D. J. (Daniel John) Cunningham.

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

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deep division of the ulnar nerve, between the abductor
digiti quinti muscle medially and the flexor digiti quinti
brevis laterally. That branch will be traced in the deep
dissection of the palm. From the superficial arch itself
small twigs are given off to the adjacent tendons and fascia,
but the chief branches are the four digital arteries which
spring from the convexity of the arch. The first of the four
remains undivided. It runs to the medial border of .the
little finger, along which it passes to the terminal phalanx.
The other three branches, 2nd, 3rd, 4th, pass towards the
interdigital clefts, where each divides, at the level of the
bases of the first phalanges, into two branches, which supply
the sides of the adjacent fingers, the second supplying the
little and ring fingers, the third the ring and middle, and the
fourth the middle and index fingers (Figs. 68, 69).

There are certain practical points to be noted in associa-
tion with the digital arteries. The first crosses the lateral
branch of the superficial division of the ulnar nerve and the
short muscles of the little finger The undivided parts of
the second, third, and fourth lie in line with the inter-
digital clefts between the fingers ; each is situated between



FOREARM AND HAND



a pair of flexor tendons and is superficial to a digital
nerve and a lumbrical muscle. As the branches run along
the sides of the fingers their relationship to the nerves is



Flexor carpi ulnaris
Ulnar artery

Dorsal branch of ulnar nerve

Ulnar nerve

Deep branch of ulnar nerve

Abductor digiti quinti

Deep branch of ulnar artery

Superficial part of ulnar nerve
Opponens digiti quinti



Abductor digiti
quinti

Flexor digiti
quinti brevis

4th lumbrical



3rd lumbrical




Flexor digitorum sublimis
Flexor carpi radialis
Median nerve
Radial artery
Superficial volar artery
Transverse carpal ligament
Abductor pollicis longus

Abductor pollicis brevis
.Opponens pollicis

Median nerve
Flexor pollicis brevis



Abductor pollicis
brevis

Superficial volar arch

Adductor pollicis,
transverse part.



ist lumbrical



and lumbrical



FIG. 69. The parts in the Palm which are displayed by the removal of the
Palmar Aponeurosis. In the specimen from which the drawing was taken
the arteria volaris indicis radialis and the arteria princeps pollicis took
origin from the superficial volar arch.



changed ; the nerves become superficial or volar and the
arteries lie behind the nerves. Opposite the terminal
phalanx the two arteries of each finger join to form an arch
from which a great number of fine branches are distributed



158 THE SUPERIOR EXTREMITY

to the pulp of the finger and to the bed upon which the
nail rests.

At the cleft of the finger immediately before it divides,
each digital artery is joined by the corresponding volar
metacarpal artery from the deep volar arch; and, as the
branches run along the sides of the fingers, they give off
numerous twigs to supply the skin, the flexor tendons and
the joints of the fingers.

The superficial volar arch is not uncommonly absent in whole or in
part. In such cases the digital arteries are replaced by the volar meta-
carpal branches of the deep volar arch.

Nervus Medianus. The median nerve was traced to the
proximal border of the transverse carpal ligament when the
front of the forearm was dissected. As it passes from the
forearm to the palm of the hand it lies behind the transverse
carpal ligament at the lateral margin of the tendons of the
flexor digitorum sublimis (Fig. 60) and in close relation
with the mucous sheath which surrounds those tendons.
Near the distal border of the transverse carpal ligament it is
first flattened antero-posteriorly and then it divides into a
smaller lateral, and a larger medial division. The lateral
division gives off a branch which supplies the short abductor, the
opponens and the short flexor of the thumb ; then it divides
into three digital branches, of which two go to the sides of
the thumb and the third to the radial side of the index
finger. The digital branches supply the skin, tendons,
ligaments and joints of the regions to which they are dis-
tributed. In addition the branches to the medial side of
the thumb and the radial side of the index digit give branches
to the fold of integument which stretches between the roots
of those digits, and the nerve to the index finger also gives
a branch to the first lumbrical muscle.

