Oct2 M2-Block J Introduction (lecture not tested)

Question 1

ganglion def

Answer 1

neuronal cell bodies group in PNS (autonomic ganglia, cranial nerve ganglia)

Question 2

nucleus def

Answer 2

neuronal cell bodies group in CNS (facial nerve nucleus for ex)

Question 3

nerve def

Answer 3

bundle of axons in the PNS (facial nerve)

Question 4

tract def

Answer 4

bundle of axons in the CNS (corticospinal tract, is one tract containing the axons of UMNs)

Question 5

LMN cell bodies are where

Answer 5

either

• in nucleus of a cranial nerve
• in grey matter (anterior horn) of the spinal cord

Question 6

orders of neurons for sensory system

Answer 6

• first order sensory neuron (sensory neuron of PNS)

- second order sensory neuron (further carries initial info coming from periphery first order sensory neuron towards CNS

Question 7

how a reflex works

Answer 7

• first order sensory neuron enters at posterior root (note: the posterior root also has a posterior root ganglion)
• it then synapses in grey matter of spinal cord on 3 types of neurons: excitatory interneurons, inhibitory interneurons and second order sensory neurons (go up in a tract up to the brain to lead to conscious awareness and decisions. multiple synapses there so slow)

Question 8

what interneurons do

Answer 8

-synapse with a LMN in the anterior horn of the spinal cord, which will go to periphery

Question 9

are interneurons in PNS or CNS

Answer 9

CNS

Question 10

are parts of first order sensory neuron + parts of LMN that are in spinal cord in PNS or CNS

Answer 10

PNS

Question 11

brain vs spine white and grey matters

Answer 11

• brain = grey outside white matter inside

- spinal cord = grey matter inside white matter outside

Question 12

when a first order sensory neuron receives danger (pain, temp, etc.) signal from leg