D. J. (Daniel John) Cunningham.

Cunningham's manual of practical anatomy (Volume 1) online

. (page 8 of 44)
Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 8 of 44)
Font size
QR-code for this ebook


Nervus Dorsalis Scapulae (O.T. Nerve to the Rhomboids).

This long slender nerve arises, in the neck, from the fifth
cervical nerve, usually in common with the upper root of
the long thoracic nerve. It pierces the scalenus medius,
and passes downwards, under cover of the levator scapulae,
to the deep surface of the rhomboidei muscles. It ends in
those muscles, but it supplies, also, one or two twigs to the
levator scapulae.

The root twigs of origin of the dorsalis scapulae nerve
sometimes pierce the levator scapulae separately, and then
unite in a plexiform manner.

Ramus Descendens of the Art. Transversa Colli (O.T.
Posterior Scapular Artery). The descending branch of the
transverse cervical artery takes origin in the lower part of
the neck close to the lateral margin of the levator scapulae.
At first it runs medially .under cover of the levator scapulae,
but it soon changes its direction and then runs downwards
along the vertebral border of the scapula, under cover of the
rhomboid muscles (Fig. 26, p. 52). It gives numerous branches
to both the costal and dorsal aspects of the scapula, and its
terminal twigs may enter the latissimus dorsi. One large
branch usually passes backwards, in the interval between the
rhomboid muscles or through the greater rhomboid, to reach
the trapezius muscle ; and another branch, the supraspinal,
is given to the supraspinatus muscle and the structures
superficial to it.

Dissection. Reflection of the Latissimus Dorsi and the
removal of the Superior Extremity. Divide the latissimus dorsi.
Commence the division at the upper border three inches from the
vertebral spine, and carry the knife obliquely downwards and
laterally to a point just below where the last digitation of the
muscle springs from the last rib. Remember that the muscle is
thin, and do not injure the parts subjacent to it. Turn the
medial portion towards the vertebral spines, taking care not to
injure the serratus posterior inferior in the region of the lower
four ribs, and verify the origin of the muscle from the spines
and supraspinous ligaments, lumbar fascia and iliac crest.
Throw the lateral part of the muscle laterally and forwards,
clean the deep surfaces of the slips attached to the lower three
or four ribs, and note that they interdigitate with the ex-
ternal oblique muscle of the abdomen. At the inferior angle
of the scapula find the thoraco-dorsal nerve and the thoraco-
dorsal artery. They supply the muscle and enter its deep
surface.

The Removal of the Superior Extremity. (i) Divide the
transverse scapular artery and the suprascapular nerve and the



62 THE SUPERIOR EXTREMITY

posterior belly of the omo-hyoid at the upper border of the
scapula.

(2) Divide the dorsal scapular nerve and the descending
branch of the transverse cervical artery near the medial angle of
the scapula.

(3) Pull the vertebral border of the scapula away from the
ribs to expose the posterior part of the serratus anterior on the
costal surface of the scapula.

(4) Cut through the posterior part of the serratus anterior from
its upper to its lower border about one inch from the vertebral
margin of the scapula.

(5) Pull the scapula still further away from the thorax and
divide the axillary vessels and nerves at the outer border of the
first rib.

(6) Detach the anterior skin flap previously stitched to the
anterior wall of the thorax, and take the limb to the table
provided, where the further dissection is to be completed.

Tie the divided axillary vessels and nerves to a piece of wood,
about 37.5 mm. (i inches) long, in their proper order (a piece of
a broken penholder will serve the purpose), and then by means
of a loop fix the wood to the coracoid process ; by that means
the vessels and nerves will be retained in their proper relation-
ships during the further stages of dissection, and they can be
released from the coracpid process when it is necessary to
examine anything which lies behind them.

After the superior extremity has been separated proceed to
remove the whole of the skin which covers it whilst the sub-
cutaneous tissues are still in good condition, and in order that a
?eneral view of the cutaneous veins and nerves may be obtained,
he main cutaneous veins carry blood to the axillary vein, and
the cutaneous nerves are either direct branches of the brachial
plexus or they spring from the main terminal branches of the
plexus. The following steps must be taken : (i) place the limb
on its posterior aspect ; (2) make an incision along the anterior
aspect from the region already denuded to the tip of the middle
finger (Fig. 5) ; (3) make a transverse incision at the wrist ;

(4) -a transverse incision at the proximal ends of the fingers ;

(5) an oblique incision from the middle of wrist to the tip
of the thumb; (6) incisions along the middle of the index,
the ring, and the little finger. Turn the lateral flaps 3 and 5
(Fig. 5) laterally, the medial flaps 4 and 6 medially round the
respective margins of the limb, and then dissect them from the
dorsal aspect. Treat the flaps 5 and 7 and those of the fingers
in the same way, and dissect flap 6 distally to the angle between
the thumb and the index finger.

