Proprioceptors

Proprioceptors

give nervous system information about body position and movement

types of proprioceptors

muscle spindles, golgi tendon organs, and joint receptors

muscle spindles

part of a reflexive feedback system that is responsible for maintaining muscle length in response to changes in load or pull on the muscle

extrafusal fibers

muscle fibers within skeletal muscles that are directly responsible for muscle contraction

intrafusal fibers

6-10 striated muscle fibers within muscle spondles that do not contribute to the force of muscle contraction, in parallel with extrafusal fibers

group Ia afferents

wrao around intrafusal fibers in central part of muscle spindle

group II afferents

located near ends of muscle spindles

dynamic phase

stretching or shortening of muscle

static phase

no change in muscle length

Ia afferents are rapidly adapting

most responsive in response to the dynamic phases of muscle stretch, sensitive to velocity and stretch of muscle, firing rate is proportional to amount of stretch during static phase

II afferents are slowly-adapting

fire action potentials ar rate proportional to amount of stretch furing static phase, but firing doesn’t change dramatically during dynamic phases. Primary signal amount of stretch furing static phase

Golgi tendon organ

regulates muscle tension in response to changes in load or pull on the muscle, helps prevent damage to a muscle that would otherwise occur if it was under too much load

group Ib afferent sensory fibers

innervate GTOs