Anatomic variations of the musculocutaneous nerve in the arm.

To determine the course and anatomic relationships of the musculocutaneous nerve in the arm, we dissected 54 cadaver arms and measured the length of any interconnection between the musculocutaneous nerve and the median nerve (36% of dissections; mean, 1.77 cm) and the distance from the coracoid process to (1) the musculocutaneous nerve (mean, 0.46 cm distal); (2) the median nerve (mean, 1.91 cm distal); (3) the musculocutaneous nerve's entrance to and exit from the coracobrachialis muscle (mean, 4.99 cm and 7.55 cm, respectively); and (4) the musculocutaneous nerve's entrance into the biceps muscle (mean, 11.66 cm). The high percentage of anomalies found emphasizes the complexities and irregularities of this anatomic region with regard to surgical approaches.