D. J. (Daniel John) Cunningham.

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on the volar surface of the interosseous membrane, deep to
the pronator quadratus, to the carpus, where it terminates in
the volar carpal arch.

The ulnar carpal arteries are two small arteries, which
partially encircle the wrist. The volar ulnar carpal artery
runs laterally, under cover of the tendons of the flexor digi-
torum profundus, and anastomoses with the volar carpal
branch of the radial artery. From the arch, thus formed,
small twigs are given to the volar aspect of the carpal bones
and joints. The dorsal ulnar carpal artery gains the dorsal
aspect of the carpus by winding round the medial margin of
the limb immediately proximal to the pisiform bone, and
under cover of the tendon of the flexor carpi ulnaris.

Nervus Ulnaris. The ulnar nerve, which was traced in
the dissection of the arm as far as the interval between the
olecranon and medial epicondyle of the humerus, enters the
forearm between the two heads of the flexor carpi ulnaris. It
proceeds distaliy, on the volar surface of the flexor digitorum
profundus and under cover of the flexor carpi ulnaris, in the
volar part of the medial side of the forearm. Close to



FOREARM AND HAND 145

the wrist it becomes superficial, upon the lateral side of the



Pronator teres

Flexor carpi radialis

Palmaris longus




Flexor digitorum sublimis

Palmaris longus

Flexor carpi radialis
Radial nerve, superf. br.
Radial head of flexor
digitorum sublimis
Median nerve

Median artery
Radial artery

Radial head of flexor
digitorum sublimis

Flexor pollicis longus



Radial arte



Abductor pollicis
longu



FIG. 63. Dissection of the volar aspect of the Forearm ; the superficial
muscles are cut short and turned aside, and the deeper parts are still
further displayed by the separation of the flexor digitorum sublimis from
the flexor carpi ulnaris along the line of the intermuscular septum which
intervenes between them.

tendon of the flexor carpi ulnaris, and it reaches the palm by
VOL i. 10



Triceps brachii
Ulnar nerve
Olecranon

Fibrous arch between heads
of flexor carpi ulnaris



Ulnar nerve

Branch to flexor digitorum
irofundus

ranch to flexor carpi
ilnaris



Flexor digitorum
profundus
Ulnar nerve



^ Ulnar nerve
ind artery



Dorsal branch of ulnar nerve
Flexor digitorum profundus

Pronator quadratus



146 THE SUPERIOR EXTREMITY

passing superficial to the transverse carpal ligament. In the
proximal third of the forearm the ulnar nerve is separated from
the ulnar artery by a considerable interval, but in the distal
two-thirds it is closely applied to the medial side of the
vessel.

In the forearm the ulnar nerve gives off:

1. Kami articulares.

2. Kami Musculares, | to t h 1 fl " or Carpi ulnaris an , d t ! ie medial P art

^ 01 tne nexor digitorum profundus.



3. Kami cutanei, { ramus J-utaneus palmaris.

^ramus dorsahs manus.

The articular branches spring from the ulnar nerve as it
lies in the interval between the olecranon and the medial
epicondyle of the humerus, and pass to the elbow-joint.

The muscular branches are given off immediately distal to
the articular branches. They supply the flexor carpi ulnaris
and the medial part of the flexor digitorum profundus.

The palmar cutaneous branch is a minute twig which has
already been seen piercing the fascia of the forearm, im-
mediately proximal to the transverse carpal ligament. It arises
about the middle of the forearm and proceeds distally upon
the ulnar artery, to be distributed in the palm of the hand.

The dorsal branch is a nerve of some size which springs
from the ulnar trunk about 6-7-5 cm - ( two an d a half or
three inches) proximal to the wrist. It winds round the
medial margin of the forearm, under cover of the flexor carpi
ulnaris, and reaches the dorsum of the hand immediately
distal to the prominence formed by the distal end of the ulna.
From that point onwards it has been traced in the superficial
dissection (p. 71).

Nervus Medianus. As its name implies, the median nerve
passes down the middle of the forearm.

In the proximal part of the forearm the median nerve lies in
the cubital fossa upon the medial side of the ulnar artery.
It leaves the fossa by passing between the two heads of the
pronator teres, and as it does so it crosses the ulnar artery,
but is separated from it by the ulnar head of the muscle.
From that point the median nerve runs distally between the
flexor digitorum sublimis superficially and the flexor digitorum
profundus deeply. Near the wrist it becomes superficial, and
lies in the interval between the tendons of the palmaris longus,
on the medial side, and the flexor carpi radialis, on the lateral



FOREARM AND HAND



Flex. dig. sublim
Pronator teres
Brachialis ~~^
Flex. poll. long.
Biceps brachii



side. Finally it leaves the
forearm by passing deep
to the transverse carpal
ligament. A small artery,
the a. mediana, a branch of
thevolar interosseous artery,
accompanies the median
nerve. Sometimes this vessel
attains a considerable size.

