Somatosensory I Flashcards
Function of PCMLS
discriminative touch, flutter vibration, proprioception
Function of trigeminothalamic pathway
crude touch, thermal sensation, nociception
What do large diameter fibers relay
discriminative touch, flutter vibration and proprioception
What vascular structures supply the VPL and VPM
thalamogeniculate branches of posterior cerebral artery
What can happen if posterior cerebral artery is occluded
Loss of all tactile sensation over the contralateral body and head
What does VPL receive info from
medial lemniscus
What target VPL shell
pacinian and joint/muscle input
Where do VPL third order neurons terminate
Primary S1 and secondary S2 somatosensory cortices
What is S1 made of
postcentral gyrus and posterior paracentral gyrus
What supplies the S1 cortical area
Anterior and MCA
What do ACA lesions do for S1
Affect contralateral lower limb
What do MCA lesions do for S1
Tactile loss over contralateral upper body and face
What are the subdivisions of S1
3a and b, 1 and 2
Where is S2
deep in inner face of upper bank of lateral sulcus
What does S2 represent
body surface
What is agnosia caused by
lesions in parietal association area
What is agnosia
contralateral body parts lost from body map, limb is not recognized as part of body
Function of spinocerebellar pathways
propioceptive and limited cutaneous info to cerebellum, so joint angles and limb position. Role in guiding control of body muscle tone, movement an posture
Function of Trigeminal n
sensory n. for head; muscles of mastication
Where does Trigeminal n. attach on brainstem
adjacent roots on ventrolateral aspect of pons
Four parts of trigeminal nuclei
main sensory nucleus
trigeminal motor nucleus
spinal nucleus
mesencephalic nucleus
Function of main sensory nucleus of CN V
touch and pressure
Function of trigeminal motor nucleus
muscles of mastication
Function of spinal nucleus of CN V
pain and temperature
Function of mesencephalic nucleus
proprioceptive afferents from TMJ and masticatory m.
What are the two parts of the main sensory nucleus
dorsomedial division: oral cavity
ventrolateral division: afferents from V1-V3
Where do second order fibers of ventrolateral division project
contralaterally via trigeminothalamic tract
Where do second order fibers of dorsomedial division project
ipsilateral vai trigeminothalamic tract
What plays a role in the jaw-jerk reflex
mesencephalic nucleus
Function of Pars interpolaris
proprioceptive input from jaw related to chewing and jaw placement
