Muscular Branches of Musculocutaneous Nerve (Left)

Description

Musculocutaneous nerve is a branch of the lateral cord of the brachial plexus, arising at the lower border of pectoralis minor muscle in the axilla. It receives nerve fibers from the C5—C7 cervical spinal segments (or roots).

The nerve then leaves the axilla and usually enters the front of the arm by piercing the coracobrachialis muscle. In the arm, it runs downwards and laterally between the biceps brachii superficially and brachialis deeper to reach the lateral side of the tendon of the biceps. It ends by piercing the fascia slightly above the bend of the forearm to provide cutaneous innervation for the lateral forearm (Rea, 2016).

The musculocutaneous nerve innervates the following muscles of the flexor compartment of the arm region:

—coracobrachialis (as it pierces the muscle to enter the front of the arm);

—the short and long heads of biceps brachii;

—the lateral part of brachialis muscles (as the nerve descends, sandwiched between these two muscles to reach the lateral side of the tendon of biceps).