The central nervous system (CNS) receives information from the individual skeletal muscle. It also sends commands for action to the muscle.
The usual general sensations of pain, temperature, pressure, etc., are included in the input from the skeletal muscle.
Associated with the individual skeletal muscle are two sense organs which analyze the degree of tension or stretch of the muscle as a whole.
The stretch reflex. The muscle spindle is located within the substance of the fleshy belly of the muscle. The muscle spindle is very sensitive to the length of the muscle. It continuously sends information about the specific length of the muscle.
The Golgi tendon organ reflex. Another stretch receptor is the Golgi tendon organ. As its name implies, it is located in the tendon of the muscle. When it informs the CNS that the stretch is excessive, the CNS commands the muscle to relax.