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AIDS

ANATOMY,

GEORGE BROWN, M.R.C.S., L.S.A.

Late Demonstrator of Anatomy at Westminster Hospital

Medical School; Gold Medalist, (ISTS'i Charing

Cj'oss Hospital : formerly Prosector of Anatomy at

the Royal College of Surgeons of England, Sfc.

LONDON :

BAILLIERE, TINDALL & COX., King William St., Strand.

DUBLIN :

FANNIN & CO., Grafton Street.

EDINBURGH :

MACLACHLAN & STEWART, South Bridgb.

GLASGOW :

A. & W. STENHOUSE, College Gate.

1876.

/^5 . ^ . ^^ .

LONDON :

BsFBDVTBD FBOM THE STUDENTS' JOUKNAL, bt
BAILLIERE, TINDALL & COX.

PREFACE.

The anatomical memoranda to be found in the fol-
lowing pages, and which I have designated *' Aids to
Anatomy" have been reprinted from The Students'
Journal and Hospital Gazette at the suggestion of
many readers of that journal, who were desirous of
possessing the "Aids" in a collected and permanent
form.

If what is here given be favourably received by Stu-
dents of anatomy, I shall be encouraged to extend the
series at some future time ; at present I am content to
launch this small and unpretending volume and await
the verdict of those for whom it is intended.

GEORGE BROWN.

GOLEBBOOKE Row, LoNDON, N.

CONTENTS.

FAOB.
Introductoey 1

I. Anterior Triangle of the

Neck 3

II. Posterior Triangle of the

"^Qcfs. 7

III. Snb.Occipitfa Triangle 9

IV. Triangle in front of the

Blbowjoint 9

V. Scarpa's Triangle 10

YI. Hesselbach's Triangle 10

VIi: The Axilla 11

Yin. The TriangiQar Space

at the npper part of
the Arm 18

IX. The Popliteal Space 13

X. Stmctnres on the Masse-

ter Mnscle 14

XI. Stractores on the Mylo-

Hyoid Mnscle 14

Xn. Stmotores beneath the

Mylo-Hyoid Mnscle . . 14
XIH. Stmctnres on the Hyo.

Glossns Mnscle 16

XIV. Stmctnres beneath

the Hyo^lossns Mas.

ole 16

XV. stmctnres beneath the

SterncCleido-Mastoi-
dens 15

XVI. Stmctnres beneath the

Deltoid Mnscle 16

XVII. Stmctnres beneath
the Glutens Maximna
Muscle 17

Xvni. Structures passing
through the superior
aperture of the Thorax 18

XIX. The Mediastinum 18

XX. Structures constituting

Boot of Lung 20

XXI. Structures in concavi.

ty of, and behind
Arch of Aorta :. 21

XXn. Structures between
the clavicle and First
Rib 21

XXm. The Costo.Coracoid

Membrane 22

XXIV. Relations of the Tra-

jchea in the Neck 22

PAGE.

XXY . Relations of the Pros.

tate Gland 23

XXVI. Structures passing

through Inlet of Pel.

^^ vis 23

XXVn. Viscera covered or

invested by Perito.

neum 24

XXVni. Contents of Spinal

Canal 25

XXIX. The Soft Palate 26

XXX. Structure of the Eye.
lids 26

XXXI. The Inguinal Canal
and coverings of In.
guinal Hernia 27

XXXn. The Spermatic Cord 28
XXXm. The Craral Canal

and coverings of Fe.

moral Hernia 29

XXXIV. The Parotid Gland 30

XXXV. The Cranial Nerves 31
XXXVr. The Olfactory Nerve 32
XXXVII. The Optic Nerve... 33
XXXVin. The Third Pair

ofNerves 34

XXXIX. The Fourth Pair of

Nerves>>> . •• .... •• •• 36
XL. The Fifth Pair ofNerves 36
XU. The Ganglia of the

Fifth Pair of Nerves 47
XLH. The Sixth Pair of

Nerves ' 61

XXUn. The Seventh Pair

ofNerves 52

„ (A) The Portio Dura

or Facial Nerve 62

„ (B) The Portio Mollis
or Auditory Nerve ... 57
XMV. The Eight Pair of

Nerves

„ (A) The Glosso-Pharjm.

geal Nerve

„ (B) The Pneumogas.

trie Nerve

„ (C) The Spinal Acces.

sory Nerve

XLV. The Ninth Pair of

Nerves 63

AIDS TO ANATOMY.

There are some students who will ask — and with
good reason — " What, in the name of all that is rational,
is the use of adding one jot or tittle to our anatomical
literature ?" " Have we not Quain, Ellis, Gray, Holden,
Wilson, Heath, and a host of other works, all of them
masterpieces in their way, and any one of them equal
to carrying us through any ordinary examination T I
confess that it is difficult to find an answer to these
questions, especially since I cannot even pretend to have
made a single anatomical discovery, or to have happened
on any one anatomical fact, that has not been treated of
by one or more of the above observers. But it is quite
possible to present these facts to the learner in a dif-
ferent form, and to group the more important in such a
manner that the mind may more readily grasp and re-
tain them. This, then, is the object of these papers.

Anatomy is not generally considered to be an in*
teresting subject, or one easy to master, and often the
beginner is overwhelmed by the magnitude of the task
before him, and despairs of 'ever becoming familiar with
its details. This feeling, though very natural, is scarcely
warranted if a proper estimate of the difficulties to be
met be formed. For, after all, anatomy is not more

difficult to the medical student than the study of
geography to the school-boy. He has to learn all about
the various countries of the world, their names, situation,
boundaries, and divisions, their mountains and valleys, the
rivers running through them, together with their origin,
size, branches, communications, and terminations. In
the same manner, the student of anatomy has to learn
how the body is divided into regions and spaces, their
names, situation, boundaries, and contents, the vessels
and nerves met with in these spaces, together with
their origin, size, branches, communications, and ter-
minations. These particulars respecting the regions
and spaces into which the human body is divided are
among the things that a student must know by heart
before presenting himself for an anatomical examina-
tion, should he wish to pass with credit. It was to fa-
cilitate the acquisition of this knowledge, in my own
case, that these "Aids ' first obtained a place in my
note-book, and, as I found them of assistance, I may
hope that they will prove a help to others. And here
let me disclaim any intention to palm off the " Aids "
as original. Some were copied from anatomical works,
others from the slates in the dissecting rooms I have
visited, and for many I am indebted to gentlemen con-
nected with the dissecting rooms of other hospitals,
whilst a few only can be said to be original. Those
who have been subscribers to The Stttpbitts' Journal
from the commencement will observe that some of the
*' Aids " were pubhshed in Its early issues ; but as I am
told by the publishers that most of these numbers are
out of print, and are often asked for by students pre-
paring for << College" examinations, they are now
republished in a permanent form.

It may be as well to caution those who are on the look-
out for a "royal road" to anatomical knowledge
against imagining that the "Aids" will render dis*

section unnecessary. No greater mistake can be made.
In anatomy, nothing can ever take the place of actual
dissection, and he who ventures to present himself at
the College of Surgeons' " Primary " with nothing more
than book knowledge will assuredly pay the penalty.

As before remarked, the human body is divided into
a number of regions and spaces, which are of the
highest importance, both anatomically and surgically,
and it is not surprising that great stress is laid on
them at surgical examinations. Among the more im-
portant spaces are the triangles of the neck, Scarpa's
triangle, the popliteal space, and the axilla, the con-
sideration of wluch will now occupy our attention.

I. — ^Ths Antebiob Tkiakole of the Nsok.

The anterior triangle of the neck is the space in
firont of the anterior border of the stemo-mastoideus
muscle, and is limited by the following boundaries : —

In Front, — Median line of the neck from the chin
to the top of the sternum.

Bdwnd. — ^The anterior border of the stemo-
mastoideus.

Above. — ^Body of lower jaw, and a line continued
from its angle to the mastoid process of the
temporal bone, forming the hose of the
triangle. [The apenu is at the top of the
sternum.]

The Floor, — ^The floor is formed by the following
muscles: — Stemo-thyroideus, sterno-hyoideus
thyro-hyoideus, inferior and middle constric-
tors of the pharynx, the anterior belly of the
digastricus, stylo-hyoideus, mylo-hyoideus, and
hyo-glossus. The floor is crossed by the an-
terior belly of the omo-hyoideus and the
posterior belly of the ^^%&^'k^>'^'^^«^ ^s^isir

diyide the anterior triangle into three smaller
ones, viz. — (a) Inferior carotid triangle ;
(6) Superior carotid triangle ; (c) Svh-maxil^
lary triangle,

Boof, — The space is covered in by integument,
superficial fascia, platysma myoides, and deep
fascia. Between the layers forming the roof
are the cutaneous branches of the facial and
superficial cervical nerves.

The contents will be enumerated in the description
of the subdivisions (a), (6), (c).

(a). — The Inferior Carotid Triangle.

This triangle is the lowermost subdivision of the
anterior triangle of the neck, and has the following
boundaries : —

In Front. — Median line of the neck.

Behind, — Anterior border of the stemo-mastoideua.

Above, — Anterior belly of the omo-hyoideus.

The muscles met with on the floor of the space are
the stemo-hyoideus and stemo-thyroideus,
and it is covered in by integument, superficial
fascia, platysma myoides muscle, and deep
fascia.

CoNTElfTS:

As usually dissected, this space contains the
following structures : —

Thjrroid gland, lower part of larynx and trachea.
Veins. — Internal jugular and inferior thyroid.
Arteries. — Common carotid and inferior thyroid.

Nerves. — Pneumogastric, reourrent laryngeal,
descendens noni, commiinicans noui, and
sympathetic.

In order to expose the above structures it is neces-
sary to turn aside the stemo-hyoideus and stemo-
thyroideus, and a portion of the sterno-mastodeus.
The common carotid artery is occasionally tied in the
upper part of this triangle, immediately below the omo-
hyoid muscle, but more frequently the ligature is ap-
plied above the omo-hyoid in the superior carotid
triangle.

(6.) — ^Thb SupiMOR Cabottd TrIAITGHiE.

This triangle is the middle of the three subdivisions
of the anterior triangle of the neck. Its boundaries
are: —

Behind, — Anterior border of sterno-mastoideus.

Above, — Posterior belly of the digastricus.

Below, — Anterior belly of the omo-hyoideus.

The muscles forming the floor are the thyro-
hyoideus, hyo-glossus, and the inferior and
middle constrictors of the pharjmx. Thfe
roof is formed by the same structures as cover
in the inferior carotid triangle.

CoirTEiffTs :

Upper part of lar3mx and lower part of pharynx.

VeiTis. — ^Internal jugular, and those which open
into it, viz. : — Lingual, facial, superior thy-
roid, pharyngeal, and sometimes the occi-
pital.

Arteries. — Termination of common carotid, ex-
ternal carotid, internal carotid, superior
thyroid, lingual, f«JG\«A., ^'a.^cvv^Yc^% ^^ss?y^-

gealf and oocipital. The fiye lasfc-named
are branches of the external oarotid.

Nerves. — Pnenmogastric, superior laryngeal, ex-
ternal laryngeal, hypoglossal, descendens
noni, spinal accessory, and sympathetic.

(c). — The Svb-Mazillabt Triakglb.

This triangle is the most superior of the three sub-
divisions of the anterior triangle, and has the following
boundaries : —

Behind, — Posterior belly of the digastricus.

Above. — Lower border of the body of the jaw, and
line continued from angle of jaw to the maa*
toid process.

In FroKU. — Median line of neck from the chin to
the hyoid bone.*

The muscles forming the floor are the anterior
body of the digastricus, the mylo-hyoideus, and
the hyo-glossus, and its roof is formed by the
same structures as cover in the superior and
inferior carotid triangles.

CoNTEirrs:

Glands. — Portion of parotid and submaxillary
(salivary) glands, submaxillary lymphatic
glands and vessels.