The larger medial division divides into two branches. One
runs towards the cleft between the index and middle fingers
and divides to supply the adjacent sides of those fingers ; before
it divides it gives a muscular branch to the second lumbrical
muscle. The second branch of the medial division divides,
in a similar manner, to supply the adjacent sides of the
middle and ring digits, but before it divides i gives a
communicating twig to the lateral branch of the superficial
division of the ulnar nerve. It sometimes gives a muscular



FOREARM AND HAND 159

branch to the third lumbrical muscle. In the palm the
digital branches of the median nerve pass distally deep to
the superficial volar arch and its digital branches, but as they
approach the fingers they become superficial to the digital
arteries. Further, it should be noted that those branches
of the median nerve which supply the adjacent sides of
fingers divide at a more proximal level than that at which
the digital arteries divide.

As they run along the sides of the fingers the digital
nerves send branches to the skin of the whole of the volar
aspect, and to the skin of the dorsal aspects of the second
and third phalanges. At the extremity of the finger each
nerve of supply divides into two branches. One of the two
ramifies in the pulp of the finger and the other passes dorsally
to the bed of the nail.

If the dissector exercises sufficient care in the dissection
of the branches of the digital nerves he will find minute oval,
seed-like bodies attached to the smaller twigs. They are
special sensory end organs called Pacinian Bodies.

It follows, from what has already been pointed out, that,
in the region of the hand, the median nerve supplies five
muscles and the skin of three and a half digits. The
muscles are the abductor pollicis brevis, the opponens
pollicis, the superficial head of the flexor pollicis brevis and
the two most lateral lumbrical muscles ; the digits are
the pollex, the index, the medius and the radial half of the
annularis.

Nervus Ulnaris. The palmar continuation of the ulnar
nerve enters the palm by passing superficial to the transverse
carpal ligament. As it lies secure from the effects of pressure,
under the shelter of the pisiform bone and upon the medial
side of the ulnar artery, it divides into two terminal branches
a superficial and a deep.

The deep branch passes to the medial side of the hook of
the os hamatum and then dips, deeply, into the palm, with
the deep branch of the ulnar artery, through the cleft
between the abductor digiti quinti and the flexor digiti quinti
brevis. It supplies the short muscles of the little finger as
it passes between them, and afterwards gives branches to
numerous other muscles. Its further course and distribution
will be seen when the deep part of the palm is dissected
(p. 170).



160 THE SUPERIOR EXTREMITY

The superficial branch passes distally, under cover of the
palmaris brevis, to which it gives a twig of supply. Whilst
under cover of the palmaris brevis it divides into two digital
branches. The medial of the two branches passes to the
medial side of the little finger. The lateral branch pierces
the septum which passes dorsally from the medial border of
the intermediate part of the palmar aponeurosis, and enters
the intermediate compartment of the palm. There it is joined
by a communicating branch from the first medial digital
branch of the median nerve, and then it divides into two
branches which supply the adjacent sides of the ring and
little fingers.

Dissection. After the branches of the median and ulnar
nerves have been examined, remove the lateral part of the palmar
aponeurosis from the muscles of the thenar eminence, but
preserve their nerve of supply, which has already been found.
As soon as the aponeurosis is removed two muscles are exposed ;
they are the abductor pollicis brevis and the superficial head of
the flexor pollicis brevis. The abductor is the lateral muscle ;
pass the handle of the scapel behind its lateral border and lift
the muscle from the subjacent opponens pollicis, then divide
the abductor about the middle of its length ; turn the proximal
part towards its origin, and the distal part towards its insertion.
When that has been done the opponens will be exposed, and
must be cleaned. Next divide the short flexor at its middle and
reflect it towards its extremities. The reflection of the short
flexor will bring into view parts of the adductor of the thumb,
emerging from behind the flexor tendons of the fingers, and
along the medial border of the opponens pollicis the tendon of
the flexor pollicis longus will be seen ; it is enclosed in its mucous
sheath, which should not be injured.

At this stage the mucous sheaths of the flexor tendons may
be re-examined (see p. 134) by inflation or with the aid of a
blunt probe.

Note that the common sheath which envelops the tendons of
the flexor digitorum sublimis and the flexor digitorum profundus
extends, from the distal part of the forearm, behind the transverse
carpal ligament, to the middle of the palm. Its proximal limit
is about 25 mm. above the transverse ligament. At its distal
limit, which is at the middle of the palm, practically at the same
level as the most distal part of the superficial volar arch, it
terminates, opposite the index, middle and ring fingers, in blunt
protusions on the tendons of the corresponding fingers, but on
its ulnar side it is prolonged into and is continuous with the
flexor digital sheath of the little finger, which is prolonged to the
base of the terminal phalanx of the little finger (Fig. 58). The
continuity is easily demonstrated, if inflation fails, by making
a small incision into the flexor sheath of the little finger and
passing a probe through the incision and along the sheath.

