What does the Golgi Tendon Organ sense?

The Golgi Tendon Organ (GTO) is a proprioceptive sensory receptor located at the musculotendinous junction. Its primary function is to sense changes in muscle tension that occur when muscles contract. When tension increases, especially at high levels, the GTO functions to monitor that tension and send signals to the central nervous system to prevent excessive force that could potentially lead to injury. This protective mechanism allows the body to adjust muscle contraction to avoid damage.

The focus of the Golgi Tendon Organ on muscle tension distinguishes it from other proprioceptors. For example, muscle length and contraction speed are mainly monitored by muscle spindle fibers, which respond to changes in the length of muscle fibers and the rate of that change. Similarly, joint angles and positions are primarily sensed by receptors located in the joint itself, such as joint receptors and also indirectly via muscle spindle activity. Finally, the stretch of muscle fibers is a key function of the muscle spindle and is not the primary role of the Golgi Tendon Organ.