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C h e c k o u t A B M P 's l a t e s t n e w s a n d b l o g p o s t s . Av a i l a b l e a t w w w. a b m p . c o m . 45 FUNCTIONAL ANATOMY education Golgi Tendon Organs By Christy Cael In the last edition of Functional Anatomy (March/ April 2016), we expanded our focus beyond muscles and muscle groups to include other structures affected by bodywork. We began with an examination of the muscle spindle and continue here with the Golgi tendon organs. PROPRIOCEPTION Like the muscle spindles we explored last time, Golgi tendon organs are proprioceptors and contribute to an overall awareness of body position. Various sensory structures—in the joints, muscles, and tendons, including Golgi tendon organs—communicate positional information to the central nervous system in an effort to maintain balanced posture, create smooth and efficient movement, and prevent injury. GOLGI TENDON ORGAN ANATOMY Golgi tendon organs are sensory structures woven into tissues at the musculotendinous junction near the origins and insertions of skeletal muscles. This location is slightly different than that of muscle spindles, which are located within the muscle belly. Each Golgi tendon organ is made of collagen intrafusal fibers that run parallel to the tendon at one end and extend into the muscle belly at the other. A dense capsule of extrafusal fibers, which are tightly packed strands of collagen, encloses the Golgi tendon organ. A single afferent nerve fiber within the capsule branches out and spirals its terminal ends around individual convoluted intrafusal fibers and detects changes in tissue. Where the muscle spindles monitor the rate of length change when muscles stretch, the Golgi tendon organs monitor changes in muscle tension. Muscle tension is created when muscles lengthen and stretch, and also when they are activated to create isometric or isotonic muscle contractions. As muscle tension increases, the sensory terminals Sensory fiber Muscle Tendon fascicles (collagen fibers) connected to bone Golgi tendon organ The Golgi tendon organ monitors changes in muscle tension. Image courtesy Mikkel Juul Jensen Science Photo Library.