Unusual insertion of the coracobrachialis muscle to the brachial fascia associated with high division of brachial artery.

Anatomical variations of the coracobrachialis muscle (CBM) are common. We detected an abnormal form of the CBM of the left arm during human cadaver dissection. The CBM originated from the tip of the coracoid process of the scapula and divided into muscular and musculo-aponeurotic bellies. The muscular belly inserted into the middle of the anteromedial surface of the humerus, which is the normal anatomic insertion point of the CBM. The musculo-aponeurotic belly inserted into the medial intermuscular septum as well as the brachial fascia, creating a tunnel for the passage of the brachial artery. Inside the tunnel, the brachial artery bifurcated into the radial and ulnar arteries. No abnormality of the CBM, the brachial artery, or the median nerve was detected in the contralateral arm. The phylogenic, ontogenic, functional, and clinical importance of this variant muscle is described. Knowledge of such variations is of considerable importance during invasive and non-invasive investigative procedures or orthopedic, reconstructive, or surgical procedures.