This preview shows page 1. Sign up to view the full content.
Unformatted text preview: - Two groups of afferents coming from muscle spindle: - Both slowly-adapting - Ia (big ones): strong dynamic sensitivity - Respond to rate of change of stimulus - i.e. at beginning of stretch - Sensitive to velocity of stretch - II: more statically sensitive Somatosensory Receptors - Weak response to rate of change - Main response to size of stimulus (sustained part)
Golgi tendon organ Group Ib Proprioceptor: Golgi tendon organ Located at junction of muscle fibers with - Completely diff focus: activated by active contractile force tendon generated by muscle terminal branches of group Ib sensory axon entwined with collagen fibers of tendon - Contraction removes tension: gamma motoneurons distorted by force of active contraction slowly-adapting resensitive muscle spindles - Opposite of Golgi tendon organ - Located at jxn of muscle fibers w/ tendon (which joins to bone) - Terminal branches of group Ib sensory axon interspersed and entwined among collagen fibers of tendon - Muscle contraction: pull on collagen fibers & squeeze them together - Squeeze on axon terminals = receptor potential -> a.p. - Slowly-adapting: discharge a.p. throughout duration of stimulus - Whereas Ia afferents: muscle shortening = stop firing - Gamma motoneurons can re-sensitive spindle? No: w...
View Full Document
- Fall '11