D. J. (Daniel John) Cunningham.

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acromial vessels, and the lateral anterior thoracic nerve.
Note (i) that the fibres of the membrane run medio-laterally,
(2) that they are put on the stretch when the arm is abducted,
and (3) that they are relaxed when the arm is by the side. The
surgeon takes advantage of these facts when he is ligaturing
the first part of the axillary artery.

Clavicle

Subclavius

Thoraco-acromialarter. ^^^^^.^ ,, , .^^

_ First rib




Axillary artery
Axillary sheath



Axillary fascia

FIG. 12. Diagram of the Costo-coracoid Membrane.

Dissection. Cut through the anterior layer of the upper part
of the costo-coracoid membrane and expose the subclavius
muscle. Pass the handle of a knife below the lower border of
the subclavius and upwards behind the muscle and demonstrate
the posterior layer of the upper part of the membrane. Clear away
the remains of the membrane and follow the cephalic vein to its
junction with the axillary vein, the thoraco-acromial artery to
the axillary trunk, and the lateral anterior thoracic nerve to the
lateral cord of the brachial plexus. Clean the proximal parts of
the axillary artery and vein and the lateral cord of the brachial
plexus. Note that the axillary vein lies to the medial side of the
artery, on a somewhat anterior plane, and that as the arm is
abducted from the side the vein passes more and more in front
of the artery. The lateral cord of the plexus lies to the lateral
side of the artery and on a posterior plane. Behind the upper
border of the pectoralis minor find the medial anterior thoracic
nerve, and note that a communication is formed between the
medial and lateral anterior thoracic nerves, across the front of
the axillary artery and behind the costo-coracoid membrane.



26 THE SUPERIOR EXTREMITY

Clean the pectoralis minor muscle without injuring the medial
anterior thoracic nerve, which pierces it.

M. Pectoralis Minor. The pectoralis minor muscle is
triangular in outline. It arises (i) from the anterior ends
of the third, fourth, and fifth ribs, close to their junctions
with their cartilages, and (2) from the fascia covering the
intercostal muscles in the intervening spaces. Its fibres pass
upwards and laterally, and its tendon of insertion is attached
to the upper surface and the antero- medial border of the
horizontal part of the coracoid process, near its lateral
extremity. When the muscle is in action it draws the scapula
downwards and forwards, and depresses the shoulder. It
is supplied by the medial anterior thoracic nerve. The greater
portion of the pectoralis minor is concealed by the pectoralis
major, but the lower and medial part of its inferior border
appears on the lateral wall of the thorax below the pectoralis
major ; its insertion is concealed by the anterior fibres of the
deltoid.

Dissection. Clear away the clavipectoral fascia below the
level of the pectoralis minor and open up the lower part of the
axilla ; remove also the deep fascia of the arm in the region of
the lateral boundary of the axilla.

Commence at the lateral part of the area below the pectoralis
minor and clean the coraco-brachialis and the short head of the
biceps, as they descend into the arm from the tip of the coracoid
process. Find the distal part of the axillary artery at the medial
border of the coraco-brachialis. The trunk of the median nerve
lies between the artery and the muscle, and at the lower border
of the pectoralis minor the medial head of the nerve crosses the
front of the artery. Pull the coraco-brachialis laterally and find
the musculo-cutaneous nerve entering its deep surface, just
below the pectoralis minor. Above and to the lateral side of the
trunk of the musculo-cutaneous nerve find the branch from it
which supplies the coraco-brachialis. The axillary vein lies along
the medial side of the artery, and in the interval between the
artery and vein, anteriorly, is the medial cutaneous nerve of the
forearm (O.T. internal cutaneous). Running along the medial
side of the vein is the medial cutaneous nerve of the arm (O.T.
lesser internal cutaneous nerve) ; secure it and follow it upwards
to the communication which it receives from the intercosto-
brachial nerve (Fig. 13). At the same time identify and
preserve the lateral group of axillary lymph glands, which lie
along the medial side of the axillary vein. Secure the intercosto-
brachial nerve and follow it medially, to the point where it
emerges from the second intercostal space, and laterally to the
medial and posterior aspect of the arm, where it is distributed.