Take great care whilst removing the flaps not to injure the
cutaneous vessels and nerves which lie in the superficial fascia
immediately subjacent to the skin.

Note that the skin is readily separated from the superficial
fascia in the arm and forearm and on the dorsal aspect of the
hand. It is slightly more adherent over the epicondyles of the
humerus and the olecranon. In the regions of the palm and the
volar aspects of the digits, the skin and superficial fascia are
closely adherent, for there the skin is bound to the deep fascia
by fibrous strands which pass through the superficial fascia. In
the ulnar part of the palm, about 25 mm. distal to the wrist,



DISSECTION OF SUPERFICIAL STRUCTURES 63

some muscle fibres will be brought into view ; they connect the
skin on the ulnar margin of the palm with the deep fascia,
and constitute the palmaris brevis muscle.

When the skin is completely removed it must not be thrown
away but must be kept to be wrapped round the part where the
dissection is not proceeding.

Cutaneous Veins of the Superior Extremity. After the skin
has been removed proceed to display the cutaneous veins, because
they are, except here and there, the most superficial structures,
but be careful to preserve any nerves met with as the veins are
being cleaned (Figs. 31, 32).

Commence at the interval between the pectoralis major and
the deltoid and follow the cephalic vein distally, being careful to
preserve the tributaries which join it. At the bend of the elbow
secure a large communicating branch called the median cubital
vein ; it runs obliquely, proximally, and medially, and joins the
basilic vein, about 30 mm. proximal to the level of the medial
epicondyle. The median cubital vein is joined at its distal
border by a vein which pierces the deep fascia and connects the
median cubital vein with the deep veins of the forearm. After
the median cubital vein and its connections have been displayed,
follow the cephalic vein distally, along the forearm and round its
radial margin, to the dorsum of the hand where it commences,
dorsal to the first metacarpal bone, in the radial extremity of the
dorsal venous arch. The dorsal venous arch crosses the dorsum
of the hand, from the radial to the ulnar side, and at its ulnar
end, which lies opposite the interspace between the fourth and
fifth metacarpal bones, the basilic vein commences. Follow
the basilic vein proximally. It passes at first along the dorsal
aspect of the ulnar border of the forearm, then turns round the
ulnar border to the front, and ascends to the arm, where it is
joined by the median cubital vein already dissected. Follow the
basilic vein proximally beyond its junction with the median
cubital vein to the middle of the arm where it pierces the
deep fascia, at the level of the insertion of the coraco-brachialis
muscle. As you clean it, in the lower part of the arm, look for
some superficial cubital lymph glands which lie in the superficial
fascia ; a little proximal to the elbow they receive lymph from the
fingers, palm, and the anterior aspect of the forearm, and are apt
to become inflamed and painful when wounds of those parts
become septic. The cephalic and the basilic veins receive tribu-
taries, which vary in number and size, both from the dorsal and
the volar surfaces of the forearm and hand.

When the cephalic and basilic veins and their main tributaries
have been cleaned, return to the dorsum of the hand, clean the
dorsal venous arch and the tributaries which pass to it from the
digits ; they are (i) three dorsal metacarpal veins, one opposite
each of the three medial interdigital clefts ; (2) thefradial dorsal
digital vein from the index finger. On the dorsum of each digit
look for two dorsal digital veins, one along the radial and one
along the ulnar border. The dorsal digital veins of the thumb
join the cephalic vein ; the ulnar dorsal digital vein of the little
finger usually joins the basilic vein ; the other dorsal digital
veins terminate in the dorsal metacarpal veins. The two dorsal
digital veins on each finger are united by many channels which
form a series of arcades, the dorsal digital venous arches. The



64 THE SUPERIOR EXTREMITY

superficial veins on the dorsum of the hand communicate through
the interdigital clefts with the deep and superficial veins of the
palm.

