MCQ Orthopedics Answer 32

The correct answer is C.

This is a classic presentation of a patient with carpal tunnel syndrome, which typically affects females between the ages of 40 and 60 who chronically perform repetitive tasks that involve movement of the structures that pass through the carpal tunnel. One important structure that passes through the carpal tunnel is the median nerve. Patients often note a tingling, a loss of sensation, or diminished sensation in the digits. There is also often a loss of coordination and strength in the thumb, because the median nerve also sends fibers to the abductor pollicis brevis, flexor pollicis brevis, and the opponens pollicis. A final function of the median nerve distal to the carpal tunnel is control of the first and second lumbricals which function to flex digits two and three at the metacarpophalangeal joints and extend interphalangeal joints of the same digits.

Abduction of the fifth digit (choice A) is a function controlled by the ulnar nerve, which does not pass through the carpal tunnel.

Adduction of the thumb (choice B) is a function of the adductor pollicis, which is the only short thumb muscle that is not innervated by the median nerve, but rather by the deep branch of the ulnar nerve.

Sensation of the lateral half of the dorsum of the hand (choice D) is mediated by the radial nerve, which also does not pass through the carpal tunnel.

Sensation over the lateral aspect of the palm (choice E) is mediated by the median nerve, however the branch innervating the palm (palmar cutaneous branch of the median nerve) passes superficial to the carpal tunnel.

Sensation over the medial aspect of the dorsum of the hand (choice F) is mediated by the ulnar nerve.

Sensation over the medial aspect of the palm (choice G) is mediated by the ulnar nerve.

Category: Orthopedics MCQs