40-year-old, diabetic female patient comes to see you at your clinic. She has recently taken a new job working as the personal assistant of a high-level executive. Her job requires a lot of computer work, and she frequently works overtime. She complains that she has noticed tingling in both hands that is worse on the left. When you ask her to describe the exact location, she indicates that the first three digits are more numb than the fourth and fifth digits. Irritation of which nerve is the most likely cause of her symptoms?
Axillary nerve
Median nerve
Musculocutaneous nerve
Radial nerve
Ulnar nerve
Correct answer
Median nerve
Explanation
This patient’s symptoms are a classic presentation for carpal tunnel syndrome, in which the median nerve is compressed within the carpal tunnel. This syndrome is frequently caused by overuse, as in this case, with the patient’s excess computer use.
The median nerve innervates the lateral three and a half digits on each hand, which explains the numbness in digits 1-3 in her hands. The ulnar nerve innervates the medial digit and a half of the hand, but this patient reported that her digits 4-5 were not numb.
The radial nerve innervates the back of the hand, but not the muscles within the hand. The other nerves do not innervate the hand.