D. J. (Daniel John) Cunningham.

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clean the circumflex scapular artery, and study the transverse
ligaments of the scapula and the arterial anastomosis round the
scapula.

Ligamenta Transversa Scapulae. There are two transverse
scapular ligaments (i) a superior, tigamcntum transversum
scapula superius', (2) an inferior, Ugamentum transversum scapulce
inferius (O.T. spino-glenoid). Both the transverse ligaments
are associated with the transverse scapular vessels and the
suprascapular nerve. The superior transverse ligament
bridges across the notch in the superior border of the scapula
and converts it into a foramen. It lies between the transverse
scapular artery, which passes above it, and the suprascapular
nerve, which lies in the notch below it. In not a few cases it
is ossified. The inferior transverse ligament is a weaker band
which bridges across the great scapular notch at the back of
the neck of the scapula, passing from the lateral border of the
spine of the scapula to the posterior margin of the glenoid
cavity. The infraspinous branch of the transverse scapular
artery and the suprascapular nerve lie in the notch, deep to
the ligament.



90 THE SUPERIOR EXTREMITY

Dissection. Revise the arteries which lie in relation with
the borders and surfaces of the scapula, and dissect out the
anastomosis between their branches. Descending along the
vertebral border is the descending branch of the transverse
cervical artery. Crossing the superior border is the supra-
scapular artery. The subscapular artery was seen during the
dissection of the axilla ; it springs from the third part of the
axillary, descends for about 25-30 mm. along the inferior border
of the subscapularis, and then divides into circumflex scapular
and thoraco -dorsal branches. The circumflex scapular at once
turns round the axillary border of the scapula and passes, deep
to the teres minor, to the infraspinous fossa. Follow the rami-
fications of both branches to their anastomoses with the adjacent
arteries.

The Anastomosis around the Scapula. An important and
free anastomosis takes place between the branches of three
arteries which lie in close relation with the scapula, viz. : (i)
the descending branch of the transverse cervical artery ; (2)
the transverse scapular artery ; (3) the circumflex scapulae and
thoraco-dorsal branches of the subscapular artery.

The Descending Branch of the Transverse Cervical
Artery was seen when the levator scapulae and the rhomboids
were reflected. It runs downwards along the vertebral border
of the scapula in the angle between the levator scapulae and
the rhomboids, which are behind it, and the insertion of the
serratus anterior, which is in front of it. It sends branches
into the subscapular fossa and into the supra- and infraspinous
fossae, which anastomose in all three regions with branches of
the transverse scapular and subscapular arteries, and at the
inferior angle of the scapula it anastomoses with the terminal
branches of the thoraco - dorsal branch of the subscapular
artery.

Arteria Transversa Scapulae (O.T. Suprascapular Artery).
The transverse scapular artery enters the supraspinous
fossa by passing over the ligament which bridges across the
scapular notch. It divides, under cover of the supraspinatus
muscle, into a supraspinous and an infraspinous branch. The
former supplies the supraspinatus muscle, and gives off the
chief nutrient artery to the scapula ; the latter proceeds down-
wards through the great scapular notch, under cover of the
inferior transverse scapular ligament, to reach the deep surface
of the infraspinatus muscle, to which it is distributed.

At the superior border of the scapula the transverse artery
of the scapula gives off a subscapular branch, which enters the
subscapular fossa, under cover of the subscapularis muscle.



SHOULDER SCAPULAR REGION 91

Arteria Circumflexa Scapulae (O.T. Dorsalis Scapulae

Artery). The circumflex scapular artery, as already noted,
arises from the subscapular branch of the axillary and enters
the triangular space. While there it supplies one or two
ventral branches, which pass, under cover of the subscapular
muscle, to the subscapular fossa, and a larger infrascapular
branch, which runs downwards, in the interval between the teres
major and teres minor, to the inferior angle of the scapula
(Figs. 34, 35, pp. 79, 80). After those branches are given
off, the circumflex scapular artery leaves the triangular space
by turning round the axillary border of the scapula, under
cover of the teres minor. It now enters the infraspinous
fossa, where it ramifies, and supplies branches to the infra-
spinatus muscle.

Arteria Thoracodorsalis. The thoraco-dorsal branch of
the subscapular artery runs along the axillary border of the
scapula on the lower margin of the subscapularis. It sends
branches into the subscapular fossa which supply the sub-
scapularis and anastomose with branches of the descending
branch of the transverse cervical artery, and the transverse
scapular and circumflex scapulte arteries.

