Loss of flexion of shoulder* Flexion at shoulder is done by major muscles like pectoralis major, anterior fibres of deltoid, which are intact here. Musculocutaneous nerve (MCN)originates from the lateral cord of the brachial plexus of nerves. It pierces the coracobrachialis muscle and gives off branches to the muscle, as well as to brachialis and biceps brachii, the chief flexors at elbow joint. Coraco-brachialis is a flexor at shoulder joint Biceps brachii is a powerful supinator, hence supination is weakened. MCN terminates as the lateral cutaneous nerve of the forearm.