Human Anatomy Vol 1

UPPEB LIMB

Components

The front of the forearm presents the following

components for study.

L Eight muscles, five superficial and three deep.

2 Two arteries, radial and ulnar.

3 Three nerves, median, ulnar and radial.

These structures can be better understood by

reviewing the long bones of the upper limb and having

an articulated hand by the side.

SUPERFICIAL MUSCLES

The muscles of the front of the forearm may be divided

into superficial and deep groups.

There are five muscles in the superficial group. These

are the pronator teres, the flexor carpi radialis, the

palmaris longus, the flexor carpi uhraris and the flexor

digitorum superficialis (Tables 9.7 and9.2).

Common Flexor Origin

All the superficial flexors of the forearm have a common

origin from the front of the medial epicondyle of the

humerus. This is called the common flexor origin.

Additionol Feolures of Superficiol Muscles

"L Pronator teres:Pronator teres comprises a big humeral

and a smaller ulnar head. Between the two heads

median nerve leaves the cubital fossa. Deep to the

two heads exits ulnar artery from cubital fossa into

the front of forearm. It forms medial boundary of

the cubital fossa. It is the pronator of forearm (seeFig.

B.1e).

2 Flexor carpi radialis; It passes through a separate deep

compartment of the flexor retinaculum.

Flexor carpi radialis gets inserted into anterior

aspects of bases of second and third metacarpal

bones.

It is easily seen and is a guide to radial pulse which

lies lateral to the tendon (Fig. 9.6).

3 Palmarislongus: Palmaris longus continues as palmar

aponeurosis into the palm to protect the nerves and

vessels there. Its tendon lies superficial to flexor

retinaculum.

4 Flexor carpi ulnaris: It is inserted into pisiform bone.

Pisiform is a sesamoid bone in this tendon.

5 Flexor digitorum superficialis; Flexor digitorum

superficialis comprises the humeroulnar and radial

heads. The two heads of the muscle are joined by a

fibrous arch. Median nerve and ulnar artery pass

downwards deep to the fibrous arch (Fig. 9.4).

DEEP MUSCLES

Deep muscles of the front of the forearm are the

flexor digitorum profundus, the flexor pollicis longus

and the pronator quadratus and are described in

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Muscle

1. Pronator teres


2. Flexor carpi radialis


3. Palmaris longus


4. Flexor digitorum
   superficialis
   (Figs 9.4 and 2.38a)
   . Humeroulnar head

Radial head

5. Flexor carpi ulnaris
   . Humeral head
   . Ulnar head

Muscle

1. Pronator teres


2. Flexor carpi radialis


3. Palmaris longus


4. Flexor digitorum superficialis
   (Figs 9.4 and 9.5)


5. Flexor carpi ulnaris

Table 9.1: Attachment of the superficial muscles

Origin lnsertion

Medial epicondyle of humerus

Medial epicondyle of humerus

Medial epicondyle of humerus

Medial epicondyle of humerus; medial

border of coronoid process of ulna

Anterior oblique line of shaft of radius

Medial epicondyle of humerus

Medial aspect of olecranon process and

posterior border of ulna

Middle of lateral aspect of shaft of radius

Bases of second and third metacarpal bones

Flexor retinaculum and palmar aponeurosis

Muscle divides into^4 tendons. Each tendon

divides into 2 slips which are inserted on

sides of middle phalanx of 2nd to 5th digits

Pisiform bone; insertion prolonged to hook of

the hamate and base of fifth metacarpal bone

(see Fig. 2.38a)

Actions

Pronation of forearm

Flexes and abducts hand at wrist joint

Flexes wrist joint

Flexes middle phalanx of fingers and assists

in flexing proximal phalanx and wrist joint

Flexes and adducts the hand at the wrist ioint

Table 9.2: Nerve supply and actions of the superficial muscles

Nerue supply

Medion Nerve

Ulnor Nerve

Median nerve

Median nerve

Ulnar nerve