Upper limb
Radial nerve
Nervus radialis
- Origin
- Largest terminal branch of the posterior cord of the brachial plexus (C5–T1)
- Insertion
- Passes through the triangular interval, spirals in the radial groove of the humerus with profunda brachii artery, pierces the lateral intermuscular septum, enters the antecubital fossa, and bifurcates into superficial (sensory) and deep/posterior interosseous (motor) branches
- Function
- Motor to all extensor muscles of the arm (triceps, anconeus) and forearm (brachioradialis, wrist extensors, digital extensors, supinator, abductor pollicis longus); sensory to the posterior arm, posterior forearm, dorsal radial hand, and proximal dorsal digits I–III
- Innervation
- Major mixed nerve providing motor supply to all posterior limb extensors
- Movement & chain
- Drives elbow extension, wrist extension (crucial for tenodesis grip strength), MCP extension, and thumb extension/abduction
- Palpation
- Palpable along the lateral supracondylar ridge of the humerus and superficially over the anatomical snuffbox
- Clinical
- Wrist drop (inability to extend wrist and digits, classical sign of high radial nerve injury), 'Saturday night palsy' (crush neurapraxia against humerus), midshaft humerus fractures, posterior interosseous nerve (PIN) syndrome / arcade of Frohse entrapment, Wartenberg's syndrome (cheiralgia paresthetica)
- Segmental innervation
- C5, C6, C7, C8, T1 spinal cord levels
- In clinical practice
- Dynamic wrist extension splints to maintain functional hand use, neurorehabilitation, nerve grafting, and tendon transfers (e.g., PT to ECRB, FCU to EDC) for irreparable lesions
- Region in the model
- Upper limb