Veins. — Internal jugular, commencement of ex-
ternal jugular (formed by the junction of
the superficial division of the temporo-
maxillary and posterior auricular, and
sometimes of the occipital), radicles of an-
terior jugular, the facial, and those which

* Some anatomists limit this space in front by the anterior
belly of the digastricus. It is, however, better to adhere to the
bonndaries of the original triangle.

open into it below the jaw, viz. : the sub-
mental, sub-maxillary, inferior palatine and
ranine.
Arteries. — External carotid, internal carotid,
facial, sub-mental, mylo-hyoidean, and se-
veral smaller branches.

Nerves, — ^As usually dissected, the superficial
nerves met with in this space are the mylo-
hyoid (branch of inferior dental), and its
branch to the anterior belly of digastric
muscle, the infra-maxillary branches of
facial nerve, and the ascending branches of
the superficial cervical nerve. (The two
latter, strictly speaking, are not contents
of the triangle, as they ramify in the
structures wMch form ite roof.) Deeply
situated at the back part of the space are
the pneumogastric and glossopharyngeal
nerves. That portion of the hypoglossal
nerve, which lies on the hyo-glossus muscle,
should be included as one of the contents.

The stylo-hyoideus, the stylo-glossus, origin of
the stylo-pharyngeus muscles, and stylo-maxillary liga-
ment, may also be given as contents of the space. The
stylo-hyoideus is sometimes given as entering into the
formation of the posterior boundary*

n»— POSTBBIOB TbIAHQLB OF THB NbOX»

The posterior triangle of the neck is the space behind
the posterior border of the stemo-mastoideus, and has
the following boundaries :— >

In Front. — ^Posterior border of stemo-mastoideus.
Behind. — ^Free border of the trapezius.
Below (hose). — Upper border of the middle third
of the clavicle.

Apex, — Meeting of anterior and posterior bound-
aries at the occiput.

Floor {from above downwards), — Splenius capitis,
levator angoli scapulae, scalenus medius,
scalenus posticus and upper digitation of the
serratus magnus.

The space is covered in by the superficial and deep
fascia, and at its lower part by the platysma
myoides.

This triangle is subdivided into two unequal portions
by the posterior belly of the omo-hyoideus. The upper
portion — the larger — is called the occipital triangle^
and has the following contents :

1. Spinal accessory and superficial plexus of cervical

nerves.

2. Transversalis colli artery and vein.

3. Lymphatic vessels and glands (glandulsB con-

catenatse).

The lower portion has been named the subclavian
triangle, and is selected as the best situation for tying
the subclavian artery in the third part of its course.
This triangle has the following contents : —

1. Descending branches of superficial cervical

plexus.

2. Brachial plexus of nerves.

3. Subclavian artery (third part of its course).

4. Transversalis colli artery and vein.

5. Transversalis humeri (supra-scapular) artel*y

and vein.

6. External jugular vein and communicating

branch with cephalic vein.

7. Lymphatic vessels and glands.

III. — ^Thb Sub-Occipital Tbiawglb.

This triacngle is situated immediately under the
occipital bone, and beneath the upper part of the oom-
plexus muscle. Its boundaries are as follows : —

Above. — Obliquus superior.

Below. — Obliquus inferior.

Behind. — Rectus capitis posticus major.

The roof is formed by the complexus muscle, and the
floor by the posterior occipito-atloid ligament and
posterior arch of the atlas.

Contents:

Vertebral artery and sub-occipital nerve (posterior
branch of first cervical,)

rV. — ^Thb Triangle is Fbont op the Elbow-Joint.

BOUITDABIES : —

Externally. — Supinator longfls.

Internally. — Pronator radii teres.

Above (base). — A line — ^imaginary — drawn across
the arm two inches above the condyles.

Apex. — Meeting of the supinator longus and pro-
nator radii teres.

The space is covered in by skin, superficial fascia and.
bicipital fascia, and the floor is formed by the lower
part of the brachialis anticus and the oblique fibres of
the supinator brevis.

CoircEins (From within outwards) : —

1. Median nerve.

2. Brachial artery and vensB comites. About the

centre of the space the artery divides into
radial and ulnar.

3. Tendon of biceps.

4. Museulo-spirsd nerve. (The supinator longns
and brachialis anticus muscles must be slightly
separated in order to expose this nerve).

V. — ScjiKPi^'s Triaxols.
This triangle is situated at the upper part of the
anterior surface of the thigh, immediately below the
fold of the groin, and has the following boundaries : —

ExienmUy. — Sartorius .
IntemaUif, — Adductor longus.
Above (base). — Poupart's ligament.

Apex. — Meeting of the sartorius and adductor
longus muscles.

The space is covered in by skin, superficial feuscia,
ffiuacia lata, and cribriform fascia, and the Jloor is
formed from without inwards by the following
muscles : — ^iliacus, psoas, pcctineus, and small portion
of adductor brevis.

CJONTEHTS: —

1. Femoral sheath derived from the iliac fascia and

fascia transversalis.

2. Femoral artery giving off cutaneous branches

and a lai^ deep branch — ^the profunda
femoris.

3. Femoral vein, here joined by the saphena and

profunda veins.

4. Anterior crural nerve and its branches.

5« Crural branch of genito-crural nerve.

6. Deep lymphatic glands and vessels and fatty
tissue.

VI. — ^Hbsselbach's Triangle.

The space which is known as the triangle of Hessel-
bach is situated at the lower part of the abdominal wall.

on either side, and is of surgical importance, as being
the spot where direct inguinal hernia makes its escape
from the abdomen. Its boundaries are : —

Externally, — Epigastric artery.

Internally, — Outer margin of rectus abdominis
muscle.

Below (base), — Poupart's ligament.

The structures entering into the formation of the
abdominal wall ^ this spot are (from without in-
wards) : —

1. Skin.

2. Superficial fascia.

3. Inter-columnar fascia.

4. Conjoined tendon of internal oblique and trans-

versalis muscles.

5. Fascia transversalis.

6. Sub-serous cellular tissue.

7. Peritoneum.

Note. — ^These seven structures form the coverings of
direct inguinal hernia.

VII.— The Axilla.

The axillary space is of conical form, and is situated
between the upper part of the side of the chest, and the
inner side of the arm, and has the following bound-
aries : —

In Front, — Pectoralis major and minor muscles.

Behind, — Subscapularis, teres major, and latissi-
mus dorsi muscles.

Inner side. — Upper four ribs and intercostal
muscles, and upper part of serratus magnus
muscle.

Outer side, — Upper part of the humerus, the coraco-
brachialis and biceps muscles.

The apex of the cone is directed upwards, and is
formed by an interval between the first rib,
the clayicle, and the upper border of the
scapula ; its hose is formed by the skin and
axillary fascia stretched across from the
lower border of the pectoralis major to the
lower border of the latissimus dorsi.
CoirrENTs:

1. Axillary artery and vein, and their branches.

2. Brachial plexus of nerves, ilid its branches of

distribution below the clavicle.

3. A few branches of the intercostal nerves,

4. About ten or twelve lymphatic glands.

5. A quantity of loose fat and areolar tissue.
Vm. — The TBiAWGirLAB Space at the xtppee paet

OF THE AbM.

When the muscles attached to the head and neck of
the humerus are dissected and cleaned of fat and cellu-
lar tissue, a triangular space exists between the neck
of the humerus and the as^lllary border of the scapula,
which has the following boundaries, as seen from be-
hind : —

Above, — The teres minor muscle.

Below, — ^The teres major muscle.

Outer side, — Head and neck of the humerus.
This space is subdivided into two smaller spaces by
the scapular head of the triceps brachii, one of which
is quadrangular, and the other triangular in form. The
quadrangular is superior, and has the following bound-
aries : —

Above — Teres minor.

Behw, — ^Teres major.

Inner side. — Scapular head of the triceps brachii.

Outer side, — Head and neck of the humerus.

This space transmits the posterior oircumflex vessels
and the circumflex nerve.

The boundaries of the smaller triangular space are :-

Above, — ^Teres minor.

Below, — ^Teres major.

Outer side, — Scapular head of the triceps brachii.
This space transmits the dorsalis scapulee artery and
veins.

IX. — The Poplitbal Space.

The popliteal space is situated at the back of the
knee-joint, and forms what is called the ham. It is
lozenge-shaped, and has the following boundaries : —

Esctemally, — Ahove the joint, biceps flexor cruris ;
helow the joint, outer head of gastrocnemius
and plantaris muscles.

Internally, — Ahove the joint, semi-tendinosus, semi-
membranosus, gracilis and sartorius muscles ;
hehw the joint, inner head of gastrocnemius.

The floor is formed by the lower part of the back of
the femur, the posterior ligament of the knee-joint
(ligamentum postici Winslowii), and the popliteus
muscle covered by its fascia. The space is covered in
by skin, superflcial fascia, and fascia lata.

COKTENTS:

1. Popliteal vessels and their branches.

2. Termination of external saphena vein.

3. Internal and external popliteal nerves and their

branches.

4. Branch of small sciatic nerve.

5. Articular branch of obturator nerve.

6. Four or flve small lymphatic glands.

7. Quantity of fat and loose areolar tissue.

X.— SiKrCTTJBES WHICH LlE ON THE MaSSBT^B

Ml7BCLE.

1. Portion of parotid gland.

2. Glandula socia parotidis.

3. Stenon's duct.

4. Transvorsalis faciei artery and vein.

5. Facial vein.

6. Branches of facial nerve.

XI. — Stbuctubes oisr the Mtlo-Htoid Muscle.

1. Anterior belly of the digastricus.

2. Superficial portion of sub-maxillary gland.

3. Facial vessels with sub-maxillary and sub-

mental branches.

4. Mylo - hyoidean artery (branch of inferior

dental from 1st division of the internal
maxillary).

5. Mylo-hyoidean nerve (branch of inferior den-

tal from third division of the fifth nerve).

Xn. SlBTTCTirBBS BeNEATH THE MtLO-HyOID-

MlJSCLE.

1. Sub-lingual gland.

2. Deep part of sub-maxillary gland.

3. Wharton's duct.

4. Sub-lingual artery.

6. Ranine artery.

6. Gustatory nerve (from third division of the

fifth nerve).

7. H3rpoglossal nerve.

8. Sub-maxillary ganglion.

9. Genio-hyoideus

10. Genio-hyo-glossTis I ^^

11. Hyo-glossus

12. Stylo-glossus

XIII. — Strtjctuees on the Hto-Glossus Mttscle.

1. Deep part of sub-maxiUary gland.

2. Wharton's dnct.

3. Gustatory nerve.

4. Hypo-glossal nerve.

5. Sub-maxiUary ganglion.

6. Digastricus

7. Stylo-hyoidens

8. Siylo-glossns

9. Mylo-hyoideus

mnscles.

XIV. — SiBTroTinEUss Beneath the Hyg-Glossus

Muscle.

1. Lingual artery and veins with dorsal branches.

2. Glosso-pharyngeal nerve.

3. Stylo-hyoid ligament.

4. Genio-hyo-glossus

5. Superficial linguaHs

6. Middle constrictor

muscles.

Note. — All the structures going to the tongue pass
either under or over the hyo-glossus muscle.

XV.— Stbttctttees Bbhtoath the Steeno-Cleido-

Mastoidetts.

1. Deep layer of cervical fascia.

2. Stemo-clavioular articulation with its ligaments.

3. Sternal portion of stemo-thyroideus.

4. „ „ „ sterno-hyoideus.
6. Central portion of omo-hyoideus.

6. Portions of scalene muscles.

7. „ of splenius capitis and splenius colli*

8. Origin of posterior belly of the igastricus.

9. Portion of levator anguli scapulsB.
10. Common carotid artery in its sheath

11. Commencement of external carotid artery with

its posterior branches.

