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QUAIN'S

ELEMENTS OF ANATOMY

EDITED BY

EDWARD ALBERT SCHAFER, F.R.S.

PROFESSOR OF PHYSIOLOGY AND HISTOLOGY IN DNIVEKSITY COLLEGE, LONDON

GEORGE DANCER THANE,

PROFESSOR OF ANATOMY IN UNIVERSITY COLLEGE, LONDON.

IN THREE VOLUMES.

VOL IL— PART L

OSTEG LOG Y-ARTHRO LOGY.
By professor THANE.

ILLUSTRATED BY .224 ENGRAVINGS

B E P K I N T K D FROM THE

Cent!) eoitiou. (1896.)
Re-iaautd, with Arthroloyi/ added., and New index, 1899.

LONGMANS, GREEN, AND CO.

39 PATEKNOSTEli KOW, LONDON
NKW YOllK AND BOMBAY

18<)9

1/ -7'
BIBLIOGEAPHICAL NOTE.

Nintli Edition, 2 Vols., Svo. November, 1882; Vol. I. Beprrnted Marcli, 1884;
Odoler, 1887. Vol. II. Reprrnted December, 1883; April, 1887.

JVez'-' Edition, edited by E. A. Schdfer and G. D. Thane, in 8 separately issued
Parts and an Appendix, 1890-6.

Vol. II., Fart I. (Osteology) first separate issue, October, 1890. Reprirded February,
1893 ; November, 1896. With an Index.

Arthrology transferred from Vol. II., Part II., July, 1899, and New Index added.

{

CONTENTS OF PAET I.

DESCRIPTIVE ANATOMY.

OSTEOLOGY.

PAOB

The Skeleton and Bones generally 3
I. The Vertebral Column

Vertebrae .....

General Characters .
Groups of Vertebrae .

Cervical Vertebrae

Dorsal Vertebrae .

Lumbar Vertebrae

Sacral Vertebrae .

Coccygeal Vertebrae .
The Vertebral Column as a whole
Ossification of the Vertebrae .
Serial Homology of the Vertebrae
II. The Thorax ....
The Sternum or Breast- Bone
The Eibs ....

The Costal Cartilages
The Thorax as a whole
Ossification of the Sternum and

Ribs

III. The Boxes of the Head .

Occipital Bone

Parietal Bone ....
Frontal Bone
Temporal Bone
Sphenoid Bone

Ethmoid Bone ....
Superior Maxillary Bone
Palate Bone ....
Vomer .....
Malar Bone ....
Na.sal Bone ....
Lachrymal Bone
Inferior Turbinate Bone .
Inferior ^laxillary Bone
Hyoid Bone ....
The Skull ab a Whole
The Sutures

External Surface of the Skull
Interior of the Cranium .
Nasal Cavities and Communi
eating Air-Sinuses .
Ossification of the Bones of the
Head ....
General Morphology of the Bone.s
of the Head . . . '.
List of the Typical Component
Parts of the Bones of the
Heatl clas-sified according to
their Origin ....
Various Forms of Skull

IV. Bones of the Upper Limb .

Clavicle . ....

Scapula .....

Humerus
Ulna .
Radius .
Carpus .

Scaphoid Bone

Lunar Bone

Pyramidal Bone .

Pisifonn Bone .

Trapezium Bone .

Trapezoid Bone

Os Magnum .

Unciform Bone .
Metacarpus
Digital Phalanges
Ossification ot the Bones of the
Upper Limb
. The Pelvis and Lower Li mi?
Hip-bone

Ilium

Os Pubis

Ischium .
The Pelvis

Position of Pelvis

Difi'erences according to Sex
Femur. ....
Patella .
Tibia .
Fibula .
Tarsus

Calcaneum or Os Calcis

Astragalus

Navicular Bone

Cuneiform Bones

Cuboid Bone
Metatarsus ....
Phalanges ....
The Bones of the Foot as a whole
Ossification of the Bones of tli

Lower Limb

'toUPIIOLOGY of the BONES OF Til

Limbs ....
Relation to the Axial Skeleton
Homological Comparison of
Upper and Lower Limbs
Shoulder and Pelvic Girdles
Bones of the Limbs .
Hand and Foot
Tal)le of the Homologous Bones
in the Thoracic and Pelvic
Limbs . . . •
Carpus and Tarsus . .

Scapula and Ilium
Adaj)tation of the Skeleton to th*
Erect Attitiidf . ■

page
91
95
97

ICO
lOI
lOI
lOI

101
102
102
102

103
103
105

106
no
no
no
"3
"3
"5
117
nS
n8
124
124
127
129
129
130
13'
131
132
133
135
135

136

140
140

140
140
142
«43

144
144
145

145

IV

CONTENTS OF PART 1.

ARTHROLOGY.

The Articulations in General
Various Forms of Joints
Various Kinds of Movement

Articulations of the Trunk and Head 151

Articulations of the Vertebral Column
Articulations of the Atlas, Axis, and

Occipital Bone .
Articulations of the Thorax .
Temporo-Maxillary Articulation
Articulations of the Upper Limb
The Scapulo-Clavicular Arch .

Stern o-Clavicular Articulation

Scapulo-Ciavicular Articulation

Ligaments of the Scapula .
The Shoulder-Joint ....
Articulations of the Bones of the Fore

arm .....
The Elbow-Joint ....
The Wrist- Joint and Articulations of the
Carpus .

Radio-Carpal Articulation

Carpal Articulations .
Carpo-Metacarpal and Intermetacarpal

Articulations . . . . .

147
147
151

151

155
158
162
164
164
164
164
166
166

169
170

172

172
173

175

Metacarpo-Phalangeal and luterpha-
langeal Articulations .
Articulations of the Pelvis .

Articulation of the Pelvis with the last

Lumbar Vertebi-a .
Articulations of the Sacrum and Coccyx,

and of the Pieces of the Coccyx .
Sacro-Iliac Articulation
Sacro-Sciatic Ligaments .
Pubic Articulation
Articulations of the Lower Limb .
The Hip-Joint ....
The Knee-joint . , . .

Tibio-Fibular Articulations
The Anlde-Joint ....
Articulations of the Foot

Articulations of the Calcaneum, Astra

galus, and Navicular Bone
Calcaneo-Cuboid Articulation
Articulations of the Navicular, Cuboid

and Cuneiform Bones
Articulation of the Tarsus with the

Metatarsus ....

Intermetatarsal Articulations
Metatarso-Phalangeal and Interphalan
geal Articulations .

176

177

177

178
178
179
180
181
181

183
189
190
192

192
193

194

195
196

197

DESCEIPTIVE ANATOMY.

Descriptive Anatomy may be treated of in two methods : viz., the Systematic
and the Topographkal.

In the first or Systematic Anatomy, the several organs and parts of the body are
considered in a systematic order, according to their structure, their connection with
each other, and their relation to the purposes of life ; while in the second, or
Topographical Anatomy, the parts are described in the order of their position
or association in any region of the body. The first method is best adapted for the
elementary and complete study of the structure of organs, the second is more
immediately useful in the study of particular regions in their relation to Medicine
and Surgery. The object of the present work being mainly to serve as a guide for
systematic study, the topographical details will for the most part be included under
and combined with the general description of organs, and only some of the more
important regions will receive separate notice.

The plan of construction of the body and the general arrangement of its chief
parts have been explained in the Introduction at the beginning of Volume I. The
several systems and regions now to be described will be treated of under the following
heads : —

1. Osteology, the Bones.

2. Arthrology, the Articulations.

3. Myology, the Voluntary Muscles, with which will be combined the Fasciic and

Aponeuroses.

4. Angeiology, the Heart, the Blood-Vessels, and the Lynipliatics.

5. Neurology, the Spinal Cord and Brain, the Nerves, and the Organs of the

Senses.

6. Splanchnology, the Organs of Respiration, the Organs of Digestion, the

Urinary Organs, and the Organs of Reproduction.

7. Superficial Anatomy, and Topographical Anatomy of some Regions.

Descriptive terms. — In anatomical descriptions the body is always supposed
to be in the erect attitude, and terms of relation are employed strictly with reference
to this position. Thus, superior and inferior correspond respectively to cephalic and
caudal, anterior and posterior to ventral and dorsal. The body being bilaterally
symmetrical, it might be divided into similar and nearly equal halves by a vertical
plane directed from before backwards. This is known as the median plane, and the
line along which the median plane meets the surface of the body is called the middle
or median line. The words internal or mesial and external or lateral denote

2 DESCRIPTIVE ANATOMY.

respectively nearer to or farther from the median plane. Sagittal indicates a dorso-
ventral direction in or parallel to the median plane, and coronal ov frontal a direction
perpendicular to the foregoing in a transverse vertical plane. The terms superficial
and deep, central and peripheral, proximal and distal, are often used, and need
no explanation. In many cases precision may be obtained by reference to certain
fixed relations of parts, such as the vertebral and sternal ends of the ribs, the radial
and ulnar, or tibial and fibular borders, and the fiexor and extensor surfaces of
the limbs. Preaxial and postaxial, applied, for instance, to parts of the hmb,
signify, respectively, on the primitive cephalic or caudal aspect of the axis of
the member.

OSTEOLOGY.

By G. D. THANE.

THE SKELETON.

The skeleton or solid framework of the body is mainly formed of the bones, but
is completed in some parts by the addition of cartilages. The bones are bound
together by means of ligaments, and are so disposed as to support the softer parts,
protect dehcate organs,, and give attachment to the muscles by which the different
movements are executed.

In the lower animals the term skeleton has a wider signification than in man,
comprehending two sets of parts, viz., 1st, those of the endoslceleton, or the deeper
osseous and cartilaginous framework which corresponds to the human skeleton ; and
2nd, those of the exosJcekton, or dermal sicelefon, comprising the integument and
various hardened structures connected with it. All vertebrate animals possess an
endoskeleton ; but in some of them the exoskeleton attains greater proportions
than in others, and is combined by means of hardened parts more fully with portions
of the endoskeleton. In most invertebrate animals the dermal or exoskeleton alone
exists.

In man, as in the higher vertebrates, the greater part of the endoskeleton is
formed of bone, a calcified animal tissue, which, when freed by putrefactive macera-
tion from its fat and various soft adherent parts, and subsequently dried, is capable
of remaining unchanged for a very long period of time. It is customary and con-
venient thus to study the bones chiefly in the macerated and dried state, that is,
deprived of their accessory soft parts.

The accessory soft parts connected with the fresh bones consist chiefly of the
external fibrous and vascular covering termed perioskum, and of the medulla,
marrow or fat, which fills their larger internal cavities. The bones are permeated
by blood-vessels, and they are provided also with absorbent vessels and with nerves
in small quantity.

The ends of the bones, when jointed moveably with others, are covered by a thin
layer of dense permanent cartilage, called articular cartilage; and the adjacent
bones are united together by fibrous ligaments which may be considered as con-
tinuous with the periosteum covering the rest of the bones. In some instances
distinct bones are directly united by means of ligament or cartilage without any
joint-cavity intervening. Thus the osseous system as a whole may be considered to
be enveloped by a fibrous covering.

The bones are originally formed by a process termed ossification from soft sub-
stance. This process commences in the greater number of bones in cartilage ; in
some it begins in fibrous tissue or membrane ; and in all instances the farther
growth of the bone substance takes place largely in the latter way. The deposit of
Ijone begins generally at one spot, which is therefore called the primary centre of
ossification ; but there may be several of these from the first. The main part of the
bone thus formed from the primary centre is sometimcB named the diuphysis. In
most Ixjnes, after considerable advance in growth by extension from the primary

II 2

4 OSTEOLOGY.

centre, ossification occiirs at comparatively later periods in one or more separate
points, forming secondarij or tertiary centres ; and the portions of bones so formed,
which remain united to the main part for a time by intervening cartilage, are termed
epiphyses. In many instances entire consolidation of the bone by the osseous union
of the epiphyses does not take place till the full size has been attained, and this may
be as late as the twenty-third or even the twenty-fifth year of life.

In their outward form the bones present much diversity, but have been reduced
by anatomists to the following classes : — 1. Long or cylindrical, such as the chief
bones of the limbs. These consist of a body or shaft, cylindrical or prismatic in
shape, and two extremities which are usually thicker than the shaft, and have smooth
cartilaginous surfaces for articulation with neighbouring bones. The shaft is
generally hollow and filled with marrow, by which sufficient size and strength are
attained without undue increase of weight. 2. Tabular or flat bones, like the
scapula, ilium, and the bones forming the roof and sides of the skull. 3. Short
bones, which are more or less cubical or oblong, as in the carpus and tarsus.
4. Irregular or mixed bones, mostly situated symmetrically across the median plane
of the body, and often of a complex figure, such as the vertebrae.

In these differently shaped bones the osseous substance occurs in two forms, viz., the
compact and the spongy. There is, however, no essential difference in structure or properties
between these beyond that of thickness or thinness of the component material.

The surfaces of bones present various eminences, depressions, and other marks, to designate
which the following terms are in common use. Any marked bony prominence is called a
process or apophysis ; a slender, sharp, or pointed eminence is named a spine, or spinovs
process ; a blunt one a tiiiercle ; a broad and rough one a tuberositij. The tenns crest, line,
and ridge are usually applied to a prominent border, or to an elevation running some way
along the surface of a bone. A head (caput, capitulum, or capitellum) is a rounded process
usually supported on a narrower part named the tiech (cervix). The term condyle, somewhat
variously applied by anatomists, is most frequently employed to denote an eminence bearing
a rounded articular surface.

The cavities and depressions of bones are very variously named. An apertm'e or perfora-
tion, when short, is b> foramen ; when continued some way as a passage it is a canal or
ineatus. A narrow slit is a fissure, an open excavation or hollow in one bone or in several
together is a fossa. This term is also sometimes applied to the socket of a joint, as in the
glenoid or shallower, and the cotyloid or deeper form of joint-cavity. Sl?ms and antrum are
names applied to considerable cavities in the interior of certain bones. Besides these, various
other terms are employed which do not require explanation, such as 7iotch (incisura), groove,
furrow (sulcus), &c.

The number of bones in the skeleton varies at different periods of life, some
which are originally distinct becoming united together as the process of ossification
advances. The following is a statement of the number usually reckoned as distinct
in middle life : —

{ The vertebral column

Axial
Skeleton.

Appendicular
Skeleton.

J The skull

1 The hyoid bone

^ The ribs and sternum

f The upper limbs

1^ The lower limbs

Single bones.

Pairs.

Total

. . .26

26

. ' . 6

8

22

. 1

1

. 1

12

25

32

64

31

62

34

83

200

Besides the bones included in the above enumeration, there exist likewise the three
pairs of auditory ossicles, and various bones formed in tendons and called sesamoid,
the most constant of which are, besides the patella and pisiform bone, reckoned m
the table above as limb-bones, a pair iu each thumb and great toe.

THE VERTEBRAL COLUMN.

SPINOUS PROCESS

P ARTIC.PROCF.SS

I.— THE VERTEBRAL COLUMlSr.

The vertebral columu is composed of a series of bones called vertdmc, which are
united together, for the most part, by joints and elastic substance in such a manner
that, although the anionnt of motion allowed between each pair is slight, the
aggregate is sufficient to give the column very considerable flexibility. The vertelrcz
are originally thirty-three in number. Of these, the upper twenty-four remain
separate in the adult, retaining their mobility, and are hence called movcaUe or true
vertebrae. They are succeeded by five others, which rapidly diminish in size from
above downwards, and which are united into one mass called the sacrum ; beyond
the sacrum are four dwindled terminal members of the series, which as age
advances, likewise become more or less united, and form the cocc//x. These sacral
and coccygeal vertebrae are known as the fi.red or false vertebra.

General characters of the vertebrae. — The general characters are best seen
in the vertebra? placed near the
middle of the column, of which
the tenth dorsal vetebra, shown
in fig. 1, may serve as an example.
Each has more or less the form of
a ring, and presents for considera-
tion a body, arch, processes, and
the enclosed spinal foramen.

The bod// or centrum is a short
cylinder or disc, which forms the
anterior part of the vertebra. Its
superior and inferior surfaces are
flattened and connected to the
next vertebras by strong and elas-
tic intervertebral discs. On the
front and sides it is convex hori-
zontally, but slightly concave
from above downwards ; its pos-
terior surface forms part of the
ring, and is slightly concave from
side to side. These vertical
surfaces are pierced by numerous
small foramina for the passage

of blood-vessels, and near the middle of the posterior surface are one or two much
larger than the others.

The arch (neurat) consists of two symmetrical portions which spring, one on each
side, from the posterior surface of the body, and meet in the median plane behind.
The anterior i)art of each half, thick and narrow, is called the petficte ,- the jiosterior
part is broad and fiat, and is called the lamina. The concavities on the ui)per and
lower borders of the pedicles are named rerleljral nolrlies (fig. 2, B), and (;onsti-
tute, by the apposition of tliose of contiguous vertebrae, the inlrrrcrletrral foramina,
a series of rounded apertures, which communicate with the vertebral canal, and
transmit the spinal nerves and blood-vessels.

'J'he spinous process (neural spine) projects backwards IVoiii the :ir(;li in the
median plane. The transverse processes, placed one on each side, i»iv)jcct outwards
from the arch at the junction of the ))edicle with the lamina. The articular pro-
cesses (zygapophyses), two superior and two inferior, project upwards and downwards
opposite the attachment of the transverse processes ; their articular surfiices, coated

Fix. L

-Tenth dorsal vertebra, from above.
I))' D. (jiinn.)

(Drawn

6 THE VERTEBRAL COLUMN.

with cartilage, in the superior jmir look backwards, and in the inferior forwards, so
that the former face the latter in adjoining yertebrge.

The foramen is bounded anteriorly by the body, posteriorly and laterally by tho
arch. The series of riiigs thus formed, united by ligaments, constitutes the spinal
or neural canal, which lodges the spinal cord.

Texture. — The bodies of the vertebras are almost entirely composed of spongy substance,
the principal lamella being' vertical ; on the surface is a thin layer of compact tissue.
Venous canals, commencing at the larger foramina behind, traverse the cancellated structure.
The arch and processes contain a much smaller proportion of spongy substance, being covered
with compact tissue of considerable density in some places.

GROUPS OF VERTEBRiE.

The vertebrse are divided into five groups, named from the regions which they
occupy, cervical, dorsal, lumlar, sacral, and coccygeal.

Cervical vertebree. — These are seven in number ; they are the smallest of the

moveable vertebrae, and are spe-
cially characterized by the pre-
sence of foramina in the trans-
verse processes. The first and
second are so peculiar in form,
as to require a separate descrip-
tion. The following are the
common characters of a cervical

INF. ARTIC.PROC.

SUP. ATTIC. PROC.

vertebra.

POST. TUBERCLE
GROOVE FOR NERVE
ANT. TUBERCLE

INF. ARTir
PROCESS

IMF. VERTEBRAL NOTCH

Fig. 2. — Fourth cervical vertebra : A, from above
B, PROM THE RIGHT SIDE. (Drawn by 1). Gunn. )

The hocly is small, and much
broader from side to side than
from before backwards ; in depth
nearly the same in front and
behind. Its upper surface is trans-
versely concave from the upward
projection of its lateral margins,
and is sloped down in front. The
under surface, on the contrary,
is rounded off at the sides, while
its anterior margin forms a marked
projection downwards.

The pedicles spring from the

body about midway between the

upper and lower borders, and are directed outwards and backwards ; the lamince are

slender, long and flat. The superior and inferior notches are nearly equal in depth.

The spinous process is short, only slightly depressed, and bifid.

The iranverse iirocesses are short, and present at their extremities two tubercles,

anterior and posterior. Each process is deeply grooved above for a spinal nerve, and

its base is perforated vertically by a round foramen (vertebrarterial), through which

in the upper six the vertebral artery and vein pass. It is united with the rest of the

vertebra by two parts ; by the posterior, at the place of junction of the pedicle and

lamina, like a dorsal transverse process ; by the anterior, to the body of the vertebra,

in the same position as the heads of the ribs.

The articular processes are placed at the extremities of a short, stout, vertical
column of bone ; their 'articular surfaces are nearly flat and obhque, the superior
looking backwards and upwards, the inferior forwards and downwards.

THE FIRST CERVICAL VERTEBRA. 7

The foramen is tviaugular, with rounded angles, and larger than in the dorsal or
lumbar vertebra?.

The first cervical vertebra, (ir atlas, differs remarkably from the others in
the absence of a body and siiinous process, having the form merely of a large ring
with articular and transverse processes.

The interior of the ring is wider behind than in front. Its posterior part cor-

ODONTOID PROCESS

TRANSV. PROC.

TRANSV. PROO.
Mr. ARTIC. PROCESS

Fig. 3. — Atlas and axis, froji before. (Drawn by D. Grunn.)

responds to the foramina of the other vertebrjE ; its narrower anterior part is
occupied by the odontoid process of the axis, and in the recent state is separated
from the posterior by the transverse ligament. In front of the ring is the anterioi
arch, on the anterior aspect of which is a small tubercle, and on the posterior a
smooth surface for articulation with the odontoid process. At the sides of the ring
are the lateral masses, which are thick and strong, Ijearing the articular processes
above and below, and extending outwards into the transverse processes. The articular

POSTERIOR ARCH

VERTEBRAL GROOVE

SUP. ARTIC. PROC.

TUBERCLE FOR TRANSV.
LIGAMENT
ANTERIOR ARCH

ARTIC. SURF. FOR ODONTOID PROC.

Fig. 4. — Atlas, from above. (Drawn liy D. Gunn.)
The position of the tran.sver.se ligament is inclicatcil by dotted line.s.

processes differ from those of other vertebrae in being situated in front of the places
of exit of the nerves. The superior, larger than the inferior, are oval, and converge
in front ; their articular surfaces are concave for the reception of the condyles of
the occipital bone, and look upwards and inwards ; they are frequently divided by a
transverse groove into two. Below the inner margin of each, towards the front, is a
smooth rounded tubercle, to which the transverse ligament is attached. The inferior
articular processes are smaller than the superior, flat, nearly circular, looking down-
wards and slightly inwards.

The posterior arch presents in the middle line a rough elevation, tlu; rudiment of
a spinous process ; at its junction with the lateral masses, it is hollowed out above

8

THE VEETEBEAL COLUMN.

SO as to form a smooth transverse groove — the vcrfetral groove, in which he the verte-
bral artery and first spinal (suboccipital) nerve ; the groove corresponds to the
superior notches of the other vertebrge.

The transverse processes are larger and project farther outwards than those of the
subjacent vertebrae. They are flattened from above downwards, and have a large
foramen. Their extremities are not bifid, but broad and rough.

Varieties. — The posterior arch of the atlas is sometimes imperfect, the gap in the bone
being bridged across by a fibrous band. A similar defect in the anterior arch is comparatively
rare, but its complete absence has been observed.^ The transverse process, especially the
anterior bar, may also be the seat of defective ossification, and the foramen of the vertebral
artery is then completed by ligament. A bony arch over the vertebral groove is frequently met
with. Less common is the formation of a canal for the vertebral artery on the outer side of
the superior articular process.

The second vertebra or axis (vert, dentata) forms a pivot on which the
first vertebra rotates carrying the head.

The tody is characterized by the presence of a large blunt tooth-like process called

ODONTOID PROCESS

Fig. 5. — Axis, from the right side.
by D. Gunn.)

(Drawn Fig. 6.-

-Seventh cervical a'ertebra, from
ABOVE. (Drawn by D. Gunn.)

odontoid (proc. dentatus). This consists of an enlarged part termed the head, and a
lower part or neck. It has in front a smooth surface for articulation with the
atlas, and behind a smooth groove to receive the transverse hgament. The lower
surface of the body resembles that of the succeeding vertebrge. Its anterior surface
is marked by a low median vertical ridge, with a depression on each side.

The superior «rf/f«/«r surfaces, placed like those of the atlas in front of the notch,
lie close to the base of the odontoid process, partly on the body and partly on the
pedicles of the vertebra. These surfaces look upwards and slightly outwards. The
inferior articular processes are similar in form and position to those of the succeeding
vertebrae.

The spinous process is very large, rough, deeply bifid, and grooved on its inferior
surface. The Jamince are very thick and strong.

The transverse processes are short, and the anterior tubercle almost obsolete. The
foramen for the vertebral artery is inclined obliquely upwards and outwards.

The seventh cervical vertebra has a long spinous process, which is not
bifurcated, but ends in a broad tubercle projecting under the skin, whence the name

' Dwiglit, Journ. Anat., xxi, 539.

THE DORSAL VERTEBRiE.

FACETS FOR SIXTH RIB

of vertehra prominens has been
given to this bone. The transverse
processes are massive, and only
sUghtly grooved, with a small fora-
men ; their posterior tubercle is
large and prominent, while the
anterior is but faintly marked.

In most cases the spinous process of
the sixth cei-\-ical vertebra is also un-
divided : and in the dark races of man
the spinous pi-ocesses of the thii'd, fouith
and fifth vertelnaj are more frequently
simple than bifid. (D. J. Cunningham,
Jouru. Anat., xx. C37.)

Dorsal or thoracic vertebrae.

— These are twelve in number, ard
support the ribs.

The hodij as seen from above is
somewhat heart-shaped ; its antero-
posterior aud transverse diameters
are nearly equal : its dejjth is greater
behind than before.

It is specially characterized by
the presence, at the place where it
joins the arch, of articular surfaces
for the heads of ribs. In the greater
number of instances there are two
costal surfaces on each side, — one at
the upper, the other at the lower
border, — so placed that each com-
pletes, with that of the adjacent
vertebra, a cavity for the head of
one rib.

The Jamhice, broad and flat, are
imbricated or sloped one pair over
another like tiles on a roof. The
superior notches are very shallow,
the inferior deep.

The spinous jrroccss, described as
bayonet-shaped, is three-sided, and
terminates in a slight tubercle. It
is longest and has the gi'eatest
downward inclination in those to-
ward the middle of the series.

The transverse processes are
strong, directed outwards and back-
wards, and terminate in a imigh

knob which presents anteriorly a smooth surface for articulation with the tuberosity
of a rib.

The crrtkular processes have their cartilaginous sui faces nearly vertical. Those
of the superior processes look backwards, slightly upwards and outwards ; those of
the inferior look forwards, slightly downwards and inwards.

FACET FOR SEVENTH RIB
INFERIOR VERTEBRAL NOTCH
INFERIOR ARTICULAR PCOCoSS

Fig. 7. — Sixth dorsal vertebra : A, froji

ABOVE ; B, FROM THE RIGHT SIUE.

(Drawn by D. Gunn.)

Fig. S. — First dorsal vertebra, from tiii: right
SIDE. (Drawn by D. Gunii.)

10

THE VERTEBRAL COLUMK.

The foramen is nearly circular, and is smaller than in ttie cervical or the lumbar
region.

The first, tenth, eleventh, and twelfth dorsal vertebrge present certain characters
by Avhich they may be individually distinguished.

The first dorsal vertebra in its general conformation approaches very closely

MAM. PROC
TRANSV. PROC
ACCESS. PROC

Fig. 9. — Ninth, tenth, eleventh, and twelfth dorsal, and first lumbar vertebra, from
THE right side. (Drawii by D. Gunu.)

the seventh cervical. The body is elongated transversely and concave on the upper
surface ; the superior vertebral notches are of considerable depth ; the upper articular
surfaces are oblique ; and the spinous process is long and nearly horizontal. On
each side of the body is a circular facet close to the upper border for the first
rib, and a very small facet below for the second.

The tenth dorsal vertebra touches only one rib on each side, and has a
single nearly complete articular surface, mainly on the pedicle. There is usually
a small facet on the transverse process.

THE LUMBAR VERTEBR.^.

11

The eleventh dorsal vertebra has a complete articular surface on each side
for the head of the ril), but no facet on the transverse process.

The twelfth dorsal vertebra has also only a single facet on each side ; the
inferior articular processes have their surfaces turned oiitwards, resembling those of
a lumbar vertebra ; the transverse processes are short and present three elevations,
the external, superior, and inferior taherdes, which correspond to the transverse,
mamillary, and accessory processes of the lumbar vertebraj. Indications of these
tubercles may cften be seen also \\\m\ the tenth and eleventh vertebrae.

Varieties.— The ninth dorsal vertebra frequently wants the lower facet on the side of the
body. The tenth dorsal vertebra sometimes has no facet on the transverse process. The
chanjre from the dorsal to the lumbar type of articular processes occasionally takes place
between the eleventh and twelfth dorsal vertebra;.

Lumbar vertebrae. — These are five in number, the largest of the moveable
vertebrie, and are distinguished by the absence of costal articular surfaces.

The hodu has a greater diameter transversely than from before backwards, ^

IMF ARTICULAR PROC.

MAMIL-UARY PROC.
/ACCESSC^V PROC

TRA^5VEPSE PROC.

SLP ARTICUL-AP PROC.

Fig. 10. — TniHi) LUMBAii vERTEDRA, FRi'M ABOVE. (Drawn by D. Gunn.)

and viewed from above or below its surface presents a reniform outline ; the depth is
generally slightly greater in front than behind.

The lamimc are shorter, deeper, and thicker than those of the donsal vertebrje.
The superior notches arc shallow, the inferior deep.

The .spinous process projects horizontally backwards. It has considerable breadth
from above downwards, and is thickened and rough along its posterior edge.

The transverse p-ocesses, slender and somewliat spatula-shaped, project directly
outwards ; they are shortest in the first, longest in the third vertebra. Their
extremities lie in series with the external tubercles of the lower dorsal transverse
processes, and with the ribs. Behind each at its base is a small process pointing
downwards, which corres]}onds to the infei'ior tubercle of the dorsal transverse
process, and is called the accessoi // process (atiapophysis).

The articutar processes arc tliick and strong. Their articular surfaces are vertical ;

12

THE VERTEBRAL COLUMX.

the superior, concave, look backwards and inwards; the inferior, convex, look forwards
and outwards. The superior pair are farther apart than the inferior, and embrace
the inferior pair of the vertebra above them. From each superior articular process
a tubercle projects backwards, which corresponds to the superior tubercle of the
dorsal transverse process, and is called the mamillary process (metapophysis).

T\iQ foramen is large and triangular, or widely lozenge-shaped.

The fifth lumbar vertebra is massive, the body is much deeper in front than
behind, the transverse processes are broad and conical, the lower articular processes
are wider apart than the upper, and the laminas project into the spinal foramen on
each side.

While in the European the bodies of the lumbar vertebrte are collectively deeper in front
than behind, in conformity with the curvatiu-e of this part of the column, the individual

Fig. 11. — Fifth lumbar vertebra, feom above. (Drawn by D. Gunn.)

segments show some difference in this respect. Thus, the first lumbar vertebra is deeper
behind than in front ; in the second the anterior and posterior vertical diameters are nearly
equal ; and the third, fourth and fifth are characterized by a preponderance of the anterior
depth, which increases proo'ressively from above downwards. In the dark races of man
(Australian, Bushman, Andamanese, Negro) the depth of the five lumbar bodies together is
greater behind than in front, and the fifth is the only one in which the anterior depth notably
exceeds the posterior. It does not appear probable, however, that this conformation of the
vertebral bodies is accompanied by a less marked degree of lumbar curvature, since the latter
is determined mainly by the intervertebral discs. (W. Turner. Journ. Anat., xx, and
•' Challenger " Reports, Zoology, xvi ; D. J. Cunningham, " The Lumbar Curve in Man and
Apes." Dublin. 1886, and Proc^ Roy. Soc, 1889.)

"Varieties in number of the moveable vertebrae. — The number of the cervical vertebrEe
is remarkably constant. The dorsal and lumbar vertebra may vary reciprocally, the total
remaining the same, according to the number of ribs present. Thus, if there are only eleven
pairs of thoracic ribs, the twelfth vertebra will have lumbar characters: while in the more
frequent case of a thirteenth pair of ribs being developed, the corresponding vertebra might
be regarded as dorsal, although, in general conformation, it usually more resembles the
lumbar tyjDe. The whole number of true vertebrae may be diminished or increased by one.
In the former state the first sacral vertebra will be the 2ith. as is the case generally in the
Orang, and, if the number of the ribs remain normal, there will be only four lumbar vertebrse.
In the case of increase, the first vertebra to articulate with the hip-bone will be the 26th, and

THE SACRAL VERTEBRA.

13

there may be twelve dorsal and six lumbar vertebrae, or thirteen dorsal and five lumbar.
Sometimes an intermediate or transitional form is met with, as in the so-called lumhu-sacral
vertebra, in which one side is united to the sacrum. Avhile the other has a free transverse
process (fi?. 23. 11) ; such a vertebra may be the 2-tth or 2oth. The study of the development
of the vertebral column throws litiht on the orio-in of these varieties. It appears from the
researches of Rosenberg- that in the foetus the 2(Jth vertebra is oris'inally the first sacral, and
that in the course of g-rowth the hip-bones move headwards so as to become attached
also to the 2oth. which consequently becomes incorporated in the sacrum. This shiftintr
may proceed farther, so that the 2-l:th vertebra is included : or it may be unsymmetrical.
givinjr rise to a lumbo-sacral vertebra. Similarly, a thirteenth rib arises from the
persistence and growth of a cartilaii-inous rudiment which is regularly present in the
embryo, but usually becomes incorporated in the transverse process of the first lumbar
vertebra. (J. Struthers. •• Variations of Ribs and Yertebraj."" Joum. Anat., ix ; P. Topinard,
"Anomalies de nombre de la colonne vertebrale."' Rev. d"Anthropol., 1877; E. Rosenberg-,
" Pmtwickelung- der Wirbelsiiule," Morph. Jahrb.. i.)

SUP. ARTtC.

Fig. 12. — The sacrum, from before. (Drawn by D. Gunn.) |

Sacral vertebrae. — These by their union in the adult fovm the os sacrum, but
in youth they pi'esent the elements of live distinct vertebra. The sacrum is placed
below the last lumbar vertebra, and articulates laterally with the two hip-bones,
thus completing, together with the coccy.x, the wall of the pelvis above and behind.
The uppermost vertebra is the largest, those which follow become rapidly smaller, and
the fifth is rudimentary. Hence the sacrum has the form of a triangle with its
bfi.se directed ujjwards. It is concave and smooth in front, convex and uneven
behind. The direction of its surfaces is very oblique, its ventral aspect looking
considerably downwards, and forming above, at the place where it joins the last
lumbar vertebra, the projection termed the promoniorij. The dorsal or posterior
surface looks upwards as well as backwards.

Tlie ventral surface is conca\e from above downwards, and slightly so from side

14

THE VERTEBRAL COLUMN.

to side. It is traversed horizontally by four ridges, which indicate the places of
union of the bodies of the five sacral vertebras, and at the extremities of which are
situated on each side four foramina called anterior sacral. These foramina lead
externally into grooves, and diminish in size from above downwards.

The dorsal surface is convex, very uneven, and somewhat narrower than the
ventral. It presents along the median line three or four small eminences, the
spinous processes, usually more or less connected, so as to form a ridge. Below the
spinous process is a triangular opening, the termination of the spinal canal, the
lateral margins of which are formed by the imperfect laminae of the fourth and fifth
sacral vertebrae, and are produced downwards into a pair of tubercles, the sacral

UPPER APERTURE OF £3ACRA1_ CANAL
/SUP. ARTIC. PROC.

DEPRESSIONS
FOR POSTERIOR
SACRO ILIAC
UICAMEINTS

POST. SAC. FORAM.

ACPAU COBNU
iLoVv/ER APERTURE OF" SACRAL. CANAL.

Fig. 13. — The sacruji, fhom bkhind. (Drawn by D. Gunn.) ^

cornua, which represent the inferior articular processes of the last sacral vertebra,
and are connected to the cornua of the coccyx. On each side of the ridge of spines
the surface formed by the united laminee is slightly hollowed, thus giving rise to
the sacral groove, which j^rolongs the vertebral groove of the moveable part of the
column ; and beyond this are the four posterior sacral foramina, opposite to, but
smaller than the anterior. Immediately internal to each foramen is a slight
eminence, w^hich represents the articular and mamihary processes of the vertebras
above, while external to the foramen a more strongly marked elevation corresponds
to the transverse process.

The part of the sacrum external to the foramina constitutes the lateral mass, and
is broad and thick above, but narrowed below. The outer aspect of the upper part
presents in front a large uneven surface, covered in the recent state with cartilage,
which articulates with the ilium, and is called from its shape the auricular surface :
behind this the bone is rough and marked with strong depressions for the attachment
of hgaments. Lower down^, the margin becomes narrowed and sinuous, terminating in

THE SACRAL VERTEBRA.

15

the projection called the inferior lateral amjle, below which the breadth of the bone
is suddenly contracted so as to form a notch with the adjacent part of the coccyx.
The base, or upper surface of the first sacral vertebra, bears considerable

resemblance to the
upper surface of
the last lumbar
(fig. 23, 9 and 10).
In the middle it
presents the reni-
form surface of
the body, behind
which is the tri-
"'' angular aperture
of the sacral canal,
bounded by the
depressed lamina3.
On each side of the
aperture is an arti-
cular process, simi-
lar to the superior process of a lumbar vertebra, but
of large size, and bearing a well-developed mamillary
process. In front of this is a groove which forms with
the lower notch of the last lumbar vertebra an inter-
vertebral foramen. The external portion of the base
presents posteriorly an eminence ^corresponding to the
lumbar transverse process, and in front of that a
triangular smooth surface, continuous with the iliac fossa
of the hip-bone, and known as the ala of the sacrum.

The lower end or apex, formed by the small inferior
surface of the body of the fifth sacral vertebra, is trans-
versely oval, and articulates with the coccyx.

The sacral canal is curved with the bone, and gra-
dually narrows as it descends ; in transverse section
it is three-sided above, but flattened and rather semi-
lunar below. It terminates on the posterior surface of
the bone between the sacral cornua, where the laminas
of the last two sacral vertebrae are
imperfect. From this canal there
pass outwards in the substance of
the bone four pairs of interverte-
bral foramina, closed externally
by the lateral masses, but opening
ou the surfaces by the anterior
and posterior sacral foramina.

Tlie sacrum of the female is
broader in proportion to its length,
and asually Hatter than that of the
male ; but the curvature vaiies
•,'reatly in different nkeleton.s.

The Hacrum of man is charac-
terized by its great breadth in comparison with its lenjxbh.

Fig. 14. --Sacrum and

FROM THE RIGHT SIDK.

bv D. (iunn.) '4

COCCYX,

(Drawn

Fig. 15. — Transverse section ok sacrum, passing

THROUOH THE FIRST PAIR i>K I'liRAMINA. ((t. D. T. ) I

This

the micrul huh-.r, which is
Urvera-'c sacral index in tlio

proportion is expressed by

^, „ ,, . , 1 i.- 1<*" X breadth „,

asceitained l)y the following calculation, ; . The

length

male European is 112, in the Nc-rro IOC, in the Australian !)!),

16 THE VERTEBRAL COLUMN.

and in the i^ndamanese 94. In the European female it is about 116. The anthropoid apes
have a sacral index varying from 87 in the orang- to 72 in the gorilla. (Turner, Journ. Anat., xx.
and '• Challenger" Reports, Zoology, xvi.)

Varieties. — The sacrum not unfrequently consists of six pieces, a condition which is
g'enerally due to the inclusion of the first coccygeal vertebra. More rarely there are only four
sacral vertebrEe. Occasionally the bodies of the first and second vertebra are not united,
though complete union has taken place in every other part ; or the first vertebra may present
on one side the usual sacral form, while on the other it has the form of a lumbar vertebra, and
is not united to the next (see fig. 23, 11, Z'), a peculiarity connected with the oblique form of
pelvis. Instances also occur in which it presents, on both sides, characters intermediate
between those of sacral and lumbar vertebree. The sacral canal may be open below to a
greater extent than usual ; it has even been found open throughout.

Coccygeal vertebrse, coccyx. — These are very rudimentaiy vertebrse,
commonly four, sometimes five, seldom only three in number. The first of the
series is considerably broader than the others. It presents superiorly, on the part
corresponding to the body, an oval concave surface, which articulates with the lower
end of the sacrum. From its posterior surface two small processes, termed cornua of

Fig. 13. —The coccyx : A, from behind; B, froji before. (Drawn by D. Gunn.) f

tJie coccyx, project upwards ; they represent the pedicles and superior articular
processes of the vertebrEC generally, and are connected at their extremities to the
sacral cornua, with which they enclose an aperture — the last intervertebral foramen
(fig. 14) for the passage of the fifth sacral nerve. On each side the short transverse
process projects, and usually bounds, with the lowest part of the lateral margin of the
sacrum, a notch for the anterior division of the same nerve ; but in some cases it is
united by bone to the lower lateral angle of the sacrum, so as to form a fifth anterior
sacral foramen.

The remaining three coccygeal vertebrse are much smaller than the first.
The second piece, when separate, has upper and lower flattened surfaces for
articulation with the vertebi"^ above and below ; on each side is a rudiment of the
transverse process in the form of a slight tubercle ; and on the posterior aspect there
may sometimes be seen two small eminences in series with the cornua of the
first piece, and representing the last traces of a neural arch. The third and fourth
pieces are mere rounded nodules, slightly compressed from above downwards, and
corresponding solely to vertebral bodies. In middle life the first piece is usually
separate, while the three lower pieces are united into one, the original separation
being indicated by transverse grooves.

In advanced life the coccygeal vertebrfB, having been previously joined into one
bone, may become also united to the sacrum. This union occurs at an earlier age
and more frequently in the male than in the female, but it is subject to much
variation. The first piece often joins the sacrum before the union of the rest of the
bone.

THE VERTEBRAL COLUMN AS A WHOLE.
ci

17

^.

v-

Ll

AP,

A

>b",

.-c*

COl

0

p

SI

.%^

Col

Fig. 17. — Vektebral column of an adult male,
FitoM BEHIND. (Allen Thorn.son.) ^
(' 1, firet cervical vei-tebra ; D 1, first dorsal vertebra;
L 1, first lumbar vertebra; S 1, first .sacral vcrtci)ra; CO 1,
first cwcygeal vertebra. The transition in tiic form of the
tranBverKe proceKKes and tuliercicH in the lower dorsal and
first lumbar vertebra i.s well marked in this specimen.

Fig. 18. — Veutebual column, from
TUK LEFT SIDE. (Allen Thoiuson. ) J

The letters and numbers indicate tlio
several vertebne. The .antero-postcrior
curves of the column are shown, together
with the shape and size of tlic vcrtebrsB
and intervertebral spaces.

18 THE VEHTEBRAL COLUMN.

According to the observations of E. Steinbach there are in most cases five coccygeal
vertebrae in the male, four or five with about equal frequency in the female. (" Die Zahl der
Caudalwirbel beim Menschen," Diss., Berlin, 1889.)

The vertebral column as a whole. — The vertebral column may be regarded as a
central axis upon which the other parts of the skeleton are arranged. Superiorl)
it supports the skull, laterally the ribs, through which also it receives the weight of
the upper limbs, and near its lower extremity it rests upon the hip-bones, by which
the weight of the body is transmited to the lower limbs. It is a pillar of support to
the rest of the skeleton, and protects the spinal cord by enclosing it in a bony
canal. Its average length is about 28 inches in the male, 27 inches in the female.

When seen in profile the column presents four curves, directed alternately for-
wards and backwards, — forwards in the cervical and lumbar regions, backwards in
the dorsal and sacral. The upper curves pass imperceptibly into one another, but
nfc the junction of the last lumbar vertebra with the sacrum a considerable angle is
formed, known as the lumbosacral or sacro-vertebral angle, causing the promontory
to overhang the cavity of the pelvis. The dorsal and sacral, curves are primary
curves affecting those parts of the column which enter into the formation of the
bony-walled cavities, the thorax and pelvis ; they make their appearance at an early
period of foetal life, and are due to the conformation of the vertebral bodies : the
cervical and lumbar curves are secondary or compensatory curves, necessary to the
upright posture, only developed after birth, and dependent mainly on the shape of
the intervertebral discs ; in these regions also the principal movements of the spine
take place. The curves obviously confer upon the column greater elasticity and
security from injury than it would have were it perfectly straight. In the upper
dorsal region there is also very frequently a shght degree of lateral curvature, the
convexity of which, in most cases, is directed towards the right side, and which is
probably connected with the greater use made of the right than of the left arm.

Viewed from the front, the bodies of the vertebrse are seen to become broader
from the axis to the first dorsal, then slightly narrower to the fourth dorsal, and
from this vertebra they gradually widen to the base of the sacrum. The width
between the extremities of the transverse processes is considerable in the atlas ; small
in the axis, it becomes greater as far as the first dorsal vertebra ; thence it is again
gradually contracted as far as the last dorsal, and becomes suddenly much greater in
the lumbar region.

In the lateral view, the antero-posterior diameter of the bodies increases in de-
scending through the dorsal and lumbar regions.

Viewed from behind, the spines occupy the middle line. On the sides are the
vertebral grooves, corresponding to the laminge, and bounded externally in the cer-
vical and dorsal regions by the transverse processes, and in the lumbar by the
mamillary processes. Along each groove is a series of spaces between the laminae,
which, in the natural condition, are filled up by the yellow ligaments. The extent
of these intervals is very trifling in the neck and in the greater part of the back ;
it increases in the lower third of the dorsal, and still more in the lumbar region.
The interval between the occipital bone and the arch of the atlas is considerable,
and so is that between the last lumbar vertebra and the sacrum.

The only part of the vertebral column that appears on the surface of the body
is the row of spinous processes, and these are subcutaneous from the seventh cervical
to the third sacral. The upper cervical spines are deeply placed and can be felt with
difficulty in the median interval between the muscular masses of the back of the
neck ; the sixth is sometimes long and in such cases may project. The seventh
cervical and the following one or two dorsal spines are prominent ; the others lie at
the bottom of the long spinal furrow produced by the eminence of the spinal muscles
on each side.

i

OSSIFICATION OF THE VERTEBRAE.

19

OSSIFICATION OP THE VERTEBRA.

The vertebrae in general. — The ossification of each vertebra proceeds in cartilaije from
three principal centres, one for the main part of the body, and one on each side for the arch
and processes, together with a small part of the body. The lateral centres appear about the
7th week of foetal life, that of the body very soon afterwards. From these centres the
ossification extends gradually, so as to form the greater part of the vertebra. The central
ossification does not pass, however, in the dorsal vertebras the place of articulation of the head
of the rib. but leaves on each side a portion of the body which is formed from the lateral
ossification, and is separated up to the third year by a narrow cartilaginous interval — the
neiiro-cmtral Kiinrhiinilrnxi.i. It v.'ould appear farther, that while ossification in the arches
commences first in the cervical vertebras, the osseous centres of the bodies appear earliest in
the lower dorsal vertebras.

At the time of birth most of the vertebras consist of three osseous pieces, corresponding to
the three original centres. In the first year of infancy the laminas of opposite sides become
united in a number of the vertebras, but not in all. The spinous processes, remaining

Fig. 19.

-Ossification of the vertebrje.
(R. Quain.)

1,

A, fietal vertebra, showing the three primary centres ;
2, neural ossitications ; 3, ceutral ossification.

B, dorsal vertebra from a child of two years ; 1 & 2
are seen to have encroached upon the body at * the
neiiro-central synchondrosis, to have extended into the
articular and transverse processes, and to have united
behind in the spinous process, leaving tlie ends cartila-
ginous.

C, dorsal vertebra at about seventeen years, showing
epiphyses on the transverse processes, 4 & 5, and
spinous process, 6, and the ujiper epiphysial plate of
the body, 7.

D & E, parts of a lumbar vertebra of about the same
age, showing, in addition to the foregoing, 8, the lower
epiphysial plate of the body ; 9 & 10, the epiphyses of
the mamillary tubercles.

cartilaginous for a time, are gradually completed by the gi'owth of the cartilage and the
extension of the bone into them, and at the same time, by the ossific extension of the
transver.se processes and other parts, the vertebras gradually attain to nearly their full size and
shape about the age of puberty. At different periods subsequent to this, five epiphyses, or
supplementary centres of ossification, are added. Three of these are small portions of bone.
placed on the tips of the ."ipinous and transverse processes : the other two are thin annular
plates on the upper and lower surfaces of the body at its circumference. In the lumbar
vertebra) two other epiphyses surmount the mamillary processes. These epiphyses appear from
the sixteenth to the twentieth year, and are not wholly united to the rest of the vertebra
before the twenty-fifth year. The transverse process of the first lumbar vertebra is sometimes
develope<l from a separate centre. The anterior divisions of the cervical transverse processes
are for the most part ossified by the extension into them of osseous substance from the
neighbouring posterior part of the process and from the arch ; but there are usually separate
osseous nuclei for those of the seventh, sometimes also of the sixth, and even the fifth or
second vertebrie.

Atlas and axis. — The ossification of the atlas and axis differs considerably from that of

Fig. 20. — OssiFiCATiu.s' OF TJiE ATLAS. (R. Qualn.)

A, before birth ; IJ, in the first year ; 1 iV 2, lateral
''enires of cssification ; Z, ossific centre in the anterior
arch.

the other vertebras. In the atla.s the anterior arch is formed by a strip of cartilage in which
osf-ification, commencing by one or two centres, only appears in the course of tlie first year
after birth. The posterior arch, together with the lateral masses, is formed from two centres

0 2

20

THE VERTEBRAL COLUMN.

whicli con-espond to the neural ossifications of the other vertebr;©, and which begin to ossify-
about the seventh week. Their union posteriorly occui-s in the third year, and is frequently
preceded by the formation of a distinct spinal nucleus. Their union with the anterior arch
does not take place till the fifth or sixth year.

In the axis, the arch and processes are formed from two centres corresponding to those of
the other vertebrse, and appearing about the seventh or eighth week. Ossification begins in

Fig. 21. — Ossification of the axis. (R. Quain.)

A, from a fcetiis of seven months ; -3, centre for the body;
4, 5, two centres in the base of the odontoid process.

B, shortly after birth ; 1, 2, neural ossifications : 3,
central ossification ; 6, odontoid ossification.

the body about the fourth month, from one or sometimes two centres, occupying the lower
part of the common cartilage of the body and odontoid process. In the upper part of this
cartilage, a little later, two collateral centres appear for the odontoid process ; these soon unite
into one, so that at birth the axis is composed of four pieces of bone. About the fourth year
the odontoid process becomes joined to the body and the fore part of the neural arch of the
axis on each side, and a little later union occurs in front and behind". In the centre,
however, a small disc of cartilage remains until advanced age.^ The apex of the odontoid
process is formed from a distinct centre which appears in the second year, and joins about the
twelfth year. There is the usual annular epiphysis on the lower surface of the body.

Sacral vertebrae. — Each of the sacral vertebrse has three primary centres of ossification,
one in the body and a pair in the arch. The centres of the bodies of the first three vertebrae
appear about the eighth or ninth week, those of the two following vertebra somewhat later.

Fig. 22. — Ossification of the sacrum. (E. Quain.)

A, sacrum of a foetus before six months seen from the front, showing the ossific centres in the
bodies of tlie vertebrte.

B, at birth ; 2, 2, additional centres for the lateral masses.

C, about twenty-three years ; 3, 3, epiphysial plates still visible above and below the first vertebral
body ; 4, 4', latei-al epiphysial plates.

D, upper surface of first sacral vertebra at four or five years ; 1, and 2, as in A and B. (Allen
Thomson.)

A & B, nearly full size ; C, one-fourth ; D, one-third.

The laminse begin to ossify about the sixth month, but the time of union with the bodies
differs in the different vertebrae, taking place as early as the second year in the lowest, but
not till the fifth or sixth year in the uppermost. In each of the first three vertebra (sometimes
however only in two, sometimes in four) the anterior part of the lateral mass on each side is
formed from an additional nucleus which appears at the outer margin of the anterior sacral
foramen from the sixth to the eighth month. These unite to the bodies later than the arches.
In the case of the lower two vertebra the lateral masses are formed by extension of
ossification from the primary lateral nuclei. On the body of each vertebra epiphysial plates
are formed after puberty, as in other vertebrae ; and two irregular plates of bone are added on
each, side of the sacrum, the uppermost of which extends over the auricular surface,, and the

^ D. J. Cunningham, Journ. Anat., xx, 238.

SERIAL HOMOLOGY OF THE VERTEBRA. 21

lower over the sharp edge below. These appear from the eighteenth to the twentieth year,
and are united about the twenty-fifth. The bodies of the sacral vertebrae are at first separated
by intervertebral discs, but about the eighteenth year, in the case of the lower vertebra,
ossification begins to extend through these discs and the epiphyses, so as completely to unite
the adjacent bodies. The ossific union of the first and second bodies does not take place till the
twenty-fifth year or later. Previous to this, the lateral masses have coalesced in the same
order as the bodies.

Coccygeal vertebrae. — Each of the coccygeal vertebrae is ossified from a distinct piece o'
cartilage, and usually from a single centre, but in the upper sometimes from two centres.
Ossification commences in the first generally about the time of birth ; in the second, from the
fifth to the tenth year ; in the third, some time before, and in the fourth, some time after
puberty. The ossific union of the three lower coccygeal vertebrae occurs before middle life ;
their union with the first, and the union of this with the sacrum, belong to the later periods
of life.

Variations may occur in the mode of ossification of the vertebree, as is shown by the nature
of certain malformations. Thus, instances are recorded in which a vertebral body is
represented by two pieces of bone, separated by a median interval : here ossification must
have proceeded from two centres, as is the case normally in the odontoid process, and
sometimes in the body of the axis : probably this is the reappearance or persistence of a
primitive condition. Similarly, the neural arch of the fifth lumbar vertebra (very rarely of
one of the other vertebrse) may have a double origin, being divided by a cleft passing
obliquely between the superior and inferior articular processes : according to Rambaud and
Renault ' there are always two nuclei in each half of the neural arch.

SERIAL HOMOLOaY OF THE VERTEBRiE.

It is evident from the foregoing descriptions that the different segments of the vertebra!
column are generally similar in construction ; and this similarity is for the most part so
marked that there can be no doubt of the homodynamy of the several constituent parts of
successive vertebrae. In certain instances, however, there are peculiarities of arrangement
which offer some difficulty in tracing the precise correspondence, and in explanation of these
chiefly the following brief sketch of the serial homology of the vertebras is given. The
accompanying views of the vertebrae and some of their varieties (fig. 23) will also assist the
reader in comparing theii- forms.

1. The series of centra or bodies, surrounding the primary axis of the notochord, la
complete in man, from the odontoid process of the second vertebra to the caudal extremity.
It must, however, be remembered that the part called the body of a vertebra includes not only
the proper central ossification, but also the ventral extremity of the neural ossification on each
side. The body is apparently absent in the atlas, but the part corresponding to the central
ossification of that vertebra is united with the body of the axis in the odontoid process ;
while the anterior arch of the atlas probably belongs to the series of subcentral parts or
hypapophyscs. The proofs of this view are derived mainly from, 1st, the remains of the noto-
chord having been traced in the foetus through the odontoid process (and not through the
anterior arch of the atlas) into the base of the skull ; 2nd, the separate ossification in cartilage
of the odontoid process ; and .Srd, the existence in some animals, as the ornithorhynchus and
some reptiles, of a bone con-esponding to the odontoid process, in a separate condition, without
any other jjart representing the centrum of the atlas.

2. The series of neural arches is complete in the whole vertebral column of man, with
the exception of the lower three coccygeal vertebrae, and in part of the first coccygeal and
lower sacral vertebrae. The neural spines are also complete in nearly the same vertebrai as
the arches. The spine is absent or little developed in the atlas, bifid at its extremity in the
next four or five cervical vertebrae, but simple in all the remaining vertebrae in which it is
present.

3. The articular processes or zyg-apophyses, superior and inferior (preaxial and
postaxial), correspond in their relations throughout the whole of the vertebrae in which they
exist, with the exception of both of tliose of the atlas and the superior of the axis. In these
vertebrae the articular processes are not in the series of zygapophyses, being situated in front
of the place of exit of the spinal nerves, instead of behind it, and therefore in a position
which corresponds to that of the part of the vertebral body formed from the neural ossifica-
tion. The joints which they form must accordingly be looked upon as homologous with the
lateral portions of the articulations between the bodies of the succeeding vertebrae. In the
sacral vertebiai the articular processes, existing as such in early life, come to bo in the adult
united by anchylosis. In the lower three coccygeal vertebras they are absent.

' "Origine et Developpement des Os," Paris, 1864. This work may be referred to for more detailed
information concerning tiie ossification of the vortebraa, as well as of t,hp bones generally.

2Z

THE VERTEBRAL COLUMN.

Fig. 23. — Views of different vERTEBKiE from above to illustrate their homologies
AND SOME OF THEIR VARIETIES. (Allen Thomson.)

1, atlas ; 2, axis : 3, fifth cervical ; 4, seventh cervical with supernumerai-y ribs : 5, middle dorsal ;
6, first dorsal, with costal arch and sternum attached ; 7, third lumbar ; 8, first lumbar with supernu-
merary ribs ; 9, fifth lumbar ; 10, first sacral ; 11, lumbo-sacral vertebra ; 12, fourth saci'al vertebra in
a young subject ; 13, four coccygeal vertebrte. In the several figures the parts are indicated by letters
as follows, viz , in 1, s, spine ; n, neural arch ; c', the space occupied by the odontoid process, or dis-
placed centrum ; h. anterior arch ; ar, superior articular process ; in 2, c", odontoid j^rocess ; ar, superior
articular surface ; z', inferior articular process : in 3, c, centrum ; z, z', superior and inferior articular
processes : in 4, t, transverse pi'ocess ; r, vertebrarterial foramen ; co, moveable right supernumerary or
cervical rib ; x, with a dotted line marking the place where an anchylosed rib on the left side may be
considered to be superadded to the transverse process of the vertebra : in 5, t, transverse process with

SERIAL HOMOLOGY OF THE VERTEBRA. 28

costal facet ; cc, costo-central facet : in 6, v, vascular interval; cl, costo-transverse, and cc, costo-ceutral
articulations ; co, first rib : in 7, m, mamillary, and a, accessory tubercles ; t, tra,nsverse process : in 8,
CO, co', supernumerary ribs : in 10, I, lateral mass : in 11, I', place of tlie lateral mass, remaining
undeveloped in this instance : in 12, tl, the transverse process and lateral ma-s which unite witli tl-.e
corresponding parts above;/,/', anterior and posterior sacral foramina thus formed : in 13, c, the
centrum, which alone remains in the lower coccygeal vertebrae.

4. It is in the comparison of the parts known in human anatomy under the general name
of transverse processes that the main difficulty of establishing- homologies exists. In the
cervical vertebris the processes so called are pierced by a vertebrarterial foramen, and
most of them have two tubercles. Those of the dorsal vertebrae are for the most part simple,
ijut articulate with the tubercles of the ribs, whence they are known in comparative anatomy
as the tuiercular 2)''occsses (diapophyses). At the place of articulation ot the head of the rib
with the vertebra there is in some animals a projection, called the cnj)itnlar ^;7v»c<'s*
(parapophysis) ; this is represented in man only by the articular facet on the body, which is
separated however from the proper central ossification by the neuro-central synchondrosis.
It is generally admitted that the part of the cervical transverse process in front of the verte-
brarterial foramen cori'esponds to the first part of a rib, as is illustrated by the separate o.=sification
of that piece of bone in the seventh cervical vertebra in man, and by the occasional occurrence
of a more fully developed cervical rib in that situation (fig-. 23, 4).

In the lumbar vertebree the transverse processes are elongated laterally, and at their root
two other processes become apparent, viz., the mamillary or metapopliysis directed preaxially,
and the accessory or anaj)02>hi/.sis, directed postaxially. Several circumstances in the anatomy
of the bones and muscles indicate that the outer part of the lumbar transverse processes is
serially homologous with the first part of the ribs, but so intimately combined with both
capitular and tubercular processes, and the part lying between them, as to leave no arterial
passage. This view receives confirmation from the presence of a costal element in connection
with the transverse process of the first lumbar vertebra in the foetus, and its occasional
development to form a supernumerary rib (p. 13 ; fig. 23, S).

In the sacral part of the column still greater departure from the form of the transverse
process of the upper vertebrae takes place by the large development and ossific union of the
lateral parts. Throughout the whole five vertebrae recognised as sacral in man, this may be
looked upon as occurring to some extent in portions of the bones which are serially
homologous with the combined capitular and tubercular processes ; but in the upper sacral
vertebrce, another element is interposed between the transverse process and the iliac surface
of articulation, constituting the greater portion of the lateral mass of the sacrum. This
element is generally regarded as serially homologous with part of a rib, and those vertebrae
which are thus connected to the ilium by means of a costal element are distinguished as true
sacral, the remaining anchylosed vertebrae being called 2Js<-'udo-sacral.

With the exception of the anterior arch of the atlas already referred to, there are no parts
developed in the human skeleton coiTesponding to the hypaiyopliyses which occur in connec-
tion with the vertebral column of animals, such as the "chevron" bones below the caudal
vertebra of cetacea, and the haemal arches enclosing the main artery of fishes.

II.— THE THORAX.

The skeleton of the thorax consists of tlie dorsal vertebrae already described, the
sternum, the ribs, and the costal cartiiag'es.

THE STERNUM OR BREAST-BONE.

The sternum is situated in the median line at the fore part of the thorax. lb
is connected with the rest of the trunk by the cartilages of the first seven ribs on
each side ; and at the upper end it gives attachment to the clavicles. It consists
originally of six segments. The first of these usually remains separate from the
rest, and i.s called the manuhriwn : the succeeding four are united into one in the
adult, and form the body : the sixth generally remains cartilaginous for some years
after birth, and often partially so even to advanced age, constituting the ensiform
process; in middle life it is most frequently united by bone to the body.

The sternum is flattened from before backwards, and presents a slight longitudinal
curve with the convexity in front. It is of unequal width, being broad at the upper
part of the manubrium, considerably narrower at the lower end of tliat portion and

24

THE THORAX.

B

WTERCLftVI CULAR NOTCH

CLAVICULAR nOTCI-1

BODY

,;^!;;^

IVIAMUBRIUIVI

t^'.

ENSIFORW! PROCESS

Fig. 24. — The sternum: A, from before ; B, from the left side. (Drawn by D. Gunn. ) f
The Roman numerals indicate the articular surfaces for the corresjDonding rib-cartilages.

in the first segment of the body, somewhat wider near the lower end of the body, and
finalJy narrowed at the junction with the ensiform process. It consists of light can-
cellated tissue, with a thin covering of compact bone.

The manubrium {'presternum) is the thickest part of the bone. Its anterior surface
presents a slight median elevation ; its posterior surface is smooth and somewhat con-
cave. Its upper border is divided into three deep notches ; the middle one is named

THE STERNUM OR BREASTBONE. 25

che mcisura semilunaris, or interclavicular notch ; the lateral ones form two depressed
articular surfaces, directed upwards, outwards and backwards, for articulation with
the clavicles, and called the clavicular notches. Each lateral border presents supe-
riorly, close to the clavicular notch, a rough triangular surface, which unites with
the cartilage of the first rib. Below this the bone slopes inwards, and at its inferior
angle presents a small surface, which with a similar one on the body forms a notch
for the cartilage of the second rib. The lower margin is straight and united by
cartilage to the upper margin of the body.

The body {gladiolus, mesosternwn) is marked on its anterior surface by three
slight transverse elevations at the lines of junction of its four component parts. Its
posterior surface is comparatively smooth. Each lateral margin presents five notches
for the reception of costal cartilages, and a small surface above, which, with the
similar depression on the manubrium, forms the notch for the second costal cartilage.
The notches for the third, fourth, and fifth costal cartilages are opposite the lines of
junction of the four segments of the body of the sternum ; those of the sixth and
seventh are placed close together on the sides of the inferior segment, that for the
seventh being completed by the ensiform process.

The ensiform or xiphoid process {melasternum, xiphisternum) is a thin
spatula-like process projectmg downwards between the cartilages of the seventh
ribs. It is subject to frequent varieties of form, being sometimes bent forwards,
sometimes backwards, often forked, and occasionally perforated.

The sternum is subcutaneous in the middle line, forminrr the floor of the sternal
groove between the pectoral muscles, which cover the lateral portions of the anterior
surface. The upper end is marked by the deep suprasternal notch; and the ensifitrm
process lies at the bottom of the infrasternal depression, the latter being due to the
prominence of the body and the seventh costal cartilages beyond the surface of the
ensiform process.

The length of the sternum and the proportions of its parts differ somewhat in the two
sexes. In the male the body is as a rule slightly more than twice as long as the manubrium ;
while in the female the whole bone is relatively shorter, and the body is usually less tlian
twice the length of the upper segment. Individual variations are, however, frequent and groat.
<M. Strauch, Diss., Dorpat, 1881 ; T. Dwight, Joum. Anat., xv, 327, and xxiv, 527; F. Peter-
moller, Diss., Kiel, 1890.)

Varieties. — The sternum is subject to many varieties of form. It is not unfrequently
much shorter than usual, and indented at its lower part, as occurs especially from the pressure
of the cobbler's last. Occasionally the lower part of the body is perforated by the so-called
tternal foramen (fig. 30, E) ; and in rare cases the sternum has been found divided to a
greater or less extent, constituting the malfoi-mation of fissura sterni, and connected in some
instances with ectopia cordis.

Two small nodules of bone, ossa Kupraxternalia, have been found in some rare cases at the
upper border, close to the clavicular notches, united by cartilage and ligament to the sternum.
Their position is indicated by the asterisks (**) in figure 30, E. They appear to be vestiges of
the episternal bone of monotremata and lizards, the lateral parts of which are represented
normallj- in the interarticular fibro-caitilages of the sterno-clavicular articulations.

THE RIBS.

The ribs (costce), twelve in number on each side, constitute a series of arched
and highly elastic bones, which extend outwards and forwards from the vertebral
<x)lumn, and form the lateral walls of the thorax. Their anterior extremities give
attachment to cartilaginous prolongations — the costal cartilages, the first seven pairs
of which pass inwards to the sternum. On this account the first seven pairs of ribs
are called sternal, also true, and the remaining five pairs asternal or false ribs. Of
'hese asternal ribs, each of the upper three has its cartilage attached along its superior
border to the cartilage of the rib above it ; while the two last are entirely free from
such attachment, and are thence c-dWad floating ribs.

26

THE THORAX.

General characters of the ribs. — These are best marked in the ribs near the
middle of the series. The posterior extremity is tliickened, and is termed the head

TUBEROSITY
NON-ARTICULAR PAR"

ARTICULAR FACE

SUBCOSTAL CROOVE-

or capitulum ; it presents a superior and an inferior
obhque articular surface for articulation with the
bodies of two vertebra, and, between them, a slight
ridge, to which the interarticular ligament is attached.
At a little distance from the head, and separated from
it by the slightly constricted neck, is the tuherositij,
an oval eminence which is divided into two parts by
an oblique groove ; the inner part is smooth and
articulates with the transverse process of the lower of

Fii{. 26.

-Fifth kib op the eight side, froji behind.
(Drawn by D. Gunn.) J

y

the two vertebra with which the head is connected,

while the outer part is rough and serves for the

attachment of the posterior costo-trans verse ligament.

The whole extent beyond the tuberosity constitutes

the body. It is laterally compressed, and broader

iTom above downwards towards the anterior extremity.

Outside the tuberosity, over the most convex part of

ihe body, is a rough line which corresponds to the

outer border of the erector spinse muscle, and marks

the angle, so called because at this point the rib takes

a more sudden curve, its direction being now forwards

and outwards. The inferior border presents on its

inner aspect the subcostal groove, in which lie the

intercostal vessels and nerve, and Avhich is best

marked opposite the angle and disappears in front.

The anterior extremity of each rib is hollow'cd at its tip into an oval pit, in which

the costal cartilage is implanted.

Inclination and curves. — There is a general inclination of the ribs downwards
from the head to the anterior extremity, the slope being greatest between the head

Fig. 25. — Fifth rib of the right-
side, FROM BELOW. (Drawn by
D. Gunn.) 5

THE RIBS.

:7

and angle. The curve of the ribs is more marked towards the back part than in
front, especially near the angle. Besides the main curves now mentioned, the rib
is slightly twisted on itself, so that while its surfaces are vertical behind, they are
placed somewhat obliquely in front.

Special characters of certain ribs. — The ribs increase in length from the
first to the seventh or eighth, and decrease to the twelfth, so that the last is little

EMIINJEMCE FOR SERRATUS MAGNUS

Fig. 27. — First and second ribs of the right side, from above.
(Drawn by D. Gunii.) 5

longer, often even shorter, than the first. The first rib is the broadest, and after nt
the middle ones ; the twelfth is the narrowest. The distance of the angle from
the tuberosity increases gradually from above down.

The first rib is not twisted, and is so placed that its surfaces look nearly upwards
and downwards. The head is small, and presents a single articular surface for the
first dorsal vertebra. The neck is slender, and the angle coincides with the
tuberosity. On the superior surface are two slight smooth depressions with an
intervening rough mark, and a considerable rough surface behind. The rough
surface marks the attachment of the scalenus medius muscle, the posterior depression
the position of the subclavian artery, the anterior depression the subclavian vein ;
and the intervening slight elevation, frequently terminating in a sharp spine on the
inner edge — the scalene iuherch — indicates the attachment of the scalenus anticus
mu.scle. There is no subcostal groove on the first rib.

The second rib, longer than the first, presents externally a prominent roughness
which marks the attachment of the serratus raagnus.

In the eleventh and twelfth ribs the articular facet on the head is single, and
the tuberosity is represented only by a slight elevation or roughness, without an
articular facet. The subcostal groove is faintly marked on the eleventh, and is
absent, together with the angle, from the twelfth.

Varieties. — The number of the ribs is sometimes increased to thirteen on one or both
sides. The supemumerarj' rib is u.sually short, and is most frequently formed in connection
with the transverse process of the first lumbar vertebra, or occasionally v/ith the seventh
cervical : in the latter case the additional rib has generally a double attachment, viz., to the
body, and to the tran.sverse process of the vertebra outside a vertebrarterial foramen (see
fitr. 23, 4, r, V, and 8, cu). In rare instances the additional rib is associated with a
thirteenth dorsal vertebra (see p. 1.3). The tenth rib frequently articulates only with

28 THE THORAX.

one vertebra; and it may want the articular facet for the transverse process. The
twelfth rib varies in length from 8 inches to less than an inch ; complete suppression
is very rare.

Fig. 28. — Tenth, eleventh, and t^velpth ribs op the right side, from below.
(Drawn by D. Grunn. ) j

The costal cartilages prolong the ribs towards the sternum. Their breadth
diminishes gradually from the first to the last, while their length increases as far as
the seventh, after Avhich they become gradually shorter. Their line of direction
varies considerably. The first descends a little, the second is horizontal, and all the
rest, except the last two, ascend more and more from the rib towards the sternum as
they are situated lower down. The external or costal extremity, convex and uneven.

THE THORAX AS A WHOLE.

29

is implanted into and united with the end of the coiTespondin"- rib. The internal
extremities of the cartilages of the true ribs (except the first, which is directly united
to the sternum without articular cavity) are smaller than the external, and fit into the
corresponding notches on the side of the sternum. Each of the cartila.ges of the first
three false ribs becomes slender towards its extremity, and is attached to the lower
border of that which is next above it. The eleventh and twelfth are pointed and
unattached. The fifth, sixth, se\euth, aud eighth cartilages form a series of inter-
chondraJ arficulaiions, by means of a broad process sent down from the rounded ano-le
of the one meeting a less salient projection from the upper border of the next.

Varieties. — The eig^hth corital cartilage not unfrequently articulates with the sternum.
Occasionally the seventh costal cartilage fails to reach the mesosternum (owing to reduction
of the latter), and meets its fellow in front of the ensiform process. The articulation
between the fifth aud sixth cartilages is sometimes wanting, and then one may be formed
between the eighth aud ninth.

THE THORAX AS A WHOLE.

The bony thorax is of a somewhat conical shape, flattened from before back, and
much longer behind than in front. The posterior wall, formed by the dorsal

Fig. 29. — Front view of the thor.^x.

1. manubrium ; 2, is close to the place of union of the
fii"st costal cartilage; 3, clavicular notch ; 4, body of the
sternum : 5, ensiform process ; 6, groove on the lower
border of the ribs ; 7, the vertebral end of the rilis ; 8, neck ;
9, tuberosity; 10, cos'.al cartilage; 12, first rib; 13. its
tuberosity ; 1-1, first dorsal vertebra ; 15, eleventh rib ; 16,
twelfth rib.

vertebrae and the ribs, is convex from above

down, and, the ribs being directed backwards

from the vertebrte as far as their angles, a broad

furrow is produced on each side of the spines, which

lodges the erector spinte muscle. The anterior

wall, formed by the sternum and costal cartilages,

is only slightly convex, and is inclined at an

angle of 20° to 25° with the vertical. In the

condition of expiration the upper border of the

sternum is opposite the disc between the second and third dorsal vertebrae, the

junction of the manubrium and body opposite the middle of the fifth dorsal vertebra,

and the xiphi-sternal articulation about opposite the interspace between the ninth

aud tenth dorsal vertebrae.

The sides are sloped outwards to about the ninth rib, are slightly convex from
above down, and strongly arched from before back. The upper aperture is-
contracted, reniform, nearly plane, and much sloped downwards ; the lower is
irregular ; the margin ascends on each side from the tenth rib to the xiphi-sternal
articulation, arid thus gives rise to the subcostal angle, in the centre of which the
ensiform process projects. The foi'm of the cavity corresponds generally to that of
the exterior, but in the median plane the antero-posterior diameter is much reduced
by the projection of the bodies of the vertebra} ; as a consequence of this and the
backward direction of the hinder ends of the ribs, a deep hollow is formed on each
Bide, into which the posterior portions of the lungs are received, and thus the weight
of the body is thrown farther back and is more equally distributed ai'ound the
vertebral column.

3U

THE THOEAX.

The intercostal spaces are eleven in number, and somewhat wider above than
below, but varying with the elevation or depression of the ribs.

In man the transverse diameter of the thorax exceeds the antero-posterior. whereas in
quadrupeds the dorso-ventral diameter is usually the g-reater. In the human foetus also the
sagittal diameter preponderates, and at the time of birth it is but little less than the
coronal. In the female the thorax is relatively shorter, and more rounded than in the male.

OSSIFICATION OF THE STERNUM AND RIBS.

The ossification of the sternum begins about the sixth month, and usually by a single
centre in the manubrium. The next centre appears at the seventh month in the upper

If

Fig. 30. — OssiFiCATio>' OF THE STERNUM. (R. Quaiu.)

A, the cartilaginous sternum before the middle of fcetal life.

B, the sternum at birth. 1, 2, 3, & 4, the nuclei for the manubrium and upper three pieces of the
body.

C, the sternum soon after puberty, showing cartilage between the manubrium and body, and
imperfect union of the iirst, second and third pieces of the body, while the third and fourth are
united.

D, a sternum at birth ■with an unusual number of ossific centres, six in the manubrium, 1', which
is very uncommon ; two pairs in the lower pieces of the body 3' & 4', which is not unusual ; 2, the
•single centre of the first piece of the body.

E, Example of perforated sternum ; this figure also shows two suprasternal bones, * *. C and E
are reduced below the size of nature.

segment of the body, and ossification follows in the next two segments shortly before birth. ■
In the lower segment ossification begins in the first year or later, in the xiphistemum usually
not before the sixth year, and often much later. In the manubrium there are sometimes two

Fig. 31.- — One of the middle ribs

AT ABOUT TWENTY YEARS OF AGE.

(E. Quain.)

1, body ; 2, epiphysis of the head ;
3, that of the tuberosity.

centres of ossification, one above the
other, and occasionally several ai-e
met with. In the upper segment of
the body the centre is most commonly
single, but in each of the following
segments there are frequently two,
placed one on each side of the middle
line. The lower segments of the body unite together after puberty, but the upper one often
remains separate till after the twenty-fifth year. The xiphisternum is united to the body in
middle life ; the manubrium and body are only exceptionally joined by bone. The bony
parts formed from the lateral centres of the lower segments of the body not unfrequently

THE BONES OF THE HEAD. 31

remain separate for a considerable time, and occasionally, by defect of ossification or non-
union across the middle line, leave the permanent median aperture referred to on p. 2.5.