In order to display the distribution of the intercosto-brachial
nerve, and to give better access to the medial and posterior walls
of the axilla, the axillary fascia must be separated from the fascia



AXILLARY SPACE



27



of the arm. When that has been done the dissector should turn
to the medial wall of the axilla and find the anterior and posterior
divisions of the lateral branches of the intercostal nerves, as they



Posterior circumflex artery
Subscapular artery



\



Musculo-cutaneous nerve
Axillary nerve (O.T. circumflex)

Cephalic vein
Acromial artery '
Lateral anterior thoracic nerve '
Lateral cord of brachial plexus

Thoraco-acromial artery '
Axillary artery, ist part

Axillary vein
Subclavius muscle

Medial anterior
thoracic nerve

Pectoral branch
of thoraco-
acromial artery



Anterior circumflex artery
; Pectoralis major

/ Coraco-brachialis
Biceps brachii
(short head)




I Basilic vein
Brachial artery
Median nerve

Fascial band connecting lat.
dorsi with long head of triceps
Medial cutaneous nerve of the

forearm
Ulnar nerve



\J\ Medial cutaneous nerve of the arm

', Teres major

Radial nerve (O.T. musculo- spiral

Circumflex artery of scapula (O.T.
1 dorsalis scapulae)
Lower subscapular nerve

Subscapularis mascle

! Posterior division of a lateral cutaneous nerve
Latissimus dorsi
Thoraco-dorsal nerve (O.T. middle subscapular)



Anterior branch of a
ateral cutaneous nerve



Long thoracic nerve
/ Intercosto-brachial nerve

Lateral thoracic artery
(O.T. long thoracic)



FIG. 13. The contents of the Axillary Space exposed by the reflection of the
Pectoralis Major and the subjacent fascia, and the removal of the fat and
glands.



emerge between the digitations of the serratus anterior, behind
the inferior border of the pectoralis minor. He must trace them
forwards and backwards respectively, and he may expect to find
communications between the posterior division of the third lateral
branch and the intercosto-brachial nerve. At the junction of the
anterior and medial walls of the axilla and at the lower border



28 THE SUPERIOR EXTREMITY

of the pectoralis minor, find the lateral thoracic artery ; clean the
artery and the medial group of axillary lymph glands, which lie
along its course.

At the junction of the posterior third and anterior two-thirds
of the medial wall of the axilla find the long thoracic nerve, which
supplies the serratus anterior and descends along its lateral
surface, from the apex to the base of the axilla. After the nerve
has been secured the serratus anterior must be cleaned. When
that has been done the dissector should clean the distal parts of
the large vessels and nerves and their branches and tributaries.

With chain and hooks pull the axillary artery and the medial
cutaneous nerve of the forearm towards the arm and displace
the axillary vein in the opposite direction ; then find the ulnar
nerve which lies in the posterior part of the interval between the
artery and vein ; pull the ulnar nerve laterally, and behind the
artery find the large radial nerve (O.T. musculo -spiral). Pull it
medially and follow its lateral border upwards. At the lower
border of the subscapularis muscle on the lateral side of the
radial nerve secure the axillary nerve as it turns backwards into
the posterior wall of the axilla. Near the axillary nerve is the
large subscapular branch of the axillary artery accompanied by
the corresponding vein. The subscapular artery springs from
the medial side of the axillary artery. A short distance below its
origin it divides into two branches, the circumflex scapular and
the thoraco-dorsal. The circumflex scapular passes backwards
into the posterior wall of the axilla. The thoraco-dorsal artery
descends along the lower border of the subscapularis muscle to
the angle where the posterior wall joins the medial wall of the
axilla. Follow the artery downwards, taking care not to injure
the intercosto-brachial nerve and the posterior branches of the
lateral rami of the 3rd, 4th, and 5th intercostal nerves which cross
in front of it. Note the posterior group of axillary lymph glands
which lie along its course, and near its lower end secure the
thoraco-dorsal nerve, which crosses in front of the artery, on its
way to the latissimus dorsi, which it supplies. Return to the
division of the subscapular artery. Dissect in the angle between
its circumflex scapular and its thoraco-dorsal branches and
secure the second subscapular nerve, which supplies the teres
major muscle ; follow it to the muscle.

Return to the radial nerve and find springing from its medial
border near the lower margin of the subscapularis the posterior
brachial cutaneous nerve, and branches to the long and medial
heads of the triceps muscle. Not uncommonly all those branches
are conjoined at their origin, and separate as they pass to their
destinations. The posterior brachial cutaneous nerve, on its
way to the middle of the posterior aspect of the arm, passes
behind the intercosto-brachial nerve. The nerve to the long
head of the triceps enters the proximal part of that muscle.
There are usually two branches to the medial head of the triceps ;
one enters the proximal part of the muscle, and the other, known
as the ulnar collateral, because it runs by the side of the ulnar
nerve, passes to the distal part. It will be traced to its termina-
tion at a later period.

