Ia sensory fibers synapse directly with alpha motor neurons
1b sensory fibers synapse with inhibitory interneurons.
Excitatory interneurons in the withdrawal reflex.
gamma motor neurons synapse w/ supraspinal systems
withdrawal reflex is activated by stimuli from free nerve endings.
Muscle spindles provide the afferent signals for the stretch reflex
golgi tendon organs are the source of stimuli for the inverse myotatic reflex
golgi tendon afferents synapse
with 1b inhibitory interneurons
Signals from Golgi tendon organs lead to inhibition
muscle spindle activity leads to excitation of the muscles
golgi and spindle function in the course of normal movement
golgi afferents conduct more slowly than spindle afferents
golgi input to interneurons and not motor neurons, similar to the muscle spindles.
golgi send higher signals to cerebellum
Descending supraspinal axons synapse with either gamma
passive stretching muscle spindle, 1a sensory, then alpha motor. gamma motor and 2 sensory have no role in stretch reflex
dynamic nuclear bag responsible for dynamic response
inc. activity of gamma motor inc sensitivity of stretch reflex
Dynamic gamma motor neurons innervate dynamic nuclear bag fibers
From reticular activating system --> intralaminar nuclei of thalamus --> cortex (activation)
The contractile elements of intrafusal fibers are found at the periphery
Both types of sensory fibers in a muscle spindle are mechanoreceptors
Motor neurons in Ant horn exit SC by ant root
sensory enter SC by post root to sit in post horn
T1-L2 preganglionic sympathatic fibers
cutting dorsal root removes afferent 1a from stretch reflex arch
muscle spindle & stretch reflex
autogenic inhibition & golgi
reciprocal inhibition & stretch reflex
Crossed extensor reflex: pain signals that
elicit movements performed by antagonistic muscle groups