muscle receptor physiology

muscle spindle / DTR

responds to muscle spindle stretch

reflex contraction due to stretch of gamma motor neuron activation

conscious proprioception

awareness of the sense of force created by muscle contraction

where are alpha motor neurons founc

muscle fiber

where is muscle fibers found

intrafusal

muscles that are responsible for fine, skilled movements have higher density of what

muscle spindles

nuclear bag fibers

type of intrafusal fiber

nuclei is scattered

bigger than nuclear chain

nuclear chain fibers

type of intramural fiber

nuclei are in a line

smaller / thinner than bag fibers

primary sensory ending (Ia fibers)

detect velocity of stretch of muscle and absolute length of muscle

wrapped around nuclear chain and bag

secondary sensory ending (II fibers)

only detect absolute length of the muscle

smaller than Ia

efferent motor intervention

muscle spindle is the only sensory receptor to have this

motor component

gamma motor neurons

attached to the intrafusal fibers at the contractile ends of the fiber

is always turned on

enables intrafusal fibers to contract

activated by CNS

alpha-gamma coactivation

activated by CNS

keeps the spindle shortened to correspond with he length of extrafusal fibers and allow for immediate response by spindle

alpha motor neuron is damaged =

muscle contraction will not work and reflex will be absent

some alpha motor neurons damaged =

reflex will be hypo reflexive

GTO

found in musculotendinosus junction

sensory component

reflex control of muscle tension - opposite of muscle spindle

Ib fibers

what is the stimulus for GTO

muscle contraction or extreme passive stretch

somatosensory cortex (postcentral gyrus)

somatomotor cortex (pre central gyrus)

meninges layers from superficial to deep

dura

arachnoid

pia

where is CSF located

subarachnoid space

what is it and what does it include

diencephalon

includes: thalamus and hypothalamus

what level does the spinal cord end

L1 / L2