Question

After surgery, a patient complains of numbness in the lateral hand and fourth and fifth finger, as well as being unable to firmly close their little finger against their thumb. Why does the motor dysfunction suggest a more significant ulnar nerve injury and a slower recovery time than a neuropathy with only sensory loss?

A) The motor fibers are damaged more easily than sensory fibers.
B) Sensory fibers heal more quickly than motor fibers.
C) A more significant ischemic injury has occurred if the motor fibers deep in the ulnar nerve are affected.
D) The motor fibers are more superficial on the ulnar nerve.

Answer 1

The inability to firmly close the little finger against the thumb after surgery, accompanied by numbness, hints at a significant ulnar nerve injury. This indicates a more serious injury affecting the deeper motor fibers within the nerve, which heal more slowly than sensory fibers, leading to longer recovery times.

Step-by-step explanation:

The motor dysfunction in the patient who is unable to firmly close their little finger against their thumb, along with numbness in the lateral hand and fourth and fifth finger, suggests a significant ulnar nerve injury. This situation indicates a more severe injury, with the likelihood of affecting both the sensory and motor fibers of the ulnar nerve. The correct answer to why this suggests a slower recovery than a neuropathy with only sensory loss is C) A more significant ischemic injury has occurred if the motor fibers deep in the ulnar nerve are affected. This is because the motor fibers are located deeper within the nerve and are less susceptible to damage compared to sensory fibers. Hence, when motor dysfunction is evident, it implies a more severe injury likely took place, which in turn requires a longer recovery period. It is typically understood that motor fibers heal more slowly than sensory fibers, contributing to the prolonged recovery.