Discriminative Touch Flashcards
What carries the mechanoreceptor information from the body?
Dorsal column-medial lemniscal (DC-ML) system
Central processes of ____ enter the spinal cord.
1 degree afferents
The dorsal columns consists of the ____ and _____, which are composed of axons of mechanoreceptor afferents. They are positioned in the dorsal columns in a ______ order.
cuneate and gracile fasciles; somatotopic
The ______ is analogous to the dorsal root (spinal) ganglion in that it contains the cell bodies of sensory neurons
trigeminal ganglion
Mechanoreceptive afferent fibers largely synapse in the _____, often referred to as the ______ of the trigeminal nucleus
pontine region; main sensory subnucleus
Exceptions are ______, for which the cell bodies are within the mesencephalic trigeminal nucleus, and not the trigeminal ganglion
proprioceptive signals from muscle afferents and PDL afferents
The ______ is bringing in afferent signals originating from the body while the _______ is bringing in afferent signals originating from the head.
medial lemniscus; trigeminal lemniscus
_____ is the organized map of the body as represented in a particular brain region
somatotopy
Neurons in the ___ and ___ project to the primary somatosensory cortex, which lies along the post-central gyrus of the cerebral cortex
VPL and VPM thalamus
Body regions are represented along different regions of the post-central gyrus, with the trigeminal signals located most _____, the lower body (sacral dermatomes) represented most ______
laterally; medially
____ RFs and _____ mechanoreceptor density allow for greater tactile acuity discrimination
Smaller; higher
Injury to peripheral nerves cause changes in the body representation in the cerebral cortex, which change over time; just what changes occur depends upon the ______
degree of nerve regeneration
body representation increases as a result of _______
repetitive and prolonged input
MECHANORECEPTORS INFORMATION FROM BODY: Central process of primary afferent enter the spinal cord and project to the cerebral cortex via:
dorsal column
MECHANORECEPTORS INFORMATION FROM BODY: Secondary neurons projections:
internal arcuate fibers (crossing the midline!), then contralateral medial lemniscus
MECHANORECEPTORS INFORMATION FROM BODY: Synapse with tertiary neurons:
ventral posterior lateral (VPL) of the thalamus
MECHANORECEPTORS INFORMATION FROM BODY: Tertiary neuron projections:
posterior limb of internal capsule, then post central gyrus (S1 cortex)
DISCRIMINATIVE TOUCH: Central processes of primary afferents form root of CN V make connections for: Projections to cerebral cortex:
chief sensory nucleus of V - primary afferents synapse with 2o neurons
contralateral trigeminal lemniscus
ventral posterior medial (VPM) nucleus of thalamus, synapse with 3o neurons
posterior limb of internal capsule
postcentral gyrus (S1 cortex)
PROPRIOCEPTION: Central processes of the these CN V cells enter pontine region of the brain stem:
chief sensory nucleus of V - primary afferent synapse with 2o neurons
trigeminothalamic tract
ventral posterior medial (VPM) nucleus of thalamus - synapse with 3o neurons
posterior limb of internal capsule
postcentral gyrus