The ossification of the ribs begins in cartilage posteriorly about the eighth or
ninth week of foetal life, and extends rapidly forwards, so as to reach the permanent
cartilage about the fourth month. After puberty the centres of two small epiphyses appear
in the cartilage of the head and tuberosity. These become united with the main bone by the
twenty-fifth year. The epiphysis of the tuberosity is wanting in the eleventh and twelfth.

In the adult the first costal cartilage usually becomes the seat of a superficial ossification,
which may proceed so far as to form a complete sheath around it ; and in advanced life the
other cartilag'es are frequently more or less covered by bone, especially on their anterior
surface. The tendency to bony deposit is as a rule stronger in the male than in the female,
but the age at which tlie ossification begins, and the extent to which it proceeds, are subject to
great variation. The cartilage itself is but seldom ossified.

III.— THE BONES OP THE HEAD.

The skull, comprising the bones of the head, is of a spheroidal figure, compressed
on the sides, broader behind than before, and supported on the vertebral column.
All its bones, with the exception of the lower jaw, are immoveably united together
by lines and narrow surfaces, more or less uneven, termed sutures. The skull is
divided by anatomists into two parts, the cranium and t\i& face. The cranium pro-
tects the brain ; the face surrounds the mouth and nasal passages, and completes
with the cranium the orbits or cavities for the eyes. The cranium is composed of
eight bones, viz. : the occipital, two jJarietal, the frontal, two temporal, the sphenoid,
and the ethmoid. The face is composed of fourteen bones, of which twelve are in
pairs, viz. : the superior maxillarji, malar, nasal, palate, lachrymal, and inferior
turbinate hones ; and two single, viz. : the vomer, and the inferior maxilla. The
hyoid hone, suspended by ligaments from the under surface of the cranium, may also
be classed with the bones of the head.

THE OCCIPITAL BONE.

The occipital bone is situated at the lower and back part of the cranium. In
general form it is flattened and lozenge-shaped, with the longest diameter directed
from behind, forwards and downwards. It is much curved, so that one surface is
concave and looks forwards and upwards, while the other is convex and looks back-
wards and downwards. At the lower and fore part it is pierced by a large oval
aperture, the occipital foramen ov foramen magnum, which forms the communication
between the cranial cavity and the spinal canal. The portion of the bone behind
the foramen is tabular, the narrower part in front forms a thick mass named basilar
process, and the parts on the sides of the foramen, bearing the condyles or articu-
lating processes by which the head is supported on the atlas, are the condylar
portions.

The two superior borders are deeply serrated, and articulate with the parietal
bones in the lambdoid suture. By its two inferior borders, which are uneven but
not deeply serrated, it articulates with the mastoid and petrous portions of the
temporal bone ; while the extremity of its basilar process is united to the body of
the Bfihenoid, in the young condition by cartilage, but after the age of twenty years
by continuous osseous substance. The rhombic form generally given by the meeting
of these borders at the four angles is not unfrequently somewhat changed to the
octagonal, by the projection of subordinate obtuse angles between the upper and
lateral, and between the lateral and lower angles.

The tabular portion, on \ifi, posterior surface, presents about the centre a promi-
nence— the external occipital protuhera7ice, from which i\\Q superior cti7'ved line arches
outwards on each side towards the lateral angle of the bone, thus dividing the

3£

THE BONES OF THE HEAD.

surface into two parts, an upper and a lower. The protuberance varies greatly in
its development in different skulls ; when well marked it can be readily felt beneath
the skin at the back of the head. A little above the superior curved line there may
generally be seen the less distinct highest curved line ' ; and between the two is a
narrow semilunar area in which the bone is denser and smoother than either above
or below. The part of the surface above this is regularly convex, and is covered by
the hairy scalp. The lower part is more uneven : it is divided into two lateral
portions by a median ridge called the extertial occipital crest; and each of these is

^XT. OCC.PHOT.

HIGHEST CURVED LIME

SUP CURVED LINE

IMF. CURVED LIME

POST.COND. FOR.

PHARYNC. TUB.

BASILAR PBOC.

Fig. 32. — Occipital bone, fkom below. (Drawn oy D. Gunn.) f
On tlie left siJe a probe is passed througli the anterior condylar foramen.

again divided into an upper and a lower surface by the inferior curved line, which
can be followed outwards to the extremity of the jugular process. The curved lines
and the areas thus marked out give attachment to the numerous muscles of the back
of the neck.

Along the highest cnrved line the epicranial aponeurosis is fixed to the bone. To the
upper curved line are attached, internally the trapezius, and externally parts of the occipitalis,
sterno-cleido-mastoid, and splenius capitis muscles. Below the upper line is a large impression
for the complexus ; and more externally, immediately above the outer part of the lower line,
is a smaller mark where the obliquus capitis superior is inserted. The inferior curved line
forms the upper limit of two impressions, the inner one for the rectus capitis posticus minor,
and the outer one for the rectus posticus major. To the lower part of the protuberance and
the external occipital crest the ligamentum nuchae is attached.

The deep surface of the bone is marked by two smooth ridges w^hich cross one
another, one extending from the upper angle to the foramen magnum, and the other
transversely between the two lateral angles ; at the point of intersection of these

1 F. Merkel, " Die Linea nuchse suprema. " Leipzig, 1871.

THE OCCIPITAL BONE.

33

ridges is the internal occipital pro t a be ranee. Separated by the ridges are four hollows,
the superior and inferior occipital fossfc, which lodge respectively the posterior
cerebral and the cerebellar lobes. The superior part of the longitudinal and the
transverse ridges are grooved in the course of the longitudinal and lateral venous
sinuses respectively. The wider space where the longitudinal groove is continued
into one of the lateral grooves (more frequently the right) by the side of the internal
occipital protuberance lodges the torcular Herophili. The inferior part of the

o;>:g. SULCUS

SUP. OCC. FOSSA

INT. OCC. PROT.

INF. OCC. FOSSA

LAT. SULCUS

JUG.PRQC.

UG. NOTCH
POST COND. FOR.

F. PETR. SULCUS

BASILAR PROC.

Fig. 33. — Occipital bone, from before. (Drawn by D. Gunn.) ^

longitudinal ridge is sharp, and is named the internal occipital crest. The margins
of the tabular portion are deeply serrated above the lateral angles for articulation
with the parietal bones ; below that level, they unite with the mastoid portions of
the temporal brmes.

The condylar portions bear the articulating condyles on their lower part, close
to the margin of the foramen magnum in its anterior half. The condyles are
elliptical, and converge somewhat in front ; their surfaces are conve.v from behind
forwards and from side to side, and somewhat everted. On the inner side of each
is a rough impression for the attachment of the lateral odontoid ligament of the
axis. Perforating the bone at the base of the condyle is the anterior condylar
foramen, running from the interior of the cranium immediately above the foramen
magnum outwards and forwards, and transmitting the hypoglossal nerve. Behind
the condyle is a T^\t, posterior condylar fossa, containing usually the posterior condylar
foramen ; this gives passage to a vein, but it varies greatly in size, and is often

34

THE BONES OF THE HEAD.

absent on one or both sides. Externally to the condyle is a projecting portion of
bone known as the jugular process ; this lies over the transverse process of the atlas,
and is continuous behind with the tabular part, while in front it has a free excavated
margin, the jugular notch, which contributes, with a notch in the temporal bone, to
form the jugular foramen. Its extremity presents a small irregular surface, which
articulates with the jugular facet of the petrous part of the temporal bone by
synchondrosis, passing into osseous union at about twenty-five years of age. The
upper surface of the jugular process is marked by a deep groove for the lateral sinus

SUP. TEMP. LINE

INF. TEMP. LINE

Fig. 34. — Right parietal bone : external surface. (Drawn by D. Gunn.) f

leading to the jugular notch, and here is seen the inner opening of the posterior
condylar foramen ; the under surface is rough for the insertion of the rectus capitis
lateralis muscle.

The basilar process projects forwards and upwards in the middle of the base
of the skull. It increases in thickness and diminishes in breadth towards its
extremity. On the inferior surface in the mid-line is a small elevation, ^;7?ary7?^M/
tiibercle, for the attachment of the fibrous raphe of the pharynx, and on each side of
this are impressions for the rectus capitis anticus major and minor muscles. Its
superior surface presents a central smooth hollow, the basilar groove, which supports
the medulla oblongata, and close to each lateral margin a shallow groove for the
inferior petrosal sinus.

Varieties. — The portion of tlie bone above the superior curved lines, which represents the
interparietal bone of lower animals, is in rare cases separated from the rest by a suture
running transversely from one lateral angle to the other ; i^ai-tial separation by lateral fissures
is often met with (p. 73). The area between the superior and highest curved lines is
occasionally very prominent, constituting the torus occipitalis transi-crsus. In some bores
there is a groove along the internal occipital crest for the occipital sinus. The anterior
condylar foramen is not unfrequently double. An intrajvgular j^rocess is often seen in the
form of a small projection at the fore part of the jugular notch ; occasionally it is longer, and
meets the petrous portion of the temporal bone (p. 71). A projection from the under aspect

THE PARTETAL BONE.

35

of the jugular process represents the jyai-a mastoid pTorcfx of many mammals : it may be so lon^
as to meet the transverse process of the atlas. In rare cases an additional articulation is
formed between the basilar process and the anterior arch of the atlas, or the tip of the odontoid
process.

THE PARIETAL BONE.

The parietal bones form a considerable part of the roof of the skull. They
have the shape of quadrilateral plates, convex externally, concave internally. They
are a little broader and thicker above than below ; the anterior inferior angle is the

PACCHIONIAN
DEPRESSIONS

LONGITUDINAL

SULCUS

PARIETAL FORAMtM

LATERAL SULCUS

Fig. 35. — Right parietal bone : internal surface. (Drawn by D. Gunn.)

most projecting. They articulate with each other in the middle line above, with the
frontal bone anteriorly, the occipital posteriorly, and the temporal and sphenoid
below.

On the outer surface, near its middle, a more marked convexity exists, forming
tlie jKirieial eminence. Passing through or close below this are the superior
and inferior iemporcil lines, enclosing between them a narrow curved portion of
the surface, which is usually smo( thcr and more polished than the rest. Below^ the
inferior temporal line is the femporal surface, somewhat flattened, forming part of the
temporal fossa, and giving origin to the temporal muscle. The surface above the
upper line is covered only by the scalp. Close to the upper border, and nearer
to the posterior angle, is the small parietal foramen.

The inner surface is concave, the deepest part, opposite the parietal eminence,
being known a.s the par ietal fossa ; it is marked by shallow depressions corresponding
with the convolutions of the brain, and by narrower furrows, branching upwards and
backwards fi'om the lower border, for the meningeal vessels. The largest of these

36

THE BONES OF THE HEAD.

grooves, running from the anterior inferior angle, is sometimes converted into a
canal for a short distance. A slight depression along the inner part of the superior
border forms, with the one of the opposite side, the groove of the longitudmal smus •
and a depression at the posterior inferior angle forms a small part of the groove
of the lateral sinus. Near the upper border there are in most skulls, but particularly
in those of old persons, small irregular pits, lodging the Pacchionian bodies.

Borders.— "YlhQ anterior, superior, and posterior borders are deeply serrated. The
inferior border presents in the greater part of its extent a sharp or squamous edge,
with a slightly fluted surface" directed outwards, and overlapped at its anterior
extremity by the great wing of the sphenoid, and behind that by the squamous part

^ONT. Ervi.

TEMP. SUBF^

EMP. CREST

NG. PROC.

Fig. 36. — Frontal bone, from before. (Drawn by D. Gunn. ) f

of the temporal bone ; its posterior part is serrated, and articulates with the mastoid
portion of the temporal. The anterior border is slightly overlapped by the frontal
bone above, but overlaps the edge of that bone below.

Varieties. — The parietal foramen varies greatly ; frequently it is absent on one or botli
sides ; in extreme cases it has been seen more than half an inch in diameter. As a rare
occurrence the parietal bone is divided by a suture into an upper and a lower part. In senile
bones considerable depressions of the outer surface are sometimes met with, the floor of which
is not thicker than paper ; usually on both sides and symmetrical (Humphry, Med. Chir
Trans., 1890).

THE FRONTAL BONE.

The frontal "bone, arching upwards and backwards above the orbits, forms the
fore part of the cranium ; it likewise presents inferiorly two thin horizontal laminae,
the orlital plates, which form the roofs of the orbits, and are separated by a median
excavation, the ethmoidal notch. It articulates with twelve bones, viz., posteriorly
with the parietals and sphenoid ; outside the orbits with the malars j and between

THE FRONTAL BONE.

:i7

the orbits, from before backwards, with the nasal, superior maxillary, lachrymal, and
ethmoid bones.

Anterior surface. — The partformiu"; the greatest convexity of the forehead on
each side is called the frontal eminence. It is separated by a slight depression below
from the sumrciUarij ridge, a curved elevation of varying prominence above the

NASAL SPINE
/ NASAL SURFACE

NASAL NOTCH

TROCHLEAR FOSSA

FRONTAL SINUS

LACHRYMAL FOSSA

tlXT. ANG PROG.

ETHMOIDAL NOTCH

FiCr. 37. — Frontal bone, fro^ii below. (Drawn by D. Gimn.) |

.NASAL PROC.
OF MAX.

ANT. ETHM. CELL

margin of the orbit. Between the superciliary ridges is the surface called glabella.
The margin of the orbit, the orbital arch, is mosfc defined towards its outer part ; it
presents towards its inner third the supraorbital notch, sometimes a foramen, which
transmits the supraorbital nerve and artery. The extremities of the orbital
arch point downwards, and form the internal and
external angular processes : the internal is but slightly

•J i . NASAL BONE

marked ; it meets the lachrymal bone : the external is
strong and projecting, and articulates with the malar
bone. The temporal crest springs from the external
angular process, and arches upwards and backwards to
be continued into the temporal lines of the parietal
bone : it separates the temporal from the frontal part
of the outer surface of the bone.

Inferior surface. — The orbital surfaces are some-
what triangular, their internal margins being parallel,
while the external are directed backwards and inwards.
Close to the external angular process is the lachrgmal

fos.srt, which lodges the lachrymal gland; and close to the internal- angular pro-
cess is a small dei)ression, trochtear fossa, where the pulley of the superior
oblique muscle is attached. Between the orbits in front is the nasal notch,
bounded by a narrow semilunar serrated surface which articulates with the upper
ends of the nasal bones and the nasal processes of the superior maxillaj. Occu-
pying the concavity of the notch is the nasal process (Henle), which projects
beneath the nasal and maxillary bones, supporting the bridge of the nose. On
the posterior aspect of the nasal process are a small groov(xI surface on each
side, which enters into the formation of the roof of the nasal fossa, and a

Fig. 38. — Transverse section of

THE BRIDGE OK THE NOSE.

((i. D. T.)

38

THE BONES OF THE HEAD.

median ridge, which is continued into a sharp process of variable length, the nasal
spine. The latter descends in the septum of the nose, between the crest of the nasal
bones in front and the vertical plate of the ethmoid behind. Between the
ethmoidal notch and the inner margin of the orbital surface is an irregular area
occupied by depressions forming the roofs of cells in the ethmoid bone. Traversing
this surface are two grooves," which complete, with the ethmoid, the anterior
and posterior internal orbital canals ; the anterior transmits the nasal nerve and the
anterior ethmoidal vessels; the other, the posterior ethmoidal vessels. Farther
forward is the opening of the frontal sinus, a cavity which extends within the bone
for a variable distance behind the superciliary ridges. Outside and behind the

iLONGlTUDIMAi. SULCUS

^PACCHIONIAN DEPRESSIONS

MEMINQ.
GROOVES

NASAL SURFACE
NASAL SPINE

Fig. 39. — Frontal bone, fkom behind. (Drawn by D. Gunn.) |

orbital surface there is a large rough triangular area which articulates with the great
wing of the sphenoid.

Cerebral surface. — This surfa,ce forms a large concavity, except over the roofs
of the orbits, which are convex. Upon it are seen the impressions of the cerebral
convolutions, which, with the intervening ridges, are strongly marked over the orbits.
A groove, i\xQ frontal sulcus, lodging the superior longitudinal sinus, descends from the
middle of the upper margin of the bone, and is succeeded by the frontal crest, a ridge
which runs down nearly to the lower margin. A small foramen, usually formed in
part by the crista galli of the ethmoid, is situated at the base of the frontal crest ;
it is known as the foramen ccccuni, being generally closed below, but it may transmit
a minute vein from the nasal fossae. On each side small ramifying farrows, which
lodge branches of the middle meningeal vessels, run inwards from the lateral margin
of the bone ; and at the upper part, in the neighbourhood of the longitudinal groove,
are some depressions for Pacchionian bodies. The upper and greater part of
the edge encompassing the cerebral surface of the bone is serrated, and articulates

THE TEMPORAL BONE.

39

with the parietal boues in the coronal suture in the manner before described ; the
lower transverse part is thin and uneven, and articulates with the greater and lesser
wings of the sphenoid.

Varieties. — The trochlear fossa is often faintly marked or absent ; on the other hand
there may be a small prominence, thefror/ifrdr spine, by the side of the depression (10 percent.,
Merkel). The frontal bone is at times divided by a median frmttal or uu-tapic xuturc, the two
parts of the infantile bone havinu' failed to unite. This condition, which is termed metojjium,
was found by Anutschin to exist in 8-7 per cent, of European skulls, in 'rl per cent, in Mon-
golian races, in 1'2 per cent, of Xe^u'ro. and 1 per cent, of Australian skulls. A trace of the
metopic suture is to be seen in nearly all adult frontal bones above the root of the nose (fig. 36).

THE TEMPORAL BONE.

The temporal bone takes part in the formation of the side and base of the skull,
and contains in its interior the organ of hearing. It is usually described in three
parts, viz., an expanded anterior and superior part, the squamous portion, including

SQUAMOUS PORTION

MASTOID PORTION

STYLOID PROC.

Fig. 40. — Right temporal bone: uL'teu view. (Drawn by D. Gunn.)

the zygomatic process, a thicker posterior portion, the mastoid, and below and
between these the pcirous portion, a three-sided pyramid, exhibiting at its base
externally the aperture of the ear, and projecting forwards and inwards into the base
of the skull.

It articulates posteriorly and internally with the occipital bone, superiorly with
the parietal, anteriorly with the sphenoid, by the zygomatic process with the malar,
and by the glenoid cavity with the inferior maxillary bone.

The squamous portion, or squamo-zygomatic, extends forwards and upwards
from its conneoLion with the other portions, and is limited superiorly by an arched
border which describes about two-thirds of a circle.

40

THE BONES OF THE HEAD.

The inner surface is marked by cerebral impressions, and by meningeal grooves.
At its upper border the outer table is prolonged considerably beyond the mner,
forming a' thin scale with the fluted surface looking inwards and overlapping the
corresponding bevelled edge of the parietal bone. But in front, at its lower part,
the border is thicker, looks forwards and inwards, is bevelled slightly on the outer
side, and serrated for articulation with the great wing of the sphenoid.

The outer surface is in its greatest extent vertical, with a slight convexity, and

SQUAMOUS PORTION

SUP. PETR. SULCUS

LAT. SULCUS

MAST. FOR.

PETRO-SOUAM F S
TECMEN TYMPAW

CAR. CANAL

DEP. FOR CASS. CANGL.

INF. PETB. SULC

STYLOID PROC.

PETROUS PORTION

Fig. 41. — Right temporal bone: inker view. (Drawn by D. Gunn. )
The bone is rotated slightly about a sagittal axis, the upper border being moved inwards.

forms part of the temporal fossa. Above the aperture of the ear it is marked by a
small, nearly vertical furrow for the middle temporal artery. From the lowest
part of this surface a long process, the zygoma, takes origin.

The zygoma, or zygomatic process, is connected with the lower and outer part of
the squamous portion, and is of considerable breadth at its base, which projects
outwards. It then turns forwards, becomes narrower, and is twisted on itself so as
to present outer and inner surfaces and upper and lower borders. The superior
margin is thinner, and prolonged farther forwards than the inferior. The extremity
is serrated, and articulates with the malar bone. At its base the zygoma presents
two roots : the anterior, continuous with the lower border, is. a broad convex ridge,
directed inwards on the under aspect of the bone : the posterior, also called the
supramastoid crest, is prolonged from the upper border ; it passes backwards above
the external auditory meatus, marking the line of division between the squamous
and mastoid portions of the bone, and turning upwards posteriorly forms the
boundary of the temporal fossa. At the place where the two roots diverge is a
slight tubercle, which gives attachment to the external lateral ligament of the lower
iaw. Between the two roots is the glenoid fossa, a considerable hollow, elongated

THE TEMPORAL BOXE.

41

rEMP SuRF

PETROUS PORTION

AHTIC. EM

PETR. SULCUS

or COCHL.

from without inwards, and divided into two parts by the nearly transverse fisHure
of Glaser. The posterior part of the glenoid fossa is formed by the tympanic plate
of the petrous division of the bone, is non-articular, and lodges a portfon of the
parotid gland : the anterior part of the fossa, together with the cylindrical elevation,
articular eminence, formed by the anterior root of the zygoma in front of the hollow,
is coated with cartilage,

and forms the concavo- squamous portion

convex surface for arti-
culation with the lower
jaw ; the articular cavity
is bounded behind by
a small conical process
which descends in front
of the external auditory
meatus, and is known as
the posff/Icnoid process.
In front of the articular
eminence, and separated
from the temporal sur-
face by a skght ridge, is
a small triangular area
which enters into the
zygomatic fossa.

The mastoid por-
tion is rough externally
for the attachment of
muscles, and is prolonged
downwards behind the
aperture of the ear into
a nipple-shaped projec-
tion— the mastoid pro-
cess. This process has
on its inner side a deep
gr(iO\it,t\\ii(li(jasiricfossa,
which gives attachment

to the digastric muscle ; and internal to that is the slight occipital groove, for the
occipital artery. The internal surface of the mastoid portion is marked by a deep
.sigmoid depression, which is part of the groove of the lateral sinus. A passage
for a vein, of very variable size, the mastoid foramen, usually pierces the bone
near its posterior margin, and opens into the groove.

The petrous portion, so named from its hardness, contains the organ of
hearing. It forms a three-sided pyramid, Avith its base directed outwards, one
surface looking downwards, and the other two turned towards the interior of the
skull.

Inferior surface, base, and apex. — At the base is the aperture of the car. It
lorms a short canal, the external auditorij ineatus, directed inwards and a little
forwards, narrower in the middle than at its extremities, and leading into the cavity
of the tjjmpanum, part of which is seen from the exterior in the macerated bone.
The external orifice is bounded above by the posterior root of the zygoma, and in
the remainder of its circumferenf,-e chiefly by the external audituri/ process, a curved
uneven border, to which the cartilage of the ear is attached. This process is the
thickened outer extremity of the tijmjmnic plate, a lamina one surface of which
forms the anterior and inferior wall of the external auditory meatus and the

MAST. PROC

mastoid portion

Fig. 42. — Right temporal bonk, from below. (Drawn by D. Gunn.)

42 THE BONES OF THE HEAD.

tympanum, while the other looks towards the glenoid fossa. The upper margin of
the tympanic plate sinks beneath the squamous, and forms the posterior boundary
of the fissure of Glascr ; while its lower margin descends as a sharp edge, the
vaginal jjrocess, which partly surrounds the styloid process at its base. The styloid
process is long and tapering, and is directed downwards and forwards. It is placed
in front of the digastric fossa, and has immediately behind it the foramen which
forms the outlet of the canal of the facial nerve, named stylo-mastoid from its
position between the styloid and mastoid processes. Internal to the stylo-mastoid
foramen is a small irregular surface, the jugular facet, which articulates by syn-
chondrosis with the jugular process of the occipital bone. In fi-ont of this comes
a smooth and deep depression, the jugular fossa, which forms with the jugulai
notch of the occipital bone the jugular foramen. In front of the jugular fossa is
the carotid foramen, the inferior extremity of the carotid canal ; and internal to the
carotid foramen is a rough, free surface which is continued into the inner
extremity, or aioex of the petrous bone. The carotid canal ascends at first perpen-
dicularly, then turns horizontally forwards and inwards, and emerges at the apex,
close to the anterior margin ; it transmits the internal carotid artery.

The posterior surface looks backwards and inwards, and forms part of the
posterior fossa of the base of the skull. About the centre of this surface is a large
orifice leading into a short canal which is directed outwards, the internal auditory
meatus. This canal is terminated by a plate of bone named the lamina cribrosa,
from the numerous minute apertures which it presents for the divisions of the
auditory nerve, while in its upper and fore part is the beginning of the canal called
aqueduct of Fallopius, which transmits the facial nerve. The aqueduct takes a some-
what circuitous course through the petrous bone, passing outwards and backwards
over the labyrinth of the ear, and then downwards to terminate at the stylo-mastoid
foramen.

The anterior or upper surface looks upwards and forwards, and forms part of the
middle fossa of the base of the skull. A depression near the apex marks the
position of the Gasserian ganglion. A narrow groove runs obliquely backwards and
outwards to a foramen named the hiatus Fallopii, which leads to the aqueduct of
Fallopius, and transmits the large superficial petrosal nerve. Farther back is a
rounded eminence, indicating the situation of the superior semicircular canal.

The line of separation of this surface of the petrous from the internal surface of the
squamous is marked by a navvow 2^ctro-sq7/ am ous Jissurc, commencing anteriorly at the retiring
angle between the two portions, and generally to be traced less distinctly to the posterior
border of the bone. The portion of bone between this fissure externally and the eminence of the
superior semicircular canal and the hiatus Fallopii internally is a thin lamina, often perforated,
which roofs in the tympanum and the common canal of the Eustachian tube and tensor
tympani muscle, and is known as the tegmeit, tyvti^ani.

The superior lorder is grooved for the superior petrosal sinus. The anterior
'border is very short, and forms at its junction with the squamous part an angle in
which is situated the orifice of the Eustachian canal, the osseous portion of a tube
of the same name, which leads from the pharynx to the tympanum ; and above
this, partially separated from it by a thin lamella, the cochleariform process, is a
small passage which lodges the tensor tympani muscle. The piosterior or inferior
border internal to the jugular fossa articulates with the basilar process of the
occipital bone, and forms with that the groove for the inferior petrosal sinus.

Small foramina, &c. — The opening of the aqueduct of the vestibule is a narrow fissure,
covered oy a depressed scale of bone, and situated on the posterior surface of the petrous portion,
about four lines outside the internal auditory meatus ; that of the aqueduct of the cochlea is a
small foramen, beginning in a three-sided wider depression in the inferior margin, directly

CRISTA FALCIF.

THE SPHEXOID BONE. 43

below the internal auditory meatus. In the plate between the jugular fossa and the carotid
canal is the foramen by which the nerve of Jacobson passes to the tympanum. In the
ascendinyr part of the carotid canal is the minute foramen for the tympanic branch of the
carotid plexus. In the jug-ular fossa are a g'roove and foramen for the auricular branch of the
vagus nerve ; and parallel to the hiatus Fallopii. close to the canal for the tensor tympani
muscle, are a p'roove and foramen for the small superficial petrosal nerve.

The so-called fissure of Glaser is in the inner portion of its extent a double cleft, the
tympanic plate being- here separated from the squamous division of the bone by a descending^
process of the tegmen tympani, which forms the g-reater part of the outer wall of the common
canal of the tensor tymi^ani and Eustachian tube. Between this process and the tympanic
plate is a small orifice leading to the cavity of the tympanum, and lodging in the recen'o
state the slender process of the malleus and the tj'mpanic branch of the internal maxillary
artery : farther inwards is another small canal by which the chorda tympani nerve issues.
The outer portion of the Glaserian fissure is entirelj^ closed.

Tlie fundus of the internal auditory meatus may be aq. fall^ a^. crib. sup.

most conveniently studied in an infantile bone, where the
canal is short and the apertures relatively wide. A hori-
zontal ridge, named crisfa falcifd?-?}! is. rwas from the anterior
wall of tlie meatus across the lamina cribrosa. so as to sepa- ''°''- cent.coch-
rate a small superior from a large inferior fossa. At the
bottom of the superior fossa is a collection of minute aper- '""'^'- ^"'"^ ""*"•

tures giving passage to the filaments of the superior division of pjc, 43. Semi diagr.a.3im.\^tic

the auditory nerve, and constituting the rt/rrt c'/'(Z<;v».y«.s«^;f?7V);v,- view of the fundus of the

while the orifice of the aqueduct of Fallopius is placed on the right internal auditory

anterior wall of the fossa. In the inferior fossa are seen — meatus of an infant.

1, the a?-ea crlhrom mrdia. below the hinder part of the crest. (U. D. T.) \

for the nerve to the saccule; 2, the foranteti xinijuluri-. at

the lower and posterior part of the fossa, transmitting the nerve of the posterior semicircular
canal; and .8. the tmctiis sjtiralis forawinuJmttis, for the cochlear division of the auditory
nei-ve. a series of minute holes beginning below the area cribrosa media, forming one turn
and a half in a depression corresponding to the base of the cochlea, and ending at the foni men
ccJitrale cncltlnr. the orifice of the central canal of the modiolus.

From the fore part of the superior border of the petrous portion, where there is often a
small projection overhangiug the upper end of the groove for the inferior petrosal sinus
(fig. 69j, a fibrous band, the prtm-sphnuiidal ritjaitwat. extends to the lateral margin of the
dorsum sellas of the sphenoid bone. This completes a foramen through which the inferior
petrosal sinus and the sixth nerve pass. In rare cases the ligament is ossified.

The descrii)tion of the Small Bones of the Ear. with the Tympanum and Internal Ear, will
be found in the chapter on the Organs of the Senses in Vol. III.

THE SPHENOID BONE.

The sphenoid bone is placed across the base of the skull, uear its middle. It
enters into the formation of the cavity of the cranium, the orbits, and the nasal fossae.
It is of very irregular shape, and consists of a central part or hodij, a pair of lateral
expansions called the (jrcat wings, a pair of smaller horizontal processes above, called
the small icings, and a pair which project downwards, t\\Q j)tcrggoiil processes.

The sphenoid is articulated with all the seven other bones of the cranium and
with five of those of the face, viz., posteriorly Avith the occipita,! and with the
petrous portions of the temporals, anteriorly with the ethmoid, palate, frontal, and
malars, laterally with the squamous portions of the temporals, the parietals, and
frontal, and interiorly with the vomer and palate bones ; sometimes it touches also
the superior maxilla.

The body is hollowed out into two large cavities, the sphenoidal sinuses,
separated by a thin median lamina, the sphenoidal seplinn, and opening anteriorly
into the nasal fossie by two rounded apertures. The superior surface presents in
the middle a dee[) pit, the pituHarg fossa or sella turcica, which lodges the
pituitary ))ody. In front of the fossa is an elevated portion of bone on a level
with the optic foramina, the olivary eminence, on which the optic commissure rests
in the slight o/itic groove ; and in front of this is a surface on a somewhat higher level,
continuous with the superior surfaces of the small wings, and having a slight pro-

44

THE BONES OF THE HEAD.

jection forwards of its anterior border, which articulates with the cribriform plate
of the ethmoid, and is called the ethmoidal sjnne. Behind the pituitary fossa is a
prominent lamella, the clorswn sella, the posterior surface of which is sloped
apwards and forwards in continuation of the basilar groove of the occipital bone.
The angles of this lamella project over the fossa, and are called the posterior dinoid
^processes. On each side of the body the surface descends obliquely to a considerably
lower level than the fossa : it presents close to the margin of the fossa a superficial
winding groove directed from behind forwards, marking the course of the internal
carotid artery. Behind the commencement of the groove, and at the lower end of
the lateral margin of the dorsum sellse is a compressed projection, the petrosal

BODY SMALL WING GREAT WING

FOT ROTUNDUM
POST CLIN. PROC.
FOR OVALE
FOR. SPINOSUM

Fig. 44. — The sphenoid bone, from above. (Drawn by D. Gunn.)

process of the splienoid, which fits against the apex of the petrous jjart of the
temporal bone ; and opposite to this, on the outer side of the groove, the more
slender tongue-like process termed KnguJa sphenoidalis projects backwards in the
angle between the body and great wing.

The posterior surface is united to the basilar process of the occipital bone, in
early life by cartilage, but in adult age by continuous bony substance.

The anterior surface is marked in the middle line by. the sphenoidal crest, a thin
projecting edge which descends from the ethmoidal spine, and articulates with the
vertical plate of the ethmoid. The oblong surface on each side of the crest is
divided into a mesial and a lateral part : the lateral part is irregularly excavated,
and articulates with the lateral mass of the ethmoid and the orbital process of the
palate bone : the mesial part is smooth and free, entering into the formation of the
roof of the nasal fossa, and presenting near its upper end the rounded orifice of the
sphenoidal sinus. The sphenoidal crest terminates below in the rostrum, a sharp
vertical prominence which is continued back some distance on the inferior surface,
and fits in between the alse of the vomer. These last and the vaginal processes of
the internal pterygoid plates cover the great part of the inferior surface of the body.

The sphenoidal turbinate or spongy bones {conma sphenoidalia, hones of Bertin) form a
considerable part of the anterior wall of the body of the sphenoid, bounding the foramen of
each sinus. These bones have a triangular form, with the apex directed downwards and back-
wards, and are in the adult usually incorporated with the sphenoid, but as explained in the

THE SPHENOID BOXE.

45

account of their development, were orig-inallj' distinct. They are commonly united by earlier or
stronger anchylosis with the ethmoid or palate bones, so as to come away, at least in part, with
either of these in disarticulation of the skull, and thus lay open the sphenoidal sinuses. A small
portion of these bones sometimes appears on the inner wall of tlie orbit, between the ethmoid,
frontal, sphenoid, and palate bones (Cleland in Phil. Trans.. 1802).

Each Jateral surface of the body is for the most part occupied by the attachments
of the two wings, but at the fore part, below the root of the small wing, there is ?
small free surface which bounds the sphenoidal fissure internally and forms the hind-
most portion of the inner wall of the orbit (fig. G'J, p. 6(5).

The small or orbital wings extend nearly horizontally outwards on a level with

GREAT WING

PTERYGOID PROCESS

Fig. 45. — The sphenoid bone, from behind. (Drawn by D. Gunii. )

the fore part of the superior surface of the body. The extremity of each is slender
and pointed, and comes very close to, but usually not into actual contact with, the
great wing. The superior surface forms part of the anterior fossa of the base of the
cranium ; the inferior overhangs the sphenoidal fissure and the back of the orbit.
The anterior border, thin and serrated, articulates with the orbital plate of the
frontal bone. The posterior border is prominent and free, and forms the boundary
l>etween the anterior and middle cranial fossae, terminating internally in a smooth
rounded projection, the anterior clinoid process. Between the anterior clinoid pro-
cess and the olivary eminence is a semicircular notch in which the carotid groove
terminates ; and in front of this is the optic foramen perforating the base of the
wing.

The great or temporal wings project outwards and upwards from the sides of
the body. The back part of each is placed horizontally, and occupies the angle
between the petrous and squamous portions of the temporal bone ; from its pointed
extremity it sends downwards a short and sharp projection, the spinous 2^rocess.
The upper and fore part is vertical, and three-sided, lying between the cranial
cavity the orbit, and the temporal f(jssa (fig. GG, p. G4). The cerebral, surface of the

46

THE BONES OF THE HEAI).

o-reat wing is concave, and forms part of the middle fossa of the nase of the cranium.
The external surface (temporo-zygomatic) is divided by a rid^, infratemporal crest,
into an inferior part, which looks downwards into the zygomatic fossa, and an elongated
superior part; looking outwards, which forms a part of the temporal fossa (fig. 68,
p. G6). The anterior surface looks forwards and inwards, and consists of a quadri-
lateral orUlal portion, which forms the back part of the external wall of the orbit, and
Df a smaller inferior portion which overhangs the pterygoid process, looks into the
spheno-maxillary fossa, and is perforated by the foramen rotundum. The posterior
larder in its mesial part bounds the foramen lacerum, in its lateral part articulates

GREAT WING

SMALL WING

NFRRTtMP.
CREST

ZYCOM. SURF.

SPHENO-MAX. SURF.

EXT. PTERYC. PLATE

PTERYC. NOTCH

HAMULAR PROC.

PTERYGOID PROCESS

Fig. 46. — The sphenoid bone, from before. (Drawu by D. Gnnn.)

with the petrous, and forms with that a groove on the under aspect for the carti-
laginous part of the Eustachian tube. The external margin articulates with the
squamous, and the extremity overlaps the anterior inferior angle of the parietal. In
front of this comes a triangular surface, the sides of which are formed by the upper
margins of the cerebral, orbital, and temporal sui'faces respectively, for articulation
with the frontal bone. The anterior margin, between the orbital and temporal
surfaces, articulates with the malar bone ; and below this is a short horizontal free
edge separating the zygomatic and spheno-maxillary surfaces. Above and internally
the orbital and cerebral surfaces meet at the sharp border w^hich forms the inferior
boundary of the sphenoidal fissure, and which is frequently marked at its inner part
by a small projection giving attachment to the lower head of the external rectus
muscle of the eyeball.

The pterygoid processes project downwards and slightly forwards from the
adjacent parts of the body and the great wdngs. Each consists of two plates united
in front and diverging behind, so as to enclose between them the pterygoid fossa, in
which the internal pterygoid muscle arises. The external pterygoid plate, broader
than the internal, lies in a plane extending backw^ards and outwards ; its outer
surface bounds the zygomatic fossa, and is impressed by the external pterygoid

THE ETHMOID BONE. 47

muscle. The iniernal j)terijgoid jylate is longer and narrower than the external, and
is prolonged below into the slender hook-like or hamular process, round which in a
groove plays the tendon of the tensor palati muscle. Above, the internal plate turns
inwards beneath the body, from which its extremity remains distinct as a slightly
raised edge, known as the varjinal process, which articulates with the everted margin
of the vomer ; externally to this it is marked by a small groove, which contributes
with the palate bone to form the ptcrygo-jmlatine canal. Posteriorly, the internal
pterygoid plate forms at its base a small blunfc prominence, the jyterijfj aid tubercle, to
the inner side of and below the orifice of the Vidian canal ; between this and the
pterygoid fossa is a slight depression, called the navicickcr or scaphoid fossa, occupied
by the attachment of the tensor palati muscle ; and lower down, on the hinder
margin of the plate, is a projection which supports the cartilage of the Eustachian
tube. The interval between the lower ends of the pterygoid plates, pteryyoid notch,
is occupied by the pyramidal process of the palate bone.

Fissures and foramina. — Each lateral half of the bone presents a fissure, four
foramina, and a canal. The sphenoidal fissiire is the obliquely placed elongated
interval between the great and small wings, closed externally by the frontal bone ;
it opens into the orbit, and transmits the third, fourth, and sixth nerves, the
ophthalmic division of the fifth nerve, and the ophthalmic veins. Above and to the
inside of the sphenoidal fissure is the optic foramen, which is inclined outwards and
forwards from the side of the olivary eminence, pierces the base of the small wing,
and transmits the optic nerve and the ophthalmic artery. The forameti rot mid urn is
directed forwards through the great wing, below the sphenoidal fissure ; it opens
immediately below the level of the orbit, and transmits the superior maxillary nerve.
The foramen ovale is large, and placed behind and a little external to the foramen
rotundum, near the posterior margin of the great wing ; it is directed downwards,
and transmits the inferior maxillary nerve and small meningeal artery. The
foramen spinosiim is a small foramen piercing the great wing, near its posterior
angle, and transmits the large middle meningeal vessels.

The Vidian or pteryyoid canal pierces the bone in the sagittal direction at the
base of the internal pterygoid plate. It opens anteriorly into the spheno-maxillary
fossa, and posteriorly into the foramen lacerum ; and through it pass the Vidian
nerve and vessels.

Varieties.— A small tubercle is often seen on each side in front of the pituitary fossa, at
the base of the olivaiy eminence, and immediately internal to the last part of the carotid
groove ; this is knowm as the middle clinnid procct-t, and is sometimes connected by a spiculum
of bone to the anterior clinoid process, forming a carotico-clinoid foramen. Less frequently
the anterior and posterior clinoid processes are similarly united. There are normally fibrous
bands, inter clinoid lifiavicntx, beneath the dura mater in these situations (Gruber). In some
cases a mperior j>etrosal procen projects from the lateral margin of the dorsum sella; (fig. 6Lt),
giving attachment to the petro-sphenoidal ligament (p. 4.3). The outer pterygoid plate may
be connected Vjy a bridge of bone or of ligament {ptcrygo-spiiiou.<i) with the spinous process.
The foramen ovale and foramen spinosum are frequently incomplete at the posterior margin
of the bone. The name of foramen of Vcsalma is given to an aperture sometimes present on
the inner side of the foramen ovale : it gives passage to an emissary vein. At the base of the
spinous process, to the inner side of the foramen spinosum, there is occasionally a minute canal
(canaliculus innominatus — .tVi-nold) transmitting the small superficial petrosal nerve.

THE ETHMOID BONE.

The ethmoid, or sieve-like bone, projects downwards from between the orbital
plates of the frontal bone, and enters into the formation of the cranium, the orbits,
and the nasal fossae. It is of a cuboid figure, and exceedingly light for its size,
being composed of very thin plates of bone surrounding in gi-eat part irregular cells

48

THE BONES OF THE HEAD.

STA CALL!

ALAR PROCESS

UNCINATE PROCESS

It consists of a central vertical plate, and of two lateral masses, united at their
superior borders by the liorizontal cribriform plate. It articulates with thirteen
bones : the frontal, sphenoid and vomer, the nasal, lachrymal, superior maxillary,
palate, and inferior turbinate bones.

The vertical plate lies in the median plane, and forms the upper third of the
septum of the nose (fig. 71, p. 69). Its superior border appears in the cranial
cavity, above the cribriform plate, in the form of a ridge, rising anteriorly into a
thick process, the crista galli, to which the falx cerebri is attached. The posterior
margin of the crista galli is thin and smooth. The anterior is in its lower part
broadened out, and divided into two alar jwocesses, which project laterally, and are
rough in front for articulation with the frontal bone : between them there is usually
a median groove completing the foramen cacmn. Below the level of the

cribriform plate, the anterior
border of the vertical plate
slopes much forwards, and
articulates with the nasal spine
of the frontal and with the
nasal bones. The inferior
margin articulatesin front, and
sometimes even in its whole
extent, with the septal carti-
lage of the nose : in its pos-
terior half, in the adult, it is
more or less completely joined
by osseous union on one or
both sides to the two plates
of the vomer. The posterior
margin is very thin, and is
united to the crest of the
sphenoid. This plate presents superiorly a number of grooves and minute canals,
leading from the foramina of the cribriform plate, for the transmission of the
olfactory nerves.

Each lateral mass or labyrinth encloses a number of spaces of irregular
form, arranged in three sets, the anterior, middle, and jjosterior ethmoidal ce//s, which
in the recent state are lined with prolongations of the mucous membrane of the
nose. On its external aspect is a thin, smooth lamina, of an oblong form, the
orbital plate or os planum, which closes in the middle and posterior ethmoidal cells,
and forms a considerable part of the inner wall of the orbit (fig. 69, p. 66). The
circumference of the orbital plate articidates in front with the lachrymal, behind with
the sphenoid, above with the frontal, and below with the superior maxillary and palate
bones, which often complete two or three ethmoidal cells. At the lower part of this
aspect is a deep groove, which belongs to the middle meatus of the nose, and is
limited below by the rolled margin of the inferior turbinate jjrocess. Anteriorly, the
groove curves upwards, and is continued into a passage named the infundibiduni-
which leads through the fore part of the lateral mass into the frontal sinus. Into
the horizontal part of the groove the middle ethmoidal cells open, and into the
ascending part the anterior ethmoidal cells. In front of the orbital plate, the
lateral mass extends forwards under cover of the lachrymal bone, which closes over
the open anterior ceUs seen in the disarticulated ethmoid bone ; and from this part
descends the uncinate process, a long thin lamina, which curves backwards, down-
wards and outwards in the groove of the middle meatus. In the complete skull the
uncinate process lies across the orifice of the antrum of the superior maxilla, and
forms part of the inner wall of that cavity ; at its extremity it articulates, by means

Fig. 47.

-The ethmoid bone, from the right side.
(Drawn by D. Gunn.)

THE ETHMOID BONE.

Ad

of one or two irrecrular projections, with the ethmoidal process of the inferior tur-
binate ))one (fig. (iO, p. 6G).

Tlie iniernal aspect of each lateral mass forms part of the external wall of the
nasal fossa, and consists of a thin, uneven lamella, connected above with the cribri-
form plate, and exhibiting a number of canals and grooves for branches of the
olfactory nerve. It is divided at its back part by a cliannel, directed forwards from
its posterior margin to about its middle. This is the superior moatvs of the nose,
and communicates witii the posterior ethmoidal cells.
overhangs this channel, is'tlie superior tur-
Mnate process or spongy hone. Below the
groove is another plate, somewhat thick-
ened and rolled outwards inferiorly, the
inferior turbinate process or middle spongy
hone. This is free also in front and

The short, thin plate which

STA CALL!

SUP. TURS. GONE
IP. MEATUS

MIO. TURB. BONE

Fig. 48. RiOHT LATERAL MASS OF ETHMOID BOXE ;

ix>"ER SURFACE. (Drawn by D. Gunn.)

Fig. 49.— The ethmoid bone, from above.
(Drawn by D. Gunn.)

behind, and, as has already been seen on the outer aspect, overhangs the middle
meatus of the nose.

The superior margin of the lateral mass is covered, and the cells completed, by
the projecting inner border of the orbital plate of the frontal bone ; two grooves are
seen crossing it, which complete with the frontal bone the internal orbital canals.
The inferior margin is formed by the rounded edge of the middle turbinate bone,
and is free in the nasal fossa.- The anterior extremity presents one or two open
cells, which are closed by the nasal process of the superior maxilla ; and the posterior
extremity fits against the front of the body of the sphenoid, where it is commonly
anchvlosed with the sphenoidal spongy bone.

The cribriform plate corresponds in size to the ethmoidal notch of the frontal
bone, which it occupies. On each side of the crista galli it is depressed into the
olfactory groove which lodges the olfactory bulb, and is pierced by numerous
foramina for transmission of the filaments of the olfactory nerves. The foramina
in the middle of the groove are few, and simple perforations ; the internal and
external sets, more numerous, ai-e the orifices of small canals which subdivide as
they descend on the vertical plate and lateral mass. At the anterior extremity is a
Bmall fissure on each side of the crista; galli, close to its base ; and externally to this
is a notch or foramen, connected by a gi'oove with the anterior internal orbital
canal, which truDsmits the nasal branch of the ophthalmic nerve.

5C

THE BONES OF THE HEAD

THE SUPERIOR MAXILLABY BONE.

The upper jaw, superior maxilla, is the principal bone of the face ; it supports
all the teeth of the upper range, and takes part in the formation of the hard palate,
the floor of the orbit, and the floor and lateral wall of the nasal cavity. It consists
of a central part or bodij, and four processes. The body presents an external
surface, which is again subdivided into anterior or facial, and posterior or zygomatic
portions ; an internal or nasal surface, and a superior or ordifal surface. The pro-
cesses are — the 77asal or ascending, projecting upwards from the fore part of the
body, the alveolar, forming the lower border of the bone and containing the alveoli
or sockets for the teeth, the malar on the outer aspect, separating the facial and

INFBAORB. CROOVE

MALAR PRO

TUBEROSIT

Fig. 50. —Right superior maxillary boke : outer view. (Drawn by D. Gxinn.)

zygomatic surfaces, and the palate process, j)rojecting horizontally on the inner side.
The body is farther excavated by a large sinus or antrum, which opens on the inner
side into the nasal fossa. The superior maxillary bone articulates with its fellow,
with the nasal, frontal, lachrymal, ethmoid, palate, malar, vomer, and inferior tur-
binate bones, and sometimes with the sphenoid.

The facial surface is marked at the lower part, where it is continuous with the
outer surface of the alveolar process, by a series of eminences corresponding in.
position to the fangs of the teeth ; that of the canine is particularly prominent, and
internal to this is a slight depression, the incisor or 7n7jrtiform fossa ,- while between
it and the malar process is the deeper canine fossa. Above the canine fossa, and
close below the margin of the orbit, is the infraorhital foramen, by which the infra-
orbital nerve and artery issue. The inner margin of this surface is deeply excavated
by the nasal notch, the sharp edge of which is produced below into the anterior
nasal sjyine.

The zggomatic surface looks into the zygomatic and spheno-maxillary fossae ; it is
convex, and presents about the centre one, two or more apertures of the posterior
dental canals, transmitting the vessels and nerves of that name ; the lower and
posterior part of this surface is prominent and rough, and is distinguished as the
tuberosity.

THE SUPERIOR MAXILLARY BONE. 51

The jiasal surface presents at the fore part a nearly horizontal ridge, the inferior
turhimite crest, for articulation with the inferior turbinate bone : below the crest is
a smooth concave surface belonging to the inferior meatus of the nose ; and above
the crest a smaller surface, extending on to the base of the nasal process, and bound-
ing the atrium of the middle meatus. Behind the nasal process is seen the
Vichrijmal groove, nearly vertical, but inclined slightly ijackwards and outwards, about
half an inch in length, and leading into the inferior meatus ; the margins overhang
the groove in front and behind, and the small interval left is closed by the lachrymal
and inferior turbinate boues, thus completing the canal of the nasal duct. Behind
the lachrymal groove is the large opening into the antrum ; and above this there are

POST. PAL. GROOVE

PALATINE Pnoc.

EOLAR PBOC.

Fig. 51. — Rii;iiT srPERTOR m.willary bone: inner view. (Drawn by D. Gunn. )

often one or two small hollows which complete the middle ethmoidal cells. Behind
the opening of the antrum the surface is rough for articulation with the palate bone ;
and traversing the lower part of this roughness is a smooth groove, directed down-
wards and forwards from the posterior margin, and completing with the palate bone
the jmsterior palatine or paJafo-marillari/ canal.

The orbital svrfore is triangular, flat, and smooth ; anteriorly it reaches the
margin of the orbit for a short distance at the root of the nasal process : externalh
it is bounded by the rough surface for the malar bone. The internal border presents
behind the nasal process, an excavation which receives the lachrymal bone, the
ImJiri/raal notch, and then a nearly straight margin for articulation with the
ethmoid and palate bones. The ])Osterior border is smooth, rounded and free, and
bound.s the spheno-maxillary fissure ; the infraorhital (jroove commences here, and
leads forwards into the canal of the same name, which opens anteriorly by the infra-
orbital foramen. From the infraorbital are given off the anterior and middle dental
tanals, which run down in the substance of the facial portion of the bone, and
convey the anterior and middle dental vessels and nerves.

The nasal process, slender and tapering, has an external surface, smooth and
continuous with the facial surface of the body, and an internal surface, the hinder

E 2

r;2 THE BONES OF THE HEAD.

part of which is irregular, and fits against the anterior extremity of the lateral mass
of the ethmoid, comjjleting the foremost cells of that bone ; in front of this the
surface is free in the outer wall of the nasal fossa, and in its lower part is crossed by
•a smooth oblique ridge, called the agger nasi, which forms the upper boundary of
(he atrial surface of the body. The anterior border is rough, often grooved, for
articulation with the nasal bone, and its summit is serrated for articulation with the
frontal. Posteriorly, it presents a continuation of the lachrymal groove, which has
already been seen oii the nasal surface of the body, and which here lodges the lachry-
mal sac : the groove is bounded internally by a sharp linear edge, which articulates-
with the lachrymal bone, and externally by a smooth border which forms part of the
orbital margin.

The alveolar Urcler or process, thick and arched, is hollowed out into sockets
or alveoli, corresponding in number, form, and depth to the roots of the teeth, which
are fixed in them.

The malar process is thick and triangular: its anterior and posterior surfaces
are continuous with the facial and zygomatic surfaces of the body ; the superior is

Fig. 52. — Front part of the palate and alveolar arch of an

ADULT. I

Showing the openings into the anterior palatine fossa. 1, 2, are
placed on the palate plates of the superior maxillary bones ; 4, anterior
palatine fossa, in which are seen four openings— the two lateral, with
lines pointing to them from 1 and 2, are the incisor foramina ; the
anterior and posterior, indicated by 3 and 4, are the foramina of
Scarpa.

rouo-h and grooved to support the malar bone. The inferior border runs down on
the*outer surface of the body in the form of a thick buttress opposite the first molar

tooth.

The palate process or jjlate, along with that of the opposite side, forms about three-
fourths of the hard palate. Its superior surface is smooth, and concave from side to
side ; its inferior surface is vaulted and rough, and is marked laterally with grooves
for nerves and vessels, which reach the palate through the posterior palatine canal.
Its posterior extremity falls short of that of the alveolar arch and body of the bone,
and articulates with the horizontal plate of the palate bone, which completes the-
hard palate. The mesial border, finely serrated, rises into a vertical ridge, which, with
its fellow, constitutes the nasal crest— Si grooved elevation receiving the lower margin
of the vomer ; at the fore part this border rises suddenly to a considerable height,
and the more elevated portion is distinguished as the incisor crest ; forwards this is
prolonged into the anterior nasal spine, on its upper border rests the septal cartilage
of the nose, and into the angle behind it the truncated anterior extremity of the
vomer fits. Close by the side of the incisor crest on the upper surface of the palate
plate is seen a foramen which is directed downwards to the mouth, but in the lower
half becomes converted into a wider groove by deficiency of the inner wall. Thus,
when the two bones are placed in apposition, one orifice of considerable size is
formed on the palatal aspect, which divides above into right and left branches leading
to the corresponding nasal fosste ; the lower aperture is the anterim' palatine fossa (or
canal), the lateral branches are the incisor foramina (or canals) or foramina of
Stensen. Farther, in the middle line are two other smaller foramina opening into
the anterior palatine fossa, one before, the other behind ; these are the foramina of
Scarpa.

The incisor foramina are placed between the two elements, the premaxilla and the maxilla
proper, which make up the superior maxillary bone of human anatomy, and are the remains
of a primitive communication between the nose and mouth. In the lower animals they are-

THE PALATE BONE.

53

generallv of larire size, and open separately on the palate. A median anterior palatine fossa
receiving the two incisor foramina is met with only in man and a few animals, and the deeply
placed lamina which then bounds the incisor foramen on the inner side corresijonds to the
mesial palatine process of the premaxillary bone of other animals. The foramina of Scarpa
lie in the suture between the laminae referred to. They transmit the naso-palatine nerves, tlie
nerve of the right side occupying, according to Scarpa, the posterior one. which is usually tlie
lai-ger. and that of the left side, the anterior ; but they are very nicoufctant. (Scarpa, Annot.
Anatom.. lib. ii, cap. .').)

The maxillary sinus or anirum of Highmore has an irregularly pyramidal form.
Its \valls are thiu : the sides correspond to the facial, zygomatic and orbital surfaces
of the body ; the base to the nasal surface ; and the apex extends into the malar
process. The large aperture is closed to a considerable extent by the uncinate
process of the ethmoid, the palate and inferior turbinate bones ; and in the fresh
state it is reduced by the mucous membrane to a small orifice through which the
cavity communicates with the middle meatus of the nose. Its extent below generally
corresponds with that of the molar teeth, and the outer alveoli of one or more of
these form prominences in its floor.

THE PALATE BONE.

The palate bone forms the back part of the hard palate and the lateral wall
of the nose between the superior maxillary bone and the internal pterygoid plate.
It consists of a horizontal and a vertical plate united at a right anole, and of
three processes, viz., the tuherositij or
pyramidal process, extending outwards
and backwards from the junction of
the horizontal and vertical plates, and
the orbital and spltenoidal processes,
surmounting the vertical plate.

The palate bone articulates with its
fellow, and with the superior maxillary,
ethmoid, sphenoid, vomer, and inferior
turbinate bones.

The liorizontal or jmlafe plate pre-
sents a superior surface, concave and
smooth, forming the back part of the
floor of the nasal fossa, and an inferior
surface, completing the vault of the hard
palate, and marked near its posterior
border by a transverse ridge to which
some tendinous fibres of the tensor
palati muscle are attached. The anterior border articulates with the palate process
of the superior maxilla ; the posterior is free, concave and sharp, giving attach-
ment to the soft palate, and produced at its inner end into a sharp point, which
with that of the other side forms the posterior nasal or palatine spi7}e ; internally
it articulates with its fellow by a thick sen-ated border, forming a continuation of
the nasal crest of the superior maxillae, and also supporting the vomer ; externally, at
its junction with the vertical plate, it is grooved by the extremity of the posterior
palatine canal.

The vertical plate is very thin. Its internal or nasal surface is divided into two
parts, corresponding to the middle and inferior meatuses of the nose, by a nearly hori-
zontal ridge, the inferior turlinate crest, which articulates with the inferior turbinate

"'-

iC

ITAL

PROCESS

SPHENOID,^

^^W<

.ORBIT

SPHENOIDAL \

^

fhr^

PROCESS Ig

1

itl'^u

•SPHE:N. max. FOSSA

PTER. PAL. CAN.

SPHEN. PAL. notch'

/

k'^ VERTICAL PLATE

INF.TURB. CREST-

-

-4

km

,

NASAL CREST

V

li

\/n::r

'OST. NASAL i\

km

^%

^-"^^-^^

E

d

Wk

^^ EXTPTE,

HORIZONTAL

PLATE Nf»

L*^^^^

/

53.

-Right i'.\i>.\te bone, from behind.
(Drawn by D. Gumi.)

54.

THE BONES OF THE HEAD.

bone ; and at the npper end of the surface, crossing the roots of the two processes,
is another less marked ridge, the ethmoidal or superior turlinate crest, which articu-
lates with the middle turbinate bone. The external surface presents, nearer to the
posterior border, a narrow smooth surface which forms the inner Avail of the pterygo-
maxillarj fissure, and leads down to a deep groove forming with the superior maxil-
lary bone the palato-maxillary or posterior palatine canal for the transmission of
the large palatine nerve and vessels ; in front of the groove the surface is applied
against the superior maxillary bone, and overlaps the orifice of the antrum by a thin
tongue-shaped projection, the maxillarij frocess, which may attain a considerable
size ; behind the groove it articulates inferiorly with the hinder border of the
maxilla, superiorly with the inner surface of the pterygoid process.

Fig. 54. — Right palate bone: A, outer view; B, inner A'iew. (Drawn by D. Gimn.)

The pyramidal process or tuberosity fits into the notch between the pterygoid
plates. It presents posteriorly a triangular surface Avhich is concave and smooth,
and completes the pterygoid fossa : on each side of this is a narrow areaj the
internal deeply grooved, the external rough, for articulation with the anterior
border of the corresponding pterygoid plate. Externally there is a small free
surface which appears between the tuberosity of the superior maxillary bone and the
pterygoid process in the zygomatic fossa (fir. 68). Inferiorly, close to its con-
nection with the horizontal plate, are the orifices of the piosterior and external
accessory palatine canals which transmit the lesser palatine nerves ; the external is
the smaller and less constant.

The orhital process surmounts the anterior margin of the vertical plate. It is
somewhat pyramidal in shape, and has five surfaces, two of which, the superior and
external, are free, and the rest articulated. The superior surface forms the posterior
angle of the floor of the orbit (fig. 69), the external looks into the spheno-
maxillary fossa, the anterior articulates with the maxillary, the internal with the
ethmoid, and the posterior, which is small, articulates with the sphenoid. The
process is generally hollow, and the cavity completes one of the posterior ethmoidal
ceUs, or it may open behind into the sphenoidal sinus.

The sphenoidal process curves upwards and inwards from the posterior part
of the vertical plate. Its superior surface is in contact Avith the body of the
sphenoid and the base of the internal pterygoid plate, and is grooved for the com-
pletion of the pterygo-palatine canal ; its internal or under surface looks to the

THE VOMER.

55

nasal fossa : and at its base a third surface looks forwards and outwards into the
spheno-maxillary fossa. Its inner extremity touches the ala of the vomer.

The two processes are separated by the deep spheno-palatine notch, which is
closed above by the body of the sphenoid, and thus converted into the foramen of
the same name. It leads from the spheno-maxillary fossa into the nasal cavity, and
transmits the internal nerves from 3Ieckel's ganglion and the nasal branch of the
internal maxillary artery, with corresponding veins.

Varieties. — The groove of the posterior palatine canal is sometimes closed in below, so
that the opening on the palate is bounded solely by the palate bone. The spheno-palatine
notch may also be converted into a foramen by the union of the upper ends of the sphenoidal
and orbital processes : or the foramen may be double from the development of an intermediate
osseous bridge. The orbital j^rocess varies greatly in size ; its orbital surface is freauently
enlarged from the union with the palate bone of a portion of bone ossifying from a se^mrate
centre, usually united with the ethmoid or sphenoid, and already described with the sphe-
noidal spongy bone (_p. 45). The external accessory jialatine canal is often wanting ; or it
may be placed between the jDalate and superior maxillary bones.

THE VOMER.

The vomer is a thin median bone, irregularly ([uadrilateral, and placed
vertically between the nasal fossa3. It articulates with the sphenoid, ethmoid,
palate, and superior maxillary bones, and with the septal cartilage of the nose.

The surfaces are smooth and in
the recent state covered by mucous
membrane ; each is traversed by a
faint groove running downwards
and forwards, and conducting the
naso-palatine nerve to the canal of
Scarpa. The superior border is by
far the thickest part of the bone,
and is divided into two spreading
akd, which fit under the body of the
sphenoid, receiving the rostrum into
the groove between them ; the edge
of each ala meets the vaginal process
of the sphenoid and the cphenoidal
process of the palate bone. The anterior border, sloping downwards and forwards,
is grooved for the septal cartilage, and in the upper half is united by anchylosis on
one or both sides with the perpendicular plate of the ethmoid.

The anterior extremity of the vomer forms a short vertical edge which fits in
behind the incisor crest of the maxillaries, and from the upper end of which a process
projects forwards in the groove of the crest, while from its lower end a point
sometimes projects downwards between the incisor foramina. The inferior border
articulates with the nasal crest of the maxillary and palate bones. The posterior
border, thin, smooth, and unattached, separates the posterior nares.

GROOVE OF NASO-

Fig

55. —Vomer, from the right side.
(Drawn by D. Griinn. )

THE MALAR BONE.

The malar bone forms the most prominent part of the cheek, and separates
the orbit from the tempoi'al fossa. It is quadrangular in shape, with the angles
directed vertically and horizontally. The outer surface is convex, and presents a
little below the centre a slight elevation called the malar tuherosity ; above this is
the orifice of the malar canal. The inner surface is concave, and looks into the

56

THE BONES OF THE HEAD.

temporal nnd zygomatic fossEe. The upper angle, frontal process, is the most
prominent, and is serrated at the extremity for articulation with the external angular
process of the frontal bone. The border behind this, temporal, is sinuous and con-
tinuous with the upper edge of the zygoma. The posterior angle, temporal process, is
serrated for articulation with the extremity of the zygoma, and the postero-inferior
border, masseteric, thick and rough, completes the lower edge of the zygomatic arch.
The antero-inferior border, maxillary, together with a rough triangular part of the
inner surface, articulates with the mala.r process of the superior maxilla. The
remaining border, orbital, is strongly excavated, smooth and rounded, and forms a
great part of the orbital margin ; from this the orbital process projects backwards

FRONTAL- PROe.

TAL PROC.

TEMP-ZYCOM. SU

TUBEROSITY

Fig. 56. — Right malar bone : outer view.
(Drawn by D. Gunn.)

Fig.

. — Right malar bone : inner a'IEW.
(Drawn by D. Gunn. )

and inwards, a triangular, curved plate, forming the fore part of the outer wall of the
orbit, and articulating by its rough edge with the great wing of the sphenoid ;
between the sphenoidal and maxillary articulations there is frequently a small free
margin which closes the an terioi* extremity of the spheno-maxillary fissure. On the
orbital surface of this process are seen two grooves leading to small canals, the
temporal, opening on the temporal surface, and the malar leading to the facial surface
of the bone ; they transmit the two divisions of the temporo-malar branch of the
superior maxillary nerve.

Varieties. — The malar bone is rarely divided by a horizontal suture into an upper larger
and a lower smaller part. The small canals are subject to great variation ; they may begin
with a common opening on the orbital surface ; either may be double ; or one may fail
entirely. There is often a well marked projection at the upper part of the temporal border,
called the marginal inocess ; it gives attachment to a strong band of the temporal fascia.
In the numerous cases in which the malar bone does not enter into the formation of the
spheno-maxillary fissure, it is excluded either by the articulation of the great wing of the
sphenoid with the superior maxilla, or by a small Wormian bone.

THE NASAL BONE.

The nasal bones form the bridge of the nose. They are narrow and thick above,
but gradually become wider and thinner below. The superior border of each is
serrated, and articulates with the inner part of the nasal notch of the frontal bone :
the inferior is free in the dried skull, but in the recent state it gives attachment to
the lateral nasal cartilage ; it is generally marked by a small notch near its inner

THE LACHRYMAL BONE.

57

end. The external border is the longest, and articulates with the nasal process of
the superior maxilla, beins,- supported by small teeth which fit into depressions on
the edge of that bone. The internal border is thicker above than below, and meets
its fellow in the somewhat irregular internasal suture, which commonly deviates to
one side at the upper end : the two
bones form posteriorly a median crest,

FRONTAL BORDER

lAXILLARY

ASAL NERVE

which rests from above down upon the
nasal spine of the frontal bone, the ver-
tical plate of the ethmoid (fig. GG), and
the septal cartilage of the nose. The
anterior or facial surface is concave from
above down at its upper part, convex
below, and presents a small vascular fora-
men. The posterior or nasal surface is
rough for a short distance above, where it
rests upon the nasal process of the frontal
bone (fig. oS) ; in the rest of its extent it
is concave and smooth, being lined by the

mucous membrane of the nose ; and a little external to its centre it is traversed by
a small longitudinal groove w'hich lodges the nasal nerve.

Varieties. — The form and dimensions of the nasal bones vary greatly in different indi-
viduals. They are in general relatively large and prominent in the white races, small and
flat in the dark and yellow races. Fusion of the two bones, by obliteration of the internasal
suture, is occasionally, though rarely, met with : this condition is usual in ajje.':-.

Fig. 58. — Right nasal bone : A, inner view
B, OUTER VIEW. (Drawn by D. Gunn. )

LACH. CREST

CENDING PROC.

THE LACHRYMAL BONE.

The lachrymal lione, or os vngiiis, is a thin scale of bone placed at the
anterior and inner part of the orbit (fig. G9). It articulates above with the frontal
bone, behind with the orbital plate of the ethmoid,
and in front with the nasal process of the superior
maxilla.

The external surface is divided by a vertical ridge,
the lachrymal crest, into two parts : the anterior is
grooved, lachrymal groove, for the lachrymal sac, and
this part is prolonged inferiorly beyond the orbit as the
(lescencling proceas which assists in bounding the canal
of the nasal duct, and articulates with the inferior
tm'binate bone ; the posterior part, broader, is flat, con-
tinuous with the orbital surface of the ethmoid, and is
produced below into a hook-like projection, the hamidar
'/rrocesH, which curves forwards in the lachrymal notch of

the superior maxilla and bounds the orifice of the nasal duct on the outer side
(fig. GGJ. The internal surface superiorly completes some anterior ethmoidal cells,
and inferiorly looks into the middle meatus of the nose.

Varieties. — The lachrj-mal bone varies much in size : complete absence has been observed.
It is soniotimes perforated, or reticulate, or divided into two or more pieces. The hamular
process is often very small, and sometimes wanting. On the other hand it may be unusually
long, and reach the orbital margin, or (ven. in rare cases, extend slightly onto the face :
this represents a more largely develojied facial portion of the lachrymal bone in many
mammals. Occasionally the place of the hamular ])rocess is taken by a separate ossicle.
(Gegenbaur, Morph. Jahrb., vii. ; Macalister. Proc. Roy. Soc, bSSL)

Fig. 59. — Eight lachrymal
bone: outer a'iew. (Drawn
by D. Guiiii.)

58 THE BONES OF THE HEAD.

THE INFERIOR TURBINATE BONE.

The inferior turbinate or spongy bone is a slender lamina, attached by its
a^Dper margin along the lateral wall of the nose, and projecting into the nasal cavity,
so as to divide the middle from the inferior meatus. It is slightly involuted, its
convexity looking inwards, and its lower margin is free, somewhat thickened, and
]"olled upon itself. The attached margin articulates in its fore part with the inferior
turbinate crest of the superior maxillary bone, then ascends abruptly, forming the
lacJirymcd process, which completes the lachrymal canal and articulates with the

ETHM. PROCi,

B.

MAX. PROC. LACH. PROC.

ETHM PROC

Fig. 60. — Right inferior turbinate bone: A, inner view; B, outer view. (Drawn by D. Grunn.)

lachrymal bone ; behind this it is folded downwards in i\iQ maxillarij process, ioruimg
part of the inner wall of the antrum below the entrance into that cavity (fig. 69) ;
above and behind this, it presents a variable projection, the ethmoidal process, which
articulates with the uncinate process of the ethmoid ; and posteriorly it is attached
to the inferior turbinate crest of the palate bone. The posterior extremity is
elongated, sharp and pointed ; the anterior flattened and broader.

This bone is marked by irregular pits, grooves and canals for vessels, which are
directed for the most part longitudinally, but not, as the turbinal parts of the ethmoid
are, with vertical grooves for the olfactory nerves.

THE INFERIOR MAXILLARY BONE.

The lower jaw, inferior maxilla, mandible, is the thickest and strongest bone of
the face, and moves on the rest of the skull by means of a pair of condyles articu-
lating with the glenoid fossse of the temi^oral bones. It has the shape of an inverted
arch bent forwards upon itself, and consists of a middle larger nearly horizontal
part — the Z^orfy, and of two ascending branches or rami.

The body is marked in the middle hne in front by a faint vertical ridge, indicating
the symphysis or place of union of the originally separate lateral parts : this expands
l)elow into the triangular elevation of the chin, or menial protulerance, the base of
which is in well-marked bones slightly depressed in the centre, and prominent on
each side, forming the mental tuhercle. The superior or cdveolar border of the body
]s hollowed out into sockets for the teeth. The inferior border or lase is thick and
rounded, and projects beyond the superior. On the outer surface, on each side of
the symphysis, below the incisor teeth, is a shallow depression, the incisor fossa ; and
more externally is the mental foramen, placed midway between the upper and lower
borders, and under the interval between the two bicuspid teeth ; it is the anterior
opening of the dental canal, and transmits the mental nerve and vessels. Close below
the foramen is the somewhat indefinite external oUkiue line, running from the
mental tubercle backwards and upwards to the anterior margin of the ramus. The
deep surface is marked, on each side of the symphysis, along the inferior margin, by
an oval depression, indicating the anterior attachment of the digastric muscle.

THE IXFERIOR MAXILLARY BOXE. 59

Above this are the mental spmes, the lower being a small median ridge (often only a
slight roughness), to which the genio-hyoid muscles are attached, and the iij^per a
pair of more prominent tubercles, giving origin to the genio-glossi. Above the
upper spines a small median foramen penetrates the bone, and continued upwards
from this there is often to be seen a narrow groove marking the symphysis. Begin-
ning below the mental spines, and passing backwards and upwards to the ramus, is
:he prominent interned oblique line or mijlo-hfjoid ridge, which gives origin to the
mylo-hyoid muscle, and at its hinder end to a slip of the superior constrictor of the

Fig. 6L — The inferior maxillary bone, from the right side. (Drawn by D. Gunn.)

pharynx. Above this line is a smooth depression for the sublingual gland, and
more posteriorly beneath it another for the submaxillary gland.

The ramus is thinner than the body of the bone. Its posterior border in meeting
the line of the base forms the angle of the jaw, which is more or less rounded off,
and usually a little everted. The external surface is flat and impressed by the
masseter ; towards the angle irregular oblique ridges mark the attachment of
tendinous bundles of the muscle. The internal surface presents about its middle,
and on a level with the crowns of the lower molar teeth, the inferior dental foramen,
leading into the dental canal, which lodges the dental nerve and vessels. The inner
margin of the foramen is sharp and prominent anteriorly, forming the linguia.
Beginning at a notch behind the linguia is the mglo-ligoid groove (occasionally a
canal for a short sjiace), marking the passage of the mylo-hyoid nerve with com-
panion vessels : it runs downwards and forwards to the body of the bone, and
terminates below the hinder end of the mylo-hyoid ridge. Behind this, and reaching
down to the angle, is a marked roughness for the internal pterygoid muscle.

The ramus is surmounted by two projections, the condyle and the coronoid
process, which are separated by a deep excavation, the aigmoid nolrlt. The vondgle
is continued upwards from the posterior part of the ramus. It is su])portcd by a
constricted portion, the neck, oft the front of which is a depression for the insertion

60

THE BONES OF THE HEAD.

of the external pterygoid muscle. The condyle is a transversely elongated, convex
articular process, the major*axis of which is directed obliquely, so that if prolonged
it would meet with that of its fellow near the anterior margin of the foramen

Fig. 62. — Right half of the inferior maxillary boke, inner view. (Drawn by D. Gunn.)

magnum. The coronoid process is continued upwards, with a slight inclination
outwards, from the fore part of the ramus ; it is beak-shaped, and comi^ressed
from side to side ; by its sharp margins and somewhat roughened inner surface
it gives insertion to the temporal muscle.

The anterior border of the ramus is sharp and
smooth, extending from the coronoid process to the
posterior end of the external oblique line. To the
inner side of this border is a grooved surface, which
is bounded posteriorly by a ridge continued up from
the internal oblique line to the mesial aspect of the
coronoid process, and into which a part of the temporal
muscle is inserted. At the lower end of the groove, and
extending a short distance on the outer side of the
alveolar process, there is sometimes to be seen a slight
roughness marking the origin of the lower part of the
buccinator muscle.

Fi,

63. — Transverse section of
the lower jaw, passing
through the socket of the
last molar tooth. (g. d. t.)

The lower jaw consists of a very thick shell of dense
compact bone, enclosing cancellous tissue with slender tra-
becule. The dental canal lies close to the inner compact
layer, and nearer to the lower than the upper border of the
body : it has a thin wall of compact tissue, which becomes
cribriform in the fore part of its extent. From the main passage small channels pass
upwards to the sockets of the hinder teeth ; and beyond the mental foramen a prolongation
of the canal, with a less distinct wall, extends forwards, transmitting the nerves and vessels
to the canine and incisor teeth.

THE HYOID BONE. 61

The angle of the jaTv is in the adult usually about 120^ : in infancy it is as great as 140°
or more : in strongly developed jaws it may be diminished to 110° or less : and in old and
toothless jaws it is increased. These changes are connected with a variety of circumstances,
among which may be noticed. — the development of the temporary and permanent teeth, the
absorption of the alveolar arch after the loss of the teeth in advanced age, the elongation of
the face and upper jaw towards adult life, and the varying state of development of the
masseter muscles at different periods (see also p. 78).

THE HYOID BONE.

The hyoid bone, or os Ungwn, is situated at the base of the tongue, and may
be felt between the chin and the thyroid cartilage. It is shaped like the letter u,
and consists of a body and two pairs of cornua. It is suspended from the tips of
the styloid processes of the temporal bones h\ a pair of slender bands, the stylo-
hijoid ligaments, which in most animals form
distinct bones.

The hodg, or central piece, is compressed
from before backwards, and lies in a plane
directed doArnwards and forwards. Its anterior
surface is convex, and marked by a transverse
ridge, with a slight median projection, on each
side of which are depressions for muscular
attachments. Its posterior surface is concave,
and looks towards the epiglottis.

ThQ great cornua project backwards from the pj^,. c4.-The hvoid bone, from above
sides of the body. They are compressed from and before. (Drawn by D. Gunn. )
above down, are largest near their junction with
the body, and terminate behind in slightly expanded and rounded extremities.

The small cornua, or corninda, short and conical, project upwards and back-
wards from the places of junction of the body with the great cornua, and give
attachment at their extremities to the stylo-hyoid ligaments. They are commonly
in part, and not unfrequently entirely, cartilaginous.

The great cornua are connected to the body by synchondrosis, and after middle life usually
by bony union : the small cornua by a synovial articulation which is seldom anchylosed.
In some cases a synovial joint is formed also between the great cornu and body.

TEE SKULL AS A WHOLE.

THE SUTURES.

