal muscle having been dissected, let the scalpel be carried round the
cranium from a point a little above the occipital protuberance, so as to pass
across the forehead at about an inch above the orbits ; and having cleared a
small portion of the bone on the circle so made, let the external table of
the skull be sawn through, leaving the inner table undivided. Let the
inner table be cracked completely round by a few smart strokes of the
chisel and mallet, and the calvarium may then be pulled away from the dura
mater which lines it. The superficial aspect of the dura mater having been ob-
served, and the superior longitudinal sinus laid open and inspected (p. 462),
the dura mater is to be divided on a level with the sawn edge of the skull,
excepting where it touches the middle line ; this will permit the arachnoid
membrane and pia mater to be examined, as well as the cerebral veins
entering the superior longitudinal sinus ; and when these veins are divided,
the falx cerebri will be seen dipping down between the cerebral hemispheres.
The falx cerebri is then to be separated from its attachment to the crista
galli and thrown backwards (p. 562).
It will now be in the dissector's option to remove the brain at once from
the body, or to examine it in situ as far as the ventricles. If the latter
plan, which is generally to be preferred, be adopted, the dissectors ought
first to examine the convolutions of the upper aspect of the brain, noticing
the anterior and posteiior cerebral arteries arching respectively backward
and forwards ; they will then slice away the hemispheres to the level of the
corpus callosum, and observe the extent of that structure, its transverse
markings, the raphe and the longitudinal lines (p. 540). They will proceed
by incisions at the sides of the corpus callosum, to open the lateral ventricles
separately, so as to expose their cavities with the anterior and posterior
cornua and the parts lying on their floor : they must afterwards cut across
1050 DISSECTION OF THE HEAD AND NECK.
the corpus callosum near the forepart, and raising it carefully, divide with
scissors the septum lucidum which separates the lateral ventricles, and
notice between its layers the fifth ventricle. The lateral ventricles having
been thus thrown into one, the structures forming their floor are more fully
seen, viz., the corpora striata, teeniaa semicirculares, the optic thalami iu
part, the choroid plexus, the upper surface of the fornix, the foramen of
Monro, the anterior and posterior cornua, and the hippocampus minor.
The descending cornu is now to be exposed, on one side only, by cutting
away the cerebral substance above and external to it, and in it will be
found the hippocampus major, pes hippocampi, tseiiia hippocampi, and fascia
dentata.
The fornix is to be divided immediately above the foramen of Monro,
and reflected ; by which means its inferior surface will be brought into
view, as also the upper surface of the velum interpositum. The connections
of the anterior extremity of the velum may then be cut across, and that
structure likewise turned back so as to lay bare the third ventricle ; but iu
doing this care should be taken lest the pineal body, which is adherent to
the under surface of the velum interpositum near its back part, should bo
raised out of its place. The objects seen in and near the third ventricle,
are now to be studied : viz., the optic thalami, the three smaller commis-
sures, viz., anterior, middle and posterior, the pineal body and its crura,
the corpora quadrigemiua, and the anterior opening of the iter a tertio ad
quartum ventriculum ; also the anterior crura of the fornix should be traced
down as far as possible towards the corpora albicantia. The velum having
been replaced, the transverse fissure of the cerebrum ought now to be
opened by division of the remains of the corpus callosum and fornix in the
middle line, and it may be followed in its whole extent to the extremity of
the descending cornu. By this proceeding the veins of Galen will be traced
back through the velum interpositum to the margin of the tentorium, and,
on division of the velum, the valve of Vieussens and the origin of the fourth
nerve, as well as that of the optic tract, may be seen ; but if the view of
these objects should not be satisfactory, they may be again examined after
removal of the brain from the skull.
The remaining part of the brain is to be removed by cutting the teuto-
rium on each side sufficiently to allow the cerebellum to be raised, and
dividing the spinal cord and vertebral arteries as low as possible, the spinal
accessory and suboccipital nerves, and the cranial nerves in order from be-
hind forward, with the infundibulum and internal carotid arteries ; after
which the brain is to be laid on a flat plate with the base uppermost. If,
however, it has been decided to remove the brain entire from the body, this
may either be done in the manner now described, or, with the subject
temporarily placed for the purpose on its back. According to the latter
mode of procedure, which is the most customary, the anterior lobes of the
brain are gently raised, and the olfactory bulbs lifted from the surface of
the ethmoid bone ; the optic nerves, internal carotid arteries, the infundi-
bulum, and the third pair of nerves are successively divided ; the anterior
attachment of the tentorium is then to be cut on each side so as to secure
the divisions of the fourth pair of nerves before they have any chance of
being torn. The tentorium is then to be more extensively divided, and
after it, in their order, the remaining nerves, the vertebral arteries, and the
spinal cord. In studying the base of the brain, the distribution of the
arteries should be first observed, with their union in the circle of Willis
(p. 363). After they are removed, and the less adherent portions of the
THE BRAIN.— ORIGIN OF NERVES. 1051
arachnoid membrane and pia mater are stripped off, except from the angle be-
tween the cerebellum and medulla oblongata, the principal parts of the brain
visible from the base are to be examined. These are : — the fissure of
Sylvius separating the anterior from the middle lobe, and contained in it
the hidden convolutions or island of Reil ; at the entrance of the fissure the
locus perforatus anticus, and terminating in it the inferior part of the trans-
verse fissure of the cerebrum ; also, the crura cerebri emerging from before
the pons Varolii, the anterior extremity of the corpus callosum lying in the
bottom of the great longitudinal fissure, and below it, proceeding backwards
in the middle line, the lamina cinerea, the optic commissure, the tuber
cinereum, the infundibulum, the corpora albicantia, and the locus per-
foratus posticus (p. 536). The principal objects to be noted on the medulla
oblongata are the anterior pyramids with their decussation and the olivary
bodies on the front, and the restiform bodies on its lateral aspect ; pos-
teriorly are the posterior pjramids, and the calamus scriptorius, and its
prolongation downwards into the minute remains of the central canal of the
spinal cord (p. 514). The fourth ventricle, situated between the medulla
oblongata and cerebellum, is now brought into view, and at its sides will be
observed the fringes of pia mater called choroid plexus of the fourth ven-
tricle, the two small lobules of the cerebellum at the sides of the medulla
oblongata named the flocculi or subpeduncular lobes, and behind them the
amygdalae ; while above the medulla are the parts belonging to the middle
lobe of the cerebellum, afterwards more fully noticed (p. 521).
The origins of the cranial nerves may next be examined. The first pair
or olfactory tracts and bulbs are seen on the anterior lobes, and should be
traced back to the white strise by which they arise at the inside of the
fissure of Sylvius ; the second and fourth nerves are seen passing round the
crura cerebri, the optic tracts from the corpora quadrigemina, optic thalami,
and corpora geniculata, the fourth nerve from the valve of Vieussens ; the
third pair lying close together on the inner aspects of the crura cerebri ;
the fifth pair emerging by two roots from the front of the pons Varolii ; the
sixth in front of the anterior pyramids ; the seventh nerve in two parts,
the portio dura and portio mollis, in the angle between the medulla ob-
longata, pous Varolii, and cerebellum ; the eighth pair in three parts, the
glosso-pharyngeal, vagus or pneumo-gastric, and spinal accessory, in front of
the restiform body ; the ninth pair in front of the olivary body ; and the
suboccipital (or first cervical nerve of some authors) close below the ninth
(p. 583). The cerebellum is to be separated from the structures to which
it is attached by division of its superior, middle and inferior crura. The
general disposition of its convolutions and the superior vermiform process
will be noted, as also the parts entering into the formation of the inferior
vermiform process lying in the vallecula beneath, viz. , the pyramid, uvula,
and laminated tubercle, together with the posterior velum. Sections of the
cerebellum are to be made to exhibit the arbor vitae and the grey centre
known as the corpus dentatum or rhomboideum. In conclusion, sections
may be made of the pons Varolii to show its transverse and longitudinal
fibres, of the medulla oblongata to show the olivary nucleus or corpus den-
tatum, and of the crura cerebri to show the locus uiger.
The venous sinuses, arteries, and nerves in the base of the skull, ought
now to be examined, if there be time, before the subject is turned on its
back. The superior longitudinal sinus, the inferior longitudinal and the
straight sinus (with the veins of Galen entering it), and the poste-
rior occipital sinus, are to be traced to the torcular Herophili ; and the
1052 DISSECTION OF THE HEAD AND NECK.
lateral sinuses from that point to the jugular foramina. The cavernous
sinuses, joined together by means of the circular sinus, are then to be
opened ; and the superior and inferior petrosal sinuses, and the trans-
verse sinus (p. 461). In the vicinity of the cavernous sinus the relations of
the 3rd, 4th, 5th, and 6th nerves are to be exhibited, and also the internal
carotid artery and the Gasserian ganglion (pp. 594 and 359) ; after which
the nerves are to be replaced in situ and protected with cotton dipped in
spirits, that they may be ultimately traced forward in the dissection of the
orbit. The pituitary body is to be removed from its position in the sella
turcica, and its form and structure examined (p. 539).
If the above examination of the sinuses cannot be accomplished, at this
stage of dissection, the interior of the skull must be carefully cleaned, and
protected from the air by replacing the skull-cap or otherwise. The dissectors
must also attend to the preservation of the parts at the back of the neck
before the subject is turned.
3. Cervical Region superficially, and Posterior Cervical Triangle. — It is
essential that within four days after the subject has been laid upon its back,
the dissection of the posterior and inferior triangle of the neck be completed,
so that the third part of the subclavian artery may be seen to advantage
before the clavicle and the vessels and nerves of the superior extremity are
divider] .
With this view, a superficial dissection is advised of the whole cervical
region. Make an incision in the middle line from the sternum to the
chin ; another from the acromion, along the clavicle, to the sternum ; and
a third from the chin to the back of the ear ; and let the flaps so obtained
be reflected backwards ; care being taken not to injure the fibres of the
platysma myoides, nor the nerves which lie in the superficial fascia. The
platysma is to be examined and reflected upwards (p. 178) ; after which,
let the external and anterior jugular veins be laid bare, and also the cuta-
neous branches of the cervical plexus of nerves, viz. : — superiorly, the super-
ficial cervical, great auricular, and small occipital nerves ; and, iuferiorly, the
suprasternal, supraclavicular, and supra-aero inial nerves : these will be
traced most easily from their line of emergenae at the posterior border of the
stern o-mastoid muscle (pp. 459 and 638). Let the disposition of the deep
cervical fascia also be noted (p. 197).
The dissector will then cut down through the fat at the lower part of the
posterior border of the sterno-mastoid muscle, and uncover the omo-hyoid
muscle, whose posterior belly emerges from behind the sterno-mastoid, and
forms the superior boundary of the inferior division of the posterior triangle.
He will remove the fat and lymphatic glands from the inferior triangle,
until the scalenus anticus muscle is reached, which will serve as a guide to
the t*hird part of the subclavian artery and vein, and the superior trunks of
the brachial plexus of nerves (pp. 366 and 643). Besides these structures,
the dissector will observe, while engaged with this space, if the sterno-
mastoid muscle be narrow, the phrenic nerve upon the surface of the
scalenus anticus muscle ; he will find the suprascapular nerve and the
small branch to the subclavius muscle both coming from the trunk formed
by the fifth and sixth nerves, the transverse cervical and suprascapular
arteries, and part of the scalenus medius and posticus muscles, as well as the
lower set of the chain of lymphatic glands which lie along' the line of the
sterno-mastoid muscle (pp. 644 and 499), The superior part of the posterior
triangle is next to be dissected by clearing the upper attachments of the
scaleni muscles, with the splenius colli and levator scapulae (p. 177), when
ANTERIOR CERVICAL TRIANGLE. 1053
the arrangement of the cervical plexus will be seen, together -with the Origin
of the phrenic nerve (p. 636) ; also the spinal accessory nerve emerging from
the substance of the sterno-mastoid muscle, and forming connections with
the cervical plexus before it disappears beneath the trapezius muscle (p.
625). The seven cervical and first dorsal nerves are to be cleaned up to
their emergence from the intervertebral foramina, the communicating
branches of the sympathetic nerve being preserved if possible (p. 691); and
the posterior thoracic nerve and the branch to the rhomboid muscles are to
be found (p. 643).
4. Anterior Triangle and Deep parts of the Neck. — Let a dissection of the
deep fascia and of the sterno-hyoid and sterno-thyroid muscles be made in
the middle line between the larynx and sternum, to exhibit the relations of the
trachea as connected with the operation of tracheotomy (p. 888), in particular
noticing the position of the innominate artery, the common carotid arteriess
the thyroid body, the inferior thyroid veins, and the arteria thyroidea ima, if
it be present (pp. 340 and 920). The dissection of the anterior triangle of
the neck is now to be proceeded with, by cleaning the whole of the sterno-
mastoid, sterno-hyoid and sterno-thyroid muscles, and the anterior belly of the
omo-hyoid muscle (p. 191); and in front of the sheath of the great vessels
the descendens noni nerve, with its twigs to the three last named muscles, is
to be laid bare (p. 626). Let the sheath of the vessels be opened, and the
upper part of the common carotid artery exposed, with the pneumo-gastric
nerve and internal jugular vein beside it ; mark the place of its division into
external and internal carotid arteries, and examine the first part of these two
vessels, following the external carotid up to the parotid gland. Let the
digastric and stylo-hyoid muscles be cleaned, and the parts be exposed in the
submaxillary triangle, viz., the superficial part of the submaxillary gland, the
submental branch of the facial artery, and the mylo-hyoid muscle, with the
nerve that supplies it (pp. 183 and 608) ; observe also the ninth cranial or
hypoglossal nerve lying close to the stylo-hyoid muscle, and dissect out its
branch to the thyro-hyoid muscle (p. 627).
The sterno-mastoid muscle is to be divided about three inches from its upper
end, and the superior part is to be dissected quite up to the bone, care being
taken not to cut the spinal accessory nerve which pierces it. The sterno-hyoid
and steruo-thyroid muscles ought now to be divided near their lower end, the
thyroid body dissected, and its form and relations noted. The dissector will
then direct his attention to the branches of the external carotid artery ; he
will dissect the superior thyroid artery and note its sterno-mastoid branch
(already cut), and the hyoid, laryngeal, and crico-thyroid branches ; hewilldis-
sect also the commencement of the ascending pharyngeal artery, the occi-
pital artery as far as the occipital groove of the temporal bone, the posterior
auricular artery, the lingual artery as far as the border of the hyoglossus
muscle, and the facial artery as far as the lower jaw (p. 346) ; he will also lay
bare the pneumo-gastric nerve as far as convenient, tracing the superior and
external laryngeal branches (p. 622).
In the lower part of the neck, the subclavian artery is now to be examined
in the three parts of its course ; and the different relations of the subclavian
and common carotid arteries in the first part of their courses on the two
sides of the body are to be carefully compared (p. 364). The internal
jugular and the subclavian veins, with the branches entering them, are to be
dissected, and on the left side the arched part of the thoracic duct descending
into the angle of junction of these two veins (pp. 459, 469, and 488).
The branches of the subclavian artery are to be displayed, viz., the ver-
1054 DISSECTION OF THE HEAD AND NECK.
tebral and internal mammary arteries, the thyroid axis, from which arise
the inferior thyroid giving off the ascending cervical artery, the supra-
scapular artery, and most frequently the transverse cervical dividing into
the superficial cervical and posterior scapular ; lastly, there are the deep
cervical and superior intercostal arteries coming off either as a single trunk
or separately (p. 3 66). The frequent origin of the posterior scapular artery
from the third part of the subclavian artery and other varieties will here re-
quire to be attended to (p. 372). The trunk of the sympathetic nerve is to
be dissected, with its three cardiac and its other branches, as high as the first
cervical nerve (p. 688) ; and the recurrent laryngeal branch of the vagus
nerve is to be found between the gullet and trachea, and traced up to the
larynx (p. 622).
6. Superficial Dissection of the Face. — In proceeding with this region, the
dissectors ought to expose in concert the superficial muscles of the face on
one side, keeping only the principal blood-vessels and nerves. They ought
likewise to make a more detailed exposure and dissection of these vessels
and nerves on the other side, for which purpose the superficial muscles
must be in some measure sacrificed. If this method cannot be followed
in concert, each dissector must display as much as possible all the parts
on his own side, in which case he will do best to begin with the superficial
muscles.
To exhibit the superficial muscles of the face, the skin is to be reflected
from the middle line, from which one or two such transverse incisions as
shall seem necessary are to be directed outwards. It is most convenient to
begin with the orbicularis palpebrarum muscle, removing the skin from the
circumference to the margin of the eyelids, and dividing it along these
margins (p. 171). The muscles between the eye, nose and upper lip may
then be exposed, the principal of which are these : — the compressor naris,
the levator labii superioris alseque nasi, the levator proprius labii superioris,
and the zygomatici, more deeply the corrugator supercilii, the levator anguli
oris, the pyramidalis nasi continued from the frontalis, the dilatator naris,
<fec. Below the mouth the depressor anguli oris and depressor labii inferioris
will be seen. A more complete view of the orbicularis oris may be obtained
by dissecting it from the inner aspect of the lips ; and the levator menti is
best displayed by making an incision down to the bone in the middle line,
and dissecting outwards.
To expose the nerves and blood-vessels of the face, the sl<in may be reflected
as stated above from the middle line outwards. The surface of the parotid
gland is to be cleaned, and search made for the branches of the facial nerve
as they emerge from underneath its upper and anterior margins (p. 614). The
duct of the parotid gland, and the transverse facial artery, are also to be
dissected (p. 354). The branches of the facial nerve are to be followed for-
ward, and, as far as possible, their connections with the infraorbital, buccal
and inferior labial branches of the fifth nerve are to be traced. Let the
dissector cut the superior attachment of the levator proprius labii supe-
rioris muscle, and, dissecting down upon the infraorbital foramen, follow
out the distribution of the infraorbital nerve and artery emerging from
it (pp. 602 and 357). Let him also cut carefully down upon the mental
foramen, and follow out the inferior labial nerve and artery emerging thence
(p. 608).
The facial artery and vein with their branches are to be dissected out
from the point to which they have been previously traced at the border
of the jaw. The principal branches of the artery, such as the inferior labial,
SUPERFICIAL AND DEEP DISSECTION OP THE FACE. 1055
the superior and inferior coronary, the lateral nasal and the angular, are to
be exposed (p. 350).
The branches of the facial nerve should be traced backwards through the
parotid gland to the emergence of the main trunk from the sty lorn astoid
foramen : while this is being done, the connections of this nerve with the
auriculo-temporal branch of the fifth and with the great auricular nerve will
be preserved, and the twigs to the posterior belly of the digastric muscle and
the stylo-hyoid muscle should be sought for, close to the skull (p. 613). The
continuation of the external carotid artery into the superficial temporal will
be seen ; and, in dissecting out the remains of the parotid gland, the position
and relations of that gland can be studied (p. 814). In this part of the dis-
section, the student should also observe the connections of the part of the
cervical fascia which separates the parotid and submaxillary glands, and which
is continuous with the strong band known as the stylo- maxillary ligament
(p. 197). Finally, the dissector may clean and examine thetarsal and nasal
cartilages (pp. 706 and 771).
6. Deep Dissection of the Face. — The masseter muscle, and the nerve
and artery which enter its deep surface from the sigmoid notch of the lower
jaw are to be examined (p. 181), and the temporal fascia removed, the
orbital twig of the superior maxillary nerve being sought between its layers
(p. 600). By means of the saw and bone-nippers, the zygomatic arch may
then be divided in front and behind in such a manner as exactly to include
the origin of the masseter muscle, which should be turned downwards and
backwards, the masseteric nerve and artery being in the meantime preserved.
Let the coronoid process be divided by a vertical and horizontal incision
with the saw and nippers as low down as possible, care being taken, nob
to cut the buccal nerve, which lies in close contact with the temporal muscle.
The coronoid process with the temporal muscle attached is to be reflected
upwards, and the neck of the jaw is to be divided a little below the con-
dyle, and as much of the rainus of the jaw is to be removed as can be cut
away without injury to the inferior dental artery and nerve which enter
the foramen. The internal maxillary artery with its branches is to be ex-
posed as far as can be done without injury to the external pterygoid muscle,
on. whose outer surface it generally lies ; it is frequently, however, covered
by it. The gustatory and inferior dental nerves will be seen below the
inferior border of the external pterygoid muscle, the latter nerve giving off
the mylo-hyoid branch before entering the inferior dental canal, and resting
on the fibrous slip commonly known as the internal lateral ligament
of the jaw, between which and the jaw the internal maxillary artery
likewise passes. Above the superior border of the same muscle will be
seen the anterior and posterior deep temporal arteries and nerves, arid
between the two parts of the same muscle, the buccal nerve and vessels.
After the external pterygoid muscle has been examined (p. 182), the
temporo-maxillary articulation is to be studied (p. 132), and opened by cut-
ting the external lateral ligament and dividing the capsule of the joint above
and below the interarticular fibro-cartilage, and the condyle of the jaw is to
be disarticulated ; care being taken not to cut the auriculo-temporal division
of the inferior maxillary nerve, which is in close contact with the inner side
of the capsule (p. 606). The external pterygoid muscle may now be turned
forward along with the head of the jaw, and its nerve found ; after which it
may be removed.
The branches of the internal maxillary artery in the vicinity of the ptery-
goid muscles are thus brought fully into view, viz. : in the first part of its
1056 DISSECTION OF THE HEAD AND NECK.
course, the inferior dental, the middle meningeal giving off the small rnenm-
geal artery, the two deep temporal, the pterygoid and other muscular
branches : next, more deeply within the pterygoid muscles, the posterior
superior dental and the infraorbital branches (p. 354). The chorda tympani
nerve is to be dissected upwards to the fissure of Glaser, from its point of
junction with the gustatory nerve under cover of the external pterygoid
muscle, and the branches of the inferior maxillary nerve are to be traced
back to the foramen ovale (p. 605) : the auriculo-temporal nerve will fre-
quently be found embracing the middle meningeal artery. The internal
pterygoid muscle is to be examined as far as it can be laid bare (p. 181).
The auriculo-temporal division of the inferior maxillary nerve is then to be
traced to its distribution, and the pinna of the ear is to be dissected so as to
show the form and extent of its cartilage, the small muscles on its surface,
and the final distribution of its nerves (p. 741).
7. The Orbit. — The dissection of the orbit and the parts pasoing into it
may next be proceeded with. Let a vertical cut be made with the saw
through the frontal bone, near the inner angle of the orbit, immediately
above the fovea trochlearis ; and another from above the ear, downwards
and forwards, through the lateral wall of the skull, towards the sphenoidal
fissure. Remove the outer part of the malar bone with the bone-nippers,
separate carefully with the handle of the knife the periosteum and con-
tents of the orbit from the upper and outer walls, and unite the inner
saw-cut with the sphenoidal fissure, immediately outside the optic foramen,
by means of the chisel ; then, with the bone-nippers, remove the isolated
piece of bone so as to unroof the orbit, and afterwards divide the periosteum
longitudinally, and reflect it. On the upper surface of the contents of the orbit
posteriorly is the fourth nerve, which is to be traced forwards from the cavern-
ous sinus where it enters the orbital surface of the trochlearis muscle, and that
muscle is to be displayed (pp. 594 and 179). The frontal nerve, occupying
the middle of the space, is to be traced back to its origin from the
ophthalmic division of the fifth nerve (p. 597). The lachrymal gland is to
be exposed (p. 709); and from its posterior border the lachrymal nerve is to
be traced back to its origin from the ophthalmic nerve, while at the same
lime its malar branch and palpebral distribution may also be seen. The
levator palpebrss muscle, and the inferior, external, and internal recti
muscles are to be displayed (p. 179), and the ocular surface of each
cleared ; when the sixth nerve will be seen ending in the external rectus,
and branches of the third in the other three recti muscles. These nerves
are now to be traced backwards between the two heads of origin of the
external rectus muscle to the cavernous sinus (pp. 593 and 610). Below
the superior rectus muscle the nasal nerve, derived from the ophthalmic,
will be seen crossing the optic nerve ; it will be followed to the anterior
internal orbital foramen, and its infratrochlear branch traced to the lower
eyelid ; it is then to be dissected back to its origin, and the long and deli-
cate root of the lenticular ganglion sought for on the outer side of the
optic nerve. The ophthalmic or lenticular ganglion is on the outside of the
optic nerve, and may be most easily found by tracing the short and thick
twig which runs into it from the inferior division of the third nerve. In
front of the ganglion its ciliary branches may be seen (p. 599). The
remainder of the fat is to be removed from the lower part of the orbit ;
the distribution of the ophthalmic artery is to be displayed (p. 360) ; and
the lower division of the third nerve is to be traced forwards to the
inferior rectus and obliquus muscles. By a slight dissection from the front
DEEP DISSECTION OF THE FACE. 1057
of the orbit the insertions of these muscles may be more fully displayed.
The contents of the orbit may be afterwards divided behind and turned
forward, to admit of the tensor tarsi muscle and the lachrymal sac being
dissected. Finally, if the subject be favourable, the nasal nerve may be
traced through the ethmoid bone to its distribution in the interior of the
nares, and its external twig to the tip of the nose examined.
8. Deep view of the Fifth Nerve. Spheno-palatine and Otic Ganglia.
Internal Ear. — After the dissection of the orbit has been completed, the
foramen rotundum and infraorbital canal are to be laid open, and the supe-
rior maxillary nerve and its orbital and dental branches dissected (p. 600).
Remove with the saw a further portion of the skull towards the meatus
externus, reaching as far as the foramen spinosum, and with the chisel or
nippers cut down close to the foramen ovale ; remove also a portion of the
bone above the pterygoid processes so as to open up the spheuo- maxillary
fossa, and the spheno-palatine ganglion will be brought into view. The con-
nection of the ganglion with the superior maxillary nerve may then be made
out. Trace the nasal and naso-palatine branches of the ganglion through the
ppheno-palatine foramen, and the palatine branches passing downwards. Lay
open the Vidian canal and dissect the Vidian nerve back to the great
superficial petrosal nerve (p. 603). At the same time the infraorbital,
spheno-palatine, descending palatine, and Vidian branches of the internal
maxillary artery will be noted (p. 356). The otic ganglion may also be
in part seen by breaking open the foramen ovale, following upwards the
nerve of the internal pterygoid muscle, and slightly everting the trunk of
the inferior maxillary nerve (p. 608). The twigs from this ganglion to the
tensor palati and tensor tympani muscles may be found. The otic ganglion,
however, can only be seen to advantage in dissections made from the
inner side of the internal pterygoid muscle and inferior maxillary nerve.
The Eustachian tube may be laid bare in the posterior part of its course,
and may be opened, and the attachment of the tensor tympaui above it
shown (p. 747).
By now sawing the wall of the skull down to the margin of the external
auditory meatus, and removing with the bone-nippers, cautiously, the ante-
rior wall of the meatus externus, the membrana tympani may be exposed ;
and by unroofing the tympanic cavity in continuation of the Eustachian
tube backwards, the malleus, incus, and st ipes, as well as the tendon of the
tensor tympani muscle, will be brought into view (p. 748). The mode of
action of the latter on the membrana tympani may be studied ; also the
chorda tympani nerve will be seen traversing the cavity. The malleus and
incus are to be carefully removed ; then, placing one point of the bone-
nippers in the internal auditory meatus, lay open with the other the vesti-
bule and cochlea, and let the relation of the portio mollis and portio dura
nerves to these cavities be observed (pp. 610 and 615). The manner in
which the stapes fits into the fenestra ovalis may now be seen to ad-
vantage, the tendon of the stapedius muscle requiring, however, to be
cut across before that ossicle can be removed. With the aid of the
bone-nippers, the fleshy part of the stapedius may be laid bare,
descending in the mastoid part of the temporal bone, close to the facial
nerve ; and, in favourable circumstances, the chorda tympani may be traced
back to the facial nerve.
9. Submaxillary and SuUingual Regions. — Let the lower jaw be divided
in front of the masseter muscle, and let the gustatory and mylo-hyoid
nerves be followed from the pterygoid into the submaxillary region. The
3 z
1058 DISSECTION OF THE HEAD AND NECK.
anterior belly of the digastric muscle is to be divided at the chin and
turned down. The mylo-hyoid muscle is to be separated from its fellow
in the middle line and from the hyoid bone, and reflected toward the jaw,
in order to expose the deeper parts. The tongue is to be put on the
stretch by fastening it forward ; the lower jaw is to be divided by a
vertical saw-cut between the first and second incisor teeth, leaving intact
the attachment of the genio-hyoid muscle ; the fragment of loose bone is
to be raised, and the mucous membrane of the mouth slit up to the tip of
the tongue. The dissector will first trace carefully out the gustatory
nerve, where it is in contact with the submaxillary gland, and will exhibit
the submaxillary ganglion connected with it (p. 609). He will then isolate
the submaxillary and sublingual glands, and will observe the relations of
Wharton's duct, the sublingual ducts, and the gustatory and hypoglossal
nerves (p. 816). He will examine the hyoglossus muscle, the genio-hyoid, the
genio-hyoglossus, stylo-glossus, and stylo-pharyngeus muscles (p. 185) ; also
the glosso-pharyngeal nerve (p. 615), and the stylo-hyoid ligament (p. 52).
On dividing the hyo-glossus muscle, the subjacent part of the lingual artery
may be followed into its sublingual and raiiiue branches ; its small hyoid
branch and its branch to the dorsum of the tongue may also be seen ; as well
as those deep branches of the facial artery which have not yet been ex-
amined, viz., the ascending palatine and the tonsillar branches (p. 348).
10. Parts close to the external basis of the Cranium. — If the styloid pro-
cess be nipped through at its base and thrown down with the three styloid
muscles attached, the dissector will be enabled to examine more particularly
the pharyngeal plexus of nerves (p. 690). He may then also examine the
relations of the internal carotid artery and internal jugular vein (p. 359) :
and he will follow up the hypoglossal, spinal accessory, pneumo-gastric,
glosso- pharyngeal, and sympathetic nerves to the basis of the skull ;
examining the connexions of the superior ganglion of the latter with the
other nerves mentioned, and with the anterior divisions of the upper cer-
vical nerves (p. 620). The jugular foramen and the carotid canal are to be
opened into ; and the eighth nerve, and the internal carotid artery with the
carotid plexus accompanying it, are to be followed into the interior of the
cranium (pp. 619 and 688). Before leaving this part of the dissection, the
students dissecting the head ought to make together a complete revision of
all the parts in connexion with the basis of the cranium.
11. Pharynx, Larynx, Palate, Tongue, Nares, <&c. — Let the remains of
the carotid arteries be removed, and the pharynx drawn away from its
loose connection with the upper cervical vertebrae ; and let the base of the
skull be divided between the pharynx and the recti capitis antici muscles ;
then, leaving the neck and back part of the skull for a later examination,
let the pharynx, with the parts in its vicinity, be prepared for dissection by
distending its walls with hair or tow. The constrictor muscles of the
pharynx are to be cleaned and examined, as also the origins of the levator
and circumflexus palati muscles (p. 187). The next step is to open the
pharynx from behind, by an incision in the middle line, and a transverse
one close to the base of the skull ; and to examine the apertures of the
nares, fauces, glottis, oesophagus, and Eustachian tubes (p. 819). The
muscles of the soft palate are then to be dissected ; more particularly the
insertions of the levator and circumflexus palati ; the palato-pharyngeus
and palato-glossus corresponding in position to the posterior and anterior
pillars of the fauces, and in the middle line the azygos uvulae (p. 189). The
Eustachian tube should also be dissected out.
LARYNX.— DEEP MUSCLES, &c., OF HEAD AND NECK. 1059
The larynx and tongue are to be separated from the upper jaw, and the
surface of the tongue and the tonsils examined, as well as such of the
intrinsic muscles of the tongue as may be visible (p. 805). The dissectors
will then proceed to the study of the larynx, carefully cleaning it (p. 905) ;
and after the glottis and true and false vocal cords have been sufficiently
inspected, they may remove the mucous membrane, tracing at the same
time the distribution of the superior and inferior laryngeal nerves, and the
laryngeal branch of the superior thyroid artery. The muscles of the larynx
will then be fully dissected. The crico-thyroid, the arytenoid, the aryteno-
epiglottidean, and the posterior crico-arytenoid muscles can be seen without
injuring the cartilages ; but to expose the lateral crico-arytenoid and the
thyro- arytenoid muscles, it is necessary to remove the upper part of one ala
of the thyroid cartilage. Lastly, the ventricles and pouches of the larynx
are to be examined, the vocal ligaments are to be dissected out, and, the
muscular substance having been removed from the cartilages, their uniting
ligaments, and the joints by which they move on one another, are to be
studied.
In concluding this stage of the dissection, let a vertical section of the
nares and hard palate be made on one side of the septum nasi. Let the
meatus of the nose, the nasal duct, and the maxillary antrum be exa-
mined (p. 773) ; and, if the subject be in good condition, a view may
be obtained of the palatine and naso-palatine branches of the spheno-
palatine ganglion, as well as of the distribution of the descending palatine
artery in the palate (pp. 603 and 357).
12. Deep Muscles and articulations of the Neck and Head. — The
muscles attached to the cervical vertebrae are now to be examined. In
front of the vertebral column, the student will observe the scaleni, lougus
colli, recti capitis antici major and minor, and rectus lateralis muscles
(p. 193) ; then turning to the posterior aspect, he will dissect the remains
of the levator anguli scapulae (p. 203), splenius, trachelo-mastoid, and
complexus muscles to their attachments (p. 234), and notice the portion
of the occipital artery covered by the splenius, with its branch the princepa
cervicis (p. 351). The recti capitis postici major and minor, and the
obliqui capitis superior and inferior, with the suboccipital nerve supplying
them, are to be dissected out (pp. 239 and 632), and the course of the
vertebral artery displayed as it lies in the groove of the atlas (p. 367).
Lastly, the arches of the vertebrae are to be removed, arid the joints and
ligaments examined, especially those between the atlas, axis, and occipital
bone, among which the transverse ligament of the atlas and the crucial
and odontoid ligaments require particular attention (p. 125).
II.— UPPER LIMBS OR SUPERIOR EXTREMITIES.
The right and left limbs constitute each a part. Their dissection
should extend over a period of not less than four weeks. They each
include, along with the limb itself, the axilla or armpit, and the struc-
tures which lie between the trunk of the body and the bones of the
shoulder and arm. The muscles of the back and the spinal cord are also to
be dissected by those having the upper limbs. The omo-hyoid muscle,
however, and the upper parts of the trapezius, levator anguli scapulae,
splenius, trachelo-mastoid, and complexus muscles should be left uninjured
for the dissectors of the head and neck. The inferior boundary of this
part on the trunk of the body is indicated by a line passing along the
3 z 2
1060 DISSECTION OF THE UPPER LIMBS.
outer and lower borders of the latissimus dorsi, the serratus naagnus, and
the pectoralis major muscles.
1. Muscles of the Back; Spinal Cord. — During the first four days, while
the subject is lying on its face, the dissection of the back and spinal cord
below the level of the third cervical vertebra is to be completed. Let an
incision be made in the middle line from the level of the third cervical
vertebra to the sacrum, a second from the acromion to the spine of the
seventh cervical vertebra, and a third from the point where the fold of
the axilla meets the arm to the acromion. If the student be a begirmer,
let him at once dissect out the trapezius muscle in the direction of its fibres
(except the part of it which falls within the boundary of the dissection of
the head and neck), and afterwards the latissimus dorsi, following up its
fibres as close as possible to the tendon of insertion ; but let him not
reflect the skin further than is necessary to exhibit the anterior border of
the latissimus dorsi (p. 200). If the student be a senior, he will, previously
to the dissection of these muscles, also display the cutaneous branches of
the posterior divisions of the spinal nerves, which lie upon their surface
(p. 633).
The trapezius muscle is to be divided by a vertical incision at the dis-
tance of two inches from its vertebral attachment, and on its deep aspect
the spinal accessory nerve and the superficial cervical artery are to be dis-
played (pp. 625 and 373). The rhomboid and levator anguli scapulas
muscles may then be dissected (pp. 202 and 643), and the nerve to the
rhomboids, reaching their deep surface from above. The latissimus dorsi
muscle is to be divided by means of an incision carried along its attachment
to the lumbar fascia from its superior border, at about three inches from its
vertebral attachment, downwards and outwards towards the external
border, leaving uncut the slips attached to the lower ribs and crest of the
ilium. The rhomboid muscles are also to be divided, and the posterior
scapular artery dissected (p. 373). The serrati postici superior and inferior
muscles may then be dissected, and the vertebral aponeurosis seen (pp. 233
and 240) ; after which a view may be obtained of the serratus magnus
muscle from its internal aspect (p. 207).
The posterior serrati muscles and the vertebral aponeurosis may now be
divided, and the dissection of the muscles composing the erector spinae may
be proceeded with (p. 234). Beginning with the ilio-costalis or sacro-lumbalis
muscle, the student will dissect first its six or seven slips of direct insertion
into the lower ribs, then the slips attached to the upper ribs, constituting
the musculus accessorius ad ilio-costalem : he will afterwards turn the
muscle outwards and trace the separate heads of origin of the musculus
accessorius from the lower ribs into their insertions above ; and also the
similar origins of the ascendens cervicis muscle from the upper ribs. He
will next treat the longissimus dorsi muscle in the same manner, dissecting
first the costal insertions on its outer side, and then, having separated it
from the spinalis dorsi muscle (which always requires the division of a
tendon running between the two muscles), make out the insertions into the
transverse processes of the vertebrae. The issue of posterior branches of
spinal nerves, and of intercostal and lumbar vessels, will guide the dissector
to the separation of the masses of muscle (pp. 633 and 404). The con-
tinuation of the long muscles into the ascendens cervicis and transversalis
cervicis, and the origins of the trachelo-mastoid, are then to be traced
upwards in the neck. To see the last-named muscle, however, the splenius
muscle must be dissected and vertically divided ; and the complexus and
DORSAL REGION.— PECTORAL REGION. 1061
semispinalis dorsi and colli muscles may then be examined. Lastly, the
deepest muscles, multifidus spinne, rotatores spinse, interspinales, and inter-
trans versales are to be dissected (p. 238).
At this stage of the dissection a good view may be obtained of the
posterior margins of the obliquus externus and obliquus internus muscles of
the abdomen, and of the posterior and middle layers of the lumbar aponeu-
rosis, which are continuous behind with the trans versalia muscle : the
dissection of these muscles, however, belongs to the abdomen, and they
must not be injured (p. 199).
The next proceeding for a senior dissector is to lay bare the spinal cord ;
for this purpose he will straighten as much as possible the lumbar vertebrae,
by placing blocks underneath the abdomen, and will let the neck hang
slightly downwards. He will then saw through the laminae of the dorsal
and lumbar vertebra on each side, keeping the edge of the saw directed
slightly inwards, and will continue the saw-cuts below on the back of the
sacrum, so as to meet each other where the sacral canal becomes incomplete.
The part so isolated may easily be raised with the chisel, and with the bone-
nippers the whole laminae of the vertebrae may be removed, attached to one
another by their elastic ligaments. In several spaces of the lower dorsal
region the articular processes of the vertebrae may be removed, so as to
expose one or more of the spinal nerves issuing from the canal, and these,
being dissected for a little distance beyond their ganglia, may be afterwards
taken out along with the cord. The theca of dura mater ought now to be
made as clean as possible by removing the fat from its surface, and, after
being examined, should be slit open, that the other membranes and the
relations of the cord may be examined in situ ; more particularly, the
ligamentum deuticulatum, the position of the lower extremity of the cord,
the cauda equina, and the filum terminale will be observed (pp. 502 and
565). The spinal cord and its membranes are then to be removed from
the body and stretched out upon a table, when the anterior and posterior
roots of the nerves and some of the ganglia in connection with the latter
may be observed ; also the external form and structure of the cord, with
the anterior, middle, and posterior columns, the anterior and posterior
fissure, <fec. ; and, lastly, several sections of the cord, in different places,
may be made to exhibit the relations of the grey and white matter within.
2. Pectoral Region and Axilla. — Within four days after the subject has
been laid upon its back, the pectoral region and the axilla are to be dis-
sected. Let a median incision be made in front of the sternum, and from
its upper end let another be carried along the clavicle to the acromion, and
thence downwards to the inside of the middle line of the arm, a little
below the fold of the axilla, and a third horizontally outwards from the
lower end of the sternum. Then let the skin be reflected from the
pectoralis major muscle (p. 203), and let the senior student in doing this
preserve the fibres of the platysma myoides and the suprasternal and supra-
clavicular branches of the cervical plexus of nerves descending over the
clavicle (pp. 170 and 639), the anterior cutaneous branches of the inter-
costal nerves, with the accompanying twigs from the internal mammary
artery near the middle line, and two or three small anterior twigs of the
lateral cutaneous branches of the intercostal nerves appearing round the
lower border of the muscle (pp. 656 and 375). If the subject be a
female, let him also dissect the mammary gland, and in raising the general
integument leave the skin of the nipple, by carrying round it a circular
incision of about two inches in diameter (p. 1002). By raising the skin
1062 DISSECTION OF THE UPPER LIMBS.
within this circle the lactiferous ducts and sacculi will be brought into
view.
Let the clavicular portion of the pectoralis major muscle now be divided
near the clavicle for the examination of the subclavicular space, preserving
the external anterior thoracic nerve as it passes to that muscle (p. 645) ;
and let the costo-coracoid membrane and sheath of the axillary vessels be
examined (p. 229). Then let the sheath be removed, and let the termi-
nation of the cephalic vein and the parts of the axillary artery and vein
brought into view be studied, and also the superior or short thoracic,
acromio-thoracic, and thoracico-humeral branches (pp. 377 and 468).