12. Commencement of the internal carotid artery.

13. Transversalis coUi artery and vein.

14. Transversalis humeri (suprascapular) artery

and vein.

15. Internal jugular vein (in carotid sheath).

16. Deep cervical (lymphatic) glands.

17. Portion of parotid gland.

18. Cervical plexus of nerves.

19. Hypoglossal (ninth) nerva

20. Descendens noni nerve.

21. Pneumogastric nerve (in carotid sheath).

22. Spinal accessory nerve.

23. Phrenic nerve.

24. Facial nerve.

25. Sympathetic nerve.

XYI. — SiBuorrBEs Beitsath the Deltoid Muscle.

1. A large bursa.

2. Head and neck of humerus.

3. Coracoid process of scapula.

4. Capsular ligament.

5. Coraco-acromial ligament.

6. Coraco-humeral ligament.

7. Coraco - clavicular ligaments (trapezoid and

conoid).

8. Costo-<;oracoid ligament and membrane (exter-

nal attachments).

9. Tendon of pectoralis minor.

10. Both heads of biceps.

11. Origin of ooraco-brachialis.

12. Tendon of sub-scapularis.

13. „ „ pectoralis major.
14. „ „ supra-spinatus.

15. Tendon of infranspinatus.

16. „ „ teres minor.

17. ,, „ teres major.

18. „ „ latissimns dorsi.

19* Scapular and external heads of triceps.

20. Anterior and posterior circumflex arteries and

veins.

21. Acromio-thoraoic artery and vein.

22. Branch of superior profunda artery and veins.

23. Circumflex nerve (from posterior cord of

brachial plexus).

XVII. — Strtjctubbs Beneath the Gluteus Maximus

Muscle.

1. Fart of gluteus medius.

2. Lowet border of gluteus minimus (in some

subjects).

3. Supeiicial branch of gluteal artery.

4. Pyriformis muscle.

5. Sciatic vessels.

6. Sciatic nerves (great and small.)

7. Pudic vessels and nerve.

8. Nerve to obturator intemus.

9. Gemellus superior.

10. Tendon of obturator intemus.

11. Gemellus inferior.

12. Quadratus fcmoris.

13. Great trochanter of femur.

14. Tuber ischii.

15. Origin of semi-membranosus.

16. „ „ semi-tendinosus.

17. „ „ biceps.

18. Upper part of adductor magnus.

19. Three bursse, viz., one over trochanter major,

one over the tuberosity of the ischium, and
one over the vastus exteTrL\\ft.

20. Great sa^'.ro-ischiatic ligament.

NoTB. — ^The tendon of the obturator extemuB cannot
be seen until after reflecting the quadratus femoiiB.

XVlII. — Stbitotubes Passing thboitgh ths Supbbiob

Apebtube of Thobax.

K muscles.

1. Bight and left stemo-hyoideus

2. „ „ „ stemo-thyroideus

3. „ „ „ longus colli

4. Trachea.

5. (Esophagus.

6. Thoracic duct (on left side.)

7. Superficial lymphatic vessels of liver, and

lymphatic vessels of right side of chest.

8. Innominate artery (right side.)

9. Left common carotid artery.

10. Left subclavian artery.

11. Right and left internal mammary arteries.

12. „ if „ superior intercostal arteries.

13. Thyroidea ima artery (if present.)

14. Eight and left innominate veins.

15. „ „ „ inferior thyroid veins.

16. „ „ „ phrenic nerves.

17. „ „ n pneumogastric nerves with car-
diac branches.

18. Left recurrent laryngeal nerve.

19. Bight and left sympathetic nerves with cardiac

branches.

20. Bight and left first dorsal nerves.

21. Bemains of thymus gland.

22. Apices of lungs and pleurae.

23. Deep cervical fascia passing on to pericardium.

XIX. — The MEniASTDnrM.
The mediastinum is the space in the middle line of

the thorax, formed by the approximatioii of the pleura
on either side, and extends from the sternum in front,
to the bodies of the vertebrse behind. In no place do
the reflected pleurse come in contact with each other,
so that the space between them forms a complete sep-
tum, dividing the two pulmonary cavities. The media-
stinum is divided into three portions; (o), anterior
mediastinum; (6), middle mediastinum ; (c), posterior
mediastinum, which contain all the viscera of the
chest, with the exception of the lungs. The boundaries
and contents of the three divisions are as follows : —

(a.) — AirrBBioB MBDiASTnnoc.

BoirND ABIES :

In Front — ^The sternum.
Behind — Pericardium.
Laterally — Pleurae.

Contents:

1. Origin of sterno-hyoideus muscles.

2. „ „ sterno-thyroideus muscles.

3. Triangularis stemi muscle.

4. Left internal mammary artery and venee

comites.

5. Remains of th3rmus gland.

6. Loose areolar tissue.

7. Lymphatic vessels from convex surface of

liver.

I^OTE. — The right internal mammary vessels being
covered by pleura, is not included among the contents
of the space.

(6.)— Middle Mediastinxtm.

BoxmDABiEs :

In Front, — Anterior mediastinum.
Behind^ — Posterior mediastinum.
Laterally, — Pleuree.

COHTEHTS:

1. The heart enclosed in pencardium.

2. Ascending portion of aorta.

3. Superior vena cava.

4. Bifurcation of trachea.

5. Puhnonary artery and veins.

6. Phrenic nerves (from third, fourth, and fifth

cervicaL)

7. Arteriae comites nervi phrenid (from internal

mammary.)

(c.) — Posterior MEDiAsmnnc.

BOUKDARIES :

In Front. — Pericardium and root of lungs.
Behind. — Vertebral column.
Laterally. — PleurfiB.

COSTENXS :

1. Descending aorta.

2. Yena azygos major.

3. Vena azygos minor.

4. Superior intercostal veins.
6. Pneumogastric nerves.

6. Great splanchnic nerves.

7. (Esophagus.

8. Thoracic duct.

9. Lymphatic glands and vessels.

XX. — Structures Constituting Root of Lung.

1. Bronchus.

2. Pulmonary artery.

3. Pulmonary veins.

4. Bronchial vessels.
/). Bronchial glands.

0. Anterior and posterior pulmonary ploxuHes of

iior\'C8.
7. <V))iii(M.'tivo tissue.

The following are the relations of the pulmonary
veins, pulmonary artery and bronchus on eitlier side :

Bight Side, — From before, backwards; veins,
artery, bronchus. From above, downwards ;
bronchus, artery, veins.

Left Side. — From before, backwards; same as
right side. From above, downwards ; artery,
bronchus, veins.

XXI. — Stkxjctures is Concavity of, anb Bshiki),

Arch of Aorta.
In Concavity :

1. Biforcation of pulmonary artery.

2. llemains of ductus arteriosus.

3. Left bronchus.

4. Left auricle.

5. Left recurrent laryngeal nerve.

6. Cardiac plexus of nerves.

7. Numerous lymphatic glands.

Passing Behind:

1. (Esophagus.

2. Thoracic duct.

3. Traphea.

4. Left recurrent laryngeal nerve.

5. Right pulmonary artery.

XXII. — Structures between the Clavicle akd

First Rib.

1, Rhomboid ligament.

2. Subclavius muscle.
, 3. Lymphatic vessels.

4. Subclavian artery.

•5. Subclavian vein.

n. External cord of l)rarlnMl ^iloxus of ncrvos,

7. InkTiial cord of ..

8. Posterior thoracic nerve, or external respiratory

of BeU.

9. External anterior thoracic nerve (occasionally).

XXIII. — ^Thb Costo-Coracoid Mbmbbawb.

The costo-coracoid membrane is a sheath of fascia
derived from and continuous with the deep layer of
cervical fascia, which encloses the axillary vessels for
a short distance at their upper part, and corresponds'
to the femoral sheath in the lower limb. Externally
it is attached to the coracoid process of the scapula, and
internally to the lower border of the clavicle, as far as
the inner extremity of the first rib. Above, it is con-
tinuous with the deep layer of cervical fascia, which
forms the sheath of the subclavius muscle. The mem-
brane is pierced by the following structures : —

1. Acromio-thoracic artery.

2. Superior thoracic artery.

3. Cephalic vein.

4. External anterior thoracic nerve.

XXIV. — Kelations of the Trachea m the Neok.

Anteriorly :

1. Skin and superficial fascia.

2. Layers of deep fascia.

3. Anterior jugular veins.

4. Inferior thyroid plexus of veins.

5. Left innominate vein.

6. Thyroidea ima artery (in some subjects).

7. Isthmus of thyroid body.

Posteriorly :

1. (Esophagus.

2. Inferior or recurrent laryngeal nerves.

3. Vertebral column.

Laterally :

1. Lobes of thjrroid body.

2. Carotid arteries.

3. Inferior thyroid arteries.

XXV.— Eelations of the Peostatb Gland.

Above. — Bladder, anterior true ligaments of
bladder and dorsal vein of penis.

In Front. — Symphysis pubis, triangular ligament
and sub-pubic ligament.

Behind, — Eectum (at bend between second and
third parts).

Behind and Above. — Recto-vesical pouch of peri-
toneum.

Behind and Behw. — Third part of rectum,
vesiculse seminales and vasa deferentia.

Below. — Central point of perineum and perineal
raph^.

Behw and in Front, — ^Triangular ligament, mem-
branous urethra, and bulb of urethra.

Laterally, — Anterior fibres of levator ani muscle,
recto-vesical fascia, and prostatic plexus of
veins.

XXVI. — Stbuctxtees Passing Thbough Inlet of

Pelvis.

(a). ^VlSCEBA AND DuCTS.

1. Rectum.

2. Small intestines (generally).

3. Ureters.

4. Vasa deferentia (in male subjects), round liga-

ment (in female subjects).

5. Urachus and obliterated hypogastric arteries.

6. Bladder (if distended).

7. Uterus (in female, if pregnant).

(6). — Vessels.

1. Internal iliac.

2. Superior haemorrhoidal.

3. Branches of vasa intestini tenuis.

4. Sacra media.

5. Hio-lumbar.

6. Ovarian (in female subjects).

7. Obturator (if from deep epigastric).

8. Pubic branches from external epigastric

arteries.

9. Numerous lymphatic vessels.

(c.) — Nerves.

1. Lumbo-sacral cord.

2. Obturator.

3. Sympathetic.

' 4. Branches from h3rpogastric plexus.

In addition to the above, the peritoneum investing
the various viscera and the fascise from the abdominal
parietes, which become pelvic, should be enumerated
among the structures passing through the inlet of the
pelvis.

XXVII. — Viscera Covered or Invested by Peritoneum.
(a J — almost entirely invested.
Liver Transverse colon

Stomach Sigmoid flexure of colon

Spleen First part of rectum

First part of duodenum Uterus and ovaries (in
Jejunum female)

Ileum

(b,) — PARTIALLY INVESTED.

Second and third parts

of duodenum
Caecum

Ascending colon
Descending colon

Middle part of rectum
Posterior surface of bladder
Upper part of posterior
wall of vagina (in female)

(e), OOYBBED BUT NOT IirYBSTBD.

Kidneys
Snpranrenal capsules

Pancreas

XXVin. — Contents op Spinal Canal.

The following structures are included in the content's
of the spinal canal, about its middle, and are met with
in the order given, from without inwards.

1. Venous plexus — meningeo-rachidian veins —

between the bone and dura mater, and sur-
rounded by loose fat.

2. Dura mater.

3. Arachnoid membrane, parietal and visceral

layers, the former merely epithelial. Between
the two layers is the arachnoid space,

4. Pia mater, with linea splendens in median line,

and ligamentwm, denticulattmi between the
anterior and posterior roots of spinal nerves.
Between the arachnoid and pia mater is the
suh-arachnoid space, and a variable amount of
serous fluid.

5. Spinal arteries (one anterior and two posterior)

with their accompanying veins ramifying in
pia mater.

