This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Muscle spindle detects 
Select and explain. 
A. Tension, B. Length, C. Proprioception, D. Stretch
B: Length
Answer: B: Length 
Explanation: Muscle spindles are sensory receptors within the belly of a muscle that primarily detect changes in the length of this muscle. They convey length information to the central nervous system sensory neurons. Ref guyton and hall textbook of medical physiology 12/e pg 71