The Human Brain : From Neurone to Nervous System

SENSORY RECEPTORS in Muscles Tendons and Joints

  1. Sensory receptors in muscles tendons and joints are nerve endings that monitor events in the locomotor system, such as muscle length, muscle tension and joint position.

  2. Sensory receptors in muscles, tendons and joints are responsible for the sense of position of the limbs - proprioception. They are also responsible for different varieties of reflex activity.

  3. Muscle spindles monitor muscle length and and vibration, and are receptors whose senitivity can be changed by a special efferent innervation of their intrafusal fibres - the gamma efferent system.

  4. Muscle spindles are the receptor involved in the stretch reflex (knee jerk).

  5. Golgi Tendon Organs monitor the tension in the muscles.

  6. Joint receptors also monitor the angle of joints.

  7. All three receptors are involved in proprioception- the sense of position of the limbs.

  8. Key Words : Muscle spindle (muscle length, vibration), Golgi Tendon Organs (muscle tension), joint receptors (joint angle); Muscle spindle sensitivity can be adjusted by the gamma efferent system.

Additional Details of the Muscle Spindle and the Gamma Efferent System

The 'in series' situation of Golgi Tendon Organs.

Golgi Tendon Organs are situated at the muscle tendon junction,'in series' with the extrafusal fibres, which has two consequences:

  • when the muscle is stretched, the tendon organ is stretched, and the Ib that fibres that innervate them increase their discharge in proportion to the increase in tension. Ib fibres have a high threshold to tension generated by stretching the muscle.
  • when the extrafusal fibres contract the force of contraction is exerted on the muscle-tendon junction, and the tendon organ increases its rate of discharge according to the tension generated.