With the exception of the lowxn- jaw, which is moveably articulated with the
temporal bone, the bones of the skull are closely fitted together by more or less
uneven edges or surfaces, there being generally interposed only a small quantity of
fibrous ti.S8ue, continuous with the periosteum ; and to these lines of articulation
the name suture is given. At the base of the cranium, however, in young subjects,
the basilar process of the occipital is connected to the sphenoid, and the jugular
process to the petrous, by a thin layer of cartilage ; the articulation is therefore
synchondrosis, and when adult age is reached it becomes converted into bony union.

The sutures are best named from the bones between which they lie, as, occipito-
parietal, occipito-mastoid, fronto-ethmoidal, &c. Those around the parietal bones
are the longest and most regular, and to them special names have'bcen applied ;
thus, above, between the two parietal bones, is the sagittal or interparietal suture ;
posteriorly is the deeply serrated /am Jrfow/ or occipito-parietal suture; anteriorly is
the coronal or fronto-jjurietal suture, most markedly serrated in the middle part of

62 THE SKULL AS A WHOLE.

each lateral half, less so above where the frontal bone overlaps the parietal, and quite
simple at the lower end where the parietal overlaps the frontal ; inferiorly is the
temporo-parietal suture, consisting of two parts, the squamous suture, arched in form,
in which the squamous part of the temporal overlaps the parietal, and the parieto-
mastoid, short and serrated ; while at the antero-inferior angle is the short sjjheno-
parietal suture, about, half an inch in length, absent only in rare cases when the
frontal and temporal bones come into contact.

The cranial sutures are conveniently arranged in three groups, a median longitudinal, a
lateral longitudinal and a vertical transverse. The first consists of the sagittal suture, which
is continued in the infant, and frequently in the adult, by the frontal suture ; in the lateral
longitudinal are included, on each side, the fronto-nasal, fronto-masillary, fronto-lachiymai,
fronto-ethmoidal, fronto-malar, fronto-sphenoidal, spheno-parietal, squamous, and parieto-
mastoid sutures ; the third comprises the coronal and spheno-squamous, the lambdoid and
occipito-mastoid sutures ; and into this group also would fall the transverse articulations in the
centre of the base between the ethmoid, sphenoid and occipital.

After adult life is reached the bones of the skull evince a disposition to unite, and many of
the sutui'es thereby become closed ; but the period at which this commences, as also the order
in which it proceeds, are subject to great variations, so that the condition of the sutures
affords very little assistance in determining the precise age of a skull. The process com-
mences generally about thirty years of age ; the union takes place first on the inner
surface, and frequently the large sutures are quite obliterated internally while they are
perfectly distinct on the external surface. The earliest points to close are commonly the
part of the sagittal suture between the parietal fornaina, and the lower ends of the coronal
suture ; tlie more dentated parts of these sutures and the lambdoid follow later. The
squamous is very late in closing, and it is noteworthy that when the frontal suture fails to
unite at the usual time it may remain unchanged even to very advanced age. (Dwight,
" The Closure of the Cranial Sutures as a Sign of Age," Boston Med. and Surg. Joum.,
April, 1890.)

■Wormian bones. — Ossa triquetra, ossa sutiirarum. These are irregular ossifications,
found in many skulls, interposed between the cranial bones ; seldom iii the face. They are
of ii'regular form, with margins adapted to the character of the sutures in which they are
situated, and usually of small size ; but they may exceed an inch in diameter. Their most
frequent seat is in the occipito-parietal suture, where they sometimes occur in great numbers,
more or less symmetrically arranged : in some cases one or several bones of considerable size
occupy the place of the superior part of the occipital, more rarely of the antero-superior angles
of the parietal bones : a scale-like ossification is often seen between the antero-inferior angle
of the parietal and the great wing of the sphenoid [epijjteric lone, Flower). They are much
less frequent in the other sutures.

EXTEKNAL SURFACE OF THE SKULL.

The external surface of the skull may be conveniently divided into superior,
inferior, anterior, and lateral regions.

The superior region, extending from the supraorbital margins in front to the
superior curved lines of the occipital bone behind, and bounded laterally by the
temporal lines, is smooth and convex, covered only by the integument and by the
muscular fibres and aponeurosis of the occipito-frontalis muscle. The skull as seen
from above is of an oval form, broader in the parietal than the frontal region,
flattened in front, and projecting somewhat in the middle behind. There is also a
slight projection from the general curve at each of the frontal and parietal
eminences.

The anterior region of the skull, below the forehead, presents the openings of
the orbits, bounded by the frontal, malar, and superior maxillary bones ; and between
the orbits, the bridge of the nose, formed by the nasal bones and ascending processes
of the superior maxillaries. Below the nasal bones is the anterior nasal aperture, of
an inverted heart-shape : its thin margin gives attachment to the nasal cartilages,
and projects forwards in the middle line below as the anterior nasal spine. Below
the nasal aperture are the incisor fosste of the upper jaws ; below the orbits are the

EXTEllNAL SUKFACJE OF THE SKULL.

(ui

canine fossfe : and external to the canine fossae are tlie prominences of the cheeks,
formed by the anterior inferior parts of the malar bones. The lower jaw completes
the skeleton of the face. Tlie foramina in this region, on each side, are the snpra-
orbital foramen or notch in the superior margin of the orl)it, the infraorbital
foramen below the inferior margin of the orbit, the mental foramen of the lower jaw
and the small malar canal of the malar bone.

The anterior na-sal aperture is often markedly unsymmetricaL one half of the opeuin? being
broader and shorter, while on the other side it is narrower and moie deeply excavated below
Thi<! is associated with a corresponding deviation of the cartilag-inous part of the nose, which
points towards the side on which the wider half of the aperture is placed. (H. Welcker, •• Die
Asymmetrien der Xase und des Xasenskeletes,'" Stuttgart, 1S82.)

The orbits are pyramidal fosste, irregularly quadrilateral, Avith their bases
directed forwards and sliu'litlv outwards, their inner walls being nearly parallel, and

Fig. 65. — Front view of m.\lk skull at
ABuL'T TWESTV YEARS. (AUeu Thomson.) ^

1 . frontal eminence ; 2, glabella, between the
superciliary ri'iges, and above the transverse
suture of union witli the na.sal and superior
miixilhiry bones ; ::i, orbital arch near the
supraorbital notch ; 4, orbital surface of
great wing of sphenoid, between the sphe-
noiiial and the spheno-maxillary lissures :
5, anterior nnsdl aperture, within which are
seen in shadow the vomer und the turbinate
bones ; ti. superior maxillary bone at the
canine fossa — above the figure is the infra-
orbital foramen ; 7, incisor fossa ; 8, malar
bone ; 9. symphysis of lower jaw ; 10, mental
foramen ; 11, vertex, near the coronal suture ;
12, teniporal fossa ; 13, zygoma; 14, mastoid
jjrocess ; 15. angle of the jaw ; Iti, mental
pro'aiberance. In this skull there aie court een
teeth in each jaw, the wisdom teeth not having
yet appeared.

their outer walls diverging so as t(j

be nearly at right angles to each

other. The roof of each orbit is

formed by the orbital plate of the

frontal and the small wing of the

sphenoid ; the floor (tig. GO) by the

malar and superior maxillary bones,

and by the small orbital surface of

the palate bone at the back part ;

the inner wall (fig. G9) by the nasal

process of the superior maxilla, the lachrymal, the ethmoid and body of the

sphenoid ; and the outer wall by the orbital surfaces of the malar l)one and great

wing of the sphenoid. Tlie sphenoidal fissure (foramen lacerum orbitale) at

its inner extremity occupies the apex of the orbit, while its outer and narrower

part lies between the roof and the external wall. The optic foramen is internal

and superior to the sphenoidal fissure. In the angle between the external wall

and the floor is the spheno-vuu'illarij fissure, bounded by the sphenoid, palate,

superior maxillary, and malar Ijoncs, and leading into the spheno-maxillary fossa at

its back part, into the zygomatic fossa at its fore part. Passing forwards from the

margin of the spheno-maxillary fissure is the commencement of the infraorbital

c-anal, grooving the posterior part of the floor of the orbit. On the inner wall in

04

THE SKULL AS A WHOLE,

front is the lachrymal groove, fornaed by the superior maxillary and lachrymal bones
.nd leadino- into the nasal duct ; fartlier back, between the ethmoid and frontal
bones are "the anterior and posterior internal orbital cmuds ; on the roof, at its
anterior margin, is the supraorbital foramen or notch ; within the external angular
process is the' fossa for the lachrymal gland ; and in the outer wall are the temporal
and malar canals of the malar bone and one or two other minute foramina

The lateral region of the skull presents in succession from behind forwards
the mastoid process, the external auditory meatus, the glenoid fossa, with the condyle

Fig. 66. — Fore part of a horizontal section op the skull, passing through the centre of the

ORBIT. (G. D. T.)

The right half of the lower portion is represented.

of the lower jaw, the zi/ffomatic arch, formed by the zygomatic process of the temporal
bone and the posterior part of the malar, and internal to this the coronoid process of
the lower jaw. Above the zygomatic arch is the temporal fossa, below is the zygo-
matic fossa, the two being separated by the infratemporal crest on the great wing of
the sphenoid (fig. 68).

The temporal fossa is occupied by the temporal muscle, and the squamous
part of the temporal, the parietal, frontal, sphenoid and malar bones take part in its
formation. It is bounded above by the temporal crest of the frontal bone and the
lower temporal line of the parietal. The latter turns down posteriorly to join the
sapramastoid crest of the temporal bone, which in front is continued into the upper
edge of the zygomatic arch. Along this line of bone is attached the temporal fascia,
which in the complete state roofs in the temporal fossa.

The zygomatic or infratemporal fossa (fig. 68) is an irregular hollow, in part
covered by the ramus of the lower jaw. Its wall is formed internally by the external

ZYGOMATIC FOSSA.

65

pterygoid plate ; superiorly by the lower part of the great wing of the sphenoid, in which
are seen the foramen ovale and foramen spinosum, and by a small part of the squamous
of the temporal ; and anteriorly by the zygomatic surface of the superior maxilla,
presenting the orifices of the posterior dental canals, together with the lower part of
the malar bone. Inferiorly, the external pterygoid plate approaches closely the
superior maxillary bone, but the two are usually prevented from meeting by a thin
portion of the pyramidal process of the palate bone ; superiorly, they are separatee
by the pterijyo-maxiHanj fissure, a vertical slit leading above into the spheno-

Fig. 67. — Lateral view of the skull represented in figure 65. (Allen Thomson.) ^

1, frontal bone ; 2, parietal bone at the upper temporal line ; x x , coronal sutui-e ; 3, on the
occipital bone at the lower end of the lambdoid suture, near its meeting with the occipito-mastoid and
parieto-ma.stoid sutures ; 3', external occipital protuberance ; 4, great wing of sphenoid ; 5, squamous
part of temporal ; 6, the same at the root of the zygoma, immediately over the external auditory
meatus ; 7, mastoid portion of temporal, at the front of which is the mastoid process ; 8, left condyle of
occipital bone ; 9, anterior nasal aperture ; 10, on the lachrymal bone in the inner wall of the orbit ;
11, malar h»one, near its junction with the zygoma ; 12, superior maxillary bone behind the canine
fossa ; 13, ramus of the lower jaw ; 14, body of the lower jaw, near the mental foramen.

maxillary fossa, and closed internally by the veitical plate of the palate bone. At
the upper part of the zygomatic fossa the horizontal spheno-maxillary fissure leads
into the orbit.

The spheno-maxillary fossa is the space which lies in the angle between the
pterygo-maxillary and the spheno-maxillary fissures. It is bounded behind by the
pterygoid process and the lower part of the anterior surface of the great wing of the
sphenoid bone ; in front by the 8U])erior maxillary bone ; and internally by the
vertical plate of the palate bone with its orbital and sphenoidal processes. Into this
nan-ow space five foramina open, viz., on the posterior wall, the foramen rotundum,
the Vidian canal, and, between the sphenoidal process of the palate bone and the root
of the internal pterygoid plate, the pterygo-palatine canal ; on the inner wall, the

66

THE SKULL AS A WHOLE.

INFRAORS. GROOVE
PTERVCO-MflX. riss.

NO-MAX. ri!

Fig. 68. — Side view of the lower and fore part of the skull, the inferior maxilla and

ZYGOMATIC ARCH BEING REMOVED, TO SHOW THE ZYGOMATIC FOSSA. (Gr. D. T.)

OPTIC FOR.

LACH BONE
.LACH cfloove

NASILDUCT

PTERYCO^MAX. FISS,

Fig. 69. — Sagittal section op the facial portion op the skull. (G. D. T.)

The section passes through the right orbit a little internal to the centre, and opens up the antrum
and spheno-maxillary fossa.

EXTERNAL BASE OF THE SKULL.

67

spheno-palafcine foramen formed by the palate bone and the sphenoid, and opening
into the nasal cavity ; and interiorly, the posterior palatine or palato-maxillary
canal, which leads down to the roof of the mouth between the palate and superior
maxillary bones.

The external base of the skull, excluding the lower jaw, is divisible into
three parts, anterior, middle, and posterior.

The anterior division consists of the palate and the alveolar arch. It is
traversed longitudinally by a median suture, and transversely by that between the
maxillary and palate bones. Anteriorly, in the middle line, is the anterior palatine

Fig. 70. — EXTEUXAL BASE OF THE SKULL

SHOWN IX FiGCRE 65. (Alleii Thomson.) i

1, palate plate of the superior maxil-
lar}' bone ; 2. palate plate of the palate
bone : 3, anterior palatine fossa ; 4, is
placed outside the posterior palatine canal,
inside the tuberosity of the superior
maxilla, and in front of the smaller poste-
rior palatine canals ; 5, inner surface of
the external pterygoid plate ; 6, is placed
■within the posterior opening of the right
nasal foss:i on the internal pterygoid plate;
7, vomer : x , po.sterior opening of the
pterygo-palatine canal in front of the
foramen lacerum ; 8, spheno-maxillary
fissure leading into the orbit ; 9, foramen
spinosum ; 10, foramen ovale ; 11, placed
on the apex of the petrous Ijone, between
the foramen lacerum and the inferior
opening of the carotid canal ; 12, jugular
foramen ; 13, articular eminence of the
temporal bone ; 14, external auditory
meatus ; 15, glenoid fossa in front of the
fissure of Glaser ; 16, tymjianic plate or
posterior part of the glenoid fossa, close
to the styloid process, behind which is
.seen the stylo-ma.stoid foramen ; 17, mas-
toid process, and to its inside the digas-
tric and occipital grooves ; 18, basilar
proces-s of the occipital bone, and iu front
the mark of the still incomplete union with
the bod}' of the sphenoid bone ; 19, con-
dyle of the occipital bone ; 20, is placed
in the foramen magnum, and points to
the inner opening of the anterior con-
dylar loramen ; 21, po.sterior condylar

foramen ; 22, jugular process of the occipital bone : 23, external occipital crest running down from the
protuberance ; 24, superior curved line of the occipital bone ; 25, 26, inferior curved line.

fossa, with the four foramina opening into it (p. 52) ; posteriorly, on each side,
at the base of the alveolar arch, is the opening of the posterior palatine canal,
from which the palatine groove, lodging the large palatine nerve and vessels,
runs forwards ; and farther back, on the under aspect of the tuberosity of the palate
bone, are the apertures of the posterior and external small palatine canals. The palate
is surrounded in front and on the sides by the alveolar arch bearing the teeth of the
upper jaw.

The middle division extends back to the front of the foramen magnum. Its
central ])ortion has been called the niilhiral fossa. In the middle line is the basilar
])roces8 of the occipital bone, and in front of that the body of the sphenoid, covered
anteriorly Ijy the ala3 of the vomer. On each side, the petrous portion of the
temporal bone reaches as far forwards as the extremity of the basilar process ; and

F 2

Qi TtlE SKULL AS A WHOLE.

between the petrous and squamous portions is the back part of the great wing of the
sphenoid bone. Between this division of the base of the skull and the palate are
the posterior nares, separated by the vomer, and bounded above by the body of the
sphenoid bone, below by the horizontal plates of the palate bones, and laterally by
the internal pterygoid plates. On each side of the posterior nares is the pterygoid
fossa, completed below by the tuberosity of the palate bone ; and a line from the
external pterygoid plate to the spine of the sphenoid forms the division between this
reo-ion and the zygomatic fossa. Immediately behind or internal to this line is the
groove for the cartilaginous part of the Eustachian tube, formed by the margins of
the great wing of the sphenoid and the petrous, and leading to the osseous part of the
tube in the temporal bone. Between the apex of the petrous, the basilar process,
and the sphenoid is the foramen lacerum ; in a line proceeding backwards and out-
wards from this are the free surface of the petrous, the lower orifice of the carotid
canal, the vaginal and styloid processes, and the stylo-mastoid foramen ; while
internal to these are the jugular and anterior condylar foramina.

Between the basilar process of the occipital bone and the petrous portion of the temporal
is an irregular cleft, extending- from the foramen lacerum backwards and outwards to the
jugular foramen, and called the petro-hasilar fissure. This interval, tog-ether with the lower
part of the foramen lacerum, is filled in the recent state by fibrous tissue which often
contains one or two small Wormian ossicles. In front of the petrous portion, at the bottom
of the groove of the Eustachian tube, is the petro-S])henoidal fissure, also continued outwards
from the foramen lacerum.

The posterior division presents on each side of the foramen magnum, from
within outwards, the occipital condyle, the under surface of the jugular process, the
occipital groove of the temporal bone, the digastric fossa, and the mastoid process.
Behind the foramen magnum is the tabular part of the occipital bone, with its ridges
and muscular impressions.

THE INTEEIOR OF THE CRANIUM.

The wall of the cranium consists of two layers of compact bony substance, the
outer and inner tables, and an intervening cancellated substance, called dvploe. The
inner or vitreous table has a smooth, close-grained, shining appearance, is hard and
brittle, and presents irregular digitate impressions corresponding to the convolutions
of the cerebrum. The thickness of the skull-cap or calvaria is fairly uniform, and
generally ranges from one-sixth to one-fourth of an inch : it is somewhat increased
along the middle line, especially in front and behind, and diminishes below on each
side, in the temporal fossa. The base of the skull varies greatly in this respect:
the thickest parts are the basilar process, the petrous and mastoid portions of the
temporal bones, and the occipital bone at the protuberances and ridges. The
thinnest portions of the cranial wall are the cribriform plate of the ethmoid and the
orbital plates of the frontal bone, in both of which the diploe is absent ; the bone is
also thin and compact in the middle part of the inferior occipital fossse, and in the
lower part of the squama and the glenoid fossa of the temporal.

The upper part of the cranial cavity is enclosed by a single vaulted dome, formed
by the frontal, parietal, and occipital bones. This is marked on its internal surface
by the groove for the superior longitudinal sinus, by shallow cerebral impressions, by
small ramified meningeal grooves, and by Pacchionian fossae of varying depth. The
only apertures in the roof of the skull are the inconstant parietal foramina, which
open by the side of the longitudinal sulcus posteriorly ; they give passage to emissary
veins, and occasionally a branch of the occipital artery.

The internal base of the skuU is divided into three fossse, named anterior,
middle, and posterior.

INTERNAL BASE OF THE SKULL.

69

The anterior fossa, formed by the orbital plates of the frontal bone, the
cribriform plate of the ethmoid, and the small wings and part of the body of the
sphenoid, supports the frontal lobes of the cerebrum. It is convex laterally above
the orbits, but sinks into a hollow over the cribriform plate of the ethmoid, in the
middle line of which the crista galli stands up, separating the deep olfiictory grooves
for the reception of the olfactory bulbs. In front of the crista galli is the foramen

Fig. 7L-

-Sagittal section of the adult skull a little to the left of the median plane.
(Allen Thomson.) ^

1, nasal bone ; 2. perpendicular plate of the ethmoid with olfactory foramina and gi-ooves at its
upper part : 3, vomer ; 4, right superior maxillary bone, forming part of the wall of the right nasal
fossa ; below this is the anterior extremity of the right inferior turbinate bone overhanging x , whicli
is the right inferior meatus of the nose ; 5, crista galli ; 6, inner surface of the frontal bone ; 7, of the
parietal bone ; 8, squamous jjart of the temjioral ; 9, on the occipital bone below the internal occipital
protuberance ; 10, external occipital protuberance ; 11, on the condylar process lielow the a.nterior con-
ilylar foramen ; 12, on the jMsterior surface of the petrous below the internal auditory meatus ; between
9 and 12. the groove of the right lateral sinus; 13, placed above the sella turcica; 14, left frontal
sinus ; 15, left sphenoidal sinus, the figure being placed on the sphenoidal septum ; 16, hard palate
and alveolar arch — the figure is placed near the lower opening of the posterior palatine canal, and the
grooves which extend forwards from it ; 17, anterior nasal spine ; 18, section of the left superior
maxillary bone, and near the jjlace to whicli the line points, the section of the anterior palatine fossa ;
19, on the inner surface of the ramus of the lower jaw, below the sigmoid notch, and above the inferior
dentjil foramen ; 20, inner surface of the body of the jaw on the mylo-hyoid ridge ; 21, surface of section
of the lower jaw to the left of the symphysis ; behind the symphysis, and between 21 and 22, the mental
ST>ines ; 23, mylo-hyoid groove.

caecum ; on each side are the numerous apertures of the cribriform plate, the inner
openings of the internal orbital canals, and the foramen by which the nasal nerve
passes into the nose.

The foramen cascum sometimes conveys a vein passing- from the nose to the superior lonfjri-
tudinal sinus. The apertures of the cribriform plate are occupied by the olfactory nerve
filaments. Throug-h the anterior internal orbital canal the nasal nerve and the anterior
ethmoidal art<;ry entfjr the skull, and through the posterior, which is less constant, the
posterior ethmoidal artery. The foramen for the exit of the nasal nerve is at tlie front

70

THE SKULL AS A WHOLE.

of the cribriform plate, usually between that and the frontal bone, and is connected by a ji'roove
with the inner opening of the anterior internal orbital canal : the nerve is accompanied by the
nasal division of the anterior ethmoidal artery.

The niiddle fossa, on a lower level than the anterior, consists of a median and

two lateral parts. The median part is small, being formed by the olivary eminence

and sella tm-cica of the sphenoid bone, and limited behind by the dorsum &e\lse. The

lateral part on each side, formed by the great wing of the sphenoid, the squamous

part, and the anterior surface of the petrous part of the temporal, lodges the temporal

lobe of the cerebrum. The foramina of the middle fossa are the optic foramen,

sphenoidal lissure, foramen rotundum, foramen ovale, foramen spinosum, foramen

laeerum and hiatus Fallopii.

Fig. 72. — Internal base op the
SKULL. (Allen Thomson.) {r

1, anterior fossa and roof of tlie
orbit, as formed by the frontal bone ;
between 2 and 3, the foramen caecum,
crista galli and cribriform plate of
etlnnoid ; 3, ethmoidal spine of the
sphenoid ; 4, lesser wing of sphenoid
terminating posteriorly in the anterior
clinoid process, inside which is the
optic foi'amen ; .5, placed in the pitui-
tary fossa, behind the olivary emin-
ence and transverse groove of the
optic commissure ; 6, dorsum sellte,
terminating in the posterior clinoid
processes ; 7, foramen rotundum, in
front of which, but not seen in the
figure, is the sphenoidal fissure ; 8,
foramen ovale ; 9, foramen spinosum ;

10, on the petrous bone, near its apex,
and to the inside of the hollow occu-
jiied by the Gasserian ganglion ; in
front of this is the foramen laeerum ;

11, in front of the eminence of the
superior semicircular canal, and be-
hind the hiatus Fallopii ; 12, upper
border of the petrous, marked l>y the
suiierior petrosal gi'oove ; 13, the
posterior surface of the petrous— to
the inside, the internal auditory
meatus, behind, the scale of bone
covering the aqueduct of the vestibule ;
14, basilar groove ; 15, anterior con-
dylar foramen ; 1(\ jugular foramen ; 17, groove of the lateral sinus ; IS, internal occipital protube-
rance, and running down from it the internal occipital crest ; between 17 and IS, the upper part of the
groove of the lateral sinus, between 17 and 16, the lower part ; 19, cerebellar fossa.

Thi-oug-h the optic foramen the optic nerve and the ophthalmic artery enter the orbit. The
sphenoidal fissure (foramen laeerum anterius) also opens into the orbit ; it gives passage to
the third, fourth, ophthalmic division of the fifth, and the sixth nerves, and the ophthalmic
veins. By the foramen rotundum the superior maxillary nerve passes into the spheno-max-
illai-y fossa. The foramen ovale and foramen spinosum lead into the zygomatic fossa : the
former transmits the inferior maxillary nerve, the small meningeal artery, and two or three
emissary veins ; the latter, the large meningeal vessels.

The foramen, laeerum (medium) is an irregular aperture between the apex of the petrous
and the body and great wing of the sphenoid, and in the recent state is closed below by a mass
of fibrous tissue : the carotid canal opens on its external wall, the Vidian canal anteriorly.
The lingula projecting backwards from the body of the sphenoid effects a partial, sometimes
a complete subdivision of the space : by the inner part the carotid artery enters the cranial
cavity .• and through the external, the large superficial petrosal nerve, coming from the hiatus
Fallopii, reaches the posterior orifice of the Vidian canal.

The posterior fossa, deeper and larger than the others, extends back to
the occipital protuberance, and lodges the cerebellum, medulla oblongata and pons.

THE INTERIOR OF THE CRANIUM. 71

The occipital bone, the petrous and mastoid portions of the temporal, the postero-
inferior angle of the parietal, and the body of the sphenoid take pait in its formation.
In the centre of the fossa is the foramen magnum ; and on each side of this, in
a nearly vertical line from below upwards, are the anterior condylar foramen piercing
the condylar portion of the occipital bone, the jugular foramen between the occipital
and petrous, and the internal auditory meatus on the posterior surface of the petrous.
Behind the jugular foramen is the posterior condylar foramen (if present), and higher
up the more constant mastoid foramen, both opening into the groove of the lateral
sinus.

The foramen magnum is occupied in the recenb state by the lower end of the medulla
oblongata with its membranes, the vertebral arteries, and the spinal accessory nerves. The
anterior condylar foramen transmits the li^'poglossal nerve and a meningeal branch of the
ascending pharyngeal artery. By the internal auditory meatus the facial and auditory nerves,
with the portio intermedia and the auditory vessels, leave the cranial cavity. The posterior
condylar and mastoid foramina transmit emissary veins, the latter also the mastoid branch of
the occipital artery.

The jugular foramen (foramen lacerum posterius) is formed by the jugular notches of the
petrous and occipital bones : somewhat pyriform in shape, two more or less marked constric-
tions indicate a division into three compartments ; most externally and posteriorly is a large
rounded part in which the lateral sinus joins the internal jugular vein ; the middle part, cor-
responding to a distinct notch in the lower border of the petrous, transmits the glosso-
phaiyngeal, vagus, and spinal accessory nerves ; and the most anterior and internal, sometimes
completely separated by a spiculum of bone (the intrajugular process ; p. 34), gives passage to
the inferior petrosal sinus. A meningeal branch of the ascending pharyngeal or occipital
artery also enters the skull by the posterior compartment.

Grooves for blood-vessels. — The groove of the middle meningeal artery
commences at the foramen spinosum, and ramifies principally on the squamous
portion of the temporal bone and on the parietal. The groove of the internal
carotid artery lies on the side of the body of the sphenoid, and extends from
the ibramen lacerum to the inner side of the anterior clinoid process. The groove of
the superior longitudinal sinus, commencing at the frontal crest, passes backwards in
the middle line of the roof of the skull, and terminates at the internal occipital
protuberance. From that point the groove of the lateral sinus passes outwards on
each side over the occipital bone, crosses the posterior inferior angle of the parietal
bone, descends on the mastoid portion of the temporal bone, runs inwards again on
the occipital, and turns forwards to terminate at the jugular foramen. The groove
of the inferior petrosal sinus lies between the petrous portion of the temporal bone
and the basilar process ; that of the superior petrosal sinus extends along the superior
edge of the petrous portion.

THE NASAL CAVITIES AND COMMUNICATINa AIK-BINUSES.

The nasal cavities, or fossae, are placed one on each side of a median vertical
septum. They open in front by the anterior nasal aperture and behind by the
posterior nares already described, and communicate with the sinuses of the frontal,
ethmoid, sphenoid, and superior maxillary bones. Their vertical extent, as well as
that fi'om before backwards, is considerable, but their transverse width is veiy
limited, especially in the upper part.

The internal wall, or septum nasi, is formed by the central plate of the ethmoid,
the vomer, the nasal spine of the frontal, the rostrum of the sphenoid, and the crests
of the nasal, maxillary, and palate bones. It presents a great angular deficiency in
front, which in the recent state is filled up by the septal cartilage. In most cases it
deviates somewhat from the middle line to one side or the other.

The roof is horizontal in its middle part, but sloped downwards before and
behind. The middle part is formed by the cribriform plate of the ethmoid, the fore

73

THE SKULL AS A WHOLE.

part by the frontal and nasal bones, and the back part by the body of the sphenoid,
the ala of the vomer and the sphenoidal process of the palate bone. In it are the
apertures of the cribriform plate and the orifice of the sphenoidal sinus.

The floor, formed by the palate plates of the maxillary and palate bones, is smooth,
and concave from side to side. Towards its anterior extremity is the orifice of the
incisor foramen.

The external ivall is the most extensive. The bones which take part in its
formation are the nasal, superior maxillary, lachrymal, ethmoid, inferior spongy, and
palate bones, and the internal pterygoid plate. The superior and inferior turbinate
processes of the ethmoid bone, and the inferior spongy bone, projecting inwards,
overhang the three hollows called meatuses. The superior meatus, very short,
is placed between the superior and inferior turbinate parts of the ethmoid ; into it

Fig. 73. — Sagittal section of a paet of the

SKULL, SHOWING THE OUTER WALL OF THE LEFT

NASAL FOSSA, &c. (Alien Thomson.) \

1, nasal bone ; 2, nasal process of the supe-
rior maxillary bone ; 3, vertical plate of the
palate bone ; 4, superior turbinate bone — below
it the superior meatus, behind it the spheno-
ethmoidal recess and the opening into the left
sphenoidal sinus ; 5, middle turbinate bone —
below it the middle meatus, into which opens
the maxillary sinus ; superiorly and anteriorly,
is the opening of the infundibulum ; behind it,
and above 3, the spbeno-palatine foramen ;
6. inferior turbinate bone — below it the inferior
meatus x x ; below these marks the section
of the palate plates of the left palate and supe-
rior maxillary bones ; 7, left frontal sinus ; 8,
left sphenoidal sinus ; 9, left optic foramen in
the root of the lesser wing of the sphenoid, and
anterior clinoid process ; 10, dorsum sellae di-
vided ; and between 9 and 10, the sella turcica ; 11, posterior surface of the petrous, close to the
internal auditory meatus ; 12, basilar process of the occipital bone, close to the jugular foramen ;
13, on the occipital condyle, below the anterior condylar foramen ; 14, styloid process ; 15, external,
and 16, internal pterygoid plates ; 17, posterior palatine canal.

open anteriorly the posterior ethmoidal cells, and posteriorly the spheno-palatine
foramen. The middle meatus, the space between the inferior turbinate part of the
ethmoid and the inferior spongy bone, communicates with the anterior and middle
ethmoidal cells, with the maxillary sinus, and at its fore part, by means of the
infundibulum, with the frontal sinus. The inferior meatus, longer than the others, lies
between the inferior spongy bone and the floor of the nasal cavity, and in its fore
part is the orifice of the nasal duct. Above the superior meatus, in an angle
of the roof formed by the cribriform plate and the front of the body of the sphenoid
(fig. 73, behind 4), is a depression called the spheno -ethmoidal recess (Gr. H. Meyer),
formed by the narrowing of the lateral mass of the ethmoid (fig. 66) ; on the
posterior wall of the recess is the opening of the sphenoidal sinus.

The air-sinuses are hollows within the ethmoid, fi'ontal, sphenoid, and maxillary
bones, which communicate with the nasal cavities by narrow orifices. With
tne exception of the maxillary sinus these cavities are absent in, the infantile skull.
The maxillary sinus begins to be formed about the fourth month of foetal life ; the
frontal, ethmoidal and sphenoidal first excavate the respective bones during child-
hood, but remain of small size up to the time of puberty, when they undergo a great
enlargement.^ In advanced life they all increase in size by absorption of the
cancellated tissue in their vicinity. The ethmoidal sinuses consist of several irregular
spaces occupying the lateral mass of the ethmoid, and completed by the frontal,

OSSIFICATION OF THE BONES OF THE HEAD.

73

sphenoid, lachrymal, superior maxillary and palate bones. The anferior and middle,
the larger and more numerous, open into the middle, the 'posterior into the superior
meatus. The frontal sinuses are placed between the outer and inner tables of
the frontal bone over the root of the nose. They extend outwards from behind the
glabella to a variable distance over the orbit, being separated from each other by a
thin bony septum. They open on each side into the middle meatus of the nose
through the inf undibulum. The sphenoidal sinuses occupy the body of the sphenoid,
being formed in connection with the sphenoidal spongy bones. They are separated
by a median septum, and open into the spheno-ethmoidal recess. The maxillary
sinus has been described in connection with the superior maxillary bone ; it opens by
a small aperture into the middle meatus.

The air-spaces of the temporal bone (tympanum and mastoid cells) are described in connec-
tion with the Anatomy of the Ear in Vol. III.

OSSIFICATION OF THE BONES OF THE HEAD.

The ossification of the bones of the base of the cranium takes place for the most part in car-
tilap'e. and in each case proceeds from several centres which represent distinct bones in lower
vertebrate forms ; the bones of the roof are simpler in their develoi^ment, and originate in

Fis.

-Ossification of the occipital
BoxE. (R. Quain.)

A, in a fcetus of 10 weeks (from Meckel) ;
a, tabular part ; 1 & 2, lower and upper pairs
of centres ; b, lower jjart or basilar and con-
dylar portions : ossific centres are seen in the
condylar ijortions.

B, occipital bone at birth ; a, tabular
part, in which the four centres have become
united into one, leaving tissures between
them ; b, b, condylar portions ; c, basilar
portion.

membrane : those of the face are also deposited in membrane, with the exception of the
inferior turbinate bone and a small part of the lower jaw. In the expanded tabular bones the
ossification spreads outwards from the centres, and the marginal portions, in the earlier stages,
present more or less the form of radiated fibres or spicula. At birth the sutural edges, and
especially the angles, are incomplete, the bones being united and the interspaces filled up by
fibrous tissue. The diploe and air-sinuses are at first absent, some of the latter arising early in
life, and others being fonned at a comparatively late but variable period.

The occipital bone at birth consists of four separate pieces — a basilar, a tabular, and two
condylar parts, united by intervening cartilage. The lines of junction of the basilar and
condylar parts pass through the condyles near their anterior extremities ; those of the condylar
and tabular parts extend out^\•ards from the posterior margin of the foramen magnum. The
basilar (fMixiocripif/il) and condylar parts (croccipif/th') arise each from one osseous nucleus,
which appears from the eighth to the tenth week.' In the tabular part there appear, a few
days earlier, usually four nuclei, an upper and a lower pair ; these speedily unite, but leave
fissures running in from the upper and lateral angles, which remain for some time after
birth. The upper pair of these differ from the other centres of this bone in being deposited in
membrane, and while the lower portion of the tabular part is the proper mijmioccijjittil element,
the upper represents the intcrparictid bone of many animals ; it occasionally happens that this
remains distinct in the human skull, the upper part of the occipital squama being separated
from the rest by a suture running transversely from one lateral angle to the other, and by no
means unfrequently a partial division exists, by persistence of the lateral fissures, which may

' In the descriptions of the mode of ossification of the bones, weeks and months refer always to
periods of foetal life.

74

THE SKULL AS A WHOLE.

even simulate fracture. The osseous union of the supra- and exoccipitals, beginning in the
second or third, is completed in the fourth year ; that of the basi- and exoccipitals, beginning
in the third or fourth, is completed in the fifth or sixth year. The basioccipital is united to
the basisphenoid by intervening cartilage up to about the twentieth year, after which ossific
union begins and is completed in one or two years.

The parietal bone begins to ossify in membrane in the seventh week. According to Toldt ^
it has two nuclei, an upper and a lower, which speedily fuse into a single mass occupying the
position of the future parietal eminence. The radiating ossification extends in such a way as
to leave a notch or cleft at the upper part of the bone a little distance from the posterior
angle, giving rise to the scujUtal fontandlc — a space between the two bones, which gradually
becomes closed in during the latter half of foetal life. Traces of the fontanelle are often to be
recognized at the time of birth ; and the parietal foramina are remains of the interval." In rare
cases a transverse _^7fl?7c^«i/s.>-?«'e persists. The parietal eminence is very conspicuous in the
young bone, and gives a marked character to the form of the skull for a number of years in
early life.

The frontal bone is ossified from two nuclei which appear, one on each side above the orbital
arch, about the seventh Aveek. At birth the bone consists of two separate lateral portions,
which meet in a vertical median suture during the first year. This frontal iiiture usually

Fig. 75. — Frontal bone op a fcetus shortly
BEFORE BIRTH. (R. Quain. )

a k, b indicate the two portion.? of the bone,
in each of which the radiation of bony spicula
from the frontal eminence is seen.

Fig. 76. — Skull of a child at birth, from
ABOVE. (Leishman.j -3

a, anterior fontanelle ; j;, posterior fon-
tanelle ; b, b, parietal eminences ; for the lateral
fontanelles, see fig. S3, p. 82.

becomes obliterated by osseous union taking place from below upwards, during the second
year, though not unfrequently it persists throughout life (p. 39). The frontal sinuses appear
about the seventh year, and continue to increase in size up to old age.

Fontanelles. — These are membranous intervals between the incomplete angles of the
parietal and neighbouring bones, in some of which movements of the soft wall of the cranium
may be observed in connection with variations in the state of the circulation and respiration.
They are six in number, two median, anterior and posterior, and four lateral. The antarior
fontanelle, situated between the antero-superior angles of the parietal bones and the superior
angles of the ununited halves of the frontal bone, is quadrangular in form, and remains open
for some time after birth. The poaterlor fontanelle. situated between the postero-superior
angles of the parietal bones and the superior angle of the occipital bone, is triangular in shape.
It is filled up before birth, but the edges of the bones, being united by membrane only, are
still freely moveable upon each other. The lateral fontanelles, small and of irregular form,
are situated at the inferior angles of the parietal bones. The fontanelles are gradually filled
up by the extension of ossification into the membrane which occupies them, thus completing
the angles of the bones and forming the sutures. The closure, especially of the posterior and
lateral, is often assisted by the development of Wormian bones in these situations. All traces
of these unossifled spaces disappear before the age of four years. The sagittal fontanelle,
existing before birth, has been noticed above.

The temporal bone in the later stages of fcetal life consists of three principal pieces, the
squamo-zygomatic, petro-mastoid or periotic, and tympanic. The squamo-zygomatic is ossified
in membrane from a single nucleus, which appears in the lower part of the squamosal about
the seventh or eighth week, and extends upwards into the squamosal, and outwards into the
zygoma. From the hinder part of the squamosal a considerable postauditory proceHS grows
downwards below the supramastoid crest, separating the tympanic from the periotic, and

^ "Lotos, Jahrbuch f. Naturvv.," 1882.

" Broca, Bull. Soc. Anthrop. de Paris, 1875 ; Augier, " Rech. sur le developpement des parietaux
a la region sagittale," Tliese, Paris, 1875.

OSSIFICATION OF THE BONES OF THE HEAD. 75

forming the upper and fore part of the mastoid division of the bone. Beneath this isi an air-
space continued backwards from the tympanum, and called the a/ifrinn m(ii<toidcv in. from
which the mastoid cells subsequently grow out. During the third month an osseous nucleus
appears in the lower part of the external membranous wall of the tympanum, and extends
upwards forming the ti/nipdiiic viiuj. an imperfect circle, open above, which encloses the
tympanic membrane. Before birth the extremities of this ring become united with the
squamo-zygomatic.

Pctro-maxtold or pcrtofic. It is only in the latter half of the fifth month that osseous
deposits begin to be formed in the cartilaginous ear-capsule. They extend rapidly, and the
different ossifications are united by the end of the sixth month. The first to appear is a
nucleus on the promontory (^opixt/iofic), which spreads round the fenestra rotunda, and forms
the portion of the petrous below the internal auditory meatus and fenestra ovalis. The second
(proof ic) arises over the superior semicii-cular canal, and forms most of the petrous seen in the
interior of the skull, as well as the upper and inner part of the mastoid : it furnishes the upper
boundai-ies of the internal auditory meatus and fenestra ovalis. A little later, a third nucleus

Fig. 77. — Separate parts of the temporal bone of a fcetus

SHORTLY BEFORE BIRTH. (R. Quain. )

a, squamo-zvgomatic ; b, tympanic : c, mastoid part of periotic ;
d, inner wall of tympanum ; c, ma.stoid antrum.

{cj)iofic). which is occasionally double, is developed in con-
nection with the posterior semicircular canal, and extends
into the lower part of the mastoid. According to Sutton
the tegmen tympani and covering of the external semi-
circular canal are formed by a separate os.sification ( jjfcrofic),
appearing aboii.t the same time as the prootic. Vrolik also
described a special nucleus for the roof of the cochlea, and
another in connection with the common crus of the superior
and i^osterior semicircular canals. (Huxley, '• Lectures on

Comparative Anatomy," 1864 ; Vrolik, Niederl. Arch, f . Zoologie. i, 291 ; Sutton. Journ.
Anat., xvii. ¥JS.)

At birth the petro-mastoid is separated from the squamosal by a thin plate of intervening
cartilage, bony union taking place during the first year ; the mastoid portion also is flat, the
glenoid fossa shallow, the articular eminence scarcely to be seen, and the tympanic ring and
membrane are even with the outer surface of the bone. The anterior and inferior walls of
the external auditorj' meatus consist at first of fibrous tissue, in which the tympanic plate is
formed after birth.' The latter is develo]ied from the outer margin of the slender tympanic
ring, commencing in the form of two .small tubercles at the fore and hinder parts respectively ;
these increase in size and meet in the floor of the meatus, enclosing a foramen which is
gradually closed. The foramen is completed as a rule in the second year, and is seldom
obliterated before five years of age. The part of the wall of the meatus which was occupied
by the foramen is commonly thin, and sometimes a small aperture persists through life.
On the posterior sm-face of the petrous at birth is a considerable depression which extends into
the arch of the superior semicircular canal, and represents the floccular fossa of the lower
animals ; in the adult bone a vestige of this is always present as a small fissure above and
outside the internal auditoiy meatus, between that and the aqueduct of the vestibule. The
mastoid process is developed about the second year, but the air-cells are not formed till near
puberty.

The styloid process is formed by two small ossifications in cartilage — the tj/nipaiio/ii/al
at the base, commencing before birth and speedily joining the bone, and the .ifi/lo/ii/til
commencing usually after birth, but remaining very small until the period of puberty ; this
only joins after adult age is reached, and often remains iiennanently separate. (Flower, Brit.
Ass. Rep., 1870.)

The sphenoid bone is divided in the fcetus into a posterior ov jiostxjyhriui'id part, to which
the .sella turcica and great wings belong, and an anterior or ijn'splwiwUl part, including the
body in front of the olivary eminence and the small wings, — a division which is found in
many animals persistent through life. The first osseous nuclei of the postsphenoid division
appear about the eighth week in the great wings {idlsphrnnidx), between the foramen
rotundum and foramen ovale, and spread thence outwards into the wing and downwards into
the external pterygoid plate. About the same time also two granules appear in the post-
ephenoid part of the body (JjasiKphenoid), placed side by side in the sella turcica ; these unite

' See J. Symington, Jouru. Anat,, xix, 281, and "Tiie Topographical Anatomy of tlie Child,"
1887, p. 46.

76

THE SKULL AS A WHOLE.

in the fourth month, and after their union two others appear {siihenotics')} from which are
formed the lingulas and adjoining parts of the carotid grooves. The internal pterygoid plates,
corresponding to the pteryguid, bones of animals, are ossified from distinct nuclei, which
appear in the fourth month ; they unite with the external pterygoid plates in the fifth month.
The great wings are united to the body in the first year.

In the presphenoid division the first pair of nuclei appears in the ninth week outside the
optic foramina, and extends by their growth into the small wings {o7-bitos2)he')iokls) : another
pair of granules appears on the inner sides of the foramina, and the presphenoid portion of the
body either results from the union of these, or is an independent growth. The presphenoid
ossifications are united to the body of the postsphenoid in the seventh or eighth month. At
birth the place of union is marked on the under aspect of the body by a wide notch, which
sometimes opens above by a small hole on the olivary eminence. The body of the presphenoid

Fig. 78. — Ossification of the sphenoid bone. (R. Quain.)

A, sphenoid bone at an early period, seen from above ; 1, 1', the greater wings ossified ; 2, 2', the
lesser wings, in which the ossification has encircled the optic foramen, and a small suture is distinguish-
able at its posterior and inner side ; 3, nuclei of basispheuoid.

B, copied from Meckel (Archiv. vol. i, tab. vi, fig. 23), and stated to be from a foetus of six
months; 2*, nuclei of presphenoid ; 5, separate lateral processes of the body (lingulge) : the other
indications are the same as in A.

C, back part of the bone shown in A ; 4, internal pterygoid plates still separate.

J), sphenoid at birth. The great wings are still separate. The presphenoid is now joined to the
basispheuoid, and the internal pterygoid plates (not seen in the figure) are united to the external.

is for some years broad and rounded inferiorly ; it begins to be hollowed by the sphenoidal
sinuses about the sixth year, and then becomes gradually narrower and more prominent, being
ultimately reduced to the thin sphenoidal septum.

The splunoidal spongy hones begin to ossify in the fifth month. At birth each consists of
a small sagittal lamina, resting against the presphenoid, and continued posteriorly into a
lateral projection, which is hollowed in front for the sphenoidal sinus, the latter having been
formed as a recess of the mucous membrane of the nose at the end of the third month. By
the third year the bone has entirely surrounded the sinus, forming an osseous capsule with
an anterior opening — the splienoidal foramen. About the fourth year the upper and inner
parts of this capsule begin to be absorbed, and the presphenoid then forms the wall of the
sinus, which in its farther extension excavates the body of the bone. At the outer and fore
part also absorption takes place, and the cavity there comes to be bounded by the ethmoid
and palate bones. The anterior projections of the sagittal plates meet in front of the pre-
sphenoid, and uniting with the vertical plate of the ethmoid form the rostrum. The spongy
bones are anchylosed first to the lateral mass of the ethmoid (about the fourth year), whence
they are often regarded as parts of that bone. They join the sphenoid from the ninth to the
twelfth year. (Toldt, " Die Entstehung und Ausbildung der Conchse und der Sinus sphenoidales
beim Menschen," Lotos, 1882.)

In the ethmoid bone ossification begins in the lateral masses during the fifth month, first
in the orbital plate, and then in the middle turbinate bone. In the first year a nucleus
appears in the vertical plate, and the cribriform plate is formed by ossification extending
from this internally and from the lateral masses externally. The three parts are anited in

^ J. B. Sutton, " On the Development and Morphology of the Human Sphenoid Bone," Proc. Zool.
Soc. Loud., 1885.

OSSIFICATION OF THE BONES OF THE HEAD,

77

the fifth or sixth year. The ethmoidal cells appear in the sixth month as depressions of the
mucous membrane, but bony walls are not developed until after birth.

The superior maxillary bone beo-jns to ossifj' immediately after the clavicle and the
lower jaw. The osseous ileposit takes place at several points, but the different parts speedily
fuse, and the precise number of centres is by no means certain. It is probable, however, that
the maxilla proper is developed in at least three pieces, a malar portion external to the infra-
orbital canal, an orbito-facial portion between the foregoing and the nasal fossa, and a
palatine portion including: the palate process and the adjoining part of the nasal wall. The
part of the bone which carries the incisor teeth, extending as far back as the incisor foramen,
has an independent origin, corresponding to the protia.rillary bone of the lower animals. In
the young subject always, and often in the adult, there is to be seen a fine iiici-ior p's-sitrt on
the under surface of the palate process, passing outwards from the anterior ijalatine fossa to
the alveolar border, internal to the canine socket ; and on the upper surface a similar line
may be seen, though less frequently, extending up some distance on the nasal surface of the
body : but no trace of the line of union exists on the facial surface, as is the case in the
lower animals. This is due to the development at the lower and fore part of the maxilla of
an outgrowth, termed the inciHor process, which forms the front wall of the incisor sockets ;

Fig. 79.— Different views of the superior maxillary bone of a fostls of four or five

MONTHS. (R. Quain.)

A, external surface ; a fissure, 1, is seen extending from the orbital surface into the infraorbital
canal.

B, internal surface ; the incisor fissure, 2, extends from the foramen upwards tlirough the hori-
zontal plate and some way into the nasal process.

C, the bone from below, showing the imperfect alveoli and the incisor fissure, 2', 1, which crosses
the palate plate to the septum between the second and third alveoli.

behind this process, between it and the palate process, is a deep groove in which the pre-
maxillary bone is formed, the latter being distinct up to the fifth month of fcetal life.
(Callender. Phil. Trans.. 1869 ; Th. KoUiker," Os intermaxillare des Menschen," 1882 ; Sutton,
Proc. Zool. Soc, 1884.)

The sockets of the teeth are formed by the do-wngrowth of an outer and an inner plate on
the sides of the dental groove, and subsequently the partitions appear, those on each side of
the canine tooth first. The antrum appears as a shallow depression on the inner surface of

Fig. 80. — The %'omer at the time of birth. (R. Quain.)

1 & 2, the two jjlates forming a groove for the reception of the se^jtal
cartilage.

the bone at about the fourth month : this gradually extends, separating the orbital and
palate portions of the bone, which at birth are still very close together. At its first ajjpear-
ance the antrum has a cartilaginous wall, which afterwards becomes absorbed. The infra-
orbital canal begins as a groove on the orbital surface, which is gradually closed by the
growing over of the outer margin ; but a fine suture remains indicating the line of meeting.

The palate bone is ossified from a single centre, which appears in the seventh or eighth
week at the angle between its horizontal and vertical parts.

The vomer is ossified from a pair of nuclei which arise in membrane at the lower and
back part of the cartilaginous nasal septum in the eiglith week. They soon unite below, but
growing forwards and upwards form the two laminte which embrace the septal cartilage.
These laminae gradually undergo increased union from behind forwards till the age of
puberty, thu.s forming a median plate, with only a groove remaining on its anterior and
superior margins.

The nasal and lachrymal bones are each ossified from a single centre a])pearing about the
eighth week. At the time of birth there is a layer of cartilage beneath the nasal bone, which

78 THE SKULL AS A WHOLE.

is continuous above with the ethmoidal cartilag^e, and below with the lateral cartilage of the
nose : this subsequently disappears.

The malar toone also commences to ossify about the eighth week. According to Rambaud
and Renault it is developed from three points which have united by the fourth month of
foetal life ; and to the persistent separation of one of these, the divided condition of the bone
referred to on p. 56 may be due.

The inferior turbinate bone is ossified in cartilage from a single centre, which only
appears in the fifth month.

The inferior maxillary bone is developed principally in the fibrous tissue investing
Meckel's cartilage (see development of the head in Vol. I.), but to a less extent the cartilage
itself participates in the ossification. At birth it consists of the lateral parts united at the
symphysis by fibrous tissue : the osseous union takes place in the first or second year. The
process of ossification commences very early, being preceded only by the clavicle, and proceeds
rapidly : it takes place from several centres, which are united by the fourth month. The
largest part of each half is formed from a deposit {dentarij) in the membrane on the outer
side of Meckel's cartilage ; and to this there is added a second smaller plate {splenlal) which
forms the inner wall of the tooth-sockets, terminatiug behind in the lingula. A small part of
the body by the side of the symphysis results from the direct ossification of the anterior end
of Meckel's cartilage ; and, posteriorly, the condyle and a portion of the ramus, including the

Fig. 81. — The inferior maxilla of a child at birth.
(E. Quain. )

a & b indicate the two portions separate at the
symphysis.

angle, are developed from another ossification in
cartilage. The last, however, is not connected with
Meckel's cartilage, which can be seen in a foetus of
the fifth or sixth month to be prolonged up to the
fissure of Glaser, where it becomes continuous with the slender process of the malleus, sur-
rounded by fibrous tissue which eventually forms the so-called internal lateral ligament of
the jaw. (Callender. Phil. Trans., 1869 ; Kolliker. " Entwickelungsgeschichte "' ; Toldt,
" Wachsthum des Unterkiefers." Prag, 1883 ; Sutton, Trans. Odont. Soc, 1883.)

At birth, the body of the jaw is shallow, the basal part is but little developed, and the
mental foramen is nearer the lower than the upper margin ; the ramus is very short and
oblique, the angle which it forms with the body being about 1J:U° ; the neck of the condyle
also is short and inclined backwards : and the coronoid process projects above the condyle.
During the succeeding years the body becomes deeper, thicker, and longer, the ramus and the
neck of the condyle lengthen, and the angle at which the ramus joins the body becomes less
obtuse, till in the adult it is nearly a right angle. In old age, consequent upon the loss of the
teeth and the absorption of the alveolar margin, the body becomes shallower, the mental
foramen opens at the upper border of the bone, and the angle is again increased.

The hyoid bone has five points of ossification — one for the body, and one for each of its
great and small cornua. The ossification begins in the great cornua and body in the last
month of foetal life, in the small cornua in the first year after birth. The great cornua and
body unite in middle life, the small cornua only exceptionally in advanced age. The stylo-
hyoid ligaments are occasionally ossified in some part of their extent.

GENERAL MORPHOLOGY OF THE BONES OP THE HEAD

The circumstances which contribute most to modify the form of the human skull and the
condition of its component bones, as compared with that of other animals, are — 1st, the
proportionally large size of the brain and the corresponding expansion of the cranial bones
which enclose it ; 2nd, the smaller development of the face as a whole, and especially of the
jaws, which brings the facial bones almost entirely under the fore part of the brain-case,
instead of in front of it, as occurs in all animals, with the partial exception of the anthropoid
apes ; and 3rd, the adaptation of the human skeleton to the erect posture, which, as regards
the head, is attended with the sudden bend of the basicranial axis at a considerable angle upon
the line of the erect vertebral column ; and along with this the great development of the
cranium in a backward direction, whereby the occipito-vertebral articulation comes to be
placed approximately in the centre of the antero-posterior length of the skull, so that the
head is nearly balanced on the upper extremity of the sprae. The downward openings of the
nostrils, the forward aspect of the orbits and eyes, the nearly vertical forehead and more or
less oval-shaped face, are accompaniments of these human peculiarities in the form of the
head, which, together with those already mentioned, strongly contrast with the smaller

GENERAL MORPHOLOGY OF THE BONES OF THE HEAD.

79

cranium and its strong- crests of bone, the largrer projecting face and jaws, and the other
characteristic features of the skull in most animals.

As reo-ards the condition of the individual bones, it is farther to be remarked that there is
o-enerallv in the human skull a more complete consolidation or bony union of the osseous
elements than in animals, so that the whole number of bones forming the cranium and face
is least in man. Thus, to mention only some of the most marked examples of this difference
among mammals : the frontal bone and the lower jaw frequently divided into two lateral
portions ; the premaxillary very generally a separate bone from the maxillary : the presphenoid
in many separate from the postphenoid ; the interparietal from the occipital ; and the
squamosal and styloid ossifications from the periotic. It is also worthy of observation that
the conditions now referred to as permanent in animals exist as transitory stages of develop-
ment in man.

Homolog-ies. — It is not possible here to enter at any length into the consideration of the
homoloL;ies of the bones of the human skull, but the diagrammatic representation of the bones
of the foetal head in fig. 82, and the following table will serve to indicate to .some extent the

Fig. Si'. — Diagrammatic view

OF THE BONES IN THE RIGHT
HALF OF A FffiTAL SKULL,
FROM THE INSIDE. (Allen

Thomson.)

In this figure the bones have
been slightly separated and dis-
placed so as to bring the whole
into one view : /, frontal ; ^w,
parietal ; so, supraoccipital ;
11, nasal ; I, lachrymal ; via,
malar ; os, orbitosphenoid ;
OS, alisphenoid ; sq, squa-
mosal ; Z1J, zygomatic ; ^«v,
periotic ; co. exoccipital ; d,
ethmoturbinal ; inx; maxilla ;
mt, maxilloturbinal ; pm, pre-
maxillary ; mc, mesethmoid ;
V, vomer ; ^^Z, palatal ; p(,
pterygoid ; jjs, presphenoid ;
bs, basisphenoid ; bo, basioc-
cipital ; c, bodies of 2nd, 3rd,
and 4th cervical vertebras ; c',
odontoid process ; x , anterior
arch of atlas ; .«, spinous pro-
cesses of 1st, 2nd, 3rd, and
4th cervical vertebraj ; cin,
neural canal ; ch, a line indi-
cating the position of the
notochord passing through the
vertebral bodies into the V)ase
of the cranium ; ti/, tympanic,
along with m!, i, and st, dis-
placed from its connection with

per ; ml, malleus ; c. 'ink, cartilage of Meckel ; mn, mandible
ch, ceratohyal ; th, tliyrohyal ; bh, basihyal ; t, thyroid cartilage

i, incus ; st, stapes ; sth, .stylohyal ;

morphological relations of the several bones to each other, and to those of other vertebrate
animals, and to explain the origin of the constituent elements of the skull. Additional
information as to the latter point will be found in the account of the development of the head
in the chapter on Embryology in Vol. I. ; and for a fuller explanation of the homologies of the
bones the reader is refeiTed to works on Comparative Anatomy.

LI.ST OF THE TYPICAL COMPONENT PARTS OF THE BONES OF THE HEAD
CLASSIFIED ACCORDING TO THEIR ORIGIN ' :—

1. BONES DEVELOPED IN THE PRIMITIVE CARTILAGINOUS CRANIUM.

Basioccipital ; Basilar process of the occipital bone.

Exoccipitals ; Condylar portions of the occipital bone.

Supraoccipital ; Lower division of the tabular part of the occipital bone.

' Tlie names first given, and printed in black type, are those received in comparative anatomy ;
those UKually emi^loycd in human anatomy follow, and are printed in common typo.

80 THE SKULL AS A WHOLE.

Periotics ; Greater parts of the petrous and mastoid portions of the temporal bones.
Basisphenoid ; Posterior part of the body of the sphenoid bone, including the sella
turcica.

Alisphenoids ; G-reat wings of the sphenoid with the external pterygoid plates.
Presphenoid ; Anterior part of the body of the sphenoid bone.
Orbitosphenoids ; Small wings of the sphenoid bone.

2. MEMBRANE-BONES COMPLETING THE CRANIAL WALL.

Interparietal ; Upper division of the tabular part of the occipital bone.

Parietals ; The parietal bones.

Prontals ; United in the single frontal .

Squamosals ; The squamous parts of the temporal bones with the zygoma.

3. BONES DEVELOPED IN THE CARTILAGINOUS NASAL CAPSULE.

Mesethmoid ; Vertical plate of the ethmoid bone, together with the cartilaginous part of
the nasal septum.

Ethmoturbinals ; The lateral masses of the ethmoid, including the upper and lower
turbinate bones.

Maxilloturbinals ; The inferior turbinate bones.

Sphenoidal turbinals ; The sphenoidal spongy bones.

4. MEMBRANE -BONES DEVELOPED AROUND THE NASAL CAPSULE AND FORMING
THE GREATER PART OP THE UPPER FACE.

Lachrymals ; The lachrymal bones.

Nasals ; The nasal bones.

Maxillae ; The superior maxillary bones, excepting the incisor part.

Premaxillse or interm.axill8e ; The incisor parts of the superior maxillary bones.

Jug-als or m.alars ; The malar bones.

Palatals ; The palate bones.

Pterygoids ; The internal pterygoid plates.

"Vomer ; The vomer.

5. BONES DEVELOPED IN THE CARTILAGINOUS VISCERAL ARCHES Or

THE HEAD.

Malleus, Incus, and Stapes ; The auditory ossicles or malleus, incus, and stapes.
Tympanohyals and Stylohyals ; The styloid processes of the temporal bones.
Epihyals ; The stylo-hyoid ligaments (occasionally ossified in man),
Ceratohyals ; The small comua of the hyoid bone.
Thyrohyals ; The great comua of the hyoid bone.
Basihyal ; The body of the hyoid bone.

6. MEMBRANE-BONES DEVELOPED IN CONNECTION WITH THE VISCERAL ARCHES

Mandible ; The inferior maxillary bone (a small part is developed in the cartilaginous
arch).

Tympanies; The tympanic plate, forming the auditory and vaginal processes (developed in
the periphery of the membrane closing the first visceral cleft).

The relations of the nerves at their passage out of the cranium to the osseous elements
are remarkably constant, and afford considerable assistance in determining their homologies.
Thus, the nerves of the principal sense-organs pass into their special capsules as follows, viz..
the olfactory between the mesethmoid and ethmoturbinal divisions of the ethmoid bone ; the
optic between the orbitosphenoid and the presphenoid ; and the auditory between the prootic
and opisthotic divisions of the periotic mass. Farther, the motor nerves of the orbital muscles
(third, fourth and sixth), together with the ophthalmic division of the trifacial (fifth), pass
through the sphenoidal fissure between the orbitosphenoid and alisphenoid, while the second
division of the trifacial has a special foramen in the alisphenoid which has been separated off
from the sphenoidal fissure by the growth of bone around the nerve. Similarly, the foramen
ovale for the third division of the trifacial has been cut off from the foramen lacerum between
the alisphenoid and periotic. The facial (seventh) nerve leaves the cranial cavity with the
auditory between the divisions of the periotic, and then traverses a canal (aqueduct of
Fallopius), the lower part of which is included between the outer surface of the periotic and

GENERAL MORPHOLOGY OF THE BONES OF THE HEAD. 81

the tympanic plate, while its Vidian branch occupies a canal surrounded by the basisphenoid,
alisphenoid and pterygoid elements of the sphenoid bone. The glosso-pharygeal (ninth)',
pneumo-g-astric (tenth) and spinal accessory (eleventh) nerves pass between the periotic and
exoccipital ; and the hypoglossal (twelfth) between the exoccipital and basioccipital. The
internal cai-otid artery, it may be added, enters the skull by the foramen lacerum, a space
between the basisphenoid, alisphenoid, and periotic. having previously traversed the carotid
canal formed by the downgrowth of the opisthotic ; and the jugular vein issues between
the periotic and exoccipital.

A general review of the construction of the skull shows that it may be regarded as consist-
ing mainly of three sets of parts, viz. — 1st, basal or central parts, comprising the basi-
occipital, basisphenoid, presphenoid, and mesethmoid, which form a series prolonged forwards
in the line of the vertebral axis, and constitute a cranio-facial axis ; 2nd, superior arches
three in number, enclosing the brain, and consisting of more or less expanded bones, viz., the
exoccipitals and supraoccipital together with the interparietal, the alisphenoids, squamosals and
parietals, the orbitosphenoids and f rentals ; and 3rd, inferior arches, surrounding the visceral
cavity as represented by the nose, mouth, and pharynx ; these include the pterygoids, palatals
and maxillae in a first arch, the mandible and the malleus of the internal ear in a second, the
cerato-, epi-, stylo- and tympanohyals in a third, while the thyrohyals are the rudiments of a
fourth, and the basihyal is interposed between the last two. To these succeed in the lowest
vertebrates the series of branchial arches, one, or perhaps two, of which may be in part
represented by the thyroid cartilage of the larynx. Together with the foregoing there are
associated other elements, viz. — 1st, the periotic enclosing the organ of hearing, and the
ethmo- and maxilloturbinals covering the organ of smell, which have been classed sepa-
rately as special sense-capsules ; and 2nd, tlie small bones of the face, malar, nasal,
and lachrymal, supplementary to the maxillary arch, and the vomer, extending the
cranio-facial axis.

There is thus a certain resemblance in the arrangement of the chief parts of the skull to
that of the trunk-skeleton, and this resemblance has led to the conception of what is called
the vertebrate theory of the skull, according to which the skull consists essentially of a
series of vertebrai, the dorsal or neural arches of which have undergone great expansion, so
as to predominate over the less developed ventral or visceral arches. Certain circumstances
in the growth of the skuU, especially the formation of a part at least of the cranio-facial axis
around a prolongation of the notochord, appear at fii-st sight to give support to this view ;
but the more complete knowledge of the mode of development of the skull which has been
obtained of late years tends to show that there is no such homodynamous correspondence
between the several bones of the skull and the vertebral segments of the trunk-skeleton. In
explanation of this statement the following points of difference between the two jnay be
specially referred to, viz. — 1, a large part of the cranio-facial axis is prechordal, being formed
beyond the cephalic extremity of the notochord, and therefore does not correspond to vertebral
bodies ; 2, the cartilage in which the bones of the cranio-facial axis and its lateral expansionj
are developed is not at any period segmented, as is the cartilage preceding the vertebras ; 3,
the segmentation which is to be recognized in the bones of the skull does not agree with the
segmentation which has been observed in the head of lower vertebrates at an early period of
embryonic life ; 4, the bones forming the dorsal and ventral arches of the heac: are in large
part developed in membrane, and are probably dermal in origin, whereas the arches of the
vertebrae are entirely of cartilaginous origin ; and 5, the cartilaginous visceral arches of the
head probably do not correspond to the costal arches of the vertebra, being formed in close
connection with the wall of the alimentary canal, while the ribs are developed in the body-
wall or Bomatopleure.

On the whole, it would appear, therefore, that the skeleton of the head and the skeleton
of the trunk agree in being formed in continuous tissue lying between and surrounding the
cerebro-spinal axis and the alimentary canal, and that the correspondence observed in their
general construction is due to this community of origin and relations. But the several bone»
are developed independently, and in a different manner in the head and trunk, giving rise in
the one case to the skull, in the other to the vertebral column ; and although the head as a
whole is undoubtedly derived in large part from a portion of the body that was primitively
segmented, there is no evidence to show that the appearance of the skull has been preceded
by a stage in which osseous or even cartilaginous vertebras are developed in connection with
these segments.' (Huxley, "Lectures on Comp. Anat.," 186i ; Gegenbaur, "Elements of
Comparative Anatomy," and Morph. Jahrb., xiii ; O, Hertwig, " Lehrb. der Entwicklungs-
geschichte.")

' The fecial conditions referred to above are fully explained in the section on Embryology in
Vol. I.

82

THE SKULL AS A WHOLE.

a?HE VARIOUS rORMS OF THE SKULL.

I. Differences according: to age. — In the earlier stages of its development the posterior
part of the cranium bears a very large proportion to the anterior part ; so much so, that in
the second month of festal life the line of the tentorium cerebelli is vertical to the basis
cranii, and divides the cranial cavity almost equally into two parts. The parietal region then
increases rapidly in volume, along with the greater development of the cerebral hemispheres ;
the frontal region next augments ; and again, in the latter part of foetal life, the occipital
region increases as the cerebrum extends backwards (Cleland). At the time of birth the
parietal region has reached its largest development in proportion to the occipital and frontal
regions. The greatest frontal breadth is then smaller in proportion to that between the
parietal eminences than afterwards. The base of the cranium is relatively small, and the
great wing of the sphenoid and the temporal squama do not extend so far upwards as subse-
quently is the case. The petrous, which is. however, comparatively large, is inclined more
forwards than in the adult. Other peculiarities, such as the existence of the fontanelles, the
prominence of the frontal and parietal eminences, and the absence of the mastoid processes,
have been referred to in describing the development of the several bones. The face at birth
scarcely reaches an eighth of the bulk of cranium, while in the adult it is at least a half
(Froriep). The skull grows rapidly during about the first seven years of life. By that time

Fig. 83. — Lateral view op the child's skull at
BIRTH. (Leishman.) -g

This figure shows the elongated form of the skull in
the infant, and the small proportion which the facial
bears to the cranial part, and also the lateral fontanelles
at the lower angles of the parietal bones. The lines indi-
cate the various diameters.

certain parts, including the circumference of the
occipital foramen, the body of the sphenoid, the
cribriform plate, and the petrous division of the
temporal, have attained their definitive size. The
other regions also increase but little until the
approach of puberty, when a second period of
active growth begins, affecting especially the face and the frontal portion of the cranium,
with which is associated the expansion of the frontal and other air-sinuses (Merkel). The
face becomes elongated in the progress of growth, partly by increased height of the nasal
fossas and adjacent air-sinuses, partly by the growth of the teeth and the enlargement of the
alveolar arches of the jaws. In old age the skull commonly becomes lighter and thinner, and
often a little smaller ; but in some cases it increases in thickness and weight owing to deposit
of bone on the interior of the brain-case without a corresponding degree of absorption
externally (Humphry). The proportion of the face to the cranium is also diminished by the
loss of the teeth and absorption of the alveolar portions of the jaws. In consequence of this
the upper jaw retreats, while in the lower jaw the same cause gives, especially when the mouth
is closed, a greater seeming prominence to the chin. (Froriep. " Characteristik des Kopfes
nach dem Entwickelungsgesetz desselben," 184.5 ; Buschke, " Schadel, Hirn und Seele," 1854 ;
Virchow, " Entwickelung des Schadelgrundes." 18.57 ; Humphry, "A Treatise on the Human
Skeleton," 1858, and " Old Age," 1889 ; Welcker, " Wachsthum und Ban des menschlichen
Schadels," 1862 ; Cleland, " On the Variations of the Human Skull," Phil. Trans., 1869 ; Merkel,
" Beitrag zur Kenntniss der postembryonalen Entwicklung des menschlichen Schadels," 1882.)

II. Sexual differences. — The female skull is, in general, smaller, lighter, and smoother
than that of the male ; the muscular Impressions are not so strongly marked, the mastoid
processes and the superciliary ridges are less prominent, and the frontal sinuses less developed.
The cranial capacity is less, on the average, by one-tenth, than that of the male in the same
race, and the frontal and occipital regions are less capacious in proportion to the parietal
(Huschke). The face is smaller in proportion to the cranium, the zygomatic arches slender,
and the jaws narrower and less prominent. The female skull resembles the young skull more
than that of the adult male ; but it must be admitted that it is often impossible to determine
the sex by the appearance or form of a skull.

III. Eace differences, their measurement and classification. Craniometry. — The most
important measurements and characters in comparing skulls of different races are the cranial
capacity, the circumference of the cranium, the relative length, breadth and height of the
cranium, the degree of projection of the jaws, and the form of the nasal skeleton and the
orbital opening.

THE VARIOUS FORMS OF THE SKULL.

83

The capacity of the cranium affords the most convenient indication of the development
of the brain.' It is ascertained bj- iilling- the cranial cavity with shot, and then measuring
the contained quantity in a properly graduated vessel, special precautions being taken to
ensure as neaiiy as possible an equal pressure in both operations. The capacity of the normal
human cranium varies from 1.000 to 1.800 cubic centimetres (about 60 to 110 cubic inches),
•with an average in all races of 1.400 cubic centimetres (85 cubic inches). Skulls with a
capacity of from l.:?r)0 to 1.450 cubic centimetres are placed in a middle group and termed
nie'tocTpfiijIir. those exceeding 1.450 cubic centimetres in capacity are mrr/ac/'jilui/ir. and those
below 1.350 cubic centimetres are micmccphalic (Flower). The following examples are of
males only : —

Cub. cpntim

Cub. inches.

Eskimo . . .

1500

91-5

European

1480

90-3

Chinese and Mongols.

1430

87-3

African Xegroes

] 350

82-4

Native Australians .

1300

79-3

Andaman Islandei's .

1280

78-1

Before proceeding to the consideration of the linear measurements it is necessary to refer
to certain definite points on the surface of the skull from which such measurements are

Fig. 84. — Side view of skull

OF X MALE AUSTRALIAN.

(After Flower.)

A, alveolar point ; S, sub-
nasal point ; N, nasion ; G],
glabella ; Op, ophryon ; Bg,
bregma ; Ob, obelion ; L,
lambda ; 0, occipital point ;
I, inion ; B, ba.sion ; Pt,
pterion ; St, stephanioii ; As,
a.sterion ; Gl O, length of
cranium ; B N, basinasal
length ; B A, basialveolar
length ; N S, nasal height.

taken, or which have a
particular importance as
presenting varieties of more
or less frefiuent occurrence,
and to which special names
have been g'iven not of ordi-
nary use in descriptive
anatomy. These are : —

Alveola)- ^w<'«^ (fig'. 84, A). — The centre of the anterior margin of the upper
alveolar arch.

Suhnaml or apinal j)oint (S). — The middle of the inferior border of the anterior nasal
aperture at the base of the nasal spine.

yaxiiiii or 7iu sal 2)0 hit, (X). — The middle of the naso-frontal suture.

Ophvium or tmpruorhltal point (Op). — The middle of the supraorbital line, which, drawn
across the narrowest })art of the forehead, separates the face from the cranium.

lircfinia (Bg-). — The point of junction of the coronal and sagittal sutures.

OhclUni (Ob). — The region situated between the two parietal foramina where the sagittal
suture is more simple than elsewhere, and where its closure generally commences.

Lambda (L) — The point of junction of the sagittal and lambdoid sutures.

Occipital point (0). — The point of the occiput in the median plane most removed from the
glabella.

* According to Manouvrier (Mem. do la Soc. dAntlirop. de Paris, 2 scr., t. iii, 1885), the weight
of the brain in grammes may be approximately ascertained by multiplying the cranial capacity in cubic
centimetres by 'S?. i5ut it i.s to be remarked that Manoiivrier's capacities were obtained b}- Brora's
method, which undoubtedly gives too high results. Welcker proposes (Aruli. f. Antlirop., xvi, .'51) a
sliding scale, ranging from 91 gr. of brain-weight to 100 ccm. of cranial capacity for skulls with a
capacity of 1200 ccm. to 95 gr. to 100 ccm. for skulls of lOOO ccm. capacity. Thus 1480 x -938 =:
1388 gr., which agrees closely with the average European brain-weight a.s ascertained by direct
obsfervati'jn.

0,1

length (

84 THE SKULL AS A WHOLE.

Inion (I). — The external occipital protuberance.

OjnstJiion.— The middle of the posterior margin of the foramen magnum.

Basiun (B).— The middle of the anterior margin of the foramen magnum.

Pteriori (Pt). — The region, near the anterior part of the temporal fossa, where the great
wing of the sphenoid, the squamous, the parietal and the frontal bones approach each other,
the exact disposition, however, vaiying in different individuals. In the most common
condition the parietal and great wing of the sphenoid meet and form a short horizontal
suture ; but it sometimes happens that these two bones are separated by the junction of the
frontal and squamous, giving rise to a vertical fronto-temporal suture, generally continuing the
line of the coronal suture. The latter form is especially frequent in some of the lower races of
mankind, and is the rule in the gorilla and chimpanzee. There is often a small Wormian bone
in this situation, the epijJtei'ic lone of Flower, and many cases of the occurrence of a fronto-
temporal suture are attributable to the union of this piece of bone with the squamous or frontal.

Stephanion (St). — The point where the corona'' suture crosses the temporal line.

Asterion (As). — The point where the lambdoid, parieto-mastoid and occipito-mastoid
sutures meet. When a separate interparietal bone is present the suture dividing it from the
supraoccipital runs transversely from asterion to asterion, which will in that case be the
meeting point of four sutures.

Auricular 2}oint. — The centre of the orifice of the external auditory meatus.

The circumference of the cranium (horizontal) is taken in a plane passing anteriorly
through the ophryon,i ^nd posteriorly through the occipital point (fig. 84, Op 0). This may
exceed to a slight degree 5.50 millimetres (21-7 inches) or it may be as low as 4,50 mm.
(17'7 inches). The average in the adult European male is 525 mm., in the female 500 mm.
For comparison of the relative development of the anterior and posterior portions of the
cranium, the preauricular part of the circumference is divided from the postauricular part by
a line on each side passing from the auricular point to the bregma (auriculo-lregmatic line).

The length of the cranium (maximum) is measured from the most prominent point of the
glabella to the occipital point (fig. 84, Gl O), and this is made the standard = 100. The
breadth (maximum) is the greatest transverse diameter of the cranium above the supramastoid
ridges, measui-ed perpendicularly to the median plane. The proportion of the latter to the
100 X breadth \ ^^ ^^^ ^^^^^ ^y breadth or the cephalic index. Skulls with a
length /

breadth-index above 80 are hrachy cephalic, txova. 75 to 80 mesaticephalic, and below 75 dulicho-
cejjhalic.

