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neuroanatomy > Somatosensory & Visual Pathways > Flashcards

Somatosensory & Visual Pathways Flashcards

1
Q

where are sensory cell bodies located? what kind of cells are they?

A

in the dorsal root ganglion or trigeminal ganglion
pseudounipolar

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2
Q

what size are axons for fine touch?

A

thick axons

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3
Q

what size are axons for pain and temp?

A

thin axons

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4
Q

what are proprioceptors?

A

muscle spindle organ - supports contraction
Golgi tendon organs - allows for stretching of muscle

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5
Q

what are proprioceptor axons like? what kinds of fibers are they?

A

large diameter & myelinated
A-alpha fibers travel ~80-120 m/s

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6
Q

what are mechanoreceptors?

A

meissner’s corpuscles and Merkel’s cells - texture and superficial sensation
Ruffini’s corpuscles - deep pressure
pacinian corpuscles - vibration

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7
Q

what are mechanoreceptor axons like? what kinds of fibers are they?

A

medium diameter & myelinated
A-beta fibers travel ~35-90 m/s

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8
Q

what are pain and temp receptors?

A

bare nerve endings (cold/heat/nociceptive)

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9
Q

what are bare nerve ending axons like? what kinds of fibers are they?

A

small diameter
A-delta fibers (myelinated) ~5-40 m/s
C fibers (unmyelinated) ~0.5-2 m/s

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10
Q

what is somatotopic organization like in the spinal cord?

A

more proximal parts of the body will be closer to the grey matter
continues into the posterior limb of internal capsule

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11
Q

what is the somatosensory cortex layout like?

A

similar to motor cortex

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12
Q

what is the ventral posterior medial thalamic nuclei important for?

A

sensation related to the face

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13
Q

what is the ventral posterior lateral thalamic nuclei important for?

A

sensation related to the body

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14
Q

what is the medial dorsal thalamic nuclei important for?

A

emotional processing of pain

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15
Q

what does the dorsal column/medial lemniscus pathway carry

A

fine touch, vibration, conscious proprioception of body

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16
Q

dorsal column/medial lemniscus pathway

A

1st neuron travel through fasciculus gracilis/cuneatus
synapses on 2nd neuron in nucleus gracilis/cuneatus
crosses midline in internal arcuate fibers in medulla
travel through medial lemniscus to synapse on 3rd neuron in ventral posterior lateral nucleus
travels through posterior limb of internal capsule to post central gyrus

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17
Q

what does the trigeminal lemniscus pathway carry

A

fine touch and vibration of face

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18
Q

trigeminal lemniscus pathway

A

1st neuron comes through CN V to synapse on main trigeminal sensory nucleus
2nd neuron crosses midline in pons, travels through trigeminal lemniscus to ventral posterior medial nucleus to synapse on 3rd neuron
travels through posterior limb of internal capsule to post central gyrus

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19
Q

what does the mesencephalic trigeminal nucleus contribute to? where are its cell bodies?

A

conscious proprioception of the face
cell bodies are in midbrain

20
Q

face proprioception pathway
reflexes

A

first neuron cell bodies are in mesencephalic trigeminal nucleus
synapses on principle sensory nucleus with second neuron
follows trigeminal lemniscus pathway
reflexes are transmitted through trigeminal motor nucleus

21
Q

what does the anterolateral system carry? what are the fibers like?

A

crude touch, pain, temperature of body
small diameter fibers

22
Q

anterolateral system pathway

A

neurons travel in dorsolateral fasciculus and ascend/descend 1 or 2 levels before synapsing on dorsal horn
neuron crosses midline in the anterior white commissure to travel in the anterolateral system to synapse on ventral posterior lateral nucleus
neuron travels to the post central gyrus (general) or cingulate gyrus/insula (emotional)

23
Q

what is the emotional pain response?

A

pain from the body or head can create an emotional response

24
Q

emotional pain response pathway

A

follows the anterolateral system
gives branches to the reticular formation
synapses in medial dorsal and ventral medial posterior nucleus
terminates in the limbic system (amygdala, insular cortex, cingulate cortex)

25
Q

what does the trigeminothalamic tract carry?

A

crude touch, pain, and temp of head

26
Q

trigeminothalamic tract pathway

A

1st neuron descends through the spinal trigeminal tract, synapses on the spinal trigeminal nucleus
2nd neuron crosses and travels through the trigeminothalamic tract to the ventral posterior medial nucleus

27
Q

spinal trigeminal nucleus and tract location
anterolateral system location in medulla
what would a lesion here cause?

A
28
Q

trigeminal and medial lemniscus location
anterolateral location in caudal pons

A
29
Q

trigeminal and medial lemniscus location
anterolateral location in rostral pons

A
30
Q

trigeminal and medial lemniscus location
anterolateral location in midbrain

A
31
Q

what is the retina?

A

layer of the eye containing neurons of the visual system
part of the diencephalon

32
Q

what are the layers of the retina?

A

nerve fiber layer
ganglion cell layer
inner plexiform layer
inner nuclear layer
outer plexiform layer
outer nuclear layer
photoreceptor layer
pigmented layer

33
Q

what does the pigmented layer do?

A

helps protect the photoreceptors from excess exposure to light

34
Q

what does the nerve fiber layer do?

A

forms the optic nerve at the optic disc

35
Q

what is contained in the outer nuclear layer?

A

cell bodies

36
Q

what does the outer plexiform layer do?

A

axon communication with inner nuclear layer

37
Q

rods vs cones

A

low light, periphery
color, high light, central retina

38
Q

what is special about the optic disc

A

blind spot, central retinal artery passed through here
nerve fiber layer axons pass here to become the optic nerve

39
Q

what is the fovea

A

where there is the highest acuity, central vision
only cones here
inner layers are gathered around the edge of the foveal pit

40
Q

how many layers of the lateral geniculate nucleus are there?

A

6, grouped in bilateral pairs
switch between ipsilateral and contralateral

41
Q

first two layers of lateral geniculate nucleus

A

magnocellular layers that deal with motion and spatial analysis

42
Q

layers 3-6 of the lateral geniculate nucleus

A

parvocellular layers that deal with color and shape

43
Q

input and output of the magnocellular layers

A

input: retinal ganglion parasol cells
output: primary visual cortex, layer 4

44
Q

input and output of the parvocellular layers

A

input: retinal ganglion midget cells
output: primary visual cortex, layer 4

45
Q

where is the primary visual cortex? how is it organized?

A

surrounds the calcarine sulcus
retinotopic organization, central vision located most posteriorly

46
Q

where is the secondary visual cortex?

A

surrounds the primary cortex

47
Q

circadian rhythm regulation

A

suprachiasmatic nucleus (SCN) regulates, based on light input from the retina
projections from the optic chiasm synapse in the SCN

neuroanatomy (14 decks)

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