6. Spinal cord with anterior and posterior roots

of nerves.
Vote. — In addition to the above, the canal contains the
spinal accessory nerve in the cervical region, and the
eattda equina below the first lumbar vertebra.

XXIX. — ^The Soft Palate.

The sofb palate is the name given to the fold of
mucous membrane, situate at the posterior part of the
mouth and continuous with the roof or hard palate.
Fron^ the middle of its iQferior border depends the

uvula, and passing outwards from the uvula, on each
side are two curved folds of mucous membrane, the
arches, oipiVara of the palate. The two pillars are
closely united above, but below they are separated by a
triangular interval which lodges the tonsil. The anterior
pillar terminates at the side of the base of the tongue,
and is formed by the prominence of the palato-glossus
muscle. The posterior pillar ejA^iiiA& downwards and
backwards into the pharynx, and is formed by the con-
vexity of the palato-pharyngeus muscle. Between the
soft palate and the root of the tongue is the opening
from the mouth into the pharynx. This space is known
afi the isthmus of the fauces. Its boundaries are : —

Above. — Soft palate.

Below, — Root of tongue.

Laterally. —Pillars of the palate and tonsils.

In dissecting the soft palate from behind forward
the following structures are met with : —

1. Mucous membrane.

2. Submucous tissue, glands, vessels, &c.

3. Falato-phar3aigeus muscle, posterior fasciculi.

4. Levator palati and azygos uvuIsb muscles.

5. Palato-pharyngeus, anterior fasciculi.

6. Aponeurosis of tensor palati muscle.

7. Palato-glossus muscle.

8. Submucous tissue, glands, vessels, &c.

9. Mucous membrane.

XXX.— Structueb op the Eyelids.

The eyelids are composed of the following structures,
in the order given from without inwards :—

1. Skin.

2. Orbicularis palpebrarum muscle. '
8. Palpebral ligament.

4. Tendon of levator palpebrsB (upper lid only)

5. Tarsal cartilage.

6. Meibomian glands,

7. Conjunctiva.

XXXI. — The iNauiNAL Canai akd Covebinos of

Ingtiinal Hebnia.

The inguinal or spermatic canal commences at the
internal abdominal ring, and terminates at the external
abdominal ring, its length being about one and a half
inches. It serves for passage of the spermatic card in
the male, and the round ligament with its vessels in the
female. Its boundaries are : —

In front. — Tendon of external oblique muscle,
lower border of internal oblique and small
portion of cremaster muscle.

Behind. — Fascia transversalis ; conjoined tendon of
internal oblique and transversalis muscles,
and the triangular fascia.

Above, — Arched border of transversalis muscle.

Below. — Pouparfs ligament.

The inguinal canal is of great surgical importance
on account of its being the channel through which
inguinal hernia escapes from the abdomen. Inguinal
hernise are of two kinds, oblique and direct. The former
enters the inguinal canal through the internal abdo-
minal ring, passes obliquely along the canal and through
the external ring to descend into the scrotum. Direct
inguinal hernia escapes from the abdomen at Hessel-
bach's triangle, (vide Aid YI.) and passes through the
external ring.

The following are the coverings of each variety of
hernia commencing at the surface :-*

Ji2

Oblique.

1. Skin.

2. Superficial fascia.

3. Intercolnmnar fascia.

4. Oremaster mnscle.

5. Fascia transversalis, or in-

fnndibnliform fascia.

6. Sub-serous cellular tissue.

7. Peritoneal sac.

Direct.

1. Skin.

2. Superficial fascia.

3. Intercolnmnar fascia.

4. Conjoined tendon of internal

oblique and transversalis
muscles.

5. Fascia transversalis.

6. Sub-serous cellular tissue.

7. Peritoneal sac.

XXXII. — The Spermatic Cord.

The spermatic cord commences at the internal ab-
dominal ring, passes obliquely along the ingninal canal,
escapes at the external abdominal ring, descends into
the scrotum and terminates at the posterior border of
the testicle. The structures entering into the compo-
sition of the cord are : —

1. The investing tunics, or coverings of the cord,

viz., (a) external spermatic or intercolnmnar
fascia; (b) oremaster muscle; (c) internal
spermatic fascia or fascia propria.

2. The vas deferens. The vas deferens has three

coats (a) external or fibrous coat ; (b) middle
or muscular coat; (c) internal or mucous
coat lined with squamous epithelium.

3. Spermatic artery (from abdominal aorta).

4. Deferential artery (from superior vesical)*

6. Cremasteric artery (from epigastric).

6* Yena spermatica (the smaller veins are called
vasa pampiniformia on account of their
peculiar tendril-like arrangement).

7. Lymphatic vessels (numerous and of large size)^

8. Spermatic plexus of nerves (from the aortic

and renal plexuses of the sympathetic).
0. Genital branch of the genito-crural nerve*
10. Scrotal branch of the ilio*inguinal nerve.

XXXin. The Critral Canal and Coverings op

Femoral Hernia.

The crural or femoral canal is a funnel-shaped in-
terval which exists within the femoral sheath between
its inner wall and the femoral vein, and is of great
surgical importance as being the space into which the sac
of femoral hernia is protruded. It is limited above by the
crural or femoral ring and is lost below by the adhesion
of the sheath to the coats of the vessels. In the normal
state the canal is occupied by loose cellular tissue, and
numerous IjnDoiphatic vessels which perforate the cribri-
form fascia covering the saphenous opening in the fascia
lata and the walls of the sheath to reach a lymphatic
gland situated at the crural ring. This gland is retained
in its position by a thin layer of sub-serous cellular
tissue — 8q)ttim crurale — which, together with the
peritoneum, separates the canal from the abdominal
cavity. • The crural ring is the point where femoral
hernia leaves the abdomen and is the most frequent
seat of strangulation ; its boundaries are : —

In front — Poupart's ligament.

Behind, — Ilio-pectineal line and body of os pubis.

Externally. — Femoral vein.

IntemaUy, — ^The sharp margin of Gimbernat's
ligament.

The coverings of femoral hernia commencing at the
surface are :—

1. Skin.

2. Superficial fascia.

3. Cribriform fascia.

4. Femoral sheath or fascia propria^
5k Septum crurale.

6. Peritoneal sac.

XXXIV.— The Pakotid Gland.

The parotid — the largest of the salivary glands — ^is
situated in front of and below the extem^d ear, and
extends forwards on the masseter muscle on which also
lies a smaU, more or less detached, portion called the
soda parotidis. It is bounded above by the zygoma,
below by an imaginary line drawn from the angle of
the jaw to the sterno-mastoid muscle, and behind by
the meatus auditorius extemus, the mastoid process of
the temporal bone, the stemo-mastoideus and posterior
belly of the digastricus. It extends deeply into the neck
by means of two processes. One dips behind the
styloid process, and projects beneath the mastoid process
and the sterno-mastoid muscle. The other process
passes in front of the styloid process to the back of the
glenoid fossa, behind the articulation of the lower jaw.
Embedded in the gland is the external carotid artery,
with its posterior auricular, temporal and internal
maxillary branches. The transverse facial (a branch of
the temporal) emerges from it in front. Superficial to
the external carotid artery, the temporal and internal
maxillary veins join to form the external jugular, from
which a branch passes through the gland forming a
communication with the internal jugular vein, which
with the internal carotid artery, lies close to its deep
surface. It is traversed by the facial nerve and its
branches, and by branches of the great auricular nerve,
which(here communicate with the facial. Its duct (Steno's)
commences at the anterior border of the gland by the
junction of numerous branches, and, crossing the
masseter muscle, is joined by the duct from the socia
parotidis. At the anterior border of the muscle, the
duct dips inwards, pierces the buccinator muscle and
mucous membrane, opening into the mouth opposite the
second molar tooth of the upper jaw. The duct con*

sists of two ooats, an external or fibrous coat, and an
internal or mucous coat lined with columnar epithelium.
The gland receives its blood supply from the vessels
embedded in it above enumerated, and its nerve supply
from the carotid plexus of the sympathetic, the auriculo-
temporal, and great auricular nerves.

On cutting into the substance of the parotid gland
the structures met with in order from the surface are
as follows : —

1. Two or more small absorbent glands.

2. " Pes anserinus," or primary branches of the

facial nerve.

3. Branches from the auriculo-temporal nerve

which here communicate with the facial
nerve.

4. The external jugular vein formed by the

junction of the internal maxillary and
temporal veins.

5. The external carotid artery which, after giving

off several branches in the gland, divides
opposite the neck of the jaw into internal
maxillary and temporal.

XXXV. — ^Thb Ckanial Nerves.

According to the arrangement of "Willis, which is
usually adopted in England, there are nine pairs of
cranial nerves, numbered according to the openings in
the base of the cranium. He also included the sub-
occipital nerve among the cranial nerves forming a
tenth pair; this is now reckoned among the spinal
nerves, forming the first cervical. On the Continent,
the arrangement of Willis is not recognised, that of
Soemmering being universally employed. In his system
the facial and auditory nerves (7th) are reckoned as

separate pairs, as are also the glosso-pharyngeal,
pneumogastric and spinal accessory, wluch together
form the 8th. pair of Willis's. Thus the nine pairs of
Willis's equal the twelve pairs of Soemmering's, system
as will he seen from the following table : —

SOEMMEBINO.

1. Olfactory.

2. Optic,

3. Motores ocnlorum.

4. Pathetici.

5. Trifacial.

6. Abdncentes.

7. Facial (portio dura.)

8. Auditory (portio mollis.)

9. Glosso-pharyngeal.

10. Pneumogastric (vagus or
par vagum.)

11. Spinal accessory.

12. Hypoglossal.

These nerves may be classified according to their
physiological functions into three groups as follows : —

Nerves of Special Sense, — Olfactory, (1st.) ; Optic,
(2nd.) ; and Auditory, (portio mollis of 7th.)

Nerves of Motion, — Motores oculorum, (3rd.) ;
Pathetici, (4th.); Abducentes, (6th.); Facial, (portio dura
of 7th.) ; and Hypoglossal, (9th.)

Compound Nerves: Motor and Sensory, — ^Trifacial
(5th.); Glosso-pharyngeal, Pneumogastric and Spinal
accessory, (8th.)

WlLUS.

1. Olfactory.

2. Optic.

3. Motores oculorum.

4. Pathetici (or trochleares.)

5. Trifacial (or trigemini.)

6. Abducentes.

7. Facial and auditory.

8. Glosso-pharyngeal, pneumo-

gastric and spinid acces-
sory.

9. Hypoglossal

XXXVI. — The Olpactoey Nbbve.

Origin, — By three roots, an inner or short root^
middle root, and external or long root. The fibres of
the inner root arise from the inner and posterior part
of the anterior lobe, close to the substantia perforata ;
the grey fibres of the middle root spring from the

oarancula mamillaxis, and the white from the corpus
striatum ; the fibres of the external root may be traced
into the middle lobe of the cerebrum, being continuous
with the fibres of the anterior commissure and the
exterior white substance of the thalamus opticus.

Course. — The three roots having united, pass forward
on the under surface of each anterior lobe of the
cerebrum between the pia mater and arachnoid and rest
on the cribriform plate of the ethmoid bono. Towards
its extremity the nerve increases in size, forming an
oblong mass of grey and white matter which is called the
IvXbus olfadorius,

Bistribution, — ^The branches of distribution are given
off from the under surface of the hulhus olfactorius, and
pass through the foramina in the cribriform plate of
the ethmoid bone in three groups to supply the mucous
membrane of the nares. The nerves forming the inner
of the three groups are spread out upon the septum
narium, those of the middle group supply the mucous
membrane of the roof of the nasal fossse, and the outer
group are distributed on the superior and middle
turbinated bones.

XXXVn. — The Optic Nerve.

Ort^n.— Prom the corpora geniculata, the thalamus
opticus and from the nates.