When the dissector has followed the branches of the four
arteries just considered, he will realise that the arterial
anastomosis around the scapula is very complete. In the
supraspinous fossa branches of the descending branch of the
transverse cervical artery and the transverse scapular artery
anastomose. In the infraspinous fossa branches of the
descending branch of the transverse cervical, the transverse
scapular, and the subscapular artery anastomose, and branches
of the same three arteries anastomose in the subscapular
fossa. The importance of these free communications is
manifest when it is remembered that two of the main arteries,
viz., the descending branch of the transverse cervical artery
and the transverse artery of the scapula, spring indirectly from
the first part of the subclavian ; whilst the third, viz., the
subscapular, arises from the third part of the axillary. When,
therefore, a ligature is applied to any part of the great arterial
trunk of the upper limb, between the first stage of the sub-
clavian and the third part of the axillary, the anastomosis
round the scapula affords ample means of re-establishing the
circulation.

Nervus Suprascapularis. The suprascapular nerve



92 THE SUPERIOR EXTREMITY

accompanies the transverse artery of the scapula, but it
enters the supraspinous fossa by passing through the scapular
notch, under cover of the upper transverse ligament of the
scapula. It supplies the supraspinatus, and ends in the infra-
spinatus muscle. It usually sends two articular twigs to the
posterior aspect of the shoulder-joint, viz., one while in the
supraspinous fossa and the second as it lies in the infra-
spinous fossa.

The ligaments which connect the clavicle with the scapula
should now be examined; they are (i) the coraco-clavicular
ligament, which is found between the clavicle and the coracoid
process of the scapula and the capsule of the acromio-
clavicular joint.

Dissection. Clean the surfaces and borders of the coraco-
clavicular ligament, and note that it consists of two segments
a medial segment called the conoid ligament and a lateral
segment called the trapezoid ligament. The two segments
meet at an angle which is open in front, and in the angle a small
bursa is sometimes found. After the coraco-clavicular ligament
has been fully defined, remove the remains of the deltoid and
trapezius muscles from the capsule of the acromio-clavicular
joint and clean the external surface of the capsule.

Lig. Coracoclaviculare. The coraco - clavicular ligament
is a powerful ligament which binds the inferior surface of the
clavicle to the coracoid process. It consists of two parts,
which are termed the conoid and the trapezoid ligaments.

The ligamentum conoideum lies posterior and medial to
the lig. trapezoideum. It is broad above, where it is attached
to the coracoid tubercle of the clavicle (Fig. 10, p. 21), and
somewhat narrower below, at its attachment to the bend of
the coracoid process. The ligamentum trapezoideum is a
flatter band. Above, it is attached along the trapezoid line
of the clavicle (Fig. 10, p. 21), whilst below it is fixed to the
upper aspect of the coracoid process.

The coraco-clavicular ligament helps to prevent dislocation
of the acromial end of the clavicle, and, to a certain extent,
it limits the movements of the acromio-clavicular joint. It
is therefore an accessory ligament of that joint. It is the
main medium by which the scapula, and, indirectly, the other
parts of the superior extremity, are suspended from the
clavicle. If it is cut when the body is erect, the superior
extremity as a whole at once falls, and the same thing occurs



SHOULDER SCAPULAR REGION 93

if the clavicle is broken medial to the attachment of the
ligament.

Articulatio Acromio-Clavicularis. The acromio-clavicular
joint is a diarthrodial joint ; and the ligaments which bind
the bones together at the joint are :

Articular Capsule :

Superior acromio-clavicular ligament.

Inferior acromio-clavicular ligament.
Accessory Ligament, not connected with the capsule :

Coraco-clavicular.

The superior and inferior acromio-clavicular ligaments are
simply thickened parts of the fibrous stratum of the articular
capsule.

The superior acromio-clavicular ligament is a broad band,
composed of stout fibres, which is placed on the upper
aspect of the joint. The inferior acromio-clavicular ligament,
which closes the joint below, is not so strongly developed.
In front and behind, the two ligaments are connected with
each other so as to constitute a capsule. The joint should
now be opened to display the synovial stratum of the capsule
and an imperfect articular disc which is usually present. The
disc is wedge-shaped, and connected by its base to the
superior ligament, whilst its free margin is directed downwards
between the bones.