For the dissection of the axillary space, the skin and the fascia are to
be separately raised from its surface (p. 230), and in the first place the
great vessels and nerves of the limb should be carefully exposed as they
pass from the axilla into the brachial region, but without much disturbing
their position. The axillary aitery and vein are then, to be followed
upwards, and the fat removed from within the space, when the long
thoracic vessels will be found chiefly along the anterior border, the sub-
scapular vessels principally along the posterior border, and the alar twigs
more in the middle. At this stage there will also be seen on the inner
wall of the axilla the intercosto-humeral with other lateral cutaneous
branches of intercostal nerves piercing the serratus magnus muscle (p. 657),
the posterior thoracic nerve descending on the surface of that muscle to
supply it (p. 644), and on the posterior wall the three subscapular nerves
(p. 645). When the axilla has been sufficiently studied, the remainder of
the pectoralis major muscle is to be divided ; the pectoralis minor muscle
also is to be dissected and divided, and the internal anterior thoracic nerve,
which supplies it, is to be found. By this proceeding the axillary vessels
TV ill be exposed in their whole course, and the origins of the branches of
the axillary artery may be more fully examined, viz., the acromio-thoracic,
the alar thoracic, short and long thoracic, and subscapular arteries, and the
anterior and posterior circumflex arteries. Three cords of the brachial
plexus will also be seen ; the outer one giving off the musculo-cutaneous,
the external anterior thoracic, and the outer head of the median nerve ;
the inner giving oft the inner head of the median nerve, the internal
cutaneous nerve, the nerve of Wrisberg, and the ulnar ; the posterior giving
off the three subscapular nerves, the circumflex, and the musculo- spiral
nerve. At this time, after removing the costo-coracoid fascia, the sub-
clavius muscle should be cleaned and examined (p. 206).
On the fourth day after the subject has been placed upon its back, the
clavicle is to be sawn through the middle, or disarticulated at its sternal
end, if this should be recommended by the Demonstrator. The dissector
of the arm may then, in company with the dissector of the head and neck,
on the same side, obtain a continuous view of the upper part of the brachial
plexus, and trace the origins of the suprascapular and posterior thoracic
nerves (p. 641). The axillary vessels and the main trunks of the brachial
plexus of nerves are afterwards to be securely tied together opposite the
outer border of the first rib, and divided above the ligature ; the lower
parts may subsequently be retained in position, by tying them to the
portion of the clavicle left with the arm. The serratus magnus muscle may
now be put upon the stretch, and should be fully studied before the
removal of the arm (p. 207).
3. Scapular Muscles, Vessels, and Nerves. — After the arm has been
removed, the first duty of the dissector is to clean the parts which have
SCAPULAR MUSCLES, &c.— BRACHIAL REGION. 1063
been already laid bare, and to dissect all the cut muscles, so as to bring
their attachments completely into view ; he may then remove the redun-
dant masses which are no longer required, preserving only such portions of
tendons and muscles as may be necessary for subsequent revision of their
relations to the joints and their attachments to the bones. He will then
clean the deltoid muscle, beginning from behind, so as to save as much as
possible the cutaneous branches of the circumflex nerve (pp. 208 anl
645). He will dissect the teres major muscle, and the quadrangular and
triangular intervals which are separated by the long head of the triceps
muscle, and lie between the teres muscle and the scapula ; and he will lay
bare, as far as can be done without injury to the muscles, the structures
which pass through these intervals, viz., iu the upper or quadrangular one,
the circutbflex nerve, with its branch to the teres minor muscle, and the
posterior circumflex artery, and in the lower or triangular interval, the
dorsal branch of the subscapular artery (p. 380). The deltoid muscle is
next to be removed from the whole of its superior attachment, and beneath
it will be seen the bursa that lies between the acromion and shoulder- joint
(p. 138), and the branches of the circumflex vessels and nerve. The
teres minor, iufraspiuatus and supraspinatus muscles are to be dissected
and reflected, and the distribution of the suprascapular nerve and artery
traced. While this is done, neither the deltoid ligament nor acromion
need be divided. The subscapular muscle is likewise to be examined,
with the two short subscapular nerves which supply it ; and on reflecting
this muscle, the subscapular bursa will be observed communicating with
the shoulder-joint. In removing the muscles attached to the scapula, the
student should bring into view the anastomoses of the posterior scapular,
suprascapular, acromio-thoracic, dorsal branch of the subscapular, and the
circumflex arteries. The scapular muscles may then be cut shorb at their
attachments to the humerus.
4. Subcutaneous view of the Arm. — In proceeding with the dissection of
the arm, if the part be in a condition favourable for the purpose, the
dissector may at once display the cutaneous nerves and veins as far as the
wrist (p. 647). He will^ in that case, make an incision all the way down
to the wrist in front of the limb ; or, should it be deemed advisable not to
remove the integument so far, he may terminate his incision half-way down
the fore-arm. For the easier preservation of the cutaneous nerves, which
lie close to the aponeurosis of the limb, he will remove the subcutaneous
fat by reflecting it in the direction from above downwards. The intercosto-
humeral nerve is to be traced down to its distribution (p. 657). The
nerve of Wrisberg and the internal cutaneous branch of the musculo-spiral
nerve will be most easily traced from their deep origins (pp. 646 and 652).
The internal cutaneous nerve will be found piercing the aponeurosis on the
inside of the arm in two separate places, a few inches above the elbow ;
and on the outer side will be found the two external cutaneous branches
of the musculo-spiral nerve, appearing in the line of the external inter-
muscular septum ; while at the bend of the elbow, towards the outer side,
the musculo-cutaneous or external cutaneous nerve will be observed
emerging from the deep parts. Near the elbow, on the inner side, there is
a small lymphatic gland, and on the subcutaneous part of the olecranon a
small synovial bursa. Further down, there may be seen on the inner side
a cutaneous branch from the ulnar nerve, below the middle of the fore-
arm ; on the outer side the radial nerve becoming superficial two or three
inches above the wrist ; and in front the palmar cutaneous branch of the
1064 DISSECTION OF THE UPPER LIMBS.
median nerve immediately above the annular ligament. On the fore-arm
will be found the radial, median and ulnar veins ; in front of the elbow
the median- cephalic and median-basilic veins, together with the deep
median branch ; and in the upper arm the cephalic and basilic veins
(p. 466).
5. Brachial Region more deeply. — The student will now remove the
aponeurosis from the front of the arm. He will first dissect out the
brachial artery with the venae comites clinging to it and intercommunicating
round it, and the median nerve crossing in front (p. 381). Arising from
the inner side of the artery he will find the superior profunda branch
turning backwards with the musculo-spiral nerve, a little further down
the inferior profunda branch accompanying the ulnar nerve, and a little
above the elbow, the anastomotic resting on the brachialis anticus muscle :
while from the outer side of the brachial artery a variety of muscular
branches are observed to spring. The inferior profunda sometimes arises
from the superior profunda branch. Not unfrequeutly two large arteries
will be found in the arm, in consequence of a high division of the main
trunk ; the radial or ulnar artery, most frequently the former, being given
off from the brachial at a higher point than usual, and sometimes even as
high as the axillary artery. In some of these cases the aitery which arifees
out of place lies superficially to the aponeurosis of the limb. The biceps
and coraco-brachialis muscles are next to be dissected, and the deep part
of the musculo-cutaneous nerve, which gives them branches (pp. 212 and
648). The dissector will be careful to preserve the aponeurotic slip of
insertion of the biceps, which lies superficially to the vessels at the bead
of the arm. The aponeurosis is to be removed from the back of the aria,
and the intermuscular septa are to be examined (p. 230) : the triceps
muscle is to be dissected, and the superior profunda artery and musculo-
spiral nerve are to be traced to its outer side (pp. 214 and 652). The
musculo-spiral nerve is to be followed to its division into the radial and
posterior iuterosseous trunks, and its branches, to the brachialis anticus,
supiuator longus and extensor carpi radialis lorigior displayed. The space
in front of the elbow should next be dissected, so as to show the relations
in it of the brachial, uliiar, and radial arteries, with the radial recurrent
and anterior ulnar recurrent branches, and the median and radial nerves
(pp. 389 and 397). The brachialis anticus muscle should also at this time
be fully exposed down to its place of insertion.
6. Shoulder- joint, <£c. — The articulations at the upper part of the arm
ought now to be examined (p. 134). The conoid and trapezoid parts of the
ligaments uniting the clavicle to the coracoid process are first to be dis-
sected, and their uses studied ; then the acromio-clavicular articulation, and
the suprascapular and coraco-acroinial ligaments of the scapula ; lastly,
the shoulder joint is to be dissected, the capsule is to be cleaned, the
ooraco-humeral ligament dissected, and the tendons of muscles in close
relation with the joint examined. When lastly the capsule is opened,
the origin of the long head of the biceps in connection with the gle-
noid ligament will be seen, and also the prolongations of the sy no vial
membrane round the long head of the biceps and beneath the subscapular
muscle.
7. The Fore-arm in front. — Let the aponeurosis be removed from the
front of the fore-arm, and let the five superficial muscles arising from the
inner coudyle of the huinerus be dissected, beginning with the pronator radii
teres ; exhibiting its two heads of origin with the median nerve between
THE FORE-ARM AND HAND. 1065
them, and proceeding successively to the flexor carpi radialis, palmaris
lougus (which, however, is often absent), flexor sublimis digitorum, and flexor
carpi uluaris (p. 215) ; displaying the branches of the median nerve to the
first four muscles, and that of the ulnar nerve to the last-mentioned muscle
and to the flexor profundus digitorum (pp. 651 and 659). The course of the
radial and uluar arteries and nerves in the fore-arm is also to be studied. From
the radial artery (p. 394) will be seen given off the radial recurrent, the
muscular branches, the anterior carpal branch and the superficial volar ;
while arising from the uluar artery (p. 388) will be seen the anterior and
posterior uluar recurrent, and the iuterosseous, dividing into anterior and
posterior interosseous, and giving off the branch to accompany the median
nerve. This last branch, the comes nervi mediani, derives importance from
being not unfrequently developed as a third principal trunk of the fore-arm,
which passes down into the superficial palmar arch. The muscular branches
of the uluar artery, and its anterior and posterior carpal branches, are also
to be exposed. The deep layer of muscles, consisting of the flexor longus
pollicis, flexor profundus digitorum and pronator quadratus, are next to be
dissected (p. 219) ; and along with them, lying on the interosseous mem-
brane, and giving twi^s to the muscles, the iuterosseous branch of the
median nerve, and accompanying it, the anterior interosseous artery (p. 390).
8. The Hand in front — For the dissection of the front of the hand, let
an incision be made down the middle of the palm, a second transversely
through the skin above the division of the fingers, and others down the
middle of each finger. Let the palmar apoueurosis be exposed (p. 231),
preserving the palmaris brevis muscle which is attached to its inner margin
(p. 225) ; and let the skin be reflected from the front of the fingers and
thumb, so as to exhibit the sheaths for the tendons, and the two digital
branches of the artery and nerve on each (p. 218). The palmar apoueu-
rosis is then to be removed, and the trunks of the uluar and median
nerves will be brought into view (pp. 649 and 651), as also the ulnar artery,
the superficial volar branch of the radial artery, and the superficial palmar
arch (p. 393). The short muscles of the thumb, viz., the abductor, opponens,
flexor brevis, and adductor pollicis, are to be dissected, with the twigs of the
median nerve supplying the three first, and the insertion of the flexor longus
pollicis ; then the abductor, opponens, and flexor minimi digiti, with the twigs
of the ulnar nerve supplying them, and its deep branch piercing them (p. 225).
The annular ligament is to be cleaned and the synovial sheath behind it
examined ; the tendons of the superficial and deep flexors are to be followed
to their insertions, and the lumbricales muscles dissected. The deep branch
of the ulnar artery may now be tiaced to the deep palmar arch, and that
of the ulnar nerve to its distribution iu all the interossei, two of the
lumbricales, the adductor pollicis and the inner part of the flexor brevis
pollicis muscle. The deep palmar arch and its branches are also to be fully
examined (p. 400).
9. The Fore-arm and Hand Posteriorly. — For the dissection of the back
of the fore-arm and hand let the remainder of the integument and apo-
neurosis be carefully reflected, and let the distribution of the ulnar and
radial neives to the dorsal aspects of the fingers be traced (p. 653). The
muscles are then to be dissected in the following order, viz., the supinator
longus, extensores carpi radiales longior and brevior, extensor carpi ulnaris,
extensor commuuis digitorum and extensor minimi digiti, the extensor
indicis, the three extensores pollicis, and, lastly, the anconeus and supinator
brevis muscles (p. 220). There will be found passing through the fibres
1066 DISSECTION OF THE THORAX.
of the last-mentioned muscle, the posterior interosseous nerve ; and on,
the interosseous membrane the posterior interosseous artery, with its re-
current branch ; they are both to be traced to their distribution (pp. 654
and 391). The lower part of the radial artery which has hitherto been hid
from view may also now be studied : its posterior carpal and its meta-
carpal branch will be seen, together with the dorsal branches of the
thumb and index finger (p. 398). The termination on the back of the
wrist of the anterior interosseous artery after passing through the inter-
osseous membrane is also to be noticed. Finally, the interossei muscles
are to be dissected on both the palmar and dorsal aspects of the hand
(p. 227).
10. Articulations of the Fore-arm and Hand. — The dissector may now
return to an examination of the elbow-joint and other articulations of the
upper limb. In connection with the elbow-joint, he will first make a revi-
sion of the relations of the soft parts to the joint, such as those of the
triceps, brachialis aiiticus, and supinator brevis muscles, the muscles attached
to the outer and inner condyles of the humerus, and the median, muRculo-
spiral, and ulnar nerves, together with the anastomoses of the superior and
inferior profunda and the anastomotic branches of the brachial, with the two
ulnar, the radial, and the interosseous recurrent arteries. The dissector will
then proceed to examine in detail the internal and external lateral ligaments,
the anterior and the thin posterior ligaments, the orbicular ligament, the syno-
vial membrane, and the cartilaginous surfaces of the bones (p. 138). The
dissector should carefully observe the different kinds of motion of which the
parts are capable, and the variations in the tightness of the ligaments and
in the relations of external parts induced by these motions. In examin-
ing the lower radio-ulnar articulation, the dissector will particularly study
the relations of the triangular fibro-cartilage, and the nature of the move-
ments in prouation and supination of the hand ; and, in the carpal joints,
the extent of the synovial cavities and the position of the cartilage and in-
terosseous ligaments.
III.— THORAX.
The right and left sides of this region constitute each a part. Its dissec-
tion may be completed within three weeks. It includes the deep dis-
section of the thoracic parietes, the viscera of the thoracic cavity,
together with the upper surface of the diaphragm. It is indispensable
that the dissectors of opposite sides should be present together and act in
concert.
1. Parietes and Pleura. — The dissection is to be commenced on the fifth
day after the subject has been placed upon its back, that is, the tenth
day after it has been first placed in the rooms. The external and internal
intercostal muscles, and the intercostal arteries and nerves in the anterior
part of their course, together with the parietal pleura, are to be first dissected
(pp. 240, 402 and 655). Then let the internal mammary artery on the
right side be laid bare by the removal of the 2nd, 3rd, 4th, 5th and 6th
costal cartilages, in order that its relation to the sternum, and its anterior
intercostal and perforating branches may be observed (p. 374). The corre-
sponding costal cartilages on the left side may then be divided close to the
ribs, and the ribs belonging to those cartilages on both sides are then to be
divided as smoothly as possible about three inches beyond their angles ; in
doing which the dissectors must be careful to avoid injuring their hands
upon the sharp spicula of the sawn extremities of the ribs. The anterior
PLEUK^E AND PERICAKDIUM. 1067
limits of the pleural cavities and the position of the anterior mediastinum
can now be examined, together with the position of the heart and great
vessels in relation to the lungs and the walls of the thorax (p. 299). That
this may be done more effectually, the lungs should be inflated through a
tube introduced into the throat or wind-pipe, and their different positions
and relations in the inflated and collapsed state attentively examined. The
body of the sternum is next to be separated from the manubrium, and,
together with the adherent costal cartilages of the left side, removed ; and
on the fragment of the thoracic wall thus separated the triangularis sterni
muscle and its relation to the internal mammary artery may be further
examined. The dissectors will then complete their examination of the
anterior mediastinum, observing in its upper part the remains (if any) of the
thymus body, and will carefully study the remaining reflections of the
pleura. The heart within the pericardium is also to be observed (p.
313). In making this dissection the student may be required to separate
the parietal from the pulmonary pleura, by breaking up with his fingers, or
the handle of the knife, the inflammatory adhesions which are often met
with. Great care must be taken to clean with a sponge and wash the interior
of the chest and the surface of the lungs, first with water, and subsequently
with preserving fluid (p. 892).
2. Parts External to the Pericardium. — The phrenic nerve will be seen
on each side beneath the pleura in front of the root of the lung, and is to be
dissected out ; when its relation to the internal mammary artery, which it
crosses at the upper part of the chest, and the branch of the latter artery
which accompanies it, are to be observed (p. 640). The strustures above the
pericardium are then to be dissected. Foremost will be found the inno-
minate veins and superior vena cava, with the termination of the vena
azygos, and several smaller veins, viz., the inferior thyroid, internal
mammary, superior intercostal, and bronchial veins (p. 453) ; and behind
the veins, the innominate, left carotid, and left subclavian arteries arising
from the arch of the aorta (pp. 340, 341 and 364). The pneumo-gastric
nerves will also be found, that of the right side lying external to the inno-
minate artery, and its recurrent branch turning round behind the subclavian
artery ; and that of the left side passing down in front of the arch of
the aorta, with its recurrent branch winding behind the aorta (p. 618).
Likewise crossing the arch of the aorta, on their way to the superficial car-
diac plexus, will be found the cervical cardiac branch of the left pneutno-
gastric nerve, and, usually, the superior cardiac branch from the sympathetic
nerve on the left side (p. 690). The other cardiac nerves, viz., the cervical
cardiac branch of the right pneumo-gastric nerve, the thoracic cardiac
branches of both pneumo-gastric nerves, the three cardiac branches of the
sympathetic chain of the right side, aud the middle and inferior branches of
the left side, are to be sought on the front and sides of the trachea, as they
pass down to the deep cardiac plexus. The distribution of the pneumo-
gastric nerves is then to be traced to the lungs and oesophagus ; and,
as far as possible, the posterior and anterior pulmonary plexuses are to
be brought into view (p. 623). After that has been done, the roots of
the lungs are to be fully dissected, the relations of the pulmonary arte-
ries and veins and the bronchi observed, and the bronchial arteries traced
to their origins (pp. 897 and 402).
3. Interior of the Pericardium and Heart. — The pericardium having
been examined on its outer aspect, is then to be cut open, and its interior
carefully inspected (p. 300) ; after which it is to be removed, its remains
1068 DISSECTION OF THE THOEAX.
being cleared away from the trunks of vessels entering and emerging
from the heart. The arch of the aorta may now be fully studied,
and the cord of the ductus aiteriosus displayed passing between the
commencement of the left pulmonary artery and the arch of the aorta
(pp. 331 and 382). The students will then proceed to the dissection
of the heart, examining first its external form (p. 302), and afterwards
dissecting the right and left coronary arteries and the .coronary vein (pp.
338 and 482). They will then make an opening into the right auricle,
by means of one incision from the point of entrance of the vena cava
superior to near the entrance of the vena cava inferior, and another from
the auricular appendage to the middle of the first incision. They will remove
and wash out the blood from the right side of the heart, and will particularly
observe in the auricle the arrangement of the musculi pectinati, the annulus
ovalis, the Eustachian valve guarding the vena cava inferior, the orifice of the
coronary vein guarded by the valve of Thebesius, and the foramina Thebesii
(p. 308). When the examination of the right auricle has been completed, the dis-
sector will pass the forefinger of the left hand through the auriculo- ventricular
orifice, and open the right ventricle by two incisions, one along the anterior
border, close to the septum of the heart, prolonged upwards to the com-
mencement of the pulmonary artery, and the other passing from the first,
along the superior border of the ventricle, immediately below the auriculo-
veutricular sulcus, care being taken not to injure the anterior segment of
the tricuspid valve. The principal objects to be noted in this ventricle are
the tricuspid valve with the chordae tendinese and musculi papillares which
act upon it, the other arrangements of columnse carnese, the infundibulum,
and the semiluuar valves of the pulmonary artery on their cardiac aspect.
In exposing the latter, the incision into the ventricle should be carried into
the pulmonary artery between two of the segments of the valve (p. 310).
To examine the left side of the heart, let the inferior vena cava be dissected
a little out of its aperture in the diaphragm, and let it be divided, and the
heart thrown up\\ ards. The left auricle is then to be opened by a transverse
incision near its ventricular margin, and by two short incisions at right
angles to the first ; and after being carefully sponged out, its cavity and
auricular appendage, the remains of the valve of the foramen ovale, and
the entrance of the pulmonary veins on each side will be examined (p.
311). The left ventricle is to be opened by a process similar to that
employed for opening the right ; and after it is carefully cleaned, the
mitral valve and its relation to the aortic orifice, and the cardiac aspect
of the semilunar valves which guard the latter are to be studied (p. 312).
4. Deep Cardiac Nerves, Bronchi, <&c. — The aorta is to be divided
within an inch above its origin, and the first part of the vessel is to be
opened to examine the semilunar valves and the sinuses of Valsalva (p.
307). At this stage of the dissection a fuller examination may be made
of the cardiac neives as they enter the superficial and deep cardiac
plexus : the cardiac ganglion will also be found, and the coronary plexus
traced a short way along the coronary vessels (p. 698). The dissectors
may then divide the trachea an inch or two above its bifurcation, remove
the heart and lungs, and examine more in detail the disposition and struc-
ture of the bronchi (p. 888).
5. Parts in the posterior mediastinum, <&c. — Returning to the thoracic
cavity, the dissectors will examine the oesophagus (p. 821), the descending
aorta with its intercostal branches (p. 401), the main vena azygos, and its
left branch (p.4G9) and, lying between the vena azygos and aorta, the thoracic
DISSECTION OF THE PERINEUM. 1069
duct (p. 487). The thoracic duct may be followed, with the concurrence of
the dissectors of the head and neck, to its termination in the angle of
junction of the left internal jugular and subclavian veins ; and, with the
assistance of the dissectors of the abdomen, it may be also followed down to
its commencement under the crus of the diaphragm. The sympathetic nerve
with its chain of ganglia, is now to be traced over the heads of the ribs and
the vertebral column : its communications with the intercostal nerves are to
be made out, and the splanchnic nerves arising from it dissected (p. 693).
The upper surface of the diaphragm having been cleaned with the knife,
the dissectors of the thorax will examine along with those of the abdomen
the anatomy of this muscle, directing their attention to its various muscular
and tendinous parts, and to the apertures for the passage of the aorta, gullet,
and vena cava infeiior, and observing the distribution of nerves and blood-
vessels in its substance (p. 243).
6. Articulations. — When the dissection of the rest of the thorax has been
completed, the dissectors will, if the subject be favorable, make an examina-
tion of the articulations of the vertebral column and ribs (p. 121). Let
them study, in particular, the anterior and posterior common ligaments, the
intervertebral substance, the ligamenta subflava of the arches, the form and
movements of the articular processes, and the various costo- vertebral, costo-
trans verse and other ligaments. In doing this, the dissectors should make
an attentive examination of the nature and extent of the movements of the
different ribs, and the manner in which they are influenced by the move-
ments of the vertebral column.
IV.— ABDOMEN AND PELVIS.
The right and left sides of these regions constitute each a part. Their
dissection should not be completed in less than four or five weeks. It com-
prehends the examination of the perinaeum and genital organs, the abdominal
parietes over the whole of the external oblique muscles, extending in front
to the linea alba and below to Poupart's ligament, the viscera and deeper
parts of the abdomen and pelvis, and the lower surface of the diaphragm.
1. Perinceum. — If the subject be a male, the first day on which it is in
the rooms will be set apart for the dissection of the perinseum ; and of this
opportunity the dissectors of the abdomen must be prepared to avail
themselves. A lithotomy staff is to be passed into the bladder, and, the
hands and feet having been tied together, the subject is to be placed in the
same position as for the operation of lithotomy, near the edge of the table.
A block is then to be placed below the pelvis, and the scrotum is to be tied
up to the handle of the staff. The body may, however, be still more con-
veniently maintained in the proper position, as is done in some schools, by
means of a simple frame with two upright spokes, behind which the limbs
are placed while the perinteum is projected forwards between them. A
careful incision is to be made in the middle line from the back of the
scrotum to the anus, and, being carried round the margin of the anus, is to
be prolonged as far as the coccyx ; while a transverse incision is to be
directed across the middle line in front of the anus from one ischial
tuberosity to the other. Let the dissector reflect the flaps of skin, exposing
the external sphincter, and clear out the fat completely from the ischio-
rectal fossa of the left side, taking care not to injure the reflection of fascia
which bounds it in front in a line with the central point of the perinseum ;
and let him study the wall* of the fossa (p. 261). On the right side,
1070 DISSECTION OF THE ABDOMEN AND PELVIS.
enough of fat ought to be left in the ischio-rectal fossa to protect the levator
ani and obturator fascia ; the inferior hsemorrhoidal vessels and nerves may
be dissected towards the border of the sphincter (pp. 426 and 672), and the
haemorrhoidal branch of the 4th sacral nerve may be seen emerging from be-
tween the levator ani and coccygeus muscles (p. 668). The two layers of
the superficial fascia in the part of the perinseum anterior to the anus are to
be distinguished, the most superficial corresponding to what may most
correctly be termed the subcutaneous4 adipose tissue, and being continued
over the ischio-rectal fossa, while the deeper layer terminates behind by
dipping deeply in front of that fossa. The most superficial layer having
been removed, the blowpipe may be introduced beneath the deep layer in
the anterior half of the perinsenm, so that, by inflating the connective tissue
underneath it, its external limits, its septum in the middle line, and its
continuity forwards may be demonstrated. It may then be slit open, and
will be found to be attached to the arch of the pubes externally, to be
continuous with the dartos in front, and to be reflected backwards to the
triangular ligament behind (p. 259). Underneath it will be found the
three long scrotal nerves, viz., the two superficial perineal branches of the
pudic and the inferior pudendal branch of the small sciatic nerve, which
are to be traced backwards (pp. 670 and 675) : also the superficial and
transverse perineal arteries are to be dissected out (p. 426). The muscles
on which these structures lie are then to be cleaned, viz., the accelerator
urinse embracing the urethra, the erector penis lying upon the crus penis,
and the transversalis perinsei (p. 264). In the area between these muscles,
subjacent to them, will be observed the triangular ligament or anterior
layer of the subpubic fascia, and its relations, especially to the urethra, are
to be studied (p. 260). It is then to be divided near the bone, and on its
deep aspect the deep transversalis muscle, the constrictor urethrse, and the
artery of the bulb are to be dissected. The deep transversalis muscle is to
be divided, and Cowper's glands are to be sought for in the middle line
beneath (p. 963). On the left side are to be traced out the pudic artery and
nerve ; in doing which the branches of the artery to the bulb and the corpus
cavernosum should be observed (pp. 425 and 670). Lastly, a good view of
the inferior aspect of the prostate gland may be obtained by dividing the
sphincter ani from the accelerator urinse muscles at the central point of the
perinseum (p. 264). Tn the dissection of the periuseum, constant reference
should be made to the bearing of its anatomy on the operations of
lithotomy (p. 1039). At this period, the dissectors may remove one of the
testicles for the sake of dissecting it while fresh.
2. Abdominal wall anteriorly. — The dissection of the abdominal parietes,
in either sex, is to be commenced on the day on which the subject is laid on
its back, with a careful examination of the fascia of the inguinal region, on
each side, as far as Poupart's ligament. This should, if possible, be under-
taken in association with the dissector of the lower limb. An incision is to
be made in the middle line from the xiphoid cartilage to the pubes, avoiding
the umbilicus, and a transverse one meeting the first, inwards from the
anterior superior spine of the ilium. Let the dissector raise the lower of
the two flaps of skin thus marked out, remove the subcutaneous layer of fat
and fascia, and reflect the deeper layer, usually called superficial fascia, in
the same direction as the skin, so as to see the manner in which it is bound
down in the line of Poupart's ligament. Let him at the same time observe
the superficial epigastric and circumflex iliac arteries and veins, and the con-
tinuation of the superficial fascia over the region of the spermatic cord
ABDOMINAL WALL.— INGUINAL REGION. 1071
towards the scrotum in the male, or to the labia in the female (pp. 257
and 437). He will also examine the external abdominal ring, its pillars,
the intercolumnar fascia, and the emergence of the spermatic cord in tha
male, or the round ligament of the uterus in the female (pp. 964 and 986) ;
and he will notice the terminal branches of the ilio-inguinal and ilio-hypo-
gastric nerves (p. 660).
The integument is next to be removed from the upper part of the
abdomen, and along with it the subcutaneous fat ; only a sufficient thick-
ness of superficial fascia being at first left to preserve the cutaneous nerves.
These will be found in two ranges, the one situated near the middle line,
and consisting of the anterior branches of the lower intercostal nerves, the
other range emerging laterally, and consisting of the lateral cutaneous
branches of the same nerves (p. 657). Let the external oblique muscle then
be fully dissected, its posterior border being brought, if possible, into
view (p. 248). The aponeurosis of the external oblique muscle is next to ba
divided by au incision carried transversely inwards from the anterior superior
spine of the ilium, the inferior part of the aponeurosis being left for future
examination ; and the dissector will proceed to separate successively the
attachments of the muscle to the crest of the ilium and each of the eight
lower ribs, and will reflect the muscle towards the middle line as far as it
admits of it. The internal oblique muscle, having next been examined, is to
be reflected in the same way, and the transversalis muscle exposed and
examined (pp. 250, 253).
The deeper parts involved in the descent of inguinal hernia are now to be
studied. For this end, the remaining part of the aponeurosis of the external
oblique muscle is to be divided along its inner attachment, down to the
syrnphysis pubis ; the lower border of the internal oblique muscle is to be
examined, and, in the male, the cremasteric muscular fibres which are con-
tinuous with it are to be followed down to the testicle. The lower parts of
the internal oblique and transversalis muscles are to be successively detached
from Poupart's ligament and turned inwards, and their conjoined tendon is
to be made evident. The fascia transversalis, with the internal abdominal
ring, is now brought into view, and the subperitoueal fat may be seen
shining through it (p. 258). The student will observe particularly the
structures which lie in contact with the spermatic cord in its course from the
internal to the external abdominal ring, and which are described as forming
the walls of the inguinal canal (p. 963). He will also raise the fascia trans-
versalis, and note the infundibuliform fascia and the circumflex iliac and
epigastric arteries (p. 432) ; and will acquaint himself with the relations of
the latter to the direct and oblique varieties of inguinal hernia, and with the
coverings which these hernine receive in their descent (p. 1029).
Poupart's and Gimbernat's ligaments may now be examined from the
deep aspect, and, by separating the subperitoneal fat from the junction line
of the fascia transversalis and fascia iliaca, the student will obtain a view of
the deep crural arch, the crural ring, and the septum crurale (p. 258) —
structures which are to be noted in relation to femoral hernia (p. 1033).
He will then open the sheath of the rectus muscle ; dissect it and the
pyramidalis muscle (p. 253) ; follow the epigastric artery in the substance
of the rectus muscle from below, and the abdominal branch of the internal
mammary artery from above ; and will, at the same time, examine the
deficiency in the lower part of the posterior wall of the sheath of the rectus
muscle, and the semilunar folds of Douglas (p. 250).
3. Male Genital Organs. — If the subject be a male, the penis ought at
1072 DISSECTION OF THE ABDOMEN AND PELVIS.
this time to be dissected. On removal of the skin, the dorsal arteries, vein,
and nerves, together with the suspensory ligament, will be brought into
view (pp. 428, 479, and 671). The corpora cavernosa, corpus spo igiosim,
and glans are then to be dissected ; and the glans may, with care, be sepa-
rated from the corpora cavernosa (p. 956). The pendulous portion of the
penis is to be cut across, the section examined, and the urethra slit open.
The testicles and spermatic cord will next be dissected. The fascia
cremasterica is to be laid open, and the cremasteric branch of the epigastric
artery and genital branch of the genito-crural nerve found (p. 964). The
fascia propria is to be removed, and the elements of the cord examined,
viz., the vas deferens and the spermatic artery, veins, and nerves. The
testicle may then be removed, the tunica vaginalis opened, and the appear-
ance and relations of the epididymis and vas defereus noticed (p. 967).
The caput epididymis, in front of which will be seen the hydatid of
Morgagni, is to be raised from the tunica albuginea, and the epididymis
and coni vasculosi are to be dissected out. The tunica albuginea must then
be divided, and the arrangement of the tubuli seminiferi in the lobules made
apparent under water, and the mediastinum exhibited.
4. Abdominal Cavity ; Peritoneum; Small Intestines, and Colon. — The
cavity of the abdomen is to be opened by a vertical and a transverse incision
crossing one another on the left side of the umbilicus ; but the vertical
incision is, in the first instance, to be arrested at the umbilicus, in order
that the urachus and the fossae into which the peritoneum is thrown by the
obliterated hypogastric arteries may be examined.
The peritoneal cavity, especially the pelvic part, is to be carefully
sponged out and all grumous fluid removed from it, and a piece of cotton
soaked with spirit is to be laid in the recto-vesical fossa ; on the adoption
of these precautions the practicability and comfort of the later parts of the
dissection materially depend. The general arrangement of the viscera is
first to be examined, including the position and relations of the stomach,
spleen, liver, duodenum, jejunum, ileum, ccacum and other parts of the
colon, the rectum, and the kidneys (p. 823). The folds of the peritoneum
are next to be studied (p. 826). This membrane should be followed trans-
versely and vertically throughout the abdominal cavity, and the line of
attachment of the mesentery to the wall of the abdomen should be dis-
played. The disposition of the foramen of Wiuslow and the great omentum
should then be investigated, and, in order that the interior of the sac of the
great omentum may be seen, a transverse cut should be made into it below
the arch of vessels which lies along the great curvature of the stomach, and
by this means the posterior surface of the stomach and the anterior surface
of the pancreas will also be brought into view. When the disposition of
the great omentum has been observed, the small or gastro-hepatic omentum,
the gastro-splenic omentum, the meso-colon, and the relations of the duo-
denum to the peritoneum will be easily followed.
After the study of the peritoneum has been completed, the transverse
colon is to be lifted upwards, and the small intestines turned over to the
left side, in such a manner as to display the whole of the upper or right
side of the mesentery ; and the distribution of the superior mesenteric
artery, from the lower border of the pancreas downwards, with the accom-
panying vein and plexus of nerves, is then to be brought out by dissection
(pp. 410 and 702).
From its right side the artery will be seen to give off the middle colic,
right colic, and ileo-colic branches, and from its left side about a dozen
EXAMINATION OF THE INTESTINES. 1073
branches to the small intestines ; and of these intestinal branches the
dissector may trace the primary, secondary and tertiary arches of anasto-
mosis. If the left branch of bifurcation of the middle colic artery be
followed, it will lead the dissector to the left colic, and so to the trunk of the
inferior mesenteric artery, with its accompanying vein and nerves, situated
to the left of the mesentery ; and to study these the intestines must now
be turned over to the right side. In addition to the left colic, the sigmoid
branch of the inferior mesenteric artery will then also be seen, and the first
part of the superior hsemorrhoidal vessels before they descend into the
pelvis upon the meso-rectum (p. 412).
The dissector will now tie the intestine, a little below the termination of
the duodenum, with two ligatures about an inch and a half distant, and
will divide it between the ligatures ; in like manner he will secure and
divide the great intestine at the lower extremity of the sigmoid flexure : he
will then remove from the body the whole length of intestine between the
upper and lower ligatures. To do this properly, he must begin from above,
and pulling the ligatured extremity upwards with his left hand, with his
right apply the scalpel lightly to the edge of the mesentery, close to the
bowel. By this means the whole small intestines may with ease be re-
moved, and the mesentery left in the abdomen. The large intestine may
now also be removed as far as the rectum. The intestines are to be taken
to the trough, and there they are to be thoroughly cleaned, by having
water run through them from the jejunal end. They may then be spread
out on a table and inflated, iu order that the relative length and diameter
of the different parts may be observed, the arrangement of muscular bands
on the colon, and other facts as to their structure (pp. 840 and 854). The
small intestine is to be separated from the great, several inches above the
caecum. A portion near the upper end may be cut separate, inflated and
dried, in order to show the valvulse conniv elites which are thus put upon
the stretch. The remainder is to be slit open in its whole extent, which
may be best done with a pair of scissors, one of the points of which has
been blunted with a small piece of cork ; the appearance of the mucous
membrane in the different parts is then to be studied, attention being parti-
cularly directed to the distribution of the villi and valvulse conniventes
(p. 842), and to the patches of Peyer's glands (p. 846). The great intes-
tine is next to be divided some inches beyond the csecal valve, and the
remainder is to be slit up and its mucous membrane examined. Lastly,
the caecum is to be very carefully washed, and the structure and action of
the csecal valve studied, by filling the portion of colon with water (p. 852).
The water will be returned although the portion of ileum be left untied, and
the position of the valve when closed may thus be seen. The caecum may
then be slit open on the side opposite the valve, and the vermiform appen-
dage may also be opened to observe its glandular structure.
5. Stoma-ch and Duodenum, Pancreas, Spleen, and Liver. — The duo-
denum and stomach are to be slightly inflated, and the arteries arising
from the coeliac axis are to be dissected (p. 406). The student may begin
by dissecting the splenic artery, following its course to the spleen, and
observing its branches to the pancreas, to the stomach, the vasa brevia, and
the left gastro-epiploic artery. Let him next trace the coronary artery of
the stomach aloug the small curvature of that organ. Then, iu following
out the hepatic artery to its division into right and left branches, he will
find the pyloric branch anastomosing with the coronary artery ; the cystic
branch going to the gall-bladder ; and the gastro-duodenal branch dividing
4 A
1074 DISSECTION OF THE ABDOMEN AND PELVIS.
into the right gastro-epiploic which anastomoses with the left gastt o-epiploic,
and the superior pancreatico-duodenal which anastomoses with the inferior
pancreatico-duodenal branch of the superior mesenteric artery.
The inferior mesenteric vein will be traced upwards behind the pancreas
to join the splenic vein, which, passing transversely onwards to meet the
superior mesenteric vein, will be seen to form with it the trunk of the vena
portse (p. 479). The position of the common bile-duct with reference to
the hepatic artery and portal vein is to be observed, and the duct is to be
traced up into the hepatic and cystic ducts and downwards to the duodenum
(p. 867). The relations and structure of the pancreas are then to be
examined, and the pancreatic duct is to be traced along its posterior aspect
to its termination in the duodenum along with the common bile-duct
(p. 881). The spleen may now be removed, its blood-vessels dissected, a
section made of it, and some of the pulp may be washed away to show the
trabecular structure in the interior of the organ (p. 883). The stomach
may now be removed along with the duodenum, and a careful examination
made of the structure of these organs ; the shape of the stomach, its three
layers of muscular fibres, and the construction of the pyloric valve being
specially noted (p. 830).
The liver is next to be studied. Its ligaments, viz., the falciform liga-
ment, the round ligament or obliterated umbilical vein, the coronary, and
the two lateral or triangular ligaments are first to be examined ; after
which the organ may be removed from the body (p. 8G5). In doing this,
the inferior vena cava must be divided both above and below the liver.
The dissectors may now observe the division of the liver into a right aud
left lobe, as also the quadrate, Spigelian, and caudate lobes : they will like-
wise note the various fissures, viz., the transverse or portal ; the longitudinal
or antero-posterior, divided into an anterior part containing the remains of
the umbilical vein, and a posterior part in which the remains of the ductua
venosus are situated ; the fissure or fossa of the gall-bladder, and the fissure
or fossa of the vena cava (p. 862). They will observe the openings of the
hepatic veins into the part of the vena cava imbedded in the posterior
border of the liver, and follow the divisions of the hepatic arteries, portal
vein and hepatic ducts, as far as possible into the substance of the liver.
In doing this the capsule of Glisson sheathing these parts is to be observed :
the appearance of the substance of the liver may then be exhibited by
minuter dissection ; and the gall-bladder having been opened and washed,
the structure of its coats and the peculiar reticulated arrangement of its
mucous membrane may be examined.
6. Deep Posterior part of the Abdominal Cavity. — On returning to the
examination of the parts remaining in the abdomen, the dissectors will
begin by tracing out the plexuses of the sympathetic nerves. The superior
and inferior mesenteric plexuses, in connection with the aortic plexus, are
to be traced upwards into the solar plexus, and the nerves proceeding from
the aortic plexus downwards into the hypogastric plexus. The solar plexus
will be found surrounding the aorta at the root of the coeliac axis ; also, its
semilunar ganglia, one on each side, and the splanchnic nerves passing
through the crura of the diaphragm to terminate in it (p. 699). The
dissectors will now follow the plexiform nerves which emanate from the
solar plexus and surround the arteries in the neighbourhood ; namely, the
coeliac plexus subdividing into hepatic, splenic and coronary ; also, the
suprarenal and renal, and the spermatic plexuses. In doing this the supra-
renal capsules will fall under observation, and care is to be taken in the
DEEP AND POSTERIOR PARTS OF THE ABDOMEN. 1075
removal of the surrounding adipose tissue not to injure their substance,
which is easily torn (p. 939) : after they have been carefully cleaned, these
bodies may be examined by incisions into their substance.