The heig-ht of the cranium, is measured from the basion to the bregma, and the proportion
of this to the length, calculated in the same way, is the index of height. It is subject to less
variation than the breadth-index ; in some cases, especially in dolichocephalic skulls, it
exceeds, but more frequently it falls below that index.

Mongolians of Siberia and Central Asia
Andaman Islanders ....
Chinese ......

English

Native Australian ....
Fiji Islanders .....

For a more accurate determination of the form of the cranium other measui-ements are
taken, such as the transverse circumference, passing through the auricular point on each side
and the bregma above ; the longitudinal arc from the nasion to the opisthion, with its
subdivisions into frontal, parietal and occipital arcs ; transverse arcs from the posterior root
of the zygoma immediately above the auricular point of the one side to the other, across the
most prominent parts of the frontal, parietal, and occipital bones respectively. The antero-
posterior curve of the roof may also be indicated by a series of radii from the basion to the
centre of the frontal bone, the bregma, the vertex and the lambda. Other features again are
not capable of being expressed in terms of direct measurement, and must be described in each
case ; for example, the form of the transverse arch of the cranium, which in the best shaped
skulls is full and rounded, while in some races, notably in the Australian, the line of the
sagittal suture is elevated, and the surface on each side flattened or even somewhat depressed,
making the calvaria roof -shaped ; and this condition, combined with great prominence of the
parietal eminences or of the temporal lines, gives the skull, when viewed from behind, a
markedly pentagonal figure. The degree of complication and fusion of the sutm-es, the
amount of projection of the glabella and of the inion, and other variable points, may be stated
according to tables furnished by Broca in the work referred to below.

* Some anthropologists measure the circumference over the glabella (Turner, Schmidt).
' In these examples, which are taken from the Catalogue of the Museum of the Royal College of
Surgeons, the indices are calculated from the ophryo-occipital length.

Breadth-

Height-

inilex.

iudi'X.'

88

73

82

77

79

75

76

71

71

71

66

74

THE VARIOUS FORMS OF THE SKULL. 85

The situation and dii-ection of the foramen magnum differ greatly, as was pointed out by
Daubenton. in man and the lower animals, in connection with the altered position of the axis
of the head in relation to that of the vertebral column. In man the foramen is placed in or
near Ihe centre of the base of the skull, and its plane looks mainly downwards ; in quadrupeds
iz is placed on the posterior surface of the skull and looks backwards ; while in the anthropoid
npes it is intermediate in position and direction. But even in human skulls similar differences
•■iccur. though much less in degree. In the European the plane of the foramen is inclined
'ipwards anteriorly, in the Australian and Negro it is horizontal or even inclined slightly
upwards posteriorly. The degree of inclination requires for its determination a special
" occipital goniometer " designed by Broca.

In the skeleton of the face the most striking differences are met with in the size of the
jaws and the extent to which they project forwards. The human skull, in comparison with
shat of the lower animals, is especially distinguished by the great expansion of its cranial
portion and the relatively small development of the face, the latter being extended vertically
instead of horizontally, and thus brought downwards under the fore part of the cranium. A
marked prominence of the jaws constitutes, therefore, an approach to the animal type of
skull, and is to be regarded as a character of inferiority, particularly when it is accompanied,
as is often the case, by a low and receding forehead. The degree of projection of the jaws
beyond the cranium is most conveniently expressed by the gnathic or alveolar i?ide.v of Flower,
which is obtained by comparing the basialveolar length (fig. 84, BA) with the basinasal length
(BX) = 100; skulls with a gnathic index below 98 are ortliognatlious, from 98 to 103
viesognathous, and above 103 lyrognathous.

Gnathic Index.
English 'JG

Chinese .

Eskimo

Fiji Islanders

Native Australian

99
101
103
104

In the form of the nasal skeleton and the anterior nasal aperture variations are to be
recognised corresponding to the external conformation of the nose. Of these, the height and
width are capable of exact measurement, and the relation between the two, expressed by the
nasal index, becomes a character of considerable importance. The height is measured fi'om
the nasion to the subnasal point (fig. 84, NS), the width is the greatest transverse diameter
of the anterior nasal aperture, and the calculated proportion of this to the height = 100, is
the index. With a nasal index below 48 a skull is lejitorhine, from 48 to 53 mesorhine, above
5i platyrhine.

Nasal Index.

Eskimo ..... 44

English 46

Chinese ..... 50

Native Australian . . . 57

The form of the orbit also varies, but is a less significant character than that of the nose.
The orbital index is the ratio of the vertical height of the base of the orbit to the transverse
width = 100 ; if above 89 it is 7uegasente, between 89 and 84 viesoseme, and beloiv 84
microscine.

Orbital Index.
Andaman Islanders ... 91

Chinese
English .
Native Australian
Guanches of Teneriffe

90

88
81
80

For an account of the variations in the form of the palate and of the mandible, as well as
of the means of estimating the relative projection of the malar and nasal bones, and several
other measurements of the face skeleton, reference must be made to the special treatises.

(For more detailed information on the foregoing subject consult Broca, " Instructions
craniologiques et craniometriques," 1875 ; Flower, " Cat. of Museum of Roy. Coll. Surg, of Eng.,"
part i., 1879 ; de Quatrefages and Hamy, "Crania Ethnica," 1873-81 ; Topinard, "Elements
d' anthropologic generale ; " Turner, " Challenger " Reports, Zoology, x ; and Schmidt,
" Anthropologische Methoden," 1888. References to earlier writings of importance are given
in the last edition of this work.)

IV. Irregrularities of form. — The most frequent irregularity in the form of the skull is
•want of symmetry. This sometimes occurs in a marked degree, and there is probably )i() skull
perfectly pymmetrical. The condition which has been observed to co-exist most frcMjuently
with iri'egular forma of skull is premature synostosis or obliteration of certain of the sutures.

86 THE BONES OF THE UPPER LIMB.

The cranial bones increase in size principally at their margins ; and when a suture is
prematurely obliterated the growth of the skuU in the direction at right angles to the line of
suture may be supposed to be checked, and increased growth in other dii-ections may take
place to supply the defect. Thus, the condition known as scajjhoeejyhali) is found associated
with absence of the sagittal suture, where, the transverse growth being prevented, a great
increase takes place in the vertical, and especially the longitudinal directions, giving the vault
of the skull a boat-like form. Similarly, acrocephaly is related to obliteration of the coronal
suture, the compensatory growth taking place mainly upwards. Oblique deformity, or
plagioeejjhaly, also is met with in connection with premature fusion of one half of the coronal
or lambdoid suture ; but independently of this a precisely similar deformity may be induced by
rickets, wry-neck, or external pressure. (See Virchow, " Gesammelte Abhandlungen," IS.oG;
Lucae, " Zur Architectur des Menschenschadels," 1857 ; W. Turner in Nat. Hist. Rev., ISGi ;
J. Barnard Davis, "On SjTiostotic Crania," 186.5; Topinard. oj). cit.) Another series oi
irregular forms of skull is that produced by pressui-e artificially applied in early life, and is
best exemplified from among- those American tribes who compress the heads of their children
by means of an apparatus of boards and bandages : it is also illustrated in a slighter degree by
individual instances in which undue pressui-e has been employed unintentionally. (G-osse.
" Essai sm- les Deformations artificielles du Crane," 18.5.5 ; V. Lenhossek, " Die klinstlichen
Schadelverbildungen," &c., 1881.) Posthumous distortions likewise occur in long-buried
skulls, subjected to the combined influence of pressure and moisture. (Wilson, '• Prehistoric
Annals of Scotland.")

IV.— THE BOISTES OF THE UPPER LIMB.

The upper limb consists of the shoulder, the arm, hracMum, the forearm, ajiH-
Irachium, and the hand, mamis. The bones of the shoulder are the clavicle and
scapula, which together form the pectoral arch or shoulder-girdle ; in the arm is the
humerus ; in the forearm are the radius and ulna ; and in the hand three groups of
bones, viz., the carpus, metacarpus, and phalanges.

a?HE CLAVICLE.

The clavicle or collar-bone extends outwards and backwards, from the summit of
the sternum to the acromion process of the scapula, and connects the upper limb
with the trunk. It is curved like an italic/: the internal curve has its convexity

CONOID TUB.-

Fig. 85. — Eight clavicle, froji above. (Drawn by T. W. P. Lawrence.) |

directed forwards, and extends over two-thirds of the length of the t)one ; the
outer curve is concave forwards, corresponding to the hollow between the chest and
shoulder.

The clavicle is broad towards its scapular end, being compressed from above
downwards, but in the extent of its inner curve it is more or less prismatic or
cylindrical. In its description, four surfaces may be distinguished, together with the
two extremities.

The siqwrior surface is broadest in its outer part ; it is principally subcutaneous and
smooth, but near the inner extremity Dresents a slight roughness, marking the clavi-

THE CLAVICLE.

57

cular attachment of the sterno-cleido-mastoid muscle. The anterior surface opposite
the outer curve is reduced to a mere rough border, from which the deltoid muscle
takes origin ; but in the inner half of its extent it is broadened out into an uneven
space, more or less distinctly separated from the inferior surface, and giving attach-
ment to the pectoral is major muscle. ThQi^osterior surface is broadest at the inner
extremity, and smooth in the whole extent of the internal curvature ; but towards
its outer extremity it forms a thick border which gives attachment to the trapezius
muscle. x\.bout the middle of this surface is the aperture of a small canal for the
medullary artery, directed outwards. On the inferior surface, at the sternal end is a
rough impression for the attachment of the rhomboid ligament, by which the clavicle
is bound down to the first rib ; more externally is a groove, extending somewhat

Fig. 86. — Right clavicle, from below. (Drawn by T. W. P. Lawrence.) |

beyond the middle third of the bone, in which the subclavius muscle is inserted ;
behind this, projecting on the posterior border at the junction of the middle and
outer thirds, is a w^ell-marked eminence, the conoid tuhercle, to which the conoid
division of the coraco-clavicular ligament is attached, and from which the rough,
generally raised, trapezoid line, for the trapezoid part of the same ligameut, is directed
outwards and forwards towards the end of the bone.

The sternal end is the thickest part of the clavicle. It presents a somewhat
triangular concavo-convex surface, with its most prominent angle directed down-
wards and backwards. The scapular end is broad and flat, and articulates by a small
oval surface with the acromion.

The clavicle is subcutaneous to a greater or less extent in its whole length ; the
most prominent part is about the centre, corresponding to the intermuscular intervals,
above between the sterno-mastoid and trapezius, and below between the pectoralis
major and deltoid {supra- dind infraclavicular fossce). The outer extremity is a little
higher than the upper surface of the acromion against which it fits, and forms a
prominence on the upper part of the shoulder.

The interior of the clavicle contains coarse cancellated tissue in its whole extent, the
principal lamellas being' directed lonjritudinally. The shell of compact tissue is for the most
part very thick and dense, but it thins out gradually at the two emls of the bone.

Varieties. — At the inner part of the deltoid impression there is sometimes a flattened
projection known as the (Idto'id tuhcrdc. A small foramen for one of the supraclavicular
nerves is occasionally found at the fore part of the upper surface of the bone about the
middle.

THE SCAPULA.

The scapula is placed upon the upper and back part of the thorax, and forms
the posterior part of the shoulder-girdle. It is not attached directly to the trunk,
but is articulated with the outer end of the clavicle, and from it is suspended the
humerus in the shoulder-joint.

88

THE BONES OF THE UPPER LIMB.

It consists of a triangular blade or hody, supporting two large processes. The
surfaces of the body are anterior and posterior ; the borders superior, internal or
vertebral, and external or axillary ; the angles superior, inferior, and external ; the
last being the thickest part of the bone, and bearing the large articular surface, is
distinguished as the head, which is supported upon a neck. The processes are an
anterior, coracoid process, and a posterior, the spine, which is produced into the
icroniion.

TERES MAJOR

Fig. 87. — Dorsal view of right scapula. (Drawn by T. "W. P. Lawrence.) |

The anterior surface or venter, looking also considerably inwards, presents a
concavity, the subscapular fossa, occupied by the subscapularis muscle, and marked
by threa or four oblique j)rominent lines, converging upwards and outwards, which
give attachment to the tendinous intersections of that muscle. Separated from this
concavity, are two smaller fiat surfaces, one in iront of the superior angle and
the other at the inferior angle ; and these, together with the line running close to
the vertebral border and uniting them, give attachment to the serratus magnus
muscle.

The posterior surface or dorsum is divided by the spine into two unequal parts,
the upper of which is the supraspinous fossa, and the lower, the infraspinous fossa.
The supraspinous fossa is occupied by the supraspinatus muscle. The infraspinous

THE SCAPULA.

59

fossa, much the larger, presents in the middle a convexity corresponding to the
concantj of the venter, and outside this a concavity bounded by the prominent
axillaiT border. It is marked near the inner border by short lines, corresponding to
tendinous septa of the infraspinatus muscle, and is occupied l)y that muscle in the
greater part of its extent. Adjacent to the axillary border, in its middle third, is
a narrow area giving attachment to the teres minor muscle ; and below this, extend-
ing over the inferior angle, is a raised oval surft^ce, from which the teres major arises.

CLAVICULAR FACET
COHACOID

SUP. ANCLE

Fig. 88. — Right scapula, from before. (Drawn by T. W. P. Lawrence.)

These spaces arc separated from each other, and from that of the infraspinatus
muscle, bylines Avhich give attachment to aponeurotic se})ta.

The spine of the scapula is a massive triangular plate of bone projecting back-
wards and upwards from the dorsum. Beginning internally near the upper fourth
of the vertebral border, it extends outwards and a little upwards to the middle of
the neck of the scapula ; and becoming gradually elevated towards its outer extremity,
it turns forwards and is contirmed into the acromion process. The upper and lower
surfaces, smooth and conca\'e, form })art respectively of the supra- and infraspinous
fos-sae. It has two unattaciied borders, the more prominent of which is sub-
cutaneous, and arises from the vertebral border of the bone by a smooth, fiat,
triangular surface, over which the tendon of the inferior part of the trapezius

90 THE BONES OF THE UPPER LIMB.

muscle glides, as it passes to be inserted into a rough thickening beyond. In the
rest of its extent this border is rough, broad, and serpentine, giving attachment by
its superior margin to the trapezius, and by its inferior to the deltoid muscle. The
external border, short, smooth, and concave, arises near the neck of the scapula, and
is continuous with the under surface of the acromion, enclosing the great scapular
notch between it and the neck of the bone.

ThQ acromion process, projecting outwards and forwards from the extremity of the
spine over the glenoid cavity, forms the summit of the shoulder. It is an expanded
process, compressed from above downwards. Its superior surface, rough and
subcutaneous, is continuous with the prominent border of the spine ; while the
inferior surface, smooth and concave, is continuous with the superior surface and
external border of the spine. On its internal border anteriorly is a narrow oval sur-
face for articulation with the clavicle. Its outer border gives origin to the acromial
portion of the deltoid, and is marked by three or four tubercles from which tendinous
processes of this part of the muscle spring : posteriorly it terminates in the pro-
minent acromial angle, which overhangs the hinder margin of the glenoid cavity.
The apex of the acromion projects beyond the end of the clavicle, and gives attach-
ment to the coraco-acromial ligament.

The head bears the articular surface for the humerus, known as t\\Q glenoid cavity.
This is a slightly concave surface, looking outwards, forwards, and slightly upwards.
It is pyriform in shape, with the narrow end uppermost, and gently incurved in
front. Its rim is flattened, and in the recent state is covered by a fibrous bard, the
glenoid ligament, which deepens its concavity; at its upper extremity is a small mark
indicating the attachment of the long head of the biceps muscle.

The necTc, supporting the head, is most distinct behind, where it forms with the
spine the great scapular or acromio-scapular notch, leading from the supraspinous to
the infraspinous fossa ; its position is also marked above by the notch in the upper
border of the bone.

The cor acoid process, thick, strong, and hook-like, rises for a short distance almost
vertically from the upper border of the head, and then bending at a right angle, is
directed forwards and slightly outwards. Its superior surface, towards the base, is
rough and uneven, giving origin to the coraco-clavicular ligament ; on its outer
border is attached the coraco-acromial ligament, at its extremity the coraco-brachialis
muscle and short head of the biceps, and on the inner edge the pectoralis minor.

The superior lorder of the scapula is the shortest ; it extends from the superior
angle outwards and downwards to the coracoid process, at the base of which it presents
a rounded suprascapular or coraco-scapular notch, which is converted into a foramen
by a ligament, or occasionally by a spiculum of bone, and is traversed by the supra-
scapular nerve. The axillary border is the thickest ; at the upper end, below the
glenoid cavity, it presents a strong rough mark, above an inch long, to which the
long head of the triceps muscle is attached ; and below this there is usually a slight
groove, where the dorsal branch of the subscapular artery passes backwards ; on the
ventral aspect of this edge in the greater part of its length is a marked groove in which.
a considerable part of the subscapularis muscle arises. The vertebral border, called
also the base, is the longest of the three, and is divisible into three parts, viz., a short
one opposite the triangular surface of origin of the prominent border of the spine,
and the portions above and below that space, both of which incline outwards as they
recede from the spine. The upper part gives attachment to the levator anguli
scapulse muscle, the middle to the rhomboideus minor, and the lower to the rhom-
boideus major muscle.

The subcutaneous parts of the scapula are the free border of the spine in nearly
the whole of its length, the upper surface of the acromion, and a small part of the
vertebral border in its lower half ; the superior and axillary borders are entirely

THE HUMERUS.

91

concealed by the muscles. The coracoid process projects in front Ijcyond the clavicle,
and can be readily felt inside the head of the humerus, but can be seen only in thin
persons. AVith the arm hanging by the side, the scapula covers the ribs from the
second to the seventh inclusive, sometimes the eighth ; and the root of the spine and
the lower edge of the glenoid cavity are on a level with the interval between the
third and fourth dorsal spines. It must, however, be remembered that the bone
changes its position with every movement of the arm.

The bodj- of the scapula is in great part thin and translucent, and at these spots contain?
no cancellated tissue. The head, the coracoid and acromion processes, the prominent border
of the spine, and the thick rib along the axillary border, derive their greater thickness and
strength from increased thickness of the compact bony substance in some parts, and from
cancellated tissue in others. Vascular foramina piei-ce the upper and lower surfaces of the
spine, and others are to be found on the anterior surface of the t)one, near the neck.

The morphological axis of the scapula corresponds to the line of attachment of the spine.
extending from the glenoid cavity to the vertebral border of the bone. From this axis three
lamince radiate, the jm-scapida, mc-w.scaj)ula. and ])ot;t.<icapvIa of
Parker, giving rise to the three scapular fossas. The supraspinous
angle (between the prescapula and mesoscapula) measures about
100° ; the infraspinous and subscapular angles are each about 130°.'
The scapula of man is remarkable for the great development of the
postscapula. making the vertebral border very long and the inferior
angle prominent. This is an adaptation to the freedom of move-
ment possessed by the upper limb. The surface for attachment of
the rotator muscles of the humerus is thus increased, and greater
leverage is given to the lower part of the serratus magnus muscle,
which rotates the scapula ujjwards. The relative length and
breadth of the scapula are expressed by the acajnilar Index =

100 X breadth

i -r . The index is higher in the infant than in the

length "^

adult, and in Xegroes than in Europeans. (Broca, Bull. Soc.

Anthrop. Paris, 1S78 ; Flower and Garson, Joum. Anat., xiv ;

Turner, " Challenger" Reports, Zoology, xvi ; Dwight, '■ The Range

of Variation of the Human Shoulder-Blade.'' Amer. Nat., 1887.)

THE HUMERUS.

The hnmerus or arm-bone extends from the shoulder
to the elbow, where it articulates with both bones of the
forearm. It is divisible into the superior extremity, including
the head, iierJc, and great and small tuberosities ; the s/iaft;
and the inferior extremity, including the external and internal
condyles, and the inferior articular surface. In general form
it is subcylindrical and slightly twisted.

The superior extremity is the thickest part of the
bone. The head is a large hemispherical articular elevation,
directed inwards, upwards, and backwards. The neclc, as
described by anatomists, is the short portion of bone which
supports the head ; inferiorly, it passes into the shaft ;

superiorly, it is a mere groove between the head and the great tuberosity.
The great tuberosity is a thick projection, continued upwards from the external
part of the shaft, and reaching nearly to the level of the upper margin of the
head; it is surmounted ])y three flat surfaces, the uppermost of which gives
attachment to the supraspinatus muscle, the lowest to the teres minor, and the
intermediate one to the infraspinatus muscle. Separated from the great tuberosity
by the commencement of the bicipital groove is the small tuberosity, oval and
prominent ; it looks forwards and gi ves attachment to the subscapularis muscle.

POSTSCAPULft

Fig. 89. — Vertical sec-
tion OF THE SCAPULA,
PASSING THKOlGH THE
MIDDLE OF THE THREE
FOSS.«. (Gr. D. T.) i

* See Ward's " Outlines of Human Osteology."

THE BONES OF THE UPPER LIMB.

LATISS, DORSf

-TERES MAJOR

SMALL
3ER0S1TY
(sUBSCAPULARIs)

TUBEIROSITY

IHACHrALIS
ANTICUS

Fig. 90. —Right humerus, from before.
1 Drawn by T. W. P. LaM-rence.) |

Fig. 91. — Right humerus, from behind.
(Drawn by T. W. P. Lawrence. } |

THE HUMERUS.

m

The shaft or body, thick and cyHndrical above, becomes expanded transversely
and somewhat three-sided below. It is divided into anterior and posterior faces by
lateral lines, shghtly marked in the upper part, but more prominent in the lower,
where thev pass into the supracondylar ridges. Superiorly, on its anterior aspect
is the bicipital groove, so named from lodging the long tendon of the biceps muscle ,
this groove, commencing between the tuberosities, descends with an inclination
inwards, and is bounded by two rough margins, the external and more prominent
of which, jjertoml ridge, gives attachment to the pectoralis major muscle, the internav.

to the latissimus dorsi and teres major. To-
wards the middle of the shaft, on the inne.
lateral line, is a rough linear mark where the
coraco-brachialis muscle is inserted, and a little
lower down is the foramen by which the chief
medullary artery enters the bone, directed down-
wards. On the external part of the shaft, near
its middle, in a line anteriorly with the pectoral
ridge, is a large, elevated, and rough surface, of
a triangular shape, the deltoid eminence, for the
insertion of the muscle of the same name. Below
this, the ridge is continued into a smooth
elevation which, descending on the front of
the shaft to the inferior extremity, separates an

EXT,
RAO.

/

CAHP.
LONC.

/

.orvi.iiON

TENDON

f^

Sk

ii

-yl CAPITCLLUM

\

EXT. LAT. LICT.

NCONEU

S

ANCONEUS

Fig. 92. — Lower two-fifths of the right

HUMERUS, FROM THE OUTER SIDE. (Drawn

bvT. \V. p. Lawrence.) |

Fig. 93. — Lower EXTREMITY OF the right humerus
FROM BELoW. (Drawn by T. W. P. Lawrence.) |

external from an internal surface : while at the sides these are separated from the
flat posterior surface by the siqrracondglar ridges, which descend, the external more
prominent than the internal, to the condyle on each side. About the middle of the
shaft externally, a broad depression, the spiral groove, winds downwards and
forwards, limited above by the deltoid eminence, and below by "the external
supracondylar ridge: the hollow is for the most part occupied by a process of the
brachialis anticus muscle, but posteriorly, where there is often to be recognized a
second smaller groove, the musculo-spiral nerve and superior profunda vessels rest
against the bone. At the upper part of the groove there is generally a second
foramen for a branch of the superior profunda artery.

The external and internal surfaces below the deltoid eminence are occupied by the origin of
the brachialis anticus muscle. Posteriorly, the outer head of the triceps arises from the surface
above the spiral ^-roove. the inner head from the surface internal to and lielow the groove.
The external supracondylar ridjre drives origin in its upper two-thirds to the supinator longus,
in its lower third to tlie extensor carpi radialis longior. The external and internal inter-
muscular septa of the arm are also attached to the corresponding supracondylar ridges.

The inferior extremity is much enlarged laterally, flattened from before
backward.s, and curved slightly forwards. Projecting on either side are the external

94 THE BONES OF THE UPPER LIMB.

and internal condyles (the epicondyle and epitrochlea of Chaussier). The internal
condyle is the more prominent, and is slightly inclined backwards, forming
posteriorly a shallow groove in which the ulnar nerve lies : its extremity is marked
anteriorly by an impression to which the common tendon of the superficial
pronato-flexor muscles of the forearm is attached. On the external condyle are seen,

1, a mark for the common tendon of some of the muscles of the back of the forearm ;

2, below and internal to this, a smaller impression for the anconeus ; and 3, between
the foregoing and the margin of the radial articular surface, a pit in which the
external lateral ligament of the elbow-joint is attached. The inferior articular
surface is divided into two parts. The external part, articulating with the radius,
consists of a rounded eminence directed forwards, called the capifellum, and a
groove internal to it ; it does not extend to the posterior surface. The internal part,
the trochlea, articulates with the ulna, and extends completely round from the
anterior to the posterior surface of the bone; it is grooved in the middle hke the
surface of a pulley, and is somewhat broader behind than in front ; anteriorly, its
margins are inclined downwards and inwards ; posteriorly, upwards and outwards, so
that, seen from behind, it occupies the middle part of the bone. In front, the internal
margin of the trochlea is the more prominent, and forms a convexity parallel to the
groove ; behind, the external margin is slightly more prominent. Above the
trochlea posteriorly is a large and deep pit, the olecranon fossa, which receives the
olecranon process of the ulna in extension of the forearm ; and above it anteriorly,
separated from the olecranon fossa only by a thin lamina of bone, is the much smalltr
coronoid fossa, which receives the coronoid process in flexion. Above the capitellum
is a shallow depression — the radial fossa, into which the head of the radius is
pressed in complete flexion.

The humerus, in its natural position with the arm hanging by the side, has a
slight inclination from above downwards and inwards, and is also in a condition of
what may be termed strong internal rotation, i.e., the so-called anterior surface looks
very much inwards, and the internal condyle is directed more backwards than
inwards. The bone is almost completely covered by muscles ; the upper extremity
is thickly covered by the deltoid, which it pushes up, and thus gives roundness to
the shoulder : the shaft is entirely surrounded : both condyles are subcutaneous, the
internal being prominent, while the appearance of the external varies as the forearm
is moved. When the elbow is bent the capitellum projects under its muscular
covering, and forms the rounded prominence outside the point of the elbow.

The average length of the humerus in the adult male is about 13 inches, in the female 12
inches. It is nearly one-fifth of the stature of the individual, and somewhat more than twice
8,3 long as the clavicle.^

The major axes of the upper and lower extremities of the humerus do not lie in the same
plane, but cross one another at an angle, known as the angle of torsion, which varies greatly
in difPerent individuals, but averages about 20° in Europeans, and 35° in Negroes. The axis
of the upper end forms a smaller angle anteriorly with the sagittal plane than that of the
lower end. In quadrupeds the torsion is usually about 90°. (Broca, Rev. d'Anthrop., 1881.)

Varieties. — A small hook-like process, with its point directed downwards, is not un-
frequently found in front of the internal condylar ridge, the supracondylar process. From its

^ On the length and proportions of the long bones in different races of men may be consulted
Humphry, "A treatise on the human skeleton"; Topinard, " Elements d'anthropologie g^nerale ""J
Turner, *' Challenger " Keports, Zoology, xvi ; Kollet, '"'Mensuration des os longs des membres," 1889,

It may here be remarked also that the limb-bones of the two sides are seldom of equal length. In most
cases the bones of the upper limb (humerus + radius) are longer on the right side, the difference being
commonly about one-third of an inch, and rising occasionally to three-quarters of an inch. The
increased development is probably associated with the greater use of the right hand. In the lower limbs
the differences are not so marked, and the excess appears to be more frequently on the left side. These
differences do not exist at birth. (Garson, Journ, Anat., xiii, 502; Rollet, op. cit. ; Gaupp, " Maass-
und Gewichts- Differenzen zwischen den Knochen der rechten und linken Extremitaten," Diss.,
Breslau, 1889.)

THE ULNA. 95

extremity, a fibrous band, grivingr orijrin to the pronator radii teres muscle, descends to the
internal condyle, and through the arch thus formed passes the median nerve, accompanied
frequently by the brachial artery, or by a large branch rising from it. This process represents
a portion of the bone enclosing a foramen in many animals. (Struthers, Edin. Med. Journ.,
1848; Gruber, '• Can. supracond. humeri," Mem. Acad. Imp. St. Petersburg, 1859.) The thin
plate between the olecranon and coronoid foss« is sometimes perforated, forming the supi-a-
trochlear or intercimdijlar foramen,

THE XJLNA.

The ulna is the internal of the two bones of the forearm, and is longer than the
radius by the extent of the olecranon process. It is inclined downwards and out-
ivards from the humerus in such a dii-ection that a straight line passing from the
great tuberosity of the humerus downwards through the capitellum would touch the
lower end of the ulna.

The ulna articulates with the humerus and the radius : in the natural skeleton it
is not in contact with the carpal bones, being excluded fi'om the wrist-joint by an
interarticular fibro-cartilage.

The superior extremity is much the larger, and articulates with the humerus
by means of the great sigmoid cavity, which looks forwards and upwards, and is
bounded in its posterior and upper part by the olecranon, a thick process continued
upwards from the shaft, and in its lower part by the coronoid process projecting
forwards. The great sigmoid cavity is concave from above downwards, and traversed
by a longitudinal ridge. The part external to this ridge is broad and convex above,
while the part internal to the ridge is concave and broader below : a slight
constriction, and sometimes a groove of division, occurs across the middle of the
cavity. Continuous with the great is the small sigmoid cavity, a small articular
surface on the outer side of the base of the coronoid process, concave from before
backwards, for the reception of the head of the radius. Superiorly, the olecranon is
broad and uneven, terminating in front in an acute process or healc, which overhangs
the great sigmoid cavity, and which in exteusion of the elbow passes into the
olecranon fossa of the humerus, and behind in a rectangular prominence or
tuberosity, which forms the point of the elbow, and gives attachment to the triceps
extensor muscle. The posterior surface of the olecranon is subcutaneous and
continuous with the posterior margin of the shaft of the ulna. The extremity of
the coronoid process is sharp and prominent, and is received during flexion into the
coronoid fossa of the humerus : its superior surface forms part of the surface of the
great sigmoid cavity: the inferior or anterior surface rises gradually from the anterior
surface of the bone, and is covered by a large triangular roughness, the inner part
of which, together with the tuberosity of the ulna at the lower angle of the surface,
gives insertion to the tendon of the brachialis anticus muscle.

The body or shaft tapers from above downwards, and in the upper three-fourths
of its extent is three-sided, and slightly curved with the convexity backwards ; in
the lower fourth it is slender and more cylindrical. It also presents a lateral curve,
with the concavity inwards above, outwards below. The anterior harder, continued
downwards from the inner edge of the coronoid process, is thick and rounded. The
posterior border begins a little below the olecranon process by the meeting of two
lines which limit the triangular subcutaneous surface of the upper end of the bone,
and runs with a sinuous course to the back of the styloid process : it is smooth and
prominent in the upper two-thirds, rounded and ill defined in the lower third. The
external border is in the middle three-fifths of the shaft a sharp rough edge which
gives attachment to the interosseous membrane ; in the lower fifth it is only a
faintly marked line. In the upper fifth this border is continued by two lines, one
passing into the nuicr margin of the coronoid process, and the other to the posterior
extremity of the small sigmoid cavity, near which it becomes very prominent as the

96

THE EONES OF THE UPPER LIMB.

■ (Tn.cPs)

TUBEROSITY

m

s

Fig^ 94.— Anterior view op the right radius and Fig. 95. -Right ulna; postero-ex-
■ ' 3 Lawrence. ) §

THE RADIUS. 97

sitpinaior ridfie, g\\m^ origin to a part of the supinator brevis muscle. Between
these lines, and below the small sigmoid cavity, is a triangular hollow, the fore part
of which lodges the tuberosity of the radius with the insertion of the biceps tendon in
pronation of the hand, while in the hinder part fibres of the supinator brevis arise.
The anterior surface is concave in the upper two-thirds, where the flexor profundus
digitorum muscle takes origin, and in its lower third is marked by an oblique line —
the pronator ridge, which joins the anterior border and limits the attachment of the
pronator quadratus. Above the middle is a foramen for the medullary artery,
directed upwards. The internal surface is smooth and convex, in the upper two-
thirds giving attachment to the flexor profundus muscle, in the lower third
subcutaneous. The ■posterior surface, more uneven, looks outwards and backwards •,
an indistinct oblique line, descending from the supinator ridge to the posterior
border at the junction of the upper and middle thirds of the shaft, limits a trian-
gular area, which extends over the outer side of the olecranon and gives attachment
to the anconeus muscle ; below this a longitudinal ridge divides the surface into
an inner portion, smooth, and covered by the
extensor carpi ulnaris, and an outer part,

more irregular, and impressed by the ex- ant. border^

tensor muscles of the thumlj and index
fingers.

The inferior extremity presents a l[

rounded head, from the inner and back
part of which a short cylindrical eminence,
the styloid process, projects downwards,
giving attachment in front and below to Fig. 96. -Transversk section through the
the internal lateral ligament of the wrist- middle of the bones of the forearm,

joint, and externally to' the triangular fibro- '"™ ''«'= interosseous membrane, in

J.,' „, JJ1 * ,• T supination. G. D. T.) i

cartilage. ihe neaa bears two articular

surfaces, an inferior, semilunar and flat-
tened, upon which the triangular fibro-cartilage of the wrist plays ; and a lateral,
narrow and convex, which is received into the sigmoid cavity of the radius.
The head and the styloid process are separated posteriorly by a groove, which is
traversed by the tendon of the extensor carpi ulnaris ; and inferiorly by a depres-
sion, into which also the triangular fibro-cartilage is inserted.

The ulna is placed in its whole length under the skin at the back of the forearm.
The subcutaneous tract comprises the triangular surface on the back of the
olecranon, the posterior border of the shaft, which lies at the bottom of a longi-
tudinal groove between the flexor and extensor muscles, and, in the lower third, a
narrow strip of the internal surface leading down to the styloid process : the latter
projects in the supine position of the hand at the inner and posterior part of the
wrist ; but when the hand is pronated, the outer and fore part of the head of the
ulna becomes superficial and prominent between the tendons of the extensor carpi
ulnaris and extensor minimi digiti muscles.

THE RADIUS.'

The radius is the external of the two bones of the forearm, and extends from
the humerus to tlie carpus. It articulates with the humerus, the ulna, and the
scaphoid and lunar bones of the car|)us.

The superior extremity or head, is disc-shaped, with a smooth vertical

• In anatornioal description the forearm is .suppo.sed to be jjlaced in suiiinatioii, with the thumb
directcJ outwards and the palm of the liand looking forwards.

98

THE BOXES OF THE UPPER LIMB.

SUPIWATOB

\

margin. It presents on its summit a depression, which articulates with the

capitellum of the humerus, and is surrounded by. a convex part, broadest internally

where it glides upon the groove internal to
the capitellum. The smooth, short, cylin-
drical surface of the vertical margin, likewise
broadest internally, rotates in the small sig-
moid cavity of the ulna, and within the
orbicular ligament. The head is supported
on a constricted portion, named the necJc.

The shaft or body is larger below than
above, and slightly curved, with the convexity
directed outwards and backwards. On its
an tero -internal aspect superiorly, where it is
continuous with the neck, is the Ncipital
tuherodfy, to the posterior rough portion of
which is attached the tendon of the biceps
muscle. Below the bicipital tuberosity the
shaft has three surfaces, of which the external
is only indistinctly marked off from the others
by smooth, rounded anterior and iwsterior
lorders, while the anterior and ]30sterior sur-
faces are separated in their middle three-
fifths by a sharp, prominent internal dorder
which gives attachment to the interosseous
membrane. The anterior surface is limited
above by the prominent anterior ol)lique line,
running from the lower part of the tube-
rosity downwards and outwards to form the
anterior border, and giving origin to a part
of the flexor sublimis digitorum ; below this
the surface is grooved longitudinally for the
flexor longus pollicis muscle ; and at the
lower end it is expanded, and presents a
flattened impression for the insertion of the
pronator quadratus, which also occupies a
small triangular surface on the inner side of
the bone in its lower fifth : above the middle
of the anterior surface is the foramen for the
-medullary artery, directed upwards into the
bone. The posterior surface is marked at the
junction of its upper and middle thirds by
the jjosterior ohlique line, which limits supe-
riorly the impression of the extensor ossis
metacarpi pollicis ; below this is another
small obhque impression for the extensor
brevis pollicis. The external surface is convex
transversely as well as longitudinally, and is
marked near the middle, at its most prominent
part, by a rough impression for the insertion

of the pronator teres. Above this, the area between the anterior and posterior

oblique lines gives insertion to the supinator brevis.

The lower extremity of the radius, broad and thick, presents inferiorly a

large surface which articulates with the carpus, and internally a small one which

EXT. BBCV '

i 1

Fig. 97. — Right radius : posterior
(Drawn by T. W. P. Lawrence.)

THE RADIUS. 99

articulates with the iihia. The carpal articular surface, concave and oblique, is
divided by a line into a quadrilateral internal part which articulates with the lunar
bone, and a triangular external part which articulates with tlie scaphoid bone. The
nlnar ariicular surface is placed at a right angle with the inferior surface, and is
concave from before backwards, forming the sigmoid caviiij, which plays over the
rounded head of the ulna. To the smooth border between the carpal and ulnar
articular surfaces the base of the triangular fibro-cartilage is attached. At the outer
part of the inferior extremity the styloid process projects downwards, stout and
pyramidal, giving attachment to the external lateral ligament of the wrist-joint.
The posterior border of the lower articular surface descends farther than the anterior,
and is roughened for ligamentous attachment. Anteriorly, a prominent transverse
ndge forms the lower limit of the impression of the pronator quadratus, and between
this and the scaphoid articular facet is a small triangular area occupied by a strong
part of the anterior ligament of the wrist-joint. On its external and posterior
aspects the inferior extremity of the radius is marked by grooves, which transmit
the extensor tendons. Thus, on the external border is a fiat groove directed down-
wards and forwards, which lodges the
extensor ossis metacarpi and extensor
brevis pollicis ; and on the posterior
surface are three grooves, the middle
one of which, oblique and narrow, and exi

bounded externally by a prominent
tuhercle, lodges the extensor longus
pollicis ; while of the two others,
which are broad and shallow, the
external, sul)divided by a slight ele- f

vation, gives passage to the extensor t. ^ t

■,. T 1 . T , . l<lg. 98. — LoWKR EXTREMITIES OF RIGHT RADIUS AND

carpi radialis longior and brevior, ulna, in supination, from below. (Drawn by

and the internal transmits the ex- T. W. P. Lawrence.) |

tensor communis digitorum and The dorsal surface is uppermost.

extensor indicis. Immediately above

the first mentioned groove on the outer side is a small triangular mark, into which

the tendon of the supinator longus is inserted.

The outermost <rroove is separated anteriorly from the impression of the pronator quadratus
by a prominent etlp-e which is continued ui)\vards from the transverse ridge of the front of
the lower extremity, and to which the posterior annular li^rament is attached, while posteriorly
it is limited by a less marked elevation descending;: on the back of the styloid process. The
•rroove of the extensor longus pollicis is bounded externally by the tubercle, internally by a
small, often indistinct, ridjie ; and a sharp border projects between the innermost {jroove and
the si-rmoid cavity. The several prominences <;-ive attachment to fibrous septa, which with
the annular li^jament convert the j,'rooves into canals for the passaj^e of the tendons.

The radius is for the most part deeply placed. The head and shaft are entirely
covered by muscles. At the lower end the styloid process comes to the surface
between the tendons of the extensor muscles of the thumb and forms a projection on
the outer side of the wrist, lower down than the styloid process of the ulna : the
tubercle on the back of the lower end of the bone may also be readily felt beneath
the skin.

The relative lenjrth of the forearm to the arm is expressed by the liumcyd-rddidl or anti-

, 7 • I • 7 /len^''th of radius x 100\ ,, ,. . ^. ^ , • i • j j.x,

bracluai uitlcrl ). the rantre oi variation of which in man and the

V. lenjrth of humerus /

anthropoid apes is shown by the followinjr examples, viz. — Eskimo, 71 ; European, 74 ;

Australian. 77 : Netrro. 7!): Andamanese, 81 ; gorilla. 80; chimpanzee. !)0 ; and orang, 100.

The index is higher in the tVctus and infant, and diminishes during the period of growth.

H 2

100

THE BONES OF THE UPPER LIMB.

a?HE CARPUS.

The carpus is composed of eight short bones, which are disposed in two rows,
four in each. Enumerated from the radial to the ulnar side, the bones which con-
stitute the first or superior row are named scaphoid, lunar, pyramidal, and pisijorm ,
those of the second or inferior row are the trapezium, trapezoid, os magnum, and
tmciform.

The dorsal surface of the carpus is convex, the palmar is concave from side t?
side, the concavity being bounded by four prominences, one at the outer and one a,;

Fig. 99. — The bones op the right hand: A, prom before; B, from behind. (Allen Thomson. ) ^

s, scaphoid ; I, lunar ; c, pyramidal ; ju, pisiform ; f, trapezium ; next to it the trapezoid, and then
lihe OS magnum, both not lettered ; u, unciform.

I to V, the metacarpal bones ; 1, 3, first and second phalanges of the thumb ; 1, 2, 3, the first,
second, and third phalanges of the little finger, and similarly for the other three fingers, not marked ;
* one of the sesamoid bones of the thumb seen sideways.

ihe inner extremity of each row. The anterior annular ligament is stretched across
between these prominences, so far as to form a canal for the transmission of the
flexor tendons.

The superior surfaces of the scaphoid, lunar, and pyramidal bones form, when in
apposition, a continuous convexity which corresponds with the concavity presented

Fig. 100. — Semi-diagrammatic view op the right carpus

AND PART OP the METACARPAL BONES, PROM BEFORE,
THE CARPAL BONES BEING SLIGHTLY SEPARATED TO SHOW
THE MODE OP THEIR CONNECTION WITH EACH OTHER.

(Allen Thomson. ) |

1, scaphoid bone; 2, lunar; 3, pyramidal; 4, pisiform;
5, trapezium, the figure is placed upon the ridge, to the
inside of which is the groove for the tendon of the flexor
carpi radialis ; 6, trapezoid ; 7, os magnum ; 8, unciform,
the figure is placed on the unciform process. The articula-
tion of the fourth metacarpal bone with the os magnum is-
rei^resented somewhat too large.

by the radius and the triangular fibro-cartilage, while the pisiform bone is attached
in front of the pyramidal, with which alone it articulates. The line of articulation
between the superior and inferior rows is concavo-convex from side to side, the

THE CARPUS.

101

Fig. 101. — Right scaphoid bone : A, from outer side

AND BEHIND : B, FROM BEFORE AND INNER SIDE. (G. D. T. *

trapezium, trapezoid and os magnum bounding a cavity which lodges the external part
of the scaphoid, and the os magnum and unciform rising up in a convexity, which is
received into a hollow formed by the scaphoid, lunar, and pyramidal bones.

The scaphoid bone, the largest and most external of the first row, lies with its
long axis directed outwards and doivnwards. It has a concave surface, which looks
downwards and inwards, and
articulates with the os magnum ;
Dn the opposite side are two
convex articular surfaces, an
upper for the radius, and a
lower for the trapezium and
trapezoid bones of the second
row ; these appi'oach so near to
one another behind, that the
dorsal free surface is reduced to
a narrow gi'ooved transverse
strip, to which the posterior liga-
ments of the wrist are attached. At the inner extremity is a small orescentic
surface for articulation with the lunar bone ; while the outer end is produced
into a stout conical iuherosiiy, which projects forwards and gives attachment to the
annular ligament. The scaphoid articulates with five bones, viz., the radius, lunar,
trapezium, trapezoid, and os magnum.

The lunar bone (semilumir), irregularly cubic, is characterized by the deep
conca\aty from before backwards of its inferior surface, which rests on the head of
the OS magnum, and commonly also by a bevelled edge
slightly on the unciform bone. Its external surface is
crescentic and vertical, and articulates with the scaphoid
bone : its internal surface looks downwards and inwards,
is much deeper and narrower than the external, and
articulates with the pyramidal. The convex superior
surface, which articulates with the radius, extends like
that of the scaphoid farther backwards than forwards,
and hence the anterior free surface is deeper than
the posterior. The 'lunar articulates with five bones,
viz., the radius, scaphoid, pyramidal, os magnum, and
unciform.

The pyramidal bone (nineiform) is situated with
its blunted apex directed downwards and inwards : the
base has the shape of a half-oval, and articulates
with the lunar bone. There are three surfaces : the
inferior, concavo-convex from without inwards, articu-
iates with the unciform bone ; the anterior is dis-
tinguished by having a smooth circular facet on its
inner half for articulation with the pisiform bone ; and
the supero-posterior presents at the base a small articular
facet entering the wrist-joint, but is for the most part
rough for the attachment of ligaments. The pyramidal
articulates with three bones, viz., the lunar, pisiform, and
unciform.

The pisiform bone lies on a plane anterior to the
other bones lA' the cartjus. In form it is spheroidal, with

•z. I ^1 t T i. 1 i.- 11 r\ •*. 1. Fig- 104.— Ill«HT PISIFORM

Its longest diameter directed vertically. On its posterior "^^j^j^^ ^,j,jj, the outkk side
aspect is an oval articular surface for the pyramidal and i!kiiim> {a l) T.)

Fig. 102. — Right lunar

BONE, PROM THE INNER
side and BELOW (G.

T.)

D.

Fit

. 103. — Right pvkamidal
rone, from before and
outer side. (g. d. t.)

10;

THE B0NE8 OF THE UPPER LIMB.

Fig. 105. — Right trapezium,

FROM BEFORE. (G. D. T. )

bone : this surface does not extend the whole length of the pisiform bone, but
leaves a small free projecting portion below. The inner side of the bone is
generally convex and somewhat rough. The outer side is smoother and slightly
concave.

The trapezium is the most external of che second row of carpal bones. It
presents a rhombic form when seen in its dorsal or palmar aspect, but with the
lower angle much produced and truncated. Its anterior surface is marked by a
vertical groove traversed by the tendon of the flexor carpi radialis muscle, and

externally to the groove by a ridge or tuberosity, one of
the four prominences which give attachment to the an-
terior annular ligament. Of the internal sides of the
rhomb, the superior articulates with the scaphoid and
the inferior with the trapezoid ; while a small facet
on -the prominent lower angle is for the second meta-
carpal bone. Of the external sides, the superior is free,
and the inferior presents a smooth surface, convex from
behind forwards, and concave from without inwards,
which articulates with the metacarpal bone of the thumb,
and is separated by a small interval from the surface
for the second metacarpal bone. The trapezium articu-
lates with four bones, viz., the scaphoid, trapezoid,
and first and second metacarpals.

The trapezoid bone is considerably smaller than
the trapezium. Its longest diameter is from before
backwards. Its posterior free surface is much larger
than the anterior. The external inferior angle of the
anterior surface is distinguished by being prolonged a
little backwards between the articular surfaces for the
trapezium and second metacarpal bone. The superior
surface articulates with the scaphoid ; the external with
the trapezium ; the internal with the os magnum ;
and the inferior by a large surface convex from side to
side with the second metacarpal bone. The trapezoid articulates with four bones,
viz., the scaphoid, trapezium, os magnum, and second metacarpal bone.

The OS magnum is the largest of the carpal bones. In form it is elongated
vertically, nearly rectangular below, rounded above. The upper extremity or head

articulates superiorly with the lunar
bone by a convex surface, extending
farther down behind than in front,
and prolonged on the outer side for
the scaphoid. A oiecJc is formed
beneath by depressions on the an-
terior and posterior surfaces. The
anterior surface of the bone is much
narrower than the posterior. The
posterior surface projects downwards
at its internal inferior angle. On
the outer side, beloAV the surface
for the scaphoid, is a short surface
for the trapezoid bone ; and on the
Inner side is a vertically elongated surface which articulates with the unciform bone,
inferiorly, this bone articulates by three distinct surfaces, of which the middle is
much the largest, with the second, third, and fourth metacarpal bones. The os

Fig. ]06. — Right trapezoid

BONE : PALMAll ASfECT.

{(i. D. T.)

Fig. 107. — ^RiGHT OS MAGNUM : A, inner view;

B, OUTER TIEW. (Gr. D. T.)

THE METACARPUS. 103

magnum articulates with seven bones, viz., the scaphoid, hmar, trapezoid, unciform,

and second, third, and fourth metacarpal bones.

The unciform bone is readily distinguished by the large hook-like process,

projecting forwards and curved slightly outwards, on

its anterior surface. Seen from the front or behind,

it has a triangular form. Its external surface is

vertical, and articulates with the os magnum ; its

inferior surface is divided into two facets which

articulate with the fourth and fifth metacarpal

bones ; its superior surface, meeting the pyramidal

is concavo-convex, inclines upwards and outwards

towards the head of the os magnum, and is separated

. , „ , 1 1 1 r i.1- • J? • I" Fig- 108. — Right unciform

internally by a rough border rrom the mterior surlace. bojj^. f^qji ^he outer side

At the upper angle, externally, there is usually a and below. (G. D. T.)

narrow facet which touches the lunar bone. The

unciform articulates with five bones, viz., the os magnum, lunar, pyramidal, and

fourth and fifth metacarpal bones.

Varieties. — An increase in the number of carpal bones is occasionally met with. This
may arise from the division of one of the normal bones, as has been seen in the case of the
scaphoid, lunar, trapezoid, and magnum ; or it may be due to the persistence of an additional
element, the c-v cnttrah-, which is placed on the dorsal aspect of the hand between the scaphoid,
mag-num and trapezoid, and which is normally present as a cartilaginous rudiment in the
foetus (p. 143). Another form of supernumerary ossicle results from the separation of the
styloid process of the third metacarpal bone. (W. Gruber, '' Ueber das Os centrale Carpi des
Menschen," 1883 ; Leboucq, '• De raugmentation numerique des os du carpe hvimain," Ann.
de la Soc. de Med. de Gand, 1884.)

THE METACABPUS.

The metacarpus, the part of the hand supporting the fingers, consists of five
long bones, which diverge slightly from each other, and are numbered from
without inwards.

The metacarpal bones are placed in a segment of an arch transversely, and being
at the same time slightly curved longitudinally, they present a concavity directed
forwards. They are terminated at their carpal extremities by expanded bases of
different forms, and at the digital ends by large rounded heads. The first meta-
carpal bone is broader and shorter than the others. The second is the longest of
all, the third, fourth, and fifth decrease regularly in length, according to their
position from without inwards.

The shaft of the first metacarpal bone is somewhat compressed from before
backwards ; the dorsal surface is slightly convex ; on the palmar aspect is a rounded
longitudinal ridge, placed nearer to the iimer than the outer border. The shafts of
the others are three-sided, presenting a surface towards the back of the hand, and
towards the palm a smooth margin between the two lateral surfaces. They are most
slender near the carpal extremity, and become gradually thicker towards the head.
The dr>r8al surface of each is triangular, being bounded by lines which, proceeding
from the sides of the head, pass upwards and converge in the second, third, and
fourth metacarpal bones opposite the middle of the carpal extremity, and in the fifth
towards its inner side.

The tmulH articulate with the proximal phalanges. Their smooth, rounded
surfaces are broader, and extend farther, on the palmar than on the dorsal aspect
of the bones ; and on each side is a tubercle with a hollow below it for the attach-
ment of the lateral ligament.

]04

THE BONES OF THE UPPER LIMB

The carpal extremity presents distinctive peculiarities in each metacarpal bone.
That of the first has a saddle-shaped articular surface, concave from before back-
wards, and convex from side to side, for articulation with the trapezium, and.

PHALANCEAl.
ARTIC.SUBF.

Fig. 109. — First metacarpal

BONE OF THE RIGHT HAND :
PALMAR ASPECT. (Gr. D. T.

2v-STYL0ID PRDC.

Fig. 110. — Second METACARPAL

BONE OF T'JE RIGHT HAND :
PALMAR ASPECT. (G. D. T. )

Fig. 111. — Third metacarpal

BONE OF THE RIGHT HAND,
FROM BEHIND. (Gr. D. T.)

Fig. 112. — Fourth metacarpal bone of

THE RIGHT HAND : RADIAL SIDE.

(G. D. T.

Fig. 113. — Fifth metacarpal bone op

THE RIGHT HAND : DORSAL ASPECT.

(G. D. T.)

externally a slight prominence, to which the extensor ossis metacarpi poUicis is
attached. The second is notched to receive the trapezoid bone ; on the
radial side is a small facet for the trapezium ; the more prominent ulnar lip
articulates superiorly by a narrow surface with the os magnum, and internally with
the third metacarpal bone ; and posteriorly, close to the articulation wdth the
trapezium, is a rounded mark where the extensor carpi radiahs longior is inserted.

THE DIGITAL PHALANGES,

105

The third bone articulates above with the os magnum, and on the sides with the
contiguous metacarpal bones ; at its posterior and outer angle it forms a projection
upwards, sfijloid process, immediately below which, on the dorsal aspect, is an im-
pression for the insertion of the extensor carpi radialis brevior. The fourth
articulates principally with the unciform bone above, but also by a small facet at
the posterior and outer corner with the os magnum : on its radial side are two
small rounded facets, and on the ulnar side a slightly concave semi-elliptical surface,
for articulation with the adjacent metacarpal bones. The fifth articulates above
with the unciform bone by means of a saddle-shaped surface directed slightly
outwards, and externally with the fourth metacarpal bone ;
while on its ulnar side there is a broad tuberosity for the
insertion of the extensor carpi ulnaris.

THE EIGITAIi PHALANGES.

The phalanges (internodia) are fourteen in number, three
for each hnger, but only two for the thumb.

Those of the first roiv are slightly curved like the meta-
carpal bones. Their dorsal surfaces are smooth and transversely
convex ; the palmar are flat from side to side, and bounded by
rough margins, which give insertion to the fibrous sheaths of
the flexor tendons. Their proximal extremities are thick, and
articulate each by a transversely oval concave surface with
the corresponding metacarpal bone. Their distal extremities,
smaller and more compressed antero-posteriorly, are divided by
a shallow groove into two condyles.

Those of the middle row are four in number. Smaller
than those of the preceding set, they resemble them in form,
with this difference, that their proximal extremities present, on
the articular surface, a slight middle elevation and two lateral
depressions, adapted to articulate with the condyles of the first
phalanges.

The terminal or ungual phalanges, five in number, have
proximal extremities similar to those of the middle row, but with
a depression in front, where the deep flexor tendon is inserted.
They taper towards their somewhat flattened and expanded free
extremities, which are rough and raised round the margins and
upon the palmar aspect in the so-called ungual process.

Fig. 114. — The pha-
langes OF THE MID-
DLE finger: PALMAK
ASPECT. (G. D. T.)

In each digit the proximal phalanx is the longest, and the distal
phalanx the shortest. CoUectivelj', the phalanges of the middle finger
are the longest ; then follow in order, the ring, the index, and the

little fingers, and lastly the thumb. The greater prominence of the index in relation to the
ring finger, which is observed sometimes in the complete hand, is due entirely to the length
of the metacarpal bone (Braune and Fi.scher, Arch. f. Anat., 18S7).

Sesamoid bones. — A pair of sesamoid bones is placed in the palmar wall of the
metacarpo-phaiangeal articulation of the thumb ; and similar nodules, single or
double, are sometimes found in the corresponding joint of one or more of the other
fingers, mosc fretjuently of the index and little fingers.

106

THE BONES OP THE CJPPER LIMB.

OSSIFICATION OF THE BONES OP THE UPPER LIMB.

With the exception of the clavicle, all the bones of the upper limb begin to ossify in
cartilage

The clavicle begins to ossify before any other bone in the body. Its ossification com-
mences before the deposition of cartilage in connection with it, but afterwards progresses in
cartilage at both ends, as well as in fibrous substance. It is formed from one principal

Fig. 115. — OssincATioK of the olavicle. (R. Quain.)

a, the clavicle of a foetus at birth, osseous in the shaft, 1,
and cartilaginous at both ends.

b, clavicle of a man of about twenty -three years of age;
the shaft, 1, fully ossified at the acromial end; the sternal
epiphysis, 2, is represented rather thicker than natural.

centre, appearing about the 6th week, to which is added an epiphysis at the sternal end.
The epiphysis appears from the 18th to the 20th year, and is united to the shaft about the
2.5th year.

The scapula is ossified in two principal pieces, one forming the body or scapula proper, and
the other the coracoid process, which is generally regarded as representing the independent

1 year. 15 or 16 years. 17 or 18 j'ears 22 years.

Fig. 116. — Ossification of the scapula. (R. Quain.)

], scapula proper, including the body and spine ; 2, coracoid ossification; 3, 5, nuclei of acromion;
4, epiphysis at the lower angle ; 6, epiphysis on vertebral border.

In A, ossification has commenced in the coracoid process. In B the coracoid process (represented as
too little ossified in the figure) is now partially united at its base, and centres have ap^jeared in the
acromion and at the lower angle. In C, a second point has appeared in the acromion, and a long
epiphysis on the vertebral border. In D, the acromion, and the epiphysis of the vertebral border are
still separate.

and often largely developed coracoid bone of the monotremata and lower vertebrates. The
centre of the body appears near the head, about the 7th or 8th week, and gives rise to a
triangular plate of bone, towards the upper margin of which, about the 3rd month, the spine
appears as a slight ridge. At birth, the coracoid and acromion processes, the base and inferior
angle, the edges of the spine and of the glenoid cavity are cartilaginous. The greater part of
the coracoid process is formed from a centre which appears in the first year, but a small part
at the base of the process, including the upper extremity of the glenoid cavity, is a separate
ossification {suljcoracoicT). commencing about the tenth year.^ The coracoid process joins the
body about the age of puberty, and at this time epiphyses make their appearance. In the
acromion two, sometimes three, nuclei appear between the llth and 16th years; they soon
coalesce, and the resulting epiphysis is united to the spine from the 22nd to the 2.oth year.
The cartilage of the base, which it may be noticed corresponds to a more largely developed

^ It is believed by some anatomists that the subcoracoid ossification is the true coracoid element of
the shoulder-girdle, and that the coracoid process represents the precoracoid of reptiles (Sabatier) or the
epicoracoid of monotremes (Howes).

OSSIFICATION OF THE BONES OF THE UPPER LIMB.

107

permanent cartilage or bone. x)q)rasctij)iihir. found in many animals, becomes the seat of
ossification about the l(3th to the 18th j'ear, by the appearance of a nucleus at the inferior
angle, and thei-eafter of a line of osseous deposit extending upwards throughout its length. A

Fig. 117. — Posterior aspecp of the sternum

AND RIGHT SHOCLDER-GIRDLE FROM A

fcetus of about four MONTHS. (Flower
after Parker. ) 1^

The dotted paits are cartilaginous; osf,
omosterniim of Parker, lateral part of epi-
sternum of Gegenbaiir, aftepwards becoming
the interai-ticular tibro-cartilage ; jjc, pre-
coracoid of Parker : a, acromion : cl, sbaft
of clavicle ; mss, mesoscapular segment of
Parker : c, coracoid ; (/c, glenoid cavity ; ;///,
glenoid border ; cb, coracoid border ; a/,
anterior or supraspinous fossa ; ^)/', posterior
or iiifraspinous fossa ; ss, suprascaijuiar
border.

thin lamina, in two pieces, is also added along the upper surface of the coracoid process, and
another at the margin of the glenoid cavity. These epiphyses are united about the 2.5th year.
In the hujnerus a nucletis appears near the middle of the shaft in the 8th week. It
gradually extends, until at birth only the ends of the bone are cartilaginous. In the 1st
year the nucleus of the head appears, and during the 3rd year that for the great tuberosity.

Fig. lis. — Ossification of the humerus. (R. Quain.)

A, from a full-grown foetus ; P>, in the second year ; C, at three years ; D, at the fifth year : F, at
about flic twelfth year ; F, at the age of puberty.

1, the primary centre for the shaft : 2, nucleus for the head ; 3, that for the great tuberosity ; 4,
for the capitellum and adjacsnt part of the trochlea : .'., for the internal condyle : 6, for the inner part
of the trochlea; 7, for the external condyle. In this and the following figures the more advanced
bones are shown on a smaller scale than the earlier ones.

The lesser tuberosity is either ossified from a distinct nucleus which appears in the 5th year,
or by extension of o.ssification from the great tuberosity. These nuclei join together about
the <jth year to form an epiphysis, which is not united to the shaft till the 20th year In
the cartilage of the lower end of the bone four separate nuclei are seen, the first appearing
in the capitellum in the 3rd year. The nucleus of the internal condyle appears in the 5th
year that of the trochlea in the 11th or 12th year, and that of the external condyle in the
13th or 14th year. The nucleus of the internal condyle forms a distinct epiphysis which
unites with the shaft in the 18th year: the other three nuclei coalesce to form an epiphysis,
which in united to the shaft in the UJth or 17th year.

The radius is develojjed from a nucleus which appears in the middle of the shaft in the 8th
week and from an epiphysial nucleus in each extnanlty which only api)ears some time after

108

THE BONES OF THE UPPER LIMB.

birth. The nucleus in the carpal extremity appears at the end of the 2nd year, while that of
the head is not seen till the oth or 6th year. The superior epiphysis and shaft unite about the
17th or 18th year ; the inferior epiphysis and shaft unite about the 20th year.

Fig

119. — Ossification of the
KADius. (R. Quain. )

A, the radius of a full-grown
foetus ; B, at about two years of age ;
C, at five years ; D, at about eighteen
years.

1, shaft ; 2, ossific point of the
lower epiphysis ; 3, that of the upper
end. In D, the upper epiphysis is
united to the shaft, while the lower
is still separate.

The ulna is ossified similarly

to the radius, but begins a little

later. The nucleus of the shaft

appears about the 8th week,

that of the carpal extremity

in the 4th or 5th year. The

upper extremity grows mainly

from the shaft, but at the end

of the olecranon a small epiphysis is formed from a nucleus which appears in the 10th

year. This epiphysis is united to the shaft about the 1 7th year ; the inferior epiphysis about

the 20th year.

From what is stated above it appears that in the bones of the arm and forearm the
epiphyses which meet at the elbow-joint begin to ossify later, and unite with their shafts
earlier, than those at the opposite ends of the bones, whereas in the bones of the thigh and leg

Fig. 120. — Ossification of the
ULNA. (R. Quain.)

A, the ulna at birth ; B. at the
end of the fourth year ; C, of a
boy of about twelve years of age;
D, of a male of about nineteen
or twenty years.

1 , shaft ; 2, nucleus of the lower
epiphysis ; 3, nucleus of the
upper epiphysis. In D, the
upper epi^jhysis is united to
the shaft, while the lower is still
separate.

the epiphyses at the knee-joint
are the soonest to ossify (except
in the fibula) and the latest to
unite with their shafts. In
the bones of the arm and fore-
arm the arterial foramina are
directed towards the elbow ;
in those of the thigh and leg
they are directed away from the knee. Thus, in each bone the epiphj^sis of the extremity
towards which the canal of the medullary artery is directed is the first to be united to
the shaft. It is found also that, while the elongation of the long bones is chiefly the result
of addition to the shaft at the epiphysial synchondroses, the growth takes place more rapidly,
and is continued longer, at the end where the epiphysis is last united ; and the oblique direc-
tion of the vascular canals is due to this inequality of growth, which causes a shifting of the
investing periosteum, and so di-aws the proximal portion of the medullary artery towards the
more rapidly growing end.

The carpus is entirely cartilaginous at birth. Bach carpal bone is ossified from a single
nucleus. The nucleus of the os magnum appears in the 1st year ; that of the unciform in
the 1st or 2nd year ; that of the pyi-amidal in the 3rd year ; those of the trapezium and the
lunar bone in the 5th year ; that of the scaphoid in the 6th or 7th year ; that of the
trapezoid in the 7th or 8th year ; and that of the pisiform in the 12th year.

OSSIFICATION OF THE BOXES OF THE UPPER LIMB.

109

The metacarpal bones and phalang-es are usually formed each from a principal centre for
the shaft and one epiphysis. The ossification of the shaft beyrins about the 8th or 'Jth
week. In the inner four metacarpal bones the epiphysis is at the distal extremity, while in
the metacarpal bone of the thumb and in the phalanges it is placed at the proximal extremity.
In many instances, however, there is also a distal epiphysis visible in the first metacarpal bone
at the age of 7 or 8 years, and there are even traces of a proximal epiphysis in the
second metacarpal. In the seal and some other animals there are always two epiphyses
in these bones. The epiphyses beg-in to be ossified fropi the 3rd to the 5th year, and ar3
united to their respective shafts about the 20th year. The terminal phalanges of the
digits present the remarkable peculiarity that the ossification of their shafts commences at the
distal extremity, instead of in the middle of their length, as is the case with the other
phalanges and with the long bones generally (Schafer and Dixey. Proc. Roy. Soc. xxx. 550
and xxxi. 63).

Fig. 121. — Ossification of toe bones of the hand. (R. Quain.)

A, the condition at birth. The carpus is entirely cartilaginous. Each of the metacarpal bones and
digital phalanges has its shaft ossified.

B, at the end of the first year. The os magnum and unciform have begun to ossify.

C, about the third year. Centres of ossification are seen in the pyramidal and in the proxima.
epiphysis of the first and distal epiphyses of the other four metacarpal bones, and in the pro.xiina.
epiphyses of the first row of phahinges.

D, at the fiftli year. Centres have been formed in the trapezium and h^ter in the lunar bone,
and in the epiphyses of the middle and distal phalanges : (the figure does not show them distinctly in
the middle phalanges).

E, at abfjut the ninth year. Centres have been formed in the scaphoid and trapezoid bones, and the
more developed epiphyses ot the metacarpal bones and phalanges are shown in the tir.st and second
digits separately.

1, OS magnum ; 2, unciform ; 3, pyramidal ; 4, lunar ; 5, trapezium ; G, scaphoid ; 7, trapezoid •
8, metsit.nr[)a,\ bones, the principal pieces ; 8*, four metacarpal epiphyses ; 8', that of the thumb ; 9,
first phalanges ; 9*, their epiphyses ; 9', that of the thumb ; 10, second phidanges ; 10', epiphysis of
tenninal phalanx of thumb ; 11, terminal phalanges of the fingers ; 11*, their epiphyses.

no THE BONES OF THE LOWEE, LIMB.

v.— THE PELVIS AND LOWEE, LIMB.

The divisions of the lower limb are the haunch or hip, thigh, leg, and foot. In
the haunch is the hip-hone, which enters into the formation of the pelvis ; in the
thigh is the femur ; in the leg the tibia and fibula ; and at the knee a large sesamoid
bone, the patella. The foot is composed of three parts, viz., the tarsus, metatarsus,
and phalanges.

THE HIP-BONE.

The hip-l3one, os coxa, or innominate bone, with its neighbour of the opposite side
and the addition of the sacrum and coccyx, forms the pelvis ; it transmits the weight
of the body to the lower limb. It is constricted in the middle and expanded above
and below, and is so curved that, while the upper part is nearly vertical, the lower
part is directed inwards. On the external aspect of the constricted portion is the
acetabulum, a cavity which articulates with the femur, and perforating the inferior
expansion is a large opening, the thyroid or obturator fm-amen. The superior wider
part of the bone forms part of the abdominal wall ; the inferior enters into the
formation of the true pelvis. The hip-bone articulates with its fellow of the opposite
side, with the sacrum, and with the femur.

In the description of this bone it is convenient to recognise as distinct the three
parts of it which are separate in early life, viz., the ilium, os pubis and ischium.
These three portions meet at the acetabulum, in the formation of which they
all take part ; and the os pubis and ischium also meet on the inner side of the
obturator foramen.

The ilium constitutes the superior expanded portion of the bone, and forms a
part of the acetabulum by its inferior extremity. Above the acetabulum it is limited
anteriorly and posteriorly by margins which diverge at right angles one from the
other, and superiorly by an arched thick border, the crest of the ilium. "Viewed from
above, the crest is curved like the letter /, the fore part being concave inwards, the
hinder part concave outwards : it is narrow in its middle third, broadened in front
and behind, and forms a marked projection externally in its anterior third : on it
may be distinguished external and internal lips and an intermediate ridge. The
anterior extremity of the crest forms a projection forwards called the anterior superior
spine of the ilium, and, separated from it by a concave border, and placed imme-
diately above the acetabulum, is another eminence called the anterior inferior spine :
:he projecting posterior extremity of the crest forms the posterior superior spine, and
separated from it by a small notch is the posterior inferior spine, below which the
posterior border of the bone is hollowed out into the ilio-sciatic (or great sciatic) notch.
The external surface or dorsum of the ilium is convex in front, below the prominence
of the crest, and concave behind this. It is traversed by three curved gluteal lines,
which limit the areas of attachment of the gluteal muscles. The posterior or superior
gluteal line leaves the iliac crest about one-fourth of its length from the posterior
superior spine, and curves downwards and forwards towards the hinder part of the
ilio-sciatic notch : the middle gluteal line begins in front at the iliac crest, about one
inch and a half from its anterior extremity, and arches backwards and downwards
to the upper margin of the ilio-sciatic notch : the inferior gluteal line, less strongly
marked than the middle, commences at the anterior border of the ilium, just above
the anterior inferior spine, and is continued backwards nearly parallel to the margin
of the acetabulum to the fore part of the ilio-sciatic notch. Behind the posterior
gluteal line is a narrow semilunar surface, the upper portion of which is rough and
gives attachment to the gluteus maximus muscle, while the lower part is smooth and

THE HIP-BO^!E.

ill

free from muscular attachment. The sickle-shaped space between the iliac crest and
posterior gluteal line above and the middle gluteal line below is occupied by the
o-luteus medius ; and the surface between the middle and inferior gluteal lines gives

SEMIMEMBRANOSUS

INF RAMUS

Fig. r22.— Right iiii'-noxE of male : outer view. (Drawn by T. W. P. Lawrence.) |

origin to the gluteu.s minimus. On the lowest part of this surface, immediately above
the margin of the acetabulum, is a rough elongated mark where tlie reflected head of
the rectus femoris is attached.

The internal surface of the ilium is divided into two parts. The anterior of these
(iliac surface) is the larger : it is smooth and concave, occupied by the iliacus muscle.
and is known as the iliac fossa. Inferiorly, the fossa terminates above the margin of
the acetabulum, and to the inner side of the anterior inferior iliac spine, in a groove

112

THE BONES OF THE LOWEE LIMB.

which lodges the ilio-psoas muscie as it passes from the abdomen into the thigh.
The inner boundary of the groove is formed by an elevation, the Uio-pectineal emi-
nence, marking the nlace of i unction of the pubis and ilium.

IL.IUM

ISCHIUM
Fig. 123. — Right hip-bone of male : inner view. (Drawn by T. W. P. Lawrence.) |

The posterior part {sacral surface) is again subdivided, presenting from below up-
wards— 1, a smooth surface entering into the formation of the true pelvis, and
continuous with the pelvic surfaces of the pubis and ischium, only a faint line indi-
cating in the adult the place of union ; this gives origin to a part of the obturator
internus muscle, and is separated from the iliac fossa by a smooth rounded border, the
ihac portion of the ilio-pectin,eal line ; 2, the uneven auricular surface, in the recent
state covered with cartilage, for articulation with the sacrum, broad in front, and

THE HIP-BONE. 113

extending on to the posterior inferior spine behind ; 3, some depressions for the attach-
ment of the posterior sacro-iliac ligament ; and 4, a rough surface reaching up to
the hinder portion of the iliac crest, and giving origin to parts of the erector and
multifidus spinte muscles.

The iliac crest gives attachment by its outer lip to the tensor vag-inse femoris, obliquus
externus, and latissimus dorsi muscles, and the gluteal fascia ; by its middle ridge to the
internal oblique ; and by its inner lip to the transversalis, quadratus lumborum, and erector
spinaj muscles, and the iliac fascia. To the anterior superior spine are attached the tensor
vaginaj femoris externally, the sartorius in front, and Poupart's ligament internally. The
anterior inferior spine gives origin to the straight head of the rectus femoris muscle. Between
this and the margin of the acetabulum is an impression where the ilio-femoral ligament
is fixed to the bone. The iliac part of the ilio-pectineal line gives attachment to the iliac and
obturator fasciae, and the tendon of the psoas parvus when that muscle is present.

The OS pubis forms the anterior wall of the pelvis, and bounds the thyroid
foramen in the upper half of its extent. At its outer and upper extremity it forms a
part of the acetabulum ; at its inner extremity it presents an elongated oval surface
which forms the articulation with the bone of the opposite side, the junction being
called the symphysis pubis. The part which passes downwards and outwards below
the symphysis is called the inferior or descendiny ramus, the upper part is called the
superior or ascendiny ramus, and the flat portion between the rami is the body. The
deep or pelvic surface of the body is smooth ; the anterior or femoral surface is
roughened near the symphysis by the attachments of muscles. At the superior
extremity of the symphysis is the auyle of the pubis, and extending outwards from
this on the superior border is the voKighpubic crest, terminating in the projecting spine.
The inferior ramus is thin and flattened, and joins the ramus of the ischium. The
superior ramus becomes prismatic, and increases in thickness as it passes upwards
and outwards. Its superior border is the pubic portion of the ilio-pectineal line, a
sharp ridge continued from the iliac portion of the line downwards and inwards
to the pubic spine. The triangular surface in front of this line is covered by
the pectineus muscle ; it is bounded externally by the ilio-pectineal eminence,
and below by the prominent obturator crest, which extends from the pubic
spine to the acetabular margin at the anterior extremity of the cotyloid notch.
Behind the outer part of the crest, on the inferior surface of the ramus, is the
deep obturator yroove, directed from behind forwards and inwards, for the obturator
vessels and nerve.

The pubic crest gives origin to the rectus abdominis and pyramidalis muscles. The pubic
spine serves for the insertion of Poupart's ligament ; and for a short distance outside this
Gimbernat's ligament and the conjoined tendon of the internal oblique and transversalis
muscles are fixed to the ilio-pectineal line. Along the front of the pubic portion of the ilio-
pectineal line the pectineus muscle arises, and to the line itself the pubic portion of the fascia
lata is attached. From the front of the pubis the adductor longus muscle arises in the anglo
between the crest and symphysis, and below this the adductor brevis and upper part of the
adductor magnus. Internally to these the gracilis is attached to the prominent edgf. of
the surface, and externally the obturator externus. Along the margin of the symphysial
surface is a small rough area, which is occupied by the anterior ligament of the articulation,
and is wider in the female than in the male bone (Cleland). The posterior surface of the pubis
gives attachment to part of the obturator internus muscle ; and above this, where a faint line
may sometimes be recognized passing obliquely from the upper margin of the obturator foramen
to the lower end of the symphysis, the levator ani and obturator and recto-vesical fasciae are
fixed together to the bone.

The ischium forms the posterior and inferior part of the hip-bone, and bounds
the thyroid foramen in the lower half of its extent. Superiorly it enters into the
acetabulum : inferiorly it forms a thick projection, the tuberosity, and this part,
diminishing in size, is continued forwards into the ramus. On its posterior border.

114

THE BONES OE THE LOWER LIMB,

behind the acetabulum, a sharp process, the spine, projecting with an inclination
inwards, forms the inferior limit of the ilio-sciatic notch, and is separated from the
tuberosity by a short interval, the sciatic (or S7nall sciatic) notch, against the smooth
margin of which, covered in the recent state with cartilage, the tendon of the obtu-
rator internus muscle glides. In front of this, on the external surface, a horizontal
groove, occupied by the upper border of the obturator externus muscle, lies between
the inferior margin of the acetabulum and the tuberosity. The tuberosity presents

SURFACE
LIGAMENT

ISCHIUM

Fig. 124.— Right HIP-BONE of male, from before and below. (Drawn by T. W. P. Lawrence.) 2

a rough pyriform surface continuous with the internal margin of the ramus, on the
broader superior portion of which are two impressions placed side by side, the outer
for the semimembranosus, the inner for the conjoined origins of the biceps and semi-
tendinosus, Avhile the lower part is ridged and gives attachment to the adductor magnus
muscle ; the inner border is sharp and prominent where the great sacro-sciatic liga-
ment is attached ; and along the outer margin is a faint elongated impression mark-

THE PELVIS. 115

mg the place of origin of the quadratus femoris muscle. The ramus of the ischium
is flattened like the inferior ramus of thj pubis, with which it is continuous on the
inner side of the thyroid foramen.

