In skeletal muscle, what is the primary function of a muscle spindle (a proprioceptor)?

• A. Detects changes in tendon tension and prevents excessive force by triggering the inverse stretch reflex
• B. Detects painful stimuli in muscle tissue and initiates withdrawal reflexes
• C. Detects changes in muscle length and the rate of stretch to help regulate muscle tone and the stretch reflex
• D. Measures joint capsule pressure to determine joint position during movement

Answer: (C)

Verified step by step guidance

1. Understand that muscle spindles are specialized sensory receptors located within skeletal muscles.
2. Recognize that the primary role of muscle spindles is to detect changes in muscle length and the speed at which the muscle is stretched.
3. Know that when a muscle spindle senses a stretch, it sends signals to the spinal cord to initiate the stretch reflex, which helps maintain muscle tone and posture.
4. Differentiate muscle spindles from other proprioceptors, such as Golgi tendon organs, which detect tension rather than length.
5. Conclude that the main function of muscle spindles is to monitor muscle length and stretch rate, thereby regulating muscle tone and facilitating the stretch reflex.