Which of the following conditions would most likely result from this accident?

A 16 year-old boy fell from a motorcycle, and his radial nerve was severely damaged because of a fracture of the midshaft of the
humerus. Which of the following conditions would most likely result from this accident?
(A) Loss of wrist extension leading to wrist
drop
(B) Weakness in pronating the forearm
© Sensory loss over the ventral aspect of
the base of the thumb
(D) Inability to oppose the thumb
(E) Inability to abduct the fi ngers

The answer is A. Injury to the radial nerve results in loss of wrist extension, leading to wrist drop. The median nerve innervates the pronator teres, pronator quadratus, and opponens pollicis muscles and the skin over the ventral aspect of the thumb. The ulnar nerve innervates the dorsal interosseous muscles, which act to abduct the fi ngers.