The aorta and inferior vena cava are then to be dissected, and also the
common and external iliac arteries and veins, together with the kidneys and
ureters. The branches of the aorta to be examined are the inferior phrenic,
the cceliac axis, the superior mesenteric, the suprarenal, the renal, the
spermatic, the inferior mesenteric, the origins of the four pairs of lumbar
arteries, and, continuing the direction of the aorta from its point of bifurca-
tion, the middle sacral artery. The two common iliac arteries and veins
7nust at this time be cleaned, also the ureters ; and the dissection may be
carried down along the external iliac vessels, as far as the origin of the epi-
gastric and circumflex iliac arteries ; in doing which the relations of the
iliac arteries and veins will be carefully observed (pp. 418, 473, and 477).
The position and relations of the kidneys are now to be examined, and
more particularly the position of the renal artery, renal vein, and ureter,
as they enter the gland (p. 926). The kidneys having been removed from the
body, are to be opened by a transverse vertical section, to exhibit the pelvis,
calyces, and pyramids, the cortical and internal tubular substances, and the
Malpighian glomeruli : the fibrous tunic which invests the kidney is also to
be observed. The receptaculum chyli or commencement of the thoracic
duct will be found beneath the right crus of the diaphragm (p. 487), as
also the commencement of the vena azygos in connection with some of the
lumbar veins (p. 469).
7. Upper and Posterior Wall of the Abdomen. — The diaphragm is now
to be dissected (p. 243). Anteriorly will be found its attachments to the
six lower ribs interdigitating with those of the trausversalis muscle ; poste-
riorly will be found the two crura and the ligamenta arcuata externa and
interna ; while the fibres passing from all those parts will be traced to their
connection with the central tendon ; and the openings for the aorta, oeso-
phagus, and vena cava inferior will be examined. The surface of the psoas
magnus muscle is next to be cleaned, as well as that of the psoas parvus
lying superficial to it (if it be present) (p. 272) ; and, emerging from the
fibres of the psoas magnus, the genito-crural nerve will be found and
followed downwards. The nerves of the lumbar plexus will be observed
principally on the outer and inner aspects of the psoas muscles (p. 660).
The fibres of these muscles are to be dissected away from the nerves. In
addition to the communicating branches of the plexus, there will be
observed, proceeding from the anterior division of the first lumbar nerve,
the ilio-hypogastric and ilio-inguinal nerves, often united into one ; from
the second lumbar nerve the external cutaneous and genito-crural nerves ;
from the second, third, and fourth lumbar nerves together, the anterior
crural and the obturator nerves ; and, lastly, the lumbo-sacral cord, formed
by the union of a part of the fourth with the whole of the fifth nerve
(p. 658). On the bodies of the vertebrae will be found the lumbar part of
the chain of sympathetic ganglia ; the branches of communication between
which and the spinal nerves are to be dissected (p. 696).
At this time the dissectors ought to revert to the arrangement of the
posterior part of the trans versalis muscle. This they will find to be con-
tinued into an aponeurosis which is connected behind with three layers ; of
these the most posterior is the fascia lumborum observed in the dissection
of the back, the second lies in front of the erector spinse muscle, and the
foremost is a much thinner membrane placed in front of the quadratus
4 A 2
1076 DISSECTION OF THE ABDOMEN AND PELVIS.
lumborum muscle. The quadratus lumborum and iliacus muscles are now
to be dissected (pp. 255 and 271). On removing the iliacus from the iliac
fossa, the distribution of the ilio-lumbar artery will be traced, and its
anastomoses with the last lumbar and the circumflex iliac artery exhibited
(p. 429).
8. Dissection of the Pelvis. — The pelvis with several of the lumbar verte-
brae ought now to be separated from the rest of the trunk, and before
proceeding further, the dissector should carefully remove the superfluous
masses of muscle and other soft parts adherent to the outer surface of the
bones.
Female Genital Organs. — If the subject be a female, the perinseum is first
to be dissected. The exact position of the orifice of the urethra is to be
examined with reference to the passing of the catheter (p. 980). The fat
is to be removed from between the ischium and rectum ; and, as this is
being done, the inferior hsemorrhoidal and superficial perineal vessels and
nerve will be brought into view (pp. 426 and 670). The sphincter muscles
of the rectum and vagina, the levator ani and transversalis muscles, and the
obturator fascia will be seen (p. 265). From among the fat on the fore
part are to be dissected out the crura of the clitoris and the erector muscles
embracing them ; and on the side of the vulva the bulbus vestibuli. The
glands of Bartholin are to be sought at the back part of the lower end of
the vagina, and the duct of each followed to its orifice by the side of the
hymen or carunculse myrtiformes. Internally to the crus clitoridis, the
triangular ligament or subpubic fascia will be found extending from the
pubic arch to the vagina (pp. 977 and 260).
The bladder ought now to be partially inflated, and the reflections of the
peritoneum in the pelvic cavity examined, especially the posterior, lateral, and
anterior false ligaments of the bladder, and in the female the broad ligament
of the uterus, with the ovary, Fallopian tube, and round ligament (pp. 947
and 985). Let the peritoneum then be reflected from the walls of the pelvis
so as to exhibit the lateral and anterior true ligaments of the bladder, and
the whole internal aspect of the pelvic fasciae (p. 260). In order to have
a complete view of these fasciae, it will be necessary to remove a portion of
the os innominatum of the right side. This must be done in such a manner
as not to interfere with the attachments of the fasciae : while, therefore, the
anterior and lower part of the bone with the acetabulum is to be removed,
the brim of the pelvis and the boundary of its outlet are to be preserved,
as well as the sacro-sciatic foramina. With a little care, and preliminary
observation of the form of the innominate bone, this may be done by means
of a single section with the saw, carried close by the brim of the pelvis, and
downwards in such a direction as to remove the greater part of the thick-
ness of the ischial tuberosity and pass as near as possible to the sacro-
sciatic notches, without breaking into them. By this means the hip joint
may be removed intact ; and, should it not have been dissected along with
the leg, to which it properly belongs, the dissectors of the abdomen will
now have an opportunity of examining it ; and may especially observe the
action of the ligamentum teres, by removing the deep part of the aceta-
bulum, while the capsule of the joint is left intact (p. 151).
Returning to the pelvis, the opening in its lateral wall is to be enlarged,
if necessary, with the bone-nippers, and the obturator internus muscle is to
be carefully removed, and the peculiar arrangement of its tendon remarked
(p. 269). On the inner aspect of that muscle will be found superiorly the
undivided pelvic fascia, inferiorly the obturator fascia, and between the two
PARTS WITHIN THE PELVIS. 1077
the white band stretching from the symphysis pubis to the spine of the
ischium, which marks the level at which the pelvic fascia splits into the
recto-vesical and obturator fasciae ; while in the upper part of the obturator
foramen the obturator vessels and nerve will be seen issuing from the
interior. If the ischio-rectal fossa be now thoroughly cleaned, a complete
view of the layers of fascia will be obtained, and of their relation to the
levator ani muscle (p. 260). The brim of the pelvis is next to be sawn
through near the symphysis pubis, on the side on which the dissection has
been made, and is to be removed. By this means, if the subject be a male,
the relations of the fascia to the prostate gland will be better seen. The
ureters and the vasa defereiitia are to be followed as far as the bladder ; the
sympathetic nerves of the hypogastric plexus are to be traced in their dis-
tribution to the pelvic viscera (p. 702) ; and the branches of the internal
iliac vessels are to be dissected. The internal iliac artery will be found to
give off to the walls of the pelvis and to the external parts, the gluteal, ilio-
lumbar, and lateral sacral arteries, constituting the branches of its posterior
division ; the obturator, internal pudic, and sciatic arteries in connection
with its anterior division : while to the viscera it supplies the superior
vesical with the obliterated hypogastric artery, the inferior vesical giving
the middle hsemorrhoidal, and, in the female, the uterine and vaginal
arteries (p. 420). The first group may perhaps be best seen on the entire
side, and the second and third group on the dissected side of the pelvis.
On the former side the sacral nerves are to be displayed (p. 268), and the
origin of the pyriformis muscle examined. The junction of the luinbo-
sacral cord with the anterior divisions of the three first sacral nerves and a
branch of the fourth, to form the sacral plexus, will now be brought into
view (p. 669). The gluteal nerve will be found arising from the lumbo-
sacral cord (p. 667) ; and arising from the sacral plexus will be found the
great and small sciatic nerves, the pudic nerve, the nerve to the obturator
internus muscle, and other muscular branches (p. 670). The remaining
branches of the fourth sacral nerve will be found to aid the hypogastric
plexus in the supply of nerves to the viscera : at the same time the small
fifth sacral and coccygeal nerves may also be dissected (p. 668). The
coccygeus and levator ani muscles are to be cleaned on their upper aspects,
when they will be seen to form a continuous muscular floor to the pelvic
cavity (p. 262). Tbe chains of sympathetic ganglia are then to be dissected
in front of the sacrum, and, if possible, the lowest parts traced to their
junction in front of the coccyx (p. 696).
9. Pelvic Viscera. — It may be proper to examine the muscular walls of
the bladder in the inflated condition of the organ, before its removal from
the pelvis (p. 944) ; after which the viscera are to be separated from their
attachments to the walls of the pelvis, and removed in one mass.
The rectum may then be carefully dissected away from the rest of the
viscera, the extent of its connection with them being at the same time
observed (p. 856). Its muscular coats having been sufficiently examined, it
is to be slit open and washed, in order that the general appearance and folds
of its mucous membrane may be seen. In the male subject the prostate
gland enveloped in its fibrous covering, the vesiculae seminales, and the vasa
deferentia are to be carefully dissected (pp. 952 and 971) ; the bladder
is to be opened from before, the neck being left in the first instance entire ;
and the openings of the ureters and urethra, with the trigone between
them, are to be examined (p. 948). The prostatic, membranous, and bulbous
parts of the urethra are then to be slit open from above, the varying dia-
1078 DISSECTION OF THE LOWER LIMBS.
meter of the urethra observed, as also in its prostatic part, the verumon-
tanum or caput gallinaginis, the sinus poculads, and the orifices of the
common ejaculatory ducts (p. 901). The junction of the vas deferens and
vesicula eeminalis to form the common ejaculatory duct is to be displayed ;
and a longitudinal section of the prostate gland may be made to show its
thickness, consistence, and structure : the relations of its base to the neck
of the bladder should be particularly observed, with the circle of veins of the
vesical plexus in the angle between them.
In the female subject the bladder is to be opened and examined as in the
male, and the length and diameter of the urethra observed (p. 980). The
vagina is then to be cut open a little on one side of the middle line in front,
when the rugje of its mucous membrane will be seen ; also, at its entrance,
the carunculze myrtiformes, and, projecting into it above, the cervix uteri
(p. 981). The ovary with its ligament and mesovarium, the Fallopian tube,
the round ligament of the uterus, and, between the ovary and Fallopian
tube, the tubules termed parovarium or organ of Rosenmliller, are next to
be dissected, and the external configuration of the uterus examined (p. 982).
The student will then notice the position and appearance of the os uteri
externum, and will open the uterus on its anterior aspect by a line of
section which, by dividing into two superiorly, is prolonged to both of the
cornua (p. 984). He will thus see the size and shape of the triangular
cavity of the uterus, the cavity of the cervix, the rugce of its mucous mem-
brane, and the os uteri internum.
10. The Pelvic Ligaments. — At the conclusion, the articulations of the
pelvic bones may be examined, if they are still in a condition fit for dissec-
tion (p. 147). The symphysis pubis with its concentric laminae of fibro-
cartilage is first to be examined ; then the articulation of the pelvis with
the fifth lumbar vertebra, especially the sacro-vertebral and ilio-lumbar
ligaments : the great and small sacro-sciatic ligaments should be cleaned,
and, by removing the remains of the origin of the obturator interuus muscle,
the obturator membrane.
The anterior and posterior ligaments and the intervertebral disc of the
sacro-coccygean articulation are to be observed : lastly, the strong posterior
and the thinner anterior sacro-iliac ligaments having been dissected, the
last mentioned is to be divided, and the cartilaginous surfaces of the sacro-
iliac synchondrosis are to be brought into view by forcing open the
articulation.
V. —LOWER LIMBS OR INFERIOR EXTREMITIES.
The right and left limbs constitute each a part, the dissection of which
should extend over a period of not less than four weeks. It includes the
whole limb below Poupart's ligament and the crest of the ilium, but not
the perinseum.
1. The Gluteal Region. — The dissection of the gluteal region, the back
of the thigh, and the popliteal space is to be completed in the four days
during which the subject lies on its face. To remove the integument from
the buttock let an incision be carried along the crest of the ilium, brought
downwards in the middle line of the sacrum and curved outwards in the
fold of the nates, then directed obliquely to the outside of the thigh about
five or six inches below the great trochanter. The junior student will at
once proceed to clean the gluteus maxiinus muscle in the direction of its
fibres (p. 266). The senior student will examine the arrangement of the
GLUTEAL REGION. 1079
cutaneous nerves in this region. Of these he will find, descending over the
crest of the ilium, in order from before backwards, the lateral branches of
the last dorsal and ilio-hypcgastric nerves (pp. 658 and 660), with several
branches of the lumbar nerves (p. 634) ; aud, piercing the gluteus maximus
muscle near its posterior attachment, some small cutaneous twigs from the
posterior divisions of the upper sacral nerves (p. 635) ; lastly, turning
round its inferior border, branches from the small sciatic nerve (p. 675).
It will be observed that the fascia lata, which is strongly developed over
that part of the gluteus medius which lies in front of the gluteus maximus
muscle, on reaching the upper border of the gluteus maximus, divides into
two lamina, of which one is continued on the superficial, and the other on
the deep aspect of that muscle (p. 292). Care is to be taken to lay bare
the inferior border of the gluteus maximus in its whole extent ; and a
synovial bursa over the tuberosity of the ischium is to be sought for. The
muscle is then to be divided close to its iliac and sacral attachment, and in
turning it forward, the sciatic artery and the superficial branch of the
gluteal artery will come into view. The branches of these arteries and of
the small sciatic nerve which enter the muscle are to be followed out to
some extent, and they may then be divided to permit the complete reflec-
tion of the muscle. While this is being done, a large synovial bursa will be
found between the trochanter major and the insertion of the gluteus maxi-
mus into the fascia lata.
The fascia lata is to be removed from the upper part of the gluteus
medius muscle, and the parts exposed by the removal of the gluteus maxi-
mus are to be cleaned in their order from above downwards, viz. : the back
part of the gluteus medius muscle, the gluteal vessels (p. 429), the pyriformis
muscle, the sciatic vessels and the great and small sciatic nerves (p. 674), the
gemelli muscles, superior and inferior, with the tendon of the obturator inter-
nus muscle between them (p. 268). The tendon of this muscle may now be
dissected from between the gemelli, divided and turned back, to show the
synovial cavity in which it plays upon the smooth trochlear surface of the
ischium. The quadratus femoris, the tendon of the obturator externus muscle
situated more deeply, the upper part of the adductor magnus muscle, and the
origin of the hamstring muscles are then to be exposed. From the small
sciatic nerve the inferior puclendal branches will be seen given off, in addition
to those already mentioned, and from the sciatic artery, besides muscular
branches, the coccygeal branch, the branch to the great sciatic nerve, and
that by which it anastomoses with the internal circumflex artery may be
traced. On the spine of the ischium also will be seen the pudic vessels and
nerve, and the nerve to the obturator internus muscle (pp. 425 and 670) ;
and descending under cover of the tendon of the obturator internus and the
gemelli is the small nerve to the quadratus femoris.
The gluteus maximus muscle having been entirely removed from its upper
attachment, and the tendon of insertion being left, the gluteus medius is to
be raised from the ileum in three-fourths of its extent ; its anterior border
and that of the gluteus minimus muscle being left for dissection from the
front. The attachments of the gluteus medius muscle are to be observed,
as also the superior and inferior deep branches of the gluteal artery, and the
distribution of the gluteal nerve (pp. 429 and 667). The posterior part of
the gluteus minimus may then be raised from the ileum to show the extent
of its attachment to that bone, and its relation to the capsule of the hip-
joint.
2. The Popliteal Space. — It is advisable to dissect this space before the
1080 DISSECTION OF THE LOWEK LIMBS.
posterior femoral region. In order to open it the integument may be
divided by a longitudinal incision of considerable length, which may be
crossed if necessary by a transverse one in the middle of the space, sufficient
to allow the integument to be thrown freely back. On removal of the
superficial fat, the fascia lata, which is strong in this region, will come into
view, and, in the lower part of the space, the terminal twigs of the small
sciatic nerve (p. 675), and the upper part of the short saphenous vein (p. 476).
The fascia lata is to be divided, and the fat carefully removed from the
space, its boundaries cleaned, and the vessels and nerves with their branches
traced. Superiorly the biceps muscle on the outside, and the semiteudiuosus
and semimembranosua muscle on the inside, and inferiorly the heads of the
gastrocnemius muscle with the small belly of the plantaris will thus be
exposed.
Lying in the space the dissector will find the external and internal pop-
liteal nerves giving off their articular and sural branches (pp. 676 and 679),
and more deeply the popliteal vessels in a common sheath (p. 441). He will
follow out the branches of the popliteal artery, viz., its five articular branches,
the superior, azygos, and inferior, and its sural branches. On the surface
of the popliteal artery, where it enters the space, may be found a twig of the
obturator nerve (p. 663).
When the dissection of the popliteal space has been completed, it is to be
united to that of the gluteal region by an incision along the posterior part
of the thigh. The course of the small and great sciatic nerves will thus be
laid bare, together with the biceps, semitendinosus, and semimembranosus
muscles, the twigs of the great sciatic nerve supplied to these muscles, and
to the adductor magnus, and the four perforating branches of the deep
femoral artery (p. 439) ; the posterior aspect of the adductor maguus muscle
will also be exposed.
3. The Front of the Thigh. — On the day on which the subject is laid upon
its back, the student should begin the dissection of the front of the thigh,
by studying the fasciae connected with the descent of femoral hernia. For
this purpose an incision is to be made from the neighbourhood of the
anterior superior spinous process of the ilium inwards, in the line of the
groin, and carried half way down the inside of the thigh. The large flap
of integument thus marked out is to be raised and turned outwards. The
subcutaneous fascia is then to be laid bare by the removal of any fat, and it
will be advantageous if this can be done in concert with the dissector of the
abdomen (p. 292). Various small superficial arteries and veins will be seen,
viz. : the superficial epigastric, superficial circumflex iliac, and superior and
inferior superficial pudic (p. 437). The fascia lata will be laid bare, and the
cribriform fascia overlying the saphenous opening. On the surface of the
fascia lata will be brought into view the internal or long saphenous vein
passing into the saphenous opening, frequently presenting two branches
(p. 475) ; nearly in front of the femoral artery, the crural branch of the
genito-crural nerve ; and, in front of the anterior superior spine of the ilium,
the external cutaneous nerve (p. 660). A twig of the ilio-inguinal nerve
may also be seen distributed to the skin of a small part of the thigh close to
the pubes. The border of the saphenous opening is to be made distinct by
removing the cribriform fascia, and in doing this the attachment of the
superior cornu or falciform process to the pubic portion of the fascia lata is
to be shown (p. 293). This falciform process is then to be separated from
the fascia lata and turned to the outside sufliciently to expose the infundi-
buliform or crural sheath, investing the femoral vessels, and the dissector
ANTERIOR FEMORAL REGION. 1081
may examine the three compartments into which this sheath is divided, and
which contain respectively the artery, the vein, and a lymphatic gland ; the
latter blocking up the crural aperture between the femoral vein and Gimber-
nat's ligament, through which femoral hernia descends. All the relations of
these parts are to be carefully studied with special reference to the operations
for strangulated femoral hernia (p. 1036).
The incision on the inner side of the thigh is now to be prolonged down-
wards towards the middle line beyond the knee, and the dissection of the
front of the thigh continued. The two middle and the two internal
cutaneous branches of the anterior crural nerve, together with the branch
from the internal saphenous nerve to the integument of the knee, and the
internal saphenous vein, will be dissected out, and the fascia lata in front
of the thigh made clean (p. 664). The fascia is then to be removed, and
the communications of the internal cutaneous, internal saphenous, and
obturator nerves sought in the lower part of the inner aspect of the thigh
(p. 666). Scarpa's triangle is now to be cleaned, and the dissection of the
femoral vessels both in that space and in the after part of their course is to
be studied (p. 434). Towards its termination below the middle of the thigh,
the femoral artery will be observed to be covered by a tendinous expansion,
which conceals it for a part of its course before it pierces the tendon of the
adductor magnus muscle : in the passage so formed, known as Hunter's
canal, the femoral artery, which is accompanied by the internal saphenous
nerve, will be seen to give off the anastomotic branch (p. 293).
The deep femoral artery should be dissected as far as the upper border of
the adductor longus muscle ; and the origins of its first branches are to be
brought into view, viz. : the internal circumflex artery, dividing into
ascending, transverse, and descending branches. One or both of the circum-
flex arteries often arise from the femoral artery immediately above the origin
of the deep femoral (p. 438). The sartorius muscle is to be cleaned, and
likewise the gracilis muscle, and the surface of the other adductors ; the
relations of the inferior tendons of the sartorius, gracilis, and semitendinous
muscles may also be exposed (pp. 273 and 276). The student will then
direct his attention to the outer part of the thigh near the hip. He will
there dissect the fascia lata from the remaining part of the gluteus medius
muscle, and from the tensor vaginse femoris muscle, leaving at first a strip
of the fascia extending down to the knee on the outside of the leg, and he
will afterwards expose the deeper band of the fascia which passes inwards to
the hip-joint from within the upper part of the muscle (pp. 273 and 292).
He will also find the branch of the gluteal nerve to the tensor vaginse
femoris by dissecting between it and the gluteus medius muscle (p. 667).
Let him divide successively the tensor vaginae femoris and the remains of
the gluteus medius and minimus, and dissect the two last muscles down to
their inferior attachments, so as to exhibit the bursse between them and the
trochanter major, and the connection of the gluteus minimus with the cap-
sule of the hip-joint (p. 268). While engaged with this proceeding, he will
be enabled to dissect more particularly the ascending and transverse branches
of the external circumflex artery, and to examine their anastomoses with the
gluteal artery (p. 438). Let him then clean the rectus muscle, trace its
anterior and posterior heads close to their origins, and observe the positions
of the limb in which they are respectively tightened (p. 274). The trunk
of the anterior crural nerve is now to be cleaned, its branches to the
extensor muscles are to be dissected, the internal saphenous nerve laid bare
as far as the knee, and the slender twigs to the pectineus muscle seen
1082 DISSECTION OF THE LOWER LIMBS.
passing behind the femoral vessels. These last may be most easily found if
the common femoral artery be previously divided (p. 664). If the accessory
obturator nerve is present, it will now be seen passing over the brim of the
pelvis to the outer border of the pectineus muscle which it partly supplies
(p. 666). The pectinens and adductor longus muscles are then to be
divided, and their attachments carefully dissected. The continuation of the
profunda femoris artery behind the adductor longus is to be cleaned ; and
its four perforating branches, of which the fourth is the continuation of the
artery, will be seen piercing the adductor magnus muscle (p. 439). When
the pectineus muscle has been reflected, the accessory obturator nerve may
be traced to its communication with the main obturator nerve, to the pec-
tiueus muscle, and to the hip-joint. The anterior division of the obturator
nerve is to be traced down in front of the adductor brevis muscle, and on
division of the pectineus muscle its posterior division to the adductor
magnus will come into view. The obturator nerve will be observed to
supply all the adductor group of muscles (p. 662). The dissector will now
trace the internal circumflex artery ; he will find it dividing into two
branches, one of which passes inwards in front of the obturator extern us and
adductor brevis muscles, while the other is directed backwards to anasto-
mose with the sciatic artery, and gives off a branch to the hip-joint which
enters it by the notch of the acetabulum (p. 439). The obturator externus
muscle is to be cleaned, and the external and internal divisions of the
obturator artery are to be laid bare from, among its fibres (pp. 269
and 423).
The adductor magnus muscle is then to be cleaned and examined (p. 277);
and after it the conjoined insertion of the psoas and iliacus muscles (p. 271);
the vastus externus, vastus internus and crureus muscles, together with the
deep fibres of the latter, called subcrureus, which are inserted into the syno-
vial membrane of the knee-joint (p. 275).
4. Hip-joint — When this stage of the dissection has been reached, the
student may either saw through the femur and leave the hip-joint to a more
convenient opportunity, or dissect the joint at this time, and afterward*
disarticulate the femur. The latter plan is usually to be preferred. In
that case, the attachments of all the muscles which act upon or are related
to the hip-joint are to be reviewed, and those which remain uncut are to be
severed ; the capsular ligament is to be cleaned ; its thinness or deficiency
on the posterior aspect, and the thick accessory or ilio-femoral ligament,
strengthening it in front, are to be noted (p. 151). The relation of the
head of the femur to the acetabulum in the various positions of the limb and
foot are to be observed. The capsule may then be opened, and the cotyloid,
transverse, and round ligaments examined, together with the articular
surfaces and synovial membrane : the limb may then be removed from the
body.
5. The Back of the Leg. — After the separation of the limb from the trunk,
and when the divided structures have been cleaned and cut conv* niently
short, the student will proceed with the dissection of the calf and back of
the leg, by directing an incision down the middle of the limb to the heel,
and reflecting the skin to each side. He will trace the external and internal
saphenous veins as far as the outer and inner ankle (p. 475) ; accompanying
the latter he will find the internal saphenous nerve (p. 666), and along with
the former he will find the external saphenous nerve arising from the union
of the communicans tibialis and communicans fibularis branches of the
internal and external popliteal nerves respectively (p. 677). He will also
THE LEG AND FOOT. 1083
find another cutaneous branch of the external popliteal nerve ramifying on
the outer side of the leg. The gastrocnemius muscle is then to be cleaned,
and the nerves and vessels entering it are to be more particularly dissected
(p. 283). Its thin and flat tendon is then to be carefully divided at its
lower part from that of the soleus, and the muscle is to be turned upwards.
The soleus muscle will thus be brought into view, and, resting upon it the
plantaris (which however is sometimes absent). Between the soleus muscle
and the knee-joint the popliteus muscle will be seen protected by the pop-
liteal aponeurosis, and, crossing it, the lower part of the popliteal vessels
and internal popliteal nerve giving off branches to these muscles (pp. 442
and 676). The popliteus muscle is to be preserved to be dissected more
particularly with the knee-joint. The plantaris and soleus muscles are to be
separated from their superior attachments, and the nature and connexions
of the teiido Achillis examined (p. 285) ; after which the latter may be
divided near its insertion. The deep fascia is then to be divided, and the
flexor longus digitorum, tibialis posticus, and flexor longus pollicis muscles,
lying in this order from within outwards, are to be dissected (pp. 286
and 288). The anterior tibial artery will be seen perforating the inter-
osseous membrane to arrive at the front of the leg, and the posterior tibial
artery, vense comites, and nerve are to be studied, and the branches of the
nerve to the popliteus and other three deep muscles followed ; while the
peroneal artery is to be traced downwards in the fibres of the flexor longus
pollicis muscle, and will be observed to give off the anterior peroneal and a
communicating branch to the posterior tibial artery (pp. 444 and 677).
The relations of the tendons, artery and nerve behind and below the inner
ankle are to be particularly noted.
6. The Sole of the Foot. — The skin is to be reflected by means of an
incision along the middle line of the heel and sole, and a transverse one
across the balls of the toes. The plantar cutaneous branch of the posterior
tibial nerve is to be traced to its distribution ; and, on removing the fat
from the plantar aponeurosis, an outer and inner set of small nerves and
vessels will also be found perforating the latter (p. 296). Below the inner
ankle the internal annular ligament is to be cleaned, and the tibialis
posticus muscle is to be dissected to its insertion (pp. 288 and 295). The
skin is to be divided up the middle of the toes; the sheaths for the flexor
tendons are to be exhibited, and the digital arteries and nerves on both
sides of each of them are to be traced. The plantar aponeurosis is then to
be removed by dissection from the muscles which it covers as much as
possible, so as to expose the abductor pollicis, flexor brevis digitorum, and
abductor minimi digiti muscles (p. 289). The insertions of the tendons
of the flexor brevis digitorum are to be followed by divi-ling the sheaths on
the toes ; its posterior attachment is to be divided, and the branch of the
internal plantar nerve which supplies it sought. This will bring into view
the tendons of the flexor longus digitorum and flexor longus pollicis, the
union of which will be noted ; the flexor accessorius and the lumbricales
muscles will now also be dissected (p. 287). Crossing the flexor accessorius
muscle are the external plantar artery and nerve ; the artery is to be
followed to the deeper part of its course where it forms the plantar arch.
The branches of the nerve to the flexor accessorius and abductor minimi
digiti are to be found, its distribution to the two outer toes is to be traced,
as also the origin of its deep branch (p. 679). The flexor accessorius muscle
is to be removed from its broad origin, and the tendons of the flexor longus
pollicis and flexor longus digitorum are then to be divided. The internal
1084 DISSECTION OF THE LOWEE LIMBS.
plantar artery is to be dissected forwards to the inner side of the great toe ;
and the internal plantar nerve, after giving branches to the abductor
pollicis, flexor brevis pollicis and two inner lumbricales muscles, will be
traced forwards to its distribution on both sides of the three inner toes and
one side of the fourth toe (pp. 446 and 677). The deep branch of the
external plantar nerve is to be traced to its distribution in the two outer
lumbricales, the transversus pedis, adductor pollicis, and all the interossei
muscles, save the outermost two, which, together with the flexor minimi
digiti, are supplied by the external digital branch. The arch of the
external plantar artery will at the same time be traced to the first inter-
osseous space, and its digital and other branches dissected (p. 447). After
these parts have been examined, the attachments of the flexor brevis and
abductor pollicis, transversus pedis, and flexor brevis miuimi digiti muscles
are to be fully studied.
7. The Front of the Leg, and Dorsum of the Foot. — The remaining in-
tegument having been removed from the front of the leg and upper surface
of the foot, the dissector will trace the cutaneous veins and nerves in this
region. On the inner border of the foot will be found the small terminal
twigs of the internal saphenous nerve, and in front of the inner ankle the
commencement of the great saphenous vein. (pp. 475 and 666) ; while on
the foot externally, and passing behind the outer ankle, will be observed
the external or posterior saphenous vein and nerve (pp. 476 and 677). On
the middle of the leg externally, the musculo-cutaneous nerve will be seen
piercing the aponeurosis and becoming superficial, and its distribution is to
be traced to the inner side of the great toe and to the adjacent sides of the
toes in the three outer interdigital spaces (p. 680); while the first inter-
digital space will be found supplied by a branch continued from the anterior
tibial nerve. Immediately above and to the inside of the ankle-joint will
be found the upper transverse and the lower oblique parts of the anterior
annular ligament or retinaculum binding down the tendons of the extensor
muscles (p. 295). These are to be kept, the rest of the aponeurosis being
removed : there will thus be exposed in order from within outwards, the
tibialis anticus, extensor pollicis, extensor longus digitorum, and peroneus
tertius muscles, which are to be dissected to their insertions (p. 279). On
the dorsum of the foot the extensor brevis digitorum is also to be dissected ;
preserving at the same time the anterior tibial vessels and nerves, and the
musculo-cutaneous nerves already mentioned. Arising from the outer
aspect of the fibula, the peroneus longus and brevis muscles are then to be
cleaned (p. 282) : the latter is to be traced to its insertion, but the course
of the tendon of the peroneus longus across the sole of the foot will be more
fully seen when the ligaments are dissected. The musculo-cutaneous nerve
is to be traced upwards to its origin from the external popliteal or peroneal
nerve, and, as it pierces the fibres of the peronei muscles in its course round
the fibula, its branches to these muscles will be seen. The anterior tibial
nerve is then to be traced beneath the muscles and round the fibula, and
downwards on the front of the interosseous membrane, and will be found to
supply in the leg the extensor longus digitorum, tibialis anticus, extensor
pollicis, and peroneus tertius muscles, and on arriving at the foot, the
extensor brevis digitorum (p. 682). The anterior tibial artery will at the
same time be dissected, and its branches traced, viz., its recurrent branch
passing upwards on the tibia through the origin of the tibialis anticus
muscle, to anastomose with the articular branches of the popliteal artery ;
its muscular branches, and its external and internal malleolar branches ;
ARTICULATIONS OF THE LEG AND FOOT. 1085
here there will generally be seen the anastomoses between the external
malleolar and the anterior peroneal arteries (p. 449). The continuation of
the anterior tibial artery as the dorsal artery of the foot is to be traced
forwards to its junction with the plantar arch in the first interosseous space,
and its tarsal and metatarsal branches are to be examined with the branches
supplied by the latter to the three outer interospcoua spaces (p. 450).
Finally, the interossei muscles are to be dissected and examined in their
dorsal and plantar aspects (p. 291).
8. The Knee- Joint , Ankle-Joint, and Articulations of the Foot. — The
tendons passing near the knee-joint are, in the first place, to be cleaned ;
and the anastomoses of blood-vessels upon the knee are to be more particu-
larly examined, viz., the anastomotic branch of the femoral artery, the
external and internal superior articular, and external and internal inferior
articular branches of the popliteal artery, and the recurrent branch of the
anterior tibial artery. The three parts of the insertion of the tendon of the
semimembranosus muscle and the posterior ligament are to be exhibited
(p. 271): the popliteus muscle is then to be dissected out, and its tendon
traced to its origin (p. 285) ; the tendon of the biceps musclo is also to be
dissected to its insertion in connection with the external lateral ligament
(p. 270) ; and at the same time the internal lateral ligament is to be dis-
played (p. 153). In front the ligamentum patellae is to be cleaned, and
the extension upwards of the synovial sac of the knee-joint carefully exa-
mined ; the joint may then be opened by cutting into the synovial sac at
this place, and reflecting the remains of the quadriceps extensor femoris
muscle. Inside will be seen tie ligamentum mucosum, the alar ligaments,
and the fatty processes of the synovial membrane; the extent of the
synovial cavity will be carefully inspected, and with a little dissection the
crucial ligaments may then be brought into view. The capsule of the joint
ought next to be ent:rely removed, in order that the form and actions of
the lateral and crucial ligaments and the movements of the semilunar carti-
lages may be better studied. The structure of the latter will be best seen
after the femur has been separated from the tibia.
The movements of the ankle-joint ought to be studied in connection with
those of the tarsal articulations (p. 158). Its principal ligaments are to be
cleaned externally, viz., the external lateral in three distinct parts, the
internal lateral, and the transverse or posterior. When the internal exami-
nation-of this joint has been completed, the superior and inferior tibio-
fibular articulations and the interosseous membrane are to be studied. On
the dorsnm of the foot the numerous short dorsal ligaments of the tarsal
and metatarsal bones are to be cleaned. On the sole of the foot the super-
ficial and deep parts of the calcaneo-cuboid ligament, the inserted tendons
of the tibialis posticus and peroneus longus muscles, the scaphoido-cuboid,
scaphoid o-cuneiform, and various other shorter ligaments are to be dissected.
The examination of the remaining joints of the foot may then be com-
pleted in the following order : the posterior articulation of the astragalus and
calcaneum, bounded in front by the strong interosseous ligament ; the articu-
lation of the astragalus, calcaneum, and scaphoid, in which the inferior
calcaneo-scaphoid ligament is especially to be observed ; the calcaneo-cuboid
articulation ; the articulation between the cuboid and fourth and fifth meta-
tarsal bones ; the articulation between the scaphoid and cuneiform bones,
which passes forwards between the latter ; the articulation between the two
outer cuneiform bones and the second and third metatarsal bones j and the
articulation between the internal cuneiform and first metatarsal bone.
1086 DISSECTION OF THE LOAVEB, LIMBS.
The mode of connection of the metatarsal bones with each other is to bo
observed ; the interosseous, dorsal and plantar ligaments of their bases,
and the transverse metatarsal ligament of their heads. Lastly, the articu-
lations of the metatarsal bones with the first phalanges, and of the phalanges
with each other are to be dissected. In connection with the great toe, the
arrangement of the sesamoid bones deserves particular attention,
INDEX.
ABDOMEN (abdo, I hide), dissection of,
1069
fasciae of, 257
lining membrane of, 258
muscles of, 248
regions of, 823
viscera of, 824
position of, 826
Abdominal ring, external, 250, 1019
internal, 258, 1023
Abducent (ab, from ; diwo, I lead) nerves,
610
Abduction, 120
Abductor. See MUSCLES
Absorbent glands, clxxxvi. See GLANDS,
LYMPHATIC
system, clxxxii. See LYMPHATIC
SYSTEM
Absorbents, xlviii. See LYMPHATICS
Accelerator. See MUSCLES
Acervulus (dim. of acervus, a heap) cere-
bri, 552
Acetabulum (a vessel for holding vine-
gar), 93, 96
Acinus, ccxxiv
Acoustic (d/coucw, I hear) nerve. See
NERVE
Acromion (anpov, a summit ; oyios, a
shoulder), 76, 89
Adduction, 120
Adductor. See MUSCLES
Adenoid (dSTji/, a gland ; 6tSos, form)
tissue, Ixxix
Adipose (adeps, fat) tissue, Ixv. See
FAT
Adventitia capillaris, clxxix
Afferent lymphatic vessels, clxxxvi
nerves, cxxxii, clxii
Affinity, vital, viii
Agminated (agmen, a troop) glands,
ccxxiv, 846
Air-cells, 899
capillaries of, 902
development of, 904
tubes, 898
Ala pontis Varolii, 517
Ala vespertilionis, 986
Al» of diaphragm, 245
Alae — continued.
nasi, 771
of sphenoid bone, 40
of vomer, 48
Alar (ala, a wing) ligaments, 157
Albinos, pigment wanting in, Ixiv
Albumen, vi
of blood, xxxix
Albuminoid principles, chief characters
of, vi
Alimentary (alimentum, food) canal,
779
Allantois (dAAas, a sausage ; et'Soy, shape),
995
Alveoli (alveolus, a small hollow vessel)
of lower jaw, 5 1
upper jaw, 44
formation of, 792
of lungs, 900
lymphatic glands, clxxxvii
mucous membrane, cc
stomach, 835
Amphiarthrosis (d^t, on both sides ;
apOpov, a joint), 119
Ampullae (ampulla, a flask or bottle) of
labyrinth, 754
membranous, 758
of Fallopian tube, 992
Amygdala? (a/j.vySa\r), an almond), 813
of cerebellum, 554, 577
Amyloid (d/ivAoi/, starch ; fl8os, form)
bodies in pineal gland, 552
Anapophysis (di/o, upwards; apophysis),
22
Anastomosis (ava, through ; <rro/ia, a
mouth) of arteries, clxvii
of veins, clxxiii
Anatomy (ava, apart ; re/woo, I cut) com-
parative, i
demonstrative, I
descriptive, ii, I
general, ii
systematic, ii, I
topographic, I
vegetable, I
Anconeus (ayKwv, the elbow), 212
Aneurism, axillary operation for, 1007
popliteal, operation for, 1015, 1017
1088
INDEX.
Aufractuosities (anfractus, a winding),
S31
Angeiology (ayyeiov, a vessel ; Ao7os,
discourse), 297
Angle, facial, 73
Angular movement, 120
processes of frontal bone, 34
Ankle-joint, bones of, 104, 105
dissection of, 1085
ligaments of, 159
annular, 295
movements of, 160
Annular (annulus, a ring) ligament of
ankle, 295
of arm, 138
of wrist, 144
protuberance. Sec PONS VAROLII
Annulus ovalis (oval ring), 309
Ansa (a loop) hypoglossi, 626, 640
Anspe Vieussenii, 693
Antihelix (avrt, opposite ; helix), 741
fossa of, 741
Antiprostatic (ai/ri, opposite ; prostate)
gland, 963
Antitragus (avn, opposite ; tragus), 741
Antrum (a cavern), Ixxxviii
of Highmore, 46, 64
of pylorus, 831
Anus, muscles of, 262, 263, 859
AORTA (aetpw, I take up or carry), 332
abdominal, 404
branches of, parietal, 416
visceral, 406
anastomoses of visceral and pa-
rietal branches of, 417
dissection of, 1075
arch of, 332
branches of, 336, 338
peculiarities of, 336
bifurcation of, 404
development of, 325
foramen in diaphragm for, 246
orifice of, 313, 315
sinus of, 335
thoracic, 401
dissection of, 1068
valves of, 307
Apoueurosis (euro, from ; vevpov, a string,
a tendon), Ixxiv, 168
of diaphragm, 245
epicranial, 169
of external oblique muscle, 249
infraspinatus muscle, 210
internal oblique muscle, 250
lower limb, 292
lumbar, 540
of transversalis muscle, 253
upper limb, 230
vertebral, 240
Apophysis (airo, from ; <£t/w, I grow),
Ixxxviii
Apparatus ligamentosus, 128
lachrymal, 709
Appendages, auricular, 304, 308, 311, 315
Appendices epiploicse, 830
Appendix cseci, 852
vermiformis, 852
vesicse, 951
Aqueduct (aquceductus, a conduit) of
cochlea, 38, 757
Fallopius, 38
Sylvius, 525, 550
vestibule, 38, 754
Aqueous humour, 737
Arachnoid (apaxvn, a spider, or spider's
web ; etSos, shape) membrane,
5.62, 565
Arbor vitse (from resemblance of the shrub
so called) of cerebellum, 526
uterinus, 984
Arch of aorta, 332. See AORTA
carpal, posterior, 391
of colon, 854
crural or femoral, 1031
deep, 258, 1033
palmar, superficial, 393
deep, 400
plantar, 447
pubic, 97
of a vertebra, 4
zygomatic, 57
Arches, branchial, 64
dental, 780
vascular, in embryo, 325
visceral, 64
Arciform (arcus, a bow ; fortna, shape)
fibres, 517
Arcus dorsalis humeri posticus, 385
superficial is volae, 393
Areola (a little space) of the mamma,
1 002
AREOLAR TISSUE, Ixix
corpuscles of, Ixxiii
development of, Ixxx
structure of, Ixx
Arm, aponeurosis of, 230
arteries of, 381
bones of, 78
dissection of, 1063
fascia of, 229
lymphatics of, 497
muscles of, 212
action of, 228
nerves of, 646—655, 683
veins of, 465
ARTERIA anastomotica magna, 440
centralis retinse, 729
collaterals magna, 383
ulnaris prima, 384
secunda, 385
comes nervi ischiadici, 429
comes nervi phrenici, 374
dorsalis pedis, 450
dorsalis scapulae, 380
hypogastrica, 420
maxillaris externa, 349
pancreatica magna, 409
pelvica, 420
princeps pollicis, 399
profunda femoris, 437
INDEX.