The ischial spine gives attachment posteriorly to the small sacro-sciatic ligament, exter-
nally to the superior gemellus, and internally to the coccygeus and the hinder fibres of
the levator ani. The inferior gemellus arises from the upper margin of the tuberosity,
below the sciatic notch ; and the inner surface of the ischium gives origin to part of
the obturator internus. On the conjoined ischio-pubic rami, immediately above the inner
margin, in the male bone, is an oval surface to which are attached the cms penis, surrounded
by the ischio-cavernosus muscle, and more deeply the transversus perinei and constrictor
urethris muscles. The smaller and less distinct surface in the female gives attachment to the
cms clitoridis and corresponding muscles.

The acetabulum, or cotijloid cavity, is a cup-shaped hollow, looking outwards, down-
wards, and forwards, and surrounded in the greater part of its circumference by an
elevated margin, which is most prominent at the posterior and upper part ; while at
the opposite side, close to the obturator foramen, it is deficient, forming the cotijloid
notch. Its lateral and upper parts present a broad horseshoe-shaped smooth surface,
which articulates with the head of the femur, and in the recent state is coated with
cartilage ; but the central part of the cup and the region of the notch are depressed below
the level -of the articular surface {fossa acetahuU), lodge a mass of fat and the inter-
articular ligament, and have no cartilaginous coating. Rather more than two-fifths
of the acetabulum are formed from the ischium, less than two-fifths from the ilium,
and the remainder from the pubis. The iliac portion of the articular surface is
the largest, the pubic the smallest : the non-articular surface belongs chiefly to
the ischium.

The thyroid o^s: obturator foramen, also called /or^mew ovale, is internal and inferior
to the acetabulum. In the male it is nearly oval, with the long diameter directed
downwards and backwards ; in the female it is broader and more triangular. In the
recent state it is closed by a fibrous membrane, except in the neighbourhood of the
groove in its upper margin.

The crest of the ilium is subcutaneous, and forms the boundary between the
abdomen and the region of the hip. In front the pubic spine is to be felt through
the integuments, and lower down the inner margin of the united rami of the ischium
and pubis can be followed to the ischial tuberosity, dividing the perineum from the
thigh. The remainder of the bone is tlnckly covered by muscles.

The hip-bone varies greatly in thickness at different parts. The strongest portions are
found along the lines of greatest pressure ; these are, a very thick bar in the ilium between
the auricular surface and the acetabulum, through which the weight of the body is trans-
mitted to the thigh-bones, and a second formed by the ischium, ending in the tuberosity,
which supports the body in the sitting posture. The ilium has also a thick rib running from
the acetabulum to the most prominent portion of the iliac crest, while the bone between this
and the auricular surface, corresponding to the deepest part of the iliac fossa, is very thin.
The floor of the non-articular portion of the acetabulum is also a thin plate of bone, and this
as well as the thin part of the ilium, is occasionally perforated. The chief vascular foramina
penetrate the bone where it is thickest, viz., in the iliac fossa near the auricular surface.
on the pelvic surface of the ilium near the ilio-sciatic notch, on the outer surface of the ilium
between the inferior gluteal line and the acetabulum, and on the ischium between the
acetabulum and tuberosity.

THE PELVIS.

The hip-bones with the sacrum and coccyx form the pelvis.

This part of the skeleton may be considered as divided into two parts by a plane
passing through the sacral promontory, the ilio-pcctineal lines, and the upper border
of the symphysis pubis. 'J'he circle thus completed constitutes the hrim or iniet of

I 1

THE BONES OF THE LOWER LIMB.

the lower or true pelvis ; the
space above it, between the
iliac fossse, belongs really to
the abdomen, but has been

Fig. 125. — Adult male pelvis seen

FROM BEFORE, IN THE ERECT AT-
TITUDE OF THE BODY. (Allen
Thomson.) ^

1, 2, anterior extremities of the
iliac crests in front of the greatest
transverse diameter of the false
pelvis ; 3, 4, acetabula ; 5, 5,
thyroid foi amina ; 6, subpubic angle
or arch.

Fig. 126. — Adult female pelvis.
(Allen Thomson. ) ^

Similarly placed with that shown
in the preceding figure, and illustrat-
ing by comparison with it, the prin-
cipal differences between the male
and female pelvis. The numbers in-
dicate the same parts as in the pre-
ceding figure.

called the upper or false
pelvis. The inferior circum-
ference, or outlet of the pelvis,
presents three large bony
eminences, the coccyx and
the tuberosities of the ischia.
Between the tuberosities of
the ischia in front is the
subpubic arch, which bounds
an angular space extending
forwards to the symphysis,
and is formed by the inferior

Figs. 127 and 12S. — The male and

FEMALE PELVIS, AS SEEN PER-
PENDICULARLY TO THE PLANE OF

THE BRIM. (Allen Thomson. ) \

In Fig. 128 of the female i^elvis
the lines are shown in which the di-
mensions of the i^elvis are usually
measured at the brim.

a, p, antero-posterior or conjugate
diameter ; t, r, transverse or widest
diameter ; o, h, o, h, oblique dia-
meters.

rami of the pubes and the
rami of the ischia. The in-
terval between the sacrum
and coccyx and the ischium
on each side {sacro - sciatic
notch) is bridged over in the

THE PELVIS.

117

recent state by the great saero-sciatic ligaments, which therefore assist in bounding
the outlet of the pelvis.

Position of the pelvis. — In the erect attitude of the body, with the heels
in contact and the toes directed outwards, the pelvis is so inclined that the plane of

Fig. 129. — ilEDIAN SECTION OF A FEMALE PELVIS.

(Beduceil from Niigele.) I

1, symphysis pubis ; 2, promontory of the
sacrum ; 3, coccyx ; 4, anterior superior spine
of ilium ; 5, tuberosity of ischium ; 6, spine of
ischium (the thyroid foramen is not represented so
jiointed below as it generally is in females). The
vertical and horizontal lines in the lower part of
the figure will assist the eye in judging of the
degree of inclination of the pelvis, as illustrated
by the next figure.

the brim of the true pelvis forms an angle
with the horizontal, which varies in differ-
ent individuals from 50° to 60°. The base
of the sacrum is then about 3^ inches above
the upper margin of the symphysis pubis,
and the tip of the coccyx from half an
inch to an inch above the apex of the sub-
pubic arch. The inclination of the pelvis
varies with the position of the lower limbs, and the angle is generally somewhat
greater in the female than in the male.^ The pelvic surface of the sacrum, near its
base, looks much more downwards than forwards, hence the sacrum appears at first
sight to occupy the position of the keystone of an arch ; but being in reality broader

Fig. 130. — Sketch of part of the preceding

FIGURE, SHOWING THE INCLINATION OF THE
BRIM OF THE PELVIS AND ITS AXIS IN THE
ERECT POSTURE. 3

rt, b, line of inclination of the brim of the true
pelvis ; c, f, a line inclining backwards and up-
wards, touching the lower edge of the symphysis
pubis and point of the coccyx ; c. d, axis of the
brim at right angles to the plane of the brim ;
d, h, (J, curved axis of the cavity and outlet.

at its pelvic than on its dorsal aspect, it is a
keystone inverted, or having its broad end
jowest, and is supported in its place chiefly
by ligaments, but also to a slight extent
by the inward projection of the anterior
margin of the iliac articular surface. The
line of pressure of the weight of the body
on the sacrum is directed downwards to-
wards the symphysis pubis, and the resistance of the head of the thigh-bone on each
side is directed upwards and inwards.

The axis of the 2)<il'Vis is the name given to a line drawn at right angles to
the planes of the brim, cavity and outlet, through their central points. The

' Nagele, " Da« weibliche Becken," &c., 1825; Wood, art. "Pelvis," in Cyclop, of Anat. and
PhyK. ; G. H. Meyer, Arch. f. Anat., &c., 1861 ; Fiirst, "Die Maass- und Neigungs-Verhiiltuisse des
BeckeuB," 1875.

118

thp: bones of the lower limb.

posterior wall, formed by the sacrum and coccyx, being about five inches long
and concave, while the anterior wall at the symphysis pubis is only one and a half
or two inches long, the axis is curved ; it is directed at the inlet upwards and
forwards towards the umbilicus, and at the outlet downwards and a little backwards
or forwards according to the level of the coccyx.

Differences according to sex. — The size and form of the pelvis differ
markedly in the two sexes. In the female the constituent bones are more slender
and the muscular impressions less marked ; the height is less, and the breadth and
capacity of the true pelvis greater ; the ilia however are more vertical, and thus
the false pelvis is relatively narrower than in the male ; the inlet of the true pelvis i?
more regularly oval, the sacral promontory projecting less into it ; the sacrum is
flatter and broader ; the depth of the symphysis pubis is less ; the subpubic arch
is much wider, and the space between the tuberosities of the ischia greater.

The average dimensions of the pelvis, as measured in a number of full-sizec
males and females, may be stated as follow, in inches : —

Greatest distance between the crests of the ilia
externally

Distance between the anterior superior spines of
the ilia ........

Distance between the front of the symphysis
pubis and the first sacral spine . . . .

True Pelvis.

Transverse diameter . . . . ,

Oblique diameter

Antero-posterior diameter

Male.

Fkjiale.

H
7k

11

H

7

Brim.

Cavity.

Outlet.

Brim.

Cavity.

Outlet.

5
4

4|
U

4

3^
4

5i
5

5
5

4|

4'

The human pelvis, compared with that of the lower animals, is characterised by its shallow-
ness and breadth, and by the great capacity of the true pelvis ; by the expansion of the ilia,
the length and sigmoid curve of their crests, the massiveness and straightness of the ischial
tuberosities, and the shortness of the symphysis. Similar, although much slighter, variations
in the form of the pelvis are to be recognized in the different races of mankind, the most
important of which is in the relation of the antero-posterior to the transverse diameter, and
is expressed by what is termed the pelvic index. This is measured at the pelvic brim ; the
transverse diameter is taken as the standard = 100, and the proportion of the antero-posterior
diameter to this gives the index. For this purpose the pelves of the two sexes must necessarily
be grouped separately, and the male is usually selected for comparison. The following
examples of the average pelvic index in the male of four races will show the range of varia-
tion : — European, 80 ; Negro, 93 ; Australian, 97 ; Andamanese, 99. Pelves with an index
above 95 are doliclwpellic, from 96 to 90 mesatipellic, and below 90 jjilatyiiellic (Turner).
(Verneau, " Le bassin dans les sexes et dans les races," 1875 ; Garson, Journ. Anat., xvi ;
Turner, Journ. Anat., xx, and " Challenger " Reports, Zoology, xvi.)

THE FEMUR.

The femur or thigh-bone, situated between the hip-bone and the tibia, is the
largest and longest bone of the skeleton. In the erect position of the body it
inclines inwards and slightly backwards as it descends, so as to approach inferiorly
its fellow of the opposite side, and to have its upper end a little in advance of the
lower. It is divisible into the swperior extremity, including the head and neclc and
two eminences called trochanters ; the shaft ; and the inferior extremity, expanded
into an external and an internal condyle.

At the superior extremity of the bone, the necli extends inwards, upwards,

' This diameter may be increased to the extent of one inch or more by movement of tlie coccyx.

THE FEMUK.

119

and slightly forwards, being
set upon the shaft at an angle
of about 125°, The neck is
expanded from above down at
its base, where it meets the shaft
obliquely, but compressed from
before back, so that the vertical
diameter greatly exceeds the
antero-posterior ; the summit
becomes more rounded, and is
somewhat enlarged again as it
joins the head. It is shorter
above and iu front than below
and behiud. On its posterior
surface there may usually be
recognized a shallow horizontal
groove, in which the tendon of
the obturator externus lies.
The head forms more than half
a sphere, and is covered with
cartilage in the fresh state.
Behind and below its central
point is a small oval depression,
the fore part of which givee
attachment to the interarti-
cular ligament of the hip-joint.
In the hollow there are often
one or two small vascidar
foramina.

The great irochanter is a
thick truncated process pro-
longed upwards in a line \vith
the external surface of the
shaft. In front it is marked
by the insertion of the gluteus
minimus. Externally an ob-
lique line directed downwards
and forwards indicates the in-
ferior border of the insertion
of the gluteus medius muscle ;
and lower down the surface is.
bounded by a horizontal line,
which is continued upwards on
the front of the trochanter to
an eminence at the junction
with the neck, the tuhercU
of the femur ; this line marks
the upfXir limit of the vastus
externus. Internally at its
base, and rather Ijehind the
neck, is the trocJuinleric or
difjilal fosm, which gives at-
tachment to the obturator

DIGITAL FOSSA

J. OF QUADHfiTUS .-'-''■'^
NTERTROCM. RIOce

.ROCH....R ^^

ill
1

f

1

SPIRAU LINE

1

GLUTEAL
RIOCE

ARTERIAL FOR*

LINEA ASPERA

ARTERIAL FOHAMEM-

CASTBOCNE^

/PLANTARIS

^\J

7 GASTROCNEMIUS

I TUOEnoSITY

POST. CRUCIAL LICT.

UCIAL LICT.

INTERCONDYLS

Fig.

131. — RioiiT FEMun, FROM BEHIND. (Drawii by
T. W. p. Lawrence.) |j.

120

THE BONES OF THE LOWER LIMB.

ANT
INTERTROC
LINE

Fig. 132. — Upper portion of right femur, from
BEFORE. (Drawn by T. W. P. Lawrence.) |

externus muscle, while close above and in front of this is the impression of the
obtm-ator internus and gemelli muscles. The upper border of the great trochanter
is narrow, and presents an oval mark for the insertion of the pyriformis. The

posterior border is prominent,
and continued into a strong
rounded elevation, the inter-
trochanteric ridge or posterior
intertrochanteric line, which passes
downwards and inwards to the
small trochanter, and limits the
neck posteriorly : above the
centre the ridge is thickened,
marking the attachment of the
upper part of the quadratus fe-
moris ; the enlargement is termed
the tubercle of the quadratus.

The small trochanter, a pyra-
midal eminence, projects from
the posterior and inner aspect of
the bone at the junction of the
neck with the shaft ; its rounded
summit gives attachment to the
tendon of the ilio-psoas muscle.
The neck is separated from the
shaft anteriorly by the anterior
intertroclmnteric line, or upper
part of the spiral line, a broad
rough line commencing at the
tubercle of the femur and di-
rected obliquely downwards and
inwards a finger's breadth in
front of the small trochanter ;
it indicates the attachment of
the thick anterior portion of the
capsular ligament of the hip-
joint and the upper border of
the united crureus and vastus in-
ternus muscles.

The shaft is arched from
above downwards, with the con-
vexity forwards. It is somewhat
narrowed in the middle third,
and becomes considerably ex-
panded below. Towards the centre
it is nearly cylindrical, but with a
tendency to the prismatic form, due to the projection of the linea aspera behind, and
a slight flattening of the surface in front ; so that it may conveniently be regarded as
presenting an anterior and two lateral surfaces, although definite lines separating
the surfaces do not exist. All three surfaces, smooth and uniform, are covered by
the crureus and vasti muscles. The lateral surfaces in the middle of their extent
approach one another behind, being only separated by the linea aspera. The linea
aspera is a prominent ridge, extending along the central third of the shaft
posteriorly, and bifurcating above and below. It presents two sharp margins or

POPLITEUS

Fig. 133.-

S'^r. COND-*^

"vr. coNO-*^

-Lower end op right femur, from before.
(Drawn by T. W. P. Lawrence. ) |

THE FEMUR.

12i

lips separated by a narrow interval. The external lip is prolonged up to the great
trochanter, and in its course is strongly marked for about three inches where the
gluteus maximus is attached, constituting the gluteal ridfje. The internal lip is
continued, winding in front of the small trochanter, to the anterior nitertrochanteric
line, and forms the lower part of the spiral line ; it marks the attachment of the
vastus internus. In the interval between the two diverging branches of the linea
aspera a less distinct line, which gives attachment to the pectineus, is seen passing
to the small trochanter. Inferiorly the two lips are prolonged to the condyles
under the name of infernal and external supracondylar lines, enclosing between
them a flat triangular surface of bone, the, jwpl iteal surface of the femur, which forms
the floor of the upper part of the popliteal space. The internal supracondylar line
is interrupted at the upper part where the femoral vessels lie against the bone; it
terminates below in a small sharp projection, the adductor tubercle, giving
attachment to the tendon of the adductor magnus. Above the centre of the linea
aspera is the foramen for the medullary artery, directed upwards into the bone ; a
second foramen is frequently to be seen near the lower end of the line.

To the inner lip of the linea aspera are attached the vastus internus, adductor longus and
adductor magnus muscles, the last also extending upwards on the inner side of the gluteal
ridge, and downwards along the internal supracondylar line. The outer lip of the linea
aspera and the external supracondylar line give attachment to the short head of the biceps
and the external intermuscular septum of the thigh. The adductor brevis is inserted into the
upper third of the shaft externally to the pectineal line. Running downwards from the
tubercle of the quadratus to the level of the small trochanter there is sometimes to be seen a
faint linea qriadmtl, marking the insertion of the quadratus femoris. A small triangular
area below the lesser trochanter, between the pectineal and spiral lines, gives insertion to the
outer fibres of the iliacus. At the lower part of the popliteal surface is a slight roughness on
each side, above the corresponding condyle, where fibres of the two heads of the gastrocnemius,
and externally also the plantaris, arise.

SEMILUNAR
ELLAR
FACET

The inferior extremity presents two rounded eminences, the condyles, united
in front, but separated behind by a deep intercondylar fossa or 7iotch. Their gi'eatest
prominence is directed back-
wards, and their curve, as it
increases towards that part,
may be compared to that of
a partially uncoiled piece of
watch-spring. The external
condyle is the broader and
more prominent in front ;
the internal is the longer and
more prominent laterally.
In the natural position of the
femur, however, the inferior
surfaces of the two condyles
are on the same level. One
Jarge articular surface, coated
continuously with cartilage,
extends over both condyles ;
but opposite the front of the intercondylar fossa it is divided by two irregular, slightly
marked transverse grooves into three parts, a convex surface on each side of the
fossa for articulation with the tibia ; and a grooved anterior surface for the patella.
The patellar surface is of a trochlear Ibrm, being marked by a vertical hollow and
two prominent lips ; the external poition of this surface is wider and more
prominent, and rises higher than the internal. The tibial surfaces are nearly

INTERCOI-lbvi-An rocsA
POST. CRUC. LIST.

Fig. l;J4. — LoWKK KXTKKMITY OK lUOHT FEMUR, FROM

BELOW. (Drawn by T. W. P. Lawrence.) |

132

THE BONES OF THE LOWER LIMB.

©ASTROCNEMIU

parallel, except in front, where the in-
ternal turns obliquely outwards to
reach the patellar surface. On the
exposed lateral surface of each condyle
is a rough tvJjerositij, giving attach-
ment to the respective lateral ligament
of the knee-joint. The external tube-
rosity is the smaller of the two ; above
it is a roundish impression for the outer
head of the gastrocnemius, and below
and behind it an oblique groove, ending
inferiorly in a pit, in which the popli-
teus muscle takes origin : the tendon
of the muscle plays over the smooth
hinder edge of the groove, and sinks
into the hollow when the knee-joint is
fully bent. On the upper part of the
internal condyle, between the adductor
tubercle and the articular surface, is an
impression for the internal head of the gastrocnemius. The floor of the intercondylar
fossa is rough, and presents two impressions where the crucial ligaments are attached :

POPLITEUe

Fig. 135. — Lower portion of right femur :
OUTER VIEW. (Drawn by T. W. P. Lawrence.)

Fig. 136. — Coronal section of the upper end of the femur. (Zaaijer. )

THE FEMUE.

123

that of the auterior ligament occupies the hindmost part of the inner surface of the
external condyle, while that of the posterior ligament is at the inner and fore part
of the fossa, above the curved portion of the internal tibial articular surface.

The head and neck of the femur are deeply placed ; the great trochanter is
covered only by the aponeurosis of the gluteus maximus, and is readily felt, forming
the most prominent part of the hip. The shaft is thickly surrounded by muscles.
The condyles are subcutaneous on each side of the knee, the internal being especially
prominent ; the trochlear surface is concealed by tlie patella during extension, but
in the flexed limb its form can be traced pushing up the muscular covering.

The arrangemeut of the cancellous tissue at the upper end of the femur is shown in
fijr. 136. A system of '• pressure-lamellae," springfing from the compact wall of the lower
side of the neck and the upper end of the shaft internally, ascends radiating inwards to the
head and outwards to the great tro-
chanter ; those passing to the head are
especially dense. These are crossed at
right-angles by a set of '• tension-la-
mellae.'' which start from the outer side
of the shaft, and arch upwards and
inwards to the head and inner side of
the neck. The concave side of the neck
is farther strengthened by a nearly
vertical plate of compact tissue (raJcar
femorale^). which projects upwards into
the spongy substance a little in front
of the small trochanter. At the lower
end of the bone the chief lamellae run
vertically from the compact wall of the
shaft to the tibial articular surfaces.

The average length of the femur in
the European male is a little more than
18 inches, in the female about 17 inches.
It equals about •27.5 of the stature, and
its proportion to the humerus is as 100 : 71.

In the erect attitude the inclination of the femur is such that the shaft forms an angle of
about y- with the sagittal plane, and .5^ with the frontal plane ; the former angle is larger
in the female than in the male. The femur also exhibits a torsion similar to that of the
humerus, but usually in the opposite direction, the head being inclined forwards from the
transverse axis of the lower extremity : the mi{ile of turmun varies within wide limits, but is
in the majority of cases between h" and 20° (Mikulicz. Arch. f. Anat., 1878).

The angle between the neck and .shaft of the femur varies much in different individuals.
ranging in the adult from 110° to 140°. It is as a rule smaller in short than in long thigh-
bones, and in women than in men. It is more open in the foetus and child, and decreases
during the period of growth under the influence of the weight of the body ; but it does not
appear to undergo any change after growth is completed (Humphiy. Journ. Anat., xxiii.
273).

Varieties.— The upper part of the gluteal ridge is sometimes very prominent, forming a
thii-tl trnchaiifi-r similar to the process so named in the horse and some other animals. In
some cases there is a hollow, fimxa hyjwtrochantrrica,- in place of or in addition to the ridge.
A marked development of the linea aspera gives rise to the condition known as fhQ pihixtrrrd
femur. The adductor tubercle may be of unusual size, and has been seen forming a projection
three-quarters of an inch in length.

Y'\g. 137. — Transverse section of the femur

IMMEDIATELY ABOVE THE SJIALL TROCHANTER. (G. D. T. )

' Merkel, Virchow's Archiv, lix.

2 Houze, Bull. delaSoc. d'Anthrop., Bnixelles, 1883.

134 THE BONES OF THE LOWER LIMB.

THE PATELLA.

The patella, rotula, or knee-pan, situated at the front of the knee-joint, is a
sesamoid bone developed in the tendon of the quadriceps extensor cruris. It is
compressed from before backwards, and somewhat triangular in shape, with the
apex below. Its anterior surface is convex and longitudinally striated, being
covered by a fibrous prolongation from the extensor tendon ; it presents a few

Fig. 138- RlGHX PATELLA :

A, FROM BEFORE ; B,PR0M:

BEHIND. (Drawn by T.
W. P. Lawrence.) |

In B, the articular surface
is seen, divided by a ridge into
a smaller internal and a larger
external part. On each of
these three facets may be re-
cognized, of which the middle
is the largest and the lower
the smallest, while along the
inner margin there is a narrow
seventh facet.

vascular foramina, and is separated from the skin by one or more bursEe. The
superior border is broad, and sloped from behind downwards and forwards ; it is
occupied, except near the posterior margin, by an impression into which the
common (suprapatellar) tendon of the quadriceps is inserted. The deep surface is
for the most part coated with cartilage for articulation with the femur, and is
divided by a vertical elevation into two parts, the external of which is the larger
and transversely concave, while the internal is convex : below the articular surface
is a triangular depressed and roughened area, covered in the recent state by a mass
of fat r and from the lower angle and sharp margins of this part of the bone the
infrapatellar tendon or ligamentum patelte springs, by which the patella is
attached to the tibia.

THE TIBIA.

The tibia, or shin-bone, is, next to the femur, the longest bone in the skeleton.
It is the anterior and inner of the two bones of the leg, and alone communicates
the weight of the trunk to the foot. It articulates with the femur, fibula, and
astragalus.

The superior extremity or head is thick and expanded, broader from side to
side than from before back, and inclined somewhat backwards from the direction of
the shaft. It forms on each side a massive eminence or tuberosity, on the upper
aspect of which is a slightly concave articular surface for the corresponding
condyle of the femur. The internal tuberosity, somewhat larger than the external,
is rounded, and marked posteriorly by a horizontal groove for the insertion of the
semimembranosus muscle. The external tuberosity forms at the junction of its
anterior and outer surfaces a broad prominent tubercle, into which the ilio-tibial
band of the fascia lata is inserted ; at its posterior and under part is a small flat
surface for articulation with the head of the fibula. The internal condylar surface
is oval in shape, larger than the external, and slightly more hollowed. The external
condylar surface is more nearly circular, and concave from side to side, but rather
concavo-convex (in some cases altogether convex) from before backwards, and is
prolonged for a short distance on the posterior surface of the tuberosity where
the tendon of the popliteus glides. The peripheral part of each articular
surface is flattened, and separated from the condyle of the femur by a semi-
lunar interarticular fibro-cartilage. Between the condylar surfaces is an irregular

THE TIBIA.

125

ILIO -TIBIAL BAND

STYLOID PROO,

?ig. 139. — Rkjht tibia asd fibula, from
BEFORE. (Drawn by T. W. P. Lawrence.) ^

Fi;;. MO. — RiiiirT thua ani> i ihmia, Fiioiyi
BEHIND. (Diawii hy T. W. 1'. Lawrence.) -?t

126

THE BONES OF THE LOWER LIMB.

interval, depressed in front and behind, where it gives attachment to the crucial
ligaments and the semilunar libro-cartilages of the knee-joint, and elevated in the
middle, thus forming the spine, which is received into the intercondylar notch of
the femur. The summit of the spine presents two compressed tubercles, with a
slight intervening hollow, and the condylar articular surfaces are prolonged upwards
on the sides of the process. The depressed surface behind the spine is continued
into a shallow excavation — the piojjliteal notch, which separates the tuberosities on
the posterior aspect of the head. Lower down on the front of the bone, at the
junction of the head and shaft, is situated the tubercle or anterior tuberosity,
marked by the attachment of the ligamentum patellse.

The shaft of the tibia is three-sided, and diminishes in size as it descends for
about two-thirds of its length, but increases somewhat towards its lower extremity.
The internal surf ace w, convex and for the most part subcutaneous ; at the upper

ANT. CRUC. LIGT,
INT. FJBRO-CAHT

TUBERCLE

EXT. FIBRO-CART.

Fig. 141. — Upper extremity of the right
TIBIA, FROM ABOVE. (Drawn by T. W. P.

Lawrence. ) |

Fig. 142. — Transverse section through the

MIDDLE OF THE BONES OP THE LEG, WITH THE
INTEROSSEOUS MEMBRANE. (G. D. T.) |

end, by the side of the tubercle, is a slight roughness where the tendons of the
sartorius, gracihs and semitendinosus muscles are inserted. It is separated from
the external surface by the anterior border, which runs with a sinuous course from
the tubercle to the front of the internal malleolus, having its concavity directed
outwards above, and inwards below ; in its ujoper two-thirds it forms a sharp ridge
known as the crest of the tibia ; in its lower third it is smooth and rounded. The
eternal surface is shghtly hollowed in its upper two-thirds, where it lodges the
belly of the tibialis anticus muscle ; but below the point where the crest disappears
it turns forwards, becomes convex, and is covered by the extensor tendons. The
posterior surface is crossed obliquely in its upper third by the rough popliteal or
oblique line, which runs downwards and inwards from the outer tuberosity, and gives
origin to the soleus muscle : above this is a triangular area occupied by the popliteus
muscle ; while below the line, in the middle third of the shaft, a longitudinal
ridge divides the surface into two portions, an inner giving origin to the flexor
longus digitorum, and an outer, larger, to the tibiahs posticus. A little below the
oblique line, and external to the longitudinal ridge, is a large foramen for the
medullary artery, directed downwards into the bone. The posterior surface is
separated from the internal by the internal border, which is most distinct in the
middle third of the bone, being rounded off above and below, and from the outer
surface by the external border or interosseous ridge, a prominent edge or line, inclined
forwards above, to which the intei osseous membrane is attached.

The inferior extremity, much smaller than the superior, is expanded trans-

THE FIBULA. 127

versely, and projects downwards on its inner side, so as to form a thick process, the
internal malleolus. Inferiorly it presents for articulation with the astragalus a
cartilaginous surface, which is quadrilateral, concave from before backwards, and
having its posterior border narrower and projecting farther downwards than the
anterior ; internally the cartilaginous surface is continued down in a vertical
direction upon the internal malleolus, clothing its outer surface somewhat more
deeply in front than behind. The external surface is hollowed for the reception of
the fibula, and rough for the attachment of ligament, except over a small part along
tlie lower border. The posterior surface of the internal malleolus is marked by a
groove for the tendon of the tibialis posticus, and more externally is a slight
depression where the tendon of the flexor longus hallucis lies.

Both tuberosities of the tibia are subcutaneous, the external forming a well-
marked prominence at the outer and fore part of the knee. The internal surface
of the shaft is thinly covered for a short distance at the upper part by the tendons
of the sartorius, gracilis, and semitendinosus, but in the rest of its extent it is
subcutaneous, together with the continuous surlace of the internal malleolus.
Anteriorly, the tubercle gives rise to a slight elevation below the knee, on which the
body is supported in kneeling, and running down from this the crest is to be
followed, constituting the shin.

_,, . ,i- 1 ■ 1 /lenjjth of tibia X 100 \ ■ ■, ^ oi ■ ^.u -n o.j •

The fcmoro-tihial titdcc — ~ ) is about 81 in the European, 8.^ m

\ length or femur /

the XegTO, and 80 in the Bushman. The tibia is twisted so tliat when the upper extremity

has its longest diameter directed transversely, the internal malleolus is inclined forwards : the

a7ifjle of torsion is commonly between 5^ and 20°, but it may range from 0 to 48° (Mikulicz,

Arch. f. Anat., 1878).

"Varieties. — The shaft of the tibia is sometimes much compressed laterally, and expanded

from before back, the posterior longitudinal ridge being very prominent, so that a transverse

section at the junction of the upper and middle thirds has the form of a narrow lozenge :

such a bone is said to he 2}l(it]/cn''iiiic. A facet at the anterior margin of the lower extremity

for articulation with the neck of the astragalus in extreme flexion of the ankle-joint is rare

in Europeans, but common in some lower races. (iManouvrier, " Sur le pl.itycnemie," &c.,

Mem. Soc. d'Anthrop. Par.. 1S8S ; A. Thomson, "Influence of posture on the form of the

tibia," &c., Joum. Anat. xxiii and xxiv.)

THE FIBULA.

'J'he fibula, or jieroneal hone, is situated on the outer side of the leg ; it is nearly
equal to the tibia in length, but is much more slender. Its inferior extremity is
placed a little in advance of the superior ; and its shaft is slightly curved, so as
io have the convexity directed backwards, and, in the lower half, slightly inwards
towards the tibia.

The superior extremity, or head, somewhat expanded, is produced upwards at
its hindmost part into a conical eminence, known as the styloid process ; in front of,
and inside this is a small oval cartilage-covered facet, looking upwards, inwards and
forwards, for articulation with the outer tuberosity of the tibia ; while more externally
js a slightly excavated surface where the tendon of the biceps femoris is inserted:
the outer side of the head is smooth and subcutaneous. The somewhat constricted
part below the head is distinguished as the neck.

The inferior extremity, or external malleolus, is longer and more prominent
than the internal malleolus ; internally it forms the outer limit of the ankle joint,
and presents a triangular smooth surface for articulation with the astragalus, behind
which is a rough depression where the posterior band of the external lateral ligament
is attached : its anterior border, after projecting rather abruptly forwards, slopes
downwards and backwards : posteriorly it is marked by a shallow groove traversed

128

THE BONES OF THE LOWER LIMB.

IN1FS510S

.■.SijtA&ALL'S-

Kg. 143. — Right riBrLA : isxek
TiEv. (Drawn 1>T T. "VT. P.
La-wrenre, ") i

by the tendons of the peroneus longns and brevis
muscles : externally it is convex and subcutaneous ;
and a triangular subcutaneous surface is continued
up from it for two or three inches on the shaft.

The shaft has foiu" surfaces, separated by as
many prominent lines. Three of these lines are
known as borders, the fourth is the interosseous
ridge. The anierior border is the most prominent ;
it commences at the fore part of the neck, and
takes a straight com'se down the front of the bone
as far as the lower fifth, where it bifurcates, the
one line nmniug to the front of the malleolus, the
other to the back, and enclosing between them the
triangular subcutaneous smface. Immediately in-
ternal to this is the interosseous ridge, so named
from giving attachment to the interosseous mem-
brane ; it is close to the anterior border abo^'e,
but gradually diverges from that as it passes
downwards : it terminates about an inch and a
half above the ankle-joint in the apex of a tri-
angular surface, convex and roughened by the
inferior interosseous ligament, fixiug it to the tibia.
The external border extends the whole length of
the boue, from the styloid process to the back of
the malleolus, inclining inwards in its lower half.
The remaining border, i?iternat, commences at the
inner side of the neck, rims down the shaft for
two-thirds of its length, and then ends by joiniug
the interosseous ridge. The surfaces are : — the
anterior, between the anterior border and the in-
terosseous ridge, narrow above, wider below ; it
gives origin to the extensor muscles of the toes
and the peroneus tertius : the external, broadest of
all. somewhat hollowed at the upper part, and
tm-ning below to the back of the malleolus, thus
indicating the coui"se of the perouei muscles, by
which it is completely covered : the posterior, which
winds to the inner side of the bone in its lower
half : in its upper third it is rough, giving origin
to the soleus, while the rest of its extent is occupied
by the flexor longus hallucis : and the internal,
between the internal border and the interosseous
line, a fusiform surface over the upper two-thirds
only of the shaft, and giving origin to the tibialis
posticus : it is often traversed by an oblique ridge
which gives attachment to a tendinous septum in
the muscle. The foramen of the medullaiy artery
is small, placed on the internal or posterior surface,
about the middle, and is directed downwards.

The head of the fibula projects imder the skin
at the outer and back part of the knee, behind and
somewhat below the level of the prominent outer

THE TAliSUS.

120

tubf.Tosity of the tibia. The shaft is covered by mu--cle--, exc,pt, over tlie tri-
anf^ular surface aVxjve mentioned. The external rnalleolu-s descends lower and j^ro-
jects fartfier l;ackwards than the internal, its point being nearer to the heel hy
about three-<juarter:s of an inch.

THE TARSUS.

The tarsus is composed of s^,-\en bones, \iz., the calcaneurn, astrajralus, navi-
cular, three cuneiform, and cuboid.

The calcanenm or os calcis is the largest bone of the foot. Projecting down
wards and backward.-;, it form- the heel. Above, it articulators with the afitragalus,
and in front with the cuboid Vjone. Its princi[/dl axis extends forward* and
ontward-s from its posterior extremity to the cuboid bone.

The XiiV'iHt poderU/r exiremHij^ux f ube^rosibj, yrciientfi inferiorly two tubercles, which
rest upon the ground, and of which the internal i.s the largei" : its hinder sur^ice is

A B

I

"iT

Fig. 144- — The bo5E3 of thk right foot : A, feom above ; B, fkom bei/jw, i' Alien Thomfsou.) ^
a, navicoliir Jxme ; b, antragaluii ; c, oh calc-i« ; </?, ite tu>>croHity ; e, mtemal cuneifortfi ; /, iniJdlp
cuneiform ; y, external cuneiform ; A, cuboid \n>iie ; I to V, the metatarKal }>one« ; 1, -i, finit and laiw
phalangefi of the great toe ; 1, 2, 3, finit, »econd, and third pbalangeii of the tsecond t^;€.

divided into an upper part, smooth and sef/arated by a bursa from the tendo Achiliis,
a middle part for the attachment of the tendon, and a lower part, convex and
roughened, continued Wow on to the tubercles, and c^jvered hj the thick skin and
fatty pa^l of the heel. The part in front of the tuberosity forms a slightly con-
stricte^l neck. The internal surface of the bone is deeply concave, and its concavity
is surmounted in front by a flattened proox;ss, the msstentaculum tali, which jirojects
inwards near the auU-.nor extremity of the bone on a level with its upf>er surface,
and prfes^^nts inferiorly a groove oc^.-upied by the tendon of the flexor longus hallucis.
The vpper surface has two articular facets for the astragalus, separated by an
oVjlique grryjve in which the interosseous ligament is attached ; the ant<;rior facet,

130

THE BONES OF THE LOWER LIMB.

31 ASTR4G.

Fiff. 145. — Right os calcis, sroji above.

D. T.)

often sLibdivided into two, is placed over the sustentaculum, and is concave ; the
other, posterior and external to this, and larger, is convex from behind forwards and
outwards : the outer end of the groove is much widened, and at its fore part is a

rough surface where the extensor
cuBo.D brevis digitorum takes origin. The

anterior extremity articulates with
the cuboid bone by a surface concave
from above, downwards and out-
wards, and convex in the opposite
direction ; and internal to this, along
the front of the sustentaculum tali,
the internal calcaneo-navicular liga-
ment is attached. The under surface,
projecting in a rough anterior
tutercle, gives attachment to the
inferior calcaneo-cuboid ligaments.
The external surface is on the whole
flat, but often presents at its fore part
an oblique ridge, the jwrofieal spwie,
separating two slight grooves, the
upper for the tendon of the peroneus
brevis, the lower for the peroneus
Ion gas.

The astragalus, or talus, second
in size of the tarsal bones, receives
the weight of the body from the
leg. It articulates with the tibia
above and internally, the fibula ex-
ternally, the OS calcis below, and the
navicular in front. Its longest axis
is directed forwards and inwards.
Its main part is called the hody, the
convex anterior extremity is the head,
and the grooved part behind this is
the neclc. The superior articular
surface occupies the whole of the
upper aspect of the body, and sends
a prolongation downwards on each
of the lateral surfaces of the bone.
The middle part, looking upwards
to the tibia, is convex from before
backwards, broader in front than
behind, with its outer margin longer
than the inner, and curved, while
the inner is straight. The inner
lateral part is narrow, sick le-shaped
and articulates with the internal malleolus ; the outer lateral part, much deeper
triangular, and concave from above down, articulates with the external malleolus
Inferiorly, there are two smooth surfaces, which articulate with the calcaneum.
The posterior of these, the larger, concave from Avithin outwards and forwards, is
separated by a rough depression for the interosseous ligament from the convex
anterior surface, which rests on the sustentaculum tali. The rounded anterior sur-
face of the head articulates with the navicular bone : and at the lower and inner

. CALC. MAV.LIC-^

ALCANEUM

NTEROSS.CRODVE

Fig. 146.— Eight astragalus, from below. (G. D. T.)

THE TARSUS.

131

part, between this and the anterior articulation with the os calcis, is a facet which
rests upon the internal calcaneo-navicular ligament, the three forming one con-
tinuous articular surface. The posterior surface is of small extent, and marked at
its inner part by a groove for the flexor longus hallucis, which is continuous below
with that of the sustentaculum tali. Bounding the groove are two tubercles, of
which the internal is usually but little marked, while the external is more prominent
and gives attachment to the posterior band of the external lateral ligament of the
ankle-joint.

The navicular or scaphoid bone is placed at the inner side of the foot
Ijetween the astragalus and the cuneiform bones. It is elongated transversely, and
compressed from before backwards. It presents
posteriorly an articular concavity for the head of
the astragalus, and anteriorlij a convex surface
divided by two lines converging below into three
facets, which articulate respectively with the three
cuneiform bones. Its upper surface is convex
from side to side ; the loiver is narrower and very
uneven. On the outer end there is in some
instances a small articular surface for the cuboid
bone ; the inner end forms the prominent tube-
rosity, directed downwards, and giving insertion
to the tendon of the tibialis posticus muscle.

The cuneiform bones are known as first,
second, and third, from within outwards, or in-
ternal, middle and external. They are placed between the navicular bone and the
inner three metatarsal bones, and present anteriorly and posteriorly smooth surfaces
for articulation with those bones. The internal cuneiform bone is the largest, the

Fig. 147. —Eight navicular bone,

FROM BEFORi:. ((j. D. T. )

Fig. 148. — Right internal cuneiform bune : A. inner vir,\v ; B, outer vrinv. (G. D. T.)

middle is the smallest. The proximal ends of the three bones arc in tLe same trans-
verse line ; but at their distal ends the internal and external project forwards
beyond the middle one, and thus form a deep recess into which the base of the
second m(;tatarsal bone is received.

The internal cuneiform bone has its sliai]) border directed upwards, and
the thick rounded base of the wedge projects downwards on the inner border of
the foot. The anterior articular surface, for the first metatarsal b(Mie, is nmch
larger than the 'posterior, is kidney-shaped and convex. The inlernat surface is
free, rather uneven, and marked by an oblique groove for the tendon of the tibialis
anticus muscle, ending below in an oval facet where the larger part of the tendon is
inserted. On the outer side, along the posterior and supei'ior ])ordeis, is an L-shaped
surface, which articulates with the middle cuneiform, and at its anterior extremity
with the second metatarsal bone.

K 2

132

THE BONES OF THE LOWER LIMB.

The middle cuneiform bone has its base directed upwards, and the sharp
edo-e downwards towards the sole. The posterior end is somewhat broader than the
anterior. On the inner side is an L-shaped articular surface, corresponding to thai

on tlie internal cuneiform bone ; and
on the outer side is a smaller facet, at
the posterior part, for the externaL
cuneiform bone.

The external cnneiform bone is
also situated with its base upwards. At
its anterior end is a triangular articular
surface for the third metatarsal bone,
and continuous with this are small
facets on the fore part of each lateral
surface, for the second and fourth meta-
tarsal bones. On the internal surface, at the posterior part, is an articular facet
for the middle cuneiform bone, and on the outer surface a much larger one for the
cuboid bone.

The cuboid bone is situated on the outer side of the foot, between the

A. B.

MID. CUM.

Fig. 149. — Right middle cukeiform bone :

A, INNER VIEW ; B, OUTER VIEW. (G. D. T. )

Fig. 150. — Right external cuneiporm bone : A, inner view ; B, outer view. (Gt. D. T.)

calcaneum and the fourth and fifth metatarsal bones. It deviates from the cuboid
form and becomes rather pyramidal, by the sloping of four of its surfaces towards
the short, rounded external border. Posteriorly it articulates with the os calcis, and
the lower internal corner projects backwards as a conical process beneath the anterior

B.

□ S CALCIS

TUBEROSITY
CROOVE OF PERONEUS L0IMCU5

OVE OF PER. LONG.
FACET ON TUBEROSITY

Fig. 151. — Right cuboid bone: A, inner view; B, outer view. (Gr. D. T.)

extremity of tliat bone. Its anterior surface, smaller than the posterior, is divided
into an internal quadrilateral and an external triangular facet, articulating with the
fourth and fifth metatarsal bones. On its internal aspect in the middle, and
reaching the superior border, is a surface for articulation with the external cuneiform
bone ; and behind this, in many instances, is a smaller facet articulating with the
navicular, while the remainder is rough for ligaments. The superior surface,
looking upwards and outwards, is on the whole flat, but rather rough. On the
inferior surface is a thick oblique ridge or tuberosity^ the outer end of which

THE METATARSUS.

ia3

presents a smooth facet, covered with cartilage in the recent state, where the tendon
of the peroneus lougus turns round into the sole. Between the tuberosity and the
anterior margin of this surface is a deep groove, beginning at a notch in the outer
border of the bone, for the reception of the tendon. Behind the tuberosity is a
triangular depressed area occupied by the plantar calcaneo-cuboid ligament.

Varieties. — Iiistances are recorded in which the number of tarsal bones is reduced owing
to congenital synostosis of the os calcis and navicular, of the astragalus and os calcis. or of the
asti-agalus and naviciilar. An increase in number may arise from the separation of the
external tubercle at the back of the astragalus (cv fj-if/onuni — Bardeleben), or of the tuberosity
of the navicular bone, from the division of the internal cuneiform bone into dorsal and
plantar pieces, and from the presence of a supernumerary ossicle at the fore and inner part of
the OS calcis. or between the internal cuneiform and second metatarsal bones. (H. Leboucq,
■• De la soudure congenitale de certains os du tarse," Bull, de TAcad. Roy. de Med. de Belgique,
1890. 103 : L. Stieda. '• Der Talus und das Os trigonum Bardelebeus beim Menschen." Anat.
Anzeiger. ISSU, 30.5 : W. Gruber. " Os cuneiforrae I. bipartitum beim Menschen," Mem. Acad.
St. Petersburg. 1 877 ; Hartmann et Mordret. •■ Anatomic du premier cuneiform," Bull. Soc.
Anat. de Paris. 1889, 71.)

THE METATARSUS.

The five metatarsal bones are distinguished by numbers, according to their
position from within outwards. They resemble the metacarpal bones of the hand in
being long bones, slightly convex from end to end on the dorsal aspect, in having
differently shaped bases, three-sided shafts, and rounded heads which articulate
with the phalanges. They also agree with the metacarpal bones in the number of
bones with wliieh ench articulates.

The first metatarsal bone is the shortest, but is much thicker and more
massive than the others. On its base is a large kidney-shaped surfece, slightly

concave, for articulation with the internal cunei-
form bone, and sometimes there occurs a small
facet on the outer side for the second metatarsal
bone. The lower part of the base forms the tube-
rosiiij, which projects downwards and outwards in
the sole, and is marked on its outer side by a
rounded impression for the peroneus longus : on
the inner .side is a smaller mark where a slip of the
tibialis anticus is inserted. Of the three surfaces

SESAMOID BONES

Pig. ]52. — First metatarsal bone op
ri<;ht foot : i'i,a.ntar asi'ect. (G. D. T.)

Fig. 153. — Bases op the mktataksal hones,

FROM BEHIND. (G. D. T.)

of the shaft, the superior, which looks also inwards, is oblong and convex, the
inferior is concave, and tlie externa], the largest, is triangular and flattened. The
head is largo, and has on its under surfiice a median ridge, separating two grooves in
which the sesamoid bones glide.

134

THE BONES OF THE LOWER LIMB.

A.

B.

Fig. 154. — Second, third, and fourth metatarsal bones op the right foot : A, from inner

SIDE ; B, FROM outer SIDE. (G. D. T.)

The remaining four bones are distinguished from
the metacarpal bones by being more slender and
compressed from side to side, corresponding to the
narrower form of the foot compared with that of
the hand. The second is the longest ; the others
diminish gradually to the fifth. Their shafts pre-
sent in the greater part of their extent a prominent border
looking upwards, which in the middle three appears on
the back of the foot between the dorsal interosseous
muscles on each side. Their heads are elongated from
above down, and terminate below in two small projec-
tions ; on each side is a tubercle and depression for the
attachment of the lateral ligament. The lases differ in
the several bones, and thus furnish distinctive cha-
racters between them. The second has a triangular base,
which articulates with the middle cuneiform bone ; on the
inner side is a small facet for the internal cuneiform, and
sometimes, below and in front of this, a less distinct
surface for the first metatarsal bone ; on the outer side
there are usually two small surfaces, an upper and a
lower, each again subdivided into two, thus making four
facets, of which the two posterior articulate with the
external cuneiform, and the two anterior with the next
metatarsal bone. The third has also a triangular base articulating with the external
cuneiform bone ; on the inner side are usually two facets for the second, and on the
outer side a single larger facet for the fourth metatarsal bone. The base of the fourth

TUBEROSITY

Fig. 155. — ^Fifth metatarsal

BONE op right FOOT : DORSAL

ASPECT. (Gr.D.T.)

THE PHALANGES. BOXES UF THE FOOT AS A WHOLE.

135

is oblong or oval, and articulates with the cuboid ; on the inner side is generally a
double facet for the third metatarsal and the external cuneiform bones, but the arti-
culation with the latter is sometimes absent : and on the outer side is a single surfoce
for the fifth metatarsal bone, with a deep groove below it. The fifth articulates by
its base with the cuboid, and internally with the fourth metatarsal bone, while
externally it projects in a large rough tuherosihj, into which the peroneus brevis
muscle is inserted.

Variety.— In some rare cases an independent ossicle has been found taking- the place of
the tuberosity of the fifth metatarsal bone (W. Gruber, Virchow's Archiv, xcix, 460 ; Ch.
Debierre, Bull. Soc. Anat. de Paris, 1888, 3<J2).

THE PHALANGES.

The phalanges of the toes correspond so nearly in general conformation with
those of the fingers that it will only be necessary in this place to state the points in
which they difler from the latter.

The phalanges of the four outer toes are much smaller than the corresponding pha-
langes of the hand ; but those of the great toe are larger than those of the thumb.
The shats of the first row of phalanges in the four outer toes are
compressed laterally and narrowed in the middle ; those of the
second row, more especially in the fourth and fifth toes, are very
short, their length scarcely exceeding their breadth. The last two
phalanges of the little toe are frequently connected by bone into
one piece.'

Sesamoid boxes. — Two sesamoid bones, developed in the
tendons of the flexor brevis hallucis, lie side by side in the
plantar wall of the first metatarso-phalangeal joint, and glide in
the grooves on the head of the first metatarsal bone. Small
sesamoid bones sometimes occur in the corresponding joints of
the other toes.

THE BONES OP THE FOOT AS A WHOLE.

The foot is narrowest at the heel, and as it passes forward
becomes broader as far as the heads of the metatarsal bones.
The posterior extremity of the calcaneum is inclined slightly
inwards. The astragalus, overhanging the sustentaculum tail,
inclines inwards from the calcaneum so much that its external
superior border is directly over the middle line of the calcaneum?
and hence the internal malleolus appears more prominent than the
external. The foot is arched from behind forwards, the posterior pier of the arch being
formed by the heel, the anterior by the heads of the metatarsal bones. The arch,
indeed, may be considered as double in front, with a common support behind. The
internal division of the arch is that which bears the greater part of the weight of
the body, and is most raised from the ground ; it consists of the posterior two-thirds
of the calcaneum, the navicular and cuneiform bones, and the three inner metatarsal
bones ; the outer arch is formed by the calcaneum in its whole length, the cuboid
bone, and the fourth and fifth metatarsal bones. Besides being arched longitudinally,
the foot presents likewise a transverse arch, formed behind by the cuboid and three
cuneiform bones, and in front by the metatarsal bones.

Fig. l;-)*;. — Pha-
langes OF S?;COND
TOE : PLANTAR
ASPECT. (G.D.T.)

' W. Pfitzner found thi.s union in about 36 jjer cent., and as frequently in infants
Ardi. f. Anat., 1890, 12).

as in adults

:36

THE BONES OF THE LOWER LIMB.

OSSIFICATION OF THE BONES OF THE LOWER LIMB.

Hip-bone. — The hip-bone is formed from the three principal pieces previously mentioned,
viz., the ilium, ischium, and os pubis, and from various others of an epiphysial nature. Ossifi-
cation commences in the cartilage of the ilium a little later than in other large bones, the
deposit of bone beginning above the ilio-sciatic notch in the 8th or 9th week. This is followed

Fig. 157. — Ossification op the hip- bonk. (R. Quain.)

A, the condition of the bone at birth. Bone has spread from three nuclei into the ilium, ischium,
and pubis, which meet in the cartilage of the acetabulum.

B, from a child under six years of age. The rami of the ischium and pubis are farther ossified, but
still separate.

C, a bone of two or three years later, in which the rami are united.

D, the bone of the right side from a persoQ of about twenty years. Union has taken place in the
acetabulum, and the additional epiphyses are seen on the crest of the ilium, the anterior inferior spine,
the ischial tuberosity, and the margin of the symphysis jDubis.

In A, B, and C, 1, ilium ; 2, ischium ; 3, pubis ; in D, 5, epiphysis of the crest ; 6, that of the tube-
rosity of the ischium ; 7, that of the symphysis pubis ; 8, that of tlie anterior inferior spine of the ilium.

by similar deposits in the thick part of the ischium below the acetabulum in the 3rd month,
and in the superior ramus of the pubis in the 4th or .5th month. At birth the greater part of
the acetabulum, the crest of the ilium, the tuberosity and ramus of the ischium, the body and
inferior ramus of the pubis are still cartilaginous ; ossification from the three primary centres
lias however extended into the margin of the acetabulum. In the 7th or 8th year the rami of

Fi£

158. — Acetabular region of the hip-bone

AT 14 TEAKS of AGE. (G. D. T.) ^

1, ilium; 2, ischium; 3, pubis; 4, os acetabuli ;
5, bony nodules between ilium and ischium ; 6 and
7, epiphysial laminje on ilium and ischium.

the ischium and pubis become completely united
by bone. In the acetabulum the three parts are
still separated by a Y-shaped strip of cartilage,
which is continuous with that lining the cavity.
This cartilage begins to be ossified from several
centres about the 12th year. The most constant of
these gives rise to a triangular piece of bone at the
fore part of the acetabulum, which is known as
the OS accfnhuli} and forms the whole of the so-
called pubic portion of the articular cavity. It
becomes united first with the pubis, and later with
the ilium and ischium. Between the ilium and
ischium there are only some irregular nodules of bone, and other small osseous points form a
more or less perfect lamina over the iliac and ischial portions of the articular surface. The
union of the several portions in the acetabulum is completed from the 18th to the 20th year.

1 W. Leche. Internat, Monatschr, f. Anat. u, Histol,, 1884, 363 ; W, Krause, ih., 1885, 150.

OSSIFICATIOX OF THE BOXES OF THE LOWER LIMB.

137

Epiphyses are likewise formed in the cartilatre of the crest of the ilium, the tuberosity of the
ischium, the anterior inferior spine of the ilium, and the symphysis pubis. These begin to
ossify soon after puberty, and unite with the main bone from the 23rd to the 2oth year.

The 2)clr;.-< of the foetus and young child is of very small capacity in proportion to the size
of the body, and those viscera which are afterwards contained for the most part in the true

Fig. 159. — Ossification of the femur. (R. Quaiii.)

A from a fcetus under eight months ; the body is osseous, both ends are curtilagiuous.

B, from a child at birth, showing a nucleus in the lower epiphysis.

C, from a child of about a year old, showing a nucleus in the head.

D, at the fifth year ; a nucleus has appeared in the great ttocliaiiter.

E, near the age of puberty, showing a nucleus in the lesser trochanter.

1, shaft ; 2, lower extremity ; 3, head ; 4, great trochanter : .'>. small trochanter.
C, D. & E are represented considerably, A & B very little, under the natural size.

Fig. 160.— Ossification op the tibia. (R. Quuin.)

A. some weeks before birth ; the shaft is ossified, the ends are cartilaginous.

B, at birth, showing a nucleus in the upper epiphysi.s.

C. at the third year, showing tlie nucleus of the lower epiphysis.

D, at about eighteen or twenty years, showing the lower epiphysis united, while the upper remains
aej^arate. The upper epiphysis is seen to inclmli; the tubercle.

K. shows an example of a septvrate centre for the tubeicle.

1, shaft ; 2, superior epiphysis ; 2*, separate centre for the tubercle ; 3, inferior epiphysis.

pelvis occupy a part of the abdominal cavity. The inclination of tlio pelvis i.s considerably
greater in early life than in the arlult.

The femur is developed from one principal ossific centre for the shaft which appears in the

188

THE BONE.S OF THE LOWER LIMB.

7th week, and from four epiphj^ses, the centres for which appear in the following order : — A
single nucleus for the lower extremity appears shortly before birth, one for the head appears
in the 1st year, one for the great trochanter in the 4th year, and one for the small trochanter
in the 13th or 11th year. These epiphyses become united to the shaft in an order the reverse
of that of their appearance. The small trochanter is united about the 17th year, the great
trochanter about the 18th year, the head from the ISth to the 19th year, and the lower ex-
tremity soon after the 20th year. The neck of the femur is formed by extension of ossification
from the shaft.

The patella is formed in the 3rd month by a deposit of cartilage in the tendon of the
quadriceps extensor cruris muscle. In this cartilage ossification begins from a single centre
during the 3rd year, and is completed about the age of puberty.

Fig. 161. — Ossification of the fibula. (R. Quain.)

A, at biftli ; the shaft is ossified, the ends are cartilaginous.

B, at two years, showing a nucleus in the lower epiphysis.

C, at about four years, showing tlie nucleus of the upper epiphysis ; the lower ought to have been
shown as more advanced.

D, at about twenty years ; the lower end is complete, but the upper epiphysis is still separate.
1, shaft ; 2, lower epiphysis ; 3, ui^per epiphysis.

The tibia and fibula each present, besides the principal centre for the shaft, a superior
and an inferior epiphysis. In the tibia the centre for the shaft appears in the 7th week ; that
for the upper extremity, including both tuberosities and the tubercle, appears most frequently
before, but sometimes after birth ; and that for the inferior extremity and internal malleolus
appears in the 2nd year. The tubercle is occasionally formed from a separate centre. The
lower epiphysis and shaft unite in the ISth or 19th year, the upper epiphysis and shaft in the
21st or 22nd year. In the fibula the centre for the shaft appears rather later than in the tibia ;
that for the lower extremity appears in the 2nd year, and that for the upper, unlike that of the
tibia, not till the 3rd or 4th year. The lower epiphysis and shaft unite about the 21st year,
the upper epiphysis and shaft about the 21:th year.

The fibula in the embryo at an early period is nearly as large as the tibia, and also articu-
lates with, the femur. The tibial malleolus on the other hand is up to the seventh month of
foetal life longer than the fibular ; and the marked preponderance of the fibular malleolus,
which is peculiar to man, is only acquired after birth (G-egenbaur).

The tarsal bones are ossified in cartilage each from a single nucleus, with the exception of
the OS calcis, which in addition to its proper osseous centre, has an epiphysis upon its posterior
extremity. The principal nucleus of the os calcis appears in the 6th month of foetal life ; its
epiphysis begins to be ossified in the 10th year, and is united to the tuberosity in the loth or
16th year. The nucleus of the astragalus appears in the 7th month ; that of the cuboid about
the time of birth ; that of the external cuneiform in the 1st year ; that of the internal cunei-
form in the 3rd year ; that of the middle cuneiform in the 4th year : and that of the navicular
in the 4th or 5th year.

The metatarsal bones and phalanges agree respectively with the corresponding bones of
the hand in the mode of their ossification. Each bone is formed from a principal piece and
one epiphysis ; and while in the f oiu- outer metatarsal bones the epiphysis is at the distal ex-

OSSIFICATIOX OF THE BOXES OF THE FOOT.

139

tremity. in the metatarsal bone of the great toe and in the phalannres it is placed at the
proximal extremity. In the first metatarsal bone there is frequently, as in the first metacarpal
(see p. 109). also a second or distal epiphysis ; and in some instances a proximal epiphysis is
formed on the tuberosity of the fifth metatarsal bone (Gruber). In the metatarsal bones the

Fig. 162.— Ossification of the bones of the foot. (R. Quain. )

A, right foot of a foetus of six months ; the metatarsal bones and digital phalanges have each their
shafts ossified from their primary centres ; the tarsus is wholly cartilaginous, excepting the os calcis,
in which the nucleus of bone has just appeared.

B, foot of a fretus of seven or eiglit months ; the astragalus shows a nucleus.

C, from a child at birth ; the cuboid has begun to ossify.

D, about a year ohl, showing a nucleus in the external cuneiform.

E, in the third year ; ossification has reached the iiiternal cuneiform.

F, about four years old, showing ossificalion in the middle cuneiform and navicular bones, and in tlie
ejiiphyses of the metatarsal bones and phalanges.

G, about the age of puberty ; ossification is nearly complete in the tars.al bones ; an epipliysis has
been formed on the tuberosity of the os calcis, and the epiphyses of the metatarsal bones and phalanges
are shown separate.

], nucleus of tlie os calcis ; 1* in G, the epiphysis of the os calcis ; 2, nucleus of the astragalus ; 3, of
the cuboid ; 4, of the external cuneiform ; 5, of the internal cuneiform ; 6, of the navicular ; 7, of tlie
middle cuneiform ; S, metatarsal bones ; 8*, distal epiphysis of the .second metatarsal bone ; H', proximal
epiphysis of the first ; 9, first phalanx of the second toe ; 9*, proximal epiphysis of this phalanx ; 9'.
that of the first jjhalanx of the great toe ; 10, .second phalanx ; 10*, the epiphysis of this phalanx ;
10', epiphysis of the terminal phalanx of the great toe ; 11, terminal phalanx ; 11*, its epipliysis.

nuclei of the .shafts appear in the Sth or 9th week. The epiphyses aiipcai- from the 3rd to the
8th year, and unite witli the shafts from the 18th to the 'JOth year. Tlie nuclei of the shafts
of the phalantres apiKiar in the 9th or 10th week. The epiphyses appear from the Ith to the
8th year, and unite with the Bhafte from the 19th to the 21st year.

140 MOKPHOLOGY OF THE iiONES OF THE LIMBS.

In the infant the head of the astragalus is directed more inwards than in the adult, and
the foot is naturally inverted. The first metatarsal bone is also relatively short in the foetus,
and at first is inclined inwards from the internal cuneiform bone, the distal articular surface
of which is oblique. In these respects the young foot is more like that of the ape. (Leboucq,
" Le developpement du premier metatarsien et de son articulation tarsienne chez I'homme,"
Arch, de Biologie, iii, 33.5.)

MOKPHOLOGY OF THE BONES OF THE LIMBS.

Relation to the axial skeleton. — Anatomists have generally agreed to look upon the relation
which the bones of the limbs bear to the rest of the skeleton as that of appendages to the
trunk, and most are also disposed to regard these appendages as similar radiations or extensions
from one or more of the vertebral segments in two determinate situations of the trunk. But
opinions are much divided as to the typical number of the vertebral segments which are in-
volved, and as to the exact moi-phological nature of the parts Avhich form the radiations. The
quinquifid division of the peripheral parts of both limbs in man and many animals appears
favourable to the view that each has the elements of five segments prolonged into it ; but of
late years attention has been specially dii-ected by K. Bardeleben and others to certain mar-
ginal structures which are interpreted as vestiges of more or less completely suppressed digits,
and there seems reason for believing that the pentadactyle extremity has been preceded by a
heptadactyle form. In association with this it may be noticed also that the nerves entering
into the proper limb-plexuses are in each case seven, viz., the 4th, 5th, 6th, 7th and 8th
cervical, with the 1st and 2nd dorsal, in the brachial plexus, and the 2nd, 3rd, 4th and 5th
lumbar, with the 1st, 2nd and 3rd sacral in the crural plexus. It is farther generally held
that the constituent elements follow each other in a similar order in the two limbs from the
cephalic to the caudal part of the vertebral axis, so that the poUex and radial elements occupy
the cephalic side of the upper, while the hallux and tibia take the same place in the lower
limb.

Homolog'ical comparison of upper and lower limbs. — A certain anatomical correspond-
ence between the upper and lower limbs, which is apparent to common observation, is
admitted in even a fuller degree by most anatomists as a result of a careful comparison of the
form and relations of their bones, as well as of their other parts, in both their embryonic and
fully formed conditions ; and the general conclusion has been formed that the thoracic and
pelvic limbs are constructed on the same general type in man and animals, both as regards
the attaching girdles of the shoulder and pelvis, and in the three several sections of which
each limb is composed. There are, however, certain modifications of that general plan,
leading to considerable differences in the form, size, and number of the individual parts in
different animals, which appear to be in a great measure related to the different uses to which
the upper and lower limbs are respectively applied ; as, for example, in the upper limb of
man, the breadth of the shoulders, caused by the interposition of the clavicle, the greater
extent of motion in the shoulder- joint, the eversion of the humems, and the forward flexed
attitude of the elbow-joint, the arrangements for pronation and supination by rotation of the
radius and hand, and the opposability of the thumb, aU have reference to the freedom,
Versatility, and precision of the movements of the upper limb as an organ of prehension and
iouch ; while in the lower limb, the comparatively fixed condition and arched form of the
pelvic girdle, the greater strength of the bones, the close-fitting of the hip-joint, the inversion
of the femur, the backward flexure of the knee-joint, the arched form of the foot, and non-
opposability of the great toe, have all manifest relation to the support of the trunk and
pelvis, and their movements upon the lower limbs. In the lower animals, greater modifica-
tions in the form of both limbs are to be observed, obviously adapted to their different
functions in each case.

Without attempting to follow out this subject by any detailed reference to comparative
anatomy or development, it may be useful to state here shortly the more probable conclusions
w^hich have been formed with respect to the homological correspondence of the several parts
of the upper and lower limbs.

Shoulder and pelvic girdles. — In each of these a division is to be recognized at the place
of attachment of the limb-stalk (shoulder and hip-joints) into a dorsal and a ventral section.
The dorsal section in the upper limb is the scapula, in the lower limb the ilium, which
accordingly correspond, the chief difference between them consisting in the scapula being
free from articulation with the vertebral column, and therefore capable of a considerable
degree of motion, while the ilium is firmly jointed to the lateral mass of the sacrum. The
ventral section is in each case double, including the clavicle and coracoid in the shoulder-
girdle, and the pubis and ischium in the pelvic girdle. It is generally admitted that the
coracoid and ischium are corresponding structures, the coracoid being reduced to a relatively

THE SHOULDER AND PELVIC GIRDLES.

141

small process in man and most mammals, but forming a large and important bone which
reaches the sternum in monotremata and many lower vertebrates. The pubis appears to be
represented most closely by the precoracoid of reptiles and amphibia, while the clavicle is not

Figs. 163 & 164. — Sketch of the

BONES OF THE THORACIC AND
PELVIC LIMBS, so PLACED AS TO
SHOW CORKESPONDINO PARTS IN

BOTH. (Allen Thomson. )

The preaxial borders of both hiubs
are towards the reader's right hand,
and the original dorsal or e.xtensor sur-
faces are shown throughouttheir whole
e.xtent. The somewhat artificial re-
presentation given in these figures
cannot be obtained from a single
view of the specimens in one posi-
tion, but it is easily brought out bv
slightly shifting the bones or changing
the point of view. The humeral
tuberosities are separated so as to
show them on the borders of the
bone. Fig. 163. Thoracic limb ;
ss]}, supraspinous or prescapular fossa;
isp, infraspinous or postscapular
fossa ; ssc, a small part of the subsca-
pular fossa ; ^x, base of scapula ; sa,
superior angle ; ia. interior angle ;
sp, spine ; nc, acromion ; cr, coracoid
process ; gb, glenoid border with place
of attachment of triceps muscle ; ffr,
glenoid cavity ; h, humerus, preaxial
border ; tm, large or preaxial tube-
rosity ; t]), small or po.staxial tube-
rosity ; cr, radial condyle ; cit, ulnar
condyle ; r, radius ; it, idna ; o,
olecranon ; ^w, poUex and preaxial
side ; pi, pisiform and postaxial .side
of hand. Fig. 164. Pelvic limb ;
ss, sacral surface of ilium ; il, iliac
fossa ; di. a small part of the dorsum ilii
or gluteal surface ; ic, crest of ilium ;
as, anterior superior spine ; ipl,
ilio-pectineal line ; c]). ilio-pectineal
eminence ; is. anterior inferior spine
and attachment of rectus muscle ; cc.
cotyloid cavity ; sp. symphysis pubis ;
isc, ischium ; /. femur, its preaxial
border ; trp. lesser or preaxial tro-
chanter ; tnn. greater or postaxial
trochanter ; ci, tibial condj'le ; if,
fibular condyle ; ^;, patella ; t. tibia ;
tt. tubercle of tibia ; //. fibula ;
hx, hallux and preaxial side of foot ;
ca, calcaneal tuberosity.

repeated in the pelvic girdle ; it
is. however, held by many anato-
mists that the mammalian clavicle
corresponds morphologically to the
reptilian precoracoid. and there-
fore iH also the representative of
the pubiH.

With regard to the comparison to be establi.sned between the individual })arts of the
scapula and ilium there is much difference of opinion, but an examination of the simpler
forms of thewe bones in some of th(! lowfM- animals, and a general consideration of their
relations give support to the view adopted by Flower as the more probable.' The scapula and

' Flower, Joum. Anat., iv. and "Osteology of the Alainnjalia." For diflercnt views, see Humphry^

142

MORPHOLOGY OF THE BONES OF THE LIMBS.

ilium may be regarded as consisting essentially of three-sided prismatic rods, in the primitive
position of which an internal or vertebral surface is separated from tvi^o external surfaces by
preaxial and postaxial ridges, and the two external surfaces are separated by an external
ridge, which descends from the dorsal extremity of the bone to the joint-socket. It is
on this external ridge, (jlcnoid in the scapula and cotyloid in the ilium, that in each case
the long head of the great extensor muscle of the limb is attached. The primitive arrange-
ment is modified in two ways, viz., 1st, by the outgrowth to a greater or less extent of the
edges of the rod, thus giving rise to f ossfe in the situation of the original surfaces, and 2nd,
by the occurrence of a rotation in different directions in the two limbs, the scapula outwards.

Fig. 165. — Diagram of an early human

EMBRYO, SHOWING THE RUDIMENTARY
LIMBS IN THEIR SECOND POSITION. (Allen

Thomson. )

r, preaxial or radial and iDollex border of
the thoracic limb ; u, its postaxial or ulnar
and little finger border ; t, preaxial or
tibial and hallux border of the pelvic limb ;
./', its postaxial or ribular and little toe
border.

the ilium inwards, in accordance with the rotation Avhich takes place during the course of
development in the free part of the limb. The primitive vertebral sui-face of the scapula
becomes the prescapular or supraspinous fossa, while in the ilium the corresponding surface
is the sacral, which, being connected to the vertebral column, undergoes but little change in
position. The postscapular or infraspinous fossa of the scapula is accordingly represented by
the iliac fossa of the ilium, and the subscapular fossa by the gluteal surface. (See the table
of homologous parts below.)

Bones of the limbs. — In making the comparison of the bones composing the limbs them-
selves, it is necessary to revert to the simpler relations subsisting between the limbs and the
trunk or vertebral axis of the body in embryonic life. In the earliest stage the limbs may be
said to bud out from the side of the trunk as flatfish semilunar flaps, so that they present a

Fiff. 166.-

-DORSAL SURFACE OF THE RIGHT MANUS OF A WATER

TORTOISE. (Gegenbaur.)

R, radius ; U. ulna ; )•. radiale ; i, intermedium ; te.ulnare ; r.centrale ;
1 — 5, five carpal bones of the distal row ; ni' — 711", five metacarpals.

dorsal and a ventral siu-face. coinciding with these respective
surfaces of the trunk ; but in the next stage, when the limbs
come to be folded against the body in the ventral direction,
although the original relation to the trunk is undisturbed,
their axes have now come to lie nearly perpendicularly to the
coronal plane of the vertebral axis, and the position of the limbs
is such that in each there is one border which looks towards
the head, and another which looks towards the tail. To these
borders of the limbs the names of preaxial and postaxial are
given respectively, as indicating their position before and
behind the limb-axis. When at a somewhat later stage of
development the divisions of the limbs make their appearance,
and more especially when the quinquifid division of the digits
in the hand and foot becomes perceptible, it is obvious that the thumb and radius in the one
limb, and the great toe and tibia in the other, occupy corresponding cephalic and preaxial
situations ; and it is not difficult to trace from these the corresponding relations of the parts
in the upper division of the limbs. Thus, the radial condyle of the humerus with the great
tuberosity are preaxial, while the lesser tuberosity, ulnar condyle, ulna, and little finger are
postaxial. In the lower limb, the small trochanter, internal condyle, tibia and great toe are
preaxial, while the great trochanter, external condyle, fibula, and little toe, are postaxial.
And at the same time the dorsal or extensor surface of the limbs is external, and the ventral
or flexor surface is internal.

Joiirn. Anat., v, 67 ; Sabatier, ' ' Comparaison des ceintures et des membres anterieurs et posterieurs
dans la serie des vertebras," Montpellier, 1880.

COMPARISOX OF THE HAND AND FOOT.

143

Very soon, however, in the hig'her animals and in man, farther changes operate in bringin^r
about the permanent condition. The humerus is folded backwards against the trunk, and at
the same time undergoes a rotation outwards, so that the radial (preaxial) condyle becomes
external, and the extensor aspect of the elbow is directed backwards. The femur, on the
other hand, is inclined forwards and rotated inwards, thereby bringing the tibial (preaxial)
condyle to the inner side, and the extensor aspect of the knee forwards. The rotation of the
humerus outwards in man amounts to about 4.5". so that the axis of the elbow-joint is placed
obliquely to the median plane, but in quadrupeds the rotation takes place through 90"^. and thus
the axis of the elbow-joint becomes transverse. The rotation inwards of the femur is about 1)0°,
and the axis of the knee-joint is therefore placed transversely, in both man and quadrupeds.
In the upper limb of man. the radius being in semiprouation. no material change occurs in
the position of the hand, the thumb hanging naturally forwards ; but in animals destined to
rest on the palmar aspect of the hand or digits, important changes occur in the position of the
radius by which, as this bone is brought forwards upon the humerus, and its lower end carried
inwards, the manus or its elements are placed permanently in the prone position, with the

Fig. 167. — Dorsal surface of the right
CARPUS OF MAX. (Flowcr. )

.1. scaphoid ; /. huiar ; c. cuneiform or pyra-
midal ; p, pisiform ; tm. trapezium ; td, tra-
pezoid ; VI. magnum ; u, unciform ; I — V, five
metacarpals.

Fig. IfiR. — Dorsal surface op the carpus
OF A BARooN. (Flower. j

.s\ scaplioid ; /. lunar ; r. cuneiform or pyra-
midal ; ^), pisiform ; tm, trapezium ; td. trape-
zoid ; m. magnum ; n, imciform ; rs. i-adial sesa-
moid ; cr. OS centrale ; I — V, five metacarpals.

first or radial digit inwards. In the foot no such change is required, as already by the internal
rotation of the femur at its upper part, the conditions for plantar support have been secured,
and the first or tibial digit is on the inner side. Farther, in man. as the body attains its full
development, both limbs are extended in a line parallel to the axis of the ti'unk. the upper
dropping loosely from the shoulder- joint with the greatest freedom of motion ; the lower more
closely articulated in the hip-joint, and suited to give firm support to the body in the erect
posture.

Hand and foot. — The similarity of the digital and metacai-jial bones of the hand
with those of the foot in number, form, and connections is so great that the homodynamous
coiTespondence of these bones is immediately recognised. The main differences between them
consist in the greater length of the fingers, and the opposability of the thumb to the
other digits through its mobility at the carpo-metacarpal articulation, in adajitation to the
function of the hand as a grasping organ.

