Question

A patient came to OPD with a complaint of paresis and numbness after sleeping on his arm. Why?

• A. A fibers are more susceptible to pressure than C fibers.
• B. B fibers are more susceptible to pressure than A fibers.
• C. C fibers are more susceptible to pressure than A fibers.
• D. A fibers are more susceptible to pressure than B fibers.

Hint:

Temporary compression of nerves (like sleeping on an arm) often causes numbness and weakness due to pressure on A fibers, which can be relieved by changing positions.

Answer 1

The Correct Option is A

The correct answer is A fibers are more susceptible to pressure than C fibers. The A fibers, which are responsible for motor function and touch sensation, are myelinated and larger in diameter compared to the C fibers, which are unmyelinated and smaller. As a result, A fibers are more susceptible to being compressed under pressure, causing temporary paresis (weakness) and numbness. This can occur when a person sleeps on their arm, compressing the nerves.