A Cadaveric Study on the Anatomic Variations of the Musculocutaneous Nerve in the Infraclavicular Part of the Brachial Plexus

Background and Objectives:The Musculocutaneous nervearises from the lateral cord of the brachial plexus, passes inferolaterally and then pierces through the coracobrachialis after supplying it, descends between the biceps and the brachialis, sending branches to both and continues as the lateral cutaneous nerve of the forearm. Variations in the origin, course, branching pattern, termination and the connections of the musculocutaneous nerve are not uncommon. These variations have clinical significance during surgical procedures, in the brachial plexus block and in diagnostic clinical neurophysiology. Methods: A detailed study was carried out on 50 upper limbs by using 25 embalmed cadavers. Dissection of the infraclavicular part of the brachial plexus was done. The variations in the origin, number and course, and their correlations to the coracobrachialis were noted. Results: Absence of the musculocutaneous nerve was noted in 6% of the limbs. The nerve was found to not pierce the coracobrachialis in 6% of the limbs. In 2% of the limbs, the nerve was found to rejoin the median nerve after piercing the coracobrachialis. Interpretation and Conclusion: The observations show that the musculocutaneous nerve has significant variations and that these variations have clinical significance in post traumatic evaluations and in the exploratory innervations of the arm for peripheral nerve repair.