The anterior and posterior humeral circumflex branches of
the axillary artery will be found springing from the artery a
short distance distal to the subscapular branch, the former



AXILLARY SPACE



29



arising from the anterior, and the latter from the posterior aspect
of the axillary trunk.

After the lower part of the axilla has been thoroughly cleaned,
the pectoralis minor must be divided, about midway between its
origin and insertion, and the two parts must be turned aside.
When that has been done the upper subscapular nerve must be
found as it enters the upper part of the subscapularis, and then
the remaining areolar tissue must be removed from the axillary
space, the trunks and branches of the axillary vessels and nerves
must be thoroughly cleaned, and the contents of the space must
be studied in detail.



Right jugular
lymph trunk

Right subclavian

lymph trunk

Right lymph. _

duct

Superior anterior
mediastinal lymph glan "

Thoracic duct




Sternal lymph glands
of right side



Sternal lymph glands of left sid



Inferior deep cervical
lymph glands



Infraclavicular lymph
glands

nterpectoral lymph
gland



Anterior axillary
lymph glands

Central
7 "axillary

lymph glands



ft mamma



Lymph vessels going to join
lymph vessels of abdomen

FIG. 14. Diagram of the Connections of the Lymph Vessels of
the Mamma.



Lymphoglandulae Axillares (Axillary Lymph Glands).

The lymph glands in the axillary region are spoken of,
collectively, as the axillary glands, but for convenience of
description, and to facilitate a more precise knowledge of
their connections and associations, they are subdivided into
several subordinate groups. Some of the glands have been
removed as the dissection proceeded, and others are so small
that they may have escaped the attention of the dissector;
but if he has followed the directions given above he will
have noted at least four groups of glands, (i) A lateral or
brachial group consisting of six or more glands, which lie



30 THE SUPERIOR EXTREMITY

along the axillary vessels. They receive the lymph vessels
from the greater part of the upper extremity, and those at the
upper part of the chain also receive lymph from the deep
part of the mamma. (2) A pectoral group, or anterior group,
which lies in the angle between the anterior and medial walls
of the axilla. This is subdivisible into two parts : (a) an
upper group of two or three small glands which lie behind
the pectoralis major in the region of the second and third
intercostal spaces these receive lymph from the anterior wall
of the thorax and from the lateral two-thirds of the mamma ;
(l>) an inferior group which lies along the posterior border of
the lateral thoracic artery, and receives lymph from the lateral
wall of the thorax. (3) A posterior or subscapular group,
which lies along the subscapular artery on the posterior wall of
the axilla, and receives lymph vessels from the back. (4) The
delto-pectoral glands, a group of two or three small glands
which lie in the delto-pectoral triangle and receive lymph
from the proximal and lateral parts of the arm.

In addition to the lymph glands which are usually seen in
an ordinary dissection, there are three other groups of glands.
(a) Inter-pectoral glands, from one to three or four, which lie
on the anterior surface of the pectoralis minor ; they receive
lymph from the deep part of the mamma by lymph vessels
which pierce the pectoralis major, (b) The central glands,
which are very variable ; they lie either on the surface of the
axillary fascia, in a pocket of its substance, or deep to it
in the fat of the middle part of the axilla ; they have no
afferents from any definite region, but are connected with
the other groups, (c) The infraclavicular glands, which lie
in the apex of the axilla behind the costo-coracoid membrane.
They receive efferents from all the lower groups, and their
efferents unite to form a subclavian lymph trunk which
terminates on the left side in the thoracic duct, and on the
right side in the right lymph duct (Fig. 14).

Kami Laterales (O.T. Lateral Cutaneous Branches) of the
Anterior Branches of the Second and Third Thoracic Nerves.
As a rule, the first thoracic nerve does not give off a lateral
branch. That which springs from the second thoracic nerve
is the largest of the series, and differs from the others in not
dividing into an anterior and a posterior branch. It is termed
the intercosto-brachial nerve, on account of its being distributed
to the skin on the medial and dorsal aspects of the proximal



AXILLARY SPACE



part of the arm. To reach this destination it crosses the
axilla and pierces the deep fascia. But before piercing the
fascia it establishes communications and forms a plexiform
arrangement in the axilla with the medial cutaneous nerve of
the arm, and the lateral branch of the third thoracic nerve.
The plexus so formed may be joined by another twig which



Acromial branch of thoraco-acromial artery

r y T ,



Thoraco-acromial artery

Clavicular branch of
thoraco-acromial artery



Deltoid branch of thoraco-acromial artery
Axillary artery
| Anterior humeral circumflex artery



Coracoid process
cromial
Axillary arte



Posterior humeral
circumflex artery
Subscapular artery

Circumflex scapular artery



Subclavius muscler'



Supreme thoracic
artery-
Pectoral branch of.
thoraco-acromia
artery




'Thoraco-dorsal artery
Serratus anterior
Lateral thoracic artery



FIG. 15. Dissection of the Axillary Artery and its Branches.

is occasionally present, viz., the minute lateral cutaneous
branch of the first thoracic nerve.

