Saturday night palsy is associated with compression of which nerve, causing wrist drop?

Saturday night palsy is associated with compression of which nerve, causing wrist drop?

• A. Radial nerve
• B. Median nerve
• C. Ulnar nerve
• D. Phrenic nerve

Answer: (A)

Wrist drop happens when the radial nerve is compressed, because this nerve provides the major extensor muscles for the wrist and fingers. In Saturday night palsy, prolonged pressure on the arm—often from sleeping with the arm draped over a chair or pressed against a hard surface—compresses the radial nerve as it runs in the spiral groove of the humerus. When the nerve is pressed, the extensor muscles can’t contract, so you can’t straighten the wrist; the hand tends to rest in a flexed position at the wrist. Sensation over the back of the forearm and dorsum of the hand may be affected too, reflecting radial nerve involvement. The other nerves listed affect different functions: the median nerve primarily controls forearm flexors and thumb movements, the ulnar nerve supplies many intrinsic hand muscles, and the phrenic nerve controls the diaphragm. So the radial nerve is the one whose disruption leads to wrist drop in this scenario.

Wrist drop happens when the radial nerve is compressed, because this nerve provides the major extensor muscles for the wrist and fingers. In Saturday night palsy, prolonged pressure on the arm—often from sleeping with the arm draped over a chair or pressed against a hard surface—compresses the radial nerve as it runs in the spiral groove of the humerus. When the nerve is pressed, the extensor muscles can’t contract, so you can’t straighten the wrist; the hand tends to rest in a flexed position at the wrist. Sensation over the back of the forearm and dorsum of the hand may be affected too, reflecting radial nerve involvement. The other nerves listed affect different functions: the median nerve primarily controls forearm flexors and thumb movements, the ulnar nerve supplies many intrinsic hand muscles, and the phrenic nerve controls the diaphragm. So the radial nerve is the one whose disruption leads to wrist drop in this scenario.