The Musculocutaneous Nerve - Podcast Version 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The musculocutaneous nerve is a major peripheral nerve of the upper limb. In this article, we shall look at the anatomy of the musculocutaneous nerve – its anatomical course, motor and sensory functions, and its clinical correlations. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Overview Nerve roots – C5-C7. Motor functions – muscles in the anterior compartment of the arm (coracobrachialis, biceps brachii and the brachialis). Sensory functions – gives rise to the lateral cutaneous nerve of forearm, which innervates the lateral aspect of the forearm. Pro Feature - Dissection Atlas Prosection of the brachial plexus, demonstrating the medial and lateral cords. The posterior cord is a deeper structure and can not be visualised. Prosection of the brachial plexus, demonstrating the medial and lateral cords. The posterior cord is a deeper structure and can not be visualised. You've Discovered a Pro Feature Access our Dissection Image Library Enhance your understanding with high-resolution dissection images showcasing real-life anatomy. Learn More Anatomical Course The musculocutaneous nerve is the terminal branch of the lateral cord of the brachial plexus (C5, C6 and C7) and emerges at the inferior border of pectoralis minor muscle. It leaves the axilla and pierces the coracobrachialis muscle near its point of insertion on the humerus. It gives a branch to this muscle. The musculocutaneous nerve then passes down the flexor compartment of the upper arm, superficial to brachialis but deep to the biceps brachii muscle. It innervates both these muscles and gives articular branches to the humerus and the elbow. The nerve then pierces the deep fascia lateral to biceps brachii to emerge lateral to the biceps tendon and brachioradialis. It continues into the forearm as the lateral cutaneous nerve and provides sensory innervation to the lateral aspect of the forearm. Note: The musculocutaneous nerve is well recognised to have a varied anatomical course. It can interact with the median nerve, adhering to the nerve and exchanging fibres. Alternatively, it may pass under the coracobrachialis instead of through it, and/or through the biceps brachii. By TeachMeSeries Ltd (2026) Fig 1The anatomical course of the musculocutaneous nerve. Motor Functions The musculocutaneous nerve innervates the muscles in the anterior compartment of the arm: Biceps brachii Brachialis Coracobrachialis These muscles flex the upper arm at the shoulder and the elbow. In addition, the biceps brachii also supinates the forearm. A useful mnemonic to help you remember these muscles is BBC. Sensory Functions The musculocutaneous nerve gives rise to the lateral cutaneous nerve of forearm. This nerve initially enters the deep forearm, but then pierces the deep fascia to become subcutaneous. In this region, it can be found close to the cephalic vein. The lateral cutaneous nerve of forearm innervates the skin of the anterolateral aspect of the forearm. By TeachMeSeries Ltd (2026) Fig 2Cutaneous distribution of the musculocutaneous nerve. Clinical Relevance Injury to the Musculocutaneous Nerve The musculocutaneous nerve is well protected within the axilla and injury is relatively uncommon. Characteristic mechanisms of injury include penetrating trauma to the axilla (e.g. stabbing), and iatrogenic injury resulting from heavy retraction during the deltopectoral approach to the shoulder. Motor functions – coracobrachialis, biceps brachii and brachialis muscles are affected: Flexion at the shoulder and elbow are weakened but can still be performed by the pectoralis major and brachioradialis respectively. Supination of the forearm is weak, but can still be performed by the brachioradialis. Sensory functions – loss of sensation over the lateral side of the forearm. Do you think you’re ready? Take the quiz below Pro Feature - Quiz The Musculocutaneous Nerve Question 1 of 3 Submitting... Skip Next Rate question: You scored 0% Skipped: 0/3 1800 More Questions Available Upgrade to TeachMeAnatomy Pro Challenge yourself with over 1800 multiple-choice questions to reinforce learning Learn More Frequent questions What is the musculocutaneous nerve and its primary functions? The musculocutaneous nerve is a significant peripheral nerve of the upper limb, primarily responsible for motor innervation to the anterior compartment muscles of the arm, including the biceps brachii, brachialis, and coracobrachialis. It also provides sensory innervation to the lateral aspect of the forearm through the lateral cutaneous nerve of the forearm. What muscles are innervated by the musculocutaneous nerve? The musculocutaneous nerve innervates three key muscles in the anterior compartment of the arm: the biceps brachii, brachialis, and coracobrachialis. These muscles are involved in flexing the shoulder and elbow, with the biceps brachii also aiding in forearm supination. How does the musculocutaneous nerve course through the arm? The musculocutaneous nerve originates from the lateral cord of the brachial plexus and emerges at the inferior border of the pectoralis minor. It pierces the coracobrachialis muscle, travels down the flexor compartment of the arm, and provides branches to the biceps brachii and brachialis before becoming the lateral cutaneous nerve of the forearm. What are the clinical implications of an injury to the musculocutaneous nerve? Injury to the musculocutaneous nerve is uncommon but can occur due to penetrating trauma or surgical complications. Such injuries can lead to weakened flexion at the shoulder and elbow, as well as diminished supination of the forearm, while sensory loss may occur over the lateral forearm. What is the sensory function of the musculocutaneous nerve? The musculocutaneous nerve provides sensory innervation through the lateral cutaneous nerve of the forearm, which supplies sensation to the skin on the anterolateral aspect of the forearm. This sensory branch emerges subcutaneously after piercing the deep fascia in the forearm region. Rate This Article