5.2 Sensory & Motor Pathways Flashcards
What receptors are on fingers and palm of hand, plantar surface of foot and toes?
Meissner’s corpuscles
What receptors are sensitive to touch and vibration?
Meissner’s corpuscles
What receptors are on lips, distal parts of extremities?
Merkel’s receptors
What receptors are sensitive to pressure stimuli, and low frequency vibration?
Merkel’s receptors
What receptors are found on hands and feet, walls of mesenteries, vessel walls, periosteum, and joint capsules?
Pacinian corpuscles
What receptors are sensitive to rapid indentation of skin (high frequency vibration)?
Pacinian corpuscles
What receptors are widely distributed in dermis layer of skin?
Ruffini’s corpuscles
What receptors are sensitive to stretch?
Ruffini’s corpuscles
Where are proprioceptors located?
in joint capsules
Where are cell bodies that mediate touch and conscious proprioception located; first order neurons of DCML?
dorsal root ganglia
What fibers are located in the fasciculus gracilis?
central axons of sensory neurons (from receptors that mediate tactile sensation and proprioceptors of joints) at and below T6
What fibers are located in the fasciculus cuneatus?
central axons of sensory neurons (from receptors that mediate tactile sensation and proprioceptors of joints) above T6
Where do the fibers of the fasciculus gracilis and cuneatus synapse?
Upon 2nd order neurons in the dorsal column nuclei of the medulla (nucleus gracilis and nucleus cuneatus)
Do the fibers in the fasciculus gracilis and cuneatus tracts stay on the same side or do they cross to the contralateral side?
ascend ipsilaterally in the spinal cord
Where do the fibers of the nucleus gracilis and cuneatus decussate?
at the level of the medulla
What do the fibers of the nucleus gracilis and cuneatus form after they decussate?
medial lemniscus
Where do fibers from the medial lemniscus travel and project to?
Ascend through medulla, pons and midbrain, then project to 3rd order neurons in the VPL nucleus of thalamus.
Where do the 3rd order neurons of the VPL project to?
primary somatosensory cortex = postcentral gyrus
Where are lower motor neurons for the head from?
motor neurons of cranial nerves
Where are lower motor neurons for the body from?
in the ventral horn of the spinal cord
Where do upper motor neurons arise?
cerebral cortex
Upper motor neurons of the Corticospinal tract from the cerebral cortex project to lower motor neurons of what?
spinal cord (voluntary control for movement of body)
Upper motor neurons of the Corticobulbar tract from the cerebral cortex project to lower motor neurons of?
brainstem (CN i.e. facial motor nucleus, trigeminal m. n.) and (voluntary control fro movement)
What participates in control of movement by receiving inputs from cerebral cortex and feeding back signals to different regions of the frontal cortex involved in initiation of movement?
Basal ganglia
How does the basal ganglia play a role in motor function?
modulates activity of upper motor neurons
What receives inputs from and gives outputs to most parts of CNS that contribute to motor functions?
cerebellum
How does the cerebellum play a role in motor function?
Serves as the principal integrator of motor function
What regions influence the pre central gyrus?
(1) motor activity regulation from several regions of CNS including cerebellum and basal ganglia via VL (2) somatosensory afferents from postcentral gyrus via VPL
Where does the primary motor cortex (pre central gyrus) project to and via which pathways? (2)
(1) ventral horn of spinal cord at all levels via corticospinal tract
(2) lower motor neurons composing cranial motor nuclei of brainstem via corticobulbar tract
What is the result of activation of the descending fibers of the primary motor cortex?
muscle contractions of individual muscles and controls the tone of these muscles
What area do inputs received from basal ganglia primarily go to?
Supplemental motor area via VL
What area do inputs received from the cerebellum primarily go to?
premotor cortex via VL
Where do the Premotor and Supplemental Motor Cortices also receive inputs from?
Posterior parietal cortex, including somatosensory inputs from post central gyrus and from vestibular and visual areas
Where do the premotor and supplemental motor cortices project to? and via which fiber pathway?
corticospinal tract to ventral horn
What is the result of activating fibers of the premotor and supplemental motor cortices?
coordinate voluntary movements, sequencing of response patterns that are essential for producing movements
What results from the inability to initiate specific, purposeful movements; moving planning deficits?
Apraxia
What are the 3 different regions of origin of the Corticospinal tract?
pre central gyrus (primary motor cortex), premotor cortex, and supplemental motor area
Axons of the corticospinal tract travel through the white matter of the cortex, followed by what 2 structures to reach the lower brainstem?
internal capsule (posterior limb) and then through the crus cerebri (midbrain)
Where does the Corticobulbar tract arise from?
lateral aspect of primary motor cortex (pre central gyrus)
What are the 2 exceptions to the bilateral innervation of the Corticobulbar pathway?
contralateral innervation of the ventral cell groups of motor nucleus of CN VII and CN XII
Axons of the corticobulbar tract travel through the white matter of the cortex, followed by what 2 structures before exiting at their appropriate levels of the brainstem?
internal capsule (gene) and crus cerebri (midbrain)