The synovial sheath of the flexor pollicis longus reaches the
same proximal level as the common flexor sheath, and it is pro-



FOREARM AND HAND



161



longed, distally, to the base of the terminal phalanx of the thumb.
The extent of this sheath can be investigated by a blunt probe
introduced through a small opening made opposite the first
phalanx of the thumb.

In some cases the mucous sheath which ensheaths the flexor tendons of
the fingers is divided into a medial and a lateral compartment by a fibrous
septum, and the lateral compartment may communicate with the sheath
of the flexor pollicis longus by means of a small aperture situated at
the proximal margin of the transverse carpal ligament.

Ligamentum Carpi Trans versum (O.T. Anterior Annular
Ligament). The transverse carpal ligament should now be

Pal mar is longus

Median nerve Transverse carpal ligament

I/lnar artery



Flexor pollicis longus .
Superficial volar artery, ;

Flexor carpi radialis -
Short muscles of thumb



Palmaris brevis
/ Ulnar nerve



Abductor pollicis
longus




Short muscles of
.little finger



Extensor polli
brev



Radial artery ^X&Cj
Extensor pollicis longus -

Extensor carpi radialis longus

Radial nerve, superficial
branch



Extensor carpi radialis brevis



jjfxf Extensor carpi ulnaris

*y^' 'Extensor digiti quinti
.. proprius

Dorsal branch of the ulnar nerve



Extensor digitorum communis and extensor
indicis proprius



FIG. 70. Transverse section through the Wrist at the level of the Distal
Row of Carpal Bones to show the Carpal Tunnel. The Tendons of the
Flexor Digitorum Sublimis, Flexor Digitorum Profundus, and Flexor
Pollicis Longus are seen within the Tunnel.

thoroughly examined before it is divided to expose the
portions of the flexor tendons, which lie behind it. It is a
thick, dense, fibrous band, which stretches across the volar
aspect of the concavity of the carpus, and converts it into an
osteo-fibrous tunnel for the passage of the flexor tendons into
the palm. On each side it is attached to the piers of
the carpal arch, viz., on the lateral side to the tubercle of
the navicular bone and the ridge of the greater multangular
bone, and on the medial side to the pisiform bone and the
hook of the os hamatum. Its proximal margin is continuous
with the deep fascia of the forearm, of which it may be
VOL. i 11



1 62 THE SUPERIOR EXTREMITY

considered to be a thickened part ; whilst distally it is con-
nected with the palmar aponeurosis.

Upon the volar surface of the transverse carpal ligament the
expanded tendon of the palmaris longus is prolonged distally
to the intermediate part of the palmar aponeurosis, whilst
from its sides some of the short muscles of the thumb and
little finger take origin. Close to its medial attachment the
ulnar artery and nerve find their way into the palm by pass-
ing superficial to it and deep to a more superficial fascial
band, the volar carpal ligament, which is attached on the
medial side to the pisiform and the hook of the os hamatum,
and on the lateral side to the volar surface of the transverse
carpal ligament,

The tunnel which the transverse carpal ligament forms
with the volar concavity of the carpus is transversely oval in
shape, and it opens distally into the intermediate compartment
of the palm. Through it pass the tendons of the flexor
digitorum sublimis, the flexor digitorum profundus, the tendon
of the flexor pollicis longus and the median nerve. The
relation of the tendon of the flexor carpi radialis to the
transverse carpal ligament is peculiar. It pierces the lateral
attachment of the ligament, and proceeds distally, in the
groove of the os multangulum majus, in a special compartment
provided with a special mucous sheath.

Dissection. Clean the fibrous sheaths of the flexor tendons
of the fingers and the thumb. They lie immediately subjacent
to the superficial fascia and the digital vessels and nerves, and
they bind the tendons to the volar aspects of the phalanges and
the interphalangeal joints.

