Variation in the Origin of Pronator teres

Pronator teres generally originated by the two heads namely humeral and ulnar. The humeral head is the larger of the two, begins above the medial epicondyle on the medial supracondylar ridge and the common flexor tendon. The ulnar head originats below the elbow on the medial side of the coronoid process of the ulna. The Anatomical variations already known include the absence of ulnar head, additional slips from the medial intermuscular septum, from the Biceps, from the Brachialis and occasional hypertrophy of the muscle mass.

In the present study of routine anatomical dissection of the right upper extremity of an adult male cadaver, the pronator teres muscle was found to have an abnormal origin by third head. This third head took its origin from fibers and fascia covering the flexor carpi radialis muscle. The three heads come together, cross the forearm diagonally, and insert halfway down the lateral surface of the radius via a tendon. Such variations have clinical implications and therefore while managing patients with neurogenic pain in the wrist or a median nerve paralysis with symptoms of lower brachial artery or brachial vein compression, these anatomical variations should always be born in mind.