The superficial veins on the volar aspects of the fingers and in the palm
are small, and cannot as a rule be displayed in an ordinary dissection, but,
springing from a network in the superficial fascia of the palm, or appearing
in the superficial fascia of the volar aspect of the wrist, there is occasionally
a median antebrachial vein which passes proximally, along the middle
of the volar aspect of the forearm, towards the elbow. A short distance
distal to the elbow it either joins the median cubital vein or it divides
into two branches, the median basilic and the median cephalic, which
terminate respectively in the basilic and cephalic veins.

Accompanying the various superficial veins of the superior extremity
there are numerous lymph vessels which collect lymph from the regions
drained by the veins. Those which accompany the proximal part of the
cephalic vein, and which are derived partly from the dorsum of the
forearm and partly from the dorsum of the arm and the lateral part of
the shoulder, pass to the delto-pectoral and infraclavicular lymph glands ;
some of the lymph vessels which accompany the basilic vein end in the
superficial cubital glands, above the medial epicondyle ; the remainder, and
the efferents of the superficial cubital glands, accompany the proximal part
of the basilic vein, and, after piercing the deep fascia, they terminate either
in the brachial glands or the lateral group of axillary glands (Fig. 9).

The superficial lymph glands can often be found by a careful dissector,
but the superficial lymph vessels are difficult to demonstrate in an ordinary
dissecting-room " part." They appear as fine white strands, and are most
easily distinguished as they enter or leave the glands.

Vena Cephalica. The cephalic vein commences at the
radial end of the venous arch on the dorsum of the hand.
It receives the two dorsal digital veins from the thumb, and
then turns round the radial border of the distal part of the
forearm and ascends to the region of the elbow; there the
greater part of the blood which it carries is transmitted to the
basilic vein by the large median cubital vein. Proximal to
the level of the median cubital vein, the cephalic vein ascends
either along the lateral part of the biceps, or in the groove
at the lateral border of the biceps, to the lower border of the
pectoralis major; there it pierces the deep fascia (Fig. 31), and
then continues proximally in the groove between the pectoralis
major and the deltoid to the delto-pectoral triangle. In the
delto-pectoral triangle it crosses the lateral part of the pectoralis
minor, and turns medially between the clavicular part of the
pectoralis major and the costo-coracoid membrane. In this
terminal part of its course it lies anterior to the axillary artery,
but is separated from the artery by the costo-coracoid mem-
brane. Finally it pierces the costo-coracoid membrane and
joins the axillary vein. It receives (i) the dorsal digital veins



DISSECTION OF SUPERFICIAL STRUCTURES 65

of the thumb, (2) tributaries from the volar and dorsal aspects
of the forearm, (3) tributaries from the lateral and dorsal
aspects of the arm, (4) a tributary from the side of the shoulder,
and (5), immediately before it pierces the costo-coracoid
membrane, it is joined by the venae comites of the deltoid and
acromial branches of the thoraco-acromial artery. It is
accompanied by lymph vessels from the dorsum of the hand,
and the lateral and dorsal sides of the forearm and arm ;
those vessels terminate in the delto-pectoral lymph glands.

Vena Basilica. The basilic vein commences at the ulnar
end of the dorsal venous arch of the hand. It receives the
dorsal digital vein from the ulnar side of the little finger and
then ascends on the ulnar part of the dorsal surface of the
forearm. Below the elbow it turns round the ulnar border
of the forearm and ascends to the groove along the medial
border of the biceps brachii. About 30 mm. above the
medial epicondyle it is joined by the median cubital vein,
then it continues proximally to the level of the middle of the
arm, where it pierces the deep fascia. After it has pierced
the deep fascia, it runs along the medial side of the brachial
artery to the lower border of the teres major, where it becomes
the axillary vein ; only the termination of this part of the
vein can be seen at present, the remainder will be dis-
played in a later dissection. The tributaries of the basilic
vein are (i) the ulnar dorsal digital vein of the little finger,
(2) tributaries from the volar and dorsal aspects of the fore-
arm, (3) the median cubital vein, (4) tributaries from the
medial and posterior parts of the arm. It is accompanied
by lymph vessels from the dorsum and palm of the hand
and the volar and dorsal aspects of the forearm. Some
of the accompanying lymph vessels end in the superficial
cubital glands, which lie proximal to the medial epicondyle.
Others pass directly to the brachial and the lateral axillary
glands.