The lateral branch of the third thoracic nerve divides into
an anterior and posterior part, which are distributed in the
ordinary way. From the posterior branch twigs are given to
the skin of the axilla, and the terminal twigs are distributed
to the integument on the proximal part of the medial aspect
of the arm.

Arteria Axillaris. The axillary artery is the chief artery



32 THE SUPERIOR EXTREMITY

of the upper limb. It enters the axilla at its apex, at the
outer border of the first rib, commencing as the continua-
tion of the subclavian artery. It lies, for a short distance,

Posterior circumflex artery Anterior circumflex artery



Subscapular artery
Musculo-cutaneous nerve
Axillary nerve (O.T. circumflex)

Cephalic vein
Acrpmial artery
Lateral anterior thoracic nerve
Lateral cord of brachial plexus
Thoraco-acromial artery -.
Axillary artery, ist pai t

Axillary vi
Subclavius muscle



Pectoralis major

Coraco-brachialis
Biceps brachii
(short head)



Medial anterior
thoracic nerve

Pectoral branch

of thoraco-

acromial aitery




i ; Basilic vein
' Brachial artery
Median nerve



Fascial band connecting lat.
Jj^ 1 dorsi with long head of triceps

i Medial cutaneous nerve of the

! forearm
Ulnar nerve



Medial cutaneous nerve of the arm
( Teres major
Radial nerve (O.T musculo-spiral)

Circumflex artery of scapula (O.T.
Y\ ' dorsalis scapula:)
1 Lower subscapular nerve

! Subscapularis muscle

f I Posterior division of a lateral cutaneous nerve

Latissimus dorsi
Thoraco-dorsal nerve (O.T. middle subscapular)



' Anterior branch of a
lateral cutansous nerve



Long thoracic nerve
intercosto-brachial nerve
Lateral thoracic artery
(O.T. long thoracic)



FiG. 16. The contents of the Axillary Space exposed by the reflection of the
Pectoralis Major and the subjacent fascia, and the removal of the fat an
the lymph glands. Part of the axillary vein has been removed to expose
the medial cutaneous nerve of the forearm and the ulnar nerve.



on the medial wall of the axilla, crosses the fat in the angle
between the medial and posterior walls, and then runs along
the lateral wall to the lower border of the teres major ; there it



AXILLARY SPACE 33

leaves the axilla and passes into the arm, where it becomes the
brachial artery. For convenience of description it is usually
divided into three parts the part above, the part behind, and
the part below the pectoralis minor, which are known
respectively as the first, second, and third parts. The
direction which the art'ery takes varies with the position of
the limb. When the arm is at a right angle with the body,
the direction is that of a straight line from the centre of the
clavicle to the middle of the bend of the elbow. When the
arm is by the side, the artery describes a curve with the
convexity directed laterally; and if the arm is raised above
the head the curve formed by the artery is convex in the
reverse direction.

The first part of the axillary artery lies very deeply. It is
covered, anteriorly, by the skin, superficial fascia, deep fascia,
the clavicular part of the pectoralis major, the costo-coracoid
membrane, and the vessels and nerves superficial to it. Even
when those are removed the vessel is not completely exposed,
because it is enveloped, along with the axillary vein and great
nerves, by a funnel-shaped sheath, which is prolonged upon
them from the deep cervical fascia (Fig. 12), and it is
crossed by the loop of communication between the two
anterior thoracic nerves which lies in front of the sheath.
Behind this part of the vessel are the first intercostal space
and the first digitation of the serratus anterior muscle; the
long thoracic nerve and the medial cord of the brachial
plexus also cross behind it. To its medial side, and some-
what overlapping it, is the axillary vein, whilst above and to
its lateral side are the lateral and posterior cords of the
brachial plexus.

The second part of the axillary artery is placed behind
the two pectoral muscles, and has the three cords of the
brachial plexus disposed around it. The medial cord lies
upon its medial side, the lateral cord upon its lateral side,
and the posterior cord behind it. The axillary vein is still
upon its medial side, but is separated from the artery by the
medial nerve-cord. Strictly speaking, it is not in apposition
with any muscle posteriorly, being separated from the sub-
scapularis muscle by areolo-fatty tissue.

