Musculocutaneous nerve
From Ganfyd
The musculocutaneous nerve is a terminal branch of the lateral cord of the brachial plexus.
| Musculocutaneous nerve | |
|---|---|
| | |
| System: | |
| Function: | |
| Origin: | Lateral cord of the brachial plexus |
| Branches: | |
| Insertion: | |
| Arterial supply: | |
| Venous drainage: | |
| Lymphatic drainage: | |
| 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. | |
Contents |
Roots
Surface anatomy
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.
Anatomical Course
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.
Sensory Supply
- Shoulder joint
- Humerus
- Elbow
- Skin of the lateral forearm via the lateral cutaneous nerve of the forearm.
Motor Supply
Terminal branch
Clinical Relevance
- Isolated lesions are rare but may accompany fractured humerus or neuralgic amyotrophy:
- Weak elbow flexion
- Extensor surface of forearm sensory impairment
Variations
- 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
