Unusual pectoralis major muscle: the chondroepitrochlearis.

Presented herein is a case of an extremely rare muscle in the pectoral region. It involved an accessory muscular slip originating from the pectoralis major and inserting onto the medial epicondyle of the humerus and the medial intermuscular septum. According to the literature this muscle is defined as chondroepitrochlearis. The arterial and nervous supply to the muscle came from the lateral thoracic artery and the medial pectoral nerve, respectively. Clinical considerations of such a variation include ulnar nerve entrapment and functionally limited abduction of the humerus.