The third and longest part of the axillary artery is superficial
in its distal half, because the anterior wall of the axilla does
not extend so far down as the posterior wall. Therefore,
VOL. i 3



34



THE SUPERIOR EXTREMITY



whilst the third part of the axillary artery is covered, in its
proximal half, by the pectoralis major, its distal half is covered
only by the skin and fasciae. Behind it, proximo-distally, are
the subscapularis, the tendon of the latissimus dorsi, and
the teres major; but it is separated from the subscapularis
muscle by the axillary (O.T. circumflex) and radial (O.T.
musculo-spiral) nerves, and from the latissimus dorsi and the
teres major by the radial nerve. To its lateral side is the




Lateral cord

Posterior cord lofbrachial plexus
: Medial cord J



I



. Musculo-cutaneous nerve
Median nerve (lateral head)
Median nerve (medial head)
Medial cutaneous nerve of the forearm
Medial cutaneous nerve of the arm



Median nerve



Ulnar nerve
Radial nerve (O.T. musculo-spiral)
FIG. 17. Diagram to show relations of Axillary Vessels and Nerves.

coraco-brachialis muscle, but between the muscle and the artery
are the musculo-cutaneous and the median nerves. To the
medial side of the artery is the vein, with the medial
cutaneous nerve of the forearm in the anterior angle between
the artery and vein, and the ulnar nerve in the posterior angle
between the artery and vein. The medial cutaneous nerve
of the arm lies along the medial side of the vein (Fig. 17).

The branches of the axillary artery have been seen at
different stages of the dissection. They should now be ex-
amined more fully (Fig. 15). They are:



AXILLARY SPACE 35



A. thoracalis suprema \from the

J first part.

A. thoraco-acromialis"\ from the

A. thoracalis lateralis/ second part.



A. subscapularis . *j

A. circumflexa I f

humeri anterior I the
A. circumflexa third P art "



humeri posterior






Arteria Thoracalis Suprema (O.T. Superior Thoracic).

The supreme thoracic artery is a small branch which springs
from the axillary at the lower border of the subclavius. It
ramifies upon the upper part of the medial wall of the axilla
and supplies twigs to adjacent structures (Fig. 15).

Art. Thoraco-acromialis (O.T. Acromio-thoracic or Thoracic
Axis). The thoraco-acromial artery is a short, wide trunk,
which takes origin under cover of the pectoralis minor. It
winds round the upper border of that muscle, pierces the costo-
coracoid membrane, and immediately divides into branches ;
the branches receive different names, and are arranged as
follows : (a) The clavicular branch, a small twig, which runs
upwards to the clavicle and then turns medially along that
bone, between the clavicular part of the pectoralis major and
the costo-coracoid membrane, (b) The pectoral branches, of
larger size, run downwards between the two pectoral muscles ;
they give branches to both muscles, and they anastomose with
the lateral thoracic and the lateral branches of the intercostal
arteries, (c] The acromial branch runs laterally, upon the
tendon of the pectoralis minor and the coracoid process.
Some of its twigs supply the deltoid, whilst others pierce it to
reach the superior surface of the acromion. It anastomoses
with the transverse scapular (O.T. suprascapular) and posterior
humeral circumflex arteries. (d) The deltoid branch, as a
rule, takes origin from a trunk common to it and the pre-
ceding artery. It runs distally in the intermuscular interval
between the pectoralis major and the deltoid, and supplies
both muscles.

Arteria Thoracalis Lateralis. The lateral thoracic artery
takes the lower border of the pectoralis minor as its guide,
and proceeds downwards and medially to the side of the
thorax. It gives branches to the neighbouring muscles.
It anastomoses with twigs from the intercostal arteries,
and it also supplies the mamma, giving off, as a rule, an
external mammary branch, which winds round or pierces
the lower border of the pectoralis major on its way to the
gland.



36 THE SUPERIOR EXTREMITY

Alar Thoracic. This small artery supplies the fat and lymph glands
in the axilla, but it is rarely present as a separate branch, and its place is
usually taken by twigs from the subscapular and lateral thoracic arteries.

Arteria Subscapularis. The subscapular branch of the
axillary is a relatively large and comparatively short branch
which springs from the parent trunk at the lower border of
the subscapularis muscle. It descends, for about one inch,
along the lower border of the subscapularis, and then divides



Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 5 of 44)