Synonym: ulnar hand extensor
German: Musculus extensor carpi ulnaris
Some authors describe it as a two-headed muscle, since it inserts at the ulna and at the humerus. Others list it as single-headed muscle.
The humeral head of the extensor carpi ulnaris muscle has its origin at the lateral epicondyle of the humerus - between the anconeus muscle and the extensor digitorum muscle. The ulnar head has its origin at the dorsal edge of the ulna. Moreover, the muscle has areas of origin at the antebrachial fascia.
The muscle pases along the ulna into distal direction and ends in a long tendon, which draws into a hollow between the head and the styloid process of the ulna to the wrist. It passes further into distal direction below the extensor retinaculum to finally insert at the base of the 5th metacarpal bone, marked by bony tubercle.
The flexor carpi ulnaris muscle effects an ulnar abduction and an extension (dorsal flexion) in the wrist. According to some authors, the dorsal flexion in the radiocarpal joint and the palmar flexion in the mediocarpal joint reciprocally cancel each other out, so that the muscle essentially has a purely abducting effect.
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