Flexor Sheaths. Immediately subjacent to the skin,
the superficial fascia and the volar digital arteries and
nerves, lie the fibrous sheaths which bind the flexor tendons
to the volar surfaces of the phalanges, and to the volar
accessory ligaments of the metacarpo-phalangeal and inter-
phalangeal joints. Each fibrous sheath consists of a number
of parts of which the two strongest, the digital vaginal
ligaments, lie opposite the bodies of, and are attached to the
margins of, the first and second phalanges. Such strong bands
placed opposite the metacarpo-phalangeal and interphalangeal
joints would seriously interfere with their movements; therefore,
in those regions, weaker transverse bands, the annular liga-
ments, are formed. In addition, cruciate bands the cruciate



FOREARM AND HAND



163



ligaments are often found intervening between the annular
ligaments and the stronger portions of the sheaths. The



Digital synovial sheaths




Synovial sheath of
flex. poll, long



Ridge on os multangulum majn

Transverse carpal ligament



Pisiform



Tuberosity of navicular bone



' 1 1

ft ff



FIG. 71. The Synovial Sheaths of the Wrist and Hand. The positions oi
various incisions for the evacuation of pus are also shown.

i and 2. Incisions into the common palmar sheath, placed between the median and
ulnar nerves.

3. Incision uniting i and 2.

4. Incision into the proximal part of the sheath of flexor pollicis longus. It is placed
between the radial artery and the median nerve.

5. Incision into the distal part of the sheath of flexor pollicis longus.

6. Incision into the thenar space.

7. Incision over terminal phalanx.

8. 9 and 10. Incisions into the digital sheaths. They lie opposite the shafts of the
phalanges.

fibrous sheath, together with the phalanges and the volar
accessory ligaments of the metacarpo-phalangeal and inter-
i 11 a



1 64 THE SUPERIOR EXTREMITY

phalangeal joints, forms, in each finger, an osteo-fibrous
canal, in which are enclosed the tendons of the flexor
digitorum sublimis and the flexor digitorum profundus
together with their surrounding mucous sheath.

Leave the fibrous sheath of the middle finger intact
for revision, but open the other fibrous sheaths by longi-
tudinal incisions. They will be seen to be lined with a
mucous sheath which is reflected over the enclosed tendons
so as to give each a separate investment. Examine the extent
of each mucous sheath with the aid of a blunt probe. The
mucous sheath of the little finger has been seen to be a direct
prolongation from the common mucous sheath of the flexor
tendons ; the other three are distinct from that, but they are
carried proximally into the palm. They envelop the tendons
of the ring, index and middle fingers, as far as a line drawn
across the palm immediately proximal to the heads of the
metacarpal bones.

If the flexor tendons are raised from the phalanges, certain
mucous folds will be noticed connecting them to the bones.
These are termed the vincula tendinum. Two kinds of
them are distinguished, viz., vincula brevia and longa. In the
accompanying illustration (Fig. 72) the connections of these
may be seen. The vincula brevia are triangular folds
which connect the tendons, near their insertions, to the
volar aspect of the more proximal phalanx. The vincula
longa are not invariably present. They are placed more
proximally, and are narrow, weak strands which pass between
the tendons and the bones.

Insertions of the Flexor Tendons. The insertions of the
two flexor tendons can now be studied. On the volar side of
the first phalanx the tendon of the flexor sublimis becomes
flattened and folded round the subjacent cylindrical tendon
of the flexor profundus. It then splits into two parts,
which pass dorsal to the tendon of the flexor profundus,
and allow the latter to proceed onwards between them.
Dorsal to the deep tendon the two portions of the tendon
of the flexor sublimis fuse together, and then, again, they
diverge, to be inserted into the borders of the body of the
second phalanx. By this arrangement the flattened tendon
of the flexor sublimis forms a ring, or short tubular passage,
through which the tendon of the flexor profundus proceeds
onwards to the base of the ungual phalanx, into which it is



FOREARM AND HAND 165

inserted. In each of the four fingers the same arrangement
is found ; the tendon of the flexor sublimis is inserted by two
slips into the margins of the volar surface of the second
phalanx, whilst the tendon of the flexor profundus is in-
serted into the volar aspect of the base of the terminal
phalanx.

Dissection. Open the carpal tunnel by making a vertical
incision through the middle of the transverse carpal ligament.
Clean the mucous sheaths from the flexor tendons, and separate
the tendons from one another, but be careful not to injure the
lumbrical muscles which spring from the tendons of the flexor
digitorum profundus. Be careful also not to injure the nerves

Collateral interphalan- _-_ ^Flexor sheath

geal ligament-




lateral metacarpo-
phalangeal ligament

brevia Vincula longa

FIG. 72. Flexor Tendons of the Finger with Vincula tendinum.

of supply from the lateral two lumbricals. They are twigs from
the digital branches of the median nerve, and have already been
found. The nerves to the medial two lumbricals are from the
deep division of the ulnar nerve. They will be found at a later
stage of the dissection. Clean the lumbrical muscles and then
examine the arrangement of the flexor tendons and the origins
and insertions of the lumbrical muscles.

