Anatomy
Origin:
First head: Lateral epicondyle of humerus via the common extensor tendon.
Second head: Posterior border of ulna.
Insertion:
Medial aspect of base of fifth metacarpal
Key Relations:
One of the four muscles in the superficial posterior compartment of the forearm.
Functions
-Extends the hand at the wrist joint.
-Adducts the hand at the wrist joint (ulnar deviation) particularly when acting together with flexor carpi ulnaris.
E.g. as in accelerating a motorbike.
Supply
Nerve Supply:
Posterior interosseous nerve (C7,C8) (continuation of deep branch of the radial nerve).
Blood Supply:
Ulnar artery.
Clinical
Rheumatoid arthritis patients often suffer synovitis of the tendon, believed to be a result of rubbing of the tendon off the styloid process of the ulna as the hand and forearm are pronated and supinated.
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