The morphological construction of the carpus and tarsus is only to be understood by
reference to a more generalized form, such as is met with in the carpus of the water-tortoise
(fig. 100) and in the tarsus of certain amphibia. Here nine elements are seen, arranged in a
proximal series of three, which are named respectively radit/Jr or fihidlc. intrrmcd'ium. and
vinarr ox lihuhtrr, a distal series of five, named ritrpdlUi or tarmVia I — V. counting from the
preaxial border, and an interposed rrntralr} In man. as in nearly all mammals, the distal
row of the carpus and tarsus comprises only four bones, the unciform and cuboid, which
support the postaxial two digits, being generally regarded as formed by the fusion of the
fourth and fifth elements. Of the proximal elements of the carpus, the radiale is represented
in the scaphoid, the intermedium in the lunar, and the ulnare in the pyi-amidal. The centrale
appears to be ab.sent in the carpus of man. although it occurs as a distinct bone in nearly all
apes. In the human fVjctus, however, at the latter part of the second month, a I'udiment of
the centrale is present as a small cartilaginous nodule, which in the course of the third month
becomes fused with the cartilage of the scaphoid." The latter bone must therefore be regarded

' ficgenbaur. " Unt^^rsuch. zur vergleich. Anat. ; I. Carpus und Tarsus," Lcijizig, 18G4.
- Lcboucq, " Ilccherches sur la morphologic du carpe chez lea mammifc'res," Arch, de Biologie,
V, 3.V

144

MORPHOLOGY OF THE BONES OF THE LIMBS.

as composed of tlie radiale and the centrale. Traces of the central e are often to be recognized
in the adult scaphoid, and it may in rare cases be developed as a separate bone. In the
proximal series of the tarsus the course of development is somewhat different. The astragalun
results from the union of the tibiale and intermedium, although the latter occasionally
remains distinct as the os trigonum (p. 133) : at the back of the posterior articular surface on
the under aspect of the astragalus there is often to be seen a slight groove, indicative of this
separation (fig. 146). The fibulare forms the greater part of the os calcis, and the centrale of
the navicular bone. The pisiform bone has been considered a sesamoid bone (uhiare sesMiioi-
deuiii) developed in the tendon of the flexor carpi ulnaris, but recent investigations tend to
show that it is a vestige of a suppressed ray (digitus postminimus) : the coi-responding
structure of the tarsus enters into tuberosity of the os calcis. On the outer margin of the
carpus there is in some animals another bone (radiale sesamoideiim'), which, if represented in
man, seems most nearly to correspond to the tuberosity of the scaphoid ; and the tuberosity of
the navicular bone of the tarsus may be the representative of a similar element (tibiale
sesamoidewtn) in the foot. These so-called " sesamoid " ossifications are also regarded by
Bardeleben as vestiges of a suppressed digit (prepoUex or prehallux).i

The following tables present a synoptical view of the probable corresponding or homolo-
gous bones and their parts in the thoracic and pelvic limbs : —

I. — Table op the Homologous Bones in the Thokacic and Pelvic Limbs.

Thoracic Limb.

Scapula .....

Precoracoid ....
Coracoid .....

Glenoid cavity ....
Clavicle .....
Humerus ......

Great tuberosity .

Small tuberosity

External condyle and capitellum

Internal condyle and trochlea .
Absent .....
Radius ......

Ulna

Carpus ......

Metacarpus .....

PoUex

Digital phalanges

Pelvic Limb.

Hium.
Pubis.
Ischium.

. Cotyloid cavity.
Absent.
Femur.

. Small trochanter.

. Great trochanter.

. Internal condyle.

. External condyle.
Patella.
Tibia.
Fibula.
Tarsus.
Metatarsus.
Hallux.
Digital phalanges.

n. Table or the Homologous Bones of the Carpus and Tarsus.

Carpus.

Pyramidal
Pisiform .
Lunar .

Scaphoid

Trapezium
Trapezoid
Magnum

Unciform

Tt/jncal names.

Ulnare . . . Fibulare .

Ulnare sesamoideum (?) Fibulare sesamoideum (?)

Intermedium Intermedium .

Radiale Tibiale

Radiale sesamoideum (?) Tibiale sesamoideum (?)

Centrale Centrale

Carpale I. Tarsale I. .

il n. . .

III. III.

IV. IV. .

Tarsus.
Os calcis.
Astragalus.

Navicular.

Int. Cuneiform.
Mid. Cuneiform.
Ext. Cuneiform.

Cuboid.

1 According to another view, whicli is supported by Baur and Leboucq, the " tibial sesamoid " is the
tibiale, and the astragalus the intermedium only.

ADAPTATION OF SKELETON TO ERECT ATTITUDE.

145

III. — Table of the Homologous Parts of the Scapula and Ilium (according

TO Flower).

Scapula.

Supraspinous fossa . . .
Infraspinous fossa
Subscapular fossa . . .
Spine and acromion
Superior or coracoid border.
Axillary or glenoid border .

Base

Superior angle . . .

Inferior angle

Primitive condition.

Vertebral surface
Preaxial surface .
Postaxial surface .
Preaxial border .
Postaxial border
External border .
Dorsal extremity .

Ilium.

Sacral surface.
Iliac fossa.
Gluteal surface.
Ilio-pectineal line.
Posterior or ischial border.
Anterior or cotyloid boider.
Iliac crest.

Posterior superior spine.
Anterior superior spine.

ADAPTATION OF THE SKELETON TO THE EREOT ATTITUDE.

The axial skeleton of man is, for the purposes of station and progression, raised more fully to
the vertical position than is the case in any other animal ; and along with this the lower limbi
are extended in lines parallel to the axis of the trunk. The feet rest on the ground by the
contact of the heel and the heads of the metatarsal bones, the centre of gravity of the body
falling within the basis of support. For the maintenance of this attitude, the constant action
of the muscles passing over the ankle-joint is more immediately necessary. But at the knee-
and hip-joints it is mainly by the mechanism of the ligaments and other parts of the joints, and
less directly by muscular action, that the erect attitude is maintained, as will be more fully
shown in the description of the different articulations.

There are, besides, many peculiarities in the construction of the body, and especially of
the skeleton, which are associated with the assumption of the erect posture, and although
many of them have been noticed in the description of the bones, it may still be useful to
recapitulate the chief ones briefly in this place.

It may first be remarked that the full development of these peculiarities belongs to the
adult condition. In the infant, while still unable to walk, the large proportional size of the
head, amounting to nearly a fifth of the whole body, the comparative straightness of the ver-
tebral column, or absence of the curves which characterise the spine of the adult, the short-
ness of the lower limbs, and incompleteness of their structure, all contribute to render the
assumption of the erect attitude by the child, for a time, difficult and insecure. Thus the
middle distance between the vertex of the head and the sole of the foot in an infant is situated
somewhat above the umbilicus, while in the adult it is generally at the upper border of the
pubis, or even lower, in some part of the symphysis. In the child also, from the large dimen-
sions of the head and upper part of the body, the centre of giavity is carried to a considerably
higher point than in the adult.

The skull of man differs from that of other animals in being nearly balanced on the vertebral
column, the condyles of the occipital bone being brought forwards to near the middle of the
base by the comparative shortness of that part of the skull ^\■hich lies in front of the foramen
magnum, and the projection backwards of that which lies behind it. In quadrupeds the skull
extends forwards from the extremity of the column, and is sustained by the elastic ligamentun:
nuchje, represented in man by a comparatively feeble structure which passes between the ex-
ternal occipital protuberance, and the spinous processes of the cervical vertebras. Together
with this altered relation of the head to the spine, the plane of the foramen magnum, which
in quadrupeds is vertical, becomes in man horizontal, or even inclined somewhat upwards
anteriorly.

The spinal column, by its pyramidal form, is fitted to sustain the weight which bears down
upon its lower part, and by means of its different curvatures possesses elasticity and strengtli
combined, and allows considerable range of motion to the trunk, without removal of the centre
of gravity from within its base. The strong and expanded sacrum is the immediate means of
transferring the weight of the trunk to the hip-bones and lower limbs.

The thorax in man is comparatively short, compressed in the sagittal direction, and ex-
panded transversely, whereby the centre of gravity is carried backwards, nearer to the spine.

The pelvis is of peculiar breadth in man, presenting an upper and a lower arch which meet
at the hip-joints, and is so inclined that a vertical line descending from the centre of gravity
of the bo<Jy is in a plane slightly behind the centres of motion of the hip-joints. The breadth
of the pelvis enables the balance to be more easily maintained in lateral movements of tlir
body by compensating inclinations of different paits to opposite sides of the basis of support
and the long neck of the femur gives an advantageous insertion to the muscles by wliicii the

l

146 ADAPTATION OP SKELETON TO ERECT ATTITUDE.

balance of the body is principally preserved. The hip-bone is mainly distinguished from the
same bone in animals by the breadth of its iliac portion, which gives support to the abdominal
viscera, and attachment to the greatly developed iliac and gluteal muscles.

The lower limbs are remarkable for their length and strength. The femur is greatly
elongated, its length considerably exceeding that of the tibia, — a condition which is requisite
not only to give a sufficient extent of stride, but also to enable the body to be balanced in dif-
ferent degrees and varieties of stooping. The foot of man alone among animals has an arched
instep, and it likewise presents a great breadth of sole. The great toe is distinguished by its
full development, and especially from that of the apes, by its want of opposability,
being constructed, not for grasping, but for supporting the weight of the body, and giving
spring to the step.

"While stability and strength are thus provided in the lower limbs, mobility and lightness
are secured in the upper. This is apparent on comparison of the shoulder, elbow, and wrist,
with the hip, knee, and ankle. In the hand, also, the freely moveable phalanges are as long
as the carpal and metacarpal bones taken together, while in the foot they are not a third of
the length of the tarsal and metatarsal bones.

ARTHEOLOGY.

By G. D. THANE.
THE ARTICULATIONS IN GENERAL.

Various forms of joints. — The name of articulation, synonymous with joint,
is given in descriptive anatomy to the connection subsisting in the recent skeleton
between any of its denser component parts, whether bones or cartilages. In all in-
stances some softer substance intervenes between the bones, uniting them together,
or clothing the surfaces which are opposed ; but the manner in which the several
pieces of the skeleton are thus connected varies to a great degree, both as to the nature
of the uniting substances, and the extent of movement which they allow. In some
instances, as in the cranial bones, the closeness of the apposition, the unevenness of the
fitting surfaces or edges, and the small amount and dense nature of the intervening
substance admit of no perceptible movement. In other instances of continuous union
the extremities of the bones are placed at such a distance, and the intervening
substance is so yielding, that bending or other movements may take place. But in
the greater number of articulations the opposed surfaces of bone are not united with
each other, but are free, and are covered with plates of smooth cartilage, the
surfaces of which fit more or less accurately together, while the bones are held
together by ligamentous structures placed in the vicinity of the joint. In such
articulations the bones are capable of gliding or moving upon each other, the extent
and, directions of the movements varying with the shape of the opposed cartilaginous
surfaces, and the form and attachments of the ligamentous and other bands which
unite them. According to differences of the kind now adverted to the various
articulations of the body are classified as follows : —

A. Synarthrosis or continuous articulation. — The adjacent osseous
surfaces are directly united by some interposed substance.

1. Synchondrosis. — A thin layer of cartilage is interposed between the bones, to
which it adheres closely on each side. This articulation is essentially of a transitory
nature, beino- usually converted into bony union {si/nos-

/0676-j before adult age is reached. It occurs between

the different portions of bones developed in cartilage,

as in the vertebras, in the long bones of the limbs, and r'7~'::::r-::]i-cARTiL«t

in the bones of the base of the skull.

2. Suture. — In this form of articulation, which is
met with only in the skull, the bones are separated by Fig. 169.— Scheme ok a
a thin layer of fibrous tissue continuous with the peri- svnchoni^hosis. (G. d. t.)
osteum. It also exhibits a tendency to pass over

into synostosis, but in a variable degree at different places, and at a later period
than the cartilaginous union (p. 02). The suture is scrraled or dcnlated when
the contiguous margins of the bones are subdivided or broken up into pro-
jecting points and recesses by which they fit very closely to one anoi^hcr,
a« in the borders of most of the tabular bones of the cranium. The squamous
or scaly suture is that in which, as in the union of tlie tenii)oral with the parietal

148

THE ARTICULATIONS IN GENERAL.

bone, the edges are thinned and bevelled, so that one overlaps the other to
a considerable extent. Harmonic suture or harmonia is the term employed to
denote simple apposition of comparatively smooth surfaces or edges, as in the case
of the vertical j)late of the palate and the superior maxillary bones ; and the term

A.

PERICRANIUM

Fig. 170. — Various forms of suture. (Gt. D. T.)
A, dentated ; B, squamous ; C, liarmonic ; D, grooved. B, C, and D, in section.

h'^:\* ^ ^^N^.^^^'^t — BONE

Fig. 171. — Scheme of a symphysis.
(G. D. T.)

grooved suture or schindylesis is ajDplied to that kind of union in which one bone is
received into a gTOOve in another, as occurs with the rostrum of the sphenoid bone
aud the vomer.

3. Symphysis. — The bones are united by a plate or disc of fibro-carfcilage of
considerable thickness, and of a more or less complex structure, as in the articula-
tions between the bodies of the vertebrae, and
between the two pubic bones.'

4. Syndesmosis. — The bony surfaces are
united by an interosseous ligament, as in the
lower tibio-fibular articulation. Union by in-
teroEseouG membrane is also a form of syndes-
mosis, in which, the bones being more widely
separated, the intervening hgament is extended
and assumes the membranous form. In the
hand and foot the lateral connections of many
of the carpal and tarsal, as well as of the metacarpal
and metatarsal bones are partly syndesmosis, the synovial
joints extending over only a small part of the adjacent
surfaces.

Synchondroses and sutures are immoveable articula-
tions, but in symphyses and syndesmoses, which may be
classed together as partially moveable articulations, a
certain amount of play is allowed, varying in extent and
direction according to the thickness of the uniting sub-
stance and the nature of the other connections formed
by the articulating bones.
B. DiARTHROSis OR DiscoxTiNTJOUS ARTICULATION. — This division includes the
complete joints, with synovial cavities separating the articular surfaces of the bones,
and is attended with considerable yet varying degrees of mobility. In this form of
joint plates of cartilage cover the articular parts of the bones and present within the
joint free surfaces of remarkable smoothness, and these surfaces are lubricated by
the synovial fluid secreted from the delicate membrane which lines the fibrous

^ This form of articulation is sometimes regarded as a third primary division, under the name of
amxjh [arthrosis.

BSE0U3 LICAMEN

Fig. 172. — Scheme of a

SYNDESMOSIS. (G. D. T. )

VAEIODS FORMS OF JOINTS.

119

coverings and all other parts of the articular cavity except those formed by cartilage.
This membrane is continuous with the margin of the articular cartilages, and along
with them completely encloses the joint-cavity. The bones are united by fibrous
tissue in the various forms of ligaments, such as membranous capsules, flat bands,
or rounded cords. These ligaments, it is true, are not always so tight as to main-
tain the bones in close contact in all positions of the joint, but are rather tightened
in some positions and relaxed in others, so that in many cases they are to be looked

NOVIAL FOLD

Fig. 173.— Schemes of diarthrodial joints; A, simple; B, compound. (G. D. T.)

The synovial membrane is represented by a dotted line. In the natural condition the opposed
surfaces are in contact.

upon chiefly as controllers of movements. The bones are likewise held together in
diarthrodial joints by atmospheric pressure, and by the surrounding muscles. The
following forms of diarthrodial joint are distinguished :—

1. Gliding joint (Arthrodia).— The articular surfaces are nearly flat and admit
of only a limited amount of gliding movement, as in most of the articulations of
the carpus and tarsus, and in the joints between the articular processes of the
vertebra.

2. Hinge-joint (Ginglymus). — The movements are only those of flexion and
extension, the articular surfaces being either approximately cylindrical, or more
frequently the one pulley-shaped (trochlear) and the other correspondingly ridged.
To this group belong the humero-ulnar articulation, the ankle-joint, and the inter-
phalangeal articulations.

3. Condyloid joint (Condylarthrosis).— The articular surfaces are spheroiaal
and allow of all varieties of angular movement, together with circumduction, as
in the metacarpo- and metatarso-phalangeal articulations.

4. Saddle-joint.— The movements allowed are similar to those in a condyloid
joint, but the articular surfaces are reciprocally saddle-shaped, the convexity being
directed from within out on the one bone and from before back on the other, as in
the articulation of the first metacarpal bone with the trapezium.

5. Ball and socket joint (Enarthrosis).'— The articular surfaces arc approxi-
mately spherical, and movement can take place freely in any direction, as in the
shoulder and hip-joints.

6. Pivot-joint (Trochoides).— Rotation only is allowed, the articular surfaces

being cylindrical," or portions of a cone, as in the atlanto-axial and radio-ulnar

articulations.

The hinj(e and pivot-joints are uniaxial articulations, the movements taking- place around
an axi3 which in essentially transverse in the hinge-joint, althou^'h never precisely at rij^ht

' The name arthrodia is sometimes given to this form of articulation.

150 THE ARTICULATIONS IN GENERAL.

angles to tlie shafts of the two bones forming' the articulation, and longitudinal in the pivot-
joint. The condyloid and saddle-joints are biaxial, movement being permitted around two
primary horizontal axes at right angles to one another, and necessarily also around any inter-
mediate axis ; while in the ball and socket joint a third vertical axis is added, so that
movement may take place in any direction about a point in the centre of the spherical head
in which the three orthogonal axes intersect each other.

There are, moreover, certain special cases of articulations which cannot strictly be in-
cluded in any of the foregoing groups, for example, the humero-radial articulation and
the knee-joint, in both of which movements proper to a hinge- joint and a pivot-joint are
permitted.

In most diarthrodial joints the opposed articular surfaces correspond in shape
and curvature, whence they are said to be congruent; in some cases, however, the
cartilage-covered surfaces are incongruent, differing markedly in form. But even
among the articulations with so-called congruent surfaces there are frequently slight
differences of curvature, the convex surface for example being a curve of shorter
radius than the concave surface, so that the opposed surfaces are never in contact
over their whole extent. In such cases the area of contact is slightly increased
under the influence of pressure owing to the yielding of the articular cartilage, and
the small intervals left are occupied by synovial fluid and by folds of the synovial
membrane which project from the periphery of the articulation. In the more
marked degrees of incongruence larger folds containing fat fill the angular spaces
left by the separation of the articular surfaces in different positions of the joint ;
and similar adipose folds or pads are often found within the capsule, correspond-
ing to hollows formed by the bones in the neighbourhood of the articular surfaces.
Lastly, incongruence of articular surfaces is also compensated in some instances
by the interposition of an interarticidar plate or meniscus of fibro-cartilage {fibro-
plate — Cleland), which may be imperfect, having a crescentic or annular form, or
may constitute a disc entirely separating the articular surfaces, thus giving rise to
a compound joint, with two distinct synovial cavities (fig. 173, B).

Development of articulations. — Synarthrosis is the primary form of articulation, the-
adjacent skeletal elements at their first appearance being everywhere connected by indifferent
embryonic tissue, and diarthrosis arises by the formation of a cleft in this intermediate
substance. Synchondrosis results from the appearance and growth of distinct ossifications in
a continuous cartilaginous mass, and suture in a similar way from the approximation of bones-
developed in a membranous blastema. Synostosis takes place when the ossification extends
through the thin intervening layer of the original matrix. In symphysis and syndesmosis-
the connecting tissue undergoes conversion into the fibro-cartilaginous disc or interosseous-
ligament respectively. In the compound form of diarthrosis the interposed tissue becomes
converted into the meniscus, on each side of which a cleft appears. Transitional foi-ms of
articulation between synarthrosis and diarthrosis also occur, an imperfect joint-cavity being-
frequently developed by absorption of the central portion of the disc, in the symphysis pubis^
for example, and according to Luschka regularly in the intervertebral discs. (For details as
to the histological changes in the development of the joints, as well as of the microscopic
structure of their constituent parts, reference must be made to the sections on Embryology
and Histology in Vol. I.)

Morphology of ligaments. — The capsular ligaments investing diarthi-odial articulations
may be looked upon as representing a prolongation of the periosteum from one bone to
another. The articular ligaments to which special names are given are for the most part
portions of the capsule characterized by variations in thickness and the development of
definite tracts of fibres. But in addition to these there are bands of different origin occta-ring-
either in the neighbourhood of joints, or uniting more distant portions of bone. Such bands
may be derived from muscles, in the form of expansions from, or more or less separated
portions of the tendons, or as parts of the muscular sheets which have undergone fibrous
change in consequence of alteration or loss of function ; or they may represent skeletal parts
which, although indicated in the foetus, do not attain full development, as seen in the stylo-
hyoid ligament and the internal lateral ligament of the lower jaw ; or they maybe specialized
portions of fascia, as the stylo-maxillary ligament, and the supraspinous and interspinous
ligaments of the vertebrse. The annular ligaments of the wrist and ankle, as well as various-

VARIOUS KINDS OF MOVEMENT. 151

loops and retinacula binding down tendons, also belong to tlie last category.' (On this subject
see J. B. Sutton, Joum. Anat., xviii — xxii, and " Ligaments, their Nature and Morphology,"
London, 18S7.)

Various kixds of movement.— The various movements of the bones in
diarthrodial joints are distinguished by different terms, such as angular movement,
circumduction, rotation, and gliding ; but it is proper to remark that although
different kinds of movement, answering to these several terms, may readily be
recognised, yet in many cases several kinds of movement are combined in one joint,
and they also run into one another in great variety.

Angular movement is movement in such a manner as to increase or diminish
the angle between two bones, so that they shall lie more or less nearly in a straight
line. The different kinds of angular movement are designated by different terms
according to the directions in which they take place with reference to the limb or
body : thus flexion and extension indicate angular movements about a transverse
axis, which have the effect of bending or straightening parts upon one another or
upon the trunk ; adduction and ahdmtion indicate angular movement to and from
the median plane of the body, or, when fingers and toes are referred to, these
terms are generally used to denote movement to and from the middle line of the
hand or foot.

Circumduction is the movement performed when the shaft of a long bone or
a part of a limb describes a cone, the apex of which is placed in or near the joint
at one extremity of the bone, while the sides and base of the cone are described
by the rest of the moving part.

Rotation signifies movement of a bone round a longitudinal axis without any
great change of situation.

Gliding is applied to that kind of movement in which tlie surfaces of adjacent
bones are displaced without any marked angular or rotatory motion, as in the
movement of flat surfaces over each other in some of the carpal and tarsal articula-
tions, or in the movement of advance and retreat of the lower jaw.

Although the term gliding movement is used in the restricted sense indicated above, yet it
is to be observed that the movement between opposed articular surfaces is almost always
purely of a gliding nature, and that only in one or two instances, such as in the movement
of the patella on the femur, is the gliding associated with a limited degree of rolling move-
ment, by which different parts of the two surfaces are brought successively into contact in
the manner of a wheel rolling on the ground : to this form of movement the name of coaj)-
tation has been given.

I.— THE ARTICULATIONS OF THE TRUNK AND HEAD.

THE ARTICULATIONS OP THE VERTEBRAL COLUMN.

The moveable vertebrse are connected together by elastic discs interposed
between the bodies, by synovial joints between the articular processes, and by
ligaments.

The intervertebral discs are plates of composite structure placed between
the bodies of the vertcbrie i'roni the axis to the sacrum. Each is composed of a
fibro-laminar part externally, and ot a pulpy substance in the centre.

The laminar part forms more than half of the mass. The laminte are arranged
concentrically, and consist mainly of parallel bundles of fibres running obliquely
between the vertebrae and attached firmly to both, the direction of the fibres being
reversed in successive layers : some fibres also run nearly horizontally. The outer-

' The name of ligament is also given in descriptive anatomy to various structures in no way connected
with the joints or skeleton, such as folds of serous membranes and the remains of obliterated vessels.

153

THE AETICULATTOlSrS OF THE TEUNK AND HEAD.

most of these layers consist of ordinary fibrous tissue, but the deeper and more numerous
lamince consist of white fibro-cartilage. The central part of the disc is a pulpy and
elastic material which, when the pressure confining it is taken off by cutting
through the intervertebral substance, rises up so as to assume a conical form. It is

Fig. 174. A LUMBAR VERTEBRA, SEEN FROM ABOVE, WITH PART

OP THE INTERVERTEBRAL DISC ADHERING TO THE BODY.

(R. Quain.) J

1, 1, the fibrous laminae arranged concentrically ; 2, the
central soft substance.

then seen to be of a lobate structure, and, examined

under the microscope, exhibits a finely fibrous matrix,

imbedded in which are seen numerous cells which

are not of the nature of cartilage cells, but are

united together so as to form a reticular structure,

which is closer in the centre of the pulp than

towards the periphery. A thin cartilaginous layer

covers the upper and lower surfaces of each vertebra and gives attachment to the

disc, but it is incomplete towards the circumference, where the epiphyses of the body

have been developed in it.

It is generally admitted that the pulp of the intervertebral disc is in part at least a remains
of the chorda dorsalis, homologous, therefore, with those larger vestiges of the chorda
dorsalis which occupy the biconical cavities between the bodies of the vertebrse in fishes.
According to Luschka, there is present in each disc a synovial cavity, and the lobes of the
pullD are synovial villi, similar to those which are to be found in diarthrodial joints, but of
larger size, and occupying the whole cavity ; and it is worthy of notice that in like manner
secondary cavities, developed within the chorda dorsalis, are found in the intervertebral
substance in many fishes. The same author also describes in the cervical region a synovial
joint with cartilage-covered surfaces, on each side, between the prominent lip of the upper
surface of the body of one vertebra and the corresponding portion of the under surface of the
body of the vertebra above. (Luschika, " Die Halbgelenke des menschlichen Korpers," Berlin,
18.58.)

The discs are thickest, both absolutely and relatively to the depth of the vertebral
bodies, in the lumbar region, and thinnest in the intervals from the third to the

Fig. 175. — Sagittal section through two

LUMBAR VERTEBRiB SHOWING THE ARRANGE-
MENT OF THE INTERVERTEBRAL DISC.

[R. Quain.) |

1, 2, the fibrous laminee ; 3, the central soft
substance ; the capsule of the joint between the
articular j)rocesses is also shown.

seventh dorsal vertebrse. They form
together about a fourth of the length
of the moveable part of the column.
In the cervical and lumbar regions
they are thicker in front than behind,
and the curvature of these portions of the column is due principally to the form
of the discs.

The anterior common ligament (fig. 184, p. 158) is a strong band placed
on the front of the bodies of the vertebrae, and reaches from the axis to the first
piece of the sacrum, becoming broader as it descends. It consists of longitudinal
fibres which are dense, firm, and well-marked. The superficial fibres extend from
a given vertebra to the fourth or fifth below it ; the fibres beneath these pass over

THE ARTICULATIONS OF THE VERTEBRAL COLUMN.

153

the bodies of one or two vertebrae ; while the deepest pass only between adjacent
vertebrEe. The fibres adhere more closely to the intervertebral discs than to the
bones, and none are attached over the middle of the bodies, where the ligament is
stretched across the transverse depression existing at this part ; and by this means
the anterior surface of the column, especially in the thoracic region, is rendered
more even. Upon the sides of the bodies there are some fibres which are thin and
scattered, and reach from one bone to another.

The posterior common ligament is situated within the spinal canal, lying
on the posterior surface of the bodies of the vertebrae ; it extends from the axis to

176.-

-ThE bodies of three lumbar VERTEBR.E, SEEN FROM BEHIND,
WITH THE POSTERIOR COMMON LIGAMENT. i

The arches have been removed by cutting through the pedicles. The narrow-
ing of the posterior common ligament opposite the middle of each body, ;ind its
greater width and attachments opposite the intervertebral discs, are represented.

the sacrum. At its upper extremity it is continuous with the

posterior occipito-axial ligament. It is smooth and shining, and is

broader at the upper than at the lower part of the spine. In

the neck it extends aci-oss nearly the whole breadth of the bodies

of the vertebraB, but in the back and loins it is broader opposite

the intervertebral discs than at the middle of the bodies, so that its margins present

a series of points or dentations with intervening concave spaces. It adheres firmly

to the discs and to the contiguous margins of the bodies of the vertebras, but it is

separated from the middle of the bodies by the transverse parts of the large venous

plexus. Between the ligament and the dura mater which lines the canal some loose

connective tissue is interposed.

The joints of the articular processes have each a synovial cavity sur-
rounded by a fibrous capsule. These capsules are shortest in the dorsal region,

Fig. 177. — The arches uf three dorsal vertebr.e, seen from

BEFORE. 3

The bodies of the vertebrse have been removed by sawing tliough
the pedicles, to show the articular capsules and the ligamenta subflava

strongest in the loins, and longest and loosest in the
neck.

The ligamenta subflava are ligaments consisting of
yellow elastic tissue, which connect the laminae of the
vertebrse from the axis downwards. Their fibres are
nearly vertical, and are attached above to the antericn-

surface of the laminas of one vertebra some distance from its inferior margin, and
below to the upper margin and part of the posterior surface of the laminae of the
succeeding vertebra. They are best seen when the arches are detached from the
lx)dies of the vertebrae, and viewed from the front. Posteriorly they appear short,
and in the dorsal region are concealed by the prominent inferior margins of the
laminae and the roots of the spines. Their outer margins are close to the articular
processes ; their inner margins are thickened and in contact with each other beneath
the root of the spinous process.

The interspinous ligaments are membranous bands in the intervals between
the spinous processes, each Ijeiug attached to the lower border of one process and the
upper border of that next below it. Jn front they meet the ligamenta subflava, and
behind they join the supraspinous ligament. They are small and thin in the mid-

154

THE ARTICULATIONS OF THE TRUNK AND HEAD,

dorsal region, largest and strongest in the loins, where a band of nearly horizontal
fibres extends on each side from the fore part of the upper border of one spine to
the hindmost part of the lower border of the spine above.

The supraspinous ligament consists of bundles of longitudinal fibres, which
connect the summits of the spinous processes, and form a continuous cord from the
seventh cervical vertebra to the sacrum. The superficial fibres pass down from a
given vertebra to the third or fourth below it ; those more deeply seated reach only
from one to the next, or the second below it.

The ligamentum nuchse replaces the supraspinous and interspinous ligaments
in the neck. Its superficial part, which forms a continuation of the supraspinous

«^,>?>"\ 2' , V -^'S" ■'''^* — Sagittal section of the upper part of the

VERTEBRAL COLUMN, AND PART OF THE OCCIPITAL BONE,

SHOWING THE ARTICULATIONS. (Allen Thomson, after
Arnold.)

1, 1, anterior common ligament ; 1', anterior occipito-
atlantal ligament ; 2, from this figure upwards the posterior
common ligament ; 2', the continuation of the preceding or
posterior occipito-axial ligament lying on the basilar pirocess of
the occipital bone ; 3, 3, 3, these figures are placed on the
■inside of the arches of the 2nd cervical and 1st and 6th dorsal
vertebrte ; the ligamenta subflava are seen stretching between
the laminse ; 4, 4, placed upon two of the interspinous liga-
ments ; 4', divided edge of the occipital bone behind the
foramen magnum, and below it, the posterior occipito-atlantal
ligament ; 5, 5, supraspinous ligament ; 6, ligamentum nuchse ;

X , its upper extremity at the external occijjital protuberance ;

XX, its lower extremity terminating in the suxDraspinous
ligament.

ligament, is thick and extends from the spine of
ths seventh cervical vertebra to the external occi-
pital protuberance. From this a thin median
septum is continued forwards to the external occi-
pital crest and the spines of the upper vertebra?, as
well as into the intervals between the latter. The
ligament consists in man mainly of white fibrous
tissue ; but in the lower animals it is a strong
elastic structure which supports the head.

The supra- and interspirLous ligaments, together
with the ligamentum nuchte, are derived from the
median dorsal intermuscular septum. In the lumbar region the spinous processes of adjacent
vertebrse sometimes become united by synovial articulations near their free extremities.

The intertransverse ligaments are unimportant bands extending between the
transverse processes. In the lumbar region they are membranous and correspond to
the anterior superior costo-transverse ligaments of the ribs ; in the mid-dorsal
region there are small rounded bundles taking the place of the intertransverse
muscles of the lower spaces ; and in the upper dorsal and cervical regions they are
generally wanting.

Movements, — The movements of flexion and extension of the vertebral column are freely
allovred in the cervical and lumbar regions, but in the dorsal are limited by the small amount
of intervertebral substance and the imbrication of the lamina. The greatest bending back-
wards is permitted in the cervical, the greatest bending forwards in the lumbar region,
especially between the last three vertebrEe. Movements in other directions are determined
chiefly by the articular processes. In the dorsal region the articular surfaces of each vertebra
lie in the arc of a circle the centre of which is in front, between the bodies of the vertebra.

ARTICULATIONS OF THE ATLAS, AXIS, AND OCCIPITAL BONE. 155

und roxrnd this centre a certain degree of rotation is permitted. In the lumbar region, the
■centre of the circle in which the articiilar surfaces lie is placed behind, so that rotation is
prevented : the articular processes, however, permit of lateral flexion, and by combination of
this with antero-posterior flexion, some de^-ree of circumduction is produced. The articular
surfaces of the cervical vertebra;, being oblique and placed in nearly the same transverse plane,
allow neither pure rotation nor pure lateral flexion. They permit, besides forward and
backward motion, only one other, which is rotatory round a median axis, directed obliquely
from above and behind downwards and forwards — the inferior articular process of one side
gliding upwards and forwards on tlie ojjposing surface, and that of the other side gliding
downwards and backwards, by which a combination of lateral flexion and rotation is
obtained.

THE ARTICULATIONS OF THE ATLAS, AXIS, AND OCCIPITAL BONE.

The atlas, axis, and occipital bone are connected by synovial articulations and
ligaments, without the presence of intervertebral discs.

Two pairs of synovial articulations, surrounded by capsular ligaments,

connect the lateral masses of the atlas with the superior articular surfaces of the

Fig. 179 — Coronal section of the lower

P.\RT OF THE OCCIPITAL BONE, AND THE

FIRST TWO vertebra:, behind the
ARTICULATIONS. (Allen Thomson, after
Arnold, ) i

1, 1, posterior occipito-axial ligament
turned up in two layers ; 2, 2', vertical part,
and 3, 3, transverse or principal part of the
cruciform ligament ; x , over the neck of
the odontoid process ; 4, 4, lateral odontoid
•or check ligaments ; 5, 5, accessory ligaments
of the athinto-axial capsules ; 6, 6, capsular
ligaments of the condylar articulations ;
7, 7, capsular ligaments of the atlanto-axial
articulations,

axis and with the condyles of the occipital bone. The atlanto-axial capsule is
strengthened at the inner and posterior part by an accessory ligament, directed
downwards and inwards to the body of the axis near the base of the odontoid
process.

The transverse ligament of the atlas is a strong and thick band, which
extends across the ring of the atlas, and retains the odontoid process in its place.

Fig. 180. — Horizontal section through the odonto-
ATLANTAL ARTICULATION, (Allen Thomson.) ^

1, cut surface of the odontoid process ; 2, cut surface of the
anterior arch of the atlas ; 3, transverse ligament ; between 1
and 2, the anterior synovial cavity, and between 1 and 3, the
posterior synovial cavity of the ai-ticuhition ; 4, is placed on the
back part of the left superior articular jji-oce-ss of the atlas ;
the anterior part, has been partly removed by the section. For
the sake of distinctness, the .synovial spaces are represented
wider than natural.

It is attached on each side to the tuljercle below the inner border of the supei'ior
articular process. It is arched backwards behind the neck of the odontoid process,
and is broadened out in its central part. From the middle of its posterior surface
a short thin Imndle of fibres passes down to be attached to the body of the axis,
while another passes up to the basilar process. These form, with the transverse
portion, the figure of a cross, and from this arrangement is derived the term
cruciform, wliich is sometimes applied to the transverse ligament and its appendages
together.

156

THE ARTICULATIONS OF THE TRUNK AND HEAD.

Two synovial cavities are placed one in front of and the other behind the
odontoid process ; the first of these is situated between the process and the anterior
arch of the atlas ; the other, which is the more extensive of the two, is between the
process and the transverse ligament.

The lateral or alar odontoid or check ligaments are two short but very

1%;, ;'|4iv

Fig. 181. — Transverse section similar to that shown in

FIG. 179, THE CRUCIFORM LIGAMENT HAVING BEEN RE-
MOVED. (Allen Thomson.) ^

4, alar odontoitl ligament ; 5, accessory atlanto-axial liga-
ment ; 6, 7, caiDsular ligaments of the occipito-atlantal and
the atlanto-axial articulations : 9, odontoid process ; 9, 9',
middle odontoid ligament.

strong bundles of fibres, which extend from the
sides of the summit of the odontoid process out-
wards and a little upwards to be implanted into
the rough impression on the inner side of each

VCHT ART

ENT. ODONTOID LIGT..

SPHENOIDAL
SINUS

POST. COMMON
LIG. DENTICULATUM

Fig. 182. — Median section op the first three cervical vertebra and part of the occipital.
BONE, WITH THEIR LIGAMENTS, &c. (Drawn by T. W. p. Lawrence.)

V to XII, fifth to twelfth cranial nerves ; C I to C IV, first to fourth cervical nerves.

condyle of the occipital bone. Some of the upper fibres of the two ligaments are-
usually continuous across the middle line.

The middle odontoid or suspensory ligament is a small cord which passes

ARTICULATIONS OF THE ATLAS, AXIS, AND OCCIPITAL BONE. 157

directly upwards from the summit of the odontoid process to the centre of the
anterior margin of the foramen magnum.

The central odontoid lirrament is developed around the notochord in the interval between
the basioccipital and first vertebral centrum, and may therefore be said to represent an inter-
vertebral disc. The transverse ligament of the atlas and the lateral odontoid ligaments are
derived from ligamenta conju<ralia costarum (p. 1.59).

The posterior occipito-azial ligament is a strong wide band, covering the
cruciform and odontoid hgaments. It is attached above in the basilar groove of the
occipital bone, and below to the body of the axis : many of the superficial fibres are
prolonged into the posterior common ligament, of v/hich it forms the continuation
upwards.

The anterior occipito-atlantal ligament extends from the anterior border
of the occipital foramen, between the condyles, to the anterior arch of the atlas.

Fig. 183. — The ligamextois structures which surround the articulatioxs oe the occiput

AND TWO UPPER VERTEBR.E. }^

A, the lower part of the skull sawn transversely through the basilar process, with the atlas and axis,
viewed from before. 1, anterior occipito-atlantal ligament ; 2, accessory occipito-atlantal ligament ; 3,
anterior atlanto-axial ligament.

B, the lower jtart of the skull, with three adjacent vertebrie, viewed from behind. 1, posterior
occipito-atlantal ligament ; 2, posterior atlanto-axial ligament.

C, the occipital bone sawn transversely through the foramen magnum, and a part of the arches of
the atlas and axis removed, so as to show the posterior occipito-axial ligament.

It is thill and membranous ; but in the median line it is strengthened by an acces-
sory ligament, thick and round, placed in front of it, whicli is sometimes described
as the commencement of the anterior common ligament.

The anterior atlanto-axial ligament, likewise thin and membranous, except
in the middle, where it is similarly thickened by a prolongation of the anterior
common ligament, extends from the anterior arch of the atlas to the body of the
axis.

The posterior occipito-atlantal ligament, thin and membranous, is attaclicd
superiorly to tiie margin of the occipital foramen behind the condyles, and inferiorly

158

THE ARTICULATIONS OF THE TRUNK AND HEAD.

to the adjacent border of the arch of the atlas : it is closely united to the dura
mater. A small band on each side forms an arch between the back of the vertebral
groove and the posterior end of the superior articular process of the atlas, thus
completing a foramen through which pass the vertebral artery and the suboccipital
nerve. This arch is not unfrequently ossified (p. 8).

The posterior atlanto-axial ligament, similar to the preceding, connects the
neural arch of the atlas with that of the axis, in the place of ligamenta subflava.
It is perforated on each side by the second cervical nerve.

Movements. — The atlanto-axial articulation is so constructed tliat the head, together
with the atlas, is rotated on the axis, the odontoid process serving as a pivot. The rotation
is limited by the check ligaments : its extent is about 80° to either side. The occipito-
atlantal articulation takes no part in rotation, but allows the head to be freely raised or
depressed upon the vertebral column. When the atlas is placed symmetrically over the axis,
it is seen that the opposing articular surfaces, instead of fitting one to the other, come very
slightly into contact, the surface of the axis presenting an antero-posterior convexity, to
which there is no corresponding concavity presented by the atlas ; but a slight rotation
brings the bones into a stable position, in which the anterior half of one articular surface of
the axis and the posterior half of the other are laid closely against the atlas. It will also be
found that a small amount of oblique motion between the atlas and occipital bone is per-
mitted, by which the anterior half of one condyle and the posterior part of the other may be
rested together on the atlas, and that that is the position of greatest stability. This oblique
position is that into which the bones are brought when there is any lateral flexion of the
column, as is the case in the most natural and easy attitudes.

THE ABTICULATIONS OF THE THORAX.

The articulations of the ribs with the vertebra are divided into costo-central and
costo-transverse. Anteriorly the costal cartilages are connected to the sternum by

Fig. 184. — The 5th, 6th, 7th, 8th, and 9th dorsal

VERTEBRA, WITH PARTS OF THE 6tH, 7tH, AND
8th ribs, from the RIGHT SIDE AND FRONT.

(Allen Thomson.) -g

The 9tli rib has been removed to show the articular
surfaces of the vertebrse corresponding to it ; 3 and 4,
tlie heads of the 6th and 7th ribs, from which the
stellate ligaments are seen sjireading over the two adja-
cent vertebral bodies and intervertebral substance ; .5,
the head of the 8th rib, from which the stellate liga-
ment has been removed, so as to expose the upper
and lower synovial cavities, and between them the
interarticular ligament ; 6, lower, and 6', upper facet
of the costo-central articulation ; 7, posterior costo-
transverse ligament ; 7', the costo-transverse synovial
cavity ; 7", the costo-transverse articular facet ; 8,
anterior superior costo-transverse ligament ; 9, superior
articular process of the 5th vertebra; 9', inferior of the 9th.

the cliondro-sternal articulations, and with
one another by the interchondral articulations.
The three portions of the breast-bone are
united by the sternal articulations.

The COSTO-CENTEAL ARTICULATION Uuites

the head of the rib, in most instances, with
the bodies of two vertebr£e by two distinct

synovial joints, supported by hgaments as follows.

The anterior costo-central or stellate ligament consists of fibres which

radiate from the head of the rib to the body of its proper vertebra, to the intervertebral

•disc, and to the body of the vertebra above Short fibres surround the remaining

portion of the articulation and complete a capsule to the joint.

THE ARTICULATIONS OF THE BIBS.

159

The interarticular ligament is a thiu and short band of fibres, which passes
transversely li-om the ridge separating the two articular surfaces on the head of the rib
to the intervertebral disc, and divides the articulation into two parts, each lined
bj a separate synovial membrane. The ligament does not exist in the articulations
of the first, eleventh, or twelfth ribs, as these ribs are each attached to only one
vertebral body by a single synovial joint.

Conjug-al ligament. — In many mammals there is a band known as the lif/amcnfum conju-
galc costavHut nnitinu' the heads of opposite ribs aci'oss the back of the intervertebral disc. This
ligament is represented in man by fibres passing from the hinder part of the neck of the rib
through the intervertebral foramen to the back of the intervertebral disc and the correspond-
ing process of the posterior common ligament of the vertebrse (Jit/, conjiigale colli codee —
Luschka). According to Sutton the conjugal ligament is distinct in the human foetus from
the seventh month, and the interarticular ligament is derived from its outer end.

The cosTO-TRAXSVERSE ARTICULATION unites the tuberosity of the rib to the
corresponding transverse process by a simple synovial joint, and ligaments pass
from the tuberosity and neck of the rib to the transverse processes of its proper
vertebra and of the vertebra above.

The posterior costo-transverse ligament is a distinct band extending out-
wards from the posterior part of the summit of the transverse process to the rough

Fig. 185. — HORIZO.NTAL SECTION OF A DORSAL
VERTEBRA, WITH THE ADJACENT PORTIONS

OF TWO KiBs. (R. Quain.) §

1. rib ; 2, transverse process; 3, anterior costo-
central ligament ; 5. posterior costo-transverse
ligament ; 6, midJle costo-transverse ligament.

external part of the tuberosity of the
rib.

The middle or interosseous
costo-transverse ligament consists
of a series of short parallel fibres, which

unite the neck of the rib to the anterior surface of the contiguous transverse process.
These fibres are seen on removing by horizontal section a portion of the rib and
transverse process, and forcibly drawing the one from the other.

The superior costo-transverse ligaments are two in number, anterior and
posterior. The anterior is a flattened band composed of fibres which pass from a
ridge on the upper border of the neck of the rib upwards and outwards to the lower
margin of the transverse process next above it. Its internal margin is thickened
and free ; externally it is continued into the posterior intercostal aponeurosis, which
occupies the hinder portion of the intercostal space. The posterior is a smaller and
less regular fasciculus extending from the neck of the rib upwards and inwards to the
base of the transverse process and the outer side of the lower articular process of the
vertebra above. These ligaments are wantine; to the first rib.

A third ascending band, external to the last, is sometimes present, running
part of the tuberosity of the rib to the tip of the transverse process above.

from the outer

There are no synovial joints between the lowest two ribs and the transA'crse
proces.se8, and the posterior and middle costo-transverse ligaments are represented
Ly a single band.

The riiONDUO-STERXAL ARTICULATIONS, situated between the inner extremities
of the cartilages of the sternal ribs and the corresponding fossa} in the niai'gins of
the sternum, are, with the exception of the first, small synovial joints, surrounded

160

THE AETICULATIONS OF THE TRUXK AND HEAD.

by short capsules, which are most developed in front and behind, and thus form
anterior and posterior ligaments. The fibres of the anterior ligament radiate from
the extremity of the cartilage to the anterior surface of the sternum, where they
interlace with those of the opposite side, and are blended with the tendinous fibres
of orio^in of the pectoralis major muscle ; the fibres of the posterior ligament are
similarly disposed, but are not so thick or numerous. In the second articulation
the synovial cavity is divided into two by a short interarticular ligament, passing
horizontally between the end of the costal cartilage and the fibro-cartilaginous layer
uniting the manubrium to the body of the sternum ; and similar divisions some-
times exist in the succeeding joints. The synovial cavity is frequently wanting

Fig. 186. — Articulations of the sternum, cla-
vicle, AND RIBS, SEEN FROM BEFORE. (Alien

Thomson, after Arnold.) 5

On the right side the anterior ligaments are
shown ; on the left side, the front parts of the cla-
vicle, sternum and costal cartilages have been re-
moved so as to display the articular cavities. 1
to 10, the anterior extremities of the ribs from the
first to the tenth inclusive, on the right side ; 1' to
10', the costal cartilages of the left side from the
first to the tenth ; at 1', the direct union of the
first costal cartilage with the sternum is shown ; at
the sternal ends of the cartilages marked 2' to 7',
the small synovial cavities are opened ; between the
costal cartilages on the right side the anterior
intercostal aponeuroses are shown stretching over
the intercostal sj)aces ; and on the left side, by a
section, small synovial cavities are shown between
the adjacent edges of the costal cartilages from the
5th to the 9th ; on the front of the right half of the
sternum the radiating anterior chondro-sternal liga-
ments are shown ; 11, ensiform process ; 12, 12',
interclavicular ligament ; and below 12, the anterior
sterno-clavicular ligament ; below 12', the sterno-
clavicular articulation is opened, showing the inter-
articular fibro-cartilage and double synovial cavity ;
13, the costo-clavicular or rhomboid ligament.

in the articulations of the sixth and seventh
cartilages. The cartilage of the first rib
is almost always directly united to the
sternum.

A variable fasciculus of fibres connect-
ing the cartilage of the seventh rib and
■sometimes likewise that of the sixth, with the xiphoid cartilage, is cahed the costo-
xiphoid. ligament.

The iNTEECHONDRAL ARTICULATIONS are Synovial joints formed by the processes
on the adjacent margins of some of the costal cartilages, viz., from the fifth (sometimes
the sixth) to the eighth or ninth, surrounded by short capsules. The joints are
strengthened anteriorly by oblique ligamentous fibres, derived fi'om the anterior
intercostal aponeuroses which occupy the fore parts of the intercostal spaces.

Connection of the ribs with the cartilages. — The external extremities
of the cartilages are fixed into the oval depressions on the ends of the ribs, and the
union receives support from the periosteum.

A synovial joint is occasionally formed between the first rib and its cartilage, or in the
outer part of the cartilage when ossification around the latter is far advanced. (Luschka,
" Die anomalen Articulation en des ersten Eippenpaares," Wiener Sitzungsber., 1860 ; W. A. Lane,
Guy's Hosp. Eeports, xliii.)

MOVEMENTS OF THE RIBS.

161

Sternal articulations. — The manubrium and Ijody of the sternum are united
by a symphysis, the disc being composed of a layer of cartilage above and below,
with a central fibro-carfcilagiuous stratum, in which a cavity is frequently formed.
The articulation is farther supported by anterior and posterior ligamentous fibres,
which have chiefly a longitudinal direction, and are most developed on the back of
the sternum. The whole sternum is much strengthened by thick periosteum and
the radiating fibres of the chondro-sternal ligaments already mentioned. A layer

Fig. 187. — Diagram of first and seventh ribs, in con-
nection WITH THE SPINE AND THE STERNUM, SHOWING
HOW THE LATTER IS CARRIED UPWARDS AND EORWAItDS
IN INSPIRATION. (G. D. T. )

The expiratory position is indicated by continuous lines,
the inspiratory by broken lines.

of cartilage intervenes between the body and
ensiform process so long as they are not united
by bone.

Movements of the ribs. — The chief movement
of the ribs •generally is one of rotation, upwards and
downwards, about an axis which is directed obliquely
outwards and backwards, as well as mostly somewhat
downwards, i a^sing throug-h the costo-central articu-
lation and the neck of the rib. and a little in front of
the costo-transverse joint. Owing- to the downward
inclination of the ribs as they extend forwards, their
anterior ends when elevated also advance, so that
the front wall of the chest is carried upwards and
forwards in inspiration, thus increasing the sagittal

Fig. 188. — Diagram of THr. fifth thoracic ver-
tebra AND COSTAL ARCH, PROJECTED ONTO A
HORIZONTAL PLANE, TO SHOW THE AXIS OP MOVE-
MENT OF THE KIB, AND THE MANNER IN WHICH
THE SAGITTAL AND CORONAL DIAMETERS OP THE
THORAX ARE INCREASED. (G. D. T.)

The continuous lines indicate the position in
expiration, the broken lines in inspiration.

'diameter of the thorax. At the same time, by

reason of the obliquity of the axis, the anterior

and lateral parts of the ribs move outwards,

giving rise to the so-called eversion of the ribs,

and the transverse diameter of the cavity is

increased. This lateral movement of the fore

part of the rib is accompanied by an opening

out of the angle between the rib and its costal

•cartilage. The degree of lateral expansion

is necessarily proportionate to the obliquity

of the axis of movement. In the first rib the

axis is nearly transverse, and thus, while a

considerable degree of elevation is permitted,

the eversion is but slight. In proceeding

downwards the transverse processes of the vertebraj and the necks of the ribs become

more inclined backwards, so that the oblicjuity of the axis increases, and the outward

movement becomes more extensive. In the upper si.x ribs, the convex tuberosities of

which are received into small hollows on the corresponding transverse processes, this rotation

is the only movement allowed ; but from the seventh to the tenth the costo-transverso joints

have nearly plane articular surfaces, the vertebral facets lieing placed at the upi)cr and fore

part of the extremity of the transverse process, and these ribs move backwards as well as

162

THE AKTICULATIONS OF THE THUNK AND HEAD.

upwards in inspiration, forwards and downwards in expiration. The last two ribs, forming-
no costo-transverse articulations, move freely backwards and forwards, while the up and
down movement is more limited : the twelfth rib in inspiration is drawn backwards and
rather downwards. When the vertebral column is extended, the ribs are raised and separated ;
and when the column is bent forwards, the ribs are depressed and brought together. The
combined movements of the chest-walls in respiration will be considered with the actions of
the thoracic muscles.

TEMPORO-MAXILLARY ARTICULATION.

The articular surfaces of this joint are the condyle of the lower jaw, which is
approximately a portion of a cylindrical body, with its axis directed from without

Fig. 189. A PORTION OP THE SKULL WITH THE

LOWER JAW AND HYOID BONE, SEEN FROM

THE OUTER SIDE. (Allen Thomson, after
Arnold. ) J

1, external lateral ligament of the tempore-
maxillary articulation ; 2, a part of the capsule
of the joint ; 3, styloid process ; 4, stylo- maxil-
lary ligament ; 5, stylo-hyoid ligament ; 6, lesser
cornu of the hyoid bone with some short liga-
mentous fibres attaching it to, 7, the body, and
8, the great cornu.

inwards and slightly backwards, and
the surface of the squamous portion
of the temporal bone extending over
the part of the glenoid fossa in front
of the Glaserian fissure and the articular-
eminence formed by the anterior root
of the zygoma. The two are' markedly
in congruent, and the temporal surface is much larger than that of the inferior
maxilla. The incongruence is compensated by the interposition of a meniscus

Fig. 190. — A PORTION OF THE SKULL AND LOWER JAW
WITH HALF THE HYOID BONE, SEEN FROM THE INSIDE.

(Allen Thomson.) g

The numbers are the same as in fig. 189; 3, styloid
process, detached from the skull ; 7, posterior surface of the
right half of the body of tbe hyoid bone ; 9, internal
lateral ligament of the temporo-maxillary joint ; 10, infe-
rior dental foramen.

which divides the joint into an upper and a
lower synovial cavity. The layer clothing the
articular surfaces of the bones is composed of
fibro-cartilage.

The external lateral ligament is a short
fasciculus of fibres, attached above to the lower
border and the tubercle of the zygoma ; and
below to the external surface and posterior
border of the neck of the lower jaw, its fibres

being directed downwards and backwards. Scattered ligamentous fibres cover the

synovial membrane in front, on the inside, and behind, forming a thin and loose

capsule round the joint.

The internal lateral ligament is a flat, thin band, placed at some distance

from the joint It extends from the spinous process of the sphenoid bone down-

THE TEMPORO-M AXILLARY ARTICULATION.

163

wards and a little forwards, to be attached to the liugula and the lower border of
the inferior dental foramen. Between it and the lower jaw are placed the external
pterygoid muscle, the internal maxillary vessels, the auriculo-temporal nerve, and
the inferior dental vessels and nerve.

The internal lateral ligament is formed in the tissue surrounding a part of Meckel's
cartilage (p. 7S).

The interarticular disc (ir meniscus is a thin plate of fibro-cartilage
placed between the articular surfaces of tlie bones. It is of an oval form, broadest
transversely, thickest posteriorly, and thinnest at its centre, where it is sometimes
perforated. The inferior surface, which is in contact with the condyle, is concave ;
the superior is concavo-convex from before backwards, conforming with the articular
surface of the temporal bone. Its circumference is attached closely to the capsule,
and anteriorly a part of the external pterygoid muscle is inserted into it.

Synovial sacs. — The synovial sac between the interarticular disc and the
glenoid cavity is larger and looser than that which is interposed between the disc

Fig. 191. — Sagittal section of the temporo-

MAXILLARY ARTICULATION OP THE lUGHT

SIDE. (Allen Thomson.) 3

1, is placed close to the articular eminence,
and points to the superior synovial cavity of the
joint ; 2, is placed close to the articular surface
of the condyle of the lower jaw, and poinhs to
the inferior synovial cavity of the joint ; x , is
placed on the thicker posterior portion of the
interarticular disc.

and the condyle of the jaw. When
the fibro-cartilage is perforated, the
upper and lower synovial cavities neces-
sarily communicate with each other.

The stylo-maxillary ligament is
the name given to a sti-ong band of
the cervical fascia extending from the styloid process to the angle and posterior
border of the ramus of the jaw, where it is inserted between the masseter
and internal pterygoid muscles. It S3parates the ]mrotid from the submaxillary
gland.

It may be proper also to mention here the stylo-hyoid ligament, a thin
fibrous cord, which passes from the point of the styloid ])rocess to the lesser cornu
of the hyoid bone, and susj)ends that bone from the styloid pi'ocoss. A consider-
able portion of the stylo-hyoid ligament is sometimes converted into bone in the
human subject, and in many animals it is naturally osseous, constituting the ppihyal
hone.

Movements. — The jaw is capable of movements of e.evation and depression, and of
protrusion and retraction ; but it is to be observed that when the jaw is depressed, as in
0[)ening the mouth, the condyle advances from the glenoid cavity so as to be placed on the
articular eminence in front of it. The movements which take place in the superior and
inferior compartments of the joint are of different kinds. In the upper the fibro-cartilage
glides forwards and backwards on the temporal bone ; in the lower compartment the
condyle rotates on a transverse axis against tlie fibro-cartilage. In opening the mouth the
two movements are combined ; tlu; jaw and fibro-cartilage together move forwards and rest
on the convex root of the zygoma, while at the same time the condyle rc^volvcs on the fibro-
cartilage. The point of hiast movement corresponds approximately to the position of the
inferior dental foramen, so that streteliing of the inferior di^ntal nerv«! is avoidcid. Whtm the
lower incisors are protruded beyond those of the upper jaw, tlic movement is confined chiefly

164 THE ARTICULATIONS OF THE UPPER LIMB.

to the upper articulation ; and when the same movement is alternately performed in the
joints of opposite sides a horizontal oblique or grinding motion is produced. The fibres of the
external lateral ligament remain tight in opening the mouth, owing to the descent of the
condyle when it passes forwards on to the articular eminence.

II.— THE ARTICULATIONS OF THE UPPER LIMB.

THE SCAPUIiO-CLAVICULAR AECH.

The supporbing arch of the upper limb has only one point of attachment to the
skeleton of the trunk, namely, at the sterno-clavicular articulation, the scapula being
connected with the trunk only by muscles.

The clavicle articulates at its inner end with the first piece of the sternum, and
is connected by hgaments also to its fellow of the opposite side and to the first rib.
At its outer end it is united to the scapula.

Steeno-clavicular articulation. — The articular surface of the inner end of
the clavicle is considerably larger than the opposing surface of the sternum, and the
investing layer of both surfaces is composed mainly of fibro-cartilage. The joint is
surrounded by a fibrous capsule, which is of considerable thickness in front and
behind, forming anterior and posterior ligaments, but very thin at the lower and
outer part, between the inner end of the clavicle and the first rib-cartilage. Between
the two bones an interarticular fibro-cartilage is interposed.

The anterior sterno-clavicular ligament, broad and consisting of parallel
fibres, passes from the front of the inner extremity of the clavicle, downwards and
inwards, to the anterior surface of the manubrium.

The posterior sterno-clavicular ligament, on the posterior aspect of the
joint, is of similar conformation to the anterior ligament, but is not so strongly
marked.

The interclavicular ligament is a dense fasciculus of fibres passing between
the sternal ends of the clavicles. It dips downwards in the middle, where it is
attached to the interclavicular notch of the sternum.

The interarticular fibro-cartilage, nearly circular in form, and thicker
above and at its margins than at the centre, is interposed between the articular
surfaces of the tv/o bones. Superiorly it is attached to the upper part of the inner
extremity of the clavicle, and inferiorly to the cartilage of the first rib. In the
latter situation it is thin and prolonged outwards, beneath the lower border of the
clavicle.

Synovial cavities. — There are two synovial cavities in this articulation, one
on each side of the interarticular fibro-cartilage. The outer one is the more exten-
sive, and is continued a short distance below, between the clavicle and first costal
cartilage.

The interarticular fibro-cartilage is occasionally defective or wanting, in which case there
is only one synovial cavity. The interclavicular ligament and interarticular fibro-cartilages
together represent the epistemal bone of monotremes and lizards.

The CO sto- clavicular or rhomboid ligament may be regarded as an accessory
ligament of the sterno-clavicular articulation. It is attached inferiorly to the
cartilage of the first rib near its sternal end, and passes obliquely upwards,
backwards and outwards, to be fixed to a rough impression on the under surface of
the clavicle near the sternal end. The ligament is sometimes hollow, containing a
bursa.

ScAPULO-CLAVicuLAR ARTICULATION. — At its outer end the clavicle is connected
to the acromion and coracoid processes of the scapula.

THE SCAPULO-CLAVICULAR ARCH.

165

The acromio-clavicular articulation is a synovial joint unitini^ the outer
extremity of the clavicle with the inner edge of the acromion. Both articular sur-
faces are covered with fibro-cartilage. The articulation is supported above by a
thick and broad superior lujament, and below by an inferior ligament which is very
thin. A small inierarticular fibro-rariiUuje is sometimes present. It is wedge-shaped,
attached by its base to the superior ligament, and projects only a short distance
between the articular surfaces. In rare cases it effects a complete division of the
joint.

The coraco-clavicular ligament, which connects the clavicle with the coracoid
process of the scapula, is divisible iuto two parts. The conoid ligament, which is the
posterior and internal fasciculus, broad above, narrow below, is attached inferiorly to
the inner part of the root of the coracoid process, and superiorly to the conoid

Fig. 192. — View frosi ekfdre op the artichlations op the shoulder-boxes. (Alleu Thomson.) \

1, acromio-clavicular aiticulation ; 2, conoid, and 3, trapezoid part of the coraco-clavicular liga-
ment : 4, near the suprascapular ligament ; 5, on tiie coracoid process, points to the coraco.acromial
ligament ; 6, capsular ligament of the shoulder-joint ; 7, coraco-humeral ligament ; above 6, an
aperture in the capsular ligament through which the synovial membrane is prolonged under the tendon
of the subscapularis muscle ; 8, tendon of the long head of the biceps muscle ; 9, right half of the
interclavicular ligament; 10, interarticular tibro-cartilage of the sterno-clavicular articulation; 11,
costo-clavicular ligament ; 12 and 13, cartilage and small part of the second and third ribs attached by
tbeir anterior chondro-sternal ligaments.

tubercle of the clavicle: its fibres are directed backwards and upwards. The trapezoid
tigametit, the anterior or external fasciculus, slopes upwards, backwards and outwards
from the posterior half of the upper surface of the coracoid process to the trapezoid
line, on which it is inserted into the clavicle. In the angle between t.^e conoid and
trapezoid ligaments there is frequently a synovial bursa.

A complete Hynovial joint is occasionally formed between the clavicle autl the first rib-
cartilat'ft internally, or between the clavicle and the coracoid process externally.

Movements, &c. — 'J'he clavicle is finnly bound <lo\vn at its inner end in the sterno-
clavicular articulation, and upon this as a centre it can be moved upwards and downwards,
forwards and backwards, or in any intermediate direction, necessarily carrying with it the
scapula, which glides in a corresponding direction over the thoracic wall. The scapula farther
ondergoee a movement of rotation, by which the acromion is raised and the glenoid cavity

M 2

166 THE ARTICULATIONS OF THE UPPER LIMB.

directed upwards when the arm is elevated, and the reverse when the arm is depressed. A
limited degree of rotation of the clavicle upon its long axis is also permitted, the anterior
surface turning upwards as the arm is raised.^ The movements of the bones are limited, not
so much by the forms of the articular surfaces, as by the costo-clavicular and coraco-
clavicular ligaments, and the position of the thoracic wall. When the clavicle is forcibly
depressed, as in lifting a heavy weight, it presses upon the first rib, its sternal end rises, and
the interarticular fibro-cartilage and interclaviciilar ligament, as well as the anterior and
posterior ligaments, are put upon the stretch. The interarticular fibro-cartilage also resists
pressure from the shoulder conveyed through the clavicle, and prevents that bone from being
displaced inwards. The rhomboid ligament limits upward and backward movements of the
clavicle. The acromio-clavicular joint is loose and allows of considerable play, by which the
angle between the spine of the scapula and the clavicle is altered as the shoulder is moved ;
and the scapula is supported on the clavicle principally by the strong' coraco-clavicular
ligament, the conoid division of which suspends the scapula from the clavicle, while the-
trapezoid portion is tightened when the shoulder is pressed inwards.

Ligaments of the scapula. — The coraco-scapular or suprascapular liga-
ment is a thin, flat band of fibres attached by its extremities to the opposite margins
of the notch at the root of the coracoid j)rocess, which it thus converts into a foramen
for the transmission of the suprascapular nerve, the corresponding artery most
commonly passing above it. This ligament is sometimes converted into bone. There
is generally a second smaller band below the nerve, close to the bottom of the notch^
on the ventral aspect of the bone.

The coraco-acromial ligament, triangular in shape, is attached by its broader
extremity to the outer edge of the coracoid process, and by the narrower to the tip
of the acromion. It consists of strong anterior and posterior bands, with a thinner
central part near the coracoid process, where it is sometimes perforated by a
prolongation of the tendon of the pectoralis minor. Its inferior surface looks down-
wards upon the shoulder- joint, the superior is covered by the deltoid muscle. From
its outer border a thin fascial layer is continued downwards over the subacromial
bursa and the shoulder-joint. The hgament forms with the coracoid and acromion
processes an arch which gives support and protection to the shoulder-joint.

Spino-glenoid ligament (fig. 19.3). — This is composed of irregular and lax fibrous
bundles which pass from the outer edge of the spine to the back of the head of the scapula,
bridging over the suprascapular vessels and nerve as they lie in the acromio-scapular notch.
It is often wanting.

THE SHOtriiDER-JOINT.

In this articulation the large and hemispherical head of the humerus is opposed
to the much smaller surface of the glenoid cavity of the scapula. The bones are
retained in position, not by the direct tension of ligaments, which would restrict
too much the movements of the joint, but by surrounding muscles and atmospheric
pressure.

The capsular ligament (fig. 192, 6) is attached to the scapula round the margin
of the glenoid cavity, and to the humerus at the place where the neck springs from
the tuberosities and shaft. It extends farthest down the humerus on the inferior
aspect, and is strongest on the superior aspect. It is so lax that the humerus
separates from the glenoid cavity as soon as its muscular connections are detached.
Above and behind, the capsule is strengthened by the tendons of the supraspinatus,
infraspinatus, and teres minor muscles, which are intimately connected with it as they
pass over the joint to reach the great tuberosity of the humerus. In front the tendon
of the subscapularis muscle comes into contact with the synovial membrane, which
is prolonged upon it through an oval opening in the capsule. The insertion of the-

1 Cleland, Journ. Anat., xviii, 277.

THE SHOULDER-JOIXT.

167

capsule is likewise interrupted opposite the bicipital groove, to give passage to the
long tendon of the biceps muscle.

The coraco-liTimeral ligament is a strong wide band extending obliquely over
the upper part of the articulation ; it springs from the root and outer border of the
coracoid process beneath the coraco-acromial ligament, and thence passes to the
neck of the humerus above the great tuberosity, being intimately connected Avith
the capsule.

Tlie coraco-humeral lig-ament represents a detached portion of the tendon of the pectoralis
minor muscle. There is sometimes a small band passing from the coracoid process with this
ligament to the upper and hinder margin of the head of the scapula, and known as the
eoraco-glcn oid I ign iiioi t.

Gleno-humeral lig-aments. — These are three bands of fibres in the inner and fore part oi
the capsule, which project towards the interior of the joint, and are best seen when the

SUPRASCAP. An

SUPRASCAP ^IGT

SUBSCAPULAHli

Fig. 193. — Right shoulder-joint openkd fkom jsehinu, to shuw Tiiii liLENo-HiMEii.vL

LioAME.Vrs. (G. D. T.)

The hinder part of the capsule lias been removed, the head of tlie humerus sawn off, and the tendon
•of the biceps divided near its origin.

articulation is opened from behind. The .viprv'ior extends from the upper end of the anterior
margin of the glenoid cavity, along the inner edge of the biceps tendon, to the inner margin
of the upper end of the bicipital groove, where there is sometimes a notch in the edge
of the articular surface : it is supposed to represent the interarticular ligament of
the hip-joint. The mhldlc springs from the glenoid margin with the foregoing, and
i.s directefi downwards and outwards to the inner side of the small tuberosity of the
humerus, forming the lower boundary of the aperture through wliich the synovial membrane
reaches the tendon of the subscapularis muscle. And the i/i/rrior. the strongest of the three,
takes a similar course from the middle of the anterior margin of the glenoid fossa to the
lower part of the neck of the humerus, where it is attached between the subscapuhins and
teres minor mus<des.

The transverse humeral lig-ament is a small band, forming a continuation of the
<»psular ligament of the sliouhler. which bridges over the bicipital groove )>etween the
tuberosities of the humerus, and thus comidetes a canal for the long tendon of the biceps
muscle. (C. fiordon Brodie, Journ. Anat., xxiv, 217.)

The glenoid ligament is a fibrous biiml, nbout two lines thick, which is fixed to
the edrre of the glenoid fossa, and thus deepens the cavity. The upper part of it is

168

THE ARTICaLATIONS OF THE UPPER LIMB.

connected with the tendon of the long head of the biceps muscle, which is also
attached at the upper end of the glenoid fossa, within the capsule of the joint.

The synovial membrane is reflected uninterruptedly from the margin of the
glenoid cavity on the inner surface of the fibrous capsule to the humerus, but its form
is complicated by its relation to the tendons of the biceps and subscapularis muscles.

Fig. 194. — View of the glenoid cavity and ligaments between

THE SCAPULA AND CLAVICLE OF THE RIGHT SIDE. -^

1, glenoid fossa, its cartilaginous surface ; 2, glenoid ligament ;
3, tendon of the biceps muscle in connection with the upper part of
the glenoid ligament ; 4, upper surface of coracoid process ; 5 and 6,
on the adjacent part of the clavicle ; 4 to 5, the conoid ; 4 to 6, the
trapezoid portion of the coraco-claviculav ligament ; 7, apex of the
acromion process ; 4 to 7, coraco-acromial ligament : 8, acromio-
clavicular articulation, which is open anteriorly, showing a wedge-
shaped interarticular fibro-cartilage attached above to the superior
acromio-clavicular ligament ; x , inferior acromio-clavicular ligament.

The long tendon of the biceps muscle, traversing the
joint in its course from the upper end of the glenoid cavity to the bicipital groove, is
enclosed in a tubular sheath, formed by a process of the synovial membrane, which
is continued down upon it into the osseo-fibrous canal between the tuberosities of the
humerus, and is thence reflected upwards lining the canal, to become continuous with

Fig. 195. — A, Section through the shoulder-joint, tendon of the biceps and bicipital groove,,'

SHOWING somewhat DIAGRAMMATICALLY THE SYNOVIAL CAVITY OF THE JOINT, &0. (Allen.

Thomson.) i
B, Outline of the same, to show the reflection of the synovial membrane over

THE TENDON.

1, outer part of the clavicle ; 2, its acromial end ; 3, cavity of the shoulder-joint close to the upper
part of the head of the scapula, where there are seen the section of the cartilages on the head of the
humerus and in the glenoid cavity, the glenoid ligament and the origin of the tendon of the biceps
muscle ; 4, glenoid ligament in the lower part of the cavity ; 5, upper part of the capsular ligament and
synovial membrane ; 6, tendon of the biceps as it passes out of the joint into the bicipital groove ;
6', 6', tubular prolongation of the synovial membrane round the tendon ; 7, reflection of the synovial
membrane on the humerus within the lower part of the capsular ligament.

the synovial membrane of the capsule in such a manner as to preseiVe the integrity
of the membrane. The bursal prolongation of the synovial membrane under the
tendon of the subscapularis muscle is of variable extent, sometimes projecting but
slightly, sometimes farming a considerable pouch on the venter of the scapula.

Subacromial bursa. — Superficial to the muscles covering the top of the joint
is a large bursa, which facilitates the movements of the upper end of the humerus
beneath the acromion process, the coraco-acromial ligament, and the deltoid muscle.

THE AETICULATIOX.S OF THE BOXES OF THE FOREARM. 169

Movements. — The shoulder-joint. bein<r a ball and socket joint, allows of angular move-
ment in all its varieties, as well as of rotation. The freedom of movement in different
dii-ections is determinai by the extent of the humeral articular surface and the lenjrth of the
capsule. In extreme positions the neck of the humerus meets the fibrous mar>rin of the
glenoid cavity on the side towards which the movement takes place, and the capsule is
stretched on the opposite side of the joint. In flexion the humenis is carried forwards and
inwards, in extension backwards and outwards, the head of the bone revolving upon an axis
which is nearly perpendicular to the centre of the glenoid cavity ; in abduction and adduction
the arm moves in directions at right angles to the foregoing, the axis being horizontal and
parallel to the surface of the glenoid fossa. The range of movement of the humerus upon
the scapula in jjassing from extreme adduction to extreme abduction is but little more than
90°. and in the direction of flexion and extension is still less. The greater freedom of move-
ment enjoyed by the arm. which can be raised from the body until it is directed nearly
vertically upwards, is due to rotation of the scapula (p. 1G5). which always accompanies these
movements of the shoulder-joint, the glenoid cavity being turned upwards when the ann is
elevated, and sinking again as the limb is depressed. In rotation the humerus revolves
about its long axis ; the whole range of the movement is about a quarter of a circle. The
arch formed by the acromion, the coracoid process, and the coi-aco-acromial ligament, lined by
the subacromial bursa, forms a sort of secondary socket in which the extremity of the
humerus, covered by the tendons inserted into the great tuberosity, revolves, and against
which it is pressed when the weight of the body is made to rest upon the arms. (C. W.
Cathcart, Journ. Anat., xviii. 211 ; Cleland. ib., 27.">.)

THE ARTICULATIONS OF THE BONES OF THE FOREARM.

The bones of the forearm are united l)y a superior and an inferior articulation
and an interosseous membrane.

In the SUPERIOR radio-ulxar articulation the head of the radius is received
into tlie small 'sigmoid cavity of the ulna and is held in position by the annular
or orbicular ligament. This ligament is a strong band of fibres attached to the

Fig. 19t). — ThK UPl'ER PART OF THK ULNA, WITH TllK ORBICULAR
LIGAMK.NT. (K. Quaiii.) ^

1, upper division of the sigmoid surface on tlie olecranon ; 2, extremity uf
the coronoid process ; 5, orbicular ligament.

ulna in front and behind, at the extremities of the small
sigmoid cavity, and forming about four-fifths of a ring which
encircles the head of the radius and binds it firmly in its situa-
tion. The external lateral ligament of the elbow is inserted
into its outer surface ; its deep surface is smooth, and is lined
by the synovial membrane of the elbow joint.

Inferior radio-ulxar articulation. — The connection
between the sigmoid cavity of the radius and the lower end
of the ulna is effected by means of a fibro-cartilage, a synovial
sac, and some scattered liL'amentous fibres in front and behind.
The triangular fibro-cartilage is a thick plate attached by its base to the border
separating the carpal from the ulnar articulating surface of the radius ; and by its apex
to a depression at the root of the styloid process of the ulna, and to the outer side of
that process. Its upper surface looks towards the ulna, its lower towards the lunar
bone, and it sef)arat(.'S the inferior radio-ulnar articulation from the wrist-joint. The
synovial sac, which is very loose, extends upwards between the radius and ulna,
and horizontally inwards between the ulna and triangular fibro-cartilage. When
the fibro-cartilage is perforated, as is frequently the case, this synovial cavity com-
municates with rliat of the wrist -joint.

'I'he interosseous membrane or ligament of the foreann is a strong fibrous
membrane, the fibres of which are directed for the most part obliquely downwards and

170 TtlE AETICQLATIONS OF THE UPPER LIMB.

inwards, from the interosseous border of the radius to that of the ulna. Its superior
border is placed about an inch below the tuberosity of the radius, leaving an open
space above (hiatus interosseus) through which the posterior interosseous vessels pass.
This space is bounded above by the oblique ligament, a flattened bundle of fibres

Fig. 197.— The lower parts of the radius and ulna, with the

TRIANGULAR FIBRO-CARTILAGE CONNECTING THEM. (R. Quain.) |

1, ulna ; 2, its styloid process ; 3, radius ; 4, articular surface for
the scaphoid bone ; 5, that for the lunar bone ; 6, lower surface of
the triangular fibro-cartilage ; * *, a piece of whalebone passed be-
tween the fibro-cartilage and the ulna.

directed downwards from the outer part of the tuberosity
of the ulna, to be attached to the radius close below the
tuberosity : it varies much in size, and is frequently
wanting. Other small bundles of fibres, having the
same direction as the oblique ligament, are often to be

found at intervals, decussating with the fibres of the interosseous ligament on.

its posterior surface.

Movement of th.e radius on the ulna. — The disposition of the annular ligament allows
the head of the radius to rotate freely within it, while the lower end of the radius, being-
bound by the triangular fibro-cartilage to the styloid process of the ulna, undergoes, in
addition to the rotation, a movement of circumduction round that point, by which the hand
is brought into the prone or the supine position. Thus in pronation and supination the
radius describes a part of a cone, the axis of which extends from the centre of the head of
the radius to the styloid process of the ulna. The range of movement between the radius and
ulna is rather less than 180°. Accompanying the movement of the radius in the pronation
and supination of the hand, there is generally a less extensive movement of circumduction on
the part of the ulna in a direction opposite to that in which the lower end of the radius
travels. The circumduction of the ulna is produced by a slight degree of flexion or extension,
together with a corresponding lateral movement, having their seat in the articulation of the
elbow, and is not accompanied by any appreciable rotation of this bone. (J. Heiberg-, " Ueber
die Drehungen der Hand," 1884, and Journ. Anat., xix ; T. Dwight, Journ. Anat., xix ; C. W.
Cathcart, Journ. Anat., xix.)

