Nerve
Median nerve
Major nerve for forearm flexor muscles and thumb control
High-yield
The recurrent branch supplies the principal thenar muscles; digital branches supply the first two lumbricals. The palmar cutaneous branch leaves before the carpal tunnel, explaining why thenar skin sensation is usually spared in carpal tunnel syndrome.
Overview
Contributions from the lateral and medial cords unite as the median nerve. Its branches reach most anterior forearm muscles, several small hand muscles and much of the skin on the thumb side of the palm and fingers.
Learning this group? Read How to learn the brachial plexus.
Reference facts
- Root value
- Lateral and medial cord fibers, chiefly C6-T1 with a variable C5 contribution
- Course
- Accompanies and usually crosses in front of the brachial artery; enters the forearm between the pronator-teres heads; continues between FDS and FDP and through the carpal tunnel
- Motor
- Most anterior forearm muscles except FCU and the ulnar FDP portion; abductor pollicis brevis, opponens pollicis, usually superficial FPB, and the first two lumbricals. Median-ulnar connections can modify this pattern
- Sensory
- Palmar thumb, index, middle and radial half of ring finger, with their distal dorsal tips/nail regions; lateral palm via the palmar cutaneous branch
Mnemonic
Separate the hand branches by destination: recurrent turns back toward the thenar muscles; digital branches continue toward the fingers and the first two lumbricals.
Clinical correlation
Compression in the carpal tunnel can cause tingling in the thumb, index, middle and radial ring finger, with thenar weakness in more advanced disease. A more proximal lesion may also weaken forearm muscles; hand posture alone is not enough to localize it.
Frequently asked questions
What are the roots of the median nerve?
Lateral and medial cord fibers, chiefly C6-T1 with a variable C5 contribution.
What muscles does the median nerve supply?
Most anterior forearm muscles except FCU and the ulnar FDP portion; abductor pollicis brevis, opponens pollicis, usually superficial FPB, and the first two lumbricals. Median-ulnar connections can modify this pattern.
What is the sensory distribution of the median nerve?
Palmar thumb, index, middle and radial half of ring finger, with their distal dorsal tips/nail regions; lateral palm via the palmar cutaneous branch.
What is the course of the median nerve?
Accompanies and usually crosses in front of the brachial artery; enters the forearm between the pronator-teres heads; continues between FDS and FDP and through the carpal tunnel.