Flexor Tendons. The four tendons of the flexor sublimis
are arranged in pairs deep to the transverse carpal ligament;
those for the little and the index fingers lie dorsal to those
for the ring and middle fingers. Of the tendons of the
flexor profundus, only that for the index finger is distinct and
separate ; the other three, as a rule, remain united until they
emerge from under cover of the distal border of the transverse
carpal ligament.

In the intermediate compartment of the palm the -flexor
tendons diverge from each other, and two, viz., one from the
flexor sublimis, and one from the flexor profundus, go to each
of the four fingers. From the tendons of the flexor profundus
the lumbrical muscles take origin, and those muscles, and the
volar digital nerves and arteries, will be seen occupying the
i 11 &



1 66 THE SUPERIOR EXTREMITY

intervals between the tendons as they approach the roots of
the fingers.

In the fingers the two flexor tendons run distally, upon
the volar aspects of the phalanges, and are held in position
by the flexor sheaths, which have already been studied.

The tendon of ti\e flexor pollicis longus occupies the lateral
part of the tunnel, and, gaming the palm, turns laterally to
reach the terminal phalanx of the thumb.

Tendon of the Flexor Pollicis Longus. The tendon of
the long flexor of the thumb proceeds distally, in the interval
between two of the short muscles of the thumb (viz., the
superficial head of the flexor pollicis brevis and the oblique
part of the adductor pollicis), and also in the interval between
the two sesamoid bones which play upon the head of the
metacarpal bone. At the base of the proximal phalanx it
enters a fibrous flexor sheath constructed upon a similar
plan to those of the fingers, and passes along it to the base
of the terminal phalanx, into which it is inserted. The
mucous sheath which surrounds the tendon during its
passage through the carpal tunnel is continuous with the
sheath which invests the tendon in front of the phalanges.

Mm. Lumbricales. The lumbrical muscles are four slender
fleshy bellies which arise from the tendons of the flexor
digitorum profundus as they traverse the palm. The first
lumbrical arises from the lateral side of the tendon for the
index finger ; the second lumbrical springs from the lateral
border of the tendon for the middle finger ; whilst the third
and fourth lumbricals take origin from the adjacent sides of
the tendons between which they lie (viz., the tendons for
the middle, ring, and little fingers). The little muscles pass
distally, and end in delicate tendons on the lateral sides of
the fingers. Each tendon is inserted into the lateral margin
of the expansion of the extensor tendon, which lies upon the
dorsal aspect of the proximal phalanx.

Dissection. Divide the flexor digitorum profundus in the
forearm, and turn the distal part towards the fingers. As the
tendons and the lumbrical muscles which are attached to them
are raised, secure the fine twigs of supply which pass to the
medial two lumbricals from the deep division of the ulnar nerve.
They are easily found if ordinary caution is observed. The
deep volar arch and the deep division of the ulnar nerve are now
exposed. Clean both the arch and the nerve, and trace the
branches of the nerve to the interossei muscles and to the adductor
pollicis and the deep head of the flexor pollicis brevis. Then



FOREARM AND HAND 167

examine the relations of the deep volar arch, and the deep
division of the ulnar nerve.

Arcus Volaris Profundus (O.T. Deep Palmar Arch).
Two arteries take part in the formation of the deep volar
arch, the radial and the profunda branch of the ulnar.
The radial, which plays the chief part, enters the palm through
the proximal end of the first interosseous space, between the
two heads of the first dorsal interosseous muscle, and in the
present stage of dissection it is seen appearing through the
cleft between the oblique and transverse parts of the adductor
pollicis. The arterial arcade formed by its union with the
profunda branch of the ulnar artery lies across the metacarpal
bones, immediately distal to their bases^ and across the inter-
osseous muscles in the intervening interosseous spaces. The
deep arch is, therefore, about a finger's breadth proximal to
the superficial volar arch, but it is in a much deeper plane,
for it is separated from the superficial volar arch by the
flexor tendons of the fingers and their mucous sheath,
the lumbrical muscles, branches of the median nerve and the
flexor digiti quinti brevis. The convexity of the deep arch,
which is less marked than that of the superficial arch, is
directed towards the fingers, and in its concavity lies the



Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 17 of 44)