Course. — From the above origin it winds around the
cms cerebri as a flattened band called the tractus opticus,
and unites with its follow of the opposite side in front
of the tuber cinereum, to form the optic commissure.
The tractus opticus is united with the cms cerebri, and
the tuber cinereum. The commissure is also united
with the tuber cinereum from which it receives some
fibres. Beyond the commissure, the nerve diverges from

its fellow, becomes rounded in form, and is enclosed in
a sheath derived from the arachnoid. It then passes
forward through the optic foramen to enter the orbit.
At the optic foramen the nerve receives a sheath from
the dura mater, which at this point splits into two
layers, one of which becomes the periosteum of the
orbit ; the other, as above stated, encloses the nerve up
to the point where it pierces the eyeball, when the
sheath becomes continuous with the sclerotic coat.
After a short course within the orbit, the optic nerve
pierces the sclerotic and choroid coats of the eyeball.

Distribution, — As soon as the nerve has pierced the
eyeball it spreads out on its internal surface forming
the retina.

Note. — Within the commissure the innermost fibres
of the optic nerves cross each other to pass to opposite
eyes, the outer fibres continue their course uninterrupted
to the eye of the corresponding side; some fibres pass
in an arched direction, from one nerve to the other
behind, and others taking a similar course in front,
connect the two retinae. ("Wilson.)

XXX Yin. — The Third Paib op Nerves.

Origin. — ^The superficial origin of this nerve is from
the inner side of the cms cerebri close to the pons
Varolii, but its fibres may be traced into the grey
substance of the crus, into the longitudinal fibres of
the pons (the motor tract), into the corpora quadri-
gemina and valves of Vieussens, and to a grey nucleus
in the floor of the aqueduct of Sylvius.

Course.— From the inner side of the crus cerebri
the nerve passes forward between the posterior cerebral
and superior cerebellar artery, and pierces the dura

mater inunediately in front of the posterior cluioid
process. It then descends obliquely into the external
wall of the cavernous sinus and divides into two
branches which enter the orbit through the sphenoidal
fissure and between the two heads of origin of the
external rectus muscle.

Distribution, — The swperior of its two branches
ascends and supplies the superior rectus and levator
palpebraB. The inferior divides into three other
branches, one of which passes beneath the optic nerve
to the internal rectus, another passes to the inferior
rectus, and the third, a long branch, supplies the
inferior oblique. From this branch a short thick
branch is given to the ophthalmic or lenticular
ganglion.

Note. — ^The branches of this nerve enter the muscles
they supply on their ocular surface. In paralysis of
this nerve there is dropping of the eyelid (ptosis),
external strabismus and dilatation of the pupil.

XXXIX,— The Foueth Pair.

Origin, — ^The sv{perficial origin of this nerve is from
the valve of Vieussens close to the testis. Its deep
origin may be traced in two fasciculi, to a grey nucleus
in the floor of the aqueduct of Sylvius in front, and to
a similar nucleus in the floor of the fourth ventricle
behind. The fibres of origin of the two nerves
communicate with each other, forming a kind of
commissure.

Course. — The nerve first winds round the cms
cerebri to the extremity of the petrous portion of the
temporal bone, when it pierces the dura mater below
the third nerve, and passes forward in the outer wall

of the cavernous sinus to the sphenoidal fissure through
which it passes to the orbit. Having entered the orbit,
it crosses the levator palpebree muscle near its origin
to reach the orbital surface of the superior oblique
muscle.

Distribution. — ^This nerve is specially distributed to the
superior oblique or trochlearis muscle; hence it is often
termed the trochlear nerve. While in the cavernous
sinus, the fourth nerve sends a branch of commxmicar
tion to the ophthalmic nerve, and gives off a recurrent
branch, consisting of sympathetic filaments derived from
the carotid plexus which is distributed to the lining
membrane of the cavernous sinus.

Note. — Sometimes the recurrent nerve is a branch
of the ophthalmic nerve, and occasionally it arises
direct from the carotid plexus.

XL. — The Fifth Path of Nerves.

Origin. — ^Like the spinal nerves, the fifth nerve
arises by two roots, a motor and a sensory. The nerve
makes its appearance on the surface of the brain—
superjicial origin — at the side of the pons Varolii;
Here it consists of two fasciculi, separated by a narrow
interspace. The smaller, or anterior, is the motor root ;
and the larger, or posterior, the sensory. The former
consists of about twenty nerve filaments, and the latter
of from seventy to a hundred. The fibres of the pos-
terior root can be traced between the transverse layers
of the pons Varolii behind the corpus olivare, and be-
tween the corpus restiforme and fasciculus innomina-
tus (teres) to its deep origin in the grey substance of
the floor of the fourth ventricle. The fibres of the

anterior root can be traced to the longitudinal fibres
which are prolonged upwards from the corpus pyra-
^^midale; but, according to Stilling, the anterior root
also has its dt&p origin from the grej substance of the
fourth -ventricle.

Cowrse. — From the side of the pons Varolii the two
roots pass forward and through an oval opening in the
tentorium cerebelli, near the apex of the petrous por^
tioB of the temporal bone. Here the posterior root
spreads out into a large semilunar ganglion, the
Gasserian, which is lodged in a depression in the bone.
The anterior root is not connected with the ganglion,
but passes beneath it and through the foramen ovale,
when it unites with the inferior maxillary nerve.
From the anterior or convex border of the ganglion
are given off three large trunks : —

(a) The ophthalmic nerve, which passes forward in
the outer wall of the cavernous sinus, and enters the
orbit through the sphenoidal fissure, (h) The superior
maxillary nerve, which passes forward through the
foramen rotundum to enter the spheno-maxillary fossa,
(c) The inferior maxillary nerve, which is given off
from the inferior angle of the ganglion, and makes its
exit from the cranium almost immediately, through the
foramen ovale.

The further course and distribution of the three
divisions of the fifth nerve will be considered under
their respective headings.

Note.— The Gasserian ganglion receives some fila-
ments from the carotid plexus of the sympathetic, and
gives off a few small branches to supply the tentorium
cerebelli and the dura mater in the middle fossa of the
ctanium.

(a). — TffB Ophthalmic Nerve.

The ophthabnic nerve arises from the upper part of
the Gasserian ganglion by a short trunk, about three
quarters of an inch in length, and passes forward in
the outer wall of the cavernous sinus, Ijdng externally
to the other nerves. After receiving several filaments
from the carotid plexus of the sympathetic, it divides
into three branches — tachryrrud, frontal, and nasal.
Before its division it gives off a small recwrrent branch,
which passes backwards with the recurrent branch of
the fourth nerve, between the layers of the tentorium
cerebelli, to the lining membrane of the lateral sinus.

The lachrymal Nerve is the smallest of the three
branches of the ophthalmic. It enters the orbit
through the narrowest part of the sphenoidal fissure,
external to the frontal nerve, and passes forward above
the upper border of the external rectus muscle, in
company with the lachrymal artery, to the lachrymal
gland, where it divides into two branches, superior and
inferior. The sv/perior branch supplies the upper sur-
face of the gland, and is continued forwards through a
foramen in the malar bone to communicate with the
Bubcutaneus malsB (br. of sup. maxillary nerve), and a
filament of the facial nerve. The inferior branch sup-
plies the under surface of the gland, the upper eyelid,
and the outer angle of the eye. In the orbit the
lachrymal nerve has a connecting filament with the
orbital branch of the superior maxillary nerve. Some^
times it receives a branch from the fourth nerve. When
this occurs, the lachrymal appears to arise by two
roots*

The Frontal Nerve^ the largest branch of the ophthal-
mic, enters the orbit immediately to the outer side of
the fourth nerve, and passes forward along the middle
line of the orbit between the levator palpebrse muscle

and the periosteam. About midway between the apex
and base of the orbit it divides into two branches, the
Bupra-orbital and the supra-trochlear. The mpror-
orbital branch is the proper continuation of the nerve.
It passes out of the orbit through the supra-orbital
not'Ch, in company with the supra-orbital artery, gives
off filaments to supply the upper eyelid, the pericranium,
and muscles of the forehead, viz., — corrugator super-
cilii, occipito-firontalis, and orbicularis palpebrarum, and
divides into two cutaneous branches, internal and ex*
temal, which supply the skin in front of the head as
far as the summit, and around the side as far back as
the occiput.

The Nasal Nerve enters the orbit between the two
heads of the external rectus muscle, and between the
two branches of the third nerve. It crosses the optic
nerve obliquely, in company with the ophthalmic artery,
beneath the levator palpebrsB and superior rectus
muscle, to reach the inner wall of the orbit where it
enters the anterior ethmoidal foramen, passing through
which it re-enters the cavity of the cranium. It then
traverses a shallow groove on the front of the cribri-
form plate of the ethmoid bone, passes down through
the slit-like opening by the side of the crista galli into
the nose, where it divides into two branches, internal
and external. The internal branch supplies the
mucous membrane near the fore part of the septum
of the nose; the external^ after giving off a few filar-
ments to the mucous membrane of the nares, passes
outwards between the nasal bone and cartilage to
supply the skin of the ala and tip of the nose.

Whilst in the orbit the nasal nerve gives off the
followiog branches :

1. — Ganglionic : a slender nerve, half an inch in
length, which enters the upper angle of the

ophthalmic ganglion and constitnteB its su-
perior or long root.

2. — Ct7iary {Long ciliary nerves) : Two or three long
slender filaments which pierce the sclerotic
coat near the short ciliary nerves, and passing
through the globe of the eye between the
sclerotic and choroid coats, are distributed to
the ciliary muscle and iris.

3. — Infra-4roMear I a small branch which is
given off just as the nasal nerve enters the
anterior ethmoidal foramen, and passes for-
ward along the upper border of the internal
rectus muscle to the inner angle of the eye,
where it communicates with the supra-
trochlear (br. of frontal) nerve, and is dis-
tributed to the lachrymal sac, orbicularis
palpebrarum, conjunctiva, skin of the eyeUds
and side of the nose.

KoTB. — The first division of the 5th nerve is entirely
sensory in fanction. It supplies branches to the eye-
ball ; ophthalmic ganglion ; lacluymal gland ; mucous
membrane of the nose and eyelids ; skin of the nose,
eyelids, forehead, upper part and sides of the hairy
scalp ; muscles above the middle of the circumference
of the orbit, the pericranium, &c.

(b) The Supbbiob Maxillaby Nebve.

This nerve arises from the middle of the Gasserian
ganglion, passes horizontally forward, and makes its
exit from the skull through the foramen rotundum in
the sphenoid bone. It then crosses the spheno-maxillary
fossa and enters the canal in the fioor of the orbit,
which it traverses, and emerges on the face at the

in£ra-orbitaI foramen beneath the levator labii super-
ioris mnscle. Here it divides into a number of
branches which, together with branches of the facial
nerve, form a plexus — ^the infra-orbital plexus.

The branches of distribution of this nerve are divided
into three groups : those given off in the spheno-
maxillary fossa, those given off in the infra-orbital
canal, and those given off on the face (terminal
branches), thus : —

Spheno-maxiUary fossa

'Infra-orbital canal

' Orbital or temporo-malar.
Spheno-palatine.
Posterior dental.

Palpebral.
On the face -l Nasal.

r Middle dental.
\ Anterior dental.

or muscular

and
cutaneous.

Labial.

The Orbital or temporo-malar branch enters the orbit
through the spheno-maxillary fissure and divides into
two branches, temporal and malar. The temporal branch
ascends along the outer wall of the orbit, receives a
branch from the lachrymal nerve, passes through a
foramen in the malar bone, and enters the temporal
fossa, where it communicates with the deep temporal
nerves (brs. of inferior maxillary). It then pierces the
temporal muscle and temporal fascia, and supplies the
skin of the temple and side of the forehead communi-
cating with the facial and anterior temporal nerves.
The malar branch passes along the inferior angle of the
outer wall of the orbit, emerges on the face through a
foramen in the malar bone, and pierces the fibres of
the orbicularis palpebrarum muscle, to reach the skin
of that region. This nerve is sometimes called subeu-

taneus malsB. It communicates with branches of the
infra-orbital, facial and lachrymal nerves.