Vena Mediana Cubiti. The median cubital vein is a
large communicating vein which springs from the cephalic
vein about 25 mm. below the bend of the elbow, and
terminates in the basilic vein 30 mm. above the medial
epicondyle. As it crosses from the cephalic to the basilic
vein it receives tributaries from the volar aspect of the
forearm, it is separated from the distal part of the brachial
artery by a thickened portion of deep fascia called the

VOL. i 5



66



THE SUPERIOR EXTREMITY



lacertus fibrosus? and it is crossed either deeply or super-
ficially by the volar branch of the medial cutaneous nerve of
the forearm (Fig. 31).

The Lymph Vessels and Lymph Glands of the Superior Extremity.
With the exception of a few lymph vessels which the dissector may have



Jugular lymph trunk,



Subclavian lymph
Infraclavicular lymph glands



Delto- pectoral lymph glands,. 1^



Lymph vessels which accompany I
the cephalic vein"




"Internal jugular vein

Subclavian'vein
i Innominate vein

Broncho-mediastinal

lymph trunk



Axillary lymph glands

Lymph vessels which accompany

the basilic vein



"""Cubital lymph glands



FIG. 30. Diagram of the Superficial Lymph Vessels and Lymph Glands of
the Right Superior Extremity.

found passing to and from the axillary lymph glands (p. 29), the lymph
vessels of the superior extremity cannot be displayed in an ordinary
dissecting-room "part," and it is only occasionally in the hospital, the
post-mortem room, and in specially prepared subjects that an opportunity
for seeing the lymph vessels will occur. It is unfortunate that this should

1 The strengthening fibres of the lacertus fibrosus are derived from the
tendon of insertion of the biceps brachii.



DISSECTION OF SUPERFICIAL STRUCTURES 67

be the case, because the lymph vessels and lymph glands are of great
clinical importance, and their positions and connections must always be
kept in mind when infection by micro-organisms and the spread of malig-
nant growths is under consideration (Fig. 30).

For the main part the lymph vessels accompany the blood-vessels, but
they are much more numerous than the latter ; they are present in all tissues,
except cartilage ; and they contain a colourless fluid called lymph, which
drains into the smaller lymph vessels from the tissues amidst which they
lie. The lymph vessels unite together, like the veins, to form gradually
larger and larger vessels, which are however always relatively small as
contrasted with blood-vessels, and the lymph they carry finally enters two
terminal lymph vessels, the right lymph duct and the thoracic duct. Both
the terminal lymph vessels join big veins at the root of the neck behind
the sternal part of the clavicle, the right lymph duct ending in the
right innominate vein and the thoracic duct in the left innominate vein.
Therefore, eventually, all the lymph gathered from the tissues is poured
into the blood. In ordinary circumstances the lymph carries materials
which are distributed by the blood throughout the body, to the organs
which must utilise them or excrete them in order that the bodily health
may be maintained, but if micro-organisms have invaded the tissues or
malignant tumours have formed amidst them, the micro-organisms or
the poisons they form and cells of the malignant tumours may enter the
lymph vessels, and when that occurs it necessarily follows that they may
be distributed by the blood to all parts of the body. That naturally
occurs rapidly in the cases of any dissolved poisons, but the process may
be delayed in the cases of micro-organisms and the cells of malignant
tumours, for the lymph glands are interposed, like small filters, in the
courses of the lymph vessels, and micro-organisms and malignant cells are
frequently caught in them. The micro-organisms so caught may cause
inflammation of the glands and the malignant cells develop into new
malignant tumour formations. It is important therefore, in the considera-
tion of all cases of micro-organic infection and malignant tumour growth,
that the doctor should have a very clear idea of the possible lymph path-
ways by which the infection or the tumour may spread, and the positions
of the lymph glands which may, for a time, retard disaster and give
him the opportunity to deal successfully with the conditions which are
threatening.

It is probable that all lymph passes through at least one lymph gland
before it enters the terminal lymph vessels, and most lymph passes through
many glands. The lymph vessels which convey lymph to lymph glands
are called afferent lymph vessels, and those which convey it from glands
are efferent lymph vessels. Both the lymph vessels and the lymph glands
in the superior extremity, as in other parts of the body, form two main
groups, deep and superficial.

The deep glands are: (i) the deep cubital glands; (2) the brachial
glands ; (3) the axillary glands : (a) lateral, (b] anterior, and (c] posterior
(see p. 29) ; (4) the delto- pectoral glands ; (5) in some cases there are
a few scattered lymph glands associated with the deep arteries of the front
of the forearm.