As the median nerve
enters the forearm it gives
off numerous branches for
the supply of muscles, and
near the wrist it supplies
a palmar branch, which has
already been dissected (p.
70).

The muscular branches
supply all the muscles which
spring from the medial
epicondyle of the humerus,
with the single exception of
the flexor carpi ulnaris; viz.,
the pronator teres, the flexor
carpi radialis, the palmaris
longus, and the flexor digi-
torum sublimis.

It supplies also a long
slender twig volar inter-
osseous nerve which goes
to the deep muscles on the
volar aspect of the fore-
arm.

Deep Structures on the
front of the Forearm.
The connections of the
deep muscles must now be
studied.

The flexor digitorum pro-
fundus is the large muscle
which clothes the volar and
medial surfaces of the ulna; the flexor pollicis iongus is placed
i 10 a




FIG. 64. Volar aspect of Bones of
Forearm with Muscular Attachments
mapped out.



148 THE SUPERIOR EXTREMITY

upon the volar surface of the radius; while the pronator
quadratus is a quadrate fleshy layer closely applied to both
bones immediately proximal to the wrist. The volar inter-
osseous artery and nerve proceed distally in the interval
between the flexor profundus and flexor pollicis longus.

M. Flexor Digitorum Profundus. The deep flexor of
the fingers springs from the volar and medial surfaces of
the ulna in its proximal three -fourths. It derives fibres
also from the volar surface of the interosseous membrane
and the aponeurosis by which the flexor carpi ulnaris takes
origin from the dorsal border of the ulna. The fleshy mass
gives place to four tendons for the medial four digits, but
only one of them that for the index finger becomes
separate and distinct in the forearm. The tendons proceed
distally, deep to the transverse carpal ligament, into the palm.
The flexor digitorum profundus is supplied by the volar
interosseous branch of the median and by the ulnar nerve. It
is a flexor of all the joints of the fingers, and of the wrist.

M. Flexor Pollicis Longus. The flexor pollicis longus
arises from the proximal two-thirds of the volar surface of
the radius. It takes origin also from the adjacent part of
the volar surface of the interosseous membrane. A rounded
tendon issues from the fleshy belly, and proceeds into the
palm, deep to the transverse carpal ligament.

In many cases the flexor pollicis longus has an additional
slender head of origin, which springs from the medial border
of the coronoid process of the ulna, or the medial epicondyle
of the humerus. The flexor pollicis longus is supplied by
the volar interosseous nerve. It is a flexor of all the joints
of the thumb and of the wrist.

M. Pronator Quadratus. The quadrate pronator muscle
takes origin from the distal fourth of the volar surface of
the ulna, and is inserted into the distal third of the volar
surface of the radius. It is supplied by the volar interosseous
nerve. It is pronator of the forearm and hand.

Dissection. Divide the pronator quadratus vertically and
clean the part of the volar interosseous artery which lies
behind it.



WRIST AND PALM.
In this dissection the following structures will be found :



FOREARM AND HAND 149

1. Palmaris brevis muscle and the palmar cutaneous nerves.

2. Palmar aponeurosis.

3. Superficial volar arch and its branches.

4. Median and ulnar nerves and their branches.

5. Volar carpal ligament, transverse carpal ligament, the flexor tendons,

and their mucous sheaths.

6. The lumbrical muscles.

7. Short muscles of the thumb and little finger.

8. Deep volar arch and its branches.

9. Princeps pollicis artery and radial volar artery of the index finger.

Before proceeding with the dissection of the palm the
student should revise the surface anatomy of the region,
making use of his own hands as well as of his " part " for
the purpose ; and he should re-study the superficial vessels
and nerves, and the deep fascia which have already been
displayed (p. 73). After the revision is completed, the
attachments and relations of the palmaris brevis muscle
must be noted.

