A variation of Musculocutaneous nerve without piercing the coracobrachialis muscle while communicating to the median nerve: A case report and literature review

Abstract

HighlightsThe Musculocutaneous nerve is one of the terminal branches of the lateral cord (C5– C7) in the axilla that runs downwards by piercing the coracobrachialis muscle, then enters to anterior compartment of the arm.The Median nerve is one of the three major nerves of the forearm and hand which is derived from the medial and lateral cords of the brachial plexus in the axillary region that has not any branch in the arm exceptionally in some cases may has a communication branch with the Musculocutaneous nerve.

Bilateral variations of median nerve formation and endpoint variation of brachiales veins

“…It was reported that the brachial plexus is a variative part of the peripheral nerve system. The musculocutaneous nerve variations, which have an incidence of 6.25% according to the literature, are mainly divided into two groups: Its absence and the presence of a communication between the musculocutaneous and median nerves [3].…”

“…The presence of these and similar neural and vascular variations is important in respect of the possible nerve injuries, which may be caused by a piercing or cutting trauma in the upper extremity. coracobrachialis muscle and ends in the sensorial branch or in the lateral side of the forearm after innervating these three muscles [3].…”

“…Nasrabadi et al dissected an Iranian male cadaver and observed an unexpectedly thin musculocutaneous nerve, which originated from the lateral cord before piercing the muscle on the ventral face of the coracobrachialis muscle and gave a communicating branch to the median nerve [3].…”

“…The divisions, which are formed as a result of the splitting of the trunks in the posterior triangle of the neck, join again in the axilla and form the cords named according to the neighbourhood with the axillary artery. Thus, the lateral cord is formed by the ventral division of the upper and middle trunks; medial cord by the ventral division of the lower trunk and posterior by the posterior division [1][2][3]. The peripheral nerves, which are responsible for the sensorial and motor innervation of the upper extremity, originate from the brachial plexus.…”

“…The median nerve is usually formed by two separate roots originating from the lateral and middle cord and it passes through the arm without giving branches except for the branch, which innervates the brachial artery, and participates in the innervation of the forearm and the hand [3,6,9].…”