Human Anatomy Vol 1

(mdmrcog) #1
Lateral

Radial nerve
Biceps brachii tendon
Brachial artery
Median nerve

Radial artery

Deep and
superficial
heads of
pronator teres

Median nerve

Fig.9.11: Relations of the median nerve in right cubital fossa,
and its entry into the forearm


posterior ulnar recurrent artery arises lower than
the anterior and ends by anastomosing with the
superior ulnar collateral artery behind the medial
epicondyle (see Fig. 8.11).
2 The cofltmon interosseous nrtery (abottt 1 cm long)
arises just below the radial tuberosity. It passes
backwards to reach the upper border of the
interosseous membrane, and end by dividing into
the anterior and posterior interosseous arteries.
The anterior interosseous artery is the deepest
artery on the front of the forearm. It accompanies
the anterior interosseous nerve.
It descends on the surface of the interosseous
membrane between the flexor digitorum
profundus and the flexor pollicis longus (Fig. 9.5).
It pierces the interosseous membrane at the
upper border of the pronator quadratus to enter
the extensor compartment.
The artery gives muscular branches to the deep
muscles of the front of the forearm, nutrient
branches to the radius and ulna and amedian artery
which accompanies the median nerve.
Near its origin, the posterior interosseous artery
gives off the interosseous recurrent artery which
runs upwards, and ends by anastomosing with
middle collateral artery (posterior branch of
profunda brachii artery) behind the lateral
epicondyle.
3 Muscular branches supply, the medial muscles of
the forearm.
4,5 Palmar and dorsal carpal branches take part in the
anastomoses round the wrist joint. The palmar
carpal branch helps to form the palmar carpal arch.

FOREARM AND HAND

The dorsal carpal branch arises just above the
pisiform bone, winds backwards deep to the
tendons, and ends in the dorsal carpal arch.
This arch is formed medially by the dorsal
carpal branch of the ulnar artery, and laterally by
the dorsal carpal branch of the radial artery.

Dissection

Median nerve is the chief nerve of the forearm. lt enters
the forearm by passing between two heads of pronator
teres muscle. lts anterior interosseous branch is given
off as it is leaving the cubital fossa. ldentify median
nerve stuck to the fascia on the deep surface of flexor
digitorum superficialis muscle. Thus, the nerve lies
supedicial to the flexor digitorum profundus (Fig. 9.a).
Dissect the anterior interosseous nerve as it lies on
the interosseous membrane between flexor pollicis
longus and flexor digitorum profundus muscles (Fig. 9.a).
ldentify the ulnar nerve situated behind the medial
epicondyle. Trace it vertically down till the flexor
retinaculum (Fig. 9.1 0).
Trace the radial nerve and its two branches in the
lateral part of the cubital fossa. lts deep branch is mus-
cular and supedicial branch is cutaneous (Fig. 9.a).

Nerves of the front of the forearm are the median,
ulnar and radialnerves. Theradial and ulnarnervesrun
along the margins of the forearm, and are never crossed
by the correspondingvessels which gradually approach
them. The ulnar artery, while approaching the ulnar
nerve, gets crossed by the median nerve (Fig. 9.10).

MEDIAN NERVE
Median nerve is the main nerve of the front of the
forearm. It also supplies the muscles of thenar eminence
(Fig. e.10).
The median nerve controls coarse movements of the
hand, as it supplies most of the long muscles of the front
of the forearm. It is, therefore, called the 'labourer's
nerve'.

Course
Median nerve lies medial to brachial artery and enters
the cubital fossa. It is the most medial content of cubital
fossa (Fig. 9.11). Then it enters the forearm to lie
between flexor digitorum superficialis and flexor
digitorum profundus. It lies adherent to the back of
superficialis muscle. Then it reaches down the region
of wrist where it lies deep and lateral to palmaris longus
tendon. Lastly it passes deep to flexor retinaculum
through carpal tunnel to enter the palm (Fig.9.12).

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