The two surfaces of the joint are flat and are ovoid in
outline, and each slopes obliquely downwards and medially.
There is therefore a tendency for the clavicle to glide, upwards
and laterally, on to the upper surface of the acromion. The
tendency is counteracted by the strength of the superior
acromio-clavicular ligament.



THE FRONT OF THE ARM.

In the anterior region of the arm the following structures
have to be studied :

Cutaneous veins.

Cutaneous nerves of the arm.

Parts of the cutaneous nerves of the forearm.

The brachial fascia.



94 THE SUPERIOR EXTREMITY

The brachial artery and its branches.

The median, ulnar, radial and musculo-cutaneous nerves.

The biceps, coraco-brachialis and brachialis muscles.

It is convenient to study at the same time the cubital
fossa in front of the elbow.

The skin has already been removed, and the cutaneous
veins and nerves have been seen (see pp. 62, 63). Now they
must be re-studied, and the main points of the surface anatomy
of the region must be revised.

Surface Anatomy. In a muscular limb the prominence
formed by the biceps muscle along the front of the arm is
very apparent. Every one is familiar with the rounded swelling
which the muscle produces when powerfully contracted in the
living subject. On each side of the biceps there is a feebly
marked furrow, and ascending in each of these there is a
large superficial vein. In the lateral sulcus is the cephalic
vein ; in the distal part of the medial sulcus is the basilic vein.
In the proximal part of the medial bicipital sulcus is an
elongated bulging produced by the subjacent coraco-brachialis
muscle ; it is useful as a guide to the distal part of the
axillary and the proximal part of the brachial arteries, which
lie immediately behind and to the medial side of it. The
humerus is thickly clothed by muscles ; but towards its distal
part the two epicondylar ridges, leading to the epicondylar
eminences, may be felt. The lateral ridge is the more
salient of the two, and therefore the more evident to
touch.

The bony points around the elbow must be studied with
especial care. It is by a proper knowledge of the normal
relative positions of them that the surgeon is able to dis-
tinguish between the different forms of fracture and dis-
location which so frequently occur in the elbow region. First
note the medial epicondyle of the humerus. It constitutes
a prominence appreciable to the eye ; grasp it between the
finger and thumb, and note that it inclines posteriorly as
well as medially. In a well-developed, fully extended arm,
the lateral epicondyle does not form a projection on the
surface, but can be felt at the bottom of a slight depression
on the dorsal aspect of the limb. It becomes apparent to
the eye as a prominence when the elbow is semi-flexed. The
olecranon produces a marked projection on the dorsum of
the elbow between the two epicondyles. It is placed slightly



THE FRONT OF THE ARM



95



nearer to the medial than to the lateral epicondyle. The
loose skin which covers the olecranon moves freely over its
subcutaneous surface, owing to the interposition of a bursa.
The different positions which are assumed by the olecranon,
in relation to the epicondyles of the humerus in the move-
ments of the forearm at the elbow-joint, must be carefully
examined. That can be done best by placing the thumb on
one epicondyle, the middle finger on the other, and the fore-




FIG. 39. Relation of Bones
of Elbow to the surface.
Dorsal view ; elbow fully
extended.




FIG. 40. Relation of the
Bones of the Elbow to the
surface. Dorsal view ;
elbow bent.



finger on the olecranon. The limb should then be alternately
flexed and extended, so as to make clear the extent of the
excursion performed by the olecranon. In full extension
at the elbow -joint the three prominences lie in the same
horizontal plane ; when the forearm is bent at a right angle
the three bony points are placed at the angles of an equilateral
triangle, of which one angle points distally.

When the forearm is extended a marked depression on the
dorsal aspect of the elbow indicates the position of the articula-



96 THE SUPERIOR EXTREMITY

tion between the radius and the humerus. Immediately distal
to it the head of the radius lies near to the surface, and can
readily be felt, especially when it is made to roll under the
finger by inducing alternately the movements of pronation
and supination. The head of the radius is placed about
25 mm. (one inch) distal to the lateral epicondyle.

Venae Superficiales. Portions of two large cutaneous
veins are met with in the arm, the cephalic vein and the
basilic vein. They were dissected and studied when the
cutaneous nerves of the superior extremity were examined
(see p. 63). Their positions in the arm should now be
revised. Both ascend from the back of the hand, and they
communicate with one another across the fascial roof of the
cubital fossa at the front of the elbow, by means of the
median cubital vein.