The Spheno-palatine are two branches which pass
downwards to the spheno-palatine or Meckel's gangHon.

The Posterior dental are two branches which arise
from the tmnk of the nerve just as it is about to enter
the infra - orbital canal, and pass downwards upon
the tuberosity of the superior maxillary bone. One of
the branches passes forward through the substance of
the bone, giving off numerous filaments which supply
the molar and bicuspid teeth, the lining membrane of
the antrum and corresponding portion of the gums.
Opposite the canine fossa this nerve communicates
with the anterior dental nerve. The other posterior
dental nerve continues its course forward external to
the bone, and is distributed to the gums and the
buccinator muscle.

The Middle and anterior dental branches are given off
in the infra-orbital canal, and descend to the correspond-
ing teeth and to the gums. The middle passes beneath
the lining membrane of the antrum, whilst the anterior
passes through a special canal in the anterior wall of
that cavity. Previously to their distribution, the
anterior, middle, and posterior dental nerves, form a
plexus (the superior maadllary pleocus) in the outer wall
of the superior maxillary bone, immediately above the
alveolus, from which filaments are given off to supply
the pulps of the teeth, gums, mucous membrane of the
floor of the nares and the palate.

The Palpebral, nasal and labial branches are very
numerous, and supply the muscles and skin of the
regions indicated by their names. The palpebral also
supplies the conjunctiva of the lower eyelid, and com-
municates with the facial nerve and the malar branch

of the orbital. The nasal branches communicate with
the nasal branch of the ophthalmic nerve.

Note. — ^The second division of the 5th nerve is entirely
sensory in function. It is the nerve of sensation of
teeth, of the upper jaw, the hard and soft palate,
gums, tonsils, antrum maxillare, muscles, skin and con-
junctiva of the lower eyelid, mucous membrane of the
floor of the nares, and the muscles and skin of the
cheeks and upper lip.

(cj. — The Inferiob Majollaet Nerve.

This, the largest division of the flfth nerve, consists
of two portions, the sensory, which arises from the
inferior angle of the Gasserian ganglion, and passes
through the foramen ovale in the spheniod bone with
the motor portion which, as above stated, passes beneath
the ganglion, and unites with the sensory portion just
as it makes its exit from the cranium. Immediately
beneath the base of the skull, the nerve again divides
into two trunks, an anterior and posterior, the former
of which receives nearly all the motor fibres. These
again subdivide into numerous branches as foUows : —

Anterior Division, Posterior Division.

Masseteric. Auriculo-Temporal.

Deep Temporal (2). Inferior Dental

Buccal. Gustatory.
Pterygoid (2).

The Masseteric branch passes outwards above the
external pterygoid muscle, behind the tendon of the
temporal muscle and in front of the temporo-maxillary
articulation crosses the sigmoid notch with the masse-
teric artery, and enters the masseter muscle. It sends
a small branch to the temporal muscle, and a filament
to the temporo-maxillary articulation.

The Deep Temporal hrancheSy two in number, anterior

and posterior, pass between the upper border of the
external pterygoid muscle, and the temporal bone to
roach the deep surface of the temporal muscle which
they supply. Some filaments from these nerves pierce
the temporal fascia and communicate with the larchry-
mal, subcutaneus malse, superficial temporal and facial
nerves.

The Buccal Branch pierces the lower fibres of the
external pterygoid muscle, to which it gives a branch,
and passes downwards, beneath the inner surface of the
coronoid process of the lower jaw, or through the fibres
of the temporal muscle to reach the surface of the
buccinator muscle which it supplies, as also the skin
and mucous membrane of the cheek. It also sends a
few filaments to the temporal muscle, and communi-
cates with the facial nerve.

The PierygoidbrancJieSy two in number, internal and ex-
ternal, supply the internal and external pterygoid muscles
respectively. The internal branch is intimately con-
nected with the otic ganglion and also gives filaments
to the tensor palati and tensor tympani muscles. The
external branch may arise separately from the inferior
maxillary nerve, but more commonly it is given off
from the buccal nerve.

The Atjriculo-Tempobal Nekvb usually arises by
two roots between which passes the middle meningeal
artery. It then passes backward behind the temporo-
maxillary articulation, turns upward between the
articulation and the meatus of the ear and escaping
from beneath the parotid gland, divides into two
temporal branches. While behind the articillation, it
forms a kind of plexus and gives off different branches.
The branches are : —

TemporO'Maxillary^ a small branch to the articula-
tion.

Parotidean; two or three filaments to the parotid
gland.

Branches to the Meatus Avditorius, two in number,
which enter the canal between the fibro-cartilage and
processus auditorius.

Auricuilar; two in number, superior and inferior;
these are distributed to the pinna above and below the
meatus. The inferior branch communicates with the
sympathetic.

Communicating branches, with the otic ganglion and
facial nerve.

Temporal Branches (terminal), two in number,
anterior and posterior. The anterior accompanies the
temporal artery to the vertex of the skull, supplies the
skin of the temporal region, and communicates with
the facial, subcutaneus malse, supra-orbital and larchry-
mal nerves. The posterior supplies the attrahens
aurem muscle, the upper part of the pinna and skin of
the posterior part of the temple.

The Infbeior Dental Nerve, the largest of the three
branches of the posterior division of the fifth nerve,
passes downwards accompanied by the inferior dental
artery, at first between the two pterygoid muscles, and
then between the internal lateral ligament and the
ramus of the lower jaw to the dental foramen which it
enters. It then runs along the canal in the lower jaw,
distributing branches in its course to the molar and
bicuspid teeth and to the gums, and at the mental
foramen, divides into two terminal branches, the incisive
and mental. The incisive branch is continued forward
within the bone as far as the symphisis, and supplies
the canine and incisor teeth. The mental branch emerges
from the jaw at the mental foramen, beneath the
depressor anguli oris muscle, and divides into branches

which supply the depressor anguli oris, the orbicularis
oiis and quadratus menti muscles, and the mucous
membrane and skin of the lower lip. It also com-
municates with the facial nerve. In addition to the
branches above mentioned, the inferior dental gives off
an important branch just before it enters the inferior
dental foramen, viz : — the mylo-hyoidean branch. This
nerve having pierced the insertion of the internal
lateral ligament, descends in a well-marked groove on the
inner surface of the lower jaw, to the my lo-hyoid muscle,
which it supplies, a small branch being prolonged
forward to supply the anterior belly of the digastrious.

The Gustatoby Nerve (sometimes called the lingual,)
arises from the posterior division of the inferior maxil-
lary nerve, and descends between the internal and ex-
ternal pterygoid muscles a little to the inner side of
the inferior dental nerve. Below the border of the
external pterygoid, it curves forward between the
internal pterygoid and the ramus of the jaw, and
crosses obliquely over the superior constrictor of
the pharynx and between the stylo-glossus muscle
and the sub-maxillary gland, to the side of the
tongue, along which it runs, crossing Wharton's
duct to reach the tip. This nerve supplies branches
to the mucous membrane of the mouth and
gums, the sub-lingual glands, and the papillae and
mucous membrane at the sides and tip of the tongue.
It also sends branches of communication to the sub-
maxillary ganglion, and to the hypoglossal nerve.
These latter form a plexus at the anterior margin of
the hyo-glossus muscle. While between the pterygoid
musdes it receives a branch of communication from the
ii^erior dental nerve, and a little lower down it is
joined by the chorda tympani from the facial. After
communicating with the gustatory, the chorda tympani

is continued downwards in its sheath to the sub-
maxillary ganglion.

Note. — The third division of the fifth nerve has a
throe-fold fanction. It is one of the special nerves of
the sense of taste ; it supplies common sensation to the
tongue, the skin of the temple, external ear, lower part
of the face, lower lip and other parts to which it is dis-
tributed, and it supplies the power of motion to the
muscles of mastication (except the buccinator,) the
mylo-hyoideus and anterior belly of the digastricus.

XLI. — The Ganglia op the fifth pair of Nebvbs.

In addition to the Gasserian ganglion (already des-
cribed) there are in intimate connection with the fifth
pair of nerves, four other ganglia, viz : —

(a) The ophthalmic or lenticular ganglion.

(h) The spheno-palatine or Meckel's ganglion.

(d) The submaxillary ganglion.

It may be as well to consider these ganglia here,
although properly speaking, they belong to the cranial
portion of the sympathetic system of nerves.

(a) The Ophthalmic Ganglion.

The ophthalmic or lenticular ganglion, is a small
quadrangular and flattened ganglion, situated at the
back of the orbit on the outer side of the optic nerve
and near the ophthalmic artery. It has three roots
entering into its formation (branches of communication)
— sensory, motor and sympathetic.

The sensory or Isng root, the most superior, joins the
ganglion at its superior angle, and is derived from the
nasal branch of the first division of the fifth nerve.

The motor or short root^ the moftt \\iiaTV'Jst^ \'»as!» *<^^

ganglion at its inferior angle and is derived from the
inferior division of the third nerve.

The sympathetic root is a long slender filament which
enters the ganglion between the other two roots, and
is derived from the carotid plexus of the sympathetic
nerve.

Occasionally the ganglion receives a branch of com-
munication from the spheno-palatiue ganglion.

The branches of distribution are the short ciliary
nerves which arise from the anterior angles in two
groups. The upper group consists of about four
filaments, the lower of five or six. They pierce the
sclerotic around the optic nerve, to supply the tunics of
the eyeball.

(h) The Sphbno-Palatine GANOLioisr.

The Spheno-palatine or Meckel's Ganglion is situated
in the spheno-maxillary fossa, opposite the spheno-
palatine foramen, and a little below the superior
maxillary nerve. It has three roots — sensory, motor,
and sympathetic.

The sensory root is jfrom the superior maxillary
nerve, by means of the two spheno-palatine nerves.

The motor root is derived through the Vidian nerve
from the facial nerve, {vide posterior branches.)

The sympathetic root is from the carotid plexus of the
sympathetic nerve.

The branches of distribution of the ganglion are divided
into four sets, ascending, descending, internal, and
posterior.

The ascending branches are three or four small fila-
ments, which are distributed to the periosteum of the
orbit. One of these branches sometimes joins the
ophthalmic ganglion.

The descending branches are the anterior, middle, and
posterior palatine nerves. The anterior or great palatine
nerve descends from, the ganglion, through the posterior
palatine canal, and emerging from the posterior palatine,
foramen is distributed to the hard palate. It also
communicates with the naso-palatine nerve. While in
the posterior palatine canal, the anterior palatine nerve
gives off several branches (inferior nasal) which are
distributed to the middle, and inferior meatus of the
nose. The middle or external palatine nerve passes
through the posterior palatine foramen, and is distributed
to the tonsil, sofb palate and uvula. The posterior or
small palatine nerve emerges from an opening behind
the posterior palatine foramen and is distributed to the
gums, soft palate and uvula.

The internal branches are the superior nasal and
naso-palatine. The superior nasal nerves are four or
five in number, which enter the nasal fossa through the
spheno-palatine foramen, and are distributed to the mu-
cous membrane of the superior meatus, and the superior
and middle spongy bones. The naso-palatine nerve also
enters the nasal fossa through the spheno-palatine
foramen and crossing the roof of the nares reaches
the septum, to which it gives filaments and passes
downwards and forwards along the vomer and through
the naso-palatine canal to reach the palate to which it
is distributed.

The posterior branches are the Vidian or pterygoid
nerve and the pterygopalatine.