The lymph from all the structures deep to the deep fascia is carried by
lymph vessels which accompany the blood-vessels to the nearest available
lymph glands. The deep cubital glands receive the lymph from the deep
parts of the hand and forearm, and part of the lymph from the elbow, and
pass it on to the brachial glands, which also receive lymph from the elbow
and the deep parts of the arm. From the brachial glands the lymph passes
to the lateral group of axillary glands.
I 5 a



68



THE SUPERIOR EXTREMITY



The siiperficial lymph glands are the superficial cubital glands which lie
in the fat of the front of the medial side of the arm immediately proximal
to the medial epicondyle (see p. 63).

The lymph from the skin and subcutaneous tissues of the superior
extremity forms two main streams, (i) From the palm, the ulnar border
and the ulnar part of the dorsal surface of the hand, the greater part of the
front, the ulnar border, and the ulnar part of the dorsal surface of the fore-
arm, it flows through a series of superficial lymph vessels which accompany
the tributaries and the distal part of the trunk of the basilic vein to the
superficial cubital glands. The efferent vessels from the superficial cubital
glands, reinforced by lymph vessels from the medial part of the arm,
accompany the proximal part of the basilic vein through the deep fascia ;
some of them end in the brachial glands, but the majority pass to the
lateral axillary glands. (2) The second stream flows from the radial part
of the dorsal aspect of the hand, the radial border, and the radial part of
the posterior surface of the forearm and the lateral part of the arm, through
a series of lymph vessels which accompany the cephalic vein. They end
in the delto- pectoral glands, which receive lymph also from the region
of the shoulder. The lymph from the lateral axillary glands and the
delto-pectoral glands passes to the infraclavicular glands, and thence on the
right side to the right lymph duct, and on the left side to the thoracic duct.

The lymph from the deep and superficial parts of the scapular region
flows mainly to the posterior axillary glands, and through them to the infra-
clavicular glands. The superficial and deep lymph vessels of the anterior
axillary region have already been traced. They carry lymph partly to the
anterior axillary and interpectoral glands, whence it passes to the infra-
clavicular glands, and partly directly to the infraclavicular glands, but they
also convey it to the sternal lymph glands, and they communicate with the
lymph vessels of the upper and anterior part of the abdomen (see p. 17
and Fig. 14).

When the superficial veins and their connections have
been cleaned and studied, the cutaneous nerves of the
superior extremity must be found and cleaned; they are:

1. The posterior supraclavicular nerves.

2. The intercosto-brachial nerve.

3. The medial cutaneous nerve of the arm.

4. The lateral brachial cutaneous nerve.

5. The posterior cutaneous nerve of the

arm.

cutaneous nerve of the



The medial
forearm.

The dorsal
forearm.

The lateral
forearm.



To the skin of the arm.



cutaneous nerve of the



To the skin of the arm and
the forearm.



cutaneous nerve of the \ To the forearm and ball of
the thumb.



the skin of the pato.



9. The palmar cutaneous branch of the'i

10. ThrpltLTcutaneous branch of the

ulnar nerve.
1 1 . The digital branches of the median nerve.

12. The digital branches of the ulnar nerve.

13. The superficial branch of the radial nerve and its dorsal digital

branches.

14. The dorsal branch of the ulnar nerve and its dorsal digital branches.



DISSECTION OF SUPERFICIAL STRUCTURES 69

Dissection. Turn to the proximal end of the limb and com-
mence with the intercosto - brachial nerve, which was severed
when the superior extremity was removed from the trunk. It
lies in the posterior part of the medial side of the arm, and is at
first deep to the deep fascia. Note the point at which it pierces
the deep fascia (Figs. 31, 32) and trace it to its termination near
the elbow. By means of its various branches it supplies the skin
on the medial side of the posterior part of the arm (Figs. 31, 32).

Find, next, the medial cutaneous nerve of the arm. It pierces
the deep of the fascia proximal third of the arm on the medial
side, and its branches supply the skin as far as the elbow in an
area anterior to that supplied by the intercosto-brachial nerve.

After the medial cutaneous nerve of the arm has been cleaned,
look for the branches of the medial cutaneous nerve of the fore-
arm, which supply the medial part of the skin of the arm. They
vary in number and size, but they usually pierce the deep fascia
along the line of the medial border of the biceps brachii and they
communicate with one another (Fig. 31).

The trunk of the medial cutaneous nerve of the forearm
either pierces the deep fascia close to the basilic vein, or it passes
through the same opening as the vein, and divides into its volar



Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 8 of 44)