Musculocutaneous nerve

The musculocutaneous nerve, located in the arm, extends out of the lateral cord of the brachial plexus, which lies opposite the pectoralis major's lower edge. It enters the coracobrachialis muscle before passing obliquely between the between the brachialis and the biceps brachii to the arm's lateral side. It penetrates the deep fascia slightly above the elbow, entering at a point that lies lateral to the biceps brachii tendon. The musculucotaneous nerve continues down the forearm where it becomes the lateral cutaneous nerve. This nerve is prone to irregularities. Instead of passing through the coracobrachialis, sometimes it passes under the biceps brachii. Normally, after running down its median, the fibers of the musculocutaneous nerve leave it for their proper trunks; however, the median of the nerve sometimes sends a nerve branch that joins it, meaning it travels in the opposite direction. The musculocutaneous nerve can be damaged if it becomes trapped between the brachialis and the biceps aponeurosis, or if it is stretched in an arm dislocation. Prolonged damage to the nerve, usually due to weight lifting, can lead to a loss of muscle-flexing strength or supination of the forearm; avoiding bicep exercises is the best treatment.

Written and medically reviewed by the Healthline Editorial Team
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In Depth: Musculocutaneous nerve

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