system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Muscles have which efferent nerve fibers for regulating tone?
assistant
The correct answer is  Ans. is 'b' i.e., Gamma neuron(Ref: Ganong 23'd/e p.158-162; Guyton 12n/e p. 657)Muscle tone is maintained by stretch reflex through muscle spindles (intrafusal fibers).