|Origin:||Lateral cord of the brachial plexus|
|Innervation:||Coracobrachialis, shoulder, biceps brachii, brachialis, elbow|
|Vertebral levels:||C5 nerve root, C6 nerve root, C7 nerve root|
|Search for Musculocutaneous nerve in Gray's.|
The course of the nerve is denoted by a line from the lateral side of the third part of the axillary arteryto the lateral side of the biceps tendon.
The nerve arises obliquely from the lateral cord posterior to the the lower border of pectoralis minor. It pierces coracobrachialis, supplying this muscle, to descend between biceps brachii and brachialis towards the lateral side of the arm. Below the elbow it pierces the deep fascia to become its terminal sensory branch, the lateral cutaneous nerve of the forearm.
- Shoulder joint
- Skin of the lateral forearm via the lateral cutaneous nerve of the forearm.
- Isolated lesions are rare but may accompany fractured humerus or neuralgic amyotrophy:
- Weak elbow flexion
- Extensor surface of forearm sensory impairment
- Coracobrachialis is supplied by the C7 fibres; these may supply the muscle directly as a separate nerve branching from the lateral cord.
- May run posterior to coracobrachialis
- May run with or attached to the median nerve for some distance
- Some fibres of the median nerve may run in the musculocutaneous nerve before communicating across
- Some fibres of the musculocutaneous nerve may run in the median nerve before communicating across
- May supply pronator teres