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Upper limb nerve injuries
Where each nerve is injured, what is lost, and the sign that gives it away.
| Nerve (roots) | Typical injury | Motor loss | Sensory loss | Classic sign |
|---|---|---|---|---|
| Axillary (C5–C6) | Fracture of the surgical neck of the humerus; anterior shoulder dislocation | Deltoid, teres minor — weak abduction | "Regimental badge" patch over the lateral shoulder | Flattened deltoid |
| Musculocutaneous (C5–C7) | Uncommon; penetrating trauma | Biceps, brachialis, coracobrachialis — weak elbow flexion and supination | Lateral forearm | Lost biceps reflex |
| Radial (C5–T1) | Midshaft humerus fracture (spiral groove); "Saturday night palsy"; crutch pressure in the axilla | Wrist and finger extensors (triceps too if injured in the axilla) | Dorsum of the hand over the first web space | Wrist drop |
| Median — at the elbow | Supracondylar humerus fracture | Pronators, lateral forearm flexors, thenar muscles | Lateral 3½ digits and lateral palm | Hand of benediction when making a fist |
| Median — at the wrist | Carpal tunnel syndrome; wrist laceration | Thenar muscles and lateral two lumbricals ("LOAF") | Lateral 3½ digits (palm spared — palmar cutaneous branch) | Thenar atrophy; Tinel and Phalen signs |
| Ulnar — at the elbow | Medial epicondyle fracture; cubital tunnel (leaning on the elbow) | Flexor carpi ulnaris, medial flexor digitorum profundus, most intrinsic hand muscles | Medial 1½ digits | Claw of the 4th and 5th digits; Froment sign |
| Ulnar — at the wrist | Guyon canal compression (cyclists); hook of hamate fracture | Intrinsic hand muscles | Medial 1½ digits (palmar) | More obvious clawing than an elbow lesion ("ulnar paradox") |
| Long thoracic (C5–C7) | Axillary node dissection or mastectomy; chest tube; heavy backpack | Serratus anterior | None | Medial scapular winging |
| Upper trunk of the brachial plexus (C5–C6) | Erb palsy — shoulder dystocia, fall forcing the head and shoulder apart | Shoulder abductors and external rotators, elbow flexors, supinators | Lateral arm and forearm | "Waiter's tip" posture |
| Lower trunk of the brachial plexus (C8–T1) | Klumpke palsy — arm pulled upward (breech delivery, grabbing a branch); Pancoast tumor; cervical rib | Intrinsic hand muscles | Medial forearm and hand | Total claw hand ± Horner syndrome |
The ulnar paradox: a proximal ulnar lesion also weakens the medial FDP, so the fingers flex less and the claw looks milder than with a lesion at the wrist.