Professor Berger is giving a lecture about the motor systems in the body. She tells the class that Ia sensory fibers will become active in response to
A) contraction of muscle fibers.
B) input from gamma motor neurons.
C) stretching of muscle fibers.
D) input from Ib fibers.

Question

Quizplus · Accepted Answer

Ia sensory fibers become active in response to the stretching of muscle fibers. This is because Ia fibers are stretch receptors, and their activation signals the central nervous system about changes in muscle length and tension. Contraction of muscle fibers and input from gamma motor neurons do not directly activate Ia fibers, and input from Ib fibers is not relevant to Ia fiber activation.

Professor Berger Is Giving a Lecture About the Motor Systems