Dorsal Column Medial Lemniscus Flashcards
The pathway that lets you feel things
Dorsal Column/medial lemniscus
identifying object based on shape/texture
Sterognosis
drawing of number/letter on palm and all receptors are involved
graphesthesia
Trasmists sensation of light touch, pressure, vibration, proprioceptoin
Dorsal column/medial lemniscus
1st neuron of DC/ML is in
sensory ganglion w/ cell body in DRG
2nd neouron of DC/ML is in
sp cd or brainstem– will cross midline here and asencnd to thalamus
where does the DC/ML cross the midline
in the caudal medella
location of 3rd neuron in DC/ML
thalamus
Function of first neuron
peripheral process trasmits info from mechano–> Cell body in DRG
When central process leave DRG is ascends _______ with the dorsal columns
IPSILATERALLY
Where does the 1st neuron end?
terminates in dorsal column nuclie
2nd neuron cell body located
nucleas gracilic or nucleus cuneatus
Where does axon decussation occur for DC/ML
goes to contralateral side after synapsing on F.gracilis or cuneatus
After decussation on Fgracilis or F. cuneatous, axon ascends….
as the Medial Lemniscus
Level of brain the 2nd neuron axon synapses at
cuadal medulla on the F. cuneatus or F. Gracilis
F.Gracilis if for
pahtways form lower body
F. Cuneatus is for
pathways from upper body
Where does the 2nd neuron terminate
In the Ventral posterior lateral nucleus or VPL in the thalamus
where is the VPL located
thalamus
Where is the cell body of 3rd neuron
Cell body in the VPL of thalamus
Where do the axons pass through after then synapse on VPL
axons pass through posterior limb of internal capsule
Where does the 3rd neuron terminate
in the SI cortex (poscentral gyrus, primary somatosensory cortex
a cluster of NCB with lots of dif nuclei with lots of dif names
thalamus
Dorsal colum with axons below T7
fasiculus gracilis
Dorsal column with axons above T7
F. cuneatus
What gets added on latter, F. gracilis or cuneatus
F. cuneatus bc has from upper body
1st neuron: from sp cd to caudal medulla, where are the sacral dermatomes located
medially
lumbar, thoracic, cerical dermatomes are located progressively more ______ as we ascend from sp cd to caudal medulla
laterally
CC: unilateral sp cd lesion causes loss of what functions
light touch, pressure, vibration and proprioception on SAME SIDE of lesion from derms below level of lesion
as well as loss of other seosry and motor fnx
lesion here results in loss of lt, pressure, vb from derms below level of lesion on same side as well as loss of other sensory and motor function
unilateral (one side) spinal cord lesion
lesion on the left side of spinal cord in sacral region results in
loss of all touch, sensation, vibration and proproception and motor function on SAME SIDE of lesion
Bilateral sp cd lesion results in
loss of lt, pressure, vb from dermatomes just below level of lesion and loss of other sensory and motor
loss of light touch, pressure, vibration and proprioception from derms below level of lesion while other sensory and motor funx intact
Posterior cord syndome
Posterior cord sydrome results in:
loss of lt touch, pressure, vibration from derms below lesion while other sensory and motor functions are intact.
loss of lt, pressure, vb from dermatomes just below level of lesion and loss of other sensory and motor
(on both sides)
bilateral cord lesion or transecion
Large central cord syndrome
a. loss of light touch/pressure/ vibration/proprioception from derms below level of lesion
b. Sacral region may be spared because these guys head more lateral higher up we get
c. loss of sensory and motor fnx
a. loss of light touch/pressure/ vibration/proprioception from derms below level of lesion
b. Sacral region may be spared because these guys head more lateral higher up we get
c. loss of sensory and motor fnx
Large central cord syndrome
get sparing of sacral region, everything else below lesion is fucked
Large central cord syndrome
cell bodies in caudal medulla: F. gracilis or F. cunateus
2nd neuron
Axons decussate here as interal arcuate fibers
2nd neuron
After 2nd neurons decussate, they from axons called
medial lemniscus
Axons of medial lemniscus travel from ______ through these regions
caudal medulla
rostral medulla, pons and midbrain
Where does the medial lemniscus terminate in
VPL
At rostroal medullas, somatotopy
headless hemiman standing on pyramids
At level of pons, somatotopy
fibers from face added via trigeminal
and from lateral–center: SLTC
At the rostral medulla, what happens to sacral fibers
become more ventral
When can we add somatotopy of head
midpons or above
Lesion of Medial Lemniscus results in:
loss of lt touch/pressure/vibration from dermatomes BELOW level and on CONTRALATERAL side
loss of lt touch/pressure/vibration from dermatomes BELOW level and on CONTRALATERAL side
Lesion of Medial Lemniscus or Medial medullary syndrome
Thalamas has
VPL: for sensations from
VPM for sensations from
body
face
Somatotopy of Thalamus
add fibers from face in VPM anlong with VPL
face more medial==> legs more lateral in the thalamus
Where do the axons of the third neuron pass through
posterior limb of internal capsule
Axons from thalamus fan out in something called
corona radiata
Fibers from VPL and VPM head to
SI cortex
SI cortex somatotopy
think about face being big and outside laterally, while toward the central sulcus we have the legs and arms
Lesion of thalamus or SI cortex result in
loss of sensation from contralateral half of body
loss of sensation on right half of face, right half of body d/t
lesion in the contraleral half of thalmus or SI cortex
Area 3a for
limb movement
Area 3b for
basic tactile info, edges and texture
Area 1 for
motion and direction of movment of object
Area 2 for
limb position, shape of objects
SI neurons project to
SII cortex along upper border of sylvian fissure and insular cortex
where is SII cortex at
along upper border of sylvnain fissure and insular cortex
Where are Parieatal Association cortices located
intrapariatal sulcus
What do parietal association cortices do
recieve senosory info and project it to motor cortex
parietal association cortices are both:
unimodal and multimodal
lesion in unimodal part of Parietal Association cortices results in
agnosias (cant reconginze an object or property of object
Lesion here results in contralateral neglect
in Multimodal part of Parietal Association cortex
Region responsible for combining sensation with motivation, attention and relevance
Multimodal part of Parietal association cortex
Region for visual, auditory and somatorsensory input from SI or SII
Unimodal Parietal association Cortex