Surface Anatomy. In the centre of the palm the depres-
sion, known as the "hollow of the hand," may be noted.
Along the medial border of the palm the hollow is bounded by
a rounded elevation, called the hypothenar eminence, which is
produced by the subjacent short, intrinsic, muscles of the little
finger. The thenar eminence, or ball of the thumb, formed by
the short muscles of that digit, is the marked prominence which
limits the palmar hollow proximally and on the lateral side ;
whilst the transverse elevation at the roots of the fingers,
which corresponds to the metacarpo-phalangeal articulations,
constitutes the distal boundary of the central palmar depres-
sion. Two pronounced bony projections on the anterior aspect
of the wrisr cannot fail to attract attention when the hand is
bent dorsally. The more prominent of the two is situated at
the proximal extremity of the thenar eminence, and is formed
by the tubercle of the navicular bone and the vertical ridge on
the volar surface of the os multangulum majus ; the other is
placed at the proximal end of the hypothenar eminence, and
is somewhat obscured by the soft parts attached to it. It is
caused by the pisiform bone, and when taken firmly between
the finger and thumb a slight degree of gliding movement can
be communicated to it. Traversing the thick integument of
the palm, three strongly marked furrows are apparent. One
begins at the elevation formed by the navicular and os mult-
angulum majus and curves distally and laterally, round the
base of the thenar eminence, to the lateral margin of the
1106



THE SUPERIOR EXTREMITY



hand. A second crosses the palm transversely. Commencing
at the middle of the lateral border of the hand, where the
first furrow ends, it runs medially, but, as a general rule,



A. volaris indicis radialis



Transverse

carpal

ligament



Ulnar nerve
Ulnar artery




Princeps pollicis



Branch to muscles
of thumb

Superficial volar artery



Median nerve
Radial artery

FIG. 65. Diagram of Nerves and Vessels of Hand in relation to Bones
and Skin Markings.

it fades away upon the hypothenar eminence. The third
furrow begins near the cleft between the index and middle
fingers, and proceeds medially, with a gentle curve across
the hypothenar eminence, to the medial margin of the hand.
The transverse cutaneous furrows at the roots of the fingers,



FOREARM AND HAND 151

and on the palmar aspects of the interphalangeal joints, should
also be noticed. The furrows at the roots of the fingers are



Palmaris longus
Flexor carpi ulnaris



Ulnar artery

Transverse carpal ligament
Pisiform bone

Palmaris longus
Palmaris brevis

Abductor digiti quin



Flexor digiti quinti
brevis

Palmar aponturosis
(intermediate part)

4th lumbrical, with

digital artery and

nerves

3rd lumbrical, with

digital artery and

nerves



Superficial transverse
ligament




Flexor sublimis

Brachio-radialis
Flexor carpi radialis
Radial artery

Median nerve

Abductor pollicis longus

Superficial volar artery

Opponens pollicis

Abductor pollicis brevis

Flexor pollicisbrevis



ist lumbrical, with
digital nerve and
arteria indicis radialis



2n.d lumbrical, with digital
artery and nerve



FIG. 66. Superficial Dissection of the Palm. The intermediate part of the
palmar aponeurosis has been left in position, whilst the lateral and medial
portions have been removed to display the short muscles of the thumb
and little finger.



placed over the palmar aspects of the proximal phalanges,
about 25 mm. (one inch) distal to the metacarpo-phalangeal
joints. The proximal of the two furrows on the front of a

i 10 c



152 THE SUPERIOR EXTREMITY

proximal interphalangeal joint is placed immediately over
the articulation, whilst in the case of the distal inter-
phalangeal joints the single crease which is usually present
is situated immediately proximal to the articulation. On
the back of the hand the metacarpal bones can be readily
felt, whilst their distal extremities, or heads, form the promin-
ences known as the "knuckles."

M. Palmaris Brevis. This small cutaneous muscle con-
sists of a series of fasciculi which are frequently separated
from one another by distinct intervals. As a whole it
forms a thin fleshy layer which covers the deep fascia on the
proximal one and a half inches of the hypothenar eminence.
It springs from the distal margin of the transverse carpal
ligament and the medial border of the strong intermediate
part of the palmar aponeurosis, and it is inserted into the
skin of the medial border of the hand. It lies superficial
to the ulnar artery, the superficial part of the ulnar nerve, and
to the deep fascia covering the muscles of the hypothenar
eminence. It is supplied by the superficial division of
the ulnar nerve.

