The musculocutaneous (MC) nerve origins from the lateral cord of the brachial plexus. Proximal to the lower border of the axilla (= the lower margin of the teres major muscle) the trajectory of the MC nerve deviates from the axillary artery and veins and the nerve exits the axilla by piercing the coracobrachialis muscle and descends and ramifies in the fascial plane between the coracobrachialis muscle and the short head of the biceps brachii muscle
This means that the MC nerve has to be blocked separately in the fascial plane between the coracobrachialis muscle and the short head of the biceps brachii muscle with the axillary block
The short head of the biceps muscle has been removed exposing the long head of the biceps (white asterix) and the piercing of the coracobrachialis muscle (green asterix) by the musculocutaneous nerve (magenta arrows)
