Muscle Origin Insertion Innervation Action Image

Muscles of the posterior compartment of the : - ✓ Most originates from Common extensor origin lateral epicondyle ✓ All supplied by the radial ✓ Supply: posterior and anterior interosseous arteries ✓ Most Extend wrist joint ✓ Muscles are arranged in 3 groups: - 1) LATERAL 2) SUPERFICIAL 3) DEEP

We have 3 positions for the hand as illustrated in the image below

Contents of the Lateral Fascial Compartment of the Forearm

Lateral Stabilizes the elbow supracondylar joint during flexion Base of styloid ridge Brachioradialis process of Radial Nerve lateral rotates forearm to radius epicondyle of the midprone the humerus position

Posterior Lateral surface of base extensor carpi Extends and abducts supracondylar of second Radial Nerve radialis longus hand at wrist joint ridge of humerus metacarpal bone

Both bracioradialis and extensor carpi radials longus are supplied by The radial nerve before it divides which means if the upper part of the radial nerve (before it divides) got damaged both muscles will be effected, but if the injury was after the nerve divided nothing will happen to these two muscles.

The Superficial group Posterior the lateral surface of base Nerve supply: Extensor carpi Extends and abducts epicondyle of of third deep branch of radialis brevis hand at wrist joint the humerus metacarpal the radial nerve bone Nerve supply: by the posterior Extensor interosseous *It forms four digitorum nerve which is Extends the index, , each of the continuation middle, ring, and (It is the major from the lateral which passes of the deep little fingers; extensor of the epicondyle of four fingers into a finger branch of the the humerus (index, middle, radial nerve can also extend the ring, and little (see the pic that has * in the next page) after it emerges wrist fingers)) from the supinator muscle Extensor Posterior the lateral expansion of interosseous Extensor digiti Extends the little epicondyle of little finger nerve minimi finger the humerus (Dorsal hood of (not mentioned in the slides, I think the doc the little finger) just forgot to add it)

Lateral Base of fifth Posterior Extensor carpi Extends and adducts epicondyle of metacarpal interosseous ulnaris the wrist humerus bone nerve

Abduction of the ulna Lateral olecranon Nerve supply: in pronation; Anconeus epicondyle of process of ulna Radial nerve accessory extensor of humerus the elbow joint

❖ Blood supply: Posterior and anterior interosseous arteries ❖ Nerve supply: Deep branch of the radial nerve ❖ These muscles possess a common of origin, which is attached to the lateral epicondyle of the humerus ❖ Because most the muscles of posterior compartment are attached to the lateral epicondyle it may develop Chronic lateral epicondylitis of the elbow leading to pain and tenderness. It is a frequent complaint among tennis players *

Deep group

Front and lateral and posterior Nerve supply: Supination the *Supinator surfaces of the Deep branch of forearm upper 1/3 of the Radial Nerve radius.

Nerve supply: Base of the 1st Abductor pollicis posterior Abducts and extends Metacarpal longus interosseous thumb bone nerve.

Not required Base of the Nerve supply: Extends Extensor pollicis proximal posterior Metacarpophalangeal brevis phalanx of the interosseous joint of the thumb. thumb. nerve. Nerve supply: Base of the Extensor pollicis posterior Extends the distal distal phalanx of longus interosseous phalanx of the thumb the thumb nerve.

Its tendon joins Nerve supply: the extensor posterior Extends all the joints Extensor indicis expansion of the interosseous of the index finger index finger nerve

❖ Blood supply: Posterior and anterior interosseous arteries ❖ Nerve supply: Deep branch of the radial nerve

*

Done by Waseem, Dr Amjad shatarat’s slides