1089
that by
ed ; ori-
ARTERY — continued.
profunda penis, 428, 958
thoracica humeraria, 379
suprema, 379
thyroidea iraa, 337, 340
ARTERIES (aprripia, from apTrj
which anything is susp
ginally applied to the windpipe,
by which the lungs might be said
to be suspended, rpaxeia aprripia,
artcria aspera, afterwards to the
arteries, at one time supposed,
like the windpipe, to contain air.
Another less probable derivation
is from ayp, air ; rrjpeco, I keep),
General Anatomy of, clxvii
anastomoses of, clxvii
coats, clxviii
contractility of, clxxi
distribution of, clxvii
epithelium of, clxix
muscular tissue of, clxx
nerves of, clxxi
physical properties of, clxviii
rete mirabile of, clxviii
sheath of, clxviii
structure of, clxviii
terminations of, clxxx
tortuosity of, clxviii
vessels of, clxxi
vital properties of, clxxi
ARTERIES, Descriptive Anatomy of, 297
ARTERIES or ARTERY, aberrant, in arm,
385> 387
accessory pudic, 428
of acoustic nerve, 370
acromial thoracic, 379
alveolar, 356
anastomotic, of arm, 385, 388
of thigh, 440
angular, of face, 350
articular, of hip, 439
of knee, 442
auditory, internal, 767
auricular, anterior, 354, 743
posterior, 353, 743
axillary, 377
dissection of, 1062
peculiarities of, 381
basilar, 363, 370
brachial, 381
dissection of, 1064
peculiarities of, 385
surgical anatomy of, 1010
brachio-cephalic, 336, 340
peculiarities of, 337, 340
bronchial, 402, 903
buccal, 356
of bulb, 427
relation of to lithotomy, 1046
capsular, 413
of eye, 733
of liver, 873
cardiac, 338
carotid, common, 336, 341
ARTERY — continued.
carotid, common, development of, 327
dissection of, 1053
peculiarities of, 337, 345
surgical anatomy of, 1005
external, 345
peculiarities of, 346
internal, 359
peculiarities of, 360
carpal, anterior radial, 397
ulnar, 391
posterior radial, 398
ulnar, 391
central, of retina, 360, 729, 739
cerebellar, anterior inferior, 370
posterior inferior, 369
superior, 370
cerebral, anterior, 363
middle, 363
posterior, 370
cervical, ascending, 371
deep, 376
of occipital, 351
superficial, 373
transverse, 366, 373
choroid, 363
posterior, 370
of eye, 721
ciliary, 360, 721, 723
circumflex, of arm, anterior, 381
posterior, 380
iliac, 433
superficial, 437
of thigh, external, 438
internal, 439
clavicular, 379
of clitoris, 428
coccygeal, 429
cochlea, 767
cceliac, 406, 837
colic, left, 412
middle, 410
right, 410
communicating, of brain, anterior, 363
posterior, 363, 370
of palm, 393
coronary of heart, 321, 338
peculiarities of, 340
left, 339
right, 339
of lips, 350
of stomach, 407
of corpus cavernosum, 428, 958
cranial, 351
cremasteric, 433
crico-thyroid, 348
cystic, 408
deferent, 421
dental, 356
digital, of foot, 448, 451
of hand, 393
dorsal, of foot, 450
of fore-finger, 398
of great toe, 451
of lumbar, 417
4 B
1090
INDEX.
ARTERY — continued.
dorsal, of penis, 428
of scapula, 380
of thumb, 398
of tongue, 348
emulgent, 414
epigastric, 432
peculiarities of, 434
relation to femoral hernia, 1034
to inguinal hernia, 1023,
1025, 1030
superficial, 437
superior, 375
ethmoidal, 362
facial, 349
femoral, 434
dissection of, 1080
peculiarities of, 441
relation to femoral hernia, 1033
surgical anatomy of, 1015
deep, 437
dissection of, 1080
frontal, 362
gastric, short, 409
gastro-duodenal, 408
gastro-epiploic, left, 410
right, 408
gluteal, 429
hsemorrhoidal, external or inferior,
426, 858
middle, 421, 858
superior, 412, 858
of hand, peculiarities in, 400
helicine, 958
hepatic, 408, 867, 873
humeral, of acromio -thoracic, 379
transverse, 371
hyoid (lingual), 348
(thyroid), 346
hypogastric, 328, 420
ileo-colic, 410
iliac, common, 418
surgical anatomy of, 1012
external, 431
peculiarities of, 434
surgical anatomy of, 1014
internal, 420
in foetus, 420
surgical anatomy of, 1014
ilio-lumbar, 429
of index finger, radial, 399
infra-orbital, 357
iufraspinous, 373
innominate, 336, 346
peculiarities of, 337, 340
intercostal, aortic, 402
anterior, 374
superior, 366, 376
interlobular, of liver, 873
interosseous, of arm, 390
anterior, 390
posterior, 391
of foot, 450
of hand, dorsal, 391, 399
palmar, 400
ARTERY — continued.
labial, inferior, 350
lachrymal, 357, 360
laryngeal, of inferior thyroid, 371
of superior thyroid, 348
lingual, 348, 812
lumbar, 417
malar, 360
malleolar, external, 450
internal, 449
mammary, external, 379
internal, 366, 374
masseteric, 356
mastoid, 351
maxillary, internal, 354
dissection of, 1055
peculiarities of, 357
superior, 356
median, 391
peculiarities of, 393
anterior, 369
mediastinal, 374
posterior, 402
meningeal, middle and great, 356,
357
of occipital, 351
posterior, 369
small, 356
mesenteric, inferior, 412
superior, 410, 849
metacarpal, 398
of little linger, 391
metatarsal, 450
musculo-phrenic, 375
mylo-hyoid, 356
nasal, of internal maxillary, 357
lateral, 350
of ophthalmic, 362
of septum, 357
nutrient, of femur, 439
of fibula, 445
hip, 429
humerus, 385
radius, 391
tibia, 444
ulna, 391
obturator, 423
peculiarities of, 424
relation to femoral hernia, 1036
occipital, 351
cesophageal, 402
of coronary artery, 407
of inferior thyroid, 371
ophthalmic, 360
ovarian, 414, 416, 987, 992
palatine, inferior or ascending, 349
superior or descending, 357
of pharyngeal, 358
palmar, superficial, 393
deep, 400
palpebral, 362
pancreatic, 409
pancreatico-duodenal, 408
inferior, 410
perforating, of foot, 448
INDEX.
1091
ARTERY— continued.
perforating, of hand, 400
of thigh, 439
of thorax, 374
pericardiac, 374, 402
perinea], superficial, 426
in females, 428
transverse, 427
peroneal, 444
anterior, 445
petrosal, 752
pharyngeal, ascending, 357
phrenic, inferior, 416
superior, 374
plantar, external, 447
internal, 446
popliteal, 441
dissection of, 1080, 1083
profunda, of arm, inferior, 384
superior, 383
of penis, 428
of thigh, 437
pterygoid, 356
ptery go-palatine, 357
pubic, 434
of obturator, 424
pudic, 425
accessory, 428
external, 437
in female, 428
pulmonary, 331, 898, 902, 903
from abdominal aorta, 406
development of, 326
in foetus, 328
valves of, 307
pyloric, 408
radial, 394
dissection of, 1065
peculiarities of, 385, 386, 399
of index finger, 399
ranine, 349
recurrent, of deep palmar arch, 400
interosseous posterior, 391
radial, 397
tibial, 449
ulnar, 389
renal, 414, 935
sacral, middle, 418
lateral, 430
scapular, posterior, 367, 373
sciatic, 429
sigrnoid, 512
spermatic, 414, 975
spheno-palatine, 357
spinal, anterior, 369
of intercostal s, 404
of inferior thyroid, 371
of lumbar, 417
posterior, 369
of vertebral, 368
splenic, 408, 886
sternal, 374
sterno-mastoid, 351
stylo-mastoid, 353, 752, 768
subclavian, 364
ARTERY— continued.
subclavian, development of, 327
dissection of, 1053
peculiarities of, 337, 367
surgical anatomy of, 1007
sublingual, 348, 349, 818
of submaxillary gland, 817
submental, 350, 351, 818
subscapular, 379
of suprascapular, 373
supra-acromial, 373
supra-orbital, 360
suprarenal, 413
suprascapular, 366, 371
sural, 442
tarsal, 450
temporal, 353
anterior, 354
deep, 356
middle, 354
posterior, 354
thoracic, acromial, 379
alar, 379
external, 379
long, 379
superior, 379
of thumb, dorsal, 398
large, 399
thymic, 374
thyroid, inferior, 366, 371, 919,
922
lowest, 340, 922
superior, 346, 919, 922
tibial, anterior, 448
dissection of, 1083, 1084
peculiarities of, 451
Posterior, 444
issection of, 1083
peculiarities of, 445
tonsillar, 350, 351, 814
tracheal, 371
transverse, of basilar, 370
cervical, 373
efface, 354
humeral or scapular, 371
of perinseum, 427
tympanic, 356, 752
ulnar, 388
dissection of, 1065
peculiarities of, 385, 386, 391
umbilical, 328, 421
uterine, 422, 987
vaginal, 422
of liver, 873
of vas deferens, 421
vertebral, 366, 367
development of, 327
peculiarities of, 369
vesical, inferior, 421
superior, 421
vesico-prostatic, 421
vestibular, 767
Vidian, 357
volar, superficial, 397
Arthrodia (apQpov, a joint), 120
4 B 2
1092
INDEX.
Artlirology (apOpov, a joint ; Ao7oy, a dis-
course), 118
Articular (articulus, diminutive of artus,
a joint) arteries. See ARTERY
ARTICULATION (articulus, a joint), 118
acromio-clavicular, 134, 1064
of ankle-joint, 159, 1085
astragalo-calcaneal, 160
scaphoid, 161
of atlas and axis, 125
ealcaueo-cuboid, 162
scaphoid, 161
carpal, 142, 1066
carpo-metacarpal, 144
classification of, 119
coccygeal, 147
costo-clavicular, 134
costo-sternal, 130
costo-vertebral, 128, 1069
costo-transverse, 129, 1069
crico-arytenoid, 910
crico-thyroid, 909
of elbow, 140, 1066
epiglottis, 908
foot, 1 60, 1085
forearm, 138
hand, 142, 1066
hip, 151, 1082
knee, 153, 1085
larynx, 909
leg, 15?
lower limb, 151
metacarpal, 144
metacarpo-phalangeal, 145
metatarsal, 165
metatarso-phalangeal, 166
modes of, 118
movements of, 120
of pelvis, 147, 1078
peroneo-tibial, 158
pubic, 149, 1078
radio-carpal, 142
ulnar, superior, 138, 1066
inferior, 139, 1066
of ribs, 128, 1069
sacro-coccygean, 1078
sacro-iliac, 147, 1078
sacro-vertebral, 147, 1078
scapulo-clavicular, 134, 1064
scapulo-humeral, 136
sterno-clavicular, 134
tarsal, 161
tarso-metatarsal, 164
temporo-maxillary, 132
thyro-hyoid, 909
of tympanic bones, 749
upper limb, 134, 1064, 1066
vertebral column, 121, 1059, 1069
Arytenoid (apvraiva, a pitcher or ladle ;
ei'Sos, shape) cartilages of the
larynx, 907
ligaments, 909
muscles, 917
Asternal (a, ueg. ; viepvov, the breast)
ribs, 24
Astragalus (aa-rpayaXos, the ankle-bone,
or a dice, the astragali of the
sheep having been used as dice by
the ancients), 107
Atlas (o euphonic; rA^t, I bear), 8
ligaments of, 125
loop of the, 636
ossification of, 19
Atrium (a court before a house) of auri-
cles of heart, 304
Attollens (attollo, I raise up). See
MUSCLES
Attrahens (ad, to ; traho, I draw). See
MUSCLES
Auditory artery, 767
canal, external, 743
meatus, external, 37, 61, 743
internal, 38
nerve, 587, 589, 615
arrangement of membranes of,
cxlix
cochloar division, 763
vestibular division, 758
process, 37
Auricle (auricula, the outer ear) of ear,
740
ligaments of, 742
muscles of, 742
nerves of, 743
vessels of, 743
Auricles of heart, 304. See HEART
Auricular arteries, 353, 354, 753
muscles, 170, 742
nerves. See NERVES
surface of sacrum, n, 95
Auriculo-temporal nerve, 606
Amiculo-ventricular furrow, 303
orifices, 308, 312
size of, 322
rings, 316
valves, 305
Axial fibre of nerve. See Axis, Cylinder
Axilla, dissection of, 1061
position of parts in, 377
Axis (vertebra), 9
development of, 19
ligaments of, 125
cerebro-spinal, cxxxii, 501
cceliac, 406
cylinder of nerve-fibre, cxxxvi
of pelvis, 99
thoracic, 381
thyroid, 371
Azotised (azote, nitrogen) substances, v
Azygos (a£vyos, unyoked) artery, 443
veins, 469, 471
uvulae muscle, 190
BACK, dissection of, 1060
muscles of, 232
Band, furrowed, 525
primitive, of nerve-fibre, cxxxvi
Bands of Goll, 510
INDEX.
1093
Bartholin's glands, 978
Base, molecular, of chyle, xlix
Basement membrane of glands, ccxxiv
of mucous membrane, cxcvii
of skin, cciii
of teeth, 797
Basilar (basis, a base) artery, 370
bone, 29
process of occipital bone, 3 1
Basilic vein (f}avi\iKos, royal ; this vein
having been supposed by the
old physicians to be connected
•with the liver and spleen, which
they termed the basilic viscera),
466
Basio-glossus (Pavis, a base ; y\(i><T<ra, a
tongue) muscle, 186
Bauhin, valve of, 852
Bellini, ducts of, 930
Bertin, bones of, 40
Biceps (bis, twice ; caput, a head) muscles,
212, 270
Bichat, canal of, 548
Bicuspid (bis, twice ; cuspis, the point of
a weapon) teeth, 782
valve, 313
Bile, 879
Bile-duct, common, 868
ducts, aberrant, 877
origin of, 875
structure of, 877
Bipolar nerve-cells, cxl
Biventer (bis, twice ; venter, a belly)
muscle, 237
Biventral lobe of cerebellum, 524
Bladder, gall. See GALL-BLADDER
BLADDER, urinary, 944
capacity of, 945
coats of, 948, 951
detrusor muscle of, 949
development of, 995
female, peculiarities of, 947
ligaments of, false, 945, 947
true, 260, 261, 945, 952
neck, or cervix of, 945, 947
openings of ureters into, 948
position of, 825, 944, 945, 1041
puncture of, 1042
sacculated and fasciculated, 951
sphincter muscle of, 949
structure of, 948
trigone of, 948
urethral orifice of, 948
uvula of, 948
vessels and nerves of, 951
Blastema (pxaa-ravca, I germinate), xix
Blastoderm (/8AatrTcwa>, I bud, or germi-
nate ; Sep/xo, a skin), 15
BLOOD, xxvii
arterial and venous, xlii
chemical composition of, xxxiii, xli
circulation of, clxvi
in foetus, 328
coagulation of, xliv
colouring principles of, xxxiv
BLOOD— continued.
corpuscles, pale, xxxi
red, xxviii
differences of, in animals, xxviii
formation of, 1
composition of, xxxiii
structure of, xxix
crystals of, xxxv
hepatic, xliii
liquor of, xxxvii
occasional constituents of, xxxii
physical properties of, xxvii
plasma of, xxxii
portal, xliii
renal, xliv
splenic, xliii
tables of composition of, xlii
BLOOD-VESSELS, General Anatomy of,
cxlv
development of, clxxx
See ARTERIES, VEINS, CAPILLA-
RIES, also under the several organs
and tissues, for blood-vessels belong-
ing to them
Bluinenbach's norma verticalis, 73
BONE, General Anatomy of, Ixxxvii
cavities of, Ixxxviii
chemical composition of, Ixxxix
classes of, Ixxxvii
compact or cancellated, xc
corpuscles of, xliv
eminences of, xxxviii
external configuration of, Ixxxvii
formation and growth of, cii
Haversian canals, xci
spaces, xciii
lacunae of, xciv
lamellae of, xc, xcii, xcv
fibres of, xcv
lymphatics of, cii
madder, influence of, on, cxiii
marrow of, c
nerves of, cii
perforating fibres of, xcvi
periosteum of, c
physical properties of, Ixxxviii
processes of, Ixxxviii
structure of, xc
vessels of, ci
BONES, Descriptive Anatomy of, 2
of ankle, 107
astragalus, 107
atlas, 8
axis, 9
of Bertin, 40
calcaneum, or os calcis, 107
carpal, 83, 90
clavicle, 77, 89
coccyx, 12
cuboid, 108
cuneiform, of carpus, 84
tarsus, 109
of ear, 748
ethmoid, 42, 69
femur, ioo; in
1094
INDEX.
BONES — continued.
fibula, 105, in
of fingers, 87
of foot, 106
frontal, 33, 67
of hand, 83
humerus, 78, 90
hyoid, 52, 70
iliurn, 94, no
incus, 748
innominate, 93, no
ischium, 96, no
lachrymal, 50, 70
lenticular, 749
lingual, 52
of lower limb, 100
lunate, 84
magnum, 85
malar, 49, 70
malleus, 748
maxillary, superior, 44, 69
inferior, 51, 70
metacarpal, 86
metatarsal, 109, ill
nasal, 49, 7°
navicular, of carpus, 84
tarsus, 1 08
number of, 2
occipital, 29, 67
orbicular, 749
palate, 46
parietal, 32, 67
patella, 103
pelvic, 93, in
phalangeal, of hand, 87, 90
foot, no, in
pisiform, 85
pubic, 95, 1 10
pyramidal, 84
radius, 80, 90
ribs, 24
peculiarities of some, 26
sacrum, 11
scaphoid, of carpus, 84
tarsus, 1 08
scapula, 74, 89
semilunar, 84
sesamoid, in hand, 88
in foot, 1 10
of skull, 29
spongy, ethmoidal, 43, 63
inferior, 50, 63, 70
middle, 43
sphenoid, 38, 68
sphenoidal, 40, 69
stapes, 749
sternum, 23
tarsal, 106
temporal, 35
tibia, 103
trapezium, 85
trapezoid, 85
triquetral, 55
turbinate, superior, 43
inferior, 50
BONES — continued.
ulna, 8 1
of upper limb, 74
unciform, 86
ungual, 50
vertebra dentata, 9
prominens, 8
ebr
vertebra?, 3
vomer, 48
Wormian, 55
Bourrelet (a cushion or pad), 542
Brachia (arms), in cerebrum, 552, 557
Brachial artery, 381. See ARTERY
Brachio-cephalic (brachium, the arm ;
/ce<J>oA7j, the head) artery, 336
Brachy cephalic (Ppaxvs, short ; Ke^aA??,
the head) skulls, 73
BRAIN, 513, 529. See CEREBRUM and
ENCEPHALON
dissection of, 1049
vessels of, 567
Branchial (fipayx'a, gills) arches, 64
clefts, 64
Breast. See MAMMARY GLAND
Bronchi (&poyx°s, the windpipe), 889
position of, at root of lungs, 898
vessels and nerves of, 892
Bronchia (Ppoyxos, the windpipe), 898
development of, 904
Bruch, membrane of, 717
Brunner's glands, 849
Bubonocele (/3ot/#a>i/, the groin ; KTJAT;, a
tumour), 1025
Buccal (biicca, the mouth) artery, 356
nerve, 606
Buccinator (Jbuccina, a trumpet), muscle,
176
Buff'y coat of blood, xxxiii
Bulb, olfactory, 584
of urethra, 958
artery of, 427, 1046
Bulbi vestibuli, 975
Bulbo-cavernosus muscle, 264
Bulbs of corpora cavernosa, 956
of fornix, 537
Bulbus arteriosus, 323, 325
Bursa (a pouch), cxciv
Bursse, synovial, or bursae mucosse,
cxciv
CADAVERIC rigidity, cxxxi
Cseeum (i.e., intcstinum caecum, the blind
gut), 852
development of, 86 1
Calamus scriptorius (a writing pen),
51?
Calcaneo-cuboid articulation, 162
Calcaneo-fibular ligament, 160
Calcaneo-scaphoid ligaments, 161
Calcaneo-talar (calcaneum; talus, the
astragalus) ligament, 160
Calcaneum (belonging to the heel, from
calx, the heel), 107
Calcar avis (a bird's spur), 544
INDEX.
109-5
Calcarine fissure, 536
Calcification of teeth, 797
Calyces (/roAv£, a cup) of kidney, 928
Calvarium or Calvaria (the roof of the
skull ; calvus, bare), removal of,
1049
Camper's facial angle, 73
Canal, alimentary, 779
abdominal portion, 823
development of, 859
auditory, external, 743
internal, 38
of Bichat, 549
carotid, 37, 59
central of modiolus, 756
crural, 293, 1034
dental, 52
facial, 38
femoral, 293, 1034
of Huguier, 745
Hunter's, 294
incisor, 63
infra-orbital, 57
inguinal, 963, 1023
lachrymal, 46, 709
of Nuck, 965, 987
palatine, anterior, 45
posterior, 47, 58
of Petit, 736
pterygoid, 42
ptery go-palatine, 41, 58
sacral, 12
of Schlemin, 721
of spinal cord, 508
spiral, of cochlea, 755
vertebral, 5
membranes in, 563, 564, 565
Vidian, 42, 57
of Wirsung, 882
Canaliculi in bone, xciv
lachrymal, 709
Canalis centralis modioli, 756
membranacea of cochlea, 761
reunions of cochlea, 761
spiralis modioli, 756, 763
Canals of Gartner, 998
of Havers, xci
portal, 873
perivascular, cxxxvii
semicircular, of ear, 754
membranous, 758
Cancelli (lattice-work) of bone, xc
Canine fossa, 45
teeth, 781
development of, 800, 803
Can thus (KavQos, the corner of the eye),
705
Capacity of auricles and ventricles,
322
vital, of lungs, 896
CAPILLARY (capillus, a hair) vessels,
General Anatomy of, clxv, clxxv
development of, clxxx
discovery of, clxxv
network of, clxxv
CAPI LLARY vessels — continued.
network of, peculiarities of, clxxvi
structure of, clxxvi
vital properties of, clxxix
Capitellum (dim. of caput, a head),
Ixxxviii
of humerus, 79
Capitulum (dim. of caput, a head),
Ixxxviii
of rib, 25
Capsulae atrabiliarire, 939
Capsular artery. See ARTERY
ligament. See LIGAMENT
Capsule, Glisson's, 857, 870
of lens, 733
Capsules, suprarenal, 939
synovial, cxciii
Caput (a head) of bone, Ixxxviii
Caput caecum coli, 825, 852
galliuagiuis (woodcock's head)
961
Cardiac («a/>8ta, the heart) artery, 338
nerves. See NERVES
orifice of stomach, 831
Cardinal veins, 484
Carotid (/ca/jam5es apT-qpiai, soporific arte-
ries, from Kapow, I cause sleep :
also said to be from xapa, the head ;
ous, the ear) artery. See ARTEKY,
Carotid
canal, 37, 59
foramen, 37
plexus, 6^9
Carpal (Kapiros, the wrist) arteries. See
ARTERY
ligament. See LIGAMENT
Carpo-mttacarpal articulation, 144
Carpus (Kapiros, the wrist), articulations
of, 142
bones of, 83
ligaments of, 144, 231
ossification of, 90, 93
compared with tarsus, 115
CARTILAGE (cartilago, gristle), General
Anatomy of, Ixxx
articular, Ixxxii
chemical composition of, Ixxxiv
cricoid, 906
of ear, 741, 744
ensiform, 23
of epiglottis, 908
fibro-, Ixxxvi
interarticular, Ixxxvi
hyaline, Ixxxi
development of, Ixxxv
of ribs, Ixxxiii
Meckel's, 66, 769
of primordial cranium, 65
of septum of nose, 772
temporary, Ixxxi
thyroid, 906
varieties of, Ixxxi
xiphoid, 23
yellow, Ixxxv
CARTILAGES, arytenoid, 907
1096
INDEX.
CARTILAGES— continued.
of bronchi, 892
of bronchia, 899
costal, 26
connection of ribs with, 130
cuneiform, 908
of larynx, 905
ossification of, 920
structure of, 908
of nose, 771, 772
of ribs, 26
semilunar, of knee, 155
tarsal, of eyelids, 706
of Santorini, 908
of trachea, 890
of Wrisberg, 908
Cartilagines alarum nasi, 772
laterales nasi, 771
minores nasi, 772
sesamoidese, 772
Cartilago triticea (wheat-shaped carti-
lage), 909
Caruncula (dim. from caro, flesh) lachry-
inalis, 705
Carunculse myrtiformes, 978
Casein (caseus, cheese), v
Cauda equina (horse's tail), 503, 631
development of, 574
Cavernous nerves of penis, 703
plexus, 689, 690
sinus, 463
tissue, clxxx
Cavities of bones, Ixxxviii
of reserve (teeth), 801
posterior, 802
sigmoid, of ulna, 82
Cavity, abdominal, 823
buccal, 779
cotyloid, 96
cranial, 60
cranio - vertebral, development of,
glenoid, 76
neural, 3
pulp, of tooth, 785
semilunar of radius, 81
visceral, 3
CELLS, anastomosing, of cornea, 715
animal, xii
changes in, xi, xxi
ciliated, of organ of Corti, 767
contents of, xiii
of Deiters, 767
endogenous formation of, xvii
epithelial, lii, Ivi, Iviii
ethmoidal, 43
fat, Ixv, Ixvi
fissiparous multiplication of, xv,
xvii
function of, in nutrition, xxv
furrowed and spinous of epithelium,
Iv
of grey matter of cerebellum.
528
hepatic, 873
CELLS — continued.
mastoid, 746
motion of protoplasm in, xix
of nerve-substance, cxxxix, cxlii,
clxiv
nuclei of, xiii
multiplication of, xviii
olfactory, civ, 776
pigment, Ixiii
of eye, 718, 719
production of, xv, xix
by division, xvii
in ovum, xv
in relation to formation of textures,
xxi, xxiii
secreting, ccxx
spermatic, 976
structure of, xiii
vegetable, x
Cellular tissue, Ixix. Sec AREOLAR
TISSUE
Cellulose, xiii
Cement of teeth, 785, 791
development of, 799
Centra of embryonic vertebrae, 21
Centre, phrenic, 245
Centrum geminum semicirculare, 55°
ovale of Vieussens, 541
ovale minus, 541
of vertebrae, 22
Cephalic (/cc^aATj, the head) vein, so
called from having been supposed
by the old physicians to be con-
nected with the head, 466
Cephalogenesis (/ce^oArj, the head; yevevis,
production), 72
Cerato-glossus (/cepas, a horn ; y\<a<rcra, a
tongue) muscle, 186
CEREBELLUM (dim. of cerebrum, the
brain), 522
corpus dentatum of, 526
crura of, 522, 527
development of, 575, 577
dissection of, 1051
falxof, 564
fissures of, 522, 523
hemispheres of, 522
internal structure of, 526
lobes of, 524
microscopic structure of, 529
peduncles of, 522, 527, 557
tentorium of, 563
veins of, 460
ventricle of, 525
vermiform process of, 522
weight of, 571
CEREBRO-SPINAL axis or centre, 501
blood-vessels of, 567
development of, 573
General Anatomy of, cxxxii
internal structure of, 518, 526,
554
membranes of, 562
fluid, 566
nerves, cxliv, 582. Sec NEKVES
INDEX.
1097
CEREBRUM (the brain). 529
anfractuosities of, 531
base of, 536
convolutions of, 531
Foville's classification of, 534
Gratiolet's, 535
Leuret's, 535
commissures of, 550, 557
crura of, 536, 556
development of, 575
dissection of, 1049
exterior of, 529
fibres of, 556
ascending or peduncular, 555
transverse or commissural, 557
longitudinal or collateral, 557
Foville's views on, 558
fissures of, 530, 533, 547
grey matter of, 554, 559
gyri of, 531
hemispheres of, 529
internal parts of, 540
internal structure of, 554
lobes of, 529
peduncles of, 536, 566
sulci of, 531
veins of, 460
ventricles of, 543, 550
weight of, 571
Cerumen (cera, wax), 744
Cervical (cervix, a neck) arteries. See
ARTERY
fascia, 196
nerves, 633, 636
plexus, 636
Cervico-facial division of facial nerve, 613
Cervix, or neck, of bladder, 947
uteri, 983
Chambers of eye, 737
Check ligaments, 126
Cheeks, 55, 779
CHEMICAL COMPOSITION of the different
solids and fluids. See under the
several titles of these .
Chest, muscles of, 240
position of parts of heart in, 313
Chiasma (xia&, I mark with the letter
X ; crossing or decussation), 584
Choledochus (x°^, bile ; Sexo/icu, I re-
ceive) duct, 868
Cholepyrrhiue (x°^?> bile ; wppos, red),
879
Cholesterine (x°^> bile ; o-reop, fat), 879
in blood, xl
in nerve-tissue, cxxxii
Cholic (X^ATJ, bile) acid, 879
Choloidic (xo^rj, bile ; et'Sos, form) acid,
879
Chondrin (xov^pos, cartilage), v, Ixxxiv
Chondro - glossus (xovSpos, cartilage ;
yXcaaaa, the tongue) muscle, 186
Chorda dorsalis, 16, 65
tympani, 611, 753
Chordae tendinese, 305
left ventricle, 313
Chords tendinese, right ventricle, 310
Willisii, 462
Chords, vocal, 910, 912
Choroid (xopiov, the chorion or inves-
ting membrane of the foetus ;
etSoy, shape) plexuses, 548
development of, 581
of fourth ventricle, 526
of lateral ventricles, 543
tunic of eye, 716
pigment cells of, Ixiv
structure of, 717
Chyle (xv^os, juice), xlviii
constitution of, xlix
globules, formation of, 1
Chyliferous (chylus, chyle ; fero, I carry)
vessels, 491
Cilia (cilium, an eyelash), eyelashes, 707
vibratile, lix
Ciliary (cilium, an eyelash) arteries,
360, 721, 723
muscle, 721
nerves, 599, 600, 724, 725
part of retina, 730
processes, 717
vessels of, 722
motion, lix, Ixi
cause of, Ixii
Ciliated epithelium, liii, Iviii
Cineritious (cinis, ashes) substance of
nervous system, cxxxiii
Circle of Willis, 363
Circulation of blood, clxv
foetal, 328
organs of, clxv, 297
pulmonary, clxvi, 297
systemic, clxvi, 297
Circulus articuli vasculosus, Ixxxiv
major, 723
minor, 723
tonsillaris, 618
venosus of nipple, 1004
of retina, 729
Circumduction (circum, about ; diico, I
lead), 120
Circumferential fibro-cartilage, Ixxxvi
Circumflexus (circum, around ; flecto, I
bend). See ARTERY, MUSCLE,
and NERVE.
Claustrum (that which shuts off), 561
Clavicle (clavicula, dim, of clavis, a key),
77
ligaments of, 134
ossification of, 89, 90
Cleft, branchial, 64
Cleido-mastoid («Aety, a key, or the cla-
vicle ; mastoid process) muscle, 193
Clinoid («AIVTJ, a bed ; et'Sos, shape) pro-
< cesses, 39, 42
Clitoris (/fAerropts, perhaps from K\(IW, I
enclose), 977
development of, 1001
erector muscles of, 266, 977
nerves of, 979
vessels of, 978
1098
INDEX.
Cloacal (cloaca, a sewer) aperture, 1001
Coagulation (coagulum, a clot) of blood,
xxvi, xliv
circumstances affecting, xlv
theory of, xlvi
Coccygeal (coccyx) artery, 429
gland, 697
ligament, 147
nerves. See NERVE
Coccygeus (coccyx) muscle, 263
Coccyx (KOKKV£, a cuckoo), 12
ligaments of, 147
ossification of, 20, 21
Cochlea (/coxAoy, a shell-fish with a spiral
shell), 755
aqueduct of, 38, 757
central column of, 755, 756
development of, 769
membranous structure of, 760
nerves of, 763
scalse of, 757
spiral canal of, 755
vessels of, 767
Cochleariform (cochleare, a spoon ; forma,
shape) process, 58
Cceliac (i<oi\ia, the abdomen) artery or
axis, 406, 837
Coins articulaires of Corti, 765
Colic (KCI)\OV, the colon or large intestine)
arteries, 410, 412
Collar-bone, 77
Colles, fascia of, 259
Colliculus bulbi urethra, 959
nervi optici, 726
Colloid (Ko\\a, glue ; etSos, shape) sub-
stances, Graham's researches on,
vi
Colon (K(I)\OV, originally limb), 853
arch of, 854
development of, 86 1
position of, 825
sigmoid flexure of, 854
Colour of arterial and venous blood, xlii
of lungs, 897
Colouring principles in blood, xxxiv
Columella cochleae, 756
Column, posterior vesicular, 510
vertebral, 3
curves of, 13
development of, 15
form of, 14
ligaments of, 121
movements of, 125
Columnse Bertini, 929
carnae (fleshy columns), 305, 310,
312
recti, 858
rugarum, 981
Columnar epithelium, liii, Ivi
layer of retiua, 727
Columns of external abdominal ring,
1019
of rectum, 858
of spinal cord, 506
course of fibres in, 518
Columns of vagina, 987
Comes (a companion ; pi. comites),
clxxiii
nervi ischiadici, 429
nervi phrenici, 374
Commissure (con, together ; mitto, I
send) cerebral, anterior, 550,
557
great, 54 1, 557
middle or soft, 550, 580
_ posterior, 550, 557, 580
optic, 584
of spinal cord, 507
of vulva, 977
Compact tissue of bone, xc
Complex bones, Ixxxviii
Complexus muscle, 237
Compressor (con, together ; premo, I
press). See MUSCLKS
Conarium (conus, the fruit of the lir),
552
Concha («o7%rj, a shell), 74°
Condyle (itot>8v\os, a knuckle), Ixxxviii
Condyles of femur, 102
of humerus, 79
of lower jaw, 52
of occipital bone, 31, 59
Condyloid portions of occipital bone, 29,
31
surfaces of tibia, 103
Cone, fibrous, 556
Cones of retina, 727
Congenital hernia, 1025
Conglobate (con, together ; globus, a
ball) glands, clxxxvi
Conglomerate (con, together ; glomcro, I
gather in a round heap) glands,
ccxxiv
Coni vasculosi, 970
Conjunctiva (con, together ;jungo, I join),
708
Connecting fibro-cartilage, Ixxxvi
Connective tissue, Ixix
corpuscles of, Ixxiii, clxxix
development of, Ixxx
homogeneous, Ixxix
jelly-like, Ixxviii
retiform, Ixxix
in nerve-substance, cxli
special varieties of, Ixxviii
Conoid (KOVOS, a cone ; flSos, shape) liga-
ment, 135
Constrictor (con, together ; stringo, I
draw tight). See MUSCLES
Contour lines of dentine, 788
of muscle, cxxxvi
Contractility of arteries, clxxi
of lymphatics, clxxxv
muscular, cxxix
of skin, ccxviii
of veins, clxxiv
vital, viii
Conus arteriosus, 310
Convolutions (con, together ; volvo, I
roll) of brain, 531
IXDEX.
1099
Convolutions, cerebral, classification of,
534
development of, 580
Coraco-acromial ligaments, 136
Coraco-brachialis muscle, 212
Coraco-clavicular ligament, 135
Coraco-humeral ligament, 137
Coracoid («opa|, a raven ; fiSos, shape)
process of scapula, 76
Cord, genital, 996
gubernacular, 1000
spermatic, 963. See SPERMATIC
COED
spinal. See SPINAL CORD
Cordiform (cor, the heart ; forma, shape)
tendon of diaphragm, 245
Corium (skin), cciii
blood-vessels and lymphatics of, ccv
chemical composition of, ccvi
development of, ccvi
nerves of, ccvi
papilke of, cciv
structure of, cciii
of mucous membrane, cxcvii
Cornea (corneus, horny), 714
opaca, 711
structure of, 715
nerves and vessels of, 716
Cornicula laryngis, 908
of hyoid bone, 52
Cornu Ammonis, 544
Cornua of hyoid bone, 52
sacral, n
sphenoidal, 40
of thyroid cartilage, 906
of ventricles of brain, 543
Corona glandis, 955
radiata, 556
Coronal suture, 54
Coronary arteries. See ARTERIES
ligament, 827, 865
plexus. See PLEXUS
sinus, 310
vessels, 321
Coronoid fossa of humerus, 80
process of lower jaw, 52
of ulna, 82
Corpora albicantia, 537
development of, 581
Corpora Arantii, 308, 313
Corpora cavernosa clitoridis, 977
Corpora cavernosa penis, 956
arteries of, 428, 958
bulbs of, 956
covering of, 957
septum of, 956
structure of, 956
trabeculae. of, 957
veins of, 958
Corpora geniculata, 554
Corpora mammillaria, 537
Corpora Morgagni, 968
Corpora quadrigemina, 552
development of, 578
grey matter of, 561
Corpora striata, 550
development of, 580
grey matter of, 561
Corpus callosum, 530, 541
convolution of, 532
development of, 581
fibres of, 543, 557
peduncles of, 539, 542
Corpus ciliare, 515
Corpus dentatum of cerebellum, 526
of olivary body, 515
Corpus fimbriatum, 544, 546
Corpus Highmorianum, 968
Corpus luteum, 990
Corpus spongiosum urethrse, 958
structure of, 959
Corpuscles (corpuscuhim, pi. -a, dim. from
corpus, a body) of blood, red,
xxviii
chemical composition of, xxxiii,
xli
formation of, 1
proportion of, in blood,
xxxvi
shape and size of, xxviii
structure of, xxix
pale, xxxi
of chyle, xlix
formation of, 1
of connective tissue, Ixxiii
ganglionic, cxxxix
of lymph, xlviii
formation of, 1
Malpighian, of kidney, 930
of spleen, 887
of muscle, cxxi
of nervous substance. See Nerve-cells
tactile, cl, cli, ccvi
of thymus gland, 924
of thyroid body, 922
Corpuscula tactus, cli, ccvi
Corrugator muscle, 1 73
Corti, membrane of, 761
organ of, 761, 764
rods or fibres of, 764
Cortical substance of brain, 555
of kidney, 929
of lymphatic glands, clxxxvii
of suprarenal bodies, 939
Costse or ribs, 24
of scapula, 76
Costal cartilages, 26
structure of, Ixxxiii
Costo-clavicular ligament, 134
Costo-central ligaments, 128
Costo-coracoid ligaments, 229
Costo- sternal ligaments, 130
Costo-transverse ligaments, 129
Costo-vertebral ligaments, 128
Costo-xiphoid ligaments, 130
Cotunnius, liquor of, 757
nerve of, 604
Cotyloid (KorvX-n, a cup ; etSos, shape)
cavity and notch, 96
ligament, 152
1100
INDEX,
Cowper's glands, 963
development of, 1001
CRANIAL NERVES, classification of, 582
distribution of, 587
origin of, 583
first pair, (o) 583, (d) 592
second pair, (o) 584, (d) 592
third pair, (o) 586, (d) 593
fourth pair, (o) 586, (d) 594
fifth pair, (o) 586, (d) 595
sixth pair, (o) 586, (d) 610
seventh pair, (o) 587, (d) 610
eighth pair, first part, (o) 520, 587,
(d) 615
second part, (o) 520, 587, (d)
618
third part, (o) 519, 587, (d) 625
ninth pair, (o) 519, 587, (d) 626
Cranial sinuses, 461
Cranio- vertebral cavity, development of,
Cranium (itpaviov, the skull), 29
dissection of integument of, 1048
of interior of, 1049
of parts at base of, 1058
Creatin and creatinin (Kpeas, flesh), xl,
cxxviii
Cremaster (/epe^uaw, I suspend), 251, 965,
1022
formation of, 1000
Cremasteric artery, 433
fascia, 965
Crest of bone, Ixxxviii
external occipital, 30
nasal, 45
of ilium, 94
of os pubis, 95
Cribriform, (cribram, a sieve ; forma,
shape) fascia, 293, 1033
lamella of ethmoid bone, 43
of sclerotic, 712
of temporal bone, 38
Crico-arytenoid articulation, 910
muscles, 914
Cricoid (Kpiicos, a ring ; etSos, shape) car-
tilage, 906
Crico-thyroid artery, 348
ligaments, 909
muscles, 914
Crispation (crispus, crisp or curled),
viii
Crista frontalis, 35
galli (cock's comV, 42
pubis, 95
ure three, 961
vestibuli, 754
Crotaphite (KPOTO.QOS, the temple), 181
Crucial (crux, a cross) ligaments, 155
Cruor, xxxiv, xxxv
Crura of corpora cavernosa, 956
cerebri, 536
development of, 578
grey matter of, 561
cerebelli, 521, 522
development of, 577
Crara of clitoris, 977
of diaphragm, 243
of fornix, 545, 546
of penis, 956
Crural arch, 1033
deep, 258, 1033
canal, 293, 1034
septum, 1034
sheath, 293
Crureus muscle, 276
Crust of cerebral peduncle, 556
Crusta petrosa, 791
Crypt (KPVTTTG), 1 conceal), ccxxii
multilocular, ccxxii
Crypts of Lieberkiihn, 845
Cryptorchismus (/C/WTTTCO, I conceal ;
opxis, a testicle), 966
Crystalline (Kpva-ra\\os, ice or crystal)
lens, 733. See Lens
Crystalloid substances, Graham's re-
searches on, vi
Cuboid (KV&OS, a cube ; et'Sos, shape)
bone, 108
ligaments of, 162, 163
Cucullaris (cucullus, a hood) muscle,
200
Cul-de-sac of pleura, 894
recto-vesical, 857
of stomach, 831
Cuneiform (cuneus, a wedge ; forma,
shape) bones of foot, 109
ligaments of, 163, 165
of hand, 84
cartilages, 905
process of ethmoid bone, 43
Cupola, 756
Cuspidate (cuspis, the point of a weapon)
teeth, 781
Cuticle (cutis, the skin), cci
development of, ccvi
nutritive changes in, xxv
of enamel, 791
Cutis vera (true skin), cciii. See Coriuin
and SKIN
Cuvier, ducts of, 483
Cylinder axis. See Axis, Cylinder
epithelium, Ivi
Cylindrical bones, Ixxxvii
Cystic (KVOTIS, a bladder) artery, 408
duct, 868, 878
Cytoblast (/euros, a cell ; /3Aoo-ros, a
germ), xix
Cytoblastema (KVTOS, a cell ; /3\acrTauo,
I germinate), xix
Cytogenous (/euros, a cell ; yevvao), I
produce) connective tissue, Ixxix
DARTOS (Sopros, the skin of scrotum ;
Sepco, I flay), 257, 964
fibres of, cxxvi
Decussation (decusso, I cut cross-wise)
of optic nerves, 584
of pyramids, 515
De Graaf, vesicles of, 989
Deiters, cells of, 767
IXDEX.
