6.Flexor Digitorum Superficialis 7.Ulnar Artery 8.Ulnar Nerve 9. Flexor Carpi Ulnaris 1.Brachioradialis 2.Superficial Radial n. 3.Radial Artery 4.Flexor Carpi Radialis 5. Median Nerve

Nerves of the Anterior Compartment

---The median nerve leaves the cubital fossa by passing between the two heads of pronator teres. ---It continues downward adherent to the posterior surface of the flexor digitorum superficialis.

----At the wrist it emerges between the lateral margin of the tendons of flexor digitorum superficialis and the tendon of flexor carpi radialis. Here it lies posterior to the palmaris longus tendon. ----The median nerve enters the palm by passing posterior to the flexor retinaculum

1. Muscular branches in the cubital fossa to the pronator teres, the flexor carpi radialis, the palmaris longus, and the flexor digitorum superficialis. 2. Articular branches to the elbow joint.

3. Anterior interosseous nerve, which arises as it emerges from between the two heads of the pronator teres muscle. It runs down on the anterior surface of the interosseous membrane. Give branches from to the flexor pollicis longus, the lateral half of flexor digitorum profundus, and the pronator quadratus. 4. Palmar cutaneous branch, Which passes to the skin over the lateral part of the palm.

The ulnar nerve enters the forearm from behind the medial epicondyle of the humerus. Note that it crosses the medial ligament of the elbow joint and passes between the two heads of the flexor carpi ulnaris..

The nerve pass downward between the flexor carpi ulnaris and the flexor digitorum profundus muscles. At the wrist observe that the nerve lies between the tendons of the flexor carpi ulnar and the flexor digitorum superficialis muscles. The ulnar nerve enters the palm lateral to the pisiform bone, anterior to the flexor retinaculum.

1. Muscular branches to the flexor carpi ulnaris and to the medial half of the flexor digitorum profundus. 2. Articular branches to the elbow joint.

3. Palmar cutaneous branch, which arises in the middle of the forearm and supplies the skin over the hypothenar eminence. 4. Dorsal branch, or posterior cutaneous branch, which is large and passes medially between the tendon of flexor carpi ulnaris and the ulna and is distributed on the posterior surface of the hand and fingers.

Definition: portion of the posterior fascial compartment of the forearm that includes the “lateral wad” muscles; brachioradialis and extensores radiales.

The posterior compartment of the forearm contains 11 muscles, divided into deep and superficial layers. Superficial  brachioradialis  extensor carpi radialis longus  extensor carpi radialis brevis  extensor digitorum  extensor digiti minimi  extensor carpi ulnaris Deep  supinator  extensor pollicis longus  extensor pollicis brevis  abductor pollicis longus  extensor indicis   The aconeus is sometimes considered part of the posterior compartment of the forearm rather than in the posterior compartment of the arm Blood supply anterior and posterior interosseous arteries (branches of the ulna artery via the common ulna artery Nerve supply all muscles in the extensor compartment are supplied by the radial nerve

 Seven superficial and five deep muscles occupy the posterior forearm.  The superficial group arises mostly from the posterior aspect of the lateral epicondyle of the humerus by a common tendon.  The muscles are supplied by (1) the radial nerve or (2) its deep branch, which continues as the posterior interosseous nerve

There are seven muscles in this layer, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris and anconeus. Apart from the anconeous and brachioradialis, all continue as tendons into the hand, and can also be referred to as extrinsic hand muscles

Attachments: Originates from the proximal surface of the supra epicondylar ridge of the humerus, and attaches to the distal end of the radius, just before the radial styloid process Actions: Flexes at the elbow Innervation: Radial nerve

These extensor muscles are found laterally on the forearm. The extensor carpi radialis brevis lies deep to the longus. Attachments: The ECRL originates more proximally, from supracondylar ridge, while the ECRB originates from the lateral epicondyle. Their tendons attach to the II and III metacarpal bones Actions: Extension and abduction of the wrist Innervation: Radial nerve

The main extensor of the fingers, this muscle makes up most of the posterior surface of the forearm. Attachments: Originates from the lateral epicondyle. In the distal part of the forearm, the muscle tendon splits into four, and inserts into the extensor hood of each finger. Actions: Extends medial four fingers at the MCP and IP joints Innervation: Radial nerve

A fibrous sheet on the back of each finger is known as the extensor expansion, or dorsal aponeurosis, and it contains a hood of transverse fibers. The expansion is penetrated by the extensor tendon, which then divides into three slips: a central slip to the base of the middle phalanx and two collateral bands, which, fused with expansions from the interossei and lumbricals, unite and proceed to the base of the distal phalanx.

This mucles lies medially and slightly deep to the extensor digitorum. Attachments: Originates from the lateral condyle of the humerus, and attaches, with the extensor digitorum tendon, into the extensor hood of the little finger Actions: Extends the little finger, and contributes to extension at the wrist Innervation: Radial nerve

This is found on the medial side of the forearm. Attachments: Originates from the lateral condyle, and attaches to the base of metacarpal V. Actions: Extension and adduction of wrist Innervation: Radial Nerve

 The most medial of the muscles in the extensor compartment of the forearm. It is blended with the fibres of the triceps brachii, and can be hard to distinguish from it. Attachments: Originates from the lateral epicondyle, and attaches to the posterior and lateral part of the olecrannon Actions: Moves the ulna during pronation and extends at the elbow joint Innervation: Radial Nerve