The Vidian nerve passes directly backwards through
the pte rygoid or Vidian canal to the foramen lacemm
basis cranii, where it divides into two branches, carotid
and jpetrosal. The carotid branch or deep ^ett^^^^i.
nerve crosses the foiameu laeeiMaa. «xA ^"^«r^ '"^'^

carotid canal to johi the carotid plexus. The petrosal
branch or nervus petrosus superficialis major, enters
the cranium at the foramen lacerum basis cranii,
and passes backwards beneath the Gasserian ganglion
and dura mater, embedded in a groove on the
anterior surface of the petrous portion of the
temporal bone, to reach the hiatus Eallopii. Here
it receives a branch jfrora Jacobson's nerve, and
terminates in the intumescentia gangliformis of the
facial nerve. The pterygo-^dlatine nerve is a small
branch which passes backwards through the pterygo-
palatine canal and is distributed to the mucous
membrane of the Eustachian tube and neighbouring
part of the pharynx.

The Otic, or Arnold's ganglion, is a small oval-
shaped ganglion, which may be found near the fora-
men ovale, lying against the inner surface of the infe-
rior maxillary nerve (third division of 5th). It is
closely adherent to the internal pterygoid nerve, and,
posteriorly, it is in contact with tlie middle meningeal
artery.

It has three roots — motor, sensory, and sympa-
thetic. The motor, or short root, is derived from the
inferior maxillary nerve; the sensory, or long root,
from the auriculo-temporal nerve, and the nervus pet-
rosus superficialis minor, and the sympathetic from
the nervi molles of the meningeal artery. These are
sometimes called branches of communication. The
branches of distribution are, a small filament to the
tensor tympani muscle and one or two filaments to the
tensor palati.

Note. — The nervus petrosus superficialis minor

ascends from the otic ganglion to a small cftnal situated
between the foramen ovale and foramen spinosum, and
passes backwards on the petrous bone to the hiatus
Fallopii, where it divides into two filaments. One of
th^e filaments enters the hiatus and joins the intu-
mescentia gangliformis of the facial nerve ; the other
passes to a minute foramen near the base of the
petrous bone, and enters the tympanum, where it com-
municates with a branch of Jacobson's nerve (Wilson.)

(d) The Sitb-MaxttiLaky Ganglion.
This ganglion is situated on the sub-maxillary gland,
a little below the gustatory (br. of 5th) nerve. Its
roots, or branches of communication, are as fol-
lows : —

MotoTf the chorda tympani from the facial (7th)
nerve;

Sensory, two or three filaments from the gustatory
nerve.

Sympathetic; one or two filaments from the plexus
on the facial artery, which connect it with the cervical
portion of the sympathetic.

The branches of distribution are six or eight fila-
ments, which supply the side of the tongue, the sub-
maxillary gland, sublingual gland, and Wharton's
duct.

XLII. — The Sixth Paie op Nbbves.

Origin, The sixth or abducens nerve arises by seve-
ral filaments from the upper constricted part of the
corpus pyramidale, and by a few filaments from the pons
Varolii. This is its superficial origin, but according to
some anatomists, its deep origin may be traced between
the fasciculi of the corpora pyramidalie t^ t^L'^^^'^iwscsjst

part of the medulla oblongata, and to the grey sub-
stance of the fourth ventricle.

Course, From the above origin — superficial — ^the
nerve passes forward parallel with the basilar artery
and pierces the dura mater to reach the cavernous
sinus. It then runs forward through the sinus below
the level of the other nerves, and resting against the
internal carotid artery, to the sphenoidal fissure, through
which it passes to enter the orbit.

Distribution, This nerve is specially distributed to
the external rectus muscle, which it supplies with
motor power.

XLIII. — The Seventh Pair op Nebves.

The seventh pair of nerves consists of two distinct
■nervous cords, which differ from each other, both in
structure and in function. These two. cords lie side by
side on the posterior border of the crus cerebelli. The
most internal, which is also smaller and more dense in
structure, is called the jportio dura, or facial nerve.
The external is soft and pulpy, and is called the^or^to
mollis, or auditory nerve. Connecting the two nerves
is a small nerve known as the jportio intermedia of
Wrisberg, which is regarded by some anatomists as
the posterior or sensitive root of the facial ; that the
intwmescentia gangliformis of the facial nerve is the
ganglion of this root ; and that it bestows sensory func-
tions on the facial. The origin, course, and dLstribu-
tion of the facial and auditory nerves must be considered
separately.

(A) The Portio Duba, ob Facial Nerve.

Origin. The superficial origin of the nerve is the

lateral tract of the medulla oblongata at the upper

part of the groove between the olivary and restifonn

bodies. A few fibres arise from the pons Varolii. The
deep origin is said to be a grey nucleus in the floor of
the fourth ventricle.

Course, — From the above origin (superficial) the
nerve passes forwards and outwards, resting on the
cms cerebelli, and enters the internal auditory meatus
with the auditory nerve, lying at first to the inner side
of, and then upon, that nerve. At the bottom of the
meatus it enters the aqueductus Fallopii, and passes for-
wards and outwards to the hiatus Fallopii in the ante-
rior wall of the petrous bone, where it • receives the
petrosal branch of the Vidian nerve, and forms a gang-
liform swelling, which is known as the intumescentia
gangliformis, or ganglion geniculare. It then curves
backwards and descends in the anterior wall of the
tympanum to the stylo-mastoid foramen. From
the foramen the nerve passes forward, enters the
parotid gland, crosses the external carotid artery, and
divides opposite the ramus of the jaw into two primary
trunks — temporo-fadal and cervico-facial.

In its course from the brain to the ramus of the jaw
the facial nerve has several important communications
with other nerve structures, which Gray tabulates
thus : —

In the internal audi- ( xtt'i-x. xt. j'i.

, , -j With the auditory nerve.

^ With Meckel's ganglion by
the large petrosal nerve.

In the aqueductus
Fallopii.

With the otic ganglion by
the small petrosal nerve.

With the sympathetic on
the middle meningeal ar-
tery by the external petrosal

v^nerve.

("With the pneamogastric.
At its exit from the J " " glos^PWngeal.
stylo-mastoid foramen. < » " <"«?tid plexus.
^ „ „ aunculans magnns.

^ „ „ auriculo-temporal.

In addition to the above communications, it com-
municates by means of its terminal branches on the
face, with the three divisions of the fifth nerve.
Distribution. — The branches of distribution are
divided into three sets : (a) Branches given off
within the aqueductus Fallopii; (h) Branches
given off at its exit from the stylo-mastoid fora-
men ; (c) Branches given off on the fkce.
(a) Branches given off within aqueductus Fallopii.

(i.) Tympanic^ a small filament to the stapedius and
laxator tympani muscles.

(ii.) Chorda tympani, a branch given off just before
the nerve makes its exit from the stylo-mastoid
foramen. It ascends by a distinct canal to
the upper part of posterior wall of the tympa-
num and enters that cavity through an opening
between the base of the pyramid and the attach-
ment of the membrana tympani. It then
crosses the tympanum between the handle of
the malleus and long process of the incus,
and makes its exit through an opening in the
Glasserian fissure known as the canal of Huguier.
Having emerged from the skull, it passes down-
wards between the two pterygoid muscles, joins
the gustatory nerve at an acute angle, and de-
scends to the submaxillary ganglion, of which
it forms the motor root [vide Aid xli. (c?)],
and finally terminates in the lingualis muscle.
(h) Branches given off at its exit from stylo-mastoid
foramen.

(i.) Posterior auricular^ a branch given off close to
the foramen, which ascends behind the ears and
between the meatna and mastoid process, di-
vides into two branches, anterior- and pos-
terior. The anterior, or auricular branch, com-
municates with the auricular branch of the
pneumogastric nerve and supplies the retrahens
aurem and skin of the auricle. The posterior,
or occipital branch, communicates with the great
auricular and small occipital nerves, and is dis-
tributed to the occipital portion of the occipito-
frontalis and the skin at back of the head.

(ii.) Styh'hyoid, a long, slender branch which com-
municates with the sympathetic plexus on the ex-
ternal carotid and supplies the stylo-hyoideus.

(iii.) Digastric, a branch which supplies the poste-
rior belly of the digastricus and communicates
with the glosso-pharyngeal nerve.

On the face, and while still in the parotid gland,
the facial nerve divides into two primary divi-
sions — ^temporo-facial and cervico-facial. Each
of these almost immediately subdivides into
three sets of branches, constituting the
plexus known as the pes anserinus. The tem-
poro-fadal is the larger of the two terminal
branches. It communicates wjth the auriculo-
temporal nerve. Its three sets of branches are
(i.) Temporal, (ii.) Malar, (iii.) Infra-orbital.

(i.) Temporal Branches, — These ascend to the tem-
poral region, supplying the attrahens aurem
muscle and skin, frontal portion of oceipito-
frontalis and orbicularis palpebrarum, and com-
municates with the supra-orbital nerve and
temporal branch of superior Taax\\L^^ \^<5st^^.

(ii.) Malar Branches. — ^These cross the malar bone
to reach the outer angle of the eye and supply
the orbicularis palpebrarum and corrugator
supercilii muscles and skin of the lower eyelid.
They also communicate with the supra-orbital
nerve, and the subcutaneus malsB.

(iii.) Infra-orbital Branches. — ^These pass horizon-
tally forward in two sets. The superficial set
supply the skin and superficial muscles of the
face between the lower margin of the orbit and
the mouth, the pyramidalis nasi muscle and
lower eyelid. The deep set supply the levator
labii superioris and levator anguli oris muscles,
and beneath these muscles join with the infra-
orbital nerve (superior maxillary) to form the
infra-orbital plexus. The infra-orbital branches
of the facial nerve also communicate with the
infra-trochlear and nasal nerves.

The cervico-facial division passes downwards and
forwards, and opposite the angle of the lower jaw,
divides into its terminal sets of branches. These are :
(1) Buccal ; (2) Supra-maxillary ; (3) Infra-maxillary.

(i.) Buccal Branches, — These are distributed to
the orbicularis oris and buccinator muscles, and
communicate with the temporo-facial division,
and with the buccal branch of the inferior
maxillary nerve.

(ii.) Supra-MaanUary Branches. — These supply
the muscles of the lower lip and chin, and
communicate with the mental branch of the
inferior dental nerve.

(iii.) Infra-Maanllary Branches. — ^These take
their course downwards and forwards below the
lower jaw, and supply the platysma myoides and
communicate with the superficial cervical nerve.

(B), The Porho Mollis, or Attditoet Nbeve.

Origin, — From the linesB transverssB of the anterior
wall or floor of the fourth ventricle. It also receives
a few fibres from the restiform body, and is said to be
connected with the grey matter of the medulla oblongata.

Course, — From the fourth ventricle the nerve winds
around the restiform body to the posterior border of the
cms cerebelli. It then passes forward on the cms
with the facial nerve and enters with the latter the meatus
audit orius intemus. At the bottom of the meatus it
divides into two branches, cochlear and vestibular.

Distribution, — The cochlear division, the anterior of
the two divisions, subdivides into numerous filaments
which enter the foramina spiralis in the base of the
cochlea, pass upwards in the canals of the modiolus,
and then between the layers of the osseous lamina
spiralis. Here the nerve filaments form a network from
which branches are given off which perforate the bot-
tom of the sulcus spiralis, and are supposed to termi-
nate in the rods of Corti. The central portion of the
nerve passes through the tubulus centrafis modioli, and
supplies the apical portion of the lamina spiralis and
adjoining structures. The vestibular division subdivides
into three branches, superior, middle, and inferior.
The superior gives off a number of filaments, which
pass through the foramina in the posterior part of the
superior depression, enter the vestibule, and are distri-
buted to the ventricle and the ampulla of the superior
and external semicircular canals. The middle sends
off numerous filaments, which pass through the foramina
in the lower depression, enter the vestibule through the
fovea hemispherica, and are distributed to the saccule.
The inferior passes along the groove and through the
foramen at the back part of the meatus, to be distributed
to the ampulla of the posterior canaV. (^'-^^ovO^

XLTV. — ^Thb Eighth Paib op Nerves.