Dissection. Reflect the palmaris brevis to its origin from
the intermediate part of the palmar aponeurosis, and secure
the branch from the superficial division of the ulnar nerve which
supplies it. Remove the medial part of the palmar aponeurosis
from the muscles of the hypothenar eminence. Clean the ulnar
artery to the point where it disappears under cover of the inter-
mediate part of the palmar aponeurosis. Note that, as it passes
by the medial side of the hook of the os hamatum, it sends a
deep branch into the substance of the palm. Clean the ulnar
nerve as it lies on the medial side of the hook of the hamatum
and secure its two terminal branches : (i) A superficial branch,
which divides into the digital branch for the medial side of the
little finger, and a branch which divides to supply the adjacent
sides of the little and ring fingers ; and (2) a deep branch which
accompanies the deep branch of the ulnar artery into the depths
of the palm. Find the branches which the deep division of the
ulnar nerve gives to the short muscles of the little finger ; then
insert the handle of the scalpel into the cleft into which the deep
divisions of the artery and nerve pass, and carry it distally to
separate the abductor digiti quinti muscle, on the medial side,
from the flexor digiti quinti brevis and the opponens digiti quinti
on the lateral side. The opponens lies on a deeper plane than
the short flexor.

Short Muscles of the Little Finger. There are three
short muscles of the little finger : the abductor, the short
flexor, and the opponens. They are all supplied by the deep
branch of the ulnar nerve.



FOREARM AND HAND



153



M. Abductor Digit! Quinti. The abductor is the largest
of the three short muscles of the little finger. It arises from
the pisiform bone, and is inserted into the medial side of
the base of the first phalanx of the little finger.

M. Flexor Digiti Quinti Brevis. The short flexor of
the little finger is a muscle of very variable size. It springs
from the hook of the os hamatum and the adjacent part
of the distal border of the transverse carpal ligament, and is
inserted, with the abductor digiti quinti, into the medial side



Os capitatum Os lunatum
Os multangulum minus
Os naviculare manus
Abductor pollicis brevis
Os multangulum maju

Opponens pollicis
Abductor pollicis longus



Flexor carpi radialis




s hamatum
Os triquetrum
Flexor carpi ulnaris
Os pisiforme
Abductor digiti quinti
Flexor digiti
quinti brevis

exor carpi ulnaris



Opponens digiti quinti



Palmar interossei



M.I.

Adductor pollicis



FIG. 67. Volar aspect of the Bones of the Carpus and Metacarpus
with Muscular Attachments mapped out.

of the base of the first ohalanx of the little finger. It is
not uncommonly incorporated, to a greater or less extent,
with the opponens digiti quinti.

M. Opponens Digiti Quinti. The opponens of the little
finger lies on a deeper plane than the short flexor. It arises
from the hook of the os hamatum and the distal border of
the transverse carpal ligament, and is inserted into the whole
length of the medial part of the volar aspect of the meta-
carpal bone of the little finger.

Dissection. After the short muscles of the little finger have
been studied, clean away the slip of the palmar aponeurosis



154 THE SUPERIOR EXTREMITY

which goes to the thumb, taking care to avoid injury to the
digital nerves of the thumb. Next separate the apex of the
intermediate part of the palmar aponeurosis from the tendon of
the palmaris longus and from the transverse carpal ligament,
and reflect the intermediate part of the aponeurosis distally to
the roots of the ringers. Do not fail to note that, from its medial
and lateral margins, septa pass dorsally into the palm separat-
ing the muscles of the thenar and hypothenar eminences from
the tendons of the long flexors of the fingers. The septa must
be divided as the aponeurosis is reflected. Continue the reflection
until the deep surfaces of the processes which pass to the fingers
are fully exposed. Note that, at the roots of the fingers, each
process divides into two slips. As the two slips pass dorsally
they form an arch over the two flexor tendons which pass into
the tendon sheath of the finger, and they become attached to
the sheath of the tendons, to the transverse ligament which binds
the heads of the metacarpal bones together, and to the deep
fascia of the dorsum of the finger. Define the distal border of
the transverse carpal ligament, but leave in position the part
of the volar carpal ligament which binds the ulnar artery and
nerve to the volar aspect of the transverse carpal ligament.

The structures exposed by the reflection of the inter-
mediate part of the palmar aponeurosis are the contents of
the intermediate compartment of the palm. They are :

1. The continuation of the ulnar artery as the superficial

volar arch.

2. The digital branches from the arch to the clefts between

the fingers and to the medial side of the little finger.

3. The terminal branches of the median nerve.

4. The branch of the superficial division of the ulnar nerve

to the adjacent sides of the ring and little fingers.

5. The flexor tendons, surrounded by their mucous sheath.

6. The proximal parts of the mucous sheaths of the index,

middle, and ring fingers.