THE ELBOW-JOINT.

The lower extremity of the humerus is in contact with the ulna and radius at
the elbow, and forms with them a hinge-joint. The great sigmoid cavity of the
ulna articulates with the trochlea of the humerus, so as to admit of flexion and
extension ; while the cup-shaped depression on the head of the radius can in addition
turn freely on the rounded capitellum. In the sigmoid cavity the articular
cartilage is usually wanting over a narrow area which extends across a central
constriction produced by a marginal notch on each side between the olecranon and
the coronoid process. The fibrous capsule surrounding the joint is thickened on the
two sides, forming strong lateral ligaments, and the thinner portions in front and
behind are known as the anterior and posterior ligaments. The orbicular ligament
of the superior radio-ulnar articulation, which has already been described, is also a
part of this capsule.

The internal lateral ligament, triangular in shape, consists of anterior and
posterior thickened bands, and an intermediate thinner part. The anterior band
springs from the lower and fore part of the internal condyle of the humerus, and is
inserted into the coronoid process, along the inner margin of the sigmoid cavity.
The posterior part, broader and stronger, passes from the under and back part of
the condyle to the inner border of the olecranon ; and the intermediate fibres are

THE elbow-joi^;t.

171

connected with a small transverse band, which brid<j,es over the nctch between the
olecranon and the coronoid process.

The external lateral ligament, intimately connected with the tendinous attaoh-
jnent of the extensor muscles, is shorter and narrower than the internal. It is attached

Fig. 198. — LiGAMEKTs OF THE ELBOW-JOINT. (Alleii Thoiiison. ) i

A, from the outer side and behind ; B, from t!ie front ; C, from tlie inner side and behind. 1,
internal lateral ligament ; L', external lateral ; 3, tiie middle strongest part of the anterior ligament ;
4, orbicular ligament ; 5, posterior ligament, represented as wrinkled from relaxation in extension. In
these figures the oblique ligament and ujiper part of the interosseous membrane are also repiesented
below the elbow-joint.

Fig. 199. — Sagittal section of the elbow-joint through the great

SIGMOID CAVITY OF THE ULNA AND THE TROCHLEAR SURFACE OF THE

HUMERUS. (Allen Thomson. ) I

1, cut surface of the humerus : 2, that of the ulna ; 3, posterior part,
and 4, anteri< r part of the synovial cavity of the joint ; [>, orbicular liga-
ment ; 6, tendon of the biceps muscle ; 7, is at the lower end of the oblique
ligament.

superiorly to a depression below the external condyle of the
humerus, and inferiorly becomes blended with the orbicular
lij^ament, on the surface of which its fibres can be followed
forwai'ds and backwards to the extremities of the small sigmoid
cavity of the ulna.

The anterior ligament consists of a thin sheet of fibres,
strongest in its middle part, extending downwards from above
the coronoid and radial fossai of the humerus to the coronoid
process of the ulna and the orbicular ligament. It is covered,
except at its outeiTiiost part, by the brachialis aiiticus
muscle, which is closely attached to it near the coronoid process.

The posterior ligament, ^•eI•y thin and weak, consists of loose and irregular
fibres passing transvers(;ly across tlic olecranon fossa of the humerus, and from the
sides of that fossa to the olecranon ])rocess, thus c(»mpleting the capsule of the joint
Ixihind. Externally a rathei' sti'onger Ijand extends frcnn a slight depression behind
the ca{)itellum to the posterior border of the small sigmoid cavity of the; ulna. The

172 THE ARTICULATIONS OF THE UPPER LIMB.

posterior ligament is supported, and drawn up during extension of the joint, by the
triceps muscle which is closely adherent to it near the insertion into the ulna.

The synovial membrane extends upwards on the humerus so far as to line
the fossse for the coronoid and olecranon processes, and is loose and vascular in the
latter positions. It is also prolonged round the neck of the radius, and lines the
annular ligament. A small crescencic fold projects between the marginal part of
the head of the radius and the capitellum. Between the posterior ligament
and the synovial membrane is a mass of fat projecting into the olecranon fossa,
and two smaller pads are placed beneath the anterior ligament over the coronoid
and radial fossse.

ISIovements. — Flexion and extension are the chief movements which take place between
the humerus and ulna ; and in the perfect limb these are arrested, flexion by the meeting of
the soft parts of the arm and forearm, extension by the tightening' of the ligaments and
muscles on the front of the joint, before the coronoid and olecranon processes meet the bottom
of their respective fossse on the humems. The movements take place upon an axis which is
inclined at an angle of about 84° with the shaft of the humerus above and that of the ulna
below, so that while in the extended position of the joint these bones form an obtuse angle
open outwards, they are placed nearly opposite one another when the elbow is bent.^ The
inner Kp of the trochlea, being prominent in front, forms an expansion which corresponds to
an inward projection of the coronoid part of the ulnar surface ; while the outer lip of the
trochlea, being enlarged at the upper and back part, forms a surface which is only in use in
complete extension, and which then corresponds to a surface on the outer aspect of the
olecranon, which comes into contact with no other part of the humerus. Owing to a slight
degree of incongruence, the surface of the sigmoid cavity and the opposed portion of the
trochlear surface of the humerus are not in accurate contact over their whole extent, and a
very limited amount of lateral motion on the part of the ulna is allowed. In flexion and
extension the radius moves by its cup-shaped head upon the capitellum, and on the groove
between that eminence and the trochlea by a ridge internal to the cup. It is most completely
in contact with the humerus in the position of semi-flexion and semi-pronation.

THE WRIST-JOINT AND ARTICULATIONS OF THE CARPUS.

The EADio-CARPAL ARTICULATION, orwrist- joint, is formed between the radius and
triangular fibro-cartilage above, and the scaphoid, lunar and pyramidal bones below.
The superior surface is concave both transversely and from before backwards ; the
inferior surface is correspondingly convex, and is prolonged farther down upon the
carpal bones behind than in front. The articular surface of the radius is subdivided
into two parts by a linear elevation ; an outer, triangular, for the scaphoid, and an
inner, quadrilateral, which, together with the triangular fibro-cartilage, corresponds
to the lunar bone. The small articular surface of the pyramidal is in most cases in
contact with a portion of the capsule of the joint. The latter is rather loose, and is
divided into two lateral, anterior and posterior ligaments.

The internal lateral ligament is a rounded cord passing downwards from
the styloid process of the ulna to the pyramidal bone, and by its anterior fibres to
the pisiform bone.

The external lateral ligament extends from the styloid process of the radius-
to a depression on the scaphoid bone between the radial articular surface and the
tuberosity.

The anterior ligament, broad and membranous, consists partly of fibres which
have a nearly transverse direction, partly of others which diverge as they descend
fi'om the anterior border of the radius to the scaphoid, lunar, and pyramidal bones ;
some of them are continued to the os magnum. On the inner side a strong bundle
springs from the root of the styloid process of the ulna and passes to the pyramidal
and lunar bones.

1 Braune and Kyrklund, Arch, f, Anat., 1879.

THE WRIST-JOINT AND ARTICULATIONS OF THE CARPUS. 173

The posterior ligament extends obliquely downwards and inwards, from the
extremity of the radius to the posterior surface of the first row of the carpal bones,
especially the pyramidal bone ; its fibres are prolonged some distance on the surface
of the carpal bones.

The synovial membrane is simple and lines the ligaments between the articular
surfaces.

The carpal articulatioxs.— The bones of the carpus, the pisiform excepted,
are so arranged in two rows, that while only slight movement can take place between
the members of each row, a considerable amount of movement is possible between
the two rows. The surface presented by the first row to the second is concave both
transversely and from before backwards in the greater part of its extent, but in its
outer part it is formed by the convex part of the scaphoid bone. The opposing
surface of the second row is concavo-convex from without inwards, the concavity

A B

Fig. 200, A. — Dorsal view of the ligaments of the wrist- joint, and of the carpal and
CARPo-METACARPAL ARTicfLATiuKS. (Allen Thoiiisoi!, after Aniold. ) -A

], lower part of the ulna; 2, external lateral ligament of the wrist-joint ; '-i, internal ; near it
•leKcending obliquely to 6, from the radius, the <lorsal radio-carpal ligament ; 4 to 5, dorsal ligaments of
the first row ; 4, is on the scaphoid, o, on the lunar bone ; 6, pj'raniidal bone ; 7, trapezium ; 8,
trapezoid ; 9, os magnum ; 10, unciform ; 11 to 15, metacarpal bones ; 7 to 8, 8 to 9, and 9 to 10,
dorsal ligaments of the second row of cai^pal bones ; 4 to 8, 4 to 9, 5 to 9, and others, dorsal ligaments
between the first and second row ; 8 to 12, 9 to 13, and others, dorsal ligaments from the second row
to the metacarpal bones ; between the metacarjjal bones, from 12 to 15, the dorsal intermetacarpal
ligaments.

Fig. 200, B.

-Palmar view of tiii; ligaments op the wrist-joint, and of the carpal and

CARPO-METACARPAL ARTICULATIONS. (Allen TllOmsOn. ) A

The anterior radio-carpal ligament has been removed : 1, anterior ligament of the lower radio-uhiar
articulation ; 2, external, and 3, internal lateral ligament of the wrist-joint ; 4, scaphoid bone ; 5,
lunar ; 6, pyramidal ; 7, pisiform, with the tendon of flexor caijji ulnaris attached ; 4 to 5, and 5 to C,
palmar ligaments of the first row ; 8, external laleral ligament between the first and second rows of
carpal bones ; 9, trapezium (the traijezoid is not :iumbered) ; 10, os magnum ; 11, hook of the unciform
bone ; 9 t^j 10, 10 to 11, and others, ijalmar ligaments of the second row ; 4 to 10, and tj to 10, some of
the palmar ligaments uniting the two rows, converging on the os magnum ; 7 to 1], pisi-uncinate
ligament ; 7 to 16, jjisi-metiicarpal ligament ; 12, external ligament of the first carpo-mctacarpal
articulation ; 13, 14, 15, IG, the proximal ends of the seconil to the fifth metacarpal bones, on whicli
the i>almar transverse ligaments are shown.

being fonned by the trapezium and trapezoid, the convexity by the os magnum and
unciform bone

Jn the transverse carpal articulation the two rows of carpal bones are
united by dorsal, palmar, and lateral ligaments. The (al/'/a/ Ivjamimls are placed

174

THE ARTICULATIONS OF THE UPPER LIMB.

one at the radial, the other at thie ulnar border of the carpus ; the former connects
the scaphoid bone with the trapezium, the latter the pyramidal with the unciform.
The dorsal ligamejiis consist of fibres passing in various directions ; the pcdmar
ligaments are chiefly composed of fibres converging towards the os magnum.

The bones of the first row, the pisiform bone excepted, are united by inter-
osseous and by dorsal and palmar ligaments. The interosseous ligaments, placed on
the* sides of the lunar bone on a level with its superior surface, connect it with the
scaphoid and pyramidal bones, thus completing the inferior wall of the radio-carpal
joint. The dorsal and palmar ligaments extend transversely on the dorsal and palmar
surfaces from the scaphoid bone to the lunar, and from the lunar to the pyramidal.

The bones of the second row are connected by similar means. The dorsal
.and palmar ligaments pass transversely between the contiguous bones. The inter-

Fig. 201. — Coronal section of the inferior radio-ulnar,

RADIO-CARPAL, INTERCARPAL, AND CARPO-METACARPAL AR-
TICULATIONS. (Alleu Thomson. ) ^

1, triangular fibro-cartilage ; 2, placed on the ulna, points
to the synovial cavity of the inferior radio-ulnar articulation ;
3, external lateral, and 4, internal lateral ligament, and be-
tween them the synovial cavity of the wrist ; 5, scaphoid
bone ; 6, lunar ; 7, pyramidal ; 8, 8, upper portion, and 8', 8',
lower portion of the general synovial cavity of the intercarpal
and carpo-metacarpal articulations ; between 5 and 6, and 6
and 7, the interosseous ligaments are seen separating the carpal
articular cavity from the wrist-joint ; between the four carjoal
bones of the lower row, and between the magnum and scaphoid,
the interosseous ligaments are also shown ; the upper division
of the synovial cavity communicates with the lower between
10 and 11, and between 11 and 12; x, marks one of the
three interosseous metacarpal ligaments ; 9', separate synovial
cavity of the first carpo-metacarpal articulation ; 13, first, and
14, fifth metacarpal bone.

Note. — It is to be observed that in this figure, and in
others of a like kind which represent the joint-cavities, the
white or black lines indicating the synovial membranes are, for
the sake of clearness, generally represented as jjassing over the surfaces of the articular cartilages,
although this is not the case in nature. These lines therefore must be held to represent merely the
-whole continuity of the articular or, as they are often called, the synovial surfaces.

osseous ligaments are generally three (but sometimes only two) in number, a strong
ligament being placed between the os magnum and unciform bone, another between
the trapezoid and trapezium, and a slender ligament between the os magnum and
trapezoid. A small interosseous ligament is also found sometimes between the os
magnum and the scaphoid (fig. 201).

The synovial cavity of the carpal articulations is extensive and complicated.
Passing between the two rows of carpal bones, it sends upwards two processes
between the three bones of the first row, and downwards three between the four
bones of the second row. It is farther continued below into the inner four carpo-
metacarpal and three intermetacarpal articulations.- In some rare cases there is
■continuity with the synovial cavity of the wrist- joint, by deficiency of one of the
interosseous ligaments between the upper carpal bones.

The pisiform bone is articulated with the pyramidal bone by a thin fibrous
-capsule, lined by synovial membrane. Inferiorly, two strong bands descend from
it, the pisi-uncinate ligament to the hook of the unciform bone, and the pisi-meta-
■carpal ligament to the base of the fifth metacarpal, and sometimes also to other
metacarpal bones ; superiorly it receives the tendon of the flexor carpi ulnaris
muscle. The synovial cavity is usually distinct, but it sometimes communicates with
■that of the radio-carpal articulation.

The anterior annular ligament of the wrist is a strong and thick band,

CARPO-METACARPAL AND INTERMETACARPAL ARTICULATIONS. 175

which extends from the prominences made by the trapezium and scaphoid bone on
the radial side of the carpus, directly across to the pisiform bone and unciform pro-
cess, and converts the transverse arch of the carpus into a ring through which the
flexor tendons of the digits pass into the hand.

The posterior annular ligament, placed at the back of the wrist, is only a
thickened part of the aponeurosis of the forearm. It extends from the lower part of
the radius, at its outer border, to the inner part of the pyramidal and pisiform bones,
and serves to bind down the extensor tendons.

THE CAEPO-METACARPAL AND INTERMETACARPAL ARTICULATIONS.

The four inner metacarpal bones are bound together at their distal extre-
mities by fibres passing between the palmar ligaments of the metacarpo-phalangeal
articulations, and constituting the transverse metacarjoal ligament. At their proximal

Fig. '202. — General view of the articulations of the

WRIST AND HAND FROM BEFORE. -3-

1, lower part of the interosseous membrane ; 2, and from
that point across the lower end of the radius, the anterior
radio-carpal ligament ; 3, scaphoid bone ; 4, pisiform ; 5, tra-
pezium ; 6, unciform ; 7, os magnum, with most of the deeper
ligaments uniting these bones : I, first metacarpo-phalangeal
articulation with its external lateral ligament ; II to V, trans-
verse metacarpal ligament ; iu the several interphalangeal arti-
culations of the lingers the lateral ligaments are shown ; in the
thumb the e.\ternal only is visible.

extremities they are united to one another and to
the carpal bones iu articulations, the common syno-
vial lining of which is derived from that of the
intercarpal joint. In these articulations the four
metacarpal bones are bound together by three
dorsal, and three palmar, and by strong interos-
seous ligaments. The second, third and fourth
metacarpal bones are united to the carpus by dorsal
ligaments, of which each bone receives two, viz., the
second from the trapezium and trapezoid, the third
from the trapezoid and os magnum, and the fonrtli
irom the os magnum and unciform, and by palmar
ligaments, one to each Ijone, but which are not so

well defined and less constant. The fifth metacarpal bone is united to the unciform
bone by a thin capsule which surrounds the articulation except on the outer side.
There is likewise an interosseous band in one part of the carpo-metacarpal articula-
tion, connecting the lower and contiguous angles of the os magnum and unciform to
the adjacent angle of the third metacarjial bone. This ligament sometimes sepa-
rates the cavity between the unciform and two inner metacarpal Ikjucs Irom the rest
of the joint.

The first metacarpal bone is articulated with the trapezium by a capsular
investment, which is thickened behind and on the outer side, and is lined by a dis-
tinct synovial membrane.

176

THE ARTICULATIONS OF THE UPPER LIMB.

THE METACARPO-PHALANGEAL AND INTERPHALANGEAL ARTICULATIONS.

The rounded head of each metacarpal bone is received into the slight hollow in
the base of the first phalanx, and the bones are maintained in position by two lateral
ligaments and an anterior ligament.

The lateral ligaments are strong bands springing from the tubercle and
depression on each side of the head of the metacarpal bone, and passing down-
wards and forwards to the contiguous margin of the phalanx. The anterior fibres
are directed almost horizontally forwards and join the palmar ligament of the
articulation.

The anterior or palmar ligament, or rather fibrous plate, occupies the
interval between the lateral ligaments on the palmar aspect of each joint ; it is a

Fig. 203. — Sagittal skction THRoacH the lower part of the radiuSj

LUNAR BONE, OS MAGNUM, METACARPAL BONE AND PHALANGES OP THE
MIDDLE FINGER, TO SHOW THE SHAPE OF THE ARTICULAR SURFACES
AND THE SYNOVIAL CAVITIES BETWEEN THESE SEVERAL BONES. (Allen

Thomson.) 3

1, synovial cavity of tlie wrist-joint ; 2, intercarpal cavity ; 3, carpo-
metacarpal cavity ; 4, metacarpo-phalangeal cavity ; 5 and 6, interphalangeal
cavities ; 4', 5', and 6', the palmar fibrous plates which are attached to the
bases of the several phalanges ; 7, indicates the place of the tendons of the
long flexor muscles ; 8, section of the anterior annular ligament ; 9, and 10,
transverse retinacula, or vaginal ligaments of the flexor tendons on the first
and second phalanges.

thick and dense fibrous structure, which is firmly united to
the phalanx but loosely adherent to the metacarpal bone. It
is continuous at each side with the lateral ligament, so that
the three form one undivided structure which covers the joint,
except on the dorsal aspect. Its palmar surface is grooved for
the flexor tendon, the sheath of which is connected to it at
each side ; the other surface, looking to the interior of the
joint, is lined by synovial membrane, and supports the head
of the metacarpal bone. In the joint of the thumb there are
two sesamoid bones, one situated at each side, which are con-
nected with its hgaments.

A synovial membrane is present in each joint, and
invests the surface of the ligaments which connect the
bones.
The interphalangeal articulations differ from the foregoing only in the shape
<of the articular surfaces (see p. 105).

fl

Movements of the wrist and fingers. — The movements taking place at the wrist have
their seat partly in the radio-cai-pal, partly in the transverse carpal articulation. Flexion is
the freest movement, but a considerable degree of over-extension is also permitted. The hand
-can also be moved laterally, and to a greater extent inwards (adduction or ulnar flexion) than
outwards (abduction or radial flexion). According to Henke and Langer both radio-carpal
and transverse carpal articulations are essentially hinge-joints, the axes of which are oblique
in opposite directions, that of the first joint extending from the styloid process of the radius
to the pisiform bone, and that of the transverse carpal joint from the tuberosity of the
scaphoid to the dorsum of the pyramidal bone. Flexion and extension are accordingly the
result of simultaneous movements in the two joints in the same direction, while abduction is
produced by flexion in the radio-carpal joint combined with extension in the transverse carpal
joint, and adduction by extension in the radio-carpal joint with flexion in the transverse
carpal joint. Side to side movement is permitted only to a very slight extent in the radio-
carpal joint. (Henke, " Handbuch der Anatomic und Mechanik der Gelenke," 1863 ; Langer,
■"' Lehrbuch der Anatomic.")

MOVEMENTS OF THE HAND AND FINGERS.

177

The kind of movement which is allowed between the several carpal and metacai-pal bones
is best illustrated by placing: the hand in such a position that the weight of the body is
rested upon the open palm. The metacarpal rang'e. which naturally is concave towards the
palm, is flattened ; and the interosseous and palmar metacarpal lijjfaments are thus tio-htened
while a slight separation of the opposed surfaces of the bones takes place : so also the palmar
carpo-metacarpal ligaments are tightened, and both palmar and interosseous ligaments of the
second range of carpal bones. The convex part of the os magnum and unciform bone, fitted
in these circumstances into the concavity of the first range, is a little wider than the part
usually in contact with it ; and thus, while the bones of the second range are separated from
the palmar- side, those of the fii-st range are pressed still more apart from the distal aspect.
The whole arrangement secures elasticity. The fourth and especially the fifth metacaipal
bones are not so tightly bound to the carpus as the second and third, and can therefore be
moved to some extent forwards (opposition), thus making the hand narrower and deei^ening
the hollow of the palm : these bones move in this way very distinctly in shutting the hand,
so that the back is then rendered more convex, and the tips of the fingers are brought more
closely together. At the interphalangeal articulations the only movements allowed are
flexion and extension, while over-extension is prevented by the ligamentous structures in front
of the joints. At the metacarpo-phalangeal articulations of the fingers abduction and adduc-
tion are also allowed, chiefly in the extended position. In the articulation of the metacarpal
bone of the thumb with the trapezium all kinds of angular movement are allowed, but owing
to the shape of the articular surfaces the movement of flexion is accompanied by a certain
•amount of rotation of the metacarpal bone on its long axis, by which the thumb is turned
towards the fingers, thus giving rise to the so-called opposition. The metacarpo-i^halansreal
articulation of the thumb allows of only a limited amount of flexion and extension.

III.— THE ARTICULATIOH'S OF THE PELVIS.

Articulatiox of the pelvis with the last lumbar vertebra. — The
fifth lumbar is united to the first sacral vertebra by anterior and posterior ligaments
of the bodies, capsular ligaments of the articular processes, ligamenta subflava of

Fig. 204. — Articulations of the

PELVIS AND HIP-JOIXT, SEEN FROM

BEFORE. The anterior half

OF THE CAPSULAR LIGAMENT OF
THE LEFT HIP-JOINT HAS BEEN
REMOVED, AND THE FEMUR RO-
TATED OUTWARDS. (Allen Thom-
son.) J

1, 1, anterior common ligament
<">£ the vertebrae passing down to the
front of the sacrum ; 2, ilio-lumbar
ligament ; 3, anterior .sacro-iliac liga-
ment ; 4, placed in the great sacro-
.sciatic foramen, points to the small
sacro-sciatic ligament ; 5, a portion
of the great sacro-sciatic ligament ;
6, anterior ligament of the symphysis
pubis ; 7, obturator membrane ; 8,
capsular ligament of hip-joint ; the
figure is placed on its ilio-femoral
band ; 9, upper part of the divided
capsular ligament of the left hip-joint
near the place of its attachment to
the border of the acetabulum ; 10,
placed on the oh pubis of the left

.side above the transverse ligament of the acetabular notch. The head of the femur is
partially from the socket, so as to show the interarticular ligament stretched from the
ligament.

withdrawn
transverse

the arches, interspinous and supraspinous ligaments, and by an intervertebral disc,
all of which are similar to those between the vertebrae above. It is also attached
to the pelvis by two other ligaments, as follows.

The lateral lumbo-sacral ligament is a variable fasciculus, passing from the

178

THE ARTICULATIONS OF THE PELVIS.

lower border of the transverse process of the last lumbar vertebra obliquely down-
wards to the lateral part of the base of the sacrum ; its fibres diverge as thej^
descend, and some of them join the anterior sacro-iliac ligament.

The ilio-lumbar ligament is a strong band passing outwards and some-
what backwards from the summit of the transverse process of the last lumbar
vertebra to the iliac crest of the hip-bone ; it is inserted into the latter above i^he
back part of the iliac fossa, where its fibres expand somewhat, so as to give it a
triangular form.

The lateral lumbo-sacral ligament represents an anterior superior costo-transverse ligament :■
the ilio-lumbar ligament is a thickening of the anterior layer of the fascia lumborum.

Aeticulations of the sacrum axd coccyx, axd of the pieces of the
COCCYX. — The sacrum and the coccyx are united by an intervertebral disc ; by an
anterior ligament, a thin layer of fibres forming a continuation of the anterior

Fig. 205. — Ligaments of the

PELVIS AND HIP-JOINT SEEN
FROM BEHIND, FROM A FEMALE

SUBJECT. (Allen Thomson. ) ^

1, ilio-lumbar ligament ; 2,
posterior sacro-iliac ligaments, the
short and the oblique ; 3, great
sacro-sciatic ligament ; 4, small
sacro-sciatic ligament ; 5, obtu-
rator membrane ; 6, posterior
ligament of symphysis pubis ;

7, 7, continuation of supraspinous
ligament from the lower lumbar
vertebrae over the sacral spines ;

8, transverse process of last lum-
bar vertebra, from which the
lateral lumbo-sacral ligament is
seen descending ; 9, capsular liga-
ment of the hip-joint ; the figure
is placed on the ischio-capsular
band.

common ligament of the
vertebrae ; by a posterior
lifiament, more strongly
developed, which descends from the margin of the inferior orifice of the sacral
canal to the back of the coccyx ; by inter articular ligaments between the cornua
of the two bones ; and by lateral ligaments, passing on each side from the lower
lateral angle of the sacrum to the transverse process of the first piece of the coccyx.
The pieces of the coccyx, so long as they remain separate, are connected by fibro-
cartilaginous discs and prolongations of the above-mentioned anterior and posterior
ligaments.

A distinct cavity is stated by Cruveilhier to be present in the centre of the disc between
the sacrum and coccyx in those cases in which the coccyx is freely moveable. This is in con-
formity with the observations of Luschka on the other intervertebral discs. After middle
life, the union between the pieces of the coccyx is usually ossific ; and the coccyx may then
also become united to the sacrum. The union of the coccyx is less frequent in the female
than in the male ; and the mobility of the coccyx seems to increase during pregnancy.

From the tip of the coccyx a fibrous band passes to the integument, which is often,
especially in the infant, marked by a depression (fovcola coccygea) at this spot.

The sacro-iliac articulation is formed between the auricular surfaces of
the sacrum and ihum, which are covered each with a layer of cartilage, that on the
sacrum being the thicker, and closely applied together,, but are not usually directly

THE SACRO-SCIATIC LIGAMENTS.

179

united. In some cases, however, the two surfaces are connected in part of their
extent by fine transverse fibres ; while on the other liand, it not unfrequently
happens, especially in advanced life, that the surfaces become rough and irregular,
and are separated by small spaces containing glairy fluid. The bones are united by
anterior and posterior sacro-iliac ligaments, and the articulation receives additional
support from the great and small sacro-sciatic ligaments.

The anterior sacro-iliac ligament consists of thin irregular fibres passing
between the sacrum and hip-bone on their iliac and pelvic surfaces.

The posterior sacro-iliac ligament consists of a large number of strong
irregular bundles extending from the rough space above the auricular surface of the
ilium, downwards and inw^ards to the depressions on the back of the lateral mass of
the sacrum. A superficial band, passing nearly vertically downwards from the
posterior superior iliac spine to the third and fourth pieces of the sacrum, is
distinguished as the Jonrj or oblique sacro-iliac ligament.

The sacro-sciatic ligaments. — The posterior or great sacro-sciatic
ligament, broad and triangular, assists in bounding the lower aperture of the pelvis.

Fig. 20tl. — Right half of a female pelvis, seen

FROM THE INNER SIDE. (Alleu ThomSOli.) |

1, supraspinous ligament descending to the sacrum
from 2, 2, the himbar spinous processes ; 3, 4, lumbar
and sacral spinal canal ; 5, placed on the ilium above
the anterior sacio-iliac ligament ; 6, placed in the great
sacro-sciatic foramen, points to the small sacro-sciatic
ligament ; 7, great sacro-sciatic ligament, with 7', its
falciform process ; 8, aperture where a portion of the
wall of the cotyloid cavity has been removed, so as to
give a view from the inside of the head of the femur ;
9, interarticular ligament put upon the stretch, the
femur being partially flexed and adducted ; 10, inner
part of the capsular ligament relaxed ; 11, shaft of the
femur.

Its base is attached to the posterior inferior
iliac spine and to the side of the sacrum and
coccyx ; while its apex is fixed along the
inner margin of the ischial tuberosity, where
it expands somewhat, and sends forwards
along the margin of the ischial ramus a fal-
ciform process the border of which is con-
tinuous with, and forms the inferior attachment of, the obturator fascia. Home of
the superficial fibres of the ligament are continued over the tuberosity into the
tendon of the long head of the biceps muscle.

The anterior or small sacro-sciatic ligament, much shorter and thinner
than the preceding, in front of which it lies, is also triangular in form, and is
attached by its base to the side of the sacrum and coccyx, where its fibres are
united with those of the great ligament, and by its apex to the spine of the ischium.
The deep surface of this hgament is blended with the coccygeus muscle.

The icreat sacro-sciatic ligament represents the proximal portion of the tendon of the
long hea^l of the bicep.s muscle, which has formed an attachmtjnt to the ischial tuberosity.
The small nacro-sciatic ligament is formed by fibrous degeneration of the superficial part of
the coccygeus muscle.

Foramina, lietween the great sacro-sciatic ligament and the hip-bone is a
large space subdivided by tlie small sacro-sciatic ligament. The part which lies
above this ligament is named the tjreat sacro-scialic foramen. It transmits the

180 THE ARTICULATIONS OF THE PELVIS.

piriformis muscle, the gluteal, sciatic, and pudic vessels and nerves, and the nerves
to the obturator internus and quadi-atns femoris muscles. The part between tlie
greater and lesser sacro-sciatic ligaments, much smaller and bounded in front by
the smooth surface between the spine and tuberosity of the ischium, is the small
sacro-sciatic foramen, through which pass the obturator iuternus muscle, the pudic
vessels and nerve, and the nerve to the obturator internus.

The PUBIC ARTICULATION, or symj)Jiysis pubis, is the connection of the pubic
bones in front, and is effected by an interpubic disc and ligaments. The interjmUc
disc consists of a layer of cartilage on each side, closely adherent to the bony sur-
faces, and an intermediate stratum of fibrous tissue and fibro-cartilage. The inter-
mediate layer is thicker in front than behind, and generally contains a fissure
towards the upper and back part, which sometimes extends through the whole depth
of the articulation (fig. 207). The ligaments are named anterior, posterior,
superior, and inferior. The anterior puUc ligament is of considerable thickness ; it
consists of deep fibres passing transversely between the bones at the front of the
disc, and superficial, oblique, interlacing fibres derived mainly from the tendons of
the obliquus externus and rectus muscles of the abdomen, as well as of the super-
ficial adductors of the thigh. The superior and posterior ligaments consist of only
a %-ss fibres on the upper and back parts of the articulation. The inferior or
suhpuMc ligament, thick and triangular, is attached to the inferior rami of the pubic
bones, giving smoothness and roundness to the subpubic angle, and forming part
of the outlet of the pelvis.

The fissure in t.lie interpubic disc appears to be formed during- life by the softening and
absorption of the fibro-cartilage. It is not usually found before the seventh year, it increases
in extent with advancing age, and is more constant and of larger size in the female than in
the male. Its greater development in the female sex may be in pai-t due to the pressure
exerted upon the joints of the pelvis during parturition, but it is not a regular accompaniment
or a direct consequence of pregnancy.

The obturator membrane, or ligament, is a fibrous septum attached to the
border of the thyroid foramen, which it closes, except at the obturator groove, where
a small oval canal is left for the obturator vessels and nerve. The membrane is
fixed accurately to the bony margin at the outer side of the foramen, but to the
posterior surface at the inner side. The obturator muscles are attached to its
surfaces.

Movements and meclianism.. — In ordinary circumstances there is very little movement
allowed between the bones of the pelvis. In the erect posture the sacrum is inclined so much
backwards that none of the advantage of the key-stone of an arch is obtained by the tapering
of its form from base to apex. It is only by the sinuosities of its auricular surfaces that it
directly presses on the hii3-bones ; and as the width of the bone rather diminishes towards the
dorsal surface, the principal strain is borne by the posterior sacro-iliac ligaments, from which
the sacrum is in great measure suspended (see fig. 207). As the base of the sacrum, in the
upright posture, projects forwards much beyond the auricular surface (cf. fig. 14 and 18), this
bone will necessarily have a disposition to rotate about the place of support under the
influence of the pressure of the superposed column, the upper extremity tending to sink and
the lower extremity to rise. This tendency is restrained by the sacro-sciatic ligaments, which
tie the lower end of the sacrum to the ischium. The ilio-lumbar ligament acts similarly in
supporting the base of the column, and it also serves to prevent the fifth lumbar vertebra
from slipping forwards over the oblique base of the sacrum. The space which might be
gained by the small amount of movement allowed between the bones of the pelvis iii the
ordinaxy state is increased during partuiition in this way, that the fore part of the sacrum
being pressed backwards, the wider part of the wedge formed by this bone is forced
farther between the hip-bones so as to separate them to a greater degree, and thus to
increase the capacity of the pelvis. It is thought also by some that during pregnancy a
slight amount of separation may occur at the symphysis pubis from relaxation of the con-
necting parts.

THE HIP-JOIXT.

181

IV.— THE ARTICULATIOlSrS OF THE LOWER LIMB.

THE HIP-JOINT.

This is a ball and socket joint, in which the globular head of the femur is re-
ceived into the acetabulum or cotyloid cavity of the hip-bone. The articular
portion of the acetabulum is a horseshoe-shaped, cai'tilage-covered surfa-^e, broader
above and behind than in front, and folded round the fossa acetabuli which, extend-
ing from the cotyloid notch to the bottom of the cavity, is occupied by adipose
tissue covered with synovial membrane, the so-called synovial or Haversian gland.
The articular surface of the femur presents a little behind and below its centre a pit
in which the interarticular ligament is attached.

The cotyloid ligament forms a thick fibro-cartilaginous ring round the
margin of the acetabulum, increasing the depth of its cavity, and bridging over

Fig. 207. — Transverse oblique section of the pelvis and hip-joint, cutting the fikst sacual

VERTEBRA AND THE SYMPHYSIS PUBIS IN THEIR MIDDLE, FROM A MALE SUBJECT OP ABOUT NINE-
TEEN YEARS OF AGE. (Allen Tbomson.) ^

1, first sacral vertebra ; 2, ilium ; 3, posterior sacro-iliac ligament ; 4, cavity of the sacro-iliac
articulation ; 5, anterior sacro-iliac ligament ; 6, small sacro-suiatic ligament ; 7, great sacro-sciatic
ligament ; 8, placeil in front of the .symphysis jJubis, in the cut surface of which the small incUiuu
cavity, the adjacent cartilaginous plates, and the anterior and jjosterior ligamentous tilircs are shown ;
'J, lower part of the obturator membrane ; 10, cartilaginous surface of the cotyloid cavity, tlirough the
middle of which the incision passes transversely, dividing the interarticular ligament and the fat in the
fossil acetabuli ; 11, cotyloid ligament ; 1'2, interarticular ligament coiinci^ted with the transverse jjart
of the cotyloid ligament ; 13, placed on the cut surface of the iioad of the left ffuiur near the depresssion
where the interarticular ligament is attached ; 14, 14', uiipcr and lower parts of tlio capsular ligament.

the deficiency in its border. Its external surface is in contact with the capsular
ligament ; the internal closely embraces the head of tlie ieinur. and both are
covered by the synovial membrane. Its fibres do not run i)arallel to the circum-

N 2

182 THE ARTICULATIONS OF THE LOWER LIMB.

ference of the cotyloid cavity, but pass obliquely from without inwards over its
maro'in, one extremity being attached to the outer, the other to the inner surface.

At the cotyloid notch the fibres of the ligament are continued from side to side,
so as to render the circumference complete, and deeper transverse fibres are super-
added, from which circumstance, as well as from being stretched across from one
maro'in of the notch to the other, this part is called the transverse ligament. Beneath
it an interval is left for the admission of the articular vessels.

The interarticular or round ligament (ligamentum teres) is a variable fas-
ciculus surrounded by synovial membrane, attached by one extremity, which is
round, in the fossa on the head of the femur ; by the other, which is broad and
flat, to the transverse Kgament and the margins of the cotyloid notch, the strongest
fibres passing to the ischial border. It rests on the fat in the fossa acetabuli.

The capsular ligament surrounding the joint is attached above to the margin
of the cotyloid cavity, and below to the neck of the femur. At its cotyloid attach-
ment the capsule arises, above and behind, from the bony margin outside the
attachment of the cotyloid hgament, having its inner surface in close contact with
that lio-ament ; in front it arises from the outer aspect of the cotyloid ligament near
its base, and at the notch it is similarly attached to the transverse ligament. At its
femoral attachment the capsule extends anteriorly to the intertrochanteric line,
superiorly to the root of the great trochanter, posteriorly and inferiorly to the
junction of the middle and external thirds of the neck. The fibres of which the
capsule consists run in two directions, circularly and longitudinally. The circular
fibres are most distinct at the lower and posterior part of the capsule, where they are
collected into a band about half an inch in breadth, which embraces the neck of the
femur ; above and in front they spread out and become interwoven with the deeper
layers of the strongly developed longitudinal fibres, by which they are thus con-
cealed. The longitudinal fibres on the posterior aspect of the joint are almost
absent, being represented only by a few scattered fibres which support the synovial
membrane, and attach the circular fibres to the neck of the femur. In other parts
of the capsule the longitudinal fibres form thick bands, certain of which from their
greater size and strength are distinguished as accessory ligaments. The most
important of these is formed on the antero-superior aspect of the capsule and is
known as the ilio-femoral ligament (fig. 204, 8). This springs above from the lower
part of the anterior inferior iliac spine, and behind this from an impression on the
bone immediately above the margin of the acetabulum ; the fibres diverge and form
two strong bands, the inner of which passes almost vertically to the lower part of the
anterior intertrochanteric line, the outer to the upper part of the same line and the
adjacent part of the neck of the femur. Between the two bands is a thinner part of
the capsule ; but it not unfrequently happens that the division is not marked, so
that the ligament forms one flat triangular band, attached by its base to the whole
length of the anterior intertrochanteric line.-' At the lower and hinder part of the
joint, a broad and strong band of fibres, the iscMo-capsular ligament, passes from the
furrow on the ischium below the acetabulum to end in the circular fibres. In front
and below may be also found a number of scattered fibrous bundles, which converge
to the capsule from the ilio-pectineal eminence, from the obturator crest, and from
the obturator membrane, constituting the pubo-femoral ligament. Besides these
the capsule receives above other strengthening bands from the tendon of the posterior
head of the rectus femoris, and from the gluteus minimus.

From the inside of the capsule the innermost fibres are reflected upwards from

1 The outer or upper of tliese 'bands is sometimes described separately as the ilio-trochanteric
ligament ; and the whole structnre is frequently designated by surgeons the Y ligament of Bigelow.

THE KNEE-JOINT. 183

their insertion upon the neck of the femur to the urticular cartilage, forming a
surface partly level and partly raised into longitudinal folds called retinacula.

The sjmovial membrane of the joint is reflected from the neck of the femur
to the inner surface of the capsule, thence to the inner surface of the cotyloid liga-
ment and to the pad of fat in the bottom of the acetabulum, from which it is farther
prolonged as a tubular investment upon the interarticular ligament. It sometimes
communicates, through an opening in the anterior wall of the capsule between the
ilio-femoral and pubo-femoral ligaments, with a synovial bursa placed beneath the
tendon of the ilio-psoas muscle.

Movements. — The movements allowed at the hip-joint are flexion, extension, abduction,
adduction, circumduction, and rotation. Extension is limited by the anterior fibres of the
capsular ligament and the inner band of the ilio-femoral ligament : flexion, when the knee
is bent, is limited only by the contact of the thigh with the abdomen, but when the knee is
extended the movement is arrested earlier by the hamstring muscles. Abduction is controlled
by the pubo-femoral band, by the lower part of the capsule, and by the upper border of the
neck of the femur coming into contact with the margin of the socket formed by the cotyloid
ligament ; adduction by the outer band of the ilio-femoral ligament, and by the upper part
of the capsule. Rotation outwards is checked mainly by the outer part of the ilio-femoral
ligament, inwards by the ischio-capsular lig^ament, the hinder part of the capsule, and the
muscles at the back of the joint. The whole extent of the movement of rotation is less
than the sixth of a cu'cle. The interarticular ligament is put upon the stretch when the
hip is partlj- flexed, and the thigh then adducted (fig. 206) or rotated out, but it is in many
cases so slender that it can have very little influence upon the mechanism of the joint. The
ilio-femoral ligament is so strong that it is but rarely broken in dislocations of the hip, and
advantage is taken of this circumstance in attempting to reduce the displacement by
manipulation. During the swinging antero-postjrior movements of the femur, as in walking
or running, the head of the bone revolves on a horizontal axis without any tendency to
escape from the socket, but in the lateral movements and in rotation the articular surface of
the head projects beyond the margin of the acetabulum on the opposite side to that towards which
the movement is taking place. In the erect attitude a vertical line passing through the
centre of gravity of the trunk falls behind the centres of rotation in the hip-joints ; the
pelvis therefore tends to fall backwards by over-extension of the hip-joints, but as this
is prevented by the tightening of the capsule in front, the trunk is supported upon
the thigh-bones in great measure without muscular effort by virtue of this mechanism of the
joint.

THE KNEE-JOINT.

The articular surfaces of this complicated joint are the condyles of the femur and
the condylar surfaces of the tibia, with interposed fibro-cartilages, the articulating
surface of the patella, and the patellar surface of the femur. The action is mainly
that of a hinge-joint. The joint is strengthened superficially by fibrous coverings
derived from the surrounding tendons and aponeuroses. The ligamentous structures
of the joint are the following.

The internal lateral ligament, long and flat, connects the internal tuberosity
of the femur with the inner part of the shaft of the tibia, on which it descends to
beyond the level of the tubercle : some of the deeper fibres are also inserted into the
internal fibro-cartilage and the margin of the inner tuberosity. The tendon of the
semimembranosus muscle passes to its insertion beneath the posterior border of the
ligament, to which it sends a few fibres ; and below the inner tuberosity the lower
internal articular vessels are placed between the ligament and the bone.

The external lateral ligament is a rounded cord, which extends from the
external tuljcrosity of the femur to the head of the fibula. Its internal surface lies
upon the tendon of the popliteus muscle and the inferior external articular vessels.
The tendon of the biceps flexor cruris muscle is divided into two by this ligament,
and between the ligament and the tendon there is frequently a synovial bursa.
Farther back is another less constant band, the short exkrnal laleral li(jument, which
springs from the external condyle of the femur in connection with the outer head of
the gastrocnemius, and terminates below on the styloid process of the fibula.

184

THE ARTICULATIONS OF THE LOWER LIML.

The internal lateral ligament is derived from the tendon of the adductor magnns muscle ;
the external represents the detached femoral origin of the peroneus longus (Sutton).

The posterior ligament is broad and membranous, and passes from the upper
edge of the intercondylar fossa of the femur to the posterior margin of the head of
the tibia. It is in great part formed by an expansion from the tendon of the semi-
membranosus, which is directed upwards and outwards towards the external condyle
of the femur and the outer head of the gastrocnemius muscle.

The ligamentuni patellse, or infrapatellar tendon of the quadriceps extensor
cruris muscle, is a strong flat band, attached above to the apex and lower border of

Fig. 208, A. — Eight knee-joint, from the inner side and anteriorly. (Allen Thomson.)

1, tendon of the rectus muscle near its insertion into the patella ; 2, insertion ef the vastus internus
into the rectus tendon and side of the patella ; 3, ligamentum patella descending to the tubercle of the
tibia ; 4, capsular fibres forming a lateral ligament of the patella prolonged in part from the insertion
of the vastus internus downwards towards the inner tuberosity of the tibia ; 5, internal lateral ligament ;
6, tendon of the semimembranosus muscle. (After Arnold. )

Fig. 208, B. — Right knee-joint from behind. (Allen Thomson. )

1, insertion of the tendon of the adductor niagnus ; 2, origin of the inner head of the gastrocnemius
muscle ; 3, outer head of the same ; 4, external lateral ligament ; 5, tendon of the popliteus muscle ;
6, part of internal lateral ligament ; 7, tendon of the semimembranosus muscle ; 8, posterior ligament,
spreading outwards from the tendon ; 9, expansion of the popliteal fascia downwards from the same,
represented as cut short ; 10, on the head of the fibula, marks the posterior superior tibio-fibular
ligament; 11, upper part of the interosseous membrane with the foramen at the upper end for the
anterior tibial vessels.

the patella, and below to the tubercle of the tibia. Between the tibia and the liga-
ment, near its insertion, is placed a synovial bursa.

The crucial ligaments, placed in the centre of the joint, pass from the sides of
the intercondylar fossa to the spaces in front of and behind the spine of the tibia.
They decussate somewhat like the lines of the letter X. The anterior or external
ligament is fixed by its lower extremity to the inner part of the depression before the
spine of the tibia, and by its upper extremity it is inserted into the inner and hinder
part of the external condyle of the femur ; hence its direction is upwards, back-

THE KNEE-JOI^T.

185

■wards, and outwards. The jjosterior or internal ligameni, stronger but shorter thau
the anterior, is attached below to the floor of the popliteal notch of the tibia, and
above to the lower part of the outer surface of the internal condyle, as well as to the
adjacent fore part of the intercondylar fossa of the femur ; its fibres are directed
upwards and a little forwards aud inwards.

The semilunar fibro-cartilages are two crescent-shaped plates, placed on
the ariiculatinu,- surfaces of the head of the tibia, and interposed between these
and the condyles of the femur. They have each a smooth free surface above
and below, and a convex border, which is thick, while the concave border is thinned
to a fine edge ; and the part of the articular surface of the tibia within the concave

Fi°'. 209 A.— The knee-joint, opened from before, to show the crucial ligaments and

°' " ' ' SEMILUNAR FIBRO-CARTILAGES. (Allen ThomSOll. ) \

1 external 2, internal semilunar fibre- cartilage ; 3, on the outer condyle of the feuiur, points to
the anterior crucial ligament ; 4, placed on the line separating the patellar surface from the inner
condylar surface of the femur, points to the posterior crucial ligament ; 5, transverse ligament of the
semilunar fibio-cartilnges ; 6, part of the ligamentum patella; ; 7, on the head of the fibula, points to
the anterior superior tibio-fibular ligament ; 8, upper part of the interosseous membrane,, showing the
perforation for the anterior tibial vessels.

Fi". 209, B.— The knee-joint, opened from behind, so as to expose the crucial ligaments

AND SEMILUNAR FIBRO-CAKTILAGES. (Allen ThomSOn. ) J

1 internal 2, external semilunar fibro-cartilage ; 3, anterior, 4, posterior crucia. ligament;
farther up is seen the accessory band from the external semilunar fibro-cartilage ; 8 upper part of the
interosseous membrane ; 9. internal lateral ligament ; 10, placed on the head of the lib,, a, point, to
the posterior superior tibio-fibular ligament ; between the head of the fibula and the external hbro-
cartila^e (•>) is seen the surface of the tibia upon which the semilunar cartilage descends in flexion and
where a communication sometimes takes place between the synovial cavities of the knee-joiiit and of the
tibio-fibular articulation.

border of each cartilage is left uncovered. At their extremities tlicy ai-e fibrous, and
are firmly fixed to the head of the tibia, while by their circumference they are
connected with the fibrous capsule of the joint.

The internal semilunar fibro-cartilage forms about a semicircle ; its anterior
extremity is small and pointed, and is inseiled into an impression at the fore and
inner part of the hollow before the spine of the tibia ; its posterior end is attached

186

THE ARTICULATIONS OF THE LOWER LIMB.

TUBERCLE

ANT. CRUC. LIGT.
INT. FIBRO-CART.

EXT. FIBRO-CART.

Fig. 210. — Upper EXTREMITY of the right tibia,
FROM ABOVE. (Drawn by T. W. P. Lawrence.) |

In front of the outer tubercle of the spine, and
immediately external to the anterior attachment of
the external semihinar fibro-cartilage, is seen the
small facet which comes into contact with the outer
condyle of the femur in extension of the knee-joint.

to the inner edge of the hollow behind
the spine, in front of the posterior cruciid
ligament.

The external sesniliinar filbro-car-
tilage forms nearly a complete circle ; its
two extremities are fixed, one in front of,
the other between the points of the spine
of the tibia, and are so close at their in-
sertion that they may be said to be interposed between the attachments of the
internal semilunar plate. Its external border is in contact behind with the tendon of

Fig. 211. — View of the semilunar fibro-cartilages of the

RIGHT knee-joint, FRuM ABOVE, WITH THE CUrciAL LIGA-
MENTS DIVIDED, AND THE LIGAMENTUM PATELL.E TURNED

FORWARDS. (Allen Thomson.) I

FIBRO-CART.

1, ligamentum patella ; 2, inner, 3, outer fibro-cartilage ;

4, placed on the tibia in front of the transverse ligament ;

5, cut end of the anterior crucial ligament ; 6, cut end of the
posterior crucial ligament, from which a band is seen descend-
ing to the outer fibro-cartilage ; 6', tibial attachment of the
posterior crucial ligament ; 7, head of the fibula ; 8, cartilage-
covered surface of the tibia, which extends for some way

downwards towards the tibio-fibular articulation.

much in diflFerent bodies,

Fig. 212. — Sagittal section of the left knee-joint, seen
FROM THE OUTER OR LEFT SIDE. (Allen Thomson.) I

The section is made somewhat obliquely a little to the outside
of the middle, so as to preserve entire the crucial ligaments
with their attachments : it is from a young subject of eighteen
or nineteen years. 1, 1, the upper portiou of the synovial cavity
extending upwards between the extensor tendon and the femur ;
1', an aperture made into the posterior portion of the synovial
cavity ; 2, 2', mucous ligament ; 3, ligamentum imtellse ; 2', 3,
infrapiatellar synovial fatty cushion ; 4, bursa above the inser-
tion of the ligamentum patellte into the tubercle of the tibia ;
5, 5', anterior crucial ligament ; 5', points also to the internal
semilunar fibro-cartilage within the joint ; 6, lower part of the
posterior crucial ligament, the npper part of which is towards
2 ; 6', the accessory band joining the external semilunar fibro-
cartilage, which is cut short ; 7, spine of the tibia.

the popliteus muscle, and is therefore separated by
this from the fibrous capsule. From the posterior
extremity of this fibro-cartilage a ligamentous band
ascends, to be attached to the inner condyle of the
femur in connection, either in front or behind, with
the posterior crucial ligament.

Transverse ligament. — Towards the front of
the joint the convex borders of the semilunar fibro-
cartilages are connected by a slight transverse
band which receives this name. Its thickness varies
and it is sometimes wanting.

THE KNEE-JOINT.

187

Capsular membrane. — Under this name is described the fibrous membrane
■which invesi;- the joint in the intervals lietween the stron^-er bands which have been
named lig-aments. It is incomplete, not extending underneath the tendon of the
extensor muscle. Between the sides of the patella and the femur it consists of
fibres connected with the insertions of the vasti muscles and with the fascia lata,
and thus forms the structures which have been called lateral ixdellar ligaments.
Posteriorly it is thin, covering the condyles of the femur beneath the gastrocnemius
muscle, and it frequently presents an aperture beneath the inner head of that
muscle, through which the bursa under the semimeml^ranosus tendon is put into
communication with the joint-cavity.

The synovial membrane is the largest in the body. Traced downwards from
the femur on either side of the joint, it may be followed along the capsule to the

Fig. 213. — The superficial parts op the knee-joikt removed, and the external condyle of

THE KE3IUR SAWN OFF OBLIQUELi', TOGliTHER WITH HALF THE PATELLA, SO AS TO EXPOSE BOTH
THE CRUCIAL LIGAMENTS TOGETHER. (Alleil TboillSOn.) ^

In A, the parts are in the position of extension, in B, that of flexion, the figures being designed to
show the different states of tension of the crucial ligaments in these positions. 1, sawn surface of
femur ; 2, sawn surface of patella ; 3, iigamentuni patelko ; 4, anterior or external crucial ligament,
tense in A, and relaxed in B ; 5, posterior or internal crucial ligament, partly relaxed in A, tense in B ;
fi. internal, and 7, external semilunar fibro-cartilage ; 8, transverse ligament ; 9, articular surface of the
tibia, extending behind the external semilunar fii^ro-cartilage ; 10, on the head of the fibula, points to
the anterior superior tibio-peroneal ligament ; 11, upper part of the interosseous membrane.

upper surfaces of the semilunar filjrocartilages, round the free borders of those
structures to their inferior surfaces, and thence to the tibia. The crucial ligaments
are invested in front by a reflected portion of the membrane continued forwards
from the posterior wall of the joint. JJetween the tibia and patella the synovial
membrane lies upon a large pad or cushion of fat, on the surface of which it forms
two lateral fcjlds (alar lujaments) which pass to the side and upwards along the
lower border of the articular surface of the patella, while from the middle oi" the pad it
senrls backwards a A'arialjly developed process, the mucous ti/jamnit, thvoui^h the joint
to the front of the intercondylar fossa. Above the patella the synovial membrane
extends upwards for a short distance under the extensor tendon, and the pouch thus
formed communicates in most cases more or less freely with a bursa situated here
between the tendon and the anterior surface of the femur.

]1

THE ARTICULATIONS OF THE LOWER LIMB.

IMPRESSION
EXT. FIDRO-CA'

SEMILUNAR

PATELLAR

FACET

Idovements, &c. — In order to explain the nature of the movements, it is necessary to
state some considerations with regard to the relations of the several parts of the knee-joint
to each other. The knee-joint may be regarded as consisting of three articulations conjoined,
viz., that between the patella and femur, and two others, one between each condyle of the
femur and the tibia. In many mammals the synovial membranes of these three joints are
either completely distinct or communicate with each other by only small openings. In the
human subject the mucous ligament is an indication of this separation of the synovial
cavities of the inner and outer joints, and the crucial ligaments may be looked upon as the
external and internal lateral ligaments of those two joints respectively. On the cartilage-
covered articular surface of the femur also a corresponding subdivision into thiea parts is to

be recognised, the trochlear sur-
face for the patella being sepa-
rated from the convex tibial
surfaces by two shallow trans-
verse grooves which receive the
fibro-cartilages in the extended
position of the joint ; but along
the inner margin of the intercon-
dylar fossa there is marked off
from the rest of the internal
condyle a narrovf semilunar facet
which is in contact with the in-
nermost facet of the patella in
extreme flexion.

The movement of the patella
on the femur is one partly 'of
gliding, partly of coaptation. This
is illustrated by a careful exami-
nation of the articular surface of
the patella, which is not uniformly
curved from above downwards, as
it would be, were the movement one of gliding only, but exhibits on each side of the
vertical ridge three very slightly depressed surfaces, separated by two slight transverse
elevations, and along the inner margin a seventh area, upon which the transverse lines do not
encroach. "When the knee is extended, and the patella drawn upwards by the extensor
muscles, the two inferior facets of the patella are in contact with the upper margin of the

EXT. TIOIAL
GURl'.VJE

^r. COND'fLC
iriTERCOMDYLAR FOQSA
POST. CRUC. L13T.

Fig. 214. — Lower extrkmitt op the right femur,
BELOW. (Drawn by T. W. P. Lawrence.) |

Fig. 215. — Eight p.iTELLA, from behind. (Drawn by
T. W. P. Lawrence.) |

The articular surface is seen, divided by a ridge into a smaller
internal and a larger external part. On each of these three facets
may be recognized, of which the middle is the largest and the lower
the smallest, while along the inner margin there is a narrow seventh
facet.

trochlear surface ; in semiflexion the middle facets only are in
contact with the femru' ; in greater flexion, the superior parts
of the patella are in contact with the lower parts of the troch-
lear surface ; and in extreme flexion the patella, which has been gradually turned outwards
by the increasing prominence of the inner condyle, rests by its innermost facet against the
semilunar surface on the outer margin of the internal condyle, and by its upper and outer
facet on the fore part of the external condyle.

The articulation between each condyle and the opposed almost flat surface of the tibia,
while resembling, is not exactly a hinge-joint, and extension and flexion, the movements of
which it is capable, are produced by a combination of gliding, rolling, and rotation. If the
condyles of the femur be examined as they rest upon the tibia in the flexed position of the
joint, it will be seen that the inner condyle is longer than the outer, and that its anterior
portion inclines obliquely outwards to reach the patellar surface. In the movement of
extension the condyles move parallel to one another, both gliding and rolling until extension
is nearly completed, and then, the anterior part of the rolling surface of the external condyle
having already come into full contact with the tibia, the inner condyle continues to glide
backwards, bringing its oblique anterior part into contact with the tibia, so that the femur is
rotated inwards on the tibia. Similarly, the beginning of flexion is accompanied by a
rotation outwards of the femur, or inwards of the tibia. In complete extension the lateral
ligaments, the posterior ligament, and the anterior crucial ligament are tight, while the

THE TIBIO-FIBULAK ARTICULATIONS.

189

posterior crucial ligament is in part relarced ; in flexion, the posterior crucial ligament only is
tightened, the others being relaxed. Over-extension is prevented, not only by the tension of
the ligaments, but also by the anterior portions of the semilunar fibro-cartilages being pressed
into the grooves of the femoral artictilar surface, and the anterior margin of the intercondylar
fossa meeting the lower end of the anterior crucial ligament. In the last stage of the move-
ment of extension the inner part of the outer groove of the femur plays over^a special facet
of the tibia in front of the outer tubercle of the spine (fig. 210). In extension of the joint
no rotation of the leg is possible ; in the flexed condition a considerable amount is allowed.
Rotation out is checked by the internal lateral ligament, in by the anterior crucial ligament :
the whole range of movement, when the knee is bent to a right angle, is on an average about
40'' ; but it varies much in diflrerent individuals. The semilunar fibio-cartilages. being loosely
attached to the head of the tibia, move forwards in extension and backwards in flexion of
the joint : and farther, as the condyles rolling upon the tibia present successively to the
condylar surfaces of that bone portions having different curvatures, each cartilage, like a
moveable wedge, is contracted round the condyle during flexion of the joint and expanded
during extension. The mass of fat below the patella serves to fill up the space between the
ligamentum patella3 and the bones, and adapts itself to the varying form of this interval
during the movements of the joint, the alar ligaments projecting upwards into the angle
between the lower part of the patellar surface and the femur.

In the erect attitude, the knee-joint, like the hip. is maintained in the fully extended posi-
tion in great measure without muscular effort ; but there is some difference of opinion as to the
manner in which this is effected. According to the one view, which is supported by Humiihrv
and Langer, the line of gravity of the body falls in front of the axis of movement of the knee-
joint, and the tendency is thus to over-extension, which is resisted by nearly all the ligaments of
the articulation. On the other hand H. Meyer holds that the line of gravity falls slightly behind
the axis of movement, and that the stability of the knee depends mainly upon the association of
rotation with the beginning of flexion ; for. while the tibia is fixed by its connection with the
foot, the femm- is prevented from rotating outwards by the ilio-femoral ligament, which in
its tui-n is kept tense by the weight of the body acting on the hip-joint. Rotation between
the tibia and femur being thus impossible, flexion cannot take place, and the knee-joint is
fixed until by a slight bending at the hip-joint the ilio-femoral ligament is relaxed. Addi-
tional support is also given to the knee-joint by the tension of the ilio-tibial band of the
fascia lata (pp. 242 and 24'J). (H. Meyer, MiiUer's Archiv, 1853; Goodsir. ■•Anatomical
Memoirs." ii. 220. 2:]1 : Langer, Sitzungsber. d. Acad, der Wissensch. Wien, 1858. and ■• Lehrl).
d. Anat." ; Humphry. "A Treatise on the Human Skeleton ; " Henke, Zeitschr. flir lat. Med.,
viii, 1859 ; R. Bruce Young. On the grooves of the femur and locking of the knee-joint, in
'• 3Iemoii-s and Memoranda in Anatomy," 188'J.)

TIBrFIB.LlCT.

ANTELRIOR BAND

THE TIBIO-PIBUIiAR ARTICULATIONS.

The tibia and iibula form articulations at their upper and lower extremities,
and their shafts are united bj an interosseous membrane.

Upper tibio-fibular
articulation. — The supe-
rior extremities of the
bones present two flattened
oval articular surfaces, re-
tained in close contact by
thin anterior and posterior
superior tihio-fibutar I'nja-
menla, both of which pass
downwards and outwards
from the external tuberosity
of the tibia to the head of
the fibula. The synovial
cavity of this joint not un-
frequen tly com mu n i cates
posteriorly with that of the
kuee.

The interosseous membrane or ligament, which coimects the shafts of the
tibia and Iibula, pa.s.se.s between the exLcinal b(ji(Jer of the tibia and the interosseous

Fig.

&ROOVC OF PtRONEI

POST. BAND or EXT. LAT.LICT.
POST. INT. TIB.-FIB.LIGT.

216. — Inferior extrkmities ok the left tihi.v and
kibula, kkom bklow, showinu the uniting ligaments anu
the koumation of the sockkt of tiik ankle-juint.
( Drawn by T. W. P. Lawrence. ) g

190

THE ARTICULATIOKS OF THE LOWER LIMB.

ridge of the fibula (fig. 142), and is composed for the most part of parallel fibres run-
ning outwards and downwards, only a few fibres crossing in a different direction. It
presents superiorly an elongated opening for the transmission of the anterior tibial
vessels, and inferiorly a small interval is left between it and the lower articulation
for the passage of the anterior peroneal vessels.

Itower tibio -fibular articulation.- — The inferior extremities of the tibia and
fibula articulate by surfaces which for the most part are rough and bound together
by ligament, but at their lower part, for a distance of about a quarter of an inch, are
smooth and lined by synovial membrane. The tibial surface is concave, the fibular
is correspondingly convex. The strong short fibres which pass obliquely between
the opposed surfaces form the inferior interosseous ligament (fig. 219, 4). The
anterior ligament (fig. 222, 2) is a fiat band of fibres, extended obliquely over the
lower part of the bones, the direction of its fibres being downwards from the tibia to
the fibula. The posterior ligament is similarly disposed behind the articulation.
The transverse or inferior ligament is a short but thick band of yellowish fibres under
cover of the posterior ligament ; it runs horizontally from the hinder border of the
lower articular surface of the tibia to the contiguous part of the external malleolus,
and closes the angular interval between the bones.

The synovial cavity of this articulation is an extension of that of the ankle-joint.

EXTERNAL

MALLECLAR

FACET

THE ANKLE-JOINT

In this articulation, which is a hinge-joint, the inferior extremities of the tibia
and fibula are united so as to form a three-sided hollow, which embraces the astra-
galus : the socket is completed behind by the transverse ligament of the inferior
tibio-fibular articulation. The articular surface of the astragalus occupies the upper

surface of the body, and is continued
downwards on each side of the bone
ibr the corresponding malleolus. The •
inner margin of the superior surJace
is nearly straight; the outer margin
is convex, and inclined inwards pos-
teriorly, thus making the surface
narrower behind than iu front. Be-
tween the upper and the external sur-
faces posteriorly is a narrow trian-
gular facet which plays against
the transverse tibio-fibular ligament.
The capsule of the articulation is
divided into the following liga-
ments : —

The internal lateral or deltoid
ligament (fig. 221, 1) is a broad
layer of fibres, which radiate from
the internal malleolus to the tarsal
bones. The hinder part is thick
and short, and descends from the notch at the lower border of the malleolus to
the inner surface of the astragalus. The fore part, thinner and more expanded,
extends from the tip and .anterior border of the malleolus to the sustentaculum
tali of the os calcis, the internal calcaneo-navicular ligament, and the dorsal surface
of the navicular bone.

The external lateral ligament (fig. 222, 4, 5, 6) consists of three distinct
bands disposed in different directions. 1. The middle land descends from the

NT TUBERCLE

GROOVE OF FLEX. LONG. HAU..

Fig.

217. — The astragalus from above, showing the
articular surface and the attachments of the

LATERAL LIGAMENTS OF THE ANKLE-JOINT. (Drawn

by T. W. P. La-wrence.) |

THE A^'KLE- JOINT.

191

extremity of the fibula, to the external surface of the os calcis. 2. The anterior band
passes obliquely forwards and in\Yards from the fore part of the outer malleolus to
the body of the astragalus in front of its external malleolar surface ; it is the shortest
of the 'three. 3. The posterior band, the strongest of the three, passes almost

Fif. 218. — The lower tibio-fibulak articulation akd akkle-
joiN'T FROM BEHIND. (Alleu Tliomson. ) i

1, interosseous membrane ; 2. posterior ligament of the lower -"ibio-
fibular articulation ; 3. internal lateral ligament of the ankle-joint ; 4, pos-
terior, and 5, miiklle bands of the external lateral ligament of the ankle-
joint ; 6, external, and 7, posterior astragalo-calcaneal ligaments.

horizontally inwards from the pit on the inner side of the
malleolus to the external tubercle of the astragalus, and
the surface between the latter and the fibular articular
facet.

The anterior ligament is a thin and lax membrane
wliich passes from the anterior margin of the lower end of
the tibia to the upper aspect of the head of the astragalus.
Beneath it is a cushion of fat which rests in the hollow of
the neck of the astragalus.

The posterior ligament is fixed to the tibia and astra-
galus near their articular surfaces. Its fibres are weak, and
run chiefly inwards, radiating from the external malleolus
tipwards to th'j tibia and downwards to the astragalus.

The synovial cavity of the ankle-joint extends upwards for about a quarter of an
inch into the lower tibio-fibular articulation. On the outer side of the entrance to
this recess the synovial membrane forms a small fold containing fat, which occupies

Fig. 219. — Coronal section of the right ankle-joint near its

MIDDLE, AND OF THE POSTERIOR ASTRAGALO-CALCANEAL ARTICULA-
TION, viewed from BEFORE. ( A.llen Thomson. ) I

1. internal, 2, external malleolus ; 3, placed on the astragalus at the
angle between its superior and its external surfaces ; 4, inferior interos-
seous tibio-fibular ligament; 5, internal lateral. ligament of the ankle-
joint ; 6. sustentaculum tali ; 7, ealcaneo- fibular or middle part of the
external lateral ligament ; 8. inner part of the interosseous astragalo-cal-
caneal ligament ; t', tuberosity of the calcaneum.

tiic angular interval between the three bones, and is carried
upwards between the tibia and fibula when the external
malleolus is forced outwards in flexion of the ankle-joint. At
the front and back of the joint are larger synovial folds
projecting between the tibia and astragalus.

Movements, &c. — The movements of the ankle-joint are flexion, in which the toes are raised
towards the leg. and extension, in which the toes are depressed and the foot brouj^ht into the line
of the Ie;r. The whole range of movement does not exceed <M\ Although the horizontal surfaces
of both the tiVjia and astragalus arc broader in front than behiud. the malleoli are in contact
with the sides of the astragalus in all positions of the joint, a slight degree of lateral move-
ment of the external malleolus being permitted Ity the inferior til)io-fibular ligaments and the
ela.sticity of the shaft of the fibula. When the joint is bent the wide part of the astragalus is
pushed back into the socket, and the external malleolus is forced outwards ; whereas in
extension the external malleolus follows the curve of the outer surface of the astragalus,
being drawn inwards mainly by the posterior band of the external lateral ligament. In this
way a certain amount of spring is given to tlie articulation. In the mid-position of the joint.

192

THE ARTICULATIONS OF THE LOWER LIMB.

when the ligaments are least stretched, a limited degree of lateral motion is allowed under
the influence of external force, but it is probable that such movements do not occur naturally.
In the eiect attitude the line of gravity of the body falls slightly in front of the ankle-joint,
and a certain amount of muscular effort is required to maintain the position of the leg-bones ;
but stability is to some extent secured by the obliquity of the axis of the ankle-joinc, which
forms with its fellow, owing to the outward dnection of the foot, an angle, open backwards,
of about ISO''.

THE ARTICULATIONS OF THE FOOT.

Articulations of the asteag-alus with the calcaneijm and navicular
BONE. — The astragalus is connected with the calcaneum by two synovial articula-
tions, viz., by a posterior one peculiar to those two bones, and by an anterior one
common to them with the navicular bone. Two strong ligaments also unite the
navicular bone to the calcaneum.

Astragalo-calcaneal ligameiits. — The interosseous ligament (fig. 223), broad
and strong, passes downwards from the groove between the anterior and posterior

Fig. 220. — Ligaments of the foot, seen fkom below.
(Allen Thomson. ) \

1 and 2, portions of the internal lateral ligament of the ankle-
joint ; 3, long, and 3', short plantar ligaments ; 4, internal cal-
caneo-navicular ligament ; 5, three naviculo-cuneiform ligaments ;
6, is placed upon the external cuneiform bone, towards which is
seen coming from behind a cubo-cuneiform ligament ; 7, is placed
upon the internal cuneiform bone ; from 6 and 7, are seen passing
forwards the filantar cuneo-metatarsal ligaments ; x , part of the
first dorsal cuneo-metatarsal ligament : 8, plantar band from cuboid
to fifth metatarsal bone ; 9, fibres prolonged from the long plantar
ligament, forming the sheath of the jjeroueus longus tendon ; 10,

10, between these figures the plantar intermetatarsal ligaments ;

11, 11, transverse metatarsal ligament ; 12, intersesamoid liga-
ment ; 13, 13, between these figures are seen the five pairs
of internal and extercal lateral metatarso-phalangeal ligaments ;
14, 14, between these figures are seen the five pairs of in-
ternal and external lateral interplialangeal ligaments of the first
series ; those of the second series have no figure placed to mark
them ; 15, plantar ligament of the interphalangeal articulation of
the great toe.

articular surfaces of the astragalus to the similar
groove between the corresponding articular surfaces
of the calcaneum. The imsterior ligament (fig. 221 , 3),
thin and membranous, consists of short fibres which
radiate from the external tubercle of the astragalus to
the adjacent upper and inner part of the calcaneum. A
small internal ligament (fig. 221, 2) runs forwards from the internal tubercle of the
astragalus to the back of the sustentaculum tali, its upper fibres being continued
into the internal calcaneo-navicular ligament. There is also an inconstant external
ligament (fig. 218, 6), a shght fasciculus of fibres which descends from the outer
surface of the astragalus to the outer side of the calcaneum, parallel with the middle
division of the external lateral ligament of the ankle-joint. It may be farther ob-
served, that those portions of the lateral ligaments of the ankle-joint which pass
down over the astragalus to the os calcis assist in uniting these two bones.

Calcaneo-navicular ligaments. — The internal or inferior ligament is a broad
and thick band, in great part fibro-cartilaginous, which occupies the interval
between the sustentaculum tali and the navicular bone on the plantar aspect and
inner border of the foot. Its lower part springs from the anterior margin of the
sustentaculum tali, and is directed forwards and inwards to the inferior surface of
the navicular bone. Continuous with this, the fibres of the upper part of the liga-

THE ARTICULATIOXS OF THE FOOT.

193

ment run from the iimer extremity of the sustentaculum, in a radiating manner
forwards and upwards, to be fixed to the back of the tuberosity and the inner part
of the upper surface of the navicular bone, being joined by the anterior fibres of the
deltoid ligament of the ankle-joint, which descend from the internal malleolus. The
deep surface of the ligament is smooth and forms a part of the articular socket for
the head of the astragalus. On the superficial aspect of the upper portion of the
ligament is another smooth surface where the tendon of the tibialis posticus is in
contact with it. The ligament occasionally contains an ossification. The external
or superior calcanco-navicvlar lujameiit (fig. 222, 8 ; 223) forms the external boundary
of the socket just mentioned, and lies deeply at the anterior part of the fossa (sinus
tarsi) between the astragalus and os calcis. Its fibres, very short, are directed

Fie. 221. — LiGAlIKNTS OF THE FOOT, FROM THE INNER SIDE. (Allen TllOmSOn.) i

1, internal lateral ligament of the ankle ; x, below the sustentaculum tali, showing part of the
internal lateral ligament descending upon it ; 2, internal, and -3, posterior astragalo-calcaneal ligaments ;
4. part of the long and short plantar ligaments seen from the inside ; 5, astragalo-navicular ligament ;
6. superior part°of the internal calcaneo-navicular ligament, with the cartilaginous surface for liie
tibialis posticus tendon ; 7, 8, first, 9, second dorsal naviculo-cuneiform ligaments ; 10, intercuneiform,
or trasverse dorsal cuneiform, between the first and second cuneiform bones ; 11. first dorsal tarso-
metatarsal ligament ; 12, first plantar tarso-metatarsal ; 13, internal lateral metatarso-phalungeal ; Uic
internal sesamoid bone is seen below ; 14, internal lateral interphalaugeal ligament of the first toe.

from behind forwards and inwards between the contiguous extremities of the bones.
They arc attached posteriorly to the foremost part of the upper surface of the os
calcis between the articular surfaces for the astragalus and cuboid, and anteriorly to
the outer side of the navicular bone.

The astragalo-navicular ligament, a membranous band situated on tlie
dorsum of the foot, consists of two portions which converge as they pass forwards
from the head of the astragalus to the upper surface of the navicular bone, and com-
pletes the fibrous capsule of the astragalo-calcaneo-navicular joint, formed in tlie
rest of its extent by the internal and external calcaneo-navicular ligaments.

The two si/novial raviiies of these articulations are separated by the interosseous
ligament rfiir. 22;>): the posterior belongs to the astragalo-calcaneal joint, the ante-
rior to the astragalo-calcaneo-navicular articulation.

Calcaxeo-ciiijoii) auticulatiox.— The calcaneum is united to the cuboid bone
by a synovial joint with surrounding ligaments.

194

THE ARTICULATIONS OF THE LOWER LIMB.

The inferior ligament consists of two distinct layers, of which one is superficial,
the other deep-seated. The superficial part, called the long ijlantar ligament
(fig. 220, 3), is the longest of the tarsal ligaments. Its fibres, attached behind to
the inferior surface of the calcaneum as far as the anterior tubercle, pass forwards,
and are attached in greater part to the ridge on the under surface of the cuboid
bona ; but some of them are continued onwards to the bases of the third, fourth
and fifth metatarsal bones, covering the tendon of the peroneus longus muscle. The
deep-seated part, or short lolantar ligament (fig. 220, 3'), lies close to the bones, being
separated from the superficial part by some areolar tissue. Its breadth is consider-
able, its length scarcely an inch. One extremity is attached to the front of the ante-

Si) 21 22

Fig. 222. — Ligaments of the foot, from the outer and dorsal aspect. (Allen Thomson.) §

1, lower part of the interosseous membrane ; 2, anterior inferior tibio-perones,! ligament ; 3,
posterior inferior tibio-peroneal ligament ; 4, middle, 5, anterior, and 6, posterior parts of the external
lateral ligament of the ankle-joint ; 7, is placed above the interosseous astragalo-calcaneal ligament ; 8,
external calcaneo-navicular ; 9, dorsal calcaneo-cuboid ; 10, part of the long plantar or inferior calcaneo-
cuboid ; 11, asti-agalo-navicular ; 12 and 13, second and third naviculo-cuneiforu], and between them
one of the intercuneiform ligaments ; 14, superior naviculo-cuboid ; 15, placed on the external
cuneiform bone, points to the cuneo metatarsal ligaments from that bone to the second, third, and fourth
metatarsal bones; 16, cuneo-metatarsal ligament,- from the first cuneiform to the second metatarsal
bone ; between 15 and 16, are seen the cuneo-metatarsal ligaments which converge from the three
cuneiform bones on the second metatarsal; 17, 18, cubo-metatarsal ligaments; 19 and x x, dorsal
intermetatiirsal ligaments ; 20, lateral raetatarso-phalangeal ; 21, 22, lateral interphalangeal.

rior tubercle of the calcaneum, the other, somewhat expanded, to the depressed
surface of the cuboid bone behind the ridge.

The dorsal or superior ligament is a flat band, connecting the upper surfaces of
the calcaneum and the cuboid bone.

The internal or interosseous ligament is placed deeply in the hollow between the
astragalus and os calcis, and is closely connected with the external calcaneo-
navicular ligament.

