D. J. (Daniel John) Cunningham.

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

. (page 14 of 44)
Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 14 of 44)
Font size
QR-code for this ebook


humeral ligaments. To see them the posterior part of the
capsule must be divided by a vertical incision and the head
of the humerus must be turned aside or removed. The
superior gleno-humeral ligament springs from the margin of
the glenoid cavity immediately anterior to the tendon of the
long head of the biceps brachii, and it passes to a small
pit situated on the proximal extremity of the humerus close
to the top of the intertubercular sulcus. The middle gleno-
humeral ligament is attached to the scapula immediately
above the notch on the anterior margin of the glenoid cavity,



SHOULDER-JOINT



and to the humerus in the region of the small tubercle.
Between it and the superior gleno-humeral ligament is the
opening from the joint into the subscapular bursa. The
inferior gleno-humeral ligament is a fan-shaped thickening.
It is attached by its smaller extremity to the scapula below
the notch in the anterior margin of the glenoid cavity, and,
by its broader end, to the neck of the humerus along a line



Conoid ligament

Trapezoid ligament

Coraco-acromial

ligament

Coracoid process



Middle gleno-
humeral ligament

Bursal opening
in capsule



Inferior gleno-
humeral ligament



Glenoid cavity




Long tendon
of biceps

Capsule of
shoulder-
joint



\ Labrum
glenoidale



FIG. 54. Shoulder-joint. The Articular Capsule has been cut across and
the Humerus removed.

passing from a lower part of the lesser to the greater tubercle.
It strengthens the lower and anterior part of the capsule
which is situated above the quadrilateral space.

Dissection. Complete the division of the capsular ligament,
divide the tendon of the biceps brachii and draw it through the
intertubercular aperture in the capsule, then separate the two
bones from one another.

Labrum Glenoidale (O.T. Glenoid Ligament). The labrum
glenoidale is the dense fibro- cartilaginous band which
surrounds the margin of the glenoid cavity of the scapula,



126 THE SUPERIOR EXTREMITY

and is attached to its rim. It deepens, and at the same
time serves to extend, the articular socket of the scapula.
The intimate connection which it presents with the capsule
of the joint can now be studied. Two tendons are also
closely associated with it, viz. the long head of the triceps
brachii below, and the long head of the biceps brachii above.

Long Head of the Biceps. The tendon of the long
head of the biceps is an important factor in the mechanism
of the shoulder- joint. It enters the capsule through the
opening between the two tubercles of the humerus, and
is prolonged over the head of the bone to the apex of the
glenoid cavity. Its attachment to the scapula should now be
examined. The tendon divides into three portions, viz. a
large intermediate part, which obtains direct attachment to
the scapula, and two smaller collateral parts, which diverge
from each other and blend with the labrum glenoidale. The
long head of the biceps brachii, by its position within the
capsule and in the deep sulcus between the tubercles of the
humerus, serves to keep the head of the bone in place, and
to steady it in the various movements at the shoulder-joint.

The synovial stratum lines the fibrous stratum of the
capsule of the joint, and is reflected from it upon the anatomical
neck of the humerus as far as the articular margin of the
head of the bone. The bursal protrusion of the bursa sub-
scapularis, under the tendon of the subscapularis muscle, has
already been noticed. The tendon of the biceps, as it
traverses the joint, is enveloped in a tubular sheath of the
membrane \ this sheath bulges out through the opening of the
capsule in the form of a bursa which lines the intertuber-
cular sulcus (Fig. 53).

Articular Surfaces. The smooth, glistening articular
cartilage which coats the head of the humerus is thickest
in the centre, and thins as it passes towards the edges. In
the case of the glenoid cavity the reverse of this will be
noticed.

Movements at the Shoulder-joint. The shoulder is a
ball-and-socket joint (enarthrosis), and consequently move-
ment in every direction is permitted, viz. (i) flexion, or
forward movement; (2) extension, or backward movement
(checked in its extent by the coraco-humeral ligament) ; (3)
abduction, or lateral movement (checked by the coraco-
acromial arch) ; (4) adduction, or medial movement (limited



PLATE VI



Greater tubercle Acromio-

ofhumerus Acromion clavicular joint Coracoid



Glenoid fossa




Spine of scapula



FlG 5 6fl. Radiograph of Shoulder Region with Arm fully abducted.



Conoid tubercle
of clavicle



Acromio-
Coracoid clavicular joint Acromion




Head of humeru?



