Module D-03 Flashcards
Describe the 3 neuron chain spinal touch pathway
- 1st order neuron (somatosensory receptor neuron): afferent fibers in peripheral nerve (pseudounipolar with cell body in dorsal root ganglia) enter through dorsal roots
- 2nd order neuron: fibers crossing the midline(at cuneate or gracile nuclei) and terminating in the thalamus
- 3rd order neuron: fibers running in posterior limb of internal capsule and ending in S1 (primary somatosensory cortex)
Where does the pathway for touch and vibration start ?
on the body surface (dermatomes)
Where does the pathway for proprioception start?
on muscles
Where are the cell bodies of the 2nd order neurons found?
Cuneate and Gracilis nuclei
Which order fibers cross over in Touch pathway?
2nd order neurons
Which nucleus of the thalamus do the 2nd order touch neurons synapse?
ventral posterior lateral (VPL) nucleus
Where is the primary somatosensory cortex located?
postcentral gyrus of the parietal lobe and the part of the paracentral lobule on the medial side
From Where does input of the trigeminal pathway for
touch, vibration and proprioception come?
cutaneous mechanoreceptors and muscle proprioceptors of the face
Where are the cell bodies for the primary afferent neuron found?
Trigeminal ganglion
Describe the 3 neuron pathway for the trigeminal pathway
1) primary afferent fibers enter the brainstem at the pons and synapse in the principal (chief) sensory nucleus of CN V in upper half of the pons
2) second order neurons fibers exit the principal nucleus of CN V and immediately cross over to the contralateral side, where they ascend in the ventral trigeminothalamic tract and synapse in the ventral posterior medial (VPM) nucleus of the thalamus.
3) Third order neurons in the VPM nucleus of the thalamus send their axons through the posterior limb of the internal capsule, close to the genu, and then through the corona radiata then synapse in the primary somatosensory cortex
(S1).
What part of the brainstem are the fibers for somatosensory information of touch, vibration and proprioception from the face found?
Upper Pons and midbrain
Name the 4 nuclei of the Trigeminal
1) Principal (chief) nucleus
2) Spinal nucleus of V
3) Motor nucleus of V
4) Mesencephalic nucleus of V ( in midbrain)
Which brodmann’s areas make up the Primary somatosensory cortex
3,1,2
Somatotopic map
the somatosensory Homonculus , shows where on the primary somatosensory cortex is which part of the body’s sensation
Sensation of which regions of the body are found on the Lateral side of the primary somatosensory cortex?
from top to bottom: Trunk Arm Hand Fingers Upper Face Lower Face
