Quick Facts
Origin: Lateral cord of brachial plexus (C5—C7).
Course: Accompanies third part of axillary artery in lower part of axilla, pierces coracobrachialis to enter anterior arm and descends between biceps brachii and brachialis muscle.
Branches: Lateral antebrachial cutaneous nerve, muscular and articular branches.
Supply: Motor innervation to flexor muscles of the arm, sensory innervation to skin of the lateral side of the forearm, elbow joint.
Related parts of the anatomy
Origin
The musculocutaneous nerve is the main nerve of the flexor compartment of the arm. It is a branch of the lateral cord of brachial plexus, arising at the lower border of pectoralis minor muscle in the axilla. It contains nerve fibers from the anterior rami of the fifth, sixth, and seventh cervical nerves (C5—C7).
Course
Following its origin from the lateral cord of brachial plexus, the musculocutaneous nerve accompanies the third part of axillary artery in the lower part of axilla. Here, it is related anteriorly to pectoralis major, posteriorly to the subscapularis, medially to the axillary artery and lateral root of median nerve, and laterally to coracobrachialis muscle.
The musculocutaneous nerve leaves the axilla and enters the front of the arm by piercing the coracobrachialis muscle. In the arm, it runs downwards and laterally between the biceps brachii and brachialis muscles to reach the lateral side of the tendon of the biceps brachii. It continues as the lateral antebrachial cutaneous nerve in the lateral aspect of the forearm.
Branches
The musculocutaneous nerve provides muscular branches to muscles of the anterior arm and continues as the lateral antebrachial cutaneous nerve.
Supplied Structures
The muscular branches of the musculocutaneous nerve supply the coracobrachialis, biceps brachii (long and short heads), and brachialis muscles.
Cutaneous innervation is provided via the lateral antebrachial cutaneous nerve, which supplies the skin of the lateral side of the forearm, from the elbow to the wrist. Articular branches are given to the elbow joint through its branch to the brachialis muscle and to the humerus via a separate branch that enters the bone along with its nutrient artery.
List of Clinical Correlates
—Biceps myotatic reflex
—Injuries of musculocutaneous nerve (Moore, Dalley and Agur, 2013)
References
Moore, K. L., Dalley, A. F. and Agur, A. M. R. (2013) Clinically Oriented Anatomy. Clinically Oriented Anatomy 7th edn.: Wolters Kluwer Health/Lippincott Williams & Wilkins.
Learn more about this topic from other Elsevier products
Musculocutaneous Nerve
The musculocutaneous nerve, after supplying the coracobrachialis, biceps, and brachialis muscles, continues in the interval between the last two muscles as a sensory nerve to supply the skin over the anterolateral aspect of the forearm, often as far as the thenar eminence.
