ll

f
oCL
EL

co
(po
a

UPPER LIMB

from index finger and two digital veins from

thumb to form cephalic vein. It runs proximally

inthe anatomical snuff box, curves, rormd the lateral

border of wrist to come to front of forearm. In a

similar manner the medial end of the arch joins

with one digital vein only from medial side of little

finger to form basilic vein. It also curves round

the medial side of wrist to reach front of forearm.

These metacarpal veins may unite in different

ways to form a dorsal venous plexus.

b. Cutaneous neraes: These are superficial branch of

radial nerve and dorsal branch of ulnar nerve. The

nail beds and skin of distal phalanges of 3l/zlateral

nails is supplied by median nerve andlr/z medial

nails by ulnar nerve. The superficial branch of

radial nerve supplies lateral half of dorsum of

hand with two digital branches to thumb and one

to lateral side of index and another common

digital branch to adjacent sides of index and

middle fingers.

Dorsal branch of ulnar supplies medial half of

dorsum of hand with proper digital branches to

medial side of little finger; two common digital

branches for adjacent sides of little and ring fingers

and adjacent sides of ring and middle fingers.

c. Dorsal carpal arch: It is formed by dorsal carpal

branches of radial and ulnar arteries and lies close

to the wrist joint. The arch gives three dorsal

metacarpal arteries which supply adjacent sides

of index, middle; ring and little fingers. One digital

artery goes to medial side of little finger. The arch

also gives branches to the dorsum of hand.

3 Spaces on dorsum of hand:

There are two spaces on the dorsum of hand:

a. Dorsal subcutaneous space, lying just subjacent

to skin. Skin of dorsum of hand is loose can be

pinched and lifted off.

b. Dorsal subtendinous space lies deep to the

extensor tendons, between the tendons and the

metacarpal bones (Fig. 9.52).

4 DeE fnscia: The deep fascia is modified at the back

of hand to form extensor retinaculum.

Exlensor Retinoculum

The deep fascia on the back of the wrist is thickened to

form the extensor retinaculum which holds the extensor

tendons in place. It is an oblique band, directed

downwards and medially. It is about 2 cm broad

vertically (Fig. 9.55).

Affmeftrnes*fs

Laterally: Lower part of lhe anterior border of the

radius.

Medially:

i. Styloid process of the ulna.

ii. Triquetral.

iii. Pisiform.

#*mrup*rfmer:fs

The retinaculum sends down septa which are attached

to the longitudinal ridges on the posterior surface of

the lower end of radius. In this way, 6 osseofascial

compartments are formed on the back of the wrist.

The structures passing through each compartment,

from lateral to the medial side, are listed in Table 9.8

and Fig. 9.56.

Each compartment is lined by a synovial sheath,

which is reflected onto the contained tendons.

SUPERFICIAL MUSCLES

There are seven superficial muscles on the back of the

forearm:

1 Anconeus

2 Brachioradialis (Fig. 9.57)

3 Extensor carpi radialis longus

(^4) Extensor carpi radialis brevis
5 Extensor digitorum (Fig 9.55).
6 Extensor digiti minimi
7 Extensor carpi uhraris.
All the seven muscles cross the elbow joint. Most of
them take origin (entirely or in part) from the tiP of the
lateral epicondyle of the humerus.
These muscles with their nerve supply and actions
are described in Tables 9.9 and9.70.
Additionol Poinls
1 The extensor digitorum and extensor indicis pass
through the same compartment of the extensor
retinaculum, and have a corilnon symovial sheath.
2 The four tendons of the extensor digitorum emerge
from undercover of the extensor retinaculum and fan
out over the dorsum of the hand. The tendon to the
index finger is joined on its medial side by the tendon
of the extensor indicis, and the tendon to the little
finger is joined on its medial side by the two tendons
of the extensor digiti minimi.
3 On the dorsum of the hand, adjacent tendons are
variably connected together by three intertendinous
connections directed obliquely downwards and
laterally. The medial connection is strong; the lateral
connection is weakest and may be absent.
The four tendons and three intertendinous
connections are embedded in deep fascia, and
together form the roof of the subtendinous
(subaponeurotic) space on the dorsum of the hand.