Spine of scapula



Lower margin of
glenoid fossa



Lateral margin of
spine of scapula



FIG. $6b. Radiograph of Shoulder Region with Arm partly abducted.
Note ( i ) That the glenoid fossa is always directed slightly upwards.
(2) The relative positions of the head of the humerus and the
greater tubercle to the acromion. Compare with Fig. 55.



FOREARM AND HAND 127

by the coraco-humeral ligament). By combination of the
angular movements, in regular sequence, circumduction is
produced ; and rotation of the humerus, to the extent of
quarter of a circle, occurs also.

The muscles chiefly concerned in producing these move-
ments are : flexion the pectoralis major and the anterior
part of the deltoid ; extension latissimus dorsi, posterior part
of the deltoid, and the teres major; abduction the deltoid
and supraspinatus ; adduction pectoralis major, coraco-
brachialis, teres major, and latissimus dorsi ; rotation medially
subscapularis, pectoralis major, latissimus dorsi, teres
major ; rotation laterally infraspinatus, and teres minor ;
circumduction is produced by the action of different combina-
tions of these muscles.

The relations of the capsule are shown in Figs. 52, 53.



FOREARM AND HAND.

The skin has already been removed from the forearm and
hand, and the cutaneous veins and nerves have been exposed
and studied, but before proceeding with the deeper dissection
the dissector should re - examine the cutaneous veins and
nerves.

Vense Superficiales. The two large superficial veins, the
basilic and the cephalic, both spring from the venous arch
on the dorsum of the hand in which the superficial veins
from the fingers terminate (p. 63), and they are reinforced
by numerous tributaries from the dorsal and volar surfaces of
the limb. The basilic vein curves round the proximal part
of the ulnar border of the forearm on its way towards the
arm, whilst the cephalic vein turns round the distal part of
the radial border (Figs. 31, 32).

Nervi Cutanei. Two nerves supply the skin of the volar
aspect of the forearm : the volar branch of the medial cutaneous
nerve of the forearm on the medial side, and the lateral
cutaneous continuation of the musculo- cutaneous nerve on the
lateral side.

Three nerves supply the skin on the dorsal aspect of the
forearm : the dorsal branch of the medial cutaneous nerve of the
forearm on the medial side, branches of the lateral cutaneous
nerve on the lateral side, whilst the intermediate area is



128 THE SUPERIOR EXTREMITY

supplied by the distal branch of the dorsal cutaneous nerve of
the forearm, which is a branch of the radial nerve.

Four nerves supply the skin of the palm of the hand : in
the region of the hypothenar eminence the palmar cutaneous
branch of the ulnar nerve, in the region of the thenar emin-
ence the lateral cutaneous nerve of the forearm, and a twig from
the superficial division of the radial nerve, whilst the inter-
mediate part is supplied by the palmar cutaneous branch of the
median nerve.

Two nerves supply branches to the skin of the dorsum of
the hand: on the lateral part the superficial branch of the
radial nerve, and on the medial part the dorsal branch of the
ulnar nerve.

Two nerves supply the skin of the volar aspects of the
digits : the median and the ulnar. Three and a half digits fall
to the digital branches of the median nerve : the thumb, the
index, the middle, and the lateral half of the ring finger ; and
one and a half to the digital branches of the ulnar nerve, the
little finger and the medial half of the ring finger.

Three nerves supply the skin of the dorsal aspects of the
digits. Speaking generally, the proximal halves of the thumb,
the index, middle, and half the ring finger are supplied by
branches of the superficial division of the radial nerve. The
distal halves of the index, middle, and half the ring finger
are supplied by twigs of the digital branches of the median nerve,
and the remaining half of the ring finger and the little finger
receive twigs from the ulnar nerve.

After the cutaneous veins and nerves have been re-
examined the deep fascia of the forearm should be thoroughly
cleaned, if that has not already been done, and its special
points should be re-studied.

Fascia Antibrachii (Fascia of the Forearm). The deep
fascia which envelops the forearm is of considerable strength
and density. More particularly is that the case on the dorsal
aspect of the limb. In its proximal part it receives an
accession of fibres from the tendon of the biceps brachii, in
the form of the lacertus fibrosus. Some fibres are given to
it by the tendon of the triceps also. Near the elbow it
serves as a surface of origin for the numerous muscles which
spring from the epicondyles of the humerus, and from its
deep aspect dense septa pass between the fleshy bellies. The
septal partitions are indicated on the surface by a series of



FOREARM AND HAND 129

white lines. At the wrist it becomes continuous, anteriorly,
with the volar carpal ligament and the transverse carpal liga-
ment (O.T. ant. annular lig.\ whilst posteriorly it forms an
obliquely placed, thickened band, the dorsal carpal ligament
(post, annular lig.).

