A 22-year-old man is stabbed in the anterior compartment of the right arm. He cannot flex the elbow against resistance, the biceps jerk is absent, and there is numbness along the lateral aspect of the forearm. Which nerve is injured?
- A Radial nerve
- B Musculocutaneous nerve ✓
- C Median nerve
- D Lateral cutaneous nerve of the arm
Correct answer: B. Musculocutaneous nerve
Explanation
The musculocutaneous nerve supplies coracobrachialis, biceps brachii and brachialis, so a lesion paralyses elbow flexion and abolishes the biceps jerk. It continues as the lateral cutaneous nerve of the forearm, explaining the sensory loss. The radial nerve extends the elbow rather than flexing it, which kills option A.
Reference: Moore's Clinically Oriented Anatomy, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.