Following an anterior dislocation of the shoulder that was reduced, a patient has profound weakness of elbow flexion with preserved brachioradialis reflex, and numbness confined to the lateral aspect of the forearm. Which nerve is injured?

• A Musculocutaneous nerve ✓
• B Radial nerve
• C Median nerve
• D Axillary nerve

Explanation

The musculocutaneous nerve pierces coracobrachialis and supplies biceps and brachialis before continuing as the lateral cutaneous nerve of the forearm. Injury produces weak elbow flexion with loss of sensation only over the lateral forearm. The biceps reflex is typically diminished, distinguishing it from a pure C5 radiculopathy. Radial nerve injury causes wrist drop and dorsal hand sensory loss, and axillary nerve injury causes deltoid weakness with regimental badge anaesthesia.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.