Kinesthesis is the ability to perceive your position and movement of the body and/or limbs in space. Kinesthesis relies on the use of various receptors in the joints, muscles and tendons. For example, the muscle spindle that lies in parallel with the muscle fibers is activated when the muscle is stretched during an eccentric contraction (This is known as the stretch reflex).
The Golgi tendon organs are other receptors located at the junction of the tendon and the muscle. They respond to the amount of stretch taking place in the tendon and the muscle. It is important to understand that when a muscle stretches, the tendon also undergoes stretching. It is very elastic tissue and can withstand great tension.
When activated, the Golgi tendon organs trigger the antagonistic muscle groups to stop the movement and to inhibit the agonist muscle contraction. This is done to avoid possible injury to the muscle-tendon complex. Because of their actions, it is much easier to fully stretch a muscle when the Golgi tendon organs are shut down. There are also receptors located in the joint capsules and in the ligaments that relay information to the brain. This includes a change in position, speed of movement, or the acceleration of the limbs that occur at the joints.
These receptors are very sensitive and fire when there is a small change (up to two degrees) in joint position. There are also many pressure receptors that are very active in posture. When there is any deviation in position, they are fired so that a correction can be made to bring you back into the normal position.
