An anomalous muscle in the distal half of the arm.

During dissection an anomalous muscle was found on the medial aspect in the distal half of one left upper extremity. This muscle arose from the humerus between the m. coracobrachialis and the m. brachialis, passed obliquely across the front of the brachial artery and median nerve and blended with the common origin of the forearm flexor muscles. It does not appear to be an additional head of the biceps brachii or the brachialis muscles. The existence of this anomalous muscle should be kept in mind in a patient presenting with a high median nerve palsy together with symptoms of brachial artery compression.