VOLAR SURFACE AND MEDIAL BORDER OF THE FOREARM.

In this dissection the following structures will be dis-
played :

1. The radial and ulnar arteries and their branches.

2. The median and ulnar nerves and their branches.

3. The deep branch and the superficial branch of the radial nerve.

4. The group of pronator and flexor muscles.

Dissection. The deep fascia must now be removed from the
forearm. Make two incisions through it, (i) a transverse
incision at the proximal border of the transverse carpal liga-
ment ; (2) a longitudinal incision from the apex of the cubital
fossa to the transverse incision. As the transverse incision is
made be careful not to injure the palmar cutaneous branches
of the median and ulnar nerves, the tendon of the palmaris
longus, the ulnar nerve and artery, and the mucous sheaths
of the flexors. The two palmar cutaneous nerves and the
tendon of the palmaris longus and the ulnar nerve and artery
pierce the deep fascia proximal to the transverse ligament and
pass across its superficial surface, but the ulnar nerve and artery
are bound down to the ligament by a more superficial band
called the volar carpal ligament, which passes from the pisiform
bone to the front of the transverse carpal ligament. The volar
carpal ligament is apt to be mistaken for the transverse liga-
ment, but the mistake should not be made, because the volar
carpal ligament lies superficial to the ulnar artery and nerve,
whilst the transverse ligament is deep to those structures.
Retain the volar carpal ligament in the meantime. The mucous
sheaths of the tendons lie immediately subjacent to the deep
fascia. Turn the two flaps marked out by the incisions to their
respective sides, dividing the septa which pass from their deep
surfaces between the adjacent muscles. Both flaps can be
followed to the dorsal border of the ulna, to the whole length of
which the deep fascia is attached, but for the present do not
reflect the lateral flap beyond the radial border of the forearm.
Near the elbow the muscles which spring from the medial and
lateral epicondyles gain additional origin from the deep surface
of the fascia. Where that is the case the fascia must be left
in situ, for attempts to remove it will only result in laceration of
the muscles.

Muscles of the Volar Aspect of the Forearm. The

muscles of the volar aspect of the forearm are arranged in a
superficial and a deep group. They comprise the flexors of
the wrist and digits, and also the pronators of the forearm.
VOL. i 9



130 THE SUPERIOR EXTREMITY

In the superficial group are the brachio-radialis, pronator teres,
the flexor carpi radialis, the palmaris longus, and the flexor
carpi ulnaris, in that order from the lateral to the medial
side. On a deeper plane lies the fleshy belly of the flexor
digitorum sublimis which only partially comes to the surface.
The deep group is composed of three muscles, placed in con-
tact with the bones and interosseous membrane of the fore-
arm, viz., the flexor digitorum profundus, in relation to the
ulna, the flexor pollicis longus, in relation to the radius, and
the pronator quadratus, closely applied to the distal ends of
both bones. The brachio-radialis lies along the lateral border
of the volar aspect.

The brachio-radialis extends from the lateral supra-con-
dylar ridge of the humerus to the distal end of the radius.
The pronator teres ends at the middle of the radius. The
flexor carpi radialis passes to the ball of the thumb, where
its tendon disappears into a cleft in the lateral border of
the transverse carpal ligament. The tendon of the pal-
maris longus lies medial to the tendon of the flexor carpi
radialis ; it passes anterior to the transverse carpal ligament
to join the intermediate part of the palmar aponeurosis.
Still more medial, descending to the pisiform bone, is the
tendon of the flexor carpi ulnaris. The tendons of the flexor
digitorum sublimis, enclosed in their mucous sheath, lie deep
to the palmaris longus between the flexor carpi radialis and
the flexor carpi ulnaris.

Dissection. Clean the brachio-radialis, from its origin from
the humerus to its insertion into the base of the styloid process
of the radius. To expose the insertion it will be necessary to
push backwards the tendons of the abductor pollicis longus and
the extensor pollicis brevis which overlap it posteriorly. Pull
the brachio-radialis aside and clean the radial artery and its
branches and the superficial branch of the radial nerve.

