The musculocutaneous (MC) nerve is a sensori-motor nerve that originates from the lateral cord of the brachial plexus at the infero-lateral margin of the minor pectoral muscle
It follows the axillary artery for a short distance before it deviates laterally and pierces the coracobrachial muscle or enters the fascial plane between this muscle and the short head of the biceps brachii muscle
Often the MC nerve enters this fascial plane directly from medial to lateral without piercing the coracobrachial muscle
Musculocutaneous nerve (cyan arrows), coracobrachial muscle (green asterix), teres major muscle (blue asterix), minor pectoral muscle (cyan asterix) The short head of the biceps brachii muscle has been removed to expose the musculocutaneous nerve