The eighth pair of nerves of Willis consists of three
distinct pairs: — A, glosso-pharyngeal ; B, pneumo-
gastric ; and C. spinal accessory. These are respectively
the eighth, ninth, and tenth pairs of Soemmering.

A. The Glosso-Pharyngeax Nerve.

Origin, — (Superficial.) From the groove at the upper
part of the medulla oblongata between the olivary
and restiform bodies. The deep origin has been
traced through the fasciculi of the lateral tract to a
grey nucleus in the floor of the fourth ventricle.

Course, — From the above superficial origin it passes
outwards across the flocculus, and leaves the skiUl en-
closed in a separate sheath of dura mater at the jugular
foramen, lying anteriorly to the pneumogastric and
spinal accessory nerves, and internally to the jugular
vein. It then passes forward between the jugular vein
and internal carotid artery to reach the posterior border
of the stylo-pharyngeus. It then curves inwards,
passing over the stylo-pharyngeus and middle constric-
tor and behind the hyo-glossus muscle, to be distributed
to the tongue, pharynx, and tonsil.

In the jugular fossa the nerve presents two gangli-
form enlargements, superior and inferior. The superior
or ganglion jugulare is of small size and involves only
the posterior fibres of the nerve. The inferior, or
ganglion of Andersch, is larger in size and involves the
whole of the nerve. It is lodged in a depression in
in the lower border of the petrous portion of the tem-
poral bone, and is hence also known as the petrous
ganglion. It gives off the following branches of commv^
nieation: — (i.) One to the auricular branch of the
pneamogasirie. (ii.) One to the upper ganglion of

the pneumogastric. (iii) One to the superior ganglion
of the sympathetic. Below the ganglion the nerve-
gives off a branch of communication with the facial..

DtstribiUion. — The branches of distribution are divided
into six sets : — (i.) Tjrmpanic ; (ii.) Carotid ; (iii.) Mus-
cular ; (iv.) Pharyngeal ; (v.) Tonsillitic ; (vi.) Lingual.

(i.)- The Tympanic, or Jacobson's nerve, arises from
the ganglion of Andersch, or from the trunk of the
nerve above the ganglion, and enters a small bouy canal
in the petrous portion of the temporal bone to roach
the tympanum. It divides into six branches: three
branches of communication (one to carotid plexus of
sympathetic, one to the greater superficial petrosal
nerve, and one to the otic ganglion,) and three branches
of distribution — one to fenestra rotunda, one to fenestra
ovalis, and one to lining membrane of the Eustachian
tube and tympanum, (ii) Carotid branches, — These
are several filaments which follow the trunk of the
internal carotid artery, and join the nervi molles of
the sympathetic, (iii.) Muscular branches to stylo-
pharyngeus and constrictor muscles, (iv.) Pharyn-
geal branches. — These are three or four in number,
and supply the mucous membrane of the pharynx after
joining with the pharyngeal branches of the pneumo-
gastric and sjrmpathetic nerve opposite the middle
constrictor muscle to form i^e pharyngeal pleocus. (v.)
Tonsilliticbranches, — These form a plexus around the base
of the tonsil — circulus tonsillaris — ^from which branches
are given off to the fauces and soft palate, and to
communicate with the descending palatine nerves,
(vi.) Lingual branches, — These are two in number^
and are distributed to the sides and base of the tongue.

B. The Pnetjmogastkic ob Vagits Nerve.
Origin, — (Superficial) By ten ot ^\»r?q. ^«2SNK«is»r

from the lateral tract immediately behind the olivary
body, below the origin of the glosso-pharyngeal. Its
deep origin may be traced through the restiform body
to a grey nucleus on the floor of the fourth ventricle.

Course, — From the above origin the nerve passes
outwards to the jugular foramen, through which it
makes its exit from the skull, enclosed with the spinal
accessory nerve in a sheath derived from the dura mater.
Whilst in the jugular foramen, the nerve presents a
small ganglion, called the superior or jugular ganglion.
It is also known as the ganglion of the root. Just
below the fossa the nerve presents a larger gangli-
form swelling, called the ganglion of the trunk,
or inferior ganglion. To the superior ganglion
the accessory part of the accessory nerve is attached.
After the nerve has emerged from the skull, it takes its
course down the side of the neck, enclosed in the same
sheath as the internal and external carotid artery lying
at first between the internal carotid artery and internal
jugular vein. When at the level of the thyriod carti-
lage, the nerve lies between the common, carotid artery
and the vein, and continues in relation with these ves-
sels to the root of the neck. Below this point the
course of the nerve is different on each side. The right
nerve enters the chest by passing between the subcla-
vian artery and vein, and descends by the side of the
trachea to the back part of the root of the lung, where
it forms a network of nerves, the posterior pulmonary
plexus. From the plexus the nerve proceeds in two
cords along the posterior aspect of the oesophagus. At
the lower part of the oesophagus the two cords reunite,
and are continued on to the posterior surface of the
fltomach. The left nerve enters the chest between the left
carotid and subclavian arteries, and behind the left inno-
minate vein, crosses the arch of the aorta, and descends
to the posterior part of the root of the left lung. It is

then continued downwards along the anterior aspect of
the stomach. Prom the ganglia several branches of com-
munication are given off thus : — From the superior,
filaments to the spinal accessory, the superior
ganglion of the sympathetic and to the inferior ganglion
of the glosso-pharyngeal. From the inferior, filaments to
the hypoglossal, the superior ganglion of the sympathetic,
and to the loop between the 1st and 2nd cervical.

Distribution, — ^The branches of distribution are : — (i.)
Auricular ; (ii.) Pharyngeal ; (iii.) Superior laryngeal
(iv.) Cardiac; (v.) Inferior or recurrent laryngeal
(vi.) Anterior Pulmonary ; (vii.) Posterior Pulmonary
(viii.) (Esophageal ; (ix.) Gastric.

(i.) The Auricular branch, or Arnold's nerve, is given
off in the jugular fossa, and after receiving a branch of
communication from the glosso-pharyngeal, passes out-
wards to a small opening in the petrous portion of the
temporal bone near the stylo-mastoid foramen. It then
enters this opening to reach the descending part of the
aqueductus Fallopii, where it gives off two branches,
one to the facial and one to communicate with the auri-
cular branch of the facial. The continuation of the
nerve supplies the skin over the back part of the pinna.

(ii.) The Pharyngeal branch arises from the inferior
ganglion, and after receiving a filament from the acces-
sory portion of the spinal accessory nerve, passes behind
the internal carotid artery to reach the middle constric-
tor, upon which muscle it joins the pharyngeal plexus.

(iii.) The Superior Laryngeal arises from the inferior
ganglion, and descends behind the internal carotid artery
to the opening in the thyro-hyoidean membrane, which
it enters with the superior laryngeal artery to supply
the mucous membrane of the interior of the larynx, and
the arytenoideus muscle, Whilst behind the artery it
gives off the external laryngeal nerve, which «vl^^^^^^

the superior constrictor and crico-thyroid muscles, and
sends a filament to join the pharyngeal plfexus.

(iv.) The Cardiac branches are in two sets, cervical
and thoracic. The cervical are two or three branches,
which arise from the cervical portion of the nerve. The
largest branch of the set is given off just before the
pneumogastric enters the chest. On the right side
this branch — the inferior cardiac nerve — descends by
the side of the innominate artery to join the deep car-
^ac plexus. On the left side it passes in front of the
^irch of the aorta to join the superficial cardiac plexus.
The thoracic cardiac nerves on the right side arise from
the trunk of the pneumogastric, and on the left they
are given off from the recurrent laryngeal nerve. In
each inatance they join the deep cardiac plexus.

(v.) The Inferior or Recurrent Laryngeal Nerve arises
on the right side, in front of the subclavian artery, and
winds around that vessel from before backwards. It
then ascends to the side of the trachea, passing behind
the common carotid and inferior thyroid arteries. On
the left side the nerve curves around the arch of the
aorta and ascends to the trachea. Each nerve ascends
in the groove between the trachea and oesophagus, and
pierces the inferior constrictor muscle to reach the
larynx. It is distributed to all the muscles of the
larynx the crico-thyroid excepted.

(vi.) The Anterior Pulmonary branches are two or
three in number. With branches from the cardiac
plexiises they form the anterior pulmonary plexus, and
wre distributed to the anterior aspect of the root of
tW lung. The Posterior Pulmonary branches join the
posterior pulmonary plexus and are distributed to the
posterior aspect of the root of the lung.

(vii.) The (Esophageal branches axe given off above

the root of the lungs. They form a plexus around the
oesophagus known as the plexus gutm, and freely com-
municate with each other,

(viii.) The Gastric branches are the terminal fila-
ments of the nerve. The left nerve supplies the an-
terior aspect of the stomach, and the right the posterior.
The right communicates with the solar and splenic
plexuses, and the left with the hepatic plexus.

C. — ^ThB SPESTAi ACOBSSOBT NbEVE.

Origin, — ^By several filaments from the side of the
spinal cord, as low down the fifth or sixth cervical
nerve. There is a small accessory portion which arises
from the lateral tract below the origin of the vagus.
The deep origia of this portion may be traced to a grey
nucleus in the floor of the fourth ventricle.

Course, — From the above origin the nerve ascends
behind the ligamentum dentatum, and between the
roots of the spinal nerves to the foramen lacerum pos-
tesius. It makes its exit from the skull enclosed in
the same sheath of dura mater as the pneumogastric,
and then passes downwards and outwards behind the
internal jugular vein to to the upper part of the stemo-
mastoideus. It pierces this muscle obliquely and
crosses the posterior triangle of the neck to terminate
in the trapezius. In its course it sends communicating
branches to the pneumogastric nerve, the cervical
plexus, and the third and fourth cervical nerves.

Distribution, — The branches of distribution are nerves
of supply to the sterno-mastoideus and trapezius.

XLV. — The Htpoglossax oe Ndtth Paib of Nbkvbs.
Origin, — The superficial origin of this nerve is by

ten or fifteen filaments from the groove between the
oliyary and pyramidal bodies. Its deep origin, it is
said, may be traced to a grey nucleus in the floor of
the fourth ventricle near the nuclei of the glosso -pha-
ryngeal and pneumogastric nerves.

Course, — From the above superficial origin, the
nerve passes forward through the anterior condyloid
foramen, and then downwards and forwards between
the internal carotid artery and internal jugular vein
until it becomes parallel with the angle of the lower
jaw. It then curves forward around the occipital
artery, crosses the external carotid and passes beneath
the mylo-hyoideus between it and the hyo-glossus. It is
then continued ii^ito the genio-hyoglossus and sends
filaments onwards as far as the tip of the tongue. In its
course it communicates with the pneumogastric, sym-
pathetic, first and second cervical, and gustatory nerves.

Distribution, — ^The branches of distribution are, — (i.)
Descendens noni ; (ii.) Thyrp-hyoidean ; (iii.) Muscular.

(i.) Descendens rtoniy a long slender branch, which is
given off just as the hypoglossal loops around the oc-
cipital artery. It descends on the sheath of the caro-
tid vessels, and just below the middle of the neck it
forms a loop with the communicans noni nerve from
the 2nd and 3rd cervical. From this loop are given
off nerves of supply to the stemo-thyroideus and both
bellies of the omo-hyoideus. (ii.) The Thyro-hyoidean
nerve is a small branch which is given off from the
hypoglossal, near the posterior border of the hyo-
glossus muscle. It supplies the thyro-hyoideus.
(iii.) Muscular. — These are several branches which
are given off beneath the mylo-hyoideus to supply the
stylo-glossus, hyo-glossus, genio-hyoid, and genio-hyo-
glossus muscles.

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