Arteria Radialis. The radial artery is the smaller of the
two terminal branches of the brachial artery, but its direction
gives it the appearance of being the continuation of the
parent trunk in the forearm. It takes origin in the cubital
fossa, opposite the neck of the radius, and it proceeds distally,
in the lateral part of the front of the limb, until it reaches
the distal end of the radius. There it turns round the
lateral border of the wrist and leaves the present dissection.
At first it lies between the pronator teres and the brachio-
radialis, and is overlapped to some extent on the lateral side



FOREARM AND HAND 131

by the fleshy belly of the latter muscle (Fig. 61). At a more
distal level it is placed between the brachio-radialis, on the
lateral side, and the flexor carpi radialis, upon the medial
side ; and that position it maintains as far as the wrist.
Where the muscles mentioned are fleshy the artery lies at
some depth from the surface; but when their tendons appear
it assumes a superficial position, and is covered merely by
the integument and fasciae. Throughout its whole length it
is closely accompanied by the vencs comites, and the super-
ficial division of the radial nerve lies along its lateral side
in the middle third of the forearm. More proximally, the
nerve is separated from the vessel by a slight interval ; whilst
distally, the nerve leaves the artery and turns round the lateral
margin of the forearm, under cover of the tendon of the
brachio-radialis.

Posteriorly, the radial artery is supported by the muscles
which clothe and find attachment to the front of the radius.
At its origin it rests upon the tendon of the biceps brachii ;
next it lies in front of the supinator, with some adipose
tissue intervening ; thence distally it is in contact with the
pronator teres, the thin radial head of the flexor digitorum
sublimis, the flexor pollicis longus, the pronator quadratus, and,
lastly, the distal end of the radius.

The radial artery is usually selected for the determination of the pulse.
When the tips of the fingers are placed upon the distal part of the forearm,
in the interval between the tendons of the brachio-radialis and flexor
carpi radialis, the pulsations of the vessel, in the living person, can readily
be felt.

Branches of the Radial Artery. In the forearm the
radial artery gives off the following branches, viz. :

1. The a. recurrens radialis.

2. The a. volaris superficialis.

3. The a. carpea volaris radialis.

4. Kami musculares.

The muscular branches are very numerous, and proceed from
the radial artery, at irregular points, throughout its whole
course in the forearm (Fig. 62).

The radial recurrent artery is a branch of some size. It
takes origin close to the commencement of the radial artery,
and, in the first instance, runs laterally between the brachio-
radialis and the supinator. There it comes into relation with



1 32 THE SUPERIOR EXTREMITY

branches of the radial nerve, and gives off several twigs for
the supply of the muscles arising from the lateral epicondyle
of the humerus. Somewhat reduced in size, it now turns
proximally, in the interval between the brachio-radialis and
brachialis, and ends, in front of the lateral epicondyle of the
humerus, by anastomosing with the anterior terminal branch
of the profunda brachii artery. It may be represented by
two or more vessels.

The superficial volar artery is a small, variable branch,
which arises a short distance proximal to the wrist, and runs
distally to end in the muscles of the ball of the thumb. Some-
times, however, it attains a larger size and a special importance,
because it is continued into the palm to complete the super-
ficial volar arch, on the lateral side.

The volar radial carpal artery is a minute twig which springs
from the radial at the distal border of the pronator quadratus
muscle. It runs medially, under cover of the flexor tendons,
and joins with the corresponding branch of the ulnar artery
to form the volar carpal arch.

The Ramus Superficialis and the Eamus Profundus of
the Nervus Radialis (O.T. Radial and Posterior Interos-
seous Nerves). It has already been noted that the radial
nerve ends proximal to the elbow, under cover of the brachio-
radialis muscle, by dividing into two terminal branches,
the superficial branch and the deep branch. Both branches
may now be studied in so far as they lie in the volar
part of the forearm. The ramus profundus soon dis-
appears from view by passing backwards, on the lateral
side of the radius, through the fibres of the supinator
muscle.

The superficial branch proceeds distally, under cover
of the fleshy belly of the brachio-radialis. In the middle
third of the forearm it lies along the lateral side of the radial
artery ; then it leaves the artery and winds round the lateral
margin of the limb, under cover of the tendon of the
brachio-radialis. It has been traced in the rest of its
course (p. 71). The superficial branch is a purely cutaneous
nerve ; and it gives off no branches until it gains the dorsal
aspect of the distal part of the forearm.

Dissection. Before the cleaning of the superficial flexor
muscles is commenced an attempt should be made to demonstrate
the mucous sheaths of the flexor tendons. They are the common



FOREARM AND HAND



133



sheath of the flexor digitorum sublimis and the flexor digitorum
profundus, the sheath of the flexor pollicis longus and the
sheath of the flexor carpi radialis.