In the arm the cephalic vein ascends along the groove at
the lateral border of the biceps or along the lateral part of
the eminence caused by the biceps muscle, to the delto-
pectoral sulcus. There it pierces the deep fascia, and it
continues upwards to the delto- pectoral triangle where it
turns medially, crosses superficial to the pectoralis minor,
pierces the costo-coracoid membrane, under cover of the
pectoralis major, and terminates in the axillary vein.

The portion of the basilic vein which lies in the arm
ascends in the groove along the medial border of the biceps
muscle. At the middle of the arm it pierces the deep fascia,
and runs along the medial side of the brachial artery to the
axilla, where it becomes the axillary vein.

Nervi Cutanei. The cutaneous nerves found in the
region of the arm at a previous stage of the dissection were :

Nn. supraclaviculares (the posterior group) from the

cervical plexus.

N. cutaneus brachii lateralis from the axillary nerve.
N. intercosto-brachialis from the second intercostal

nerve.

N. cutaneus brachii medialis from the brachial plexus.
N. cutaneus antibrachii medialis from the brachial plexus.
N. cutaneus brachii posterior from the radial nerve.
N. cutaneus antibrachii dorsalis from the radial nerve.
N. cutaneus antibrachii lateralis from the musculo-

cutaneous nerve.



THE FRONT OF THE ARM 97

All these nerves have already been studied (p. 69) ;
the supraclavicular nerves were removed, and the lateral
brachial cutaneous nerve was displaced when the shoulder
region was examined. Their general positions and distribu-
tion of the remaining nerves should now be revised.

The intercosto - brachial nerve supplies the skin of the
posterior part of the medial aspect of the arm and the
adjacent part of the back of the arm from the axilla to
the elbow (Figs. 31, 32).

The medial cutaneous nerve of the arm pierces the deep fascia
at the middle of the arm, on the medial side, and supplies
the skin of the distal half of the medial aspect of the arm.
Before it pierces the fascia it gives off no branches of
distribution, but it may communicate with the intercosto-
brachial nerve (Figs. 31, 16).

The medial cutaneous nerve of the forearm pierces the deep
fascia at the middle of the arm, on the medial side, some-
times passing through the opening which admits the basilic
vein. Before it becomes superficial it gives off several
branches which pierce the deep fascia at varying points
from the axilla to the middle of the arm ; those branches,
together with others given off after the nerve pierces the
deep fascia, supply the skin on the medial part of the
anterior aspect and the anterior part of the medial aspect
of the arm, from the axilla to the elbow. The two terminal
branches of the nerve, volar and ulnar, supply the skin of
the medial part of the volar aspect, and the ulnar border
of the forearm as far as the wrist. As the volar branch
leaves the arm it usually passes between the median
cubital vein and the lacertus fibrosus. The ulnar branch
descends either in front of or behind the medial epicondyle
(Figs. 31, 32).

The posterior brachial cutaneous nerve supplies the skin
of the middle of the back of the arm from the axilla to
the elbow.

The dorsal cutaneous nerve of the forearm usually pierces
the deep fascia in two parts, a short distance distal to the
insertion of the deltoid. The proximal branch supplies
some twigs to the lateral part of the back of the arm, and
then turns forwards to supply the skin of the lateral part
of the front of the arm, from the level of the insertion of
the deltoid to the elbow. The distal branch supplies twigs

VOL. i 7



98 THE SUPERIOR EXTREMITY

to the distal part of the arm, both on the anterior and
posterior aspects, and then descends to supply the skin
of the middle of the back of the forearm as far as the
wrist (Figs. 31, 32).

The lateral cutaneous nerve of the forearm pierces the deep
fascia proximal to the elbow, passes deep to the cephalic
vein, and supplies the skin on the lateral parts of the volar
and dorsal aspects of the forearm as far as the wrist. It
also supplies the skin of the proximal part of the thenar
eminence (Figs. 31, 32).

Fascia Brachii. After the cutaneous nerves have been
revised re-examine the deep fascia of the arm. Note (i)
that it consists largely of transverse fibres ; (2) its close
attachment to the bony prominences at the elbow and
to the distal parts of the medial and lateral borders
of the humerus ; (3) its connection with the muscles
which spring from the medial and lateral epicondyles of the
humerus ; (4) the thickened band of fibres called the lacertus
fibrosus which passes from the distal part of the medial
border of the biceps to the medial side of the proximal
part of the forearm (Figs. 31, 61). It is also connected
with the tendons of insertion of the deltoid, the pectoralis
major and the latissimus dorsi, but those connections were
severed when the muscles were cleaned.