This joint has a separate sgnovial cavitg.

The name transverse tarsal articulation is given to the interrupted line of
articulation crossing the foot between the astragalus and os calcis behind, the
navicular and cuboid in fi'ont.

Articulations of the navicular, cuboid, and cuneiform bones, ONii
WITH another. — Uaviculo-CTiboid articulation. — The navicular and cuboid
bones are connected by a dorsal ligament, composed of short fibres, extending
obliquely between the two bones; 2, plantar ligament, consisting of transverse fibres;

THE ARTICULATIONS OF THE FOOT.

195

and a strong interosseous ligament, which intervenes between their contiguous sur-
faces. When the bones touch, which is not always the case, they present two small
articulating surfaces, which are covered with cartilage and have between them an
offset of the adjacent naviculo-cuneiform synovial cavity.

Naviculo-cuneiform articulation.— The navicular articulates with the three
cuneiform bones by the smooth facets on its anterior surface, forming one continuous
joint. They are united by dorsal ligaments, passing from the upper surface of the
navicular to the first, second and third cuneiform bones, and by j^l^niar ligaments,
which are similarly disposed on the under surface of the bones, but these are con-
tinuous with, or offsets from, the tendon of the tibialis posticus muscle.

Cubo- cuneiform articulation. — The cuboid and the external cuneiform bones
are connected by a dorsal ligament, which is a thin fasciculus of transverse fibres •

INTEROSS. ASTRAG. CAUC. LIGT.

EXT CALC NAV LIGT

Fig. 223. — Section of the foot, showing the synovial cavities of the tarsal and tarso-
metatarsal ARTICULATIONS. (G. D. T.)

The section is carried nearly vertically through the astragalus, obliquely upwards and inwards across
the other bones. 1, posterior astragalo-calcaneal articulation ; 2, astragalo-calcaneo-navicular articula-
tion ; 3, calcaneo-cuboid articulation ; 4, naviculo-cuneiform articulation, the common synovial cavity
extending forwards to the articulations between the cuneiform and the second and third metatarsal
bones ; 5, cubo-cuneiforra articulation (this is frequently continuous with the foregoing) ; 6, cubo-
metatarsal articulation (this sometimes communicates with the adjoining cuneo -metatarsal joint) ; 7,
internal cuneo-metatarsal articulation.

ajylantar ligament, the fibres of which are also transverse and rather indistinct ; and
a bundle of interosseous fibres. Between the two bones an articulation is formed
by cartilaginous surfaces ; it is provided sometimes with a separate synovial
sac, at others with an offset from that which belongs to the naviculo-cuneiform
articulation.

The three cuneiform bones are connected by transverse dorsal ligaments and
strong interosseous fibres, the latter being their most efficient uniting structures.
The synovial cavity of the naviculo-cuneiform articulation sends forwards two
processes between these bones.

Articulations of the tarruh with thk metatarsus. — The four anterior
bones of the tarsus, viz., the three cuneiform and the cuboid, articulate with the
metatarsal bones ; and as the first and third cuneiform bones project beyond the
middle one, and the third cuneiform l>eyond the culjoid bone, the anterior surface
of tiie tarsus is verv irregular. The first metatarsal bone articulates with the

196 THE ARTICULATIONS OF THE LOWER LIMB.

internal cuneiform ; the second is wedged in between the first and third cuneiform,
and rests against the second ; the third metatarsal bone articulates with the
extremity of the external cuneiform ; and the last two with the cuboid bone, the
fourth having also usually an articulation with the external cuneiform. The articu-
lations are synovial joints, and the bones are held in contact by dorsal, plantar, and
interosseous hgaments.

The dorsal tar so -metatarsal ligaments (fig. 222) are flat thin bands of parallel
fibres, which pass from behind forwards, connecting the contiguous extremities of
the bones before mentioned. Thus the first metatarsal bone receives a broad thin
band from the corresponding cuneiform bone ; the second receives three, which
converge to its upper surface, one passing from each cuneiform bone ; the third has
one from the external cuneiform bone ; and, finally, the last two are bound by a
fasciculus to each from the cuboid bone, and by fibres from the external cuneiform
to the fourth metatarsal bone. The flantar ligaments are less regular ; the bands
of the first and second metatarsal bones are more strongly marked than the corre-
sponding ligaments on the dorsal surface ; and those of the fourth and fifth, which
are merely a few scattered fibres passing from the cuboid, receive support from the
prolongation of the long plantar ligament, forming the sheath of the peroneus
longus tendon. Ligamentous bands stretch in an oblique direction from the
internal cuneiform to the second and third metatarsal bones ; and others, less
developed, run nearly transversely from the external cuneiform to the fifth
metatarsal.

The interosseous ligaments run forwards between the bones, and from their
strength and deep position oppose great resistance to the knife in separating the
metatarsus from the tarsus, a. The internal and largest of these extends from the
outer side of the first cuneiform bone to the neighbouring side of the second
metatarsal, close to the articular surface. h. The middle, which is the
smallest, and is less constant than the others, passes from the external cunei-
form to the outer side of the second metatarsal bone. c. The external connects
the outer side of the external cuneiform to the same side of the third metatarsal
bone.

Synovial cavities. — There are three synovial cavities in this irregular series of
articulations, a. One is between the internal cuneiform and the first metatarsal
bone ; the joint formed between these two bones is altogether separate and out of
the range of the rest. &. A second synovial cavity is between the cuboid and the
fourth and fifth metatarsal bones, and sends a small process forwards between the
latter bones, c. The third or middle one is placed between the middle and external
cuneiform and the second and third metatarsal bones, and is prolonged between the
two last-named bones, as well as between the third and fourth metatarsal bones.
This cavity generally communicates between the internal and middle cuneiform
bones with that of the naviculo-cuneiform articulation.

Inteemetatarsal articulations. — The metatarsal bones are bound together,
at their tarsal and digital ends ; very firmly in the former, and loosely in the latter
situation.

The tarsal ends of the four outer bones articulate with each other, having lateral
cartilaginous surfaces, between which processes are sent forwards from the outer two
synovial cavities of the tarso-metatarsal articulations, and they are connected by
dorsal, plantar, and interosseous ligaments. The dorsal and plantar ligaments are
short transverse bands stretching across the four metatarsal bones from one to
another. The interosseous ligaments, lying deeply between the bones, connect the
rough parts of their lateral surfaces ; they are of considerable strength and firmness.
Between the first and second metatarsal bones there is often a bursa, corresponding
to a small articular facet on the base of the former bone, while on the latter there is

THE ARTICULATIONS OF THE FOOT. 197

only an indistinct smooth surface covered by synovial membrane (see figs. 152 and
154) : this bursa may communicate with the first cuneo-metatarsal joint.

Transverse metatarsal ligament. — The digital extremities or heads of the
metatarsal bones are loosely connected by a transverse band, which is identical in its
arrangement with the corresponding structure in the hand, with this exception, that
it is attached to the great toe, whereas in the hand the transverse metacarpal
ligament does not reach the thumb.

Met AT ARSO -PHALANGEAL AXD INTERPHALANGEAL ARTICT'LATIOXS. — The heads

of the metatarsal bones are connected with the small concave articular surfaces of
the first phalanges by two lateral ligaments, an inferior ligament, which is developed
into a \\i\Qkfil)rous or sesamoid plate, and a synovial membrane, — all being closely
similar to the corresponding parts of the hand. In the first metatarso-phalangeal
articulation the sesamoid plate is divided into two parts, which are fully ossified,
forming the sesamoid bones. These are held together by strong transverse liga-
mentous fibres, and being provided with cartilaginous surfaces, move upon the
corresponding grooved cartilaginous surfaces of the head of the first metatarsal bone.

Fig. 224. — Sagittal section of the ankle-joint and articulations of the right foot, a little
TO the inside of the middle of the great toe. (Allen Thomson.) -J

1, synovial cavity of the ankle-joint ; 2, posterior astragalo-ealcaneal articulation ; 3, 3', astragalo-
calcaneo-navicular articulation : the interosseous ligament is seen sejiarating 2 from 3' ; 4, inferior
calcaneo-navicular ligament ; 5, jjart of the long plantar ligament ; 6, naviculo-cuneiform articulation ;
7, first cuneo-metatar.sal articulation ; 8, first metatarso-phalangeal articulation ; 9, section of the inner
sesamoid bone ; 10, interphalangeal articulation ; 11, placed on the calcaneum, indicates the bursa
between the upper part of the tubeiosity of that bone and the tendo Achillis.

The articulations of the phalanges with one another are also constructed on the
same plan as those of the superior extremity. In each the bones are held in contact
by two lateral ligaments and an iiiferior ligament or fihrous plate ; and each of the
cavities is lined by a synovial membrane.

Mechanism and movements. — In the mechanism of the foot a longitudinal and a
transverse arch are to be recognized, both of them capable of being flattened somewhat by
pressure from above, thus securing elasticity. The longitudinal arch, as analyzed by v.
Meyer, is formed primarily Vjy the calcaneum, astragalus, cuboid, navicular, external cunei-
form and third metatarsal bones, the external cuneiform being wedged in between the
navicular and cuboid, and the third metatarsal being firmly united at its base by strong
ligaments, so that very little movement is allowed. To the slender anterior i)illar of the
arch lateral supports are added, the fourth and fifth metatarsal bones on the outer side, the
second and first metatarsal bones on the inner side, which are capable of greater movement,
can be a/]justed to the form of the supporting surface, and are brought into play according as
the weight is thrown on the one or the other side of the foot. The first metatarsal bone and
the great toe have their chief use in progression. In making a step, as the heel of the

198 THE AETICULATIONS OF THE LOWER LIMB.

supporting foot leaves the ground, the outer side of the foot is raised, the weight is thrown
onto the second, and then the first metatarsal bone, and the propulsion is completed by the
flexion of the phalanges of the great toe. The longitudinal arch is supported by the strong
plantar ligaments, especially the calcaneo-navicular and calcaneo-cuboid, assisted by the
plantar fascia and the muscles of the sole. The transverse arching of the foot is most
marked in the line of the tarso-metatarsal articulations, and is maintained by the plantar
and interosseous ligaments. The weight of the body in standing, especially when the
heel is raised from the ground, tends to spread out the metatarsal bones at their distal
extremities, and to flatten the transverse arch, which recovers its position when the pressure
is removed.

The chief movements taking place between the tarsal bones are those of inverswn and
eversion of the foot, which have their seat mainly in the astragalo-calcanean and transverse
tarsal articulations. In inversion the fore part of the foot is depressed and carried inwards,
the longitudinal arch is increased, and the outer part of the foot descends more than the
inner, so that the sole is turned to sonae extent inwards. In eversion these actions are
reversed, and the foot resumes its normal position. The movement between the astragalus
and calcaneum is a rotation about an axis which is directed obliquely from the upper and
inner part of the neck of the astragalus, backwards, downwards, and outwards, to the lower
and outer part of the tuberosity of the os calcis, so that in inversion the posterior articular
surface of the os calcis glides forwards and downwards beneath the astragalus, the susten-
taculum tali moves backwards and upwards, and the anterior extremity of the bone is carried
slightly inwards. The navicular and cuboid bones are moved at the same time downwards
and inwards over the fore part of the astragalus and calcanei^m respectively. The move-
ment is assisted by a slight amount of gliding between the anterior tarsal bones, and between
these and the metatarsal bones. Inversion of the foot is commonly associated with extension,
and eversion with flexion of the ankle-joint. The metatarsal bones are capable of only a
limited amount of movement, by which they are carried downwards and brought together
(opposition), or raised and separated. This movement is necessarily freest in the first and
fifth metatarsal bones, while the third moves hardly at all. It is, however, to be remarked
that the movement of the first and second metatarsal bones does not wholly take place
between them and the corresponding cuneiform bones, but to a considerable extent also in the
naviculo-cuneiform articulations. The movements of the metatarso-phalangeal and inter-
phalangeal articulations are similar to those of the corresponding joints of the fingers, but
are more restricted in their extent. In the condition of rest the metatarso-phalangeal
articulations of the smaller toes are slightly over-extended, while the interphalangeal joints
are somewhat flexed, (Gr. H. v. Meyer, " Statik und Mechanik des menschlichen Fusses,"
1886.)

INDEX AND GLOSSARY TO VOL. IL, PT. L^

Abduction, 151

Accessory ligaments of atlas, 155

occipito-atlaiital ligament, 157

palatine canals, 54

process of lumbar vertebrae, 11, 23
Acetabulum (vessel for holding vinegar), no,

115. 136
Acrocephaly {&Kpov, summit ; xec^oArj, head), 86
Acromial angle, 90
Acromio-clavicular articulation, 165
Acromion (aKpou ; Sifxas, shoulder), 90, 106
Acromio-scapular notch, 90
Adduction, 151
Addiictor tubercle, 121
Agger (mound) nasi, 52
Air-sinuses in bones of head, 7 1
Alse (ala, wing) of sacrum, 15

of vomer, 55
Alar ligaments, of knee, 1S7
odontoid, 156

processes of ethmoid, 48
Alisphenoid, 75, 80
Alveolar index, 85

point, 83

process, 50, 52, 58
Alveoli (alveolus, small hollow vessel) of lower
jaw, 58

of upper jaw, 52
Amphiarthrosis {a.fji<pi, on both sides, inter-
mediate ; &pdpoi/, joint), 148
Anapophysis (am, upon ; apophijsiH), 11, 23
Anatomy (ara, apart ; rffivu, cut), descriptive, i

systematic and topographical, i
Angle, acromial, 90

of lower jaw, 59, 61

of pubis, 113

of rib, 26

subcostal, 29

of torsion, of femur, 123
of humerus, 94
of tibia, 127
Angular movement, 151

pjrocesses of frontal bone, 37
Ankle-joint, ligaments of, 190

movements of, 191
Annular (annulun, ring) ligaments. See Liga-

MKXT.

Antibrachial index, 99

Antibrachium (avri, op[)Ositc ; hrachium), 86

Antrum (cavern), 4

of Highmore, 50, 53, 72, 77

mastoid, 75
Aperture, anterior nasal, 62
Apophysis Ian6, from ; tpiiw, grow), 4
Appendicular jiortions of body, 4, 140
skcdeton, 4

Aqueduct of cochlea, 42

of Fallopius, 42

of vestibule, 42
Arch, alveolar, 67

of atlas, 7

orbital, 37

scapulo-clavicular, 164

subpubic, 116

of vertebra, 5

zygomatic, 64
Arches, inferior, of skull, 81

superior, of skull, 81

of vertebrae, 5, 7, 21
Area cribrosa media, 43

superior, 43
Arm, bones of, 86, 106, 140
Arnold's nerve, foramen for, 43
Arthrodia {apOpcvSia, a joint with shallow socket,

Galen), 149
Arthrology {&p6pov, joint ; \6yos), 147
Articular eminence of temporal bone, 41, 75

processes of vertebrae, 5, 6, 7, 8, 9, 11
homology of, 21
joints of, 153

surfaces, 150
Articulations {articulus, joint ; diminutive of
artvs, limb), 147

acromio-clavicular, 165

of ankle, 190

of astragalus, 192

of atlas and axis, 155

calcaneo-cuboid, 193

ofcalcaneum, 192

carpal, 173

carpo-metacarpal, 175

chondro-sternal, 159

classification of, 147

of coccyx, 178

coraco-clavicular, 165

of costal cartilages, 29, 160

costo-central, 158

costo-clavicular, 165

costo transverse, 159

cubo-cuneifonn, 195

development of, 150

of elbow, 170

of foot, 192

of forearn), 169

of hand, 173

of hip, 181

intercarpal, 173

interchondral 29, 160

intermetacarfial, 175

intermetatarsal, 196

inter[)halangeal, of hand, 176
of foot, 197

' Names printed in /to^tcs denote varieties.

11

IXDEX AND GLOSSARY TO VOLUME IL, PART I.

Articulations — continued.
of knee, 183
of lower limb, 181
lumbo-sacral, 177
metacarpo-phalangeal, 176
metatarso-phalangeal, 197
modes of, 147
movements of, 151
of navicular bone, 192, 193, I94> ^95
naviculo-cuboid, 194
navicnlo-cnneiform, 195
of occipital bone, 155
of pelvis, 177
of pisiform bone, 1 74
pubic, 180
radio-carpal, 172
radio-ulnar, 169
of ribs, 158
sacro-coccygeal, 178
sacro-iliac, 178
sacro-vertebral, 177
sca]mlo-clavicular, 164
of shoulder, 1 66
sternal, 161
sterno-clavicular, 164
tarsal, 192
tarso-nietatarsal, 195
temporo-maxillary, 162
of thorax, 158
tibio-fibular, 189
transverse carpal, 173

tarsal, 194
of trunk and head, 151
of upper limb, 164
of vertebral column, 151
of wrist, 172
Asterion (acrr^p, star), 84
Asternal (a, neg. ; aripvov, breast) ribs, 25
Astragalo-calcaneal ligaments, 192
Astragalo-navicular ligament, 193
Astrao'alus {o.(npa.-ya.Kos, ankle-bone, or die, the
astragali of sheep having been used as dice by
the ancients), 130
articulations of, 192
homology of, 144
ossification of, 1 38
Atlanto-axial ligaments, 157, 158
Atlas, 7

homology of, 21
ligaments of, 155
movements of, 158
ossification of, 19
varieties of, 8
Auditory meatus, external, 41, 64, 75
internal, 42, 43, 71
process, external, 41
Auricular point, 84

surface of ilium. 112, 17S
surface of sacrum, 14, 178
Auriculo-bregmatic line, 84
Axial skeleton, 4

relation of limbs to, 140
Axis (vertebra), 8
homology of, 21
ligaments of, 155
ossification of, 20
of pelvis, 117

Ball and socket joikt,
Basihyal, 80

149

Basilar groove, 34

process of occipital bone, 31, 34, 67
Basoccipital, 73, 79
Basion {^dcris, base), 84
Basisphenoid, 75, 80
Beak of olecranon, 95
Berlin, bones of, 44
Bicipital groove, 93

tuberosity, 98
Bones, Descriptive Anatomy of, 3
astragalus, 130, 138, 144
atlas, 7, 19, 21
axis, 8, 20, 21
of Berlin, 44

calcaneum, or os calcis, 129, 138, 144
carpal, 100, 108, 143
clavicle, 86, 106, 140
coccyx, 5, 16, 21
cuboid, 132, 138, 143
cuneiform, of carpus, loi

of tarsus, 131, 138, 144
ejjiptcric, 62, 84
ethmoid, 47, 76, 80
femur, 118, 137, 142
fibula, 127, 138, 142
frontal, 36, 74, 80
of head, 31

]iomologies of, 79
ossification of, 73
hip, no. 136, 140
humerus, 91, 107, 142
hyoid, 61, 78, 80
ilium, no, 136, 140
innominate, no, 136, 140
interparietal, 34, 73, y9, 80, 84
ischium, 113, 136, 140
lachrymal, 57, 77, 80
of limbs, liomological comparison of, 140

morphology of, 140
of lower limb, 1 10

ossification of, 136
lunar, loi, 108, 143, 144
maguum, 102, 108, 144
malar, 55, 78, 80
maxillary, inferior, 58, 78, 80

superior, 50, 77, 80
metacarpal, 103, 109
metatarsal. 133, 138
nasal, 56, 77, 80

navicular, of tarsus, 131, 138, 144
number of, 4
occipital, 31, 73, 79
palate, 53, 77, 80
parietal, 35, 74, 80
patella, 124, 138, 144
phalangeal, of hand, 105, 109

of foot, 135, 139
pisiform, loi, 108, 144
pubic, 113, 136, 140
pyramidal, loi, 108, 143
radius, 97, 107, 143
ribs, 25, 31
sacrum, 5, 13, 20
scaphoid, of carpus, loi, 108, 143

of tarsus, 131, 138, 144
scapula, 87, 106, 140
semilunar, loi, 108, 143, 144
sesanroid, in hand, 105, 176

in foot, 135, 197
sphenoid, 43, 75, 80
spongy. Sec turbinate.

INDEX AND GLOSSARY TO VOLUiME II., PART I.

Ill

Boi^ES— continued.
stern ura, 23, 30

sKjjyastci-ncd, 25

tarsal, 129, 138. 143, 144

teniiioral, 39, 74, 80

tibia, 124, 138, 142, 144

trapezium, 102, 108, 144

trapezoid, 102. 108, 144

tiicjuetral, 62

turliinate, inferior, 58, 78, 80
middle, 49, 72, 80
siiheiioidal, 44, 76, So
superior, 49, 72, 80

ulna, 95, loS, 142

iinciforiii, 103, loS, 143

of upper limb, 86

ossification of, 106

vertebra?. See Veutkbr^.

vomer, 55, 77, 80

Wormian, 62, 74
Brachium {fipaxtuv, arm), 86
Bracbvceplialic (^pax''>s, short ; K!(pa\r], head)

skulls, 84
Branchial {$pdyxia, gills) arches, 81
15reast-boiie, 23

Brerrma {&piyiua, upper part of head), 83
Brim of true pelvis, 115

CAi.t'ANEO-cuBOiD articulatiuu, 193

Caleaneo-navicular ligaments, 192

Calcaneum (belonging to the heel, from cnb:,

heel). See Os Calcis.
Calcar (spur) femorale, 123
Calvaria (skull cap), 68
Canal, of bone, 4

carotid, 42, 68, 70

dental, anterior, 51
inferior, 59
middle. 51
posterioi', 50, 65

Eustachian, 42

incisor, 52

infraorbital, 51, 63, 77

malar, 56, 63, 64

neural, 6

orbital, internal, 38, 49, 64, 69

palatine, accessory. 54, 67
anterior, 52
posterior, 51, 54, 67

])alato-ma.\illary, 51, 54, 67

pterygoid, 47

pterygo-palatine, 47, 54, 65

sacral, 15

spinal, 6

temporal, of malar bone, 56, 64

Vidian, 47, 65, 70
CannJiculas innombuUiis, 47
Canine fossa, 50, 63
Ca])itellum or i^ipituluni (dim. oi eaput, head), 4

of humerus, 94

of lib, 26
Cajiitnlar yjroce.sses of dorsal vertebra;, 23
Capsular ligament of hip, 182
of knee, 1S7
ofshouldei-, 166
Caput (head) of bone, 4
Carotico-clinoid fe/ro, nu, n , 47
Carotid canal, 42, 68, 70

foramen, 42
Carj)al articulations, 173

Carpalia, 143

Carpo-metacarpal articulations, 175

Carpus {KapTr6s, wrist), bones of, 100

homologies of, 143

ossification of, 108

compared with tarsus, 143

ligaments of, 173
Cartilage (eartilago) of ribs, 28

connections of, 160

varieties of, 29

See Fibko-Cakti lage.
Cavity, cotyloid, 4, 115

cranial, 68

glenoid, 4, 90

nasal, 71

sigmoid, of radius, 99
of ulna, 95
Cells, ethmoidal, 48, 72
Centrale, 103, 143
Centrum of vertelDrse, 5, 21
Cephalic {K(^a}\ri, head) index, 84
Ceratohyals (<f€paj, horn ; hyoicl), 80
Cervical vertebra^ 6
Cervix (neck) of bone, 4
Check ligaments, 156
Chest. See Thokax.
Child, characters of .skeleton in, 145
Chondro-sternal articulations, 159
Circumduction, 151

Clavicle (eluvicula, dim. of eJavia, key ; pro-
bably transl. from KKfis, key or bolt,
collar-bone), 86

homology of, 140

ligaments of, 164

ossification of, 106
Clavicular notches, 25
Clinoid («AiVr;, bed ; elSos, shape) processes, 44,

45 > 47
Coaptation (con, together; aptu, fit), 151
Coccyx (k6kkv^, cuckoo), 5, 16

articulations of, 178
, ossification of, 21
Cochlea, aqueduct of, 42
Cochleariforni [coehlcare, .spoon ; forma, shape,

process, 42
Colhu'-bone, 86

Condylar foramina, anterior, 33, 68, 71
posterior, 33, 71

fossa, posterior, 33

]iortions of occipital bone, 31, 33

surfaces of tibia. 124
Condylarthrosis {k6v^uKos ; apdpov), 149
Condyle (kuvSv\os, knuckle), 4
Condyles of fenuu-, 121

(jf humerus, 94

of lower jaw, 59, 64

of occipital bone, 31, 33, 68
Condyloid joint, 149
Congruent articular surfaces, 150
Conjugal ligament of ribs. 159
Conoid {koivos, cone ; eI5os, sliajte) ligament,
165

tubercle, 87
Continuous articulation, 147
Coraco-acromial ligament, 166
Coraco-clavicular articidalion, 1 65
Coraco-clavicular ligament, 165
CorOjCO-ijUnold liiidinent, 167
Coraco-humeral ligament, 167
(Joraco-.scapular ligament, 166
notch, 90

IV

INDEX AND GLOSSAEY TO VOLUME II., PAET 1".

Coracoid {Kopa^, raven : dSos, shape) process of

scapula, 90, 106, 140
Coruicula {corniciilum, dim. of cornu, horn) of

hyoid bone, 61
Cornua of coccyx, 16
of hyoid bone, 61
sacral, 14
sphenoidalia, 44
Coronal {corona, crown) sutnre, 61
Coronoid {Kopdvr], anything hooked, e.g., the tip
of a bow) fossa of humerus, 94
process of lower jav/, 60, 64, 78
of ulna, 95
Costse or ribs, 25, 30
Costal cartilages, 25, 28

articulation of, 29, 160
Costo-central articulation, 158
Costo-clavicular articulation, 165
Costo-clavicular ligament, 164
Costo-transverse articulation, 159
Costo-xiphoid ligament, 160
Cotyloid (Korv\7], cup ; elSo?, shape) cavitj', 4
of hip-bone, 115
ligament, 181
notch, 115
Cranial capacity, 82, 83

cavity, 68
Cranio-facial axis, bones forming, 81
Craniometry {Kpaviof ; /j.erpoi', measure), 82
Cranium (Kpaviof, skull), 31. See Skull.
Crest of bone, 4
ethmoidal, 54
frontal, 38
of ilium, 110
incisor, 52
infratemporal, 46
lachrymal, 57
nasal, 52, 53
obturator, 113

occipital, external and internal, 32, 33
pubic, 113
sphenoidal, 44
supramastoid, 40, 64
temporal, 37
of tibia, 126

turbinate, inferior, 51, 53
superior, 54
Cribriform (cribrum, sieve ; forma, shape) plate
of ethmoid bone, 48, 49, 69, 82
of temporal bone, 42, 43
Crista falciformis, 43

galli (cock's comb), 48, 69
Crucial (c7-ux, cross) ligaments, 184
Cruciform ligament, 155
Cube- cuneiform articulation, 195
Cuboid (kv0os, cube ; elSos, shape) bone, 132
homology of, 143, 144
ligaments of, 193, 194, 195
ossification of, 138
Cuneiform {cuneus, wedge ; forma, shape) bones
of foot, 131
homology of, 144
ligaments of, 195
ossification of, 138
of hand, loi
Curved lines of occipital bone, 32
Cylindrical bones, 4

Deltoid (AeAra, the letter A, or delta ; eI5os,
shape) eminence, 93
ligament, 190

Deltoid tubercle, 87
Dental canal, anterior, 51

of lower jaw, 58, 59
middle, 51
posterior, 50, 65

foramen, 59
Dentated suture, 147
Dentary nucleus of lower jaw, 78
Dermal (Se'p/ua, skin) skeleton, 3
Development of articulations, 150
Diaphysis {Sid, between ; ^vw, grow), 3
Diapophysis {Std, apart ; a2wp7v!sis), 23
Diarthrosis {StdpOpuKris, moveable articulation ;

oipdpov, joint), 148
Digastric {Sis, twice ; yaaTrip, belly) fossa, 41, 68
Digital fossa of femur, 119

phalanges, 105, 135
Digitus posiminimus, 144
Diploe (StTfAoos, double), 68
Disc, interpubic, 180

intervertebral, 151
Discontinuous articulation, 148
Dolichocephalic {SoXix'^s, long ; KecjyaXT], head)

skulls, 84
Dolichopellic (5oAix<^^ ; ireAAa, bowl) pelvis, 118
Dorsal vertebrae, 9

Dorsum sellse (back of saddle), 44, 70
Duct, nasal, 51, 57, 72

Elbow- JOINT, 170

Eminences of bones, 4

Eminence, articular, of temporal bone, 41, 75

deltoid, 93

frontal, 37, 82

ilio-pectineal, 112

olivary, 43, 70

parietal, 35, 82
Enarthrosis (eV, in ; <zp9pov, joint), 149
Eudoskeleton {evSov, within ; skeleton), 3
Ensiform {cnsis, sword ; forma, shape) process,

23, 25
Epicondyle {iiri, on ; condyle), 94
Epihyal (eiri ; hyoid hone) bones, 80, 163
Epiotic (<=7ri ; ovs, gen. wt6s, ear) centre, 75
Epiphysis {eivi ; cpvai, grow), 4
E'pipteric {iiri ; pterion) hone, 62, 84
Epitrochlea (eiri ; trochlea), 94
Erect attitude, adaptation of skeleton to, 145

maintenance of, 183, 189, 192
Ethmoid {r]9fji.6s, sieve ; dSos, shape) bone, 47, So

ossification of, 76
Ethmoidal cells or sinuses, 48, 72, 77

crest, 54

notch, 36

process of inferior turbinate bone, 58

spine, 44
Ethmoturbinals, 49, 80
Eustachian canal, 42

tube, groove for, 46, 68
Eversion of foot, 198

of ribs, 161
Exoccipitals, 73, 79
Exoskeleton (I'loi, outside ; skeleton), 3
Extension, 151

Face, bones of, 31

Falciform {falx, sickle or scythe ; forma, shape)
crest, 43
process of great sacro-sciatic ligament, 179

INDEX AND GLOSSARY TO VOLUME 11. , PART I.

Fallopius, aqueduct of, 42

hiatus of, 42, 70
False ribs. 25

vertebrae, 5
Femoro-tibial iudex, 127
Femur, iiS

compared with humerus, 142, 144

ossitication of, 137
Fibro-cartilage, interarticular, aeromio-clavicu-
hir. 165
of knee, 185, 186
of lower jaw, 163
radio-ulnar or trianguhir, 169
scapulo-clavicular, 165
sterno-clavicuhir, 164
Fibro-plate, 150
Fibula (brace, clasp), 127, 142

ossitication of, 138
Fibulare, 143
Fingers, bones of, 105

movements of, 176
Fisnira sterni, 25
Fissure of bone, 4

of Glaser, 41, 42, 43

incisor, 77

petro-basilar, 68

petro-sphenoidal, 68

petro-squamous, 42

pterygo-maxillarv, 65

sphenoidal, 47, 63, 70

.s[iheno-maxillaiy, 63, 65
Flat bones, 4

Flexion, 151 *

Floating ribs, 25
Floccular fossa, 75
Flower on homologous parts of scapula and ilium,

141, 145.
on ossification of temporal bone, 75
Foutanelles (fons, fountain), 74, 82
Foot, articulations of, 192
bones of, no, 129

compared with hand. 143

in infant, 140

ossification of, 138
Foramen [foro, pierce) of bone, 4
csecum of frontal bone, 38, 69
airot ico-cl inoid, 47
carotid, 42, 68
centralc cochlcfe, 43
dental, inferior, 59
incisor, 52, 72
infraorbital, 50, 63
inlcrcc/ndtjlar, 95
jugular, 68, 71
lacenim anterius, 70

medium, 68, 70

orbitale, 63

posterius, 71
magnum, 31, 68, 71, 82
mastoid, 41, 71
mental, 58, 63
obturator, no, 115
occipital, 31, 68, 71
o|.tic, 47, 63, 70
ovale of hip-bone, 115

of sphenoifl, 47, 65, 70
parietal, 35, 68
rotnndum, 47, 65, 70
sacro - sciatic, great and small, 179,

180
singulare, 43

Foramen — conlinxirxl.

spheno-palatine, 55, 67, 72

spinal, 6, 7, lo, 12

spinosum, 47, 65, 70

sternal, 25, 31

stylo-mastoid, 42, 68

supraorbital, 37, 63, 64

supratrochlear, 95

thyroid, 115

of vertebra, 6

vertebrarterial, 6, 23

of Vesalms, 47
Foramina, condylar, anterior, 33, 68, 71
posterior, 33, 71

of ethmoid bone, 49, 69

intervertebral, 5

sacral, anterior, 14
posterior, 14

of Scarpa, 52

of Stensen, 52
Forearm, articulations of, 169

bones of, 95

compared with leg, 142
ossitication of, 107
Fossa acetabuli, 115

anterior palatine, 52, 67

of bone, 4

canine, 50, 63

coronoid, 94

digastric, 41, 68

digital, 119

glenoid, of temporal bone, 40. 64, 75

guttural, 67

hijpotroclianterica, 123

iliac, III

incisor, of lower jaw, 58
of upper jaw, i;o, 62

infraclavicular, 87

infraspinous, 88

iufratemjioral, 64

intercondylar, 121

jugular, 42

lachrymal, 37, 64

myrtiform, 50, 62

navicular, 47

olecranon, 94

parietal, 35

pituitary, 43

])osterior condylar, 33

jiterygoid, 46, 68

radial, 94

scaphoiil, 47

spheno-maxillary, 65

subscapular, 88

supraclavicular, 87

supraspinous, 88

tem])oral, 64

trochanteric, 119

trochlear, 37

zygomatic, 64, 68
Fossa;, nasal, 71, 82

occipital, sujierior and inferior. 33

Pacchionian, 36, 38, 68

of skull, intei'iial, 68
Fovcola coccy(jea, 178
Frontal {frons, forehead) bone, 36, 80
ossification of, 74

crest, 38

eminence, 37, 82

process of malar bone, 56

sinus, 38, 72, 73, 74, 82

VI

INDEX AND GLOSS AKY TO VOLUME IL, PART I.

Frontal — sulcus, 38

suture, 39, 74
Fronto-parietal suture, 61
Fronto-te7n2wral suture, 84
Furrow of bone", 4

spinal, 18

Gasserian ganglion, depression for, 42
Ginglymus (yiyy\v,uo9, hinge), 149
Girdles, shoulder and pelvic, comparison of, 140
Glabella (dim. of glabra, fem. of glaber, smooth),

37
Gladiolus (dim. of gladius, sword), 25
Gland, Haversian, 181
Glaser, fissure of, 41, 42, 43
Gleuo-humeral ligaments, 167
Glenoid {y^-fivn, sliallowpit of bone ; ddos, shape)
cavitj', 4
of scapula, 90

fossa of temporal bone, 40, 64, 75

ligament, 167
Gliding movement, 151
Gliding joint, 149
Gluteal lines, no

ridge, 121
Gnathic {yvdOos, jaw) index, 85
Groove, bicipital, 93

of bone, 4

carotid, 44, 71

for Eustachian tube, 46, 68

infraorbital, 51, 63

lachrymal, 51, 52, 57, 64

mj'lo-hyoid, 59

obturator. 113

occipital, 41, 68

olfactory, 49, 69

optic, 43

palatine, 67

sacral, 14

spiral, 93

sternal, 25

subcostal, 26

vertebral, of spinal column, 18
of atlas, 8
Grooved suture, 148
Grooves for sinuses, 71
Guttural {guttur, throat) fossa; 67

Hamulak {hamulus, dim. of lianius, hook)
process of sphenoid bone, 47
of lachrymal bone, 57
Hand, articulations of, 172
bones of, 86, 100

ossiHcation of, 108
compared with foot, 143
movements of, 176
Harmonia (apfxovia — Galen, from apfj.6^a), lit

together), 148
Haunch, no
Haversian gland, 181
Head, bones of, 31

homologies of, 79
morphology of, 78
ossification of, 73
typical component parts of, 79
Head of bone, 4

Hiatus (opening, from hio, open) Fallopii, 42, 70

interosseus, 170
Highmore, antrum of, 50, 53, 72, 77
Hinge-joint, 149
Hip-bone, no, 136, 140
Hip-joint, 181

ligaments of, 181
movements of, 183
Homologies, Homology (dij.6s, same ; Aoyos, pro-
portion) of bones of head, 79

of carpus anrl tarsus, 143, 144

of hand and foot, 143

of scapula and ilium, 140, 145

of shoulder and pelvic girdles, 140

of upper and lower limits, 140

of vertebra^, 21
Humeral ligament, transverse, 167
Humei'o-radial index, 99
Humerus (shoulder), 91

compared with femur, 142, 143

ossification of, 107
Hyoid {v, the letter upsilon : el5os, shape) bone.
61, 80
ossification of, 78
Hypapophysis {biro, under; ajjophi/sis), 21, 23

Iliac fossa, in
Ilio-femoi'al ligament, 182
Ilio-lumbar ligament, 178
Ilio-pectineal eminence, 112

line, 112, 113
Ilio-sciatic notch, no, 114
Ilio-trochanteric ligament, 182
Ilium {ilia, fianks), 1 10

homology of, 140, 141, 145

ossification of, 136
Incisor crest, 52

foramen or canal, 52, 72

fissiu'e, 77

fossa of lower jaw, 58
of upper jaw, 50, 62

process of up]ier jaw, 77
Incisura (notch), 4

semilunaris, 25
Incongruent articular surfaces, 1 50
Incus (anvil), 80
Index, alveolar, 85

antibrachial, 99

of breadth of cranium, 84

cephalic, 84

femoro-tibial, 127

gnathic, 85

of height of cranium, 84

humero-radial, 99

nasal, 85

orbital, 85

pelvic, 118

sacral, 15

scapular, 91
Infraclavicular fossa, 87
Infraorbital canal, 51, 63, 77

foramen, 50, 63

groove, 51, 63
Infrapatellar tendon, 184
Infraspinous fossa, 88
Infrasternal depression or fof^sa, 25
Infratemporal crest, 46, 64

fossa, 64
Infundibulum (funnel) of ethmoid bone, 48, 72

INDEX AXD GLOSSARY TO VOLUME IL, PART L

VI 1

Inioii (iVi'ov, nape of neck), 84
Inlet of true pelvis, 115
Innominate bone. Sec Hip-bone.
Interartioular tibro-cartilages and ligaments. Sec
the various joints.

plate, 150
Interchondral articulations, 29, 160
Interclavicular ligament, 164

notch, 25
Interclinoid ligamr/nts, 47
Intercondylar fossa, 121

foranun, 95
Intercostal spaces, 30
Intermaxillary bone, So
Intermedium, 143
Intermetacarpal articulations, 175
Internietatarsal articulations, 196
Internodia (^intcr, between ; iwdus, knot), 105
Interosseous ligaments, ice Ligamknt.s.

ridge of fibula, 12S
of tibia, 126
Inter-parietal hone, 34, 73, 79, 80, 84
Interparietal suture, 61
Interphalangeal articulations of hand, 176

of foot, 197
Interpubic disc, 180
Interspinous ligaments, 153
Intertransverse ligaments, 154
Intertrochanteric lines, 120

ridge, 120
Intervertebral discs, 151

foramina, 5
Intrajurjular process, 34, 71
Inversion of foot, 198
Irregular or mixed bones, 4
Ischio-capsular ligament, 182
Ischium {l<Tx^ov, hip), 113

homology o(, 140, 144

ossification of, 136

Jacobson's nerve, foramen for, 43
Jaw, lower, 58, 80

articulation of, 162
changes in, with age, 61, 78, 82
movements of, 163
ossification of, 78
upper, 50, 80

ossiticatiou of, 77
Joint. Sec Auticul.xtio.n.
Joints, movements of bones in, 151

various forms of. 147
Jugal ijugum, yoke) bones, So
Jugular facet of temporal bone, 42
foramen, 68, 71
fossa, 42
notch, 34
process, 34, 68

Knee-joixt, 183

movements of, iJ
Knee-pan, 124

Lakviu.vth of etlinioi<I, 48
liachryniiil bone, 57, 80

ossification of, 77
crest, 57

Lachrymal fossa, 37, 64

groove, 51, 52, 57, 64

notch, 51

process, 5S
Lambda (the letter A), 83
Lambdoid suture, 61
Lamina cribrosa of ethmoid bone, 48, 49, 69, 82

of temporal bone, 42, 43
Lamince or plates of vertebne, 5, 6, 8, 9, 11, 12
Lateral mass of atlas, 7

of ethmoid, 4S, 49, 76, 80
of sacrum, 14

sinus, groove of, 35, 34, 41, 71
Leg, bones of, no, 124, 127, 138, 142
Length of long bones of limbs, 94
Leptorhine (KenrSs, narrow ; pis, pifos, nose)

skulls, 85
Ligamenta subflava, 153

Ligaments {ligo, bind), accessory, of atlas, 155
occipito-atlantal, 157

acromio-clavicular, 165

alar, 187

alar odontoid, 156

of ankle, 190

annular of radius, 169

of wrist, anterior, 1 74
posterior, 175

astragalo-calcaneal, 192

astragalo-navicular, 193

atlanto-a.xial, 157, 15S

of atlas, transverse, 155

of Bigelow, 1 82

calcaneo-cuboid, 194

calcaneo-navicular, 192

carpal, 173

cari)o-metacarpal, 175

check, 156

chondro-sternal, 160

of coccyx, 178

conjugal, 159

conoid, 165

coraco-acromial, 166

coraco-clavicnlar, 165

coraco-glenoid, 167

coraco-humeral, 167

coraco-scapular, 166

costo-central, 158

costo-elavicular, 164

costo-transverse, 159

costo-xii)hoid, 160

cotyloid, 181

crucial, 1 84

cruciform, 155

cubo-cuneif'orm, 195

of cuboi<l bone, 193, 194, 195

of cnneitbrin bones, 195

deltoid, 190

of elbow, 1 70

of foot, 192

of forearm, 169

glenoid, 167

gleno-humeraj, 167

of hand, 173

of hip-joint, 181

ilio-femoial, 182

ilio-lumbiir, 178

ilio-trochanteric, 182

interartioular, chondro-sternal, 160
costo-centrul^ 159
of liip, 182

intercarpal, 173

Vlll

INDEX AND GLOSSARY TO VOLUME IT., PART I.

Ligaments — continued.
interclavicular, 164
intercliiioid, 47
intermetatarsal, 196
interosseous, of forearm, 169

of leg, 189

inferior, 190
interspinous, 153
intertransverse, 154
iscMo-capsular, 182

of knee-joint, 183
lateral lumbo-sacral, 177
metacarpal, 175

of thumb, 175
metacarpo-plialangeal, 176
metatarsal, 196

transverse, 197
metatarso-phalangeal, 197
morphology of, 150
mucous, 187
naviculo-cuboid, 194
naviculo-cuneiform, 195
oblique, 170
obturator, 180
occipito-atlantal, 157
occipito-axial, 157
odontoid, alar, 156

middle, 156
orbicular, 169
palmar, 174, 176
of patella, 184

lateral, 187
of pelvis, 177
petro-sphenoidal, 43, 47
of phalanges of fingers, 176

of toes, 197
pisi-metacarpal, 174
]:)isi-uncinate, 174
plantar, 194
pterygo-spinous, 47
pubic, 180
pubo-femoral, 182
radio-carpal, 172
radio-ulnar, 169
rhomboid, 164
of ribs, 158
round, of hip, 182
sacro-coccygeal, 178
sacro-iliac, 178
sacro-sciatic, 179
of scapula, 166
scapulo-clavicular, 164
of shoulder-joint, i 66
spino-glenoid, 166
stellate, 158
of sternum, 160
sterno-clavicular, 164
stylo-hyoid, 61, 78, 80, 163
stylo -maxillary, 163
subpubic, 180
suprascapular, 166
supraspinous, 154
suspensory of axis, 1 56
tarsal, 192
tai'so-nietatarsal, 195
temporo-niaxillarj', 162
tibio-fibular, 189
transverse, of atlas, 155

of acetabulum, 182

humeral, 167

of knee, 186

Ligaments, transverse — continued.
metacarpal, 175
metatarsal, 197
trapezoid, 165
of upper limb, 164
vertebral, 152
of wrist, 172
Ligamentum conjugale costarum, 159
colli costEB, 159
nuchffi, 154
jDatellpe, 184
teres of hip-joint, 182
Limb, lower, articulations of, 181
bones of, no

ossification of, 136
upper, articulations of, 164
bones of, 86

ossification of, 106
Limbs, distinctive characters of, in man, 146
homologicai comparison of, 140
homologous bones of, tables of, 144
morphology of bones of, 140
relation of, to axial skeleton, 14 t
Line or Lines of bone, 4
curved, of ilium, no

of occipital bone, 31
gluteal, no
ilio-pectineal, 112, 113
intertrochanteric, 120
oblique, of lower jaw, external, 58
internal, 59
of radius, 98
of tibia, 126
popliteal, 126
spiral, of femur, 120, 121
supracondylar, of femur, 121

of humerus, 93
temporal, 35, 64
trapezoid, 87
Liuea aspera, 120
quadrati, 121
Lingula of lower jaw, 59, 78
sphenoidalis, 44, 70, 76
Long or cylindrical bones, 4
Lumbar vertebraj, 11
Lumbo-sacral ligaments, 177
Lunar bone, loi

homologies of, 143, 144
ossification of, 108

Malar [mala cheek) bone, 55, 80
ossification of, 78

canal, 56, 63

process, 50, 52

tuberosity, 55
Malleolus (ankle ; dim. of malleus, hammer),
external, 127, 138

internal, 127, 138
Malleus (hammer), 80
Mamillary {maviilla, nipple) processes of ver-

tebrse, 12
Mandible {mandibula or onandihulum, jaw,

from manclo, chew), 58, 78, 80
Manubrium (handle) of sternum, 23, 24, 30
Manus (hand), 86
Murgincol 2^rocess of malar bone, 56
Marrow of bone, 3
Mastoid {iu.a(rT6s, nipple ; elSos, form) antrum, 75

cells, 75

foramen, 41. 71

I.NfDEX AND GLOSSARY TO VOLUME IL, PART I.

IX

Mastoid portion of temporal bouc, 39, 41, 75

process, 41, 64, 68, 75, 82
Maxilla (jaw), luferior, 58, 78, 80

superior, 50, 77, 80
Maxillary bone. .See ^Iaxilla.

process of inferior turbinate bone, 58
of palate bone, 54

sinus, 50, 53, 72, 77
Maxilloturbinal bone, 80
Meatus {mco, pass), 4

external auditory, 41, 64, 75

internal auditory, 42, 43, 71

of nose, 48, 49, 72
Mechanism of foot, 197

of pelvis, 180
Meckel's cartilage, 78
Median iTne and jilane, i
^fedulla (marrow; of bones, 3
Megaceplialic (jxeyas, great ; Ki<pa\r). head)

skulls, 83
Megaseme jxeyas ; cr^na, index) orbital

index, 85
Membrane bones of head, 80

interosseous, of forearm, 169
of leg, 189

obturator, 180
Meningeal grooves, 35, 40, 68, 71
^leniscus (nrfvia-Kos — lunula, dim. of tiT\v7).

moon), 150
Mental {mentum, chin) foramen, 58, 63

protuberance, 58

spines, 59

tubercle, 58
Mesatieejihalic {fjLfaaiTaTos, middlemost ; Ke(pa\rj,

head) skulls, 84
Mesatipellic yueffalTaros ; weWa, bowl) pelvis,

118
Mesetlinioid (/xeVos, middle; r]9fj.^s, sieve), 80
Mesocephalic {ueaos ; Ke<\>a\r], head) skulls, ^i"^
Mesogiiathous {fxitros ; yvados, jaw) skidls, 85
Mesorhine [ixiaos ; pi\, pivos, nose) skulls. So
Mesoscapula, 91

Mesosenie [fxea-os ; aritxa, index) orbital iii<lex, 85
^lesosternuni {/xecros ; arifivov, chest), 25
^letacarpo-plialangeal articulations, 176
Metacarpus (jxeTa, beyond ; Kaptros, wrist). 103

articulations of, 175

ossitication of, 109
Metapoi)hysis (fiera ; apophysis), 12, 23
Metasternum {fiiTo. ; aripvov, chest), 25
Metatarso-phalangeal articulations, 197
Metatarsus (fjLird; rap(T6s, instep), 133

articulations of, 196

ossification of, 138
Melopic (p-iTuirov, foreliead) suture, 39
Metopism. 39
Microcft[tlialic (ntKpos, small ; Kfcpu\ri, head)

skulls, 83
Microserne {fuKpis ; o-TJ/xa, index) orbital index, 85
Mixed bones, 4

Morphology (iJiop<f)i\, form ; \6yos, discourse) of
bones of head, 78
of li;.'aments, 150
of limbs, 140
Movement, various kinds of, 151
Movements of ankle-joint, 191
of clavicle, 165
of cll)OW, 172
of foot and toes, 197
of liif), 183
of knee, 188

Movements of lower-jaw, 163

occipito-vertebral, 158

of patella on femur, 188

of pelvis, 180

of radius on ulna, 170

of ribs, 161

of scapula, 165

of shoulder, 169

of vertebral column, 154

of wrist and fingers, 176
Mucous ligament, 187
Mylo-hyoid groove, 59

ridge, 59
Myrtiform [fivprov, myrtle-berry ; foruM, shape)

fossa, 50

Xaiies (nostrils), posterior, 68

Nasal (nasus, nose) aperture, anterior, 62

bone, 56, 80

ossiiication of, 77

crest, 52, 53, 57, 71

duct, 51, 57, 72

fossa; or cavities, 71, 82

index, 85

notch. Sec Notch.

point, S^

process. See Pkocess.

spine. Sec Spine.
Nasion, 83

Navicular {'iiavicula, small ship or boat) bone of
foot, 131, 138
articulations of, 192, 194, 195
homology of, 144

fossa, 47
Naviculo-cuboid articulation, 194
Naviculo-cuneiform articulation, 195
Neck of bone, 4
Neural [vtvpov, uerve) arches of vertebite, 5, 21

canal, 6

spines of vertebra, 5, 21
Neuro-central S5''nchondrosis, 19
Nose, fosste or cavities of, 71, 82

meatuses of, 48, 51, 53, 72

septum of, 71
Notch, ajromio-scapular, 90

of bone, 4

clavicular, 25

coraco-scapular, 90

cotyloid, 115

ethmoidal, 36

ilio-.sciatic, no, 1 14

interclavicular, 25

intercondylar, 121

jugvilar, 34

lachrymal, 51

nasal, of frontal bone, ",7
ol uppci- jaw, 50

popliti'al, 126

pterygoid, 47

sacro-sciatic, 1 16

scapular, great, 90

sciatic, no, n4

sigmoid, 59

splicno-palatine, 55

supraorbital, 37, 63, 64

suprascapular, 90

suprasternal, 25
Notches of vertebrie, 5

X

INDEX AND GLOSSARY TO VOLUME II., PART I.

Nucha (from Arabic nuqrah, hollow at nape of

neck — Hyrtl), ligament of, 154
Number of bones, 4

Obelion {60e\us, arrow ; o^eAaia pacpij, sagittal

suture), 83
Oblique ligament, 170

sacro-sciatic ligament, 179
Oblique lines of lower jaw, 58, 59
of radius, 98
of tibia, 126
Obturator crest, 113
groove, 113
foramen, no, 115
membrane or ligament, iSo
Occipital [occiput, back of head) bone. 31, 79
ossitication of, 73
crest, external and internal, 32, 33
foramen, 31, 68, 71
fossse, 33
groove, 41, 68
point, 83

protuberances, 31, 33
Occipito-atlantal ligaments, 157
Occipito-axial ligaments, 157
Occipito-mastoid suture, 62
Occipito-parietal suture, 61
Odontoid (oSo'us, gen. o^ovtos, tooth ; eI5os,
shape) ligaments, 156
process, 8, 20, 21
Olecranon {aiAfKpavov. point of elbow ; from
w\4vri, olbow ; Kpavlov, head), 95
fossa of, 94
Olfactory groove, 49, 69
Olivary eminence, 43, 70
Ophryoir {ocppvs, eyebrow), 83
Opisthion (dniaeios, hinder), 84
0])isthotic {6iri<Td€v, behind ; ovs, gen. irdj, ear)

portion of temporal bone, 75
Optic foramen, 47, 63, 70

groove, 43
Orbicular ligament, 169
Orbit [orhita, circle), 63
Orbital arch, 37

canals, internal, 38, 49, 64, 69
index, 85

plate. ISee Plate.
process. See Pj:oce.ss.
wing of sphenoid, 45, 76, 80
Orbitosphenoid, 76, 80
Orthognathous [hpQos, upright ; yvados, jaw)

skulls, 15
Os acetabuli, 136
calcis, 129

articulations of, 192, 193
homology of, 144
ossification of, 138
centrale, 103, 143
coxEe (bone of hip), no
innominatum, no
linguas, 61
magnum, 102, 108

homology of, 144
planum, 48
pubis, no

homology of, 140, 144
ossification of, 136
trigonwm, 133, 144
unguis, 57

Ossa sv/prasLemalia (bones above sterniTm), 25
Ossa suturarum, 62
Os.sa triquetra (triangular bones), 62
Ossification, 3

of bones of head, 73

of bones of lower limb, 136

of bones of upper limb, 106

of ribs and sternum, 30

of vertebrse, 19
Osteology {oariov, bone ; k6jos, discourse), 3
Outlet of pelvis, 116

Pacchionian^ fossa-., 36, 38, 68
Palatals, 80
Palate bone, 53, 80

ossification of, 77

hard, 52, 53, 67

plate of palate bone, 53, 72

superior maxilla, 50, 51', 72
Palatine canal, accessory, 54, 67
anterior, 52, 67
posterior, 51, 54, 67
small, 54, 67

fossa, anterior, 52, 67

groove, 52, 67

spine; 53
Palato-maxillary canal, 51, 54, 67
Palmar ligaments, carpal, 1 74
carpo-metacarpal, 175
metacarpal, 175
Paramastoid {irapd, beside ; mastoid process)

process, 35
Parapo]ihysis {irapd ; apophnsis), 23
Parietal bone, 35, 80

ossification of, 74

eminence, 35, 82

fissure, 74

foramen, 35, 68

fossa, 35
Parieto- mastoid suture, 62
Patella (dish or plate), 124, 138, 144

ligament of, 1S4
lateral, 187

movement of, on femur, 188

ossification of, 138
Pectoral ridge, 93
Pedicles of vertebra, 5
Pelvic girdle, 140

index, 118
Pelvic and thoracic limbs, homologous bones

in, 142
Pelvis (basin), no, 115

articulations of, 177

axis of, 1 1 7

brim or inlet of, 115

compared with shoulder, 140

differences in the sexes, 118

dimensions of, 118

distinctive characters of, in man, 118, 145

in child, 137

lower or true, 116

mechanism of, 180

outlet of, 116

position of, 117

upper or false, 116
Periotic (Trept, around ; ovs, dios, ear) portion of

temporal bone, 75, 80
Periosteum (Te/L,/ ; oar^ov, bone), 3
Peroneal {ivepopr], pin of buckle, fibula) bone, 127

spine, 130

IXDEX AND GLOSSARY TO VOLUME IL, PART L

XI

Petro-basilar fissure, 68

Petro-mastoid portion of temporal bone, 75, So

Petro-sphenoidal tis^sure, 6S

ligament, 43-47
Petro-.sqiXiimons fissure, 42
Petrosal 2>roeess 01 sphenoid, 44

siipcricr, 47
Petrous (irirpa, rock) portion of temporal bene,

39. 41, 75-, 80, 82
Phalanges (<^oAa7|, column of soldiers, originally
used for the series of phalanges or
infcrnvdia ; or possibl}" from <pa\avi_,
cylindrical roller) of fingers, 105
articulations of, 176
ossification of. 109
of toes, 135

articulations of, 197
ossification of, 139
Pharyngeal tubercle, 34
Pilastercd fnniir, 123
Pisi-metacarpal ligament, 174
Pisi-unciuate ligament, 174
Pisiform {pisum. pea ; foriiut, shape) bone, loi,
144
articulation of, 174
ossification of, loS
Yitnitary {pi till ta, phlegm or mucus) fossa, 43, 70
Pivot-joint, 149
Plagiocepbalv (TrAa7ios-. obli(iue ; KecpaAr], head),

86 "^

Plantar ligaments, 194
Plate, cribriform, 48, 49. 69, 71
orbital, of ethmoid, 48, 63

of frontal bone, 36, 03. 69
palate, of palate bone, 53, 72

of superior maxilla, 52, 72
pterygoid, internal and external, 46, 47,
. 64, 76, So
tympanic, 41, 75. 80
vertical, of ethmoid, 48. 71, 76, 80
of palate bone, 53, 63, 72
Platycnemic {irKarvs. broad : Kfrtfj-r], tihia) tilnc,

127
Platypeliic (ttAotuj ; ■:tihK%, bowl) pelvis, 118
Platyrhine (ttAotus ; pis, fnvos, nose) skulls, 85
Point, alveolar, 83
auricular, 84
nasal, 83
occi))itai, 83
spinal or subnasal, 83
supraorbital, 83
Poyditeul (pojjlcs, liam) line, 126
notch, 126
surface of femur, 121
Postauditory process, 74
Postaxial [post, behind ; axis) borders of limbs,2,

142
Postglenoid process, 41
Postscapula, 91
Postsjilienoid, 75
Praeaxial { j/ru:, before ; axis) borders of limbs, 2.

142
Prehallux, 144
Premaxillarv bone, 77, 80
l'rei>ollex, 144
Prescajiula, 91
Presplienoid, 75, 80
Presternum, 24
Process of bone, 4
acromion, 90
alar, of ethmoid, 48

Process of bone — continued.

alveolar, of su})erior maxilla, 50, 52
angular, of frontal bone, 37
auditory, external, 41
basilar,' 31, 34, 67
clinoid, anterior, 45
middle, 47
posterior, 44
cochleariforui, 42
coracoid, 90, 106, 140
coronoid, of lower jaw, 60, 64, 78

of ulna, 95
descending, of lachrymal bone, 57
ensiform, 23, 25

ethmoidal, of inferior turbinate bone, 58
falciform, 179
frontal, of malar bone, 56
hamular, of lachrymal bone, 57

of sphenoid bone, 47
inlrajugular, of nccij^ital bonr, 34, 71
jugular, of occipital bone, 34, 68
lachrymal, of inferior turbinate bone, 58
malar, of upper jaw, 50, 52
marginal, of mnlar hone, 56
mastoid, 41, 64, 68, 75, 82
maxillary, of inferior turbinate bone, 58

of palate bone, 54
nasal, of frontal bone, 37
of u[>jicr jaw, 50, 51
odontoid, 8, 20, 21
orbital, of malar bone, 56, 63

of palate bone, 53, 54, 63, 65
palate, of upper jaw, 50, 52, 72
paramastoid, 35
petrosal, of sphenoid, 44

superior, 47
postauditory, 74
postglenoid, 41
pterygoid, 43, 46, 65
pyramidal, of jialate bone, 53, 54, 65, 68
.sphenoidal, of palate bone, 53, 54, 65, 72
spinous, of sphenoid bone, 45
.styloid, of fibula, 127
of radius, 99

of temporal bone, 42, 68, 75, 80
of ulna, 97
supracowlylar, 94
temporal, of malar bone, 56
turbinate, su))erior and interior, 48, 49
uncinate, of ethmoid bone, 48, 53
ungual, of phalanges, 105
vaginal, of sjihenoid, 47

of temi)oral bone, 42, 68
xiphoid, 25
zygomatic, 40
Processes, accessory, of lumbar vertebroe, 11, 23
cajiitular, of dorsal vertebra;, 23
mamillary, of lumbar vertebrre, 12, 23
tubercular, of dorsal vertebra', 23
of vertebra-, articular, 5, 6, 7, 8, 9, 11
.spinous, 5, 6, 7, 8, 9, 11
tran.sverse, 5, 6, 8, 9, 11, 16
serial relations of, 21, 23
Processus cochlearil'ormis (spoon-shaped ]iro-
ce.ss), 42
dentatus, 8
Prognathous (irpd, fijrward ; yfdGos, jaw) skulls,

85
Promontory of .sacrum, 13, 115
Pronation (prouux, having tiie face downward),

170

Xll

INDEX AND GLOSSAEY TO VOLUME II., PAUT I.

Pronator ridge, 97

Prootic (jp6, before ; ovs, gen. a-ro's, ear) centre,

75 . . ,

Protuberance, occipital, external, 31

internal, 33, 70

mental, 58

Pseudo-sacral vertebrse, 23

Pterion (jrrepov, wing), 84

Pterotic centre, 75

Pterygoid (-Krepv^, Aving ; el5os, shape) bones, 76,

80

canal, 47

fossa, 46, 68

notch, 47

plates, 46, 47, 64, 76, 80

process, 43, 46, 65

tubercle, 47

Pter3'go-maxillary fissure, 65

Pterygo-palatine canal, 47, 54, 65

Pterygo-spinous ligament, 47

Pubic {p^ibes, hair of genitals, &c., which a]5pears

at the period of " puberty ") articulation,

180

bone. See Os Pubis.

crest, 113

ligaments, 180

spine, 113

Pubo-femoral ligament, 182

Pyramidal bone, loi

. homology of, 143, 144

ossification of, 108

process of palate bone, 53, 54, 65, 68

Radial fossa, 94
Kadiale, 143

sesainoideum, 144
Radio-carpal articulation, 172
Radio-ulnar articulations, 169
Radius (ray, or spoke of wheel), 97

homology of, 142, 144

movement of, on ulna, 170

ossification of, 107
Ramus (branch ; pi. rami) of ischium, 113

of lower jaw, 59

of pnbic bone, 113
Recess, spheno-ethmoidal, 72
Retinacula of hip, 183

Rhomboid (p6/j.^os, rhomb ; el5oj, sbape) liga-
ment, 164
Ribs, 25

articulations of, 158

cartilages of, 25, 28

movements of, 161

ossification of, 31
Ridge of bone, 4

gluteal, 121

interosseous, of fibula, 1 28
of tibia, 126

intertrochanteric, 120

mylo-hyoid, 59

pectoral, 93

pronator, 97

superciliary, 37, 82

su]jinator, 97
Ridges, supracondylar, 93
Rostrum (beak) of sphenoid bone, 44
Rotation, 151

Rotula (dim. of rota, wheel), 124
Round ligamentof hip, 182

Saceal canal, 1 5

cornua, 14

foramina, 14

index, 15

vertebrse, 5, 13, 20, 21
pseud 0 and true, 23
Sacro-coccygeal articulation, 178
Sacro-iliac articulation, 1 78
Sacro-sciatic foramen, 179

ligaments, 117, 179

notch, 116
Sacro-vertebral angle, 18

articulation, 177
Sacrum {os sacrum, translation of Uphv octtovv,
great bone ; also called Upos airovSuXos,
great vertebra, e.g., in Galen), 5, 13

articulations of. 177

ossification of, 20
Saddle-joint, 149
Sagittal {sagittu, arrow) suture, 61

fontanelle, 74
Scalene tubercle, 27
Scaly suture, 147
Scaphocephaly {(TKd(pTj, boat ; necpaXri, head),

86
Scaphoid {aKd<pr) ; eidos, shape) bone of foot,

131

bone of hand, 101, 108

homology of, 143, 144

fossa, 47
Scapula [scaptdcc, back of shoulders), 87

compared with ilium, 140, 145

ligaments of, 166

ossification of, 106
Scapular index, g'l

notch, great, 90
Scapulo-clavicular articulation, 164

arch, 164 •

Scarpa, foramina of, 52
Schindylesis {ffX'ySv\eco = ax'^^w, split), 148
Sciatic notches, no, 114
Sella Turcica (Turkish saddle), 43, 70
Semilunar bone, loi, 108

homology of, 143, 144

fibro-cartilages of knee, 185
Sense-capsules or cavities, 81
Septum nasi, 71

sphenoidal, 43
Serial homology of vertebrae, 2 1
Serrated {serra, saw) suture, 147
Sesamoid {a'fia-aiu.ov, kind of small grain ; dSos,
shape) bones, 4

fibular, 144

of foot, 135, 197

of hand, 105, 176

radial, 144

tibial, 144

ulnar, 144
Sexual differences in skull, 82
in femur, 123
in pelvis, 118
in sacrum, 15
Shin-bone, 124
Short bones, 4
Shoulder, articulation of, 166

compared with pelvis, 140

ligaments of, 166
Sigmoid (C, form of letter aiyij.a, sigma ; eiSos,
shape) cavity of radius, 99

cavities of ulna, 95

notch of lower jaw, 59

INDEX AXD GLOSSARY TO VOLUME IL, PART L

Xlll

Sinus (hollow) of bone, 4

frontal, 38, 72, 73, 74, 82

maxilhiry (or aiitiiiin), 50, 53, 72, 77

sphenoidal, 43, 72, 73, 76

tarsi, 193
Sinuses, air, in bones of head, 71, 82

ethmoidal, 48, 72, 77
Skeleton (c/ceAAo), dr}'), 3

adapted to erect attitude, 145
Skull, anterior region of, 62

as a whole, 61

base of, external, 67
internal, 68

bones of, 31

difference of, from animals, 78, 145

differences in, from age, 82
race, 82
sex, 82

external surface, 62

forms of, 82

irregular, 85

fossse of base of, 68

grooves for bloodvessels in, 71

homologies of, 79

interior of, 68

lateral region of, 64

measurement of, 82

morpliology of, 78

ossiftcation of bones of, 73

superior region of, 62

sutures of, 61

vertebrate theory of, 81
Spaces, intercostal, 30
Spheno-ethmoidal recess, 72
Sphenoid {(^(pw, wedge ; dSos, shape) bone, 43,
80

articulations of, 43

ossitication of, 75
Sphenoidal crest, 44

fissure, 47, 63, 70

foramen, 76

process of j)alate bone, 53, 54, 65, 72

septum, 43

sinus, 43, 72, 73, 76

spongy bones, 44, 76, 80

turbinals, 80

turbinate hones, 44
Sphenomaxillary fissure, 63, 65

fossa, 65
Spheno-palatine foramen, 55, 67, 72

notch, 55
Spheno-parietal suture, 62
Sphenotic {(r<p-f)v ; ols, gen. wt6s, ear), 76
Spinal canal, 6

furrow, 18

point, 83
S[>ine. See V^ertebral Column.
Spine of bone, 4

ethmoidal, 44

of ilium, anterior and posterior, 1 10

of ischium, 114

na.sal, of frontal bone, 38, 71
of palate Vjoiie, 53
of ui)per jaw, 50, 62

neural, 5

palatine, 53

peroneal, 130

ot OS pubis, 1 13

of scapula, 89

of tibia, 126

trochlear, of frontal bone, 39

S^nnes, mental, 59

Spino-glenoid ligament, 166

Spinous processes of vertebrje. See Processes.

of sphenoid bone, 45
Spiral groove, 93

line of femui', 120, 121
Splenial bone, 78

Spongj' bones, ethmoidal, 49, 72, 80
inferior, 58, 72, 78, 80
sphenoidal, 44, 76, 80
Squamosals, 80

Squamous (squama, scab) portion of temporal
bone, 39, 74, 80

suture, 62, 147
Squamo-zygomatic, 39, 74, 80
Stapes (stirrup), 80
Stellate ligament, 15S
Stensen, foramina of, 52
Stephanion (o-Tt^avos, crown), 84
Sternal fo7Yi mm, 25, 31

furrow or groove, 25

ribs, 25
Sterno-clavieular articulation, 164
Sternum (uTepvov, breast or chest), 23

cleft, 25

ligaments of, 161

ossification of, 30

varieties of, 25
Stylo-hyal, 75, 80

Stylo-hyoid ligament, 61, 78, 80, 163
Styloid {ffTvKos, .style or pen ; elSos. shape)
process of fibula, 127
of radius, 99

of temporal bone, 42, 68, 75, 80
of ulna, 97
Stylo-mastoid foramen, 42, 68
Stylo-maxillary ligament, 163
Subacromial bursa, 168
Subcoracoid ossification of scapula, ic&
Subcostal angle, 29

groove, 26
Subnasal point, 83
Subpubic arch, 116, 118

ligament, 180
Subscapular fossa, 88
Sulcus of bone, 4

frontal, 38
Superciliary {siqyerciliicrn, eyebrow ; super,

above ; cilium. eyelid) ridge, 37, 82
Supination {supinus, lying on back), 170
Supinator ridge, 97
Supraclavicular fossa, 87
Supracondylar lines of temur, 121

2)rocrss, 94

ridges of humerus, 93
Supramastoid crest, 40
Sujiraoccipital bone, 73, 79
Supraorliital foramen, 37, 63, 64

notch, 37, 63, 64

point, 83
Suprascapular cartilage or bone, 107

liguiK'nt, 166

notch, 90
Supraspinous fossa, 88

ligament, 154
Suprasternal notch, 25
Supratrochlear foramen, 95
Suspensory ligaments. Sec Ligamrnts.
Su.stentaculum tali (suj)i)ort of astragalus), 129
SuTURE.s OR Suture Undura, seam), 61, 147

closure of, 62 4

XIV

INDEX AND GLOSSARY TO VOLUME II., PART I.

Sutures or Suture — continued.

coronal, 6i

forms of, 147

frontal, 39, 62, 74

fronto-parietal, 61

fronto-tem2Mral, 84

interparietal, 61

lambdoid, 61

metopic, 39

occipito-mastoid, 61

occipito-parietal, 61

parieto-mastoid, 62

sagittal, 61

spheno-parietal, 62

squamous, 62, 147

temporo-parietal, 62
Symphysis (cru;', Avith, together ; (pvai, grow), 148

of lower jaw, 58

pubis, 113, 180
Synarthrosis {(rvuapdpaxns — Galen, immoveable

articulation : from auv ; apdpou, joint), 147
Synchondrosis {avy ; x('"^^pos, cartilage), 147
Syndesmosis {awSeafJ-os, ligament), 148
Synostosis (trvv ; otrreov, bone), 85, 147
Synovial bursa, subacromial, 168
Synovial membhanes and cavities, 148

acromio-clavicular, 165

of ankle, 191

of atlas, 155, 156

of axis, 155, 156

carpal, 1 74

chondro-sternal, 158, 159

costo-central, 158

costo-transverse, 159

of elbow-joint, 172

of hip, 183

interchondral, i6o

of knee-joint, 187

metacarpal, 175

metacarpo-phalangeal, 176

metatarsal, 196

metatarso-plialangeal, 197

radio-carpal, 173

radio-ulnar, 169

of shoulder-joint, 168

sterno-clavicular, 164

tarsal, 193, 194, 195

tarso-meta tarsal, 196

of temporo-maxillary articulation, 163

tibio-fibular, 189, 190

of vertebra, articulating, 153

Tables of skull, 68
Tabular bones, 4

portion of occipital bone, 3 1
Talus (die). See Astragalus.
Tarsal articulations, 192
Tarsalia, 143

Tarso-metatarsal articulations, 195
Tarsus (rapaos, upper surface of foot), 1 29

bomologies of, 143, 144

ligaments of, 192

movements of, 197

ossification of, 138
Tegmen (cover) tympani, 42
T'emporai {tempora, temples) bone, 39, 80

articulations of, 39,

162
ossification of, 74

canal of malar bone, 56, 64

Temporal crest, 37, 64

fossa, 64

lyiPS ',5, 64

process of malar bone, 5(5

surface of frontal bone, 37
of parietal bone, 35
of sphenoid bone, 46

wings of sphenoid, 45
Temporo-maxillary articulation, 162
Temporo-parietal suture, 62
Tendon, infrapatellar, 184
Terms, descriptive, i
Thigh-bone, 11 S
Thoracic vertebrae, 9
Thorax [Odpai,, breast-plate), 23

as a whole, 29, 145
Thyrohyals, 80
Thyroid foramen, 115
Tibia (pipe or flute), 124

homology of, 142, 144

ossification of, 138
Tibiale, 143

sesamoideum, 144
Tibio-fibular articulations, 1S9, 190
Toes, bones of, 135, 138

movements of, 198
Torcular (wine or oil-press, transl. of Xrivoi of

Herophilus, meaning cistern) Herophili, 33
Torsion of fen'iur, 123

of humerus, 94

of tibia, 127
Torus (elevation) occipitalis trcmsvcrsiis, 34
Tractus spiralis foraminulentus, 43
Transverse carpal articulation, 173

ligament. Sec Ligament.

processes of vei'tebrie, 5, 6, 8, 9, 11, 16,
21, 23

tarsal articulation, 194
Trapezium {rpaTreQov, geometrical figure, dim.

oi' rpdire^a, table or board), 102, 108, 144
Trapezoid bone, 102, 108, 144

ligament, 165

line, 87
Trochanter (rpoxavTitp, runner, that which re-
volves, connected with TpoxaC<^ or rpoxa^,
run along, revolve), great, 119

small, 120

third, 123
Trochanteric fossa, 119
Trochlea (rpoxtAia, pulley) of humerus, 94
Trochlear fossa, 37

surface of femur, 121, 188
Trochoides (rpoxo-el'5i]s, wheel-like), 149
True ribs, 25

vertebrae, 5
Trunk, articulations of, 151
Tubercle of bone, 4

adductor, 121

of astragalus, 131

conoid, of clavicle, 87

deltoid, of clavicle, 87

of femur, 119

mental, 58

of OS calcis, 129

pharyngeal, 34

pter3'goid, 47

of quadratus, 120

of radius, 99

scalene, 27

of scaphoid bone, 10 1

of tibia, 126

INDEX AND GLOSSARY TO VOLUME IL, PART I.

XV

Tubercle of bone — ccntinued.

of twelfth dorsal vxtelira, exteriial, iiifeiior
and superior, 1 1

of zygoma, 40
Tubercular processes of dorsal vertebra?, 23
Tuberosity of bone, 4

of cuboid, 132

of humerus, 91

bicipital, 9S

of femur, 122

of fifth metatarsal bone, 135

of first metatarsal bone, 133

of ischium. 113

malar, 55

of olecranon, 95

of OS calcis, 129

of palate bone, 53. 54

of ribs, 26

of scaphoid, 131

of superior maxillary bone, 50

of tibia, 124, 126

of ulna, 95
Turbinate (coiled, from turbo, whirl) bones.
Sec Spon{;y Bones.

crest, 51, 53

processes, inferior and superior, 48, 49
Tj'uipanic (tym2)anum, drum of ear) bone, 74,
80

plate, 41, 75, 80

rinc.', 75
Tympanoh}-al, 75, 80
Tympanum, 41

Ulxa (d!A.eV7j, elbow), 95

compared witli Ijones of leg, 142

ossification of, 108
Ulnare, 143

.sesamoideum, 1/^4
Unciform {tincus, hook ; forma, shape) bone,

103, 108, 143
Uncinate (imcus) process of ethmoid bone, 48,

53
Ungual {unguis, nail) phalanges, 105, 109

Vaginal (vagina, sheath) process of sphenoid
bone, 47 ■
of temporal bone, 42, 68
Venter (belly) of scapula, 88
Vertebra dentata, 8
prominens, 9

VlHTEBi!.E (rcrto, turn), 5
cervical, 6
first, 7
second, 8
seventh, 8
coccygeal, 16
dorsal, 9
false or fixed, 5
general characters of, £
groups of, 6
homology of, 21
lumbar, 11
moveable, 5
number of, 5

varieties in, 12
ossification of, 19
pseudo-sacral, 23
sacral, 13
thoracic, 9
true, 5
Vertebral column, 5

articulations of, 151
as a whole, 18
in child and in adult, 145
curves of, 18
movements of, 154
ossification of, 19
grooves, 18
groove of atlas, 8
notches, 5
Vertebrai-terial foramen, 6
Vertebrate theory of skull, 81
Vertical plate of ethmoid, 48, 71

of palate, 53, 65, 72
Vcsalius, foramen, of, 47
Vestibule, aqueduct of, 42
Vidian canal, 47, 65, 70
Vitreous {vUrum, glass) table of skull, 68
Vomer (ploughshare). 55, 71, 80
ossification of, yj

Wings of .sphenoid bone, 43

"Wormian bones, 62, 68, 74

Wrist, articulation of, 172

movements of, 176

45

Xii'llisTEiiNUJi Qicpos, sword; ar^pvov, breast),
25

Zygavophyses (Cvy, root of (evyw/n, yoke, or

join together ; ajjophij^is), 5, 21
Zygoma (cross-bar or bolt, from root above

given), 40
Zygomatic arch, 64
fossa, 64

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