Radial Nerve (C5–T1) Injury
The radial nerve follows a long course down the arm, making it susceptible to injury at various anatomical locations.
| Site of Injury | Key Presentation |
|---|---|
| Axilla (e.g., “crutch palsy”) | Loss of elbow extension (triceps), wrist drop, sensory loss (arm/forearm/hand). |
| Mid-shaft Humerus (spiral groove) | Wrist drop, loss of finger extension; triceps spared (innervated proximally). |
| Posterior Interosseous Nerve (PIN) | Finger drop (no wrist drop because wrist extensors often spared); no sensory loss. |
High-Yield Clinical Notes:
- Sensory Distribution: Primarily over the posterior arm, posterior forearm, and the “anatomical snuffbox” dorsum of the hand.
- Wrist Drop: Classic sign due to paralysis of all extensor muscles of the forearm.
- Humerus Fractures: Mid-shaft fractures are classically associated with damage to the radial nerve in the spiral groove.