If the sheaths are uninjured they can be distended with air
by means of a blowpipe, or by fluid forced in through a syringe.
If they have been injured they can still be explored with a blunt
probe.

Examine, first, the common sheath of the flexor tendons of
the fingers. Pick up a fold of the medial part of its anterior
wall within the forceps, and introduce the blowpipe or the
needle of the syringe into the base of the fold. Notice that as



Cephalic vein
Lateral cutaneous nerve

of the forearm v
Brachio-radialis



Radial artery



Medial cutaneous nerve
of the forearm
' Median nerve

Palmaris longus



Radial nerve,

superficial

branch

Extensor carpi
radialis longus




.Ulnar artery

Ulnar nerve
Medial cutane-
ous nerve of

' the forearm

^-Flexor carpi
ulnaris



"Basilic vein



Dorsal interosseous nerve

Extensor digitorum communis

Supinator muscle Anconaeus

Supinator muscle Tendon of biceps brachii

Dorsal cutaneous nerve of the forearm

FlG. 57. Transverse section through the Proximal Third of the
left Forearm.

the air or fluid enters it the sheath is distended, at first "proximally,
to about 25 mm. above the transverse carpal ligament, then the
distension passes distally, behind the transverse carpal ligament,
to the middle of the palm and along the little finger, as far as
the terminal phalanx, showing that the common flexor sheath
is continuous with the flexor sheath of the little finger. It may
also extend along the thumb, for, in a certain number of cases,
the sheath of the flexor pollicis longus communicates with the
common flexor sheath .

The sheath of the flexor carpi radialis is not easily distended
because it is enclosed for the greater part of its extent in an
osteo-fibrous canal. It extends from a short distance proximal
to the transverse carpal ligament to the base of the metacarpal
bone of the index finger. Open it at the proximal border of the
i 9 a



134 THE SUPERIOR EXTREMITY

ligament and investigate its course and direction with the aid of
a blunt probe.

If the sheath of the flexor pollicis longus has not already
been distended by the air or fluid thrown into the common
flexor sheath, pull the tendon of the flexor carpi radialis medially,
find the tendon of the flexor pollicis longus which lies behind
it, and either distend its sheath in the manner indicated or
examine it with a probe. It extends from one inch above the
transverse carpal ligament to the base of the terminal phalanx
of the thumb.

Now turn to the middle finger and make a small longitudinal
incision through the flexor sheath opposite the middle of the
second phalanx. A blunt probe introduced through the incision
can be passed distally to the base of the terminal phalanx and
proximally to the level of the head of the metacarpal bone. The
conditions are the same in the cases of the index and ring fingers,
therefore the digital sheaths of the index, middle, and ring fingers
dp not communicate with the common flexor sheath. If the
digital sheath of the little finger is opened in a similar manner
no difficulty will be experienced in passing a probe along it into the
common flexor sheath, and if the digital sheath of the thumb is
opened and a little care exercised a probe can be passed along it,
and behind the transverse carpal ligament, to the proximal limit
of the mucous sheath of the flexor pollicis longus tendon.

Mucous Sheaths of the Flexor Tendons. As the tendons
of the flexor digitorum sublimis, the flexor digitorum
profundus, and the flexor pollicis longus pass behind the
transverse carpal ligament they are accompanied by the
median nerve and they are enveloped in two mucous
sheaths (Fig. 58). One sheath surrounds the flexor pollicis
longus,- the other surrounds the tendons of both the flexor
sublimis and the flexor profundus, and it may enclose
also the median nerved The sheaths, therefore, line a
"carpal tunnel" which is bounded superficially by the
transverse carpal ligament and dorsally by the carpal bones,
and they greatly facilitate the free play of the tendons between
the transverse carpal ligament and the carpus. As already
stated, the sheaths are two in number. Both sheaths are pro-
longed proximally, into the forearm, for 25 mm. (one inch) or
more, and both are carried distally into the palm in the form
of diverticula upon the diverging tendons. The diverticula in
relation to the tendons which go to the index, middle, and ring
fingers end near the middle of the palm. Those upon the
tendons of the thumb and little finger, however, are prolonged
distally into the digits, and line the fibrous sheaths which
confine the tendons upon the volar aspects of the phalanges
(Fig- 57)-



FOREARM AND HAND 135

The mucous sheath which invests the tendons of the flexor



Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 14 of 44)