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Anaesthesia · Complications and emergencies: radial nerve palsy from arm positioning
Sample itemAfter surgery during which his right arm hung over the edge of the table, pressed against a metal bar, a man cannot extend the wrist or fingers and has sensory loss over the dorsum of the hand. Which nerve is injured?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
B. Radial nerve in the spiral groove
The radial nerve runs in the spiral groove of the humerus and is compressed when the arm is pressed against a hard edge. The result is wrist drop, weak finger extension and sensory loss over the dorsum of the hand. Padding and keeping the arm on a supported board prevent it.
Option by option
A. Median nerve at the carpal tunnel
Median nerve compression causes weak thumb opposition and numbness of the lateral three and a half digits on the palm side.
B. Radial nerve in the spiral groove (correct)
Correct. Wrist drop with dorsal hand sensory loss after pressure on the upper arm indicates radial nerve compression.
C. Axillary nerve at the surgical neck
Axillary nerve injury causes deltoid weakness and loss of sensation over the lateral shoulder.
D. Ulnar nerve at the medial epicondyle
Ulnar nerve injury gives a claw hand and numbness of the ring and little fingers, not wrist drop.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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