7. The four lumbrical muscles.

Fascial Compartments of the Palm. The two septa which
pass from the margins of the intermediate part of the palmar
aponeurosis into the depths of the palm have been noted
as they were divided. They join a layer of fascia which
lies on the volar surfaces of the interosseous muscles and
the adductor of the thumb and the deep volar arterial
arch. There are, therefore, in the palm, three fascial
compartments, which lie deep to the palmar aponeurosis.
(i) An intermediate compartment which contains the flexor
tendons, the lumbrical muscles, the superficial volar arch
and its branches, and the terminal branches of the median



PLATE IX



ist volar
metacarpal
artery
Superficial
volar arch







FIG. 68. Radiograph of a Hand in which the Arteries were injected.

Note ( i ) That the injection is incomplete.

(2) That the superficial volar arch is formed by the anastomosis

of the superficial branch of the ulnar artery with the
princeps pollicis artery.

(3) That the volar radial artery of the index finger is a branch

of the superficial volar arch.

(4) The relation of the deep volar arch to the metacarpal bones.



FOREARM AND HAND 155

nerve; (2) a medial compartment enclosing the short
muscles of the little finger, and the superficial division of
the ulnar nerve ; (3) a lateral compartment enclosing the
muscles of the thumb. Fluid or pus which collects in
the intermediate compartment can spread into the forearm
behind the transverse carpal ligament, and distally to the
clefts between the fingers, but it is excluded from the lateral
and medial compartments by the septa which pass into
the palm from the margins of the intermediate part of the
palmar aponeurosis.

Dissection. Clean the superficial volar arch from the ulnar
to the radial side, where it is completed by the anastomosis of
the ulnar artery either with the superficial volar branch of the
radial artery,- with the radialis indicis, or with a branch of the
princeps pollicis artery. Clean also the four digital branches
which the arch gives to the fingers. Then clean the palmar
part of the median nerve and its branches. The median nerve
enters the palm at the distal border of the transverse carpal
ligament. There it is flattened from before backwards and
expanded from side to side. It divides, almost immediately, into
two branches, a smaller lateral and a larger medial. Follow
the lateral branch first. Soon after its origin it gives off, from its
lateral side, a stout branch to supply the short muscles of the
thumb. Secure that branch at once, and follow it across the
superficial surface of the flexor pollicis brevis to the point where
it disappears under cover of the abductor pollicis brevis. More
distally the lateral branch of the median nerve divides into three
digital branches, two for the thumb and one for the radial side
of the index finger. No especial care is needed as the branches
to the thumb are cleaned, but the branch to the index finger
gives a fine twig to the first lumbrical which will be destroyed
unless care is exercised. The larger medial division of the
median nerve divides into two branches, one for the adjacent
sides of the index and middle fingers, and one for the adjacent
sides of the middle and ring fingers. Care must be exercised as
each is cleaned, for the first gives a fine twig to the second
lumbrical muscle which should not be missed, and the second is
connected with the lateral branch of the superficial division of
the ulnar nerve by a communicating twig which should be secured
now if it was not found when the ulnar nerve was cleaned.

Arcus Volaris Superficial (O.T. Superficial Palmar
Arch). The term superficial volar arch is applied to an arterial
arcade which lies immediately subjacent to the intermediate
part of the palmar aponeurosis, its most distal point being
situated at the level of the distal border of the fully abducted
thumb. It is formed by the ulnar artery. That artery
crosses the volar surface of the transverse carpal ligament,
immediately lateral to the pisiform bone, then it passes across



156 THE SUPERIOR EXTREMITY

the medial side of the apex of the hook of the os hamatum.
A short distance distal to the hook of the os hamatum it
turns laterally, pierces the septum which separates the medial
from the intermediate fascial compartment of the palm, and
crosses the intermediate compartment, lying between the
intermediate part of the palmar aponeurosis, which is super-
ficial to it, and the terminal branches of the median nerve
and the flexor tendons, which are deep to it. At the lateral
border of the intermediate fascial compartment it unites with
a branch of the radial artery, either the superficial volar, or
the radialis indicis, or the princeps pollicis. The arch
lies, therefore, in the medial and intermediate fascial com-
partments of the palm. In the medial compartment it lies
upon the flexor brevis and opponens digiti quinti muscles and
is covered by the palmaris brevis. In the intermediate
compartment it lies upon the flexor tendons and the digital
branches of the median nerve, and it is covered by the
intermediate part of the palmar aponeurosis.

As the ulnar artery lies on the transverse carpal ligament,
before it becomes the superficial volar arch, it gives off a pro-
funda branch which passes deeply into the palm, with the



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