Dissection. (i) Cut through the deep fascia along the
proximal and distal borders of the lacertus fibrosus, from the
medial margin of the biceps to the medial margin of the fore-
arm, and leave the lacertus fibrosus in position when the re-
mainder of the deep fascia is reflected. (2) Make a longitudinal
incision through the deep fascia along the middle line of the
biceps. (3) At the level of the epicondyles make a transverse
incision through each of the flaps marked out by the longitudinal
incision, and (4) reflect each of the two flaps to its own side.
As the reflection proceeds it will become evident that septa pass
from the deep surface of the deep fascia between the various
muscles. Thus a septum passes transversely from side to side
between the biceps and brachialis muscles (Figs. 42, 43). In it
is embedded the musculo-cutaneous nerve. A septum dips back-
wards between the brachialis and the muscles which spring from
the anterior lip of the distal half of the lateral border of the
humerus. The radial nerve and anterior branch of the pro-
funda artery are embedded in it (Fig. 42), but the strongest
and most important septa are the lateral and medial inter-
muscular septa which separate the structures at the back of the
arm from those at the front. Each is attached to the whole
length of the corresponding border of the body of the humerus,
but the distal halves are the strongest parts. The medial inter-



THE FRONT OF THE ARM



99



muscular septum is stronger than the lateral. It is easily traced
from the medial epicondyle to the insertion of the coraco-
brachialis muscle. The distal half of the lateral intermuscular
septum is quite definite from the lateral epicondyle to the inser-
tion of the deltoid muscle. The two septa, together with the
humerus, divide the arm into an anterior and a posterior osteo-
fascial compartment.

Structures in the Anterior Compartment. The anterior
osteo-fascial compartment has been opened by the reflection
of the anterior part of the deep fascia ; the relative positions
of its contents must now be examined. The contents are :
Three muscles which belong mainly to the arm, the biceps,



Medial inter-
muscular septum




Lateral inter-
muscular septum



FIG. 41. Diagram (after Turner) to show how the Arm
is divided by the intermuscular septa and the bone into an
anterior and a posterior compartment. These compartments
are represented in transverse section.

the coraco - brachialis, and the brachialis ; parts of two
muscles which belong chiefly to the forearm the brachio-
radialis and the extensor carpi radialis longus ; parts of the
terminal branches of all the cords of the brachial plexus
except the axillary nerve ; the brachial artery, its venae
comites, part of the basilic vein, with accompanying lymph
vessels and a few small brachial lymph glands which lie
along the course of the brachial artery.

The biceps brachii is the most anterior muscle ; under
cover of its distal half and closely applied to the anterior
aspect of the humerus is the brachialis, whilst the slender
coraco-brachialis lies along the medial side of the proximal
half of the biceps. The brachio-radialis and the extensor

i 7 a



ioo THE SUPERIOR EXTREMITY

carpi radialis longus lie in the distal part of the compartment
along the lateral side of the brachialis, to which they are
closely applied. The brachial artery and its venae comites
traverse the whole length of the compartment in relation
with the medial border of the biceps. The median nerve
also runs through the whole length of the compartment
lying, in the proximal half, lateral to the brachial artery, and
in the distal half, medial to it. The basilic vein enters the
compartment at the middle of the arm, where it pierces the
deep fascia, and then ascends along the medial side of the
brachial artery.

Dissection. If the piece of wood, to which the axillary artery
and the nerves were previously fixed, has been detached from the
coracoid process, retie it to that process and proceed to clean the
brachial artery and its branches, its venae comites, the deep
proximal part of the basilic vein, and the accompanying nerves.
It is important that the artery should be disturbed as little as
possible before its relations are studied. Therefore commence
the dissection by cleaning the nerves and the veins, and take
care not to injure the branches of the artery. Begin with the
medial cutaneous nerve of the arm, trace it along the medial
side of the basilic vein and through the opening in the deep fascia
to its termination. As a rule it gives off no branches of dis-
tribution before it pierces the deep fascia, but it communicates
with the intercosto-brachial nerve (Fig. 16). Next follow the



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