1101
Deltoid (AeiVra, the letter A, or delta ;
ei'Sos, shape) muscle, 208
Demours, membrane of, 715
Dens sapientue (wisdom tooth), 783
Dental arches, 780
artery, 356
canal, 52
foramen, 52
glands of Serres, 800
grooves, 793
nerves, 60 1, 608. See also TEETH
Denticulate ligament, 566
Dentine (dens, a tooth), 785
development of, 797
secondary, 792
Depressor. See MUSCLES
Derma (Sep^o, skin), cciii
Descemet's membrane, 715
Descent of testicle, 1000
Detrusor (de, down ; trudo, I thrust)
muscle, 949
DEVELOPMENT of the several organs and
tissues. See under these.
Dialysis (Sto, apart ; Auw, I loosen), vi
Diaphragm (Sta, between ; Qpavcria, I
fence), 243
action of, 247
pelvic, 263
Diaphragma oris, 184
Diaphragmatic nerve, 640
plexus, 699
Diaphysis (8m, between ; $ya>, I grow),
Ixxxviii
Diapophysis (Sjo, apart ; apopTiysis), 22
Diarthrosis (Sta, between ; apdpov, a joint),
119
Diencephalon (Sta, between ; eyiccQaXov,
the brain), 577
Digastric (Sis, twice ; yavT-rjp, a belly)
muscle, 183
nerve, 613
Digestion, organs of, 779
function of columnar epithelium in,
Ivii
Digital arteries. See ARTERY
nerves. See NERVE
Dilatator. See MUSCLES
Diploe (8iir\ovs, double), xc, 60
veins of, 465
Discus proligerus (proles, progeny ; gero,
I bear), 990
Disdiaclasts (Sis, twice; StawAaa?, I break),
cxx
DrssECTTON, general management of,
1047
of abdomen, 1069
cavity of, 1072, 1074
viscera of, 1073
wall of, anterior, 1070
upper and posterior, 1075
of ankle-joint, 1085
arm, deep, 1064
superficial, 1063
axilla, 1 06 1
back, muscles of, 1 060
I DISSECTION — continued.
of brachial region, 1064
brain, 1049
cervical region, 1052
cranium, integument of, 1048
interior of, 1049
parts at base of, 1058
face, deep, 1055
superficial, 1054
fifth nerve, 1057
foot, articulations of, 1085
dorsum of, 1084
sole of, 1083
forearm, articulations of, 1066
front, 1064
posterior, 1065
genital organs, female, 1076
male, 1072
gluteal region, 1078
hand, articulations of, 1066
front, 1065
posterior, 1065
head and neck, 1048, 1059
heart, 1067
hip-joint, 1082
knee-joint, 1085
larynx, 1059
leg, back of, 1082
front of, 1084
limb, lower, 1078
upper, 1059
mediastinum, posterior, 1068
nares, 1059
neck, anterior, 1053
deep, 1059
posterior, 1052
orbit, 1056
palate, 1058
pectoral region, 1061
pelvis, 1076
ligaments of, 1078
viscera of, 1077
pericardium, 1067
perineum, 1069
deep, 1040
peritoneum, 1072
pharynx, 1058
pleura, 1066
popliteal space, 1079
scapular muscles, 1062
shoulder-joint, 1064
spinal cord, 1060
sublingual region, 1057
submaxillary region, 1057
thigh, front of, 1080
thorax, 1066
articulations of, 1069
tongue, 1058
Dlverticulum (from diverto, I turn aside)
of ileum, 841
Dolichocephalic (8o\ixos, long ; Kf(pa\rj,
the head) skulls, 73
Dorsal artery. See ARTERY
ligaments. See LIGAMENT
nerves. See NERVES
1102
INDEX.
Dorsal veins. See VEINS
vertebrae, 5
Dorse-lumbar (dorsum, the back ; lum-
bus, the loin) nerve, 658
Douglas, semilunar fold of, 25 1
Drum of ear, 744
Duct, bile, common, 868
cystic, 868, 878
hepatic, 867
Mullerian, 996
nasal, 709, 710
pancreatic, 882
supplementary, 883
parotid, 816
Stenson's, 816
of submaxillary gland, 817
thoracic, xlvii, cxc, 487
right, 488
vitelliue, 859
Wharton's, 817
of Wolffian body, 992
Ductless glands, ccxxvi
Ducts of glands, in general, ccxxv
of Bellini, 930
biliary, 875
aberrant, 877
of Cuvier, 483
ejaculatory, 974
galactophorous, 1003
he pato- cystic, 869
of kidney, 930
of Eivini, 818
seminal, 974
of sublingual gland, 818
of sweat-glands, cclxxv
Ductus ad nasum, 710
arteriosus, 327, 328
closure of, 331
cochlearis, 761
communis choledochus, 868
venosus, 328, 483
fossa of, 864
Duodenum (duodeni, twelve ; from being
twelve finger-breadths in length),
839
development of, 86 1
dissection of, 1073
position of, 824
Dura mater, 562
development of, 581
structure of, 564
Dynamometer (Swa/m, strength ; fj-frpov,
a measure), 235
EAR, 740
development of, 768
dissection of, 1057
external, 740
auditory canal of, 743
structure of, 744
vessels and nerves of, 744
pinna of, 740
cartilage of, 741
ligaments of, 742
muscles of, 1 70, 742
E A R — continued.
pinna, nerves of, 743
vessels of, 743
internal, 753. See LAEYIUNTH
memijranous, 757
osseous, 753
vessels of, 767
middle, 744. See TYMPANUM
bones of, 748
ligaments and muscles of, 749
lining membrane of. 751
vessels and nerves of, 752
Ear-wax, 744
Efferent nerves, cxxxii, clxii
vessels of kidney, 931
Ejaculate r. See MUSCLES
Ejaculatory ducts, 974
Elastic cartilage, Ixxxi, Ixxxv
fibres of areolar tissue, Ixx
lamina of cornea, 715
tissue, Ixxvi
in arteries, clxix, clxx
Elbow, bones of, 79, 82
ligaments of, 140
movements of, 141
Electricity, manifestation of by muscles,
cxxix
Elements, structural, of human body, iv
Eminence, frontal, 33
ilio-pectineal, 96
jugular, 31
nasal, 34
parietal, 32
supracondyloid, 79
Eminences of bones, Ixxxviii
Eminentia collateralis, 544
papillaris, 746
pyramidalis, 754
Emotion, a stimulus of muscular action,
cxxx
to nervous tissue, cxxxii
Emulgent (emulgeo, I milk or drain out)
arteries, 414
Enamel membrane, 797
organ, 797
of teeth, 785, 789
development of, 798
Enarthrosis (eV, in ; apQpov, a joint), 120
ENCEPHALOX (eV, in ; /ce^oArj/the head),
5'3
blood-vessels of, 363, 370, 548, 567
development of, 575
grey matter of, 519, 527, 559
internal structure of, 526, 555
membranes of, 562
development of, 581
primary divisions of, 513
specific gravity of, 574
weight of, 568
parts of, 571
End-bulbs of nerves, cli, ccvi
Endocardium (evSov, within ; KapSia, the
heart), 304
Endolymph (tvSov, within ; lympJia,
water), 757
INDEX.
1103
Endosteum (evSov, within ; oa-reov, a
bone), c
Ensiform (ensis, a sword ; forma, shape)
cartilage, 33
Epencephalon (e?n, on ; eyKetyaXov, the
brain), 577
Ependyrua (e-n-i, on ; JvSu/ia, clothing), 543
Ephippiuni (tfynr-niov, a saddle), 39
Epicojidyle (eVt, on ; condyle), 79
Epicranial (eVt, on ; Kpaviov, the skull)
muscles, 169
Epidermis (eVt, on ; 8ep/j.a, the skin), lii,
cci
Epididymis (fin, on ; SiSujUor, a testicle),
canal of, 971
development of, 999
Epigastric (em, on ; yavrtip, the stomach)
artery. See ARTERY
region, 824
contents of, 826
Epiglottis (fin, on ; glcttis\ 908
tubercle or cushion of, 911
Epihyal (eVi, on ; hi/oid bone) bone, 133
Epiphysis(e7Ti, on; <f>vw, I grow), Ixxxviii
Epiphyses, formation of, cxii
Epiploical (epiploon, a name sometimes
given to the omentuai, from eVi-
irAcco, I sail, or float on) appen-
dices, 830
Episternal (tjn, on ; arepvov, the breast)
nodules, 24
EPITHELIUM (eV<, on ; 6a\\w, I grow) in
general, lii
of air-passages, lix, 900
alveoli of lungs, 900
arachnoid, 566
arteries, clxix
bile-ducts, 877
bronchia, 900
capillaries, clxxvii
capsules of Malpighian bodies,
932
choroid, 718
ciliated, Iviii
columnar, Ivi
of conjunctiva, 708
cornea, 715, 716
crypts of Lieberkuhn, 846
ducts of glands, Ivii, Iviii, ccxxv
endocardium, 304
Eustachian tube, 751
eye-ball, liv
Fallopian tube, 992
flattened, liii
furrowed and spinous cells of, Iv
of galactophorous ducts, 1004
gall-bladder, Ivii, 878
glomeruli of kidney, 932
glandular, Iviii
of intestines, Ivii
large, 856
iris, 719
labyrinth, 757
lachrymal sac and duct, 710
EPITHELIUM— continued.
lamellar, liii
of larynx, 918
lymphatics, clxxxiv
Meibomian glands, 707
membranous labyrinth, 758
mouth, liv
mucous membranes, Ivii, cxcvii
nasal fossae, 775
nerve-filaments in, clvi
nutrition of, xxv
of oesophagus, liv, 823
palate, 813
parotid duct, 816
pavement, liii
of pericardium, liii
peritoneum, liii
pharynx, 821
pleura, liii
prostatic gland and ducts, 954
scaly, liii
of seminiferous tubes, 971
serous membranes, liii, cxcii
spheroidal, Iviii
of stomach, Ivii, 837
stratified, liv
of synovial membranes, cxciv
tabular, liii
tesselated, liii
of throat, liv
tongue, liv, 808
trabeculse of corpora cavernosa, 957
trachea, 892
transitional, Iviii
of tubuli of stomach, 837
tympanum, 751
ureters, 943
urethra, liv, Ivii, 962
urinary bladder, 951
uriniferous tubules, 930
uterus, liv, lix, 985
vagina, liv, 982
vas deferens, 972
vascular system, liii
veins, cclxxiii
ventricles of brain, 543
vesiculae seminales, 974
villi of intestine, 844
vulva, liv, 978
Epitrochlea (fin, on ; trochlea), 79
Equivocal cell-generation, xix
ERECTILE TISSUE, general characters of,
clxxx
of penis, 955
vulva, 979
Erector. See MUSCLES
Ergot (Fr. a spur), 544
Ethmoid (r?0/itos, a sieve ; elSos, shape)
bone, 42
development of, 69
Eustachian canal, 38, 59
tube, 59, 747
valve, 309
development of, 325
Excito-motory movements, cxxxii
1104
INDEX.
Excretion, ccxix
Expiration, physiology of, 248
Extension, 120
of wrist, 228
Extensor. See MUSCLES
Extremities. See LIMIJS
EYE, 705
appendages of, 705
aqueous humour of, 737
ball or globe of, 710
chambers of, 737
ciliary muscle, 721
circular sinus, 721
coats of, external, 711
middle, 716
development of, 737
lachrymal apparatus, 709.
lens of, 733
ligamentum pectinatum, 721
membranes, 711
of Bruck, 717
of capsule of lens, 733
choroid, 716
conjunctiva, 708
cornea, 714
of Demours or Descemet, 715
hyaloid, 731
iris, 718
Jacob s, 726
pigment, 718, 719
pupillary, 721
retina, 725
Ruysch's, 717
sclerotic, 711
muscles moving the, 1 79
nerve of. See NERVE, Optic ; and
Retina
refracting media of, 711
shape and size of, 711
vessels and nerves of, 721
vitreous body of, 731
Eyelashes, 707
Eyelids, 705
cartilages of, 706
conjunctiva of, 708
development of, 739
fissure of, 705
glands of, 707
ligaments of, 707
muscles of, 171
structure of, 706
Eye-teeth, 782
FACE, bones of, 44
dissection of, 1054
formation of, 66
muscles of, 173, 174
veins of, 455
Facial angle, 73
artery, 349
nerves, 587, 589, 610
Faisceaux innomines (Fr. unnamed
bundles), 518
Falciform (falx, a sickle or scythe ', forma,
shape) process, 1032
Fallopian tubes, 991
development of, 997
position of, 825
Fallopius, aqueduct of, 38
hiatus of, 38, 6 1
ligament of, 249
False membrane, cxciii
pelvis, 97
ribs, 24
Falx cerebelli, 524
cerebri, 523
Fang of tooth, 780
FASCIA (a band), Ixxiv, 168
abdominal, 257
anal, 260
of arm, 229
axillary, 230
cervical, deep, 197
superficial, 196
of Colles, 259
cremasteric, 253, 965
cribriform, 293, 1031
deep, 1 68
dentata (dentated band), 548
dorsal, 240
of foot, 296
of fore -arm, 230
hand, 231
head and neck, 196
iliac, 259
infundibuliform, 258, 965
intercolumnar, 250, 965, 1020
lata (broad fascia), 292, 1032
of leg, 295
lower limb, 292 '
lumbar, 240
masseteric, 197
obturator, 261
palmar, 231
parotid, 197
of pectoral region, 229
pelvic, 260
permeal, deep, 260, 1040
superficial, 259, 1039
plantar, 296
prevertebral, 198
propria, femoral, 1035
inguinal, 965
recto-vesical, 260
spermatic, 965, 1020
subpubic, 1040
superficial or subcutaneous, 168
of groin, 1018, 1031
temporal, 197
trausversalis, 258, 1022
of upper limb, 229
Fascicle (fasciculus, dim. from fascis, a
bundle), round, 519
Fasciculi graciles (slender fascicles), 516,
5i8
teretes (round fascicles), 517, 518,
52 J
of muscle, cxvii
Fasciculus cuneatus (wedge-shaped fas-
cicle or bundle), 516
INDEX.
110-3
Fasciculus — continued.
olivary, 516, 519, 521, 577
uncinatus (hook- shaped fascicle), 558
FAT, Ixv
cells, Ixvi
chemical composition of, Ixvii
development of, Ixviii
distribution of, Ixv •
uses of, Ixviii
Fatty matters, vi
of blood, xl
Fauces (the throat), 779
isthmus of, 190
pillars of, 189
Femoral (femur, the thigh) arch, 1031
deep, 258, 1033
artery. See ARTERY
canal, 293, 1034
hernia. See Hernia
region, anterior, muscles of, 273
posterior, muscles of, 270
ring, 1033
vessels, sheath of, 1033
Femur, 100
compared with humerus, 116
ossification of, in, 112
Fenestra (a window or opening) ovalis,
745
rotunda, 706
Fenestrated (perforated) membrane of
arteries, clxix
Ferrein, pyramids of, 929
Fibra prirnitiva (primitive band), cxxxvi
Fibrse arciformes, 517
Fibres, axial, of nerve-tubes, cxxxvi
of cerebellum, 527
of cerebrum, 555
of Corti, 764
dental, 787
of lamellae of bone, xcv
of medulla oblongata, 518
Miilleriau, in retina, 728
of muscle, cxvii
structure of, cxviii
branched, cxxi
of nerve-tissue. See NERVE-FIBRES
nuclear, Ixxi
of roots of spinal nerves, 511
Fibre- cells of involuntary muscle, cxxiv
in small vessels, clxxviii
Fibril (dim. of fibra, a fibre) of muscle,
cxviii
Fibrillation of areolar tissue, Ixxii
Fibrin (fibra, a fibre), vi
of blood, xxvii, xxxii, xxxvii
origin of, xxxviii
of chyle, xlix
Fibrinogen (fibrin; yevvaca, I produce),
xxxix
Fibrinogenous^Jrm ; yevvaw, I produce)
substance, xxxix
Fibrinoplastic ( fibrin; 7rAa<r(ra>, I form)
substance, xxxix
Fibrinoplastin (fibrin ; ir\a<Tffu, I form),
Fibro- cartilage, Ixxxvi
intervertebral, 121
of knee, 155
of lower jaw, 133
pubic, 149
radio-ulnar, 138
scapulo-clavicular, 135
sterno-clavicular, 134
Fibro-serous membrane, cxcii
Fibrous cone, 556
structure of heart, 316
tissue, Ixxiv
Fibro-vascular layer of corium, cciii
mucous membrane, cxcvii
Fibula (a brace, a clasp), 105
ligaments of, 158
ossification of, in, 115
Fila acoustica, 757
Filamentous tissue, Ixix
Filaments of areolar tissue, Ixxi
of fibrous tissue, Ixxv
spermatic, 976
Filiform papillae of tongue, 807
Fillet, 519, 557
of corpus callosum, 557
Filum terminale of spinal cord, 502, 505
Fimbrise (fringes) of Fallopian tube, 991
Fimbriated (fringed) extremity of Fallo-
pian tube, 991
Fingers, bones of, 87
development of, 90, 93
fascia of, 222
muscles of, 217
Fissiparous (findo, I cleave ; pario, I pro-
duce) propagation of cells, xvii
Fissura palpebrarum, 705
Fissure, calcarine, 536
of cerebellum, 523
of cerebrum, longitudinal, 530
convolution of, 533
internal perpendicular, 536
transverse, 547
vertical, 534
of ductus venosus, 864
of Glaser, 36, 37
of hippocampi, 533
incisor, 69
of kidney, 927
longitudinal, of liver, 864
occipital, 536
portal, 864
ptery go-maxillary, 57
of Rolando, 533
sphenoidal, 41, 57, 61
position of nerves in, 594
Sylvian, 530, 535
convolution of, 532
development of, 581
transverse, of liver, 864
umbilical, 864
of vena cava, 864
Fissures of liver, 864
of medulla oblongata, 514
of Santorini, 742
of spinal cord, 506
4 c
1106
INDEX.
Flat bones, Ixxxviii
Flattened epithelium, liii
Flesh, chemical composition of, xxxiii
Flexor. See MUSCLES
Flexure, hepatic, of colon, 853
sigmoid, of colon, 854
position of, 825
splenic, of colon, 854
Floating ribs, 26
Flocculus (dim. offloccus, a lock of wool),
524, 577
Fluid, cerebro-spinal, 566
prostatic, 954
of serous cavities, cxciii
Foetus, circulation in, 328
lens in the, 735
peculiarities of heart in, 327
liver in, 879
lungs in, 904
Folds, arytseno-epiglottidean, 910
glosso- epiglottic, 805
recto-uterine, 986
recto-vesical, 947
vesico-uterine, 986
Follicle (folliculuS) dim. offollis, a bag),
ccxxii
of hair, ccix
muscular fibres of, ccxi
Follicles, closed, of intestines, 856
lenticular, of stomach, 837
of teeth, 793
Follicular stage of development of teeth,
793
Fontanelles (fons, a fountain), 67
Foot, articulations of, 160
bones of, 106
compared with hand, 115
ossification of, no, 115
dissection of, 1082, 1084, 1085
fascia of, 296
muscles of, 279
nerves of, 683, 684
vessels of, 446, 450
Foramen (foro, 1 pierce), carotid, 37, 59
caecum of frontal bone, 35, 61
of medulla oblongata, 514
of tongue, 805
commune anterius of brain, 546
dental, inferior, 53
incisor, 44, 45
infraorbital, 45, 56
jugular, 59
labial, 51
lacerum anterius basis cranii, 59
jugulare, 31
orbitale, 41, 57
posterius basis cranii, 38, 59, 61
magnum, 29, 61
mastoid, 37
mental, 51, 56
of Monro, 546
obturator, 93, 96
occipital, 29, 6 1
optic, 41, 6 1
ovale of sphenoid, 42, 59, 6 j
Foramen — continued.
ovale of heart, 325, 328
closure of, 331
vestige of, 309, 312
of pelvis, 93, 96
parietal, 32
rotuudum, 42, 57» 61
sacro-sciatic, great and small, 149
spheno-palatine, 48, 58, 63
spinosum, 42, 59, 61
stylo-mastoid, 37
supraorbital, 54, 56, 57
suprascapular, 76
thyroid, 93, 96
of a vertebra, 5
of Winslow, 827
Foramina of right auricle, 308
condyloid, anterior, 31
posterior, 31
of diaphragm, 246
of ethmoid bone, 43, 6 1
intervertebral, 5
malar, 49, 56, 57
of nasal cavities, 61
orbital, anterior and posterior, 34, 57
palatine, anterior and posterior,
45,59
small, 47, 59
sacral, anterior, n
posterior, n
of Scarpa, 45
of Stenson, 45
Thebesii, 309
Force, nervous, clxiii
Forces, vital, vii
Fore-arm, aponeurosis of, 230
articulations of, 138
bones of, 83
compared with foot, 115
development of, 99
dissection of 1065
muscles of, 215, 218
nerves of, 648, 685
vessels of, 389, 395
Foreskin, 955
Form of pelvis, varieties in, 100
of skull, varieties of, 72, 73
of vertebral column, 14
Fornix (an arch or vault), 543, 545
bulbs of, 537
development of, 581
fibres of, 559
Fossa of antihelix, 741
canine, 45, 55
coronoid, 80
cystis fellese (fossa of the gall-blad-
der), 865
digastric, 36
digital, 101
ductus venosi, 864
of gall-bladder, 865
glenoid, 36, 57
guttural, 59
of helix, 741
iliac, 95
INDEX.
1107
Fossa — continued.
incisor of upper jaw, 45, 55
of lower jaw, 51
infraspinous, 74
innominata, 741
intercondyloid, 102
ischio-rectal, 261, 1043
jugular, 37
lachrymal, 34
myrtiform, 45
navicular, 41
navicularis of urethra, 962
vulva, 977
olecranon, 80
ovalis of heart, 309
of antihelix of ear, 741
pituitary, 39
pterygoid, 41
recto-vesical, 825
scaphoidea (boat-shaped fossa), 741
spheno-maxillary, 57
subscapular, 74
supraspinous, 74
temporal, 57
triangularis, 741
trochanteric, 101
of vena cava, 864
zygomatic, 57
Fossae, inguinal, of peritoneum, 1024
of liver, 864
nasal, 61, 773
occipital, superior and inferior, 31
of skull, internal, 61
Fourchette (a fork), 977
Fovea (a pit or depression) centralis, 726
hemielliptica, 754
hemispherica, 754
ovalis, 309
trochlearis, 34
Fovese glandulares, 33
Foveola (dim. of fovea, a pit) of renal
papillae, 930
Foville's classification of cerebral convo-
lutions, 534
researches on fibres of cerebrum,
588
Frasna (pi. of frcenum, a bridle) of ileo-
caecal valve, 853
of lips, 779
syiiovial, cxcv
Frsenula, glosso-epiglottic, 805
of lips. See Frsena
Frsenulum (dim. of frcenum, a bridle)
cerebri, 554
pudendi, 977
Frjenum epiglottidis, 805
linguae, 805
of prepuce, 955
Free ribs, 26
Frontal (frons, the forehead) bone, 33
ossification of, 67, 70
lobe of cerebrum, 535
processes in embryo, 65
sinus, 34, 64
suture, 55, 67
Fronto-parietal suture, 54
Fundus (the bottom of any thing) of
bladder, inferior, 944, 946
superior, 945
of gall-bladder, 868
stomach, 831
uterus, 983
Fungiform ( fungus, a mushroom ; forma,
shape) papillaa of tongue, 807
Funiculus (dim. offunis, a cord) of nerve,
cxliv
Furcula (dim. off urea, a fork), 24
Furrowed band, 525
cells of epithelium, lv
Furrows of heart, 303
GAERTNER, canals of, 992, 998
Galactophorous (ya\a, milk : #epw, I
carry) ducts, 1003
Gall-bladder, 868
development of, 879
structure of, 878
varieties of, 868
GANGLIA, General Anatomy of, cxxxii,
cxli
structure of, cxlii
connection of nerve-fibres with, cxlii
of auditory nerve, cxlix
of cardiac nerves, 699
cranial, 688
of glosso-pharyngeal nerve, 616
lumbar, 696
lymphatic, clxxxvi
mesaraic, 702
of pneumo-gastric nerve, 618
sacral, 696
semilunar, 699
of spinal nerves, 630
sympathetic nerves, clviii, 686
thoracic, 693
of nerves of tongue, 812
vascular plexuses, 692
Gangliated cord, sympathetic, 686
cervical part, 688
lumbar part, 696
sacral part, 696
thoracic part, 693
GANGLION, Arnold's, 608
Bochdalek's, 602
cervical, lower, 693
middle, 692
upper, 688
ciliare, 599
diaphragmatic, 699
on facial nerve, 611
of fifth pair, or Gasserian, 596
geniculate, 6n
impar, 693
intercaroticum, 692
jugular, 616
lenticular, 599
Meckel's, 603
ophthalmic, 599
otic, 608, 1057
4 c 2
1108
INDEX.
GANGLION — continued.
petrous, 616
semilunare (syn. of the ophthalmic
or lenticular ganglion), 599
spheiio-palatine, 603, 1057
splanchnico-suprarenale, 699
subm axillary, 609
thyroid, 692
of Wrisberg, 698
Ganglion-globules, cxxxix
connection of nerves with, cxlii
Ganglionic corpuscles, cxxxix
nerves, cxxxiii, clviii
Gasserian ganglion, 596
Gastric (ycurrijp, the stomach) artery,
409
nerve, 623
Gastrocnemius (yaffTijp, the belly ;
the leg) muscle, 283
Gastro-colic (yaa-TTjp, the stomach ;
the colon) omentum, 829
Gastro-duodenal (ya<rri)p, the stomach ;
duodenum) artery, 408
Gastro-epiploic (yao-r-rip, the stomach ;
epiploon, the omentum) arteries,
408, 410
Gastro-hepatic (yao-riip, the stomach ;
7iirap, the liver) omentum, 827
Gastro-phrenic (yaarrrjp, the stomach ;
0/n/j/, the diaphragm) ligament,
829
Gastro-pulmonary (ycurrrip, the stomach ;
pulmoy a lung) mucous membrane,
cxcvi
Gastro-splenic (yaa-r-np, the stomach ;
CTTTATJJ/, the spleen) omentum,
829
Gelatin, vi, Ixxiii, Ixxviii
Gelatinous nerve-fibres, cxxxviii
principles, vi
Gemellus (twin) muscle, 269
Generative organs, female, 977
male, 952
development of, 995
Genial (yeveiov, the chin) tubercles, 185
Genio-hyo-glossus (ytveiov, the chin ;
y\w<r<ra, the tongue) muscle, 185
Genio-hyoid (yfvciov, the chin ; voeiSrjs,
hyoid bone) muscle, 185
Genital cord, 996
nerve-corpuscles, cli
organs, dissection of, 1072, 1076
Genito-crural nerve, 660
Genito-urinary mucous membrane, cxcvi
muscles, 263
Genu (a knee) of the corpus callosum, 542
Germinal matter, xxiv
membrane, 15
spot, xv, 990
vesicle, xv, 990
Gestation (geslo, I bear or carry), changes
in uterus during, 987
Gimbernat's ligament, 250, 1031
Gingivse (gums), 780
Ginglymus (yiyyXvfji.os, a hinge), 120
Giraldes, organ of, 973, 1001
Glabella (dim. of glabra, fern, of glaber,
smooth), 34
GLANDS (glans, an acorn), Secreting,
General Anatomy of, ccxviii
acini of, ccxxiv
agminated, cc
compound, ccxxii
conglobate, cc
conglomerate, ccxxiv
crypts, ccxxxii
ducts of, ccxxv
envelope of, ccxxv
follicles of, ccxxii
follicular, cc
formation of, ccxxi
forms of, ccxxii
lacunae of, ccxxii
lobules of, ccxxii
lymphatics of, ccxxiv
of mucous membrane, cc
multilocular crypts, ccxxii
nerves of, ccxxv
racemose, ccxxii
reservoirs of, ccxxv
saccular, ccxxii
simple, ccxxii
solitary, cc
substance of, ccxxv
tubular compound, ccxxiv
simple, cc
vessels of, ccxxv
Glands, ductless, General Anatomy of,
ccxxvi
enumeration of, ccxxvi
structure of, ccxxvi
varieties of, ccxxvi
GLAND or GLANDS, antiprostatic, 963
arytenoid, 919
of Bartholin, 978
of bile-ducts, 877
Brunner's, 849
buccal, 780
ceruminous, 744
coccygeal, 697
Cowper's, 963, 1001
dental, 800
of Duverney, 978
epiglottidean, 919
gastric lenticular, 837
tubular, 836
kidney, 926. See KIDNEY
labial, 779
lachrymal, 709
of large intestine, 856
laryngeal, 918
of laryngeal pouches, 913
Littre, 963
liver, 862. See LIVER
mammary, 1002
Meibomian, 707
molar, 780
of mucous membrane, cc
of iiose, 775
ossophageal, 823
INDEX.
1109
GLAND, or GLANDS— continued.
palatine, 813
pancreas, 88 1. See PANCREAS
parotid, 814. See PAROTID
peptic, 837
of Peyer, 841, 846
of pharynx, 820
pineal, 552, 579
pituitary, 539
of prepuce, 955
prostate, 952. See PROSTATE
anterior, 963
salivary, 814
sebaceous, ccxvii
of skin, ccxv
small intestine, 845
solitary, cc, 849
sublingual, 817
submaxillary, 816
sudoriferous, ccxvi
suprarenal, 939
thymus, 923. See THYMUS
thyroid, 920. See THYROID
of tongue, 805, 809
tracheal, 892
of Tyson, 955
urethra, 962
uterine, 985
Wolffiau (fostal), 992
GLANDS, LYMPHATIC, General Anatomy
of, clxxxvi
Descriptive Anatomy, 486
axillary, 497
bronchial, 495
cardiac, 495
cervical, 499
iliac, 490, 491
inguinal, 489
intercostal, 495
lumbar, 491
mediastiual, 495
mesenteric, 491
cesophageal, 495
popliteal, 489
sacral, 491
of thorax, 495
Glandula intercarotica, 692
socia parotidis, 815
Glandulse Pacchioni, 567
ceruminosse, 744
solitaries of the intestine, 849
Glans (an acorn) clitoridis, 977
penis, 955
Glaser, fissure of, 36, 37
Glenoid (yXijmr), a shallow pit of a bone ;
flSos, shape) cavity of scapula,
76
fossa of temporal bone, 36, 57
ligament, 137
Glisson's capsule, 867, 870
Globulin, xxxiv, xxxix
action of, in coagulation, xlvi
characters of, xxxv
Globus major and minor of the epidi-
dymis, 968
Glomerulus (dim. of glomus, a clue of
thread) of kidney, 931
Glosso-epiglottic (y\w(T<ra, the tongue ;
epiglottis) folds or frsenula, 805
Glosso-pharyngeal (yXoxrffa., the tongue ;
<pa/>try|, the pharynx) nerve,
519, 589, 615
ganglia of, 616
Glottis (y\<i>TTis, a tongue), 911
Glutseus (y\ovros, the buttock). See
MUSCLES
Gluteal artery, 429
muscles, 266
nerve, 667, 673
Glycogen (y\vKvs, sweet ; ytwau, I pro-
duce), vi
Goll, bands of, 535
Goinphosis (yontyos, a nail), 119
Graatian vesicles, 989
Gracilis (slender) muscle, 276
Graham's researches on dialysis, vi
Granular layer of dentine, 789
of retina, 727
Granules (granum, agrain), elementary, iv
in blood, xxxii, xliii
in nerve-substance, cxl
in muscular fibre, cxxi
Gratiolet's classification of cerebral con-
volutions, 535
Grey matter of cerebellum, 527
of cerebrum, 559
medulla oblongata, 519
pons Varolii, 521
spinal cord, 509
Gristle, Ixxx
Groin, anatomy of, 1018
Groove, bicipital, 78
dental, 793
for Eustachian tube, 59
lachrymal, 46
musculo-spiral, 79
mylo-hyoid, 52
occipital, 37
scapular, 76
Growth, xxv
Gubernaculum (guberno, I steer or guide)
testis, 1000
Gullet, 821
Gums, 780
Gustatory (gusto, I taste) cells, clvi
nerves, 606
Guttural (guttur, the throat) fossa, 59
Gyri (yvpos, a ring) of brain, 531
operti (covered convolutions), 532
Gyms fornicatus (arched convolution),
hippocampi (convolution of the hip-
pocampus), 533
HABENULA perforata (perforated strip),
763
tecta vel arcuata (covered or arched
strip), 763
Haemal (ot>o; blood) spine, 23
1110
INDEX.
Hsemapoietic (atpa, blood ; voieco, I make)
function of liver, li
Hsemapophysis (alpa, blood ; apophysis),
23
Hsematin (aina, blood), xxxiv
Hsematoglobulin, xxxiv
Haematoidin (hcematin ; dSos, shape),
_ xxxvi
Hsemin (alpa, blood), xxxvi
Haemorrhoidal (<u/*o, blood ; few, \ flow)
artery. See ARTERY
nerves. See NERVES
Hairs, ccviii
chemical nature of, cexv
cuticle of, ccviii
development of, ccxii
distribution of, ccxiv
ending of nerve-fibres in, civ
follicles of, ccix
growth of, ccxi
medulla or pith of, ccviii
muscular fibres of, ccxi
reproduction of, ccxiv
root of, ccix
stem of, ccviii
Halitus (breath) of blood, xliv
Hamstring muscles, 270
Hamular process of sphenoid bone,
41
Hamulus (dim. of hamus, a hook) of coch-
lea, 756
laehrymalis, 50
Hand, bones of, 86
compared with foot, 115
dissection of, 1065
fascia? of, 231
ligaments of, 142
muscles of, 225
nerves of, 649, 65 1
ossification of, 90, 93
vessels of, 391, 393, 397, 400
Harmonia (apfjLofa, I fit together), 119
Haunch, 93
Haversian canals, xci
spaces, xciii
Head, bones of, 29
dissection of, 1048
muscles of, 196
veins of, 455
of a bone, Ixxxviii
HEART, 297
apex of, 302
arteries of, 321, 338
atria of, 304
auricles of, 302, 303, 304
capacity of, 322
development of, 323
fibres of, 317
left, 311
right, 308
septum of, 309
position of, 315
auriculae or auricular appendages of,
304
bone of, 316
HEART— continued.
cavities of, clxv, 304
chordse tendinese of, 305, 306, 307,
310
columnse carnese of, 305 312
covering of, 300
development of, 323
dissection of, 1067
endocardium of, 304
external form of, 302
fibrous rings of, 316
structure of, 316
foetal, 323
foramina of. See Foramen, and
Foramina
form of, 302
fossa ovalis of, 309
furrow, auriculo-ventricular, 303
longitudinal, 303
lining membrane of, 304
lymphatics of, 497
muscular fibres of, cxxvi, 317
musculi papillares of, 305, 307, 310,
313
pectinati of, 304, 312
nerves of, 321
orifices of, aortic, 313
auriculo-ventricular, left, 312
right, 308
positions of, 315
pulmonary, 310
size of, 322
of venae cavse, 308
position of, in the chest, 297, 302,
313
relation to surrounding parts, 297
septum, auricular, 309
fibres of, 320
ventricular, 310
serous coat, external, 300
sinus, coronary, 310
venosus, 304
size of, 321
structure of, 316
valves of, auriculo-ventricular, 305
left, 313
right, 310
Eustachian, 309, 325
mitral or bicuspid, 313
sigmoid or semilunar, 307
left, 313
right, 310
Thebesian, 310
tricuspid, 310
veins of, 321, 482
ventricles, in general, 302, 305
fibres of, 318
septum of, 310
ventricle of, left, 312
capacity of, 322
walls of, 312
right, 310
capacity of, 322
walls of, 310
weight of, 321.
INDEX.
1111
Hearts, lymphatic, cxc
Heel, 107
Helicine (eAi£, a spiral) arteries, 958
Helicotrema (eA<£, a spiral ; rpy/jia, a hole),
Helix (eAj£, a spiral), 741
fossa of, 741
muscles of, 742
process of, 742
Hemispheres, cerebellar, 522
cerebral, 529
Hemisphere vesicle, 580
Hepatic (ji-rap, the liver) artery, 408, 867,
871
cells, 873
duct, 867
nerve, 701
vein, 474, 871
blood of, xliii
Hepato-cystic (^irap, the liver ; KV&TIS, a
bladder) ducts, 869
Hernia (epvos, a branch), congenital,
1025
femoral, anatomy of, 1031, 1080
coverings of, 1035
descent of, 1034
diagnosis of, 1035
operation on, 1036
infantile, 1026
inguinal, deep parts involved in,
1071
diagnosis of, 1029
direct or internal, 1027
in female, 1029
oblique or external, 1025
in female, 1026
operation for, 1030
parts concerned in, 1018
sac of, 1025
scrotal, 1025
surgical anatomy of parts concerned
in, 1018
umbilical, cause of, 862
ventro -inguinal, 1027
Hesselbach, triangle of, 1027, 1029
Hiatus (an opening, from hio, v. n., I
open) aorticus, 246
Fallopii, 38, 6 1
interosseus, 140
Highmore, antrum of, 46
Hilus (or hilum, the mark or scar on a
bean) of kidney, 927, 928
of lymphatic glands, clxxxvii
of spleen, 883
Hilus-stroma, cxxxvii
Hip-joint, bones of, 96, 100
dissection of, 1082
ligaments of, 151
movements of, 153
muscles of, 266
Hippocampi, fissure of, 533
gyrus (convolution of the hippo-
campus), 533
tsenia (band of the hippocampus),
544
Hippocampus (iWoKo/xTros, from l-mros, a
horse, and /CO^TTTW, I bend, a coiled
sea animal) major, 544, 581
minor, 544, 581
Hippuric (iinros, a horse; ovpov, urine)
acid, xl, 939
Histogenetic (la-ros, a tissue; yevvau), I
produce) molecules, xxiv
Histology (faros, a tissue ; \oyos, dis-
course), ii
Histolytic (/OTTOS, a tissue ; Avw, I dis-
solve) molecules, xxiv
Homologies of upper and lower limbs, 115
of vertebra?, 21
Homology (6^os, the same ; Ao7os, pro-
portion), 2
Homotypy (6>tos,the same ; TVTTOS, a type), 2
Horny substance of teeth, 792
Horse-shoe kidney, 927
Huguier, canal of, 745
Humerus (the shoulder), 78
compared with femur, 116
ossification of, 90
Humour, aqueous, 737
Hunter's canal, 294
Huxley's layer, ccxi
Hyaline (va\os, glass) cartilage, Ixxxi
coat of hair-follicle, ccx
Hyaloid (va\os, glass ; et'Sos, shape) mem-
brane, 731
Hydatids of Morgagni, 968
Hydrocele, coagulation of fluid of, xxxviii
Hymen (vfjunv, a membrane), 978
Hyoglossus (uoetSijs, hyoid bone ; yXwvaa,
tongue) muscle, 186
Hyoid (v, the letter upsilon; eiSos, shape)
bone, 52
development of, 66, 70, 71
muscles of, 183, 191
Hypochondriac (VTTO, under ; xovSP°s> car*
tilage) regions, 824
contents of, 826
Hypogastric (VTTO, under ; yaffT-qp, the
stomach) artery, 328, 420
nerve, 660
region, 824
contents of, 826
Hypoglossal (viro, under ; y\wffffa, the
tongue) nerve, 519, 587, 589, 626
Hypophysis (UTTO, under; <pua>, 1 grow)
cerebri, 539
Hypospadias (viro, under ; arrow, I draw
out), looi
Hypothenar (VTTO, under; Bevap, the palm)
eminence, 227
Hypoxanthin (viro, under ; £<w0oy, yellow),
xl, cxxviii
ILEO-C.ECA.L valve, 852
Ileo-colic artery, 410
valve, 852
Ileum (ei'Aeo>, I roll), 840. See INTESTINE,
small
position of, 824
1112
INDEX.
Iliae arteries. See ARTERY
fossa, 95
region, muscles of, 271
Iliacus (ilia, the flank) muscle, 271
Ilio-aponeufotic muscle, 273
llio-costalis muscle, 234
Ilio-femoral ligament, 152
llio-hypogastric nerve, 660
Ilio-inguinal nerve, 660
Ilio-lumbar artery, 429
ligament, 147
llio-pectineal line, 95
Ilio-psoas muscle, 271
Ilium (ilia, the flanks), 94
ossification of, no
Impressio coli on liver, 865
renalis on liver, 865
Incisor foramen, 44, 45
fissure, 69
teeth, 781
eruption of, 800, 803
Incisura (notch) of acetabulnm, 96
ethmoidalis, 33
intertragica, 741
semilunaris, 76
of sternum, 24
Incus (an anvil), 748
development of, 66
ligament of, 749
Indicator muscle, 224
Infantile hernia, 1026
Infracostal muscles, 243
Inframaxillary nerve, 615
Infraorbital artery, 357
canal, 46
foramen, 45
Infraspinatus muscle, 210
Infraspinous artery, 373
fossa, 74
Infundibula (funnels) of kidney, 928
Infundibuliform fascia, 965
Infundibulum of brain, 539
of ethmoid bone, 43
heart, 310
lungs, 900
Ingrassias, wings of, 40
Inguinal (inguen, the groin) canal, 963,
1023
hernia, 1025. See Hernia
Innominate artery. See ARTERY
bone, 93
ossification of, 1 10
Inosinic acid, cxxviii
Inosite, cxxxiv
Interaccessorii muscles, 238
Interarticular fibro-cartilages and liga-
ments. See the various joints
Interclavicular notch, 24
ligament, 134
Intercolumnar fascia, 965, 1020
Intercondyloid fossa, 102
Intercostal arteries. See ARTERY
muscles, 240, 241
nerves, 655
Inter-laminar plexus, 850
Interlobular branches of hepatic artery,
873
Intermaxillary bone, 70
Intennetatarsal ligaments, 165
Internodia (inter, between ; nodus, a
knot), 87
Interossei. See MUSCLES
Interosseous arteries. See ARTERY
ligament. See LIGAMENTS
Interpeduncular space, 536
Interspinales muscles, 238
Interspinous ligament, 124
Intertransversales muscles, 238
Intertransverse ligaments, 125
Intertrochanteric line, 101
Intertubular stroma of kidney, 938
substance of teeth, 787
Intervertebral discs, 12 1
foramina, 5
INTESTINE, large, 851
caecum, 852
colon, 853
development of, 86 1
dissection of, 1073
divisions of, 851
epithelium of, 856
follicles of, 856
glands of, 856
length and extent of, 851
lymphatics of, 858
mucous membrane of, 855, 858
muscular coat of, 854, 858
position of, 825
rectum, 856. See RECTUM
structure of, 854, 858
tubuli of, 856
valve of, 852
vessels and nerves of, 856, 858
INTESTINE, small, 838
absorbents of, 850
areolar coat of, 841
convolutions of, 840
crypts of, 845
development of, 86 1
dissection of, 1072
divisions of, 838
duodenum, 839
epithelium of, 844, 846
glands of, 845
agminated or Peyer's, 846
Brunner's, 849
crypts of Lieberkiihn, 845
solitary, 849
ileum, 840
jejunum, 840
lacteals of, 844, 847
length and extent of, 838
mesentery of, 838
mucous membrane of, 842
muscular coat of, 841
nerves of, 850
peristaltic movement of, 841
position of, 824
serous coat of, 841
structure of, 841
INDEX.
1113
INTESTINE, small— contin ued.
valves of, 842
vessels, 843, 849
villi of, 842
Intracartilaginous ossification, ciii, cvi
Intralobular veins, 870, 871
Intramembranous ossification, ciii
Involuntary muscles, cxxiv
Iris (Ipis, a rainbow), 718
blood-vessels of, 723, 726
nerves of, 724
pigmentary elements of, 719
pillars of, 716
structure of, 718
Iron in blood, xxxiv
Irritability, muscular, cxxix
duration after death, cxxx
Ischio-cavernosus muscle, 264
Ischio-rectal fossa, 269, 1043
region, 1037
Ischium (t(Tx»oj/, the hip), 96
ossification of, no, 112
Island of Eeil, 532, 555
I so tropic substance in muscle, cxx
Isthmus faucium, 90, 779
of thyroid body, 920, 921
Isthmus Vieussenii, 309
Ivory of teeth, 785
JACOB'S membrane, 726
Jaw, changes in during dentition, 804
lower, 51
development of, 70, 71
ligaments of, 132
muscles of, 181
upper, 44
development of, 69, 71
Jejunum (jejunus, empty), 840. See IN-
TESTINE, small
position of, 824
Joint, ankle, 158
clavicular, 134
crico-thyroid, 909
elbow, 140
foot, 1 60
hand, 142
hip, 151
jaw, lower, 132
knee, '53
occipito-vertebral, 125
pelvic, 147
radio-ulnar, 138
of ribs, 128
shoulder, 136
vertebral, 121
wrist, 142
Joints in general, 118
motions of bones in, 120
synovial membranes of, cxciii
Jugular eminence, 31
foramen, 59
fossa, 37
vein. See VEIN
KERATIN (Kfpas, horn), ccxiii
Kerato-cricoid \Kfpas, a horn ; cricoid,
cartilage) muscle, 915
Kerkring, valves of, 842
KIDNEYS, 926
adipose capsule of, 926
calyces or infundibula of, 928
coat of, fibrous, 928
corpuscles of, Malpighian, 929,
930
cortical substance of, 929
development of, 993
excretory duct of, 928
form of, 927
glomeruli of, 931
hilus or fissure of, 927, 928
horseshoe, 927
intertubular stroma of, 938
lymphatics of, 495, 938
medullary substance of, 929
nerves of, 938
papilla of, 928, 929
pelvis of, 928
position of, 926
primitive or primordial, 993
pyramids of, Ferrein's, 929
Malpighi's, 929
sinus of, 928
size of, 926
relative, in foetus, 994
structure of, 928
surfaces and borders of, 927
tubuli of, 929
convoluted, 930
looped, 930
origin and course of, 933
straight, 930
structure of, 930
varieties of, 927
vessels of, 935
distribution of, 931, 937
weight of, 926
Knee-joint, bones of, 103
dissection of, 1085
ligaments of, 153
movements of, 157
Knee-pan, 103
Kreatin (wpeos, flesh), cxxviii, cxxxiv
LABIA pudendi, 977
majora, 977
development of, 1001
minora, 977
Labial artery, 350
glands, 779
Labium tympanicum, 760, 761
vestibulare, 761
Labyrinth (hafrvpivQos, a maze, from its
complex structure), 753
development of, 768
membranous, 757
osseous, 753
lining membrane of, 757
vessels of, 767
1114
INDEX.
Lacerti of muscle, cxvi
Lachrymal apparatus, 709
artery, 360
"bone, 50
ossification of, 70, 71
canals, 709
gland, 709
nerve, 597
sac, 709
LACTEALS (lac, milk), 491
General Anatomy of, xlvii, clxxxvi
origin of, clxxxvii
plexuses of, in intestine, 846
relation to villi, 844
Lactiferous (lac, milk ; fero, I carry)
ducts, 1003
Lacuna, ccxxii
magna, 963
Lacunse in bone, xciv
formation of, ex
Lacunar origin of lymphatics, clxxxiii
Lambdoidal (A, the letter lambda ; flSos,
shape) suture, 54
Lamella, cribiform, 43
Lamellae of bone, xc, xcv
Lamina of a vertebra, 4
cinerea (grey layer), 539
cribrosa (a plate perforated like a
sieve) of sclerotic, 712
of temporal bone, 38
denticulate, of cochlea, 761
elastic, of cornea, 715
fusca, 716
reticularis, 765
spiral of cochlea, 755
spiralis membranacea, 760
spiralis ossea, 756
Lamina? or plates of vertebra, 4, 6, 8, 9
Laminated tubercle, 525
Lancisi, nerves of, 542
Lanugo (wool or down), ccxiii
LARYNX (\apvy£, the larynx), 905
cartilages of, 905
arytenoid, 907
cricoid, 906
cuneiform, 908
ossification of, 919
Santorini's, 908
structure of, 909
thyroid, 906
of Wrisberg, 908
development of, 919
dissection of, 1058
glands of, 913, 918
growth of, 919
interior of, 910
ligaments of, 909. See LIGAMENTS
mucous membrane of, 918
muscles of, 914
action of, 917
nerves of, 622, 919
pouches of, 913
ventricles or sinuses of, 913
vessels of, 348, 371, 919
vocal cords of, 912
Latissimus dorsi muscle, 200
Laxator tympani muscle, 750
Layer, columnar, of retina, 727
granular, of dentine, 789
internuclear of retina, 728
nervous of retina, 728
Leg, aponeurosis of, 294
articulations of, 158
bones of, 103, 105
dissection of, 1082, 1084
muscles of, 279, 282
nerves of, 683
Lemniscus (A^J/KT/COS, a band), 557
Lens (a lentil), crystalline, 733
capsule of, 733
changes in by age, 735
development of, 737
fibres of, 735
structure of, 734
suspensory ligament of, 736
Lenticular (dim. from lens) follicles of
stomach, 837
ganglion, 599
Leucin (Aeu/cos, white), xl, cxxxiv
Levator. See MUSCLES
Lex progresses, clxi
Lieberkiilm's crypts, 845
Lienculi (little spleens), 884
Life, application of the term, vii
Ligamenta arcuator, 243
lata, 986
subflava, Ixxvii, 123
suspensoria, 229
vaginalia, 213
LIGAMENTS (ligo, I bind), acromio clavi-
cular, 134
of ankle, annular, anterior, external,
and internal, 295
anterior, 160
dissection of, 1085
external and internal, 159
lateral, 159
posterior, 160
arytenoid, 909
astragalo-calcaneal, external, 161
iuterosseous, 160
posterior, 160
astragalo-scaphoid, 161
atlanto -axial, anterior and posterior,
128
of atlas, transverse, 125
of bladder, false, 945, 947
true, 945
anterior, 260, 952
lateral, 261
calcaneo- cuboid, dorsal or superioi',
162
internal or interosseous, 162
inferior, 162
short or deep-seated, 162
superior, 162
calcaneo-scaphoid, external, interos-
seous, or dorsal, 161
inferior, or plantar, 161
INDEX.
1115
LIGA MENTS — continued.
carpal, annular, anterior and pos-
terior, 144, 231
dissection of, 1066
dorsal, 142, 143
interosseoiis, 142, 143
lateral, 142
palmar, 142, 143
carpo-metacarpal, 144
central of spinal cord, 505
coccygeal, 147
of colon, 854
conoid, 135
coracoid, 136
coraco-acromial, 136
clavicular, 135
humeral, 137
costo- clavicular, 134
coracoid, 229
sternal, 130
transverse, 129
anterior or long, 130
middle or interosseous, 130
posterior, 129
vertebral, 128
xiphoid, 130
cotyloid, 132
crico-arytenoid, 910
thyroid, 909
crucial, 155
cruciform, 126
of cuboid bone, 162, 163
of cuneiform bones, 163
of elbow, 140
anterior. 141
dissection of, 1066
lateral, external and internal,
141
posterior, 141
of Fallopius, 249
of fingers and toes, transverse, 296
of foot, 1 60
dissection of, 1085
of forearm, 138
dissection of, 1066
gastro-phrenic, 829
Gimbernat's, 250, 1031
glenoid, 137
of hand, 142
dissection of, 1066
of hip-joint, accessory, 152
capsular, 152
cotyloid, 152
dissection of, 1082
ilio-femoral, 152
interarticular or round, 152
transverse, 152
hyo-epiglottic, 908
ilio-femoral, 152
lumbar, 147
of^ incus, 749
interclavicular, 134
interspinous, 124
intertransverse, 125
inteTrvertebral, 121, 147
LIGAMENTS — continued.
of knee-joint, 153
capsular, 156
crucial, 155
dissection of, 1085
lateral, external and internal,
154
posterior, 155
transverse, 156
of larynx, 909
of leg, 158
of liver, broad, 827, 865
coronary, 827, 865
falciform, 827, 865
round, 827, 865
suspensory, 827, 865
triangular, 827, 865
of lower jaw, 132
of lower limb, 151
of malleus, posterior, 750
suspensory, 749
metacarpal, dorsal, 145
interosseous, 145
palmar, 145
of thumb, 145
metacarpo phalangeal, 145
anterior, 145
lateral, 145
metatarsal, 165
transverse, 166
metatarso-phalangeal, 166
obturator, 150
occipito-atlantal, 128
axial, 128
odontoid, 126
middle, 127
orbicular, 138
of stapes, 749
of ovary, 986, 988
palpebfal, 707
of patella, 155
lateral, 156
of pelvis, 147, 1078
peritoneal, 826
peroneo-tibial, superior, 158
inferior, 159
transverse, 159
of phalanges, fingers, 146
toes, 1 66
of pinna of ear, 742
Poupart's, 249, 1031
pterygo-maxillary, 176
pubic, anterior, 149
inferior, 150
posterior, 149
superior, 149
pubo-prostatic, 952
radio- carpal, 142
radio-ulnar, 138
of ribs, 128
sacro-coccygeal, anterior and poste-
rior, 147
sacro-iliac, anterior, 148
oblique, 148
posterior, 147
1116
INDEX.
LIGAMENTS — contained.
sacro-sciatic, anterior, 148
posterior, 148
sacro-vertebral, 147
of scaphoid bone, 161, 163
of scapula, 136
scapulo- clavicular, 134
of shoulder-joint, 136
dissection of, 1064
capsular, 136
glenoid, 137
spiral, 761
of stapes, 749
stellate, 128
of sternum, 131
sterno-clavicular, 134
stylo-hyoid, 52, 133
stylo-maxillary, 133, 197
subpubic, 150
supraspinous, 124
suprascapular, 136
suspensory, crystalline lens, 731, 736
liver, 827, 865
malleus, 749
of odontoid process, 727
penis, 257, 955
talo-scaphoid, 161
tarsal, of eyelid, 707
of foot, 160
tarso-metatarsal, 165
temporo-maxillary, 132
terminal, of spinal cord, 502, 505
thyro-arytenoid, inferior and supe-
rior, 910
thyro-epiglottic, 908
thyro-hyoid, 909
tibio-fibular, inferior, 158
superior, 159
trapezoid, 135
of tympanum, 749
of upper limb, 134
of urethra, triangular, 260, 1040
of uterus, 985
anterior and posterior, 986
broad, 986
round, 986
vertebral, 122, 124
dissection of, 1069
of wrist, 142
yellow of spine, 123
Ligamentum arcuatum externum, 244
arcuatum internum, 244
breve, 218
colli costse, 130
cruciatum cruris, 295
denticulatum, 566
latum pulmonis, 894
mucosum, 157
nuchse, Ixxvi, 125
patella?, 155
pectinatum, 721
proprium anterius, 136
posterius, 136
rhomboides, 134
spirale, 764
LIGAMENTS — continued.
suspensorium (of bladder), 947
deutis (of the odontoid process),
127
teres of hip-joint, 152
teres uteri, 987
transversum cruris, 295
LIGATURE of the brachial artery, 1010
carotid, common, 1005
femoral, 1015
iliac, common, 1012
external, 1014
internal, 1014
subclavian, 1007
Ligula, 517
Limb, lower, articulations of, 151
bones of, 93
development of, no
dissection of, 1078
muscles of, 266
veins of, 475
upper, articulations of, 134
bones of, 74
development of, 88
dissection of, 1059
muscles of, 198
veins of, 465
Limbs, homologies of, 114
relation to segments of trunk, 1 1 7
Limbus lamina? spiralis, 761, 763
luteus of the retina, 726
Line of bone, Ixxxviii
curved of ilium, 94, 95
ilio-pectineal, 95, 96
iutertrochanteric, 101
occipital, curved, 30, 31
pectineal, 96
popliteal, 104
Linea alba, 255
aspera, 101
splendens, 567
Linese semilunares, 255
transverse, 255
Lines of enamel, 789
contour of dentine, 788
Lingual artery, 348, 812
Lingula, 42
Lips, 779
arteries of, 350
muscles of, 175
Liquor Cotunnii, 757
Morgagni, 733
sanguinis, xxvii, xxxii, xxxvii
seminis, 975
Lister's researches on movements in pig-
ment cells, xx
on coagulation of blood, xlvi, xlvii
Lithotomy, 1043
LIVEH, 862
accessory, 869
capillaries of, 873
cells of, 873
changes in, after birth, 880
chemical characters of, 863
coats of, 869
I.XDEX.
1117
LIVER — continued.
congestion of, 873
development of, 863, 879
dissection of, 1074
ducts of, 868
aberrant, 877
commencement of, 875
structure of, 877
excretory apparatus of, 867
fissures of, 864
foetal, peculiarities of, 879
fossse of, 864
hsemapoietic function of, li
ligaments of, 824, 865
lobes of, 864
lobules of, 870
lymphatics of, 493, 867
nerves of, 867
position of, 824, 865
size of, 862
specific gravity of, 863
structure of, 869
surfaces of, 863
varieties in the, 868
vessels of, 867
distribution of, 871
in the foetus, 880
weight of, 863
Lobe, bi ventral, 524
central of cerebellum, 525
of cerebrum, 535
curved, 536
frontal, 535
fronto-parietal, 536
maxillary, 65
occipital, 535, 536
occipito-temporal, 536
parietal, 535
quadrate, 524
slender, 524
subpeduncular, 524
temporo-sphenoidal, 535
Lobes of cerebellum, 524
of cerebrum, 529
Gratiolet's arrangement of, 535
liver, 864
lung, 895
prostate, 953
testis, 969
thymus gland, 923
thyroid body, 920
Lobule of ear, 741
of pneumo-gastriu nerve, 524
Lobules of liver, 870
of lungs, 898
Lobuli testis, 969
Lobulus caudatus, 864
quadratus, 864
Spigelii, 864
Locus niger, 556, 561
perforatus anticus, 531, 539
perforatus posterior, 536
Lower, tubercle of, 310
Luette vesicale (Fr., uvula of the bladder),
948
Lumbar arteries, 417
ganglia, 696
region, 417
contents of, 417
plexus, cxlvi
vertebrae, 6
Lumbricales (lumbricus, an earthworm)
muscles, 219, 287
LTJNGS, 894
air-cells of, 899
tubes of, 898
subdivision of, 900
capacity of, 896
capillaries of, 902
changes at birth in, 904
colour of, 897, 905
development of, 904
foetal, 904
form of, 894
lobes of, 895
lobules of, 898
lymphatics of, 496
nerves of, 903
roots of, 897
size and weight of, 895
specific gravity of, 897
structure of, 898
surfaces and borders of, 895
texture of, 897
vessels of, pulmonary, 898
bronchial, 903
Lunula (dim. of luna) of nails, ccvi
of valves of heart, 308
LYMPH (lympha, water), xlviii
of blood, or liquor sanguinis, xxvii
channels, clxxxiii, clxxxviii
chemical composition of, xlix
corpuscles, xlviii
formation of, 1
duct, right, 488
plasma of, xlviii
sinus, clxxxvii
LYMPHATIC system, General Anatomy of,
clxxxii
glands, xlvii, clxxxvi
structure of, clxxxvi
vessels of, clxxxviii
hearts, cxc
vessels, xlvii, clxxxii
afferent, clxxxvi, clxxxix
in areolar tissue, Ixxiii
of bones, cii
coats of, clxxxiv
development of, cxci
distribution of, clxxxii
efferent, clxxxvi, clxxxix
lacteal. See Lacteals
lacunar origin of, clxxxiii
of mucous membrane, cxoviii
of muscle, cxxiii
orifices of, clxxxv
origin of, clxxxii
plexiform, clxxxii
of serous membrane, cxcii
of skin, ccv
1118
INDEX.
LYMPHATIC vessels — continued.
structure of, clxxxiv
termination of, cxc
valves of, clxxxv
vessels of, clxxxiv
vital properties of, clxxxv
LYMPHATICS, Descriptive Anatomy of, 486
of the abdomen, 490, 491
back, 499
bladder, 495, 951
chest, 499
cranium, 499
face, 499
head and neck, 499
heart, 497
intercostal, 496
intestines, large, 858
kidneys, 495, 938
larynx, 919
limb, lower, 488, 490
upper, 497, 498
liver, 493
lungs, 496
03sophagus, 497
pancreas, 493
pelvis, 490
penis, 490, 959
pia mater, 564
prostate, 954
rectum, 493, 858
scrotum, 490, 967
spleen, 493, 887
sternum, 496
stomach, 493, 838
suprarenal capsules, 495, 941
testicle, 495, 975
thorax, 495
thymus gland, 497, 925
thyroid gland, 922
trunk, lower half, 488, 490
ureter, 495
uterus, 495, 987
vulva, 980
Lymphoid (lympha ; etSoy, shape) tissue,
cxcix, cc
Lyra, 547
MACULA germinativa (germinal spot), xv,
990
lutea, (yellow spot), 726
colour of, 730
Madder, effect of, on bone, cxiii
Malar (mala, the cheek) arch, 57
artery, 360
bone, 49
ossification of, 70, 71
foramina, 49, 56, 57
nerves, 600
process, 45
Malleolar (malleolus, the ankle) arteries,
449, 45°
Malleolus (dim. of malleus, a hammer ;
the ankle), external, 105
internal, 104
Malleus (a hammer), 748
ligaments of, 749, 750
ossification of, 66
Malpighian corpuscles of kidney, 929,
93°
of spleen, 887
layer of skin, Iv, ccii
pyramids of kidney, 929
Mammary (mamma, the breast) artery.
See ARTERY
glands, in female, 1002
in male, 1004
structure of, 1003
varieties of, 1004
vessels and nerves of, 1004
veins. See VEINS
Mantle of cerebral vesicle, 580
Manubrium (a handle) of malleus, 748
of sternum, 23, 24
Marrow of bone, c
spinal. See SPINAL CORD
Masseter (na<raao/j.ai, I chew) muscle, 181
Masseteric (masseter} artery, 356
fascia, 197
nerve, 605
Mastoid (IM<TTOS, a nipple ; efSos, form)
artery, 351
cells, 746
foramen, 37
process, 36
Mastoido-humeral muscle, 193
Matrix of cartilage, Ixxxi
intercellular, xxiii
of nails, ccvi
Maxillary (maxilla, a jaw) artery. See
ARTERY
bone, lower, 51
ossification of, 70, 71
upper, 44
ossification of, 69, 71
lobe, 65
nerves. See NERVES
sinus, 46, 64
vein, 457
Meatus (meo, I pass), Ixxxviii
auditory, external, 37, 743
in infant, 744
structure of, 744
vessels and nerves of, 744
internal, 38, 61
of nose, inferior, 63, 774
middle, 43, 63, 774
superior, 43, 63, 774
urinarius (urinary passage) in female,
978, 980
Meckel's cartilage, 66, 769
ganglion, 603
Median artery, 369, 391
basilic (/WtAtKos, royal) vein, 466,
467
cephalic (/ce^aArj, the head) vein,
466, 467
cutaneous vein, 466, 467
nerve, 649
vein, 467
INDEX.
1119
Mediastinal arteries, 374, 402
veins, 454
Mediastinum (medius, the middle ; sto, I
stand), 297, 893
posterior, dissection of, 1068
testis, 969
MEDULLA OBLONGATA, 513, 514
columns of, 514
course of, 518
development of, 577
fibres of, 518
fissures of, 514
grey matter of, 519
weight of, 571
Medulla ossium (marrow of bones), c
of hair, ccviii
of tongue, 8 1 1
Medulla spinalis. See SPINAL CORD
Medullary canal of bone, formation of,
cxi
sheath of nerve-fibre, cxxxvi
spaces, cix
substance of encephalon, 555
of kidney, 929
of lymphatic glands, cxxxvii
Medullated nerve-fibres, cxxxv
Meibomian glands, 707
Membrana basilaris, 760, 763
fusca, 711, 723
granulosa, 990
limitans, 728
nictitans, 706
propria, of mucous membranes,
cxcvii
pupillaris, 721, 739
sacciformis, 139
of secreting glands, ccxxi, ccxxiv
of skin, cciii
tectoria, 761, 767
tympani, 745
secondary, 746
vestibularis, 761
Membrane, arachnoid, 565
basement. See Basement membrane
of black pigment, 718
of Bruch, 717
choroid, 716
of Corti, 761
costo-coracoid, 229
crico- thyroid, 909
of Demours or Descemet, 715
fenestrated or perforated, clxix
germinal, 15
hyaloid, 731
Jacob's, 726
limitary, of mucous membrane,
cxcvii
limiting, of retina, 728
lining, of osseous labyrinth, 757
of tympanum, 751
Nasymth's, 791
ossification in, ciii
periodontal, 780
pituitary, 774
preformative, 797
Membrane — continued.
primary, of mucous membrane, cxcvii
pupillary, 721, 739
of Keissner, 761, 767
Sehneiderian, 774
thyro-hyoid, 909
MEMBRANES OF THE BRAIN AND SPINAL
CORD, 562
development of, 581
mucous, serous, &c. See Mucous
and SEROUS MEMBRANES, &c.
Membranous cochlea, 760
labyrinth, 757
semicircular canals, 758
tube of nerve-fibre, cxxxvi
vestibule, 757
Meningeal artery. See ARTERY
vein. See VEIN
Meninges (fvnvryl-, a membrane), 562
development of, 581
Menstruation, utenis during, 987
Mental (mentum, the chin) foramen, 51
nerve, 608
Mesencephalon (jueeros, middle ; fy/c60aAoj/,
the brain), 577
Mesenteric (pea-os, middle ; evrepov, intes-
tine) artery, 410. See ARTERY
glands, 491
plexus, 702
veins, 481
Mesentery (fxeo-os, middle ; tvrcpov, intes-
tine), 824, 826
development of, 859
Mesial (/xeo-oy, middle) plane, 2
plate in embryo, 859
Mesocsecum (jueaos, middle ; ccecum),
826, 830
Mesocephalon (^<ros, middle ; K^aXij, the
head), 521
Mesocolon (jteo-oy, middle ; KW\OV, the
colon), 826
sigmoid, 830
transverse, 829
Mesogastrium (/uco-oy, middle ; yaarr^p,
the stomach), 86 1
Mesorchium (peaos, middle ; opxis, a tes-
ticle), 965
Mesorectum (/icaos, middle ; rectum), 826,
830, 856
Metabolic (^eTajSoAXw, I change) force,
viii
Metacarpal artery, 391, 398
Metacarpus (pera, beyond ; Kapiros, the
wrist), 86
ligaments of, 145
ossification of, 90, 93
Metapophysis (/tera, beyond; apophysis),
22
Metatarsal artery, 450
Metatarsus (pera, behind; rapaos, the
instep), 109
ligaments of, 164
ossification of, in, 115
Metencephalon (A^TO, behind ; eyK€<J)a\oj>,
the brain), 577
1120
INDEX.
Midriff (Sax. midd, middle ; hrif, the
belly), 243
Milk-teeth, 784
Mitral (fjurpa, a mitre) valve, 317
Modiolus (the nave of a wheel), 755, 756
Molar (mola, a mill) glands, 780
teeth, 783
eruption of, permanent, 803
temporary, 800
Molecular (molecula, dim. of moles, a
mass) base of chyle, xlix
layer of retina, 728
theory of organisation, xxv
Molecules, histogenetic and histolytic,
xxiv
Moles carnea (fleshy mass), 287
Monoplasts (/JLOVOS, single ; TTAOTO-W, I
form), xv
Monro, foramen of, 546
Mons Veneris, 977
Morbid growths, relation to natural tis-
sues, xxvii
Morgagni, corpora or hydatids of, 968
Morphological (/u-optyr], -form; \oyos, dis-
course) anatomy, i
Morsus diaboli (devil's bite), 991
Motion, ciliary, lix
of protoplasm in cells, xix
Motions of bones in joints, 120
Motorial end-plates of nerves, clvi
stimuli, cxxx, clxii
Mouth, 779
muscles of, 175
Movements of ankle-joint, 160
clavicular, 136
of elbow, 141
foot, 1 66
hand, 146
hip, 152
knee, 157
lower jaw, 133
occipito-vertebral, 128
of pelvis, 150
radius on ulna, 140
ribs, 131
shoulder, 138
vertebra, 125
wrist and fingers, 146
Muco-albuminous (mucus ; albumen) sub-
stance in foetus, Ixxii
Mucous MEMBRANE, General Anatomy
of, cxcv
alveoli of, cc
attachment of, cxcvi
basement membrane of, cxcvii
connective tissue of, cxcviii
corium of, cxcvii
divisions of, cxcvi
epithelium of. See EPITHELIUM
fibro-vascular layer of, cxcviii
folds and valves of, cxcvi
gastro-pulmonary, cxcvi
genito-urinary, cxcvi
glands' of, cc. See GLANDS
lymphatics of, cxcviii
Mucous MEMBRANE— continued.
mammary, cxcvi
muscular tissue of, cxcix
nerves of, cci
papillae of, cxcix
physical properties of, cxcvii
regeneration of, cci,
secretion of, cci
structure of, cxcvii
vessels of, cxcviii
villi of, cxcix
Mucous membrane of intestine, large, 855
small, 842
lachrymal apparatus, 710
larynx, 918
nose, 774
oesophagus, 822
palate, 813
pharynx, 820
rectum, 858
seminal ducts, 974
vesicles, 974
stomach, 834
tongue, 805
trachea, 892
tympanum, 751
ureters, 943
urethra, female, 980
male, 960, 962
urinary bladder, 95 1
uterus, 985
vagina, 982
vas deferens, 972
vulva, 977, 978
Mucous tissue, Ixxvii
Mucus, cci
Miillerian duct, 996
fibres, 728
Multangular bones, 85
Multicuspidate (multus, many; cuspis, a
point) teeth, 783
Multifidus (multus, many ; findo, I cleave)
spinse muscle, 243
Multilocular, ccxxii
Mul ti polar ganglion-globules, cxl
Muscle-corpuscles, cxxi
juice, reaction of, cxxix
serum, cxxviii
MUSCLES, involuntary, cxv, cxxiv
voluntary, cxv
origin and insertion of, cxv
sheaths of, cxvi
MUSCLES, Descriptive Anatomy of, cxv
abdominal, 248
abductor brevis pollicis, 225
abductor digiti minimi (hand), 227
abductor digiti minimi (foot), 290
abductor indicis, 228
abductor longus pollicis, 223
abductor pollicis (hand), 225
abductor pollicis (foot), 289
accelerator urinse, 264
accessorii orbicularis, 175
accessorius ad ilio-costalem, 234
adductor brevis, 277
INDEX.
1121
MUSCLES — continued.
adductor gracilis, 276
longus, 276
magnus, 277
ossis metacarpi digiti minimi,
227
pollicis manus, 226
pollicis pedis, 290
anal, 261
auconeus, 215
anconeus brevis, 214
internus, 214
longus, 214
quartus, 215
anomalus, 174
antitragicus, 743
of the arm, 212
arytcenoideus obliquus, 917
aryteuoid, 917
aryteno-epiglottidean, 917
attollens auriculam, 171
attrahens auriculam, 171
auricular, 170
auricularis, superior, anterior, et
posterior, 171
azygos uvulae, 190
of back, 232
nerves of, 684
basio-glossus, 186
biceps flexor cruris, 270
flexor cubiti, 212
bi venter cervicis, 237
brachiceus internus, 214
brachialis anticus, 214
buccinator (trumpeter muscle), 176
bulbo-cavernosus, 264
caninus, 175
cerato-glossus, 186
cervicalis ascendens, 234
diondro-glossus, 186
ciliaris, of orbicularis palpebrarum,
171, 706
ciliary, of eye-ball, 721
circumflextis palati, 191
coccygeus, 263
cochlearis, 764
complexus, 237
compressor hemisphcerium bulbi, 264
compressor naris, 1 74
sacculi laryngis, 914
compressores vence dorsalis penis, 264
constrictor of pharynx, inferior, i8S
middle, 1 88
superior, 189
isthmi faucium, 190
urethrse, 265
coraco-brachialis, 212
corrugator supercilii, 173
cremaster, 251, 965, 1022
crico-arytenoid, lateral, 915
crico-arytenoid, posterior, 914
crico-thyroid, 914
crotaphite, 181
crureus, 276
cucullaris (like a hood), 200
Muse LES — continued.
deltoid, 208
depressor ulse nasi, 174
anguli oris, 176
labii inferioris, 178
detrusor uriiine, 949
diaphragm, 243. See DIAPHRAGM.
diaphragma oris, 184
digastric, 183
dilatator naris anterior, 1 74
naris posterior, 174
pupilla?., 719
of ear, 170, 742, 749
ejaculator seminis, 264
epicranial, 169
erector clitoridis, 266
penis, 264
spinae, 234
extensor brevis digitorum pedis, 282
carpi radialis brevior, 221
carpi radialis longior, 220
carpi ulnaris, 223
coccygis, 238
digiti minimi, 222
communis digitorum, 221
indicis, 224
longis digitorum pedis, 280
major pollicis, 223
minor pollicis, 223
ossis metacarpi pollicis, 223
primi internodii pollicis, 223
proprius pollicis, 280
secundi iuternodii pollicis, 223
of eyelids, 171
face, nerves of, 684
femoral, anterior, 273
internal, 276
posterior, 270
flexor accessorius, 287
brevis digiti minimi manus, 227
brevis digiti minimi pedis, 291
brevis digitorum pedis, 289
brevis pollicis manus, 226
brevis pollicis pedis, 286
carpi radialis, 216
carpi ulnaris, 217
digitorum profundus, 219
digitorum sublimis, 217
longus digitorum pedis, 286
longus pollicis manus, 220
longus pollicis pedis, 288
pertbrans digitorum manus, 219
perforans digitorum pedis, 286
perforatus digitorum manus, 217
perforatus digitorum pedis, 289
of foot, 279
of forearm, 215
frohtalis, 169
gastrocnemius, 283
gemellus inferior, 269
superior, 269
genio-glossus, 185
genio-hyo-glossus, 185
genio-hyoid, 185
genito-urinary, 263
4 D
1122
INDEX.
MUSCLES — continued.
gluteus maximus, 266
medius, 267
minimus, 268
gluteal, 266
gracilis, 276
of great toe, 289
Guthrie's, 265
hamstring, 270
of hand, 225
head, 169
hip, 266
helieis major, 742
minor, 742
Houston's, 264
hyo-glossus, 1 86
of hyoid bone, 183, 191
of iliac region, 271
iliacus, 271
ilio-apoueurotic, 273
ilio-costalis, 234
ilio-psoas, 271
indicator, 224
infracostal, 243
infraspinatus, 210
intercostal, external, 240
internal, 241
internus mallei, 749
interossei, of hand, 227
of foot, 291
interspinales, 238
intertransversales, 238
ischio-cavernosus, 264
of jaw, 181
kerato-cricoid, 915
of larynx, 914
nerves of, 684
latissimus dorsi, 200
laxator tympani (major and minor),
750
of leg, anterior, 279
external, 282
posterior, 282
levator anguli oris, 1 75
anguli scapulte, 203
ani, 262
glandulse thyroidese, 921
labii inferioris, 178
labii superioris, 1 75
labii superioris alseque nasi, 174
menti, 178
palati, 190
palpebrse, 173, 179, 705
proprius alse nasi anterior, 174
proprius alse nasi posterior, 174
prostatae, 263,^953
levatores costarum, 241
longiores costarum, 242
lingualis, 810
inferior, 810
superficialis, 810
of lips, 175
longissimus dorsi, 235
longus colli, 196
of lower limb, 266
Muse LES — continued.
of lower limb, nerves of, 686
lumbricales (worm-shaped muscles),
219, 287
masseter (masticating muscle), 181
mastoido-humeral, 193
of mouth, 175
multifidus spinae, 238
mylo-hyoid, 184
naso-labialis, 174
of neck, flexor, 183
of nose, 173
noto-glossus (VUTOS, a back ; muscle
of the upper surface or dorsum of
the tongue), 810
oblique, of abdomen, external, 248
internal, 250
of the ear, 743
of eye, action of, 501*
inferior, i8oj
superior, 179
obliquus capitis inferior, 239
superior, 239
obturator externus, 269
internus, 269
occipitalis, 169
occipito-frontalis, 169
omo-hyoid, 192
opponens digiti minimi, 227
pollicis, 225
orbicularis latus, 171
orbicularis oris, 175
palpebrarum, 171, 7°6
of orbit, 179
action of, 180, 501*
nerves of, 684
of palate, 187
nerves of, 684
palato-glossus, 190
palato-pharyngeus, 190
palmaris brevis, 225
longus, 217
pectineus, 276
pectoralis major, 203
minor, 206
of penis, 264
of perinseum, 261
peroneus brevis, 282
longus, 282
tertius, 281
perpendicularis externus of tongue,
811
of pharynx, 187
nerves of, 684
plantar, short, 289
plantaris, 285
platysma myoides, 1 78
popliteus, 285
pronator quadratus, 220
radii teres, 215
psoas magnus, 272
parvus, 273
pterygoid external, 182
internal, 181
pyramidalis abdominis, 255
INDEX
1123
MUSCLES — continued.
pyramidalis nasi, 174
pyriformis, 268
quadratus femoris, 269
lumborum, 255
menti, 178
quadriceps extensor cruris, 274
recti of eye, 179
rectus abdominis, 243
capitis anticus major, 196
capitis anticus minor, 196
capitis lateralis, 196
capitis posticus major, 239
capitis posticus minor, 239
femoris, 274
rectus sternalis, 243
retrahens auriculam, 171
rhomboideus major, 203
minor, 202
of ribs, 240
risorius (laughing muscle), 176
rotatores spinae, 238
sacci lachrymalis, 173
sacro-coccygeus posticus, 238
sacro-luinbalis, 234
salpingo-pharyngeus, 189
Santorini's, 176
sartorius (tailor's muscle), 273
scalenus anticus, 193
medius, 195
posticus, 195
scapular, 208
semimembranosus, 271
semispinalis colli, 237
dorsi, 238
semitendinosus, 271
serratus raagnus, 207
posticus inferior, 233
posticus superior, 233
of shoulder, 208
soleus (muscle like a sole), 284
sphincter ani, external, 262, 265
internal, 261
oris, 175
of pupil, 719
vaginae, 266
sphincter vesicce, 949
spinalis cervicis, 238
dorsi, 235
splenius, 234
capitis, 234
colli, 234
stapedius, 750
sternalis bruiorum, 243
sterno-cleido-mastoid, 193
sterno-hyoid, 191
sterno- thyroid, 191
stylo-glossus, 1 86
stylo-hyoid, 184
stylo-hyoideus alter, 184
stylo-pharyngeus, 189
subanconeus, 215
subclavius, 206
subcostal, 243
subcrureus, 276
MUSCLES— continued.
submaxillary, 183
subscapularis, 208
supinator radii brevis, 223
longus, 220
supraspinatus, 208
temporal, 181
tensor palati, 191
tarsi, 173
tympani, 749
vaginae femoris, 273
teres major, 211
minor, 211
of thigh, 266
thorax, 240
nerves of, 685
thyro-arytenoid, 916
thyro-epiglottideau, 917
thyro-hyoid, 192
tibialis anticus, 279
posticus, 288
of tongue, extrinsic, 185
intrinsic, 810
trachelo-mastoid, 235
tragicus, 743
transversalis abdominis, 253
cervicis, 235
transversus auriculae, 743
pedis, 290
perinaei, 264, 265
trapezius, 200
triangularis oris, 176
sberni, 243
triceps extensor cubiti, 214
trochlearis (trochlea, a pulley), 179
of tympanum, 749
upper limb, 198
nerves of, 685
of urethra, 264
vastus externus, 275
internus, 276
Wilson's, 265
zygomaticus major, 176
minor, 176
Muscular contractility or irritability,
cxxix
duration of, after death, cxxx
stimuli of, cxxx
current, cxxix
rigidity, cxxxi
sense, cxxix
MUSCULAR TISSUE, General Anatomy of,
cxv
blood-vessels of, cxxiii
chemical composition of, cxxviii
cleavage into disks, cxx
connection with tendons, cxxi
corpuscles of, cxxi
cross stripes of, cxvii, cxix
development of, cxxvi
fasciculi of, cxvi, cxvii
fibres of, striped, cxvii
branched, cxxi
length and ending of, cxxi
unstriped, cxxiv
4 D 2
1124
INDEX.
MUSCULAR TISSUE— continued.
fibrils of, cxviii
growth of, cxxvii
interstitial, granules of, cxx
involuntary, cxxiv
lacerti of, cxvi
lymphatics of, cxxiii
my ol em ma of, cxviii
nerves of, cxxiv
terminations of in, clvi
nuclei of, cxxi
physical properties of, cxxix
plain or unstriped, cxxiv
regeneration of, cxxviii
sarcolemma of, cxviii
sarcous elements of, cxix
sensibility of, cxxix
sheath of, cxvi
vital properties of, cxxix
voluntary, or striped, cxv
Muscular tissue, of arteries, clxx
creraasteric, 965
of choroid, 721
dartos, 964
Fallopian tubes, 992
hair-follicles, ccxi
heart, cxxvi, 316
intestine, large, 853
small, 841
iris, 719
larynx, 914
lymphatics, clxxxiv
mammary glands, 1004
mucous membrane, cxcix
nipples, 1 002
oesophagus, 821
pharynx, 820
prostate, 954
rectum, 858
seminal ducts, 974
vesicles, 974
skin, cciii
stomach, 832
sweat-ducts, ccxvi
tongue, 809
trachea, 891
urinary bladder, 948
uterus, 985
vagina, 982
vas deferens, 972
veins, clxxiii
Musculi papillares of heart, 305, 307
left ventricle, 313
right ventricle, 308
pectinati of heart, 304
left auricle, 312
right auricle, 308
Musculo-cutaneous nerves, 648, 652, 680
Musculo-intestinal layer in embryo, 859
Musculo-phrenic (musculus, muscle ;
<t>pi]v, the diaphragm) artery, 375
Myentericus (/xus, a muscle; evrcpov, an
intestine) plexus, 851
Mylo-hyoid (nv\-rj, a mill, the jaw ;
hyoid bone) artery, 356
Mylo-hyoid groove, 52
nerve, 606
ridge, 51
Myoides (pvs, a muscle ; et'Sos, shape).
See PLATYSMA
Myolemma (MVS, a muscle ; Ae/x/ia, a
husk, or rind), cxviii
Myology (/«/s, a muscle ; \oyos, dis-
course), 167
Myosin (/tus, a muscle), cxxviii
Myotome (nvs, a muscle ; re/ij/w, I di-
vide), i
Myrtiform (nvprov, a myrtle-berry ; for-
ma, shape) fossa, 45
NAILS, ccvi
development of, ccviii
growth of, ccvii
matrix of, ccvi
reproduction of, ccviii
structure of, ccvii
Nares (nostrils), anterior, 6r
mucous membrane of, 775
posterior, 59
septum of, 6 1
Nasal (nasus, the nose) bone, 49
ossification of, 70, 71
cartilages, 771
duct, 709, 710
fossae, or cavities, 61, 773
mucous membrane of, 774
openings into, 64, 774
walls of, 63
Nasmyth's membrane, 791
Nates (buttocks) in cerebrum, 554 '
National differences in skull, 72
Navicular (navicula, a small ship or
boat) bone of foot, 108
of hand, 84
Neck, dissection of, 1052, 1053
fasciae of, 196
muscles of, 193, 234 — 240
veins of, 455
Negro, cause of colour in skin of, Ixiv
NERVES, CEREBRO-SPINAL, General Ana-
tomy of, cxliv
afferent, cxxxii
branching and conjunction of, cxlv
cellular sheath of, cxliv
communication with sympathetic,
clix
compound, clxiii
connection with cells, cxlviii
nervous centre, clxxxviii
ganglia, clxxxiii
grey matter, cxlvii
development of, cxliii
differences of, clvii
division of, cxlix
efferent, cxxxii
fibres of, cxlv
functions of, ix, clxii
funiculi of, cxliv, cxlviii
ganglia at roots of, cxlix
INDEX;
1125
NERVES, CEREBRO-SPINAL— continued.
motor, cxliii
moto- sensory, clxiii
nerves of, cxlvi
neurilemma of, cxliv
origins of, cxlvii, 583, 511
apparent, cxlvii
real or deep, cxlvii
peculiarities of, cxlix
perineurium of, cxliv
plexuses of, cxlvi
course of fibres in, cxlvi
regeneration and reunion of, clxv
relation of sympathetic to, clix
roots of, cxlvi
sensory, clxiii
terminations of, cl
sheath of, cxlv
simple, clxiii
structure of, cxliv
terminations of, cxlix
in end-bulbs, cli
epithelium, clvi
glands, clvi
hair-follicles, civ
muscle, clvi
networks or terminal plex-
uses, cl
nose, civ
organs of special sense, civ
Pacinian bodies, clii
teeth, civ
touch-bodies, cli
vessels of, cxlv
vital properties of, clxii
NERVES, SYMPATHETIC, General Ana-
tomy of, clviii
fibres of, clviii
parts of, clviii
relation to cerebro- spinal nerves,
clix
relation to roots of spinal nerves,
clxi
structure of, clviii
NERVES, Descriptive Anatomy of, 582
abdominal of ilio-hypogastric, 660
abducent, 586, 589, 610
accessory, spinal, 625
obturator, 663
acromial, 640
of arachnoid, 566
of arm, 683
articular of shoulder-joint, 644, 646
of elbow-joint, 649
hip-joint, 662, 664, 675
knee, 663, 665, 676, 679
temporo-maxillary joint, 606
wrist, 649
auditory, 587, 589, 615, 758, 763
auricular, of auriculo-temporal, 606
great, 638
posterior, 612
of pneumogastric, 621
of small occipital, 638
auriculo-temporal, 606
NERVES — contin ued.
axillary, 645
buccal, 606
of facial, 614
of buttock, 683.
cardiac, lower, 693
middle, or deep, 692
of pneumogastric, 623
upper, 690
carotid of petrous ganglion, 617
of Vidian, 605
cavernous of penis, 703
cerebro-spinal, 582
cervical, divisions of, anterior, 636
posterior, 633
second, 636
superficial, 638
cervico-faeial, 613
chorda tympani, 611
ciliary, long, 599
short, 600
circumflex of arm, 645
coccygeal, divisions of, anterior, 668
posterior, 635
of Cotunnius, .604
cranial, 582
crural, anterior, 664
internal, 662
cutaneous, of head, 682
of lower limb, 683
trunk, 682
upper limb, 683
abdominal, 657
external, of arm, 648
musculo-spiral, 653
internal, of arm, 646
musculo-spiral, 652
peroneal, 680
of thigh, 665
lateral, of last dorsal, 658
middle, of thigh, 665
of obturator, 662
.thoracic, anterior, 657
lateral, 657
dental, anterior, 60 1
inferior, 608
posterior, 60 1
descendens noni, 626
diaphragmatic, 640
digastric, 613
digital, in foot, .578, 679, 681
in hand, 649, 651, 653
dorsal, divisions of, anterior, 655
posterior, 624
first, 655
of foot, 68 1, 683
hand, 649, 653, 683
last, 658
of penis, 671
dorsi-lumbar, 658
of dura mater, 564
facial, 587, 589, 610
of femoral artery, 664
frontal, 597
gastric, 623 •
1126
INDEX.
NERVES — continued.
genito-crural, 660
glosso-pharyngeal, 519, 587, 589, 615
gluteal, inferior, 673
superior, 667
gustatory, 606
haemorrhoidal, inferior, 672, 703
superior, 703
hepatic, 701
hypogastric, 660
hypoglossal, 519, 587, 589, 626
iliac, 660
ilio-hypogastric, 660
inguinal, 660
incisor, 608
infra-maxillary, 615
orbital, 602
of facial, 613
trochlear, 599
intercostal, first, 655
lower or abdominal, 657
upper or pectoral, 655
intercosto-humeral, 657:
interosseous anterior, 651
posterior, 654
Jacobson's, 617
labial, 606
lachrymal, 597
of Lancisi, 542
laryngeal, 622
of leg, 683
lingual, of fifth, 608
glosso-pharyngeal, 618
of lower limb, 683, 686
lumbar, divisions of, posterior, 634
anterior. 658
fifth, 667
lum bo- sacral, 669
malar, of facial, 613
of orbital, 600
masseteric, 605
mastoid, 638
maxillary, inferior, 596, 605
superior, 596, 600
median, 649
mental, 608
motor of eye, common, 586, 589, 593
external, 586, 589
musculo- cutaneous of arm, 648
leg, 680
spiral, 652
mylo-hyoid, 606
nasal, 598
upper, 603
of Vidian nerve, 604
naso-palatine, 604
obturator, 662
accessory, 663
occipital (of facial), 612
great, 634
small, 638
oculo-nasal, 598
cesophageal, 623
olfactory, 583, 589, 592
ophthalmic, 596, 597
NERVES — continued.
optic, 580, 589, 592
orbital, 600
ovarian, 704
palatine, anterior or larger, 603
external, 603
posterior or smaller, 603
palmar, cutaneous, 649, 651, 683
palpebral, 543, 550
parotid, 606
pathetic, 586, 589, 594
of penis, 683
of perinseum, 683
perineal, 670
peroneal, 679, 680
communicating, 680
petrosal, superficial, large, 605
external, 611
small, 617
pharyngeal of pneumo-gastric, 621
of glosso-pharyngeal, 617
of spheno-palatine ganglion, 605
of sympathetic, 690
phrenic, 640
of pia mater, 564
plantar, external, 679
internal, 677
pneumo-gastric, 519, 587, 589, 618
lobule of, 524
popliteal, external, 679
internal, 676
portio dura, 587, 610
mollis, 587, 615
pterygoid, external, 606
internal, 606
pudendal, inferior, 675
pudic, 670
pulmonary, of pneumo-gastric, 623
radial, 653
recurrent laryngeal, 622
renal, 701
respiratory, external, 644
sacral, divisions of, anterior, 668
posterior, 635
fifth, 668
fourth, 668
saphenous, long, or internal, 666
short, or external, 677
sciatic, great, 675
small, 673
scrotal, long, 670
spermatic, external, 66 1
spheno-palatine, 603
spinal, 628. See SPINAL NERVES.
accessory, 519, 587, 589, 625
splanchnic, great, 695
small, 696
smallest, 696
sternal, 640
stylo-hyoid, 613
suboccipitaf, 632, 636
subscapular, 645
supra-clavicular, 639
maxillary, 615
orbital, 598
INDEX.
1127
NERVES— continued.
supra-scapular, 644
trochlear, 597
temporal, of auriculo-temporal, 606
deep, 605
of facial, 613
of temporo-malar, 600
temporo-facial, 613
malar, 600
of thigh, 683
thoracic, anterior, 645
posterior, 644
thyroid, 692
tibial, anterior, 682
posterior, 677
tonsillitic, 618
trifacial or trigeminal, 586, 589,
595
trochlear, 586, 589, 594
of trunk, 682, 684
tympanic, 617
of tympanum, 54
ulnar, 648
collateral, 652
of upper limb, 683, 685
of uterus, 704
vaginal, 704
of vas deferens, 703
vesiculae seminales, 703
vestibular, 66, 67
Vidian, 604, 690
of Wrisberg, 646
NERVES, SYMPATHETIC, descriptive
Anatomy of, 686
ganglia of. See GANGLION
gangliated cords of, 686
cervical part, 688
lumbar part, 696
sacral part, 696
thoracic part, 693
plexuses of, 698. See PLEXUSES
NERVES of areolar tissue, Ixxiv
of arteries, clxxi
auditory canal, 744
bone, cii
choroid coat of eye, 724
in cochlea, 763
of conjunctiva, 708
cornea, 716
coverings of testis and cord,
967
Fallopian tubes, 992
fibrous tissue, Ixxvi
heart, 321
intestine, small, 850
large, 856
iris, 724
kidney, 938
larynx, 919
liver, 867
lungs, 903
mammary gland, 1004
mucous membrane, cci
muscle, cxxiv
nose, 776
NERVES — continued.
of ovaries, 992
pancreas, 883
parotid gland, 816
penis, 959
pinna, 743
pleura, 894
prostate gland, 954
rectum, 858
secreting glands, ccxxv
in semicircular canal, 758
of serous membranes, cxciii
spleen, 887
stomach, 837
subliugual gland, 818
submaxillary gland, 817
suprarenal bodies, 941
teeth, 805
testis, 975
thymus gland, 925
thyroid body, 922
tongue, 812
tonsils, 814
trachea, 892
tympanum, 752, 753
ureters, 943
urethra, female, 980
urinary bladder, 95 1
uterus, 987
vagina, 982
veins, clxxiv
vulva, 980
NERVE-CELI s, or vesicles, cxxxix
of cerebellum, 528
cerebro-spinal centre, cxli
cerebrum, 560, 561
development of, clxiv
of ganglia, cxlii
olfactory, civ
of retina, 728
spinal cord, 510
varieties of, cxl
Nerve-corpuscles, genital, cli
Nerve-eminence, clvii
NERVE-FIBRES, cxxxv
afferent, cxxxii
axis of, cxxxvii
of cerebro-spinal nerves, cxliv
gelatinous or grey, cxxxviii
distribution in different nerves,
clvii
in terminations of nerves, cxlix
cl, cli, civ, clvi
in sympathetic nerve, clviii
medullated, cxxxv
nou-medullated, cxxxv, cxxxviii
white, appearance of, cxxxv
axis-cylinder of, cxxxvii
in cerebellum, 529
in cerebro-spinal nerves, cxliv
in cerebrum, 555
connection with grey matter,
cxlvii
ganglion-cells, cxlii
development of, clxiv
1128
INDEX.
NERVE-FIBRES — <
white, distribution in different
nerves, clvii
efferent, clxii
in ganglia, cxlii
looped, cxlvi
in medulla oblongata, 518
medullary sheath of, cxxxvi
membranous tube of, cxxxvi
in plexuses, cxlvi
in pons Varolii, 521
primitive band of, cxxxvi
sheath of, cxxxvi
of retina, 728
roots of spinal nerves, 511
spinal cord, 509
in sympathetic nerve, clviii
terminations of. See NERVES,
CEREBRO-SPINAL, termina-
tions of
varicose, cxxxvii
white substance of, cxxxvi
Nervi molles, 692
nervorum (nerves of nerves), clxvi
NERVOUS SUBSTANCE, cxxxiii
cells, corpuscles, or vesicles of. Sec
NERVE-CELLS
of cerebellum, 527
microscopic structure, 528
of cerebro-spinal nerves. See
NERVES, CEREBRO-SPINAL
of cerebrum, grey, 559
white, 555
chemical composition of, cxxxiii
fibres of. See NERVE-FIBRES
ganglia of. See GANGLIA
of medulla oblongata, grey, 519
white, 518
of retina, 726
of spinal cord, grey, 509
white, 509
structural elements of, cxxxiv
of sympathetic, clviii
NERVOUS SYSTEM, General Anatomy of,
cxxxi
cerebro-spinal centre of, cxxxii
nerves of, clxxxv
divisions or parts of, cxxxii
functions of, cxxxi
ganglia of, cxxxii
sympathetic portion of, clviii
vital properties of, clxii
NERVOUS SYSTEM, Descriptive Anatomy
of, 501
cerebro-spinal axis, 501
cranial nerves, 582
spinal nerves, 628
sympathetic nerves, 686
Nervus abducens, 586, 610
cardiacus magnus, 692
cardiacus profundus, 692
cardiacus superficialis, 690
cruralis interims, 676
ischiadicus, 675
ischiadicus minor, 673
Nervus —continued.
motor oculi externus, 586
motorius oculi, 593
oculo-nasalis, 598
patheticus, 586, 594
perforans Casserii, 648
popliteus intern us, 676
renalis posterior, 696
splanchnicus supremus, 696
tibialis posterior, 676
trigeminus, 586, 595
trochlearis, 586, 594
vagus (wandering nerve), 587, 618
Neural (vevpov, a nerve) cavity, 3
spines of vertebrae, 22
Neurapophysis (vevpov, a nerve ; apophy-
sis), 22
Neurilemma (vevpov, a nerve ; Ae/xjuo, a
peel or skin), cxliv
peculiarities of, cxlix
of spinal cord, 564
Neuroglia (vevpov, a nerve ; yXia, glue),
cxli, 543
Neurology (vevpov, a nerve ; Xoyos, dis-
course), 501
Neurotonic (vevpov, a nerve ; rep.v<a, I
cut), i
Nipple, 1 002
Nitrogenous and non-nitrogenous sub-
stances, v, vi
Nodule (nodulus, from nodus, a knot)
of cerebellum, 525
Nodulus Arantii, 308
Nodus encephali, 521
Norm a verticalis (vertical rule), 73
NOSE, 771
alse of, 772
cartilages of, 771
cavities of, 61, 773
constituent parts of, 771
development of, 778
fossae of, 61, 773
glands of, 775
meatus of, 43
mucous membrane of, 774
muscles of, 173
nerves of, 599, 603, 604, 776
olfactory region of, 776
septum of, 61, 772
skin of, 771
vessels of, 350, 356, 361, 362, 456,
464, 778
Notch, of acetabulurn, 96
iuterclavicular, 24
jugular, 31
sacro-sciatic, great and small, 96
scapular, 76
sigmoid, 52
supraorbital, 34
suprascapular, 76
Notches of vertebrae, 4
Notochord (voros, the back ; x°P$ai a
string or chord), 16
Notoglossus (VUTOS, a back ;
a tongue), muscle, 810
INDEX.
1129
Nuck, canal of, 965, 987
congenital hernia in, 1026
Nuclear (nucleus] fibres, Ixxi
layer of retina, 727
Nuclei (nucleus, a kernel) of blood- cor-
puscles, xxix, li
of cartilage-cells, Ixxxi
of colourless blood- corpuscles, xxxii
of connective tissue-corpuscles, Ixxiii
division of, xvi
of epithelial cells, liii
of fat cells, Ixiii
free, xv
of grey matter in medulla oblon-
gata, 519
multiplication of, xviii
in muscle, cxxi, cxxiv
of ossification, cxiv
part of, in nutrition, xxiii
of pigment-cells, Ixiv
Nucleolus (dim. of nucleus), xiii
Nucleus (kernel) of cells, xiii
olivary, 515
tseniseformis (tape -shaped nucleus),
56i
Nutrition of textures, xxiv
relation to secretion, ccxix
Nymphse, 977
development of, 1001
OBTURATOR (oUuro, I stop up) artery, 423
fascia, 261
foramen, 93, 96
ligament or membrane, 150
muscles, 269
nerve, 662
accessory, 663
Occipital (occiput, the back of the head),
artery, 351
bone, 29
ossification of, 67, 70
fissure, 536
foramen, 29, 61
fossae, 31
nerves. See NERVES
protuberances, 30, 31
ridge, 30
sinus, 463, 464
Occipito-atlantal ligament, 128
Occipito- axial ligament, 128
Occipito-frontal aponeurosis, 169
Occipito-frontalis muscle, 169
Occipito-mastoid suture, 55
Occipito-parietal suture, 54
Odontoid (oSovs, gen. oSovros, a tooth ;
et'Sos, shape) ligament, 126
process of the axis, 9, 21
Odoriferous matters in blood, xli
CEsophageal arteries. See ARTERY
glands, 823
nerves, 623
plexus, 695
(Esophagus (olu or otVcw, obs. = </>ep&>, I
bear; Qaytiv, to eat), 821
coats of, 821
(Esophagus, development of, 860
dilatations of, 823
foramen for, in diaphragm, 246
Olecranon (u\€inr}, the elbow ; Kpavos, a
helmet), 82
Oleiu (oleum, oil), Ixvii, cxxxiv
Olfactory bulb, 584
cells, civ, 776
nerve. See NERVES
membranes of, cxlix
Olivary (oliva, an olive) bodies, 515
^ development of, 577
fasciculus, 519
nucleus, 521
Omenta, 824, 826
Omentum (the caul) gastro-colic, 829
gastro- hepatic, 827
gastro splenic, 829
great, 829
sac of, 827
small, 827
Omo-hyoid (w^os, the shoulder; tiyoid,
bone) muscle, 192
Omphalo-enteric (o^a\os, navel ; Ivrepov,
intestine) canal, 859
Opercula (coverings, or lids) of dental
follicles, 794, 80 1
Ophthalmic (6<j>0aA^os, an eye) artery. See
ARTERY
ganglion, 599
nerve, 597
vein, 464
Opposition, 120
Optic nerve, 592. See NERVES
fibres of, clvii
membranes of, clxix
tract, 584
Om serrata (serrated border), 725
Orbicular bone, 749
ligament, 138
Orbicularis muscles. See MUSCLES
Orbital arch, 34
foramina, 34, 57
Orbits (orbita, a circle), 56
dissection of, 1056
muscles of, 179
nerves passing into, 594
Organ of Corti, 760, 761
structure of, 764
enamel, 797
of Giraldes, 973, 1001
of Rosenmiiller, 992
Organic systems of Bichat, iii
Organizing force, vii
Organon adamantinae, 797
Organs and textures, i
ORGANS of circulation, 297
development of, 323
of digestion, 779, 823
generation, female, 977
male, 952
development of, 995
mastication and deglutition, 779
respiration, 888
development of, 904
1130
INDEX.
ORGANS — contin ued.
of senses, 705
urinary, 926
development of, 992
voice, 905
Orthognathous (opflos, upright ; yvaQos, a
jaw) skulls, 73
Os calcis, 107
development of, in, 115
capitatum, 85
coxte (the bone of the hip), 693
lenticulare, 749
linguae, 52
magnum, 85
development of, 93
multangulum majus, 85
mUltangulum minus, 85
orbiculare, 749
pectinis, 95
pectoris, 23
planum, 43
pubis, 95
rotundum, 85
tincse (tench's mouth), 983
unguis, 50
uteri externum, 983
uteri internum, 984
xiphoides, 23
Ossa triquetra (triangular bones), 85
Ossa "Wormiana, 85
Ossicula auditus, 748
development of, 66
Ossification, cii
in cartilage, cvi
of cranial bones, 67
intracartilaginous, ciii, cvi
intramembranous, ciii
of lower limb, no
nuclei of, cxiv
of ribs and sternum, 28
of upper limb, 89
of vertebrae, 18
Ossified cartilage, xcix
Osteoblasts (barsov, a bone ; &\a<rTos, a
germ), cv
Osteodentine (oo-rfov, a bone ; dens, a
tooth), 792
Osteogen (oareov, a bone ; ycvvaca, I pro-
duce), cv, cix
Osteology (oa-reov, a bone ; \oyos, dis-
course), 2
Ostium abdorninale of Fallopian tube, 991
uterinum of Fallopian tube, 992
uteri, 984
Otic (ovs, gen. WTOS, the ear) ganglion,
608, 1057
Otoconia (ovy, gen. WTOS, an ear ; KOVIS,
dust), 757
Otoliths (ovs, gen. WTOS, an ear ; Aiflos, a
stone), 757
Ovarian artery. See ARTERY
nerve, 704
OVARIES (ovum, an egg), 988
development of, 995
Graafiau vesicles of, 989
OVARIES — continued.
ligaments of, 986
nerves of, 704, 992
situation of, 825
structure of, 988
vessels of, 992
Ovicapsule, 990
Oviducts, 991
Ovula Nabothi, 985
Ovum, 989
development of, 990
production of cells in, xv, xvii
structure of, 990
Owen's nomenclature of vertebral ele-
ments, 22
PACCHIONI glandulse, 567
Pacinian bodies, ciii
discovery of, ciii
distribution of, cliii
end of nerve-fibres in, clvi
function of, civ
in skin, ccvi
structure of, cliii
Palate, 813
bone, 46
ossification of, 70, 71
dissection of, 1058
hard, 44, 46, 813
muscles of, 187
soft, 189, 813
Palatine arteries. See ARTERY
canal, 45, 47
foramen, 45, 47
glands, 813
nerves. See NERYES
Palato-glossus muscle, 190
Palato-pharyngeus muscle, 190
Palmse plicatse, 984
Palmar arches, 393, 400
ligaments, 143
Palmaris muscles, 217, 225
Palpebrse (palpebra, an eyelid), 705
Palpebral artery, 362
Pampiniform (pampinus, a tendril ;
forma, shape) plexus, 975
Pancreas (TTCW, all ; /cpeos, flesh), 881
development of, 86 1, 883
dissection of, 1073
duct of, 883
head and tail of, 88 1
lesser, 88 1
position of, 826, 881
secretion of, 883
structure of, 882
varieties of, 883
vessels and nerves of, 883
weight of, 882
Pancreatic artery, 409
duct, 882
juice, 883
plexus, 702
Pancreatico-duodenal arteries, 408, 410
Pancreatin, 883
INDEX.
1131
Panniculus adiposus, Ixv, cciii, 168
camosus, 168, 179
Papilla lachry mails, 705, 709
Papillae of conjunctiva, 708
dental, 793
of hair-follicles, ccxi
kidney, 928, 929
mucous membrane, cxcix
O3sophageal, 823
of skin, cciv
of tongue, 806
circumvallate or large, 806
conical, 807
filiform, 807
fungiform or middle-sized, 807
structure of, 808
Papillary stage of dentition, 793
Par trigemiuum, 586
vagum, 587
Parapophysis (vapa, beside ; apophysis),
22
Parenchyma (irapryxvtj-a> interstitial in-
fusion) of glands, ccxxv
of liver, reaction of, 863
Parenchymal tissue, Ixx
Parietal bone, 32
ossification of, 67, 70
suture, 55
Parieto-mastoid suture, 55
PAROTID GLAND (TTO/JO, near ; ovs, gen.
UTOS, the ear), 814
accessory, 815
duct of, 816
structure of, c 816
vessels and nerves of, 816
Parotid fascia, 197
Parovarium (wopo, near ; ovarium, ovaiy),
992
origin of, 998
Pars ciliaris retinae, 725
intermedia of vestibule, 979
Patella (a dish or plate), 103
ligaments of, 155
ossification of, 115, 116
Patellar (patella) plexus, 667
Pavement epithelium, liii
Pectineal (pecten, a name of the pubic
bone) line, 96
Pectin eus muscle, 276
Pectoral region, dissection of, 1061
Pectoralis muscle, 203, 206
Pedicle of vertebrae, 4
Peduncles of cerebellum, 522, 557
development of, 577
of cerebrum, 536
development of, 578
of corpus callosum, 539, 542
of pineal gland, 552
Pelvic fascia, 260
plexus, 703
Pelvis (a basin), 93, 97
articulations of, 147
axis of, 99
brim of, 97
compared with shoulder^ 116
Pelvis — eontinued.
development of, III, 112
differences in the sexes, 100
dimensions of, 100
dissection of, 1076
fasciae of, 260
lower or true, 97
position of, 98
upper or false, 97
of kidney, 928
Penis, 955
corpora cavernosa of, 956
corpus spongiosum of, 958
development of, 1001
glans of, 955
helicine arteries of, 958, 959
integument of, 955
ligament, suspensory, of, 955
muscles of, 264
nerves of, 671, 703, 956, 959
prepuce of, 955
vessels of, 428, 956, 958, 959
Penniform (penna, a feather ; forma,
shape) muscles, cxvii
Pepsin (7T67TT&J, I digest), v
Peptic (TTCITTW, I digest), glands, 837
Perforans muscle, in hand, 219
in foot, 286
Perforated space, anterior, 539
posterior, 536
Perforatus muscle, of hand, 217
of foot, 289
Pericardiac arteries, 374, 402
Pericardium (vepi, about ; KapSia, the
heart), 300
dissection of, 1067
vestigial fold of, 300
Perichondrium (irept, about ; xov^P05>
cartilage), Ixxxi
Pericranium (irepi, about ; Kpaviov, the
skull), 169
Perilymph (irepi, about; lympha, water),
753, 757
Perimysium (irept, around ; p.vs, a muscle),
cxvi
Perinseum (wept, about ; vatca, I am
situated), blood-vessels of, in re-
lation to lithotomy, 1046
development of, 1001
dissection of, 1037, 1069
fascia of, 259, 1039
muscles of, 261
raphe of, 1038
Perineal arteries, 426, 427, 428
fascia, 259, 1040
nerve, 670
Perineurium (irept, about; vevpov, a
nerve), cxliv
Periodontal (irfpi, about ; 65ovs, a tooth)
surface of teeth, 791
Periosteum (irepi, about ; oareov, a bone),
Ixxxvii, c
Peristaltic (Trepio-TeAAw, I constrict or
narrow) movement of the intes-
tines, 841
1132
INDEX.
PERITONEUM ("ffpt, about;
stretch), 826
continuity of, traced, 827
dissection of, 1072
at groin, 1024
folds of, 826
fossae or pouches of, 1024
ligaments formed by, 827
mesenteries of, 826
omenta of, 827, 828
parietal and visceral portions, 826
smaller cavity of, 827
structure of, 826
Perivascular canals, clxxxiii
Peroneal (irepovi), the pin of a buckle,
the fibula) arteries, 444, 445
bone, 105
nerve, 679, 680
Peronei muscles, 281, 282
Peroneo-tibial articulation, 158
Pes anserinus (goose's foot), 611
accessorius, 544
hippocampi, 544
Petit, canal of, 736
Petrosal artery, 752
nerves, 605
sinus, 463
Petrous (trfrpa, a rock) ganglion, 616
portion of the temporal bone, 37
Peyer's glands, 841, 846
Phalanges (<f>a\ay^, a rank of soldiers) of
fingers, 87
articulations of, 145
ossification of, 90, 93
of toes, no
articulations of, 166
ossification of, in, 115
Pharyngeal artery, 357
nerves. See NERVES
plexus, 617, 622, 690
PHARYNX (<(>apvy£), 187, 819
dissection of, 1058
glands of, 820
mucous membrane of, 820
muscles of, 187
Phrenic (<ppr)v, the diaphragm) arteries,
374, 4i6
centre, 245
nerve, 640
Pia mater, 564
development of, 582
Pigment, Ixiii
chemical composition of, Ixiv
of choroid, 718
iris, 719
use of, Ixv
Pigment-cells, movements in, xx
Pillars of abdominal ring, 250, 1019
fauces, 189
fornix, 545
iris, 716
Pineal gland, 552
development of, 579, 580
Pinna (a feather), 740
cartilage of, 741
Pinna — continued.
ligaments of, 742
muscles of, 170, 742
nerves and vessels of, 743
Pisiform (pisum, a pea ; forma, shape)
bone, 85
articulations of, 144
Pit of stomach, 831
Pith of hair, ccviii
Pituitary (pituita, phlegm or mucus)
body, 539
fossa, 39
membrane of nose, 774
Plantar ( planta, the sole of the foot) ar-
teries, 446, 447
fascia, 296
ligaments, 161-166
nerves, 677. See NERVES
Plantaris muscle, 285
Planum temporale (temporal plane),
32
Plasma (nAacrcra, I form) of blood, xxvii,
xxxii
salts in, xli
of chyle, xlix
of lymph, xlviii
Plastic (v\ao-(ru, I form) force, viii
Plate, central, of ethmoid, 42
mesial, of embryo, 859
of vomer, 48
orbital of frontal bone, 33
of ethmoid, 43
palate, of palate bone, 46
of superior maxilla, 44
tympanic, 37
of vertebra, 4
vertical of palate, 47
Plates, visceral, of embryo, 859
Platysma myoides (Tr\arva^a, a plate,
from ir\arvv<a, I extend ; fivs, a
muscle ; eiSos, shape), 178
Pleura (irAei/po, a rib or side) costalis,
893
pulmonalis, 893
Pleurae, 892
dissection of, 1066
mediastinum or partition of, 893
nerves of, 894
structure of, 894
Pleurapophysis (irAevpa, aside ; apophysis],
22
Pleuro-peritoneal cavity, 859
Plexiform origin of lymphatics, clxxxii
PLEXUSES of nerves, cxlvi
in muscle, clvi
aortic, 702
brachial, 641
branches of, 643
cardiac, 690, 698
carotid, 689
cavernous, 689, 690
cervical, 636
branches of, 638
posterior, 634
coeliac, 701
INDEX.
1133
PLEXUSES — continued.
coronary, anterior, 699
posterior, 699
of the stomach, 701
cranial, 688
cystic, 702
diaphragmatic, 699
epigastric, 699
gangliosus, 703
gastro-duodenal, 702
epiploic, 702
left, 702
hepatic, 701
hypogastric, 702
infraorbital, 602
intermesenteric, 702
inferior, 702
lumbar, 658
branches of, 659
myentericus (musculo-intestinal
"plexus), 851
ojsophageal, 623
pancreatic, 702
patellar, 667
pelvic, 703
pharyngeal, 617, 622, 690
preaortic, 695, 698
prevertebral, 687
prostatic, 703
pulmonary, anterior, 623
posterior, 623
pyloric, 702
renal, 701
sacral, 669
solar, 699
spermatic, 701
suprarenal, 699
tonsillar, 618
tympanic, 617, 752
vaginal, 704
vesical, 703
Plexuses of absorbent vessels, clxxxii
interlaminar, 850
PLEXUSES of veins, choroid, 460, 548
of fourth ventricle, 526
of lateral ventricle, 543
of third ventricle, 548
htemorrhoidal, 479
ovarian, 474
pampiniform, 474, 975
prostatic, 479
pterygoid, 457
spermatic, 474
subperitoneal arterial, 418
uterine, 479
vaginal, 479, 982
vertebral, 471
vesical, 478
Plica gubernatrix (guiding fold), 1000
semilunaris (semilunar fold), 705
Plis de passage (connecting convolutions
of brain), 536
Pneumogastric (irveu^wv, the lung ;
7CUTTTJP, the stomach) nerve. See
NERVES
Pomum Adami (Adam's apple), 906
Pons Tarini (bridge of Tarin;, 537
Pons Varolii (bridge of Varolius), 514,
521
Popliteal (poples, the ham) space, dissec-
tion of, 1079
Popliteal artery. See ARTERY
Popliteus muscle, 285
Porta (gate), or portal fissure, 867
Portal canals, 873
fissure of liver, 864
vein, 479, 867, 873
blood of, xliii
circulation in, clxvi
Portio dura, 610
mollis of seventh cranial nerve,
cxlix, 615
Porus opticus (optic pore), 726
Postsphenoid bone, 68
Pouch, recto- vesical, 857
Pouches, laryngeal, 913
Poupart's ligament, 249
Preformative membrane, 797
Pregnancy, changes in uterus during,
987
Premaxillary bone, 70
Premolar teeth, 782
Prepuce (prceputium, the foreskin),
955
development of, 1001
Presphenoid bone, 68
Pressure, effects of on skull, 74
Prevertebral fascia, 198
plexus, 687
Primary cerebral vesicles, 575
Primitive band or axis of nerve-fibre,
cxxxvi
groove, 573
kidneys, 993
sheath of nerve-fibre, cxxxvi
trace in embryo, 15
vertebrae, 16
Primordial (primus, first ; ordior, I
begin) cranium, 65
kidneys, 993
utricle, x, xiii
in cartilage, Ixxxi
vertebrae, 16
Process of bone, Ixxxviii
acromion, 76
angular of frontal bone, 34
auditory, external, 37
basilar, 29, 31, 59
clinoid, posterior, 39
cochleariform, 38
coracoid, 76
coronoid of lower jaw, 52
ulna, 82
cuneiform, 43
ensiform, 23
falciform, 293
frontal, lateral, 65
middle, 65
hamular, 41
of helix, 742
1134
INDEX.
Process — continued.
malar, 45
mastoid, 36, 59
nasal, 46
external, 65
internal, 65
odontoid, 9
olivary, 39
orbital of palate bone, 47
pterygoid, 41, 59
pyramidal, 47
sphenoidal, 48
spinous of sphenoid bone, 40, 59
styloid of temporal bone, 37, 59
of radius, 81
of ulna, 83
supracondyloid, 80
turbinated, superior and inferior,
43
uncinate, 43
vaginal, 37
vermiform, 522
xiphoid, 23
zygomatic, 36
Processes, ciliary, 717
of incus, 749
of malleus, 748
mammillary, of lumbar vertebrae, 7
of vertebrae, articulating, 4, 6, 7, 8,
9, 10
spinous, 4, 6, 8, 10
transverse, 4, 6, 8, 10
serial relations of, 116
Processus a cerebello ad cerebrum, 552,
a cerebello ad testes, 522
arciformes, 517
brevis, 748
cochleariformis (spoon-shaped pro-
cess), 38
cuneatus (wedge-shaped process),
5i8
gracilis, 748
obtusus of the malleus, 748
reticularis of spinal cord, 511
vaginalis peritonsei, 965, 1000
Prognathous (vpo, forward ; yvaOos, a
jaw) skulls, 73
Promontory of sacrum, 10
of tympanum, 746
Pronation and pronator (promts, having
the face downward), 228
Prosencephalon (irpos, before ; tyKffyaXov,
the brain), 577
PROSTATE (u-po, before ; /O-TTJ^I, I place)
GLAND, 952
anterior, 963
development of, 1001
fluid of, 954
levator muscle of, 953
structure of, 954
surgical anatomy of, 1040
vessels and nerves of, 954
Prostatic fluid, 954
plexus, 703
Prostatic — continued.
portion of urethra, 96 1
sinus, 961
Protoplasm (irpuros, first ; ir\a<T<rii>, I
form), xv
movements of, xix
Protoplast, xv, xxiv
Protuberance, occipital, external, 30
internal, 31
Proximate constituents of the body, 5
Psoas (if/oo, the loin) muscles, 272, 273
Pterygoid (irrepul, a wing ; ei'Sos, shape)
arteries, 356
bones, 68
canal, 42
foramen or canal, 42
fossa, 41
muscles, 181
processes, 41, 59
Ptery go-maxillary fissure, 57
ligament, 176
Pterygo-palatine artery, 357
canal, 41
Pubic arch, 97
artery, 424, 434
articulation, 149
bone, 95
ossification of, no, in
Pubo-prostatic ligaments, 952
Pudic artery. See ARTERY
nerve, 670
Pulmonary artery. See ARTERY
circulation, clxvi
plexuses, 623, 903
Punctum lachrymale, 709
Puncture of bladder, 1042
Pupil of eye, 718
form and size of, Jig
membrane of, 721
Pylori c artery, 408
orifice of stomach, 831
Pylorus (irvXwpos, a gate-keeper), 838
Pyramid in cerebellum, 524
in thyroid body, 921
in tympanum, 746
Pyramidal bone, 84
process of palate bone, 47
Pyramidalis muscle, 255
Pyramids of medulla oblongata, anterior,
Sr5
development of, 577
posterior, 516
of kidney, 929
Pyriformis (pyrus, a pear; forma, shape)
muscle, 268
RACEMOSE (racemus, a cluster of grapes)
glands, ccxxii
Radial artery, 394
nerve, 653
Radio-carpal articulation, 142
Radio-ulnar articulation, 138
Radius (a ray, or the spoke of a wheel),
80
INDEX.
1135
Radius — continued.
connection of, with ulna, 138
ossification of, 90
Ramus (a branch) of ischium, 96
of lower jaw, 51
of pubic bone, 95
Raiiine (rana, a frog ; also a swelling
under the tongue) artery, 349
U, I
of corpus callosum, 542
Raphe (fafyn, a seam ; from ^OTTTCU, I sew)
of medulla oblongata, 517, 519
perina?um, 1038
pons Varolii, 521
scrotum, 964, 1001, 1038
tongue, 805
Rathke's researches on the foetal heart,
527
Receptaculum chyli, 487, 1075
Recto-uterine folds, 986
Recto-vesical fascia, 260
folds, 947
pouch, 857
Rectum (intestinum rectum, the straight
intestine), 856
dissection of, 1077
position and course of, 856
structure of, 858
surgical anatomy of, 1041
vessels and nerves of, 858
Rectus muscle. See MUSCLES
Recurrent arteries. See ARTERY
nerves. See NERVES
Reflex movements, cxxxii
Regeneration of areolar tissue, Ixxiv
of bone, cxv
cartilage, Ixxxv
fibrous tissue, Ixxvi
hair, ccxiv
mucous membranes, cci
muscular tissue, cxxviii
nails, ccviii
nerves, clxv
pigment, Ixv
serous membranes, cxciii
skin, ccxviii
textures, xxvi
Region, abdominal, dissection of, 1069
cervical, dissection of, 1052
gluteal, dissection of, 1078
hypogastric, 824
ischio-rectal, 1037
sublingual, dissection of, 1057
submaxillary, dissection of, 1057
Reil, island of, 532, 534
Reissner, membrane of, 760, 761
Renal (ren, the kidney) artery, 414, 935
plexus, 701
Renes succenturiati, 939
Renovation, molecular, xxv
Reproduction, i
Respiration, organs of, 888
movements of, 246
Restiform (restis, a cord ; forma, shape)
bodies, 516, 518, 519
development of, 577
Rete mirabile, Iv, clxviii
Rete mucosum, ccii
Rete vasculosum testis, 970
Reticular tissue, Ixx, Ixxix
Reticulum (dim. of rete, a net) of nervous
tissue, cxli, 511
Retiform (rete, a net ; forma, shape),
connective tissue, Ixxix
of brain and spinal cord, cxli
Retina (rete, a net), 725
ciliary part of, 730
columnar layer of, 727
connection of elements of, 728
contents of in yellow spot, 729
development of, 738
granular layer of, 727
internuclear layer of, 728
limiting membrane of, 728
nervous layer of, 728
physical characters of, 725
structure of, 726
vessels of, 729
Retinacula (restraining bands) of ileo-
caecal valve, 853
of tendons. See Annular Ligaments
Retrahens auriculam muscle, 171
Retroperitoneal membrane, 826
Retzius' classification of skulls, 73
Rhomboideus (po^os, a rhomb, or equi-
lateral four-sided figure with ob-
lique angles ; ei'Soy, shape) muscles,
major and minor, 202
Ribs, 24
articulations of, 128
cartilages of, Ixxxiii
development of, 27
Rigor mortis, cxxxi
Rima (cleft) of pudendum, 977
glottidis, 910, 912
Ring, abdominal, external, 250, 1019
internal, 258, 1023
crural, 258, 1033
Risorius (rideo, I laugh) muscle, 176
Rivini, ducts of, 818
Rods of Corti in ear, 764
of retina, 727
Rolando, fissure of, in the brain, 533
Root-sheath of hair, ccx
Rosenmiiller, organ of, 992
Rostrum (a beak) of corpus callosum,
542
of sphenoid bone, 39
Rotation, 120
Rotatores spinse, 238
Rotula (dim. of rota, a wheel), 103
Ruga3 (wrinkles) of mucous membrane,
cxcvi
of stomach, 835
vagina, 981
Ruysch, tunic or membrane of, 717
SAC of hernia, 1025, 1035
lachrymal, 709
of omentum, 827
1136
INDEX.
Saccular (saccuhls, a little bag) glands,
ccxxii
Saccule of larynx, 912
of vestibule, 757
Sacculus, vesical, 951
Sacral (sacrum) arteries, 418, 430
foramina, n
nerves, 668
plexus, 669
Sacro-iliac articulation, 147
Sacro-lumbalis muscle, 234
Sacro -sciatic foramina, 149
ligaments, 148
Sacro-vertebral ligament, 147
Sacrum (os sacrum, the sacred bone ;
because formerly oifered in sacri-
fices), 10
articulations of, 147
ossification of, 19, 21
Sacs of milk-teeth, 794, 795
of permanent teeth, 801
Sagittal (sagitta, an arrow) suture, 55
Saliva, 818
Salivary glands, 814
development of, 819
Salivine, 818
Salpingo-pharyngeus (craKiriyl, atrumpet ;
<f>apvy£, the pharynx) muscle, 189
Santorini, cartilages of, 9of
fissures of, 742
Saphenous (a-a^vris, manifest) nerve,
external, 666
opening, 292
veins, 475, 476
Sarcode (cra/>{, flesh), contractions in,
xx
Sarcolemma (<rapt, flesh ; Ae/u/tct, a husk),
cxviii
Sarcous elements of muscle, cxix
Sarkin, xl, cxxviii, cxxxiv
Sartorius (sartor, a tailor) muscle, 273
Satellite (satelles, an attendant) veins,
cxxiii
Scala tympani (scala, a stair), 756
vestibuli, 756
Scalenus (O-KCCATJJ/OS, with unequal sides)
muscles, 193, 195
Scaphoid (ffKa^r), a skiff or boat ; elSos,
shape) bone of foot, 108
ligaments of, 161, 163
ossification of, 115
bone of hand, 84
ligaments of, 142
ossification of, 93
Scapula (probably = (T/COTTOKT;, a spade),
74
ligaments of, 134, 136
ossification of, 89, 90
Scapular artery, 367, 373
Scapulo-clavicular articulation, 134
Scarf-skin, liv, cci
Scarpa's foramina, 45
triangle, 434
Schindylesis (o-xivSuAeo), I split), 119
Schleiden's views on cell-growth, xix
Schlemm, canal of, 721
Schneiderian membrane, 774
Schwann's views on cell-growth, xix
Sciatic (Iffxwv, the hip) artery, 429
nerves, 673, 675
Sclerotic (<r/cArjpos, hard) coat, 711
structure of, 713
Sclerotome (tr/cAr/pcy, hard ; re^ixa, 1
cut), 1
Scrobiculus (a small pit) corclis, 824
Scrotal hernia, 1025
Scrotum (a hide), 964
dartos tunic of, 257
development of, 1001
Sebaceous (sebum, suet) glands, ccxvii
development of, ccxviii
Secondary deposits in cells, xii
SECRETING APPARATUS, ccxix
cells, ccxx
fringes, ccxxi
glands, ccxviii
membrane, ccxxi
SECRETION (secer/w, I separate), ccxix
cell-agency in, ccxx
Segmentation of yelk-mass in ovum, xv
Segments of trunk, I
relation of limbs to, 117
Sella Turcica (Turkish saddle), 39
Semen, 975
Semicircular canals, 754
membranous, 758
Semilunar bone, 84
Semimembranosus muscle, 271
Seminal granules, 956
ducts, 974
vesicles, 973
Seminiferous tubes, 969
Semipeuniform muscles, cxvii
Semispinalis muscle, 237
Semitendinosus muscle, 271
Sensation, cxxxii
Sense, muscular, cxxviii, cxxix
Senses, organs of, 705
Sensibility of muscles, cxxix
Sensory terminal organs, cl
Septa, intermuscular, of arm, 230
foot, 296
thigh, 293
Septula renum, 929
Septum (a partition, from sepio, I hedge
in) of auditory ampullae, 758
crurale, 1035
of heart, auricular, 309
development of, 323
fibres of, 320
ventricular, 310
lucidum, 543, 545
• of medulla oblongata, 517, 519
nasi, 771, 772
of nose, osseous, 61
pectiniforme (comb-like partition),
957
of pons Varolii, 521
scroti, 964
sphenoidal, 39
INDEX.
1137
Septum — continued.
subarachnoid, 565
of tongue, 8n
Serial horaology, 2
relation of parts of vertebrae, 2 1
Sorolin, xl
Serosity, xxxix
SEROUS MEMBRANES, General Anatomy
of, cxci
arrangement of, cxci
epithelium of, liii
fluid of, cxciii
folds of, cxci
inflammation of, cxciii
reparation of, cxciii
structure and properties of, cxcii
vessels and nerves of, cxcii
Serous vessels, clxxx
Serrated (serra, a saw) suture, 119
Serratus muscle. See MUSCLES
Serum of blood, xxvii, xxxix
of chyle, xlix
lymph, xlviii
muscle, cxxviii
Sesamoid (ffrjcrafj.oi', a kind of small
grain ; et'Sos, shape) bones of
fingers, 88
of toes, no
fibro- cartilages, Ixxxvii
Sheath of arteries, clxviii
crural, 293
of muscles, cxvi
of nerve-fibre, medullary, cxxxvi
primitive, cxxxvi
of nerves, common, cxliv
of funiculi, cxliv
Sheaths, synovial, cxcv
Shin-bone, 103
Short bones, Ixxxviii
Shoulder-joint, bones of, 74
compared with pelvis, 116
dissection of, 1064
ligaments of, 136
Sigmoid (£, a form of the letter eiy^a.
sigma ; flSos, shape) artery, 412
cavity of ulna, 82
notch, lower jaw, 52
flexure of colon, 854
valves, 307
aortic, 313
pulmonary, 310
Sinus (a hollow) of aorta, 335
basilar, 464
cavernous, 463
nerves in, 594
circular, 463
circularis iridis, 721
coronary, of heart, 310, 483
falciformis inferior, 462
falciformis superior, 462
frontal, 34, 64
of jugular vein, 459
kidney, 928
lateral, 462
longitudinal, inferior, 462
Sinus — continued.
longitudinal, superior, 462
lymph, clxxxvii
maxillary, 46, 64
occipital, anterior, 464
posterior, 463
pedis, 161
petrosal, inferior, 463
superior, 463
of portal vein, 480
pocularis (cup-like sinus), 961
prostatic, 961
quartus or straight sinus, 462
transverse, 462, 464
uro-genitalis, 995, 1001
of vestibule, 757
Sinuses, cranial, 64, 461
ethmoidal, 64
frontal, 64
of larynx, 913
maxillary, 46, 64
sphenoidal, 39, 64
ol'Valsalva, 308
aortic, 313, 335
pulmonary, 311
venous, of cranium, 461
confluence of, 462
dissection of, 1051
of veins, clxxiv
SKELETON (o-/ceAAo>, I dry), 2
adapted to erect posture, 1 1 7
SKIN, General Anatomy of, cci
basement membrane of, cciii
chemical composition of, ccvi
cuticle. See Cuticle
cntis vera, derma, or corium, cciii
development of, ccvi
epidermis, cci
functions of, ccxviii
furrows of, cciv
glands of, sebaceous, ccxvii
sudoriferous, ccxvi
lymphatics of, ccv
Malpighian layer of, ccii
nerves of, ccvi
papilhe of, cciv
pigment of, ccii
reproduction of, ccxviii
rete mucosum of, ccii
structure of, cciii
thickness of, ceiv
true, cciii
vessels of, ccv
vital properties of, ccxviii
SKULL, anterior region of, 55
base of, external, 59
internal, 61
bones of, 29
analogy with vertebrae, 94
development of, 64
external surface, 55
forms of, 72
fossee of, 61
general conformation of, 55
internal surface, 60
4 E
1138
INDEX.
SKULL— continued.
internal fossse of, 6 1
lateral region of, 57
muscles of, 169
superior region of, 55
sutures of, 53
vertebral theory of, 71
Sinegma prseputii, 955
Scernmering's classification of cranial
nerves, 582
Solar (sol, the sun) plexus, 699
Soleus (solea, a sandal, or sole of a shoe,
also a sole fish), 284
Somatome (<rca/j.a, a body ; repi/co, I cut), I
Space, perforated, anterior, 539
posterior, 536
Spaces, Haversian, of bone, xciii
SPERMATIC cord, coverings of, 965, 1023
vessels and nerves
of, 967
relation to inguinal hernia,
1025, 1027, 1029
structure of, 1023
fascia, 965
filaments, 976
Spermatic artery, 414, 975
Spermatozoa ((rirfpfta, seed ; £ft>0*'» an
animal), 975, 976
Sphenoid (atytiv, a wedge ; eZSos, shape)
bone, 38
ossification of, 68
Sphenoidal fissure, 41, 57, 61
process of palate bone, 48
septum, 39
sinus, 39, 64
spongy bones, 39, 40, 69
Spheno-maxillary fissure, 57
fossa, 57
Spheno-palatine artery, 357
foramen, 48, 58, 63
ganglion, 603, 1057
Spheno-parietal suture, 55
Spheroidal epithelium, liii, Iviii
Sphincter (o-Qiyya, I bind) of rectum,
external, 262
internal, 859
oris, 175
of pupil, 719
vaginae, 266, 932
vesicse, 949
Spigelius, lobule of, 864
SPINAL CORD, Descriptive Anatomy of,
502
blood-vessels of, 567
cells of grey matter in, 510
central canal of, 508
ligament of, 503
columns of, 506
course of fibres in, 511
commissures of, 507
connective tissue of, 510
development of, 574
dissection of, 1061
fissures of, 506
grey matter of, 509
SPINAL CORD— continued.
length and form of, 504
ligaments of, 503, 566
membranes of, 502, 563, 564
minute structure of, 509
origin of nerves from, 511
sections of, 511
Vesicular tract of, 510
weight of, 572
Spinal arteries. Sec. ARTERIES
SPINAL NERVES, 628. See NERVES
divisions of, anterior, 635
posterior, 632
roots of, 630
Spinales. See MUSCLES
Spine. See Vertebral Column
Spine, ethmoidal, 39
hpemal, 23
of ilium, anterior and posterior,
94
ischium, 96
nasal, 34, 45
neural, 22
occipital, 30
of os pubis, 95 «
scapula, 75
tibia, 103
Splanchnic nerves, 695, 696
Splanchnology (<nr\ayxi'a> bowel ; Ao7os,
discourse X 779
Spleen (mrAip'), 883
accessory, 884
coats of, 884
corpuscles of, 887
development of, 888
dissection of, 1074
hilus or fissure of, 883
lymphatics of, 887
nerves of, 887
position of, 824, 883
pulp of, 886
size and weight of, 884
structure of, 884
trabeculse of, 884
vessels of, 408, 886
Splenculi (little spleens), 884
Splenic arteries, 418, 886
flexure of colon, 854
Splenius (splenium, a pad) muscle, 234
Spongy bones, ethmoidal, 43
inferior, 50, 70
sphenoidal, 39, 40, 69
cartilages, Ixxxvi
structure of bone, xc
Spot, germinal, of ovum, xv, 990
Squamous (squama, a scale) suture,
119
Stapedius (stapes) muscle, 75 1
Stapes (a stirrup), 749
development of, 66
Stearin (o-reap, tallow), Ixvii
Stellulse of Yerheyen, 937
Stenson, duct of, 816
foramina of, 45
Sternal artery, 374
INDEX.
1139
Sterno- clavicular articulation, 134
Sterno-hyoid muscle, 191
Sterno-mastoid artery, 351
muscle, 193
Sterno-thyroid muscle, 191
Stimuli of muscular contraction, cxv,cxxx
Stomach, 830
alveoli of, 835
changes in colour of, after death, 834
coats of, 832
connections of, 831
development of, 860
dimensions of, 831
dissection of, 1073
epithelium of, 837
follicles of, 837
glands of, 836
lymphatics of, 838
mucous membrane of, 834
muscular coat of, 832
nerves of, 838
position of, 826, 830
pylorus, 838
rugae of, 835
shape of, 831
structure of, 832
tubules of, 835
vessels of, 407, 837
Stratified epithelium, liv
Stratum bacillorum (layer of rods), 727
ferrugineuin (rust-coloured layer),
cxlviii
Stria cornea (the horny streak), 550
vascularis, 768
Strise longitudinales, 542
Striated layers of arteries, clxix
Stripes, cross, of muscle, cxvii
cause of, cxix
Stroma (o-Tpca/ua, a bed), hilus-, of lym-
phatic glands, clxxxvii
intertubular, of kidney, 938
of ovaries, 989
of suprarenal bodies, 939, 941
Structural elements of the body, iv
Stylo-glossus muscle, 186
Stylo-hyoid ligament, 133
muscle, 184
Styloid (<TTV\OS, a style or pen ; et'Sos,
shape) process, 37, 59
Stylo-mastoid artery, 353, 752, 768
Stylo-maxillary ligament, 133, 197
Stylo-pharyngeus muscle, 187
Subarachnoid fluid, 566
space, 565
Subclavian artery. See ARTERY
Subcrureus muscle, 276
Sublingual artery, 348, 349, 818
gland, 817
Sublobular veins of liver, 870
Submaxillary ganglion, 609
gland, 816
muscles, 183
Submental artery, 350, 351, 818
Submucous coat of intestines, 841
Suboccipital nerve, 632
Subperitoneal layer of areolar tissue, 826
Subscapular arteries, 373, 379
fossa, 74
nerve, 645
Substantia cinerea gelatinosa, 507, 519
spongiosa, 508
Sudoriferous glands, ccxvi
development of, ccxvii
Sulci (furrows) in brain, 531
Sulcus frontalis, 35
spiralis, 761
Superciliary ridge, 33
Supination (supinus, lying on the back),
muscles of, 228
Supinator muscles, 220, 223
Supra-acromial artery, 373
Supracondyloid eminence, 79
Supraniaxillary nerve, 615
Supraorbital artery, 360
foramen, 34, 56, 57
nerve, 598
SUPRARENAL BODIES, 939
accessory, 942
cortical part of, 939
development of, 994
function of, 942
medullary part of, 940
nerves of, 941
size and weight of, 939
stroma of, 939, 941
vessels of, 941
Suprarenal artery, 413
plexus, 699
Suprascapular artery, 366, 371
nerve, 644
Supraspinatus muscle, 209
Supraspinous fossa, 74
Supratrochlear nerve, 597
Sural (sura, the calf) artery, 442
SURGICAL ANATOMY, 1005
of arteries, brachial, 1010
carotid, common, 1005
epigastric, 1023
iliac, common, 1012
external, 1014
internal, 1014
femoral, 1015
subclavian, 1007
ischio-rectal fossse, 1043
hernia, femoral, 1031
inguinal, 1018, 1025
perinseum, 1037
peritonaeum, at groin, 1022
Sustentacular (sustentaculum, a support)
connective tissue, Ixxix
Susteutaculum tali (the support of the
astragalus), 107
Suture (sutura, a seam), forms of, 119
coronal, 54
frontal, 55, 67
fronto-parietal, 54
lambdoidal, 54
occipito-mastoid, 55
occipito-parietal, 54
parietal, 55
4 E 2
1140
INDEX.
Suture — contin ued.
parieto-mastoid, 55
sagittal, 55
spheno-parietal, 55
squamous, 55
temporo-parictal, 55
Sweat-glands, ccxvi
Sylvius, aqueduct of, 525, 550
fissure of, 530. See Fissure
ventricle of, 545
Sympathetic nerve. See NERVE, SYMPA-
THETIC
Symphysis (<rw, with, together ; <pva>, I
grow) of lower jaw, 51
pubic, 95, 100, 149
sacro-iliac, 147
Synarthrosis (<rvv, with, together ; apOpov,
a joint), 119
Synchondrosis (<rw, with, together ; xoj/-
Spos, cartilage), sacro-iliac, 147
Synostosis (<TVI>, with, together ; ovreov, a
_bone), 73
Synovia (<rw, with ; wov, an egg), cxcv
Synovial bursee, cxciv
capsules, cxciii
fluid, cxcv
folds or fringes, cxciv
membranes, cxciii
of ankle, 160
articular, cxciii
of atlas, 125
of axis, 126
bursal, cxciv
carpal, 144
costo-sternal, 130
costo-vertebral, 129
of elbow-joint, 141
of hip, 152
intervertebral, 122
of knee-joint, 156
of lower jaw, 133
metacarpal, 146
metatarsal, 166
peroneo-tibial, 158, 159
radio-carpal, 142
radio-ulnar, 139
of ribs, 129
sacro vertebral, 147, 35
scapulo-clavicular, I
of shoulder-joint, 137
sterno-clavicular, 134
tarsal, 162, 163, 164
tarso- metatarsal, 165
vaginal, cxcv
of vertebrae, articulating, 123
vesicular, cxciv
vessels of, cxciv
sheaths, cxcv
Syntonin (<rvv, together ;
stretch), ccxxviii
Systemic circulation, clxvi
vessels, 332
Systems, organic, iii
TABLES of skull, 60
Tabular bones, lixxviii
epithelium, liii
Tactile (tactus, touch) corpuscles, cli,
ccvi
papillae, ccvi
Tsenia (raivia, a band or ribbon) semi-
circularis, 543, 550
Tsenia hippocampi, 544, 546
Talo-calcaneal (talus, the astragalus ;
calcaneum, heel-bone) ligaments
160
Talo-scaphoid (talus, the astragalus ;
scaphoid) ligament, 161
Talus (a die), 107. See Astragalus
Tapetum (a carpet), 718
Tarsal (tarsus, the cartilage supporting
the eye) cartilages, 706
Tarso-metatarsal articulations, 164
Tarsus (rapcros, the .upper surface of the
foot), 1 06
compared with carpus, 115
ligaments of, 164
ossification of, in, 115
Tauro-cholic (taurin [ravpos, a bull] ;
XoArj, bile) acid, 879
Taxis (ra|ts, an arranging) in femoral
hernia, 1036
inguinal hernia, 1030
TEETH, 780
arrangement in jaws, 783
bicuspid, 782
canine, 781
cavity of, 785
cement of, 791
formation of, 799
changes in jaw during growth of,
804
characters of, general, 780
classification of, 780
crusta petrosa of, 79 1
cuspidate, 781
dentine of, 785
formation of, 797
tubules of, 786
dentine, secondary of, 792
development of, 792
enamel of, 789
formation of, 798
eye, 782
follicular stage of, 793
incisor, 781
intertubular substance of, 787
ivory of, 785
formation of, 798
milk, 784
molar, 783
nerves of, civ, 805
osteodentine of, 792
permanent, 780
calcification of, 803
cavities of reserve of, 80 1
development of, 800
eruption of, 803
special characters of, 781
primitive groove of, 793
INDEX.
1141
TEETH — continued.
pulp, dental, of, 785
primitive, 796
sacs of, 794
structure of, 784
temporary, 784
development of, 792
eruption of, 799
follicular stage of, 793
papillary stage of, 793
saccular stage of, 794
shedding of, 802
vessels of, 805
wisdom, 783
Tegmentum of crura cerebri, 556
Tela choroidea (the choroid web), 548
Temporal (tempora, the temples) arteries,
353, 354, 356
bone, 35
fascia, 197
fossa, 57
muscle, 181
nerve. See NERVE
Temporo-maxillary articulation, 132
Temporo-parietal suture, 55
Temporo-sphenoidal suture, 55
Tendo Achillis (tendon of Achilles), 285
palpebrarum, 171
Tendon, cordifbrm or central, of dia-
phragm, 245
conjoined, 250, 1022
Tendons (TCIVW, I stretch), Ixxiv
connection with muscles, cxxi
Tensor (tendo, I stretch). See MUSCLES
Tentorium (a tent, from tendo, I stretch),
563
Tesselated (tessella, dim. of tessera, asmall
quadrangular stone in a pavement)
epithelium, liii
TESTES (testicles), 963, 967
capsule of, 968
coni vasculosi of, 970
coverings of, 963
vessels and nerves of, 967
descent of, 1000
development of, 995
epididymis of, 967
excretory duct of, 971
glandular substance of, 969
gubernaculum of, 1000
lobes of, 969
mediastinum of, 969
rete vasculosum of, 970
secretion of, 975
septum of, 968
structure of, 969
tubuli of, 969
recti of, 970
tunica albuginea of, 968
vaginalis of, 966
vasculosa of, 969
vas deferens of, 971
vasa efferentia of, 970
recta of, 970
vessels and nerves of, 975
TESTES— continued.
(in cerebrum), 554
muliebres, 988
TEXTURES in general, iii
chemical composition of, v
development of, ix
enumeration of, iii
nutrition and regeneration of, xxiv
particular. See TISSUE, &c.
permeability of, iv
physical properties of, iv
vital properties of, vii
Thalarui optici (optic couches), 550, 558
development of, 579
grey matter of, 561
Thebesius, foramina of, 309
valve of, 310
Theca vertebralis (vertebral sheath), 502,
563'
Thenar (dtvap, the palm of the hand)
prominence, 225
Thigh, bone of, 100
dissection of, 1080
muscles of, 266
Thoracic (thorax) arteries. See ARTERY
duct, 487
Thorax (Qwpa£, a breast-plate), 27
bones of, 23
dissection of, 1066
muscles of, 240
Thumb, muscles of, 225
action of, 229
Thymic (thymus gland) artery, 374
THYMUS GLAND, 923
central stem of, 924
chemical composition of, 924
development of, 925
fluid of, 924
lobes of, 923
lymphatics of, 925
structure of, 924
vessels and nerves of, 925
Thyro-arytenoid ligament, 910
muscle, 916
Thyro-hyoid ligaments, 909
muscle, 192
Thyroid artery, 346
axis, 371
THYROID (dvpeos, a shield ; ei'Soy, shape)
BODY or GLAND, 920
development of, 922
fluid of, 922
isthmus of, 920, 921
levator muscle of, 921
lobes of, 920
structure of, 921
vessels and nerves of, 922
weight of, 921
Thyroid cartilage, 906
Thyro-pharyngeus muscle, 1 88
Tibia (a pipe or flute, from its supposed
resemblance), 103
compared with ulna and radius, 115
ligaments of, 158
ossification of, in, 112
1142
INDEX.
Tibial artery. See ARTERY
nerve. See NERVE
TISSUE, adipose, Ixv
areolar, cellular, or filamentous, Ixix
cartilaginous, Ixxx
cavernous, clxxx
connective, Ixix
special varieties of, Ixxviii
homogeneous, Ixxix
jelly-like or mucous, Ixxviii
retiform, Ixxix
cuticular, lii
cytogenous, Ixxix
elastic, Ixxvi
epidermic, lii
epithelial, lii
erectile, clxxx
fibrous, Ixxiv
filamentous, Ixix
muscular, cxv
nervous, cxxxi
osseous, Ixxxvii
reticular, Ixxix
Toe, great, muscles of, 288, 289
Toes, bones of, 1 10
movements of, 166
muscles of, 280, 286, 289
Tomentum (flock of wool, hair, &c.), 564
TONGUE, 805
dissection of, 1058
f nen urn of, 805
glands of, 809
mucous membrane of, 805
muscles of, 185, 809
nerves of, 808, 812
papilla?, of, circumvallate, 806
conical and filiform, 807
fungiforni, 807
secondary, 808
raphe of, 805
septum of, 811
vessels of, 812
Tonicity (rovos, tension) of arteries, clxxi
Tonsillar artery, 350, 814
Tonsils, 813
vessels and nerves of, 814
Topographic anatomy, i
Torcular (a wine- or oil-press) Herophili,
462
Touch-bodies, cli
Trabeculse (dim. from trabs, a beam) of
corpus cavernosum, 957
lateral, of primitive cranium, 65
of lymphatic glands, clxxxvii
of spleen, 884
Trabs cerebri (corpus callosum), 541
TRACHEA (arteria trachea, the rough
artery ; rpaxvs, rough], 888
cartilage and fibrous membrane of,
890
development of, 904
elastic fibres of, 891
glands of, 892
mucous membrane of, 892
muscular fibres of, 891
TRACHEA — continued.
situation of, 888
structure of, 890
vessels and nerves of, 892
Trachelo-mastoid (rpaxrjAos, the neck ;
mastoid) muscle, 235
Tract, optic, 536, 554
Tractus intermedio-lateralis, 510
foraminosus spiralis, 756
Tragus (rpayos, a goat), 741
muscles of, 743
Transitional epithelium, Iviii
Trapezium (rpaire&oi', dim. of rpanffa, a
table), 85
Trapezoid bone, 85
ligament, 135
Trapezius muscle, 200
Trefoil tendon of diaphragm, 245
Triangle, cervical, anterior, 1053
posterior, 1052
of Hesselbach, 1027, 1029
Scarpa's, 434
Triangular ligament of urethra, 260
Tricuspid (tres, three ; cuspis, the point
of a weapon) valve, 310
Trigone (triangle, from rpets, three ;
yoavia, an angle) of bladder, 948
Trigonum vesica?, 948
Triquetral (triquetrus, three-cornered)
bones, 55
Trochaiiter (Tpoxo.vr-rjp , rpoxcuvct), rpox.0?,
words implying turning) major,
100
minor, 101
Trochlea (rpox'Aeo, a pulley) of humerus,
79
Trunk, articulations of, 121
muscles of, 233
attaching upper limb to, ante-
rior, 203
posterior, 200
nerves of, 682, 684
relation of limbs to segments of, 117
Tube, Eustachian, 747
membranous, of nerve-fibre, cxxxvi
Tuber annulare, 521
calcis, 107
cinereum, 538
Tubercle, grey, of Eolando, 519
laminated, 525
of Lower, 310
Tubercula quadrigemina, 552
development of, 578
grey matter of, 561
Tuberculum pharyngeum, 819
Tuberosity, bicipital, 80
of ischium, 96
palate bone, 47
superior maxillary bone, 45
Tubes, Fallopian, 991
development of, 996
uriniferous, 930
convoluted, 930
development of, 994
looped, 930, 934
INDEX.
1U3
Tubes — continued.
origin and course of, 933
straight, 930
Tubular glands, ccxxii
nerve-fibres, cxxxv
Tubules, dental, 786
Tubuli contort! (twisted or convoluted
tubes) of kidney, 930
recti of kidney, 970
seminiferi, 969
uriuiferi, 929
origin and course of, 933
Tulpius, valve of, 852
Tunica adiposa of kidney, 926
albuginea of testicle, 968
of ovary, 988
choroidea, 716
chorio-capillaris, 717
erythroides(epu0pos,red; et'Sos, form),
965
Ruyschiana, 717
vaginalis, 966
hernia in, 1025
vasculosa testis, 969
eye, 716
Turbinated (coiled, from turbo, a whirl)
bones. See Spongy bones
Tutamina oculi (defences of the eye),
705
Tympanic (tympanum, the dram of the
ear) artery, 356, 752
plate, 37
TYMPANUM (rv^Tcavov, a drum), or middle
ear, 744
apertures of, 746
bones or ossicula of, 748
cavity of, 744
development of, 769
ligaments of, 749
membrane of, 745
lining, 751
secondary, 746
muscles of, 749
seal a of, 756
vessels and nerves of, 752
walls of, 745
Tyson's glands, 955
ULNA (wAeyr/, the elbow), 81
compared with bones of leg, 115
ossification of, 90
ligaments of, 138
Umbilical (umbilicus, the navel) cord,
tissue of, Ixxii
fissure of liver, 864
region, 824
contents of, 826
Umbilicus, cicatrix of, 255
Unciform (uncus, a hook ; forma, shape)
bone, 86
Uncinate (uncus, a hook) process of
ethmoid bone, 43
Unguis os (the bone like a nail), 50
Upper limb, articulations of, 134
bones of, 74
Upper limb— continued.
compared with lower, 115
dissection of, 1059
fasciae of, 229
muscles of, 198
nerves of, cutaneous, 683
of muscles, 685
Urachus (ovpov, urine ; ex«, I hold), 945
formation of, 995
'Urea in blood, xl
URETERS (oupew, I pass urine), 942
course of, 942
development of, 994
orifices of, 948
structure of, 943
varieties of, 943
vessels and nerves of, 943
URETHRA (ovpov, urine), female, develop-
ment of, 980
mucous membrane of, 980
muscles of, 266
orifice of, 978
male, 959
bulb of, 958
crest of, 961
development of, 1001
fossa navicularis of, 962
glands and lacunae of, 962
length of, 959
ligament of, triangular, 260,
1040
mucous membrane of, 962
muscles of, 265, 962
orifice of, external, 955
internal, 948
portion of, membranous, 962
bulbous, 962
prostatic, 961
spongy, 962
sinus pocularis of, 961
Uric acid, xl, cxxviii, cxxxiv
Urinary bladder, 944. See BLADDER
organs, 926
development of, 992
Urine, 938
Uriniferous tubes, 929
development of, 994
Uterine artery, 422, 987
UTERUS (womb), 982
arbor vita? of, 984
body of, 983
cavity of, 984
cervix, or neck, 983
changes in, 987
development of, 996
double, 998
epithelium of, 985
fibres of, 985
functions of, 982
fundus of, 983
glands of, 985
gravid, changes in, 987
nerves of, 704
ligaments of, anterior and posterior,
985
1144
INDEX.
UTERUS— continued.
ligaments of,
broad, 986
round, 986
mucous membrane of, 985
muscular tissue, growth of during
gestation, cxxvii
nerves of, 704, 987
os, or mouth of, external, 983
internal, 984
tincse of, 982
position of, 825, 982
structure of, 984
tissue, proper, of, 984
vessels of, 422, 987
Utricle (utriculus, a small bag^, x, xiii
of male urethra, 961
of vestibule of the ear, 757
Uvea (uva, a cluster of grapes), 719
Uvula (dim. of uva) of bladder, 948
of cerebellum, 524
of throat, 189
muscle of, 190
VAGINA (sheath), 980
columns of, 981
development of, 1001
sphincter of, 266, 982
structure and connections, 982
Vaginal artery, 422
process, 37
synovial membranes, cxcv
Valsalva, sinuses of, 308, 311, 313
Vallecula of cerebellum, 523
Valve of Bauhin, 852
Eustachian, 309, 325
of foramen ovale, 325
ilio csecal, or ileo- colic, 852
mitral, or bicuspid, 313
of Thebesius, 310
tricuspid, 310
of Tulpius, 852
of Vieussens, 554
Valves, auriculo-ventricular, 305
of Kerkring, 842
lacrymal sac and canals, 710
lymphatics, clxxxv
sigmoid, or semilunar, of aorta, 307
pulmonary, 310
of veins, clxxiv
Valvulse conniventes, cxcvi, 842
Varicose nerve-fibres, cxxxvii
Vas aberrans of testis, 972
deferens, 971, 1023
development of, 996, 999
spirale (spiral vessel), 767
Vasa aberrantia, brachial, 385
aflferentia and efferentia of lym-
phatic glands, clxxxvi
brevia of the stomach arteries, 409
veins, 481
chylifera, 491
efferentia of testis, 970
development of, 999
lactea, 491, 844
Va sa — continued.
recta of kidney, 936
of testes, 970
serosa, clxxx
vasomm, arteries, clxxi
veins, clxxiv
lymphatics, clxxxv
vorticosa, 717, 722
Vascula serpeutina, 19, 69
Vascular glands, ccxxvi
Vaso-motorial nerves, clxiii
Vegetable structures, formation of, x
VEINS, General Anatomy of, clxxii
anastomoses of, clxxiii
coats of, clxxiii
contractility of, clxxiv
distribution of, clxxii
muscular fibres in, clxxiv
openings of lymphatics into, cxc
peculiarities of, clxxiv
plexuses of. See PLEXUSES
pulsation in, clxxiv
satellite, clxxiii
structure of, clxxiii
valves of, clxxiv
vessels and nerves of, clxxiv
vital properties of, clxxiv
VEINS, Descriptive Anatomy of, 452
acromial thoracic, 469
alar, 469
angular, 456
auricular anterior, 457
posterior, 457
axillary, 468
azygos, left, or small, 471
right, 469
basilic, 466
brachial, 467
brachio-cephalic, 453
bronchial, 471, 903
buccal, 456
capsular, 474
cardiac, 482
anterior, 483
great, 482
posterior, 483
small, 483
cava, lower, 473
upper, 453
of cerebellum, 460
cerebral, 460
cephalic, 466
of choroid coat, eye, 722
plexus, of brain, 548
circumflex iliac, 477
superficial, 475
of shoulder, 469
coronary, of heart, 321, 482
stomach, 480
of corpora cavernosa, 958
corpus striatum, 460
cranium, 460
dental, inferior, 457
superior, 457
diaphragmatic, 454
INDEX.
1145
VEINS — continued.
of diploe, 465
dorsal, spinal, 471
of peiiis, 479
duodenal, 481
enmlgent, 474
epigastric, 477
superficial, 475
of face, 455
facial, 455
communicating, 457
transverse, 457
femoral, 476
frontal, 455
of diploe, 465
of Galen, 460
gastric, 481
gastro-epiploic, 481
of head, 455
heart, 482
hepatic, 474, 867, 871
iliac, external, 477
internal, 477
common, 479
infraorbital, 456
innominate, 453
intercostal, anterior, 454
superior, 455
interlobular of liver, 873
intr a cranial, 460
intralobnlar of liver, 870
jugular, anterior, 459
external, 459, 469
internal, 459, 469
posterior, 459
labial, 456
laryngeal, 460
lingual, 459
of liver, 867, 871
of lower limb, 475
lumbar, 473
ascending, 473
mammary, internal, 453
masseteric, 456
maxillary, internal, 457
median basilic, 467
cephalic, 467
cutaneous, 467
mediastinal, 454
meningeal, 457
mental, 456
mesenteric, inferior, 482
superior, 481
nasal, 456
of neck, 455
occipital, 460
of diploe, 465
ophthalmic, 464
ovarian, 474
palatine, 456, 457
palpebral, inferior, 456
superior, 456
pancreatic, 481
parotid, 457
of pelvis, 477
VEINS — continued.
peroneal, 476
pharyngeal, 460
phrenic, 474
popliteal, 476
portal, clxvi, 479, 867, 873
sinus of, 480
pudic external, 75
pulmonary, 332, 903
radial cutaneous, 466
deep, 467
ranine, 456
renal, 474
of retina, 729
sacral, middle, 473
saphenous, long, or internal, 475
short, or external, 476
scapular, posterior, 459
spermatic, 473
spinal, 471
anterior longitudinal, 472
posterior longitudinal, 472
of spinal cord, 472
splenic, 480
subclavian, 469
sublobular of liver, 870
submaxillary, 456
submeutal, 456
subscapular, 469
supraorbital, 456
suprarenal, 474
suprascapular, 459
temporal, 457
deep, 457
middle, 457
superficial, 457
of diploe, 465
temporo-maxillary, 455
thymic, 454
thyroid, superior, 460
middle, 460
inferior, 453
tibial, 476
ulnar cutaneous, anterior, 466
posterior, 466
deep, 467
umbilical of foetus, 328
development of, 483
remains in adult, 865
of upper limb, 465
deep. 467
superficial, 466
vaginal, 479
of liver, 873
of vertebrae (bodies), 472
vertebral, 469
VEINS, plexuses of. See PLEXUSES.
Velum pendulum palati, 189, 813
interpositum of brain, 548
Vena cava, fossa of, in liver, 864
lower, 473
opening in diaphragm for,
246
upper, 453
cordis magna, 482
1146
INDEX.
Vena — continued.
hemiazygos, 471
portse, clxvi, 479, 867, 873
tributaries of, 480
salvatella, 466
sine pari, 469
Venae basis vertebrarum, 472
comites vel satellites (companion or
satellite veins), clxxiii, 467, 476
cordis ininimse, 309, 482
parvse, 483
Galeni (veins of Galen), 460, 548
Venous blood, characters of, xlii
Ventricles (ventriculus, dim. of venter, a
belly), cerebral, of Arautius,
517
of corpus callosum, 541
fifth, 545
fourth, 525
choroid plexuses of, 526
floor of, 517, 525
lining membrane of, 526
lateral, 543
choroid plexuses of, 543
cornua of, 543
of septum, or Sylvian, 545
third, 550
choroid plexuses of, 548
commissures of, 550
communication with lateral
ventricles, 548
of heart, 302
capacity of, 322
development of, 323
fibres of, 318
interior of, 305
left, 312
position of, in chest, 315
right, 310
of larynx, 910, 912
Ventro-inguinal (venter, the belly ; inguen,
the groin) hernia, 1027
Vermicular motion (vermiculust dim. of
vermis, a worm), 841
Vermiform process, 522
Vertebra dentata, 9
prominens, 8
VERTEBRAE, 3
cervical, 7
first and second, 8
coccygeal, 12 „
cranial, 71
dorsal, 5
fixed, 10
general characters of, 4
homologies of, 21
lumbar, 6
movable, 4
groups of, 5
number of, 4
ossification of, 15, 18, 20
primordial, 16
sacral, 10
serial relations of, 21
typical, 22
Vertebral aponeurosis, 240
artery, 367
column, 3
curves of, 13
form of, 14
ligaments of, 121, 147
ossification of, 15, 18, 20
veins of, 471
segments, I
Verumontanum (yeru, ridge), 961
Vesica prostatica, 961
urinaria (urinary bladder). See
BLADDER
Vesicle, primary auditory, 768
germinal, xv, 990
optic, primary, 737
secondary, 738
Vesicles, air, 899
of glands, cclxxxvi
of De Graaf, 989
changes in, 990
nerve, cxxxix. See NERVE-CELLS
seminal, 973
structure of, 974
vessels and nerves of, 975
of thyroid body, 921
Vesico-uterine folds, 986
Vesicular tracts of spinal cord, 5 10
Vessels. See ARTERIES, CAPILLARIES,
and VEINS
Vestibule, aqueduct of, 38, 754
of ear, 753
membranous, 757
saccule of, 757
scala of, 757
sinus of, 757
vessels of, 767
of vulva, 978
bulbs of, 979
Vestigial fold of pericardium, 300
Vestigium foraminis ovalis, 309
Vidian canal, 42, 57, 59
nerve, 604
Vieussens, isthmus of, 309
valve of, 554
Villi (villus, shaggy hair) cxcix
of small intestine, 842
stomach, 835
Vincula accessoria tendinum, 218
vasculosa, 218
Vis nervosa, viii, clxiii
Viscera of abdomen, 824
dissection of, 1069
position of, in regions, 826
of pelvis, dissection of, 1077
Visceral arches in embyro, 641
cavity, 3
plates, 859
Vital contractility, viii
properties of textures, vii. See each
tissue
Vitality, vii
Vite\\ine(vitelhis, yelk) duct and sac, 859
Vitreous (vitrum, glass) body, 731
table of skull, 60
INDEX.
11-17
Vocal cords, 910, 912
Voice, organs of, 905
Volar (vola, the palin of the hand)
artery, superficial, 397
Voluntary muscles, cxv
Vomer (a ploughshare), 48
ossification of, 70, 71
VULVA, 977
development of, 1001
erectile tissue of, 979
glands of, 978
mucous membrane of, 978
nerves of, 980
vessels of, 979
WH A ETON'S duct, 817
jelly, Ixxii, Ixxviii
Willis, classification of cranial nerves,
.582
circle of, 363
Wilson's muscle, 265
Wings, great, of sphenoid bone, 40
small, or of Ingrassias, 40
Winslow, foramen of, 827
Wirsung's canal, 882
Wisdom tooth, 783
Wolffian bodies, 992
Womb, 982. See UTERUS
Wormian bones, 55
Wrisberg, cartilages of, 908
ganglion of, 698
nerve of, 646
Wrist -joint, bones of, 83
ossification of, 90, 93
fascia of, 231
ligaments of, 142, 147, 231
movements of, 228
XIPHOID (£t<£os, a sword ; «8oy, shape)
process, 23
YELK, segmentation of, xv
Yellow cartilage, Ixxxv
fibres of areolar tissue, Ixxi
ligaments, 123
spot in retina, 726, 729
tissue, Ixxvi
ZONA denticulata, 764
glomerulosa, 939
pectinata, 763
pellucida, 990
reticularis, 939
Zones, abdominal, 823
Zonula Zinnii vel ciliaris, 736
f
Zygapophyses (&y, root of
yoke, or join together ; apophysis),
22
Zygoma (a cross-bar, or bolt, from root
above given), 36
Zygomatic arch, 36, 57
fossa, 57
Zygomatici muscles, 1 76
THE END.
BRADBURY, KVANS, AND CO., PRINTERS, WR1TKFR1ARS.
DATE DUE SLIP
UNIVERSITY OF CALIFORNIA MEDICAL SCHOOL LIBRARY
THIS BOOK IS DUE ON THE LAST DATE
STAMPED BELOW
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