A patient with a radial nerve injury at the spiral groove of the humerus will have loss of:

• A Elbow extension (triceps paralysis), wrist extension, and finger extension
• B Wrist extension and finger/thumb extension only (triceps spared) ✓
• C All intrinsic hand muscles with sparing of extrinsic extensors
• D Thumb abduction and opposition with sparing of wrist extension

Explanation

The radial nerve supplies triceps via branches in the axilla, before it enters the spiral groove. At the spiral groove (the most common site of injury in humeral shaft fractures), the triceps branches have already been given off, so elbow extension is preserved. The injury produces wrist drop (loss of wrist extension) and loss of finger/thumb extension (extensor digitorum, extensor pollicis longus) and thumb abduction (extensor pollicis brevis, abductor pollicis longus). Sensation is lost over the dorsal first web space (superficial radial nerve).

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.