In addition to muscle spindles that sense change in muscle length, Golgi tendon organs (GTO), located in the tendons, also monitor muscle tension (see Fig-ure 4.13). GTO are sensory nerve endings that are wrapped around the collagen fibers of tendons. About 10 to 15 muscle fibers are attached to each GTO. When the muscle contracts, the stretch of the collagen
fibers stimulates the GTO, which convey impulses to interneurons located in the central nervous system. These neurons inhibit the motor neuron innervating the muscle in question and produce reflex muscle re-laxation. In this way, the Golgi tendon organs protect the muscle from contracting with excessive force and speed and becoming injured.
In addition to the muscle spindles and Golgi tendon or-gans, receptors present in the capsules of joints and lig-aments respond to pressure and acceleration and de-celeration of joint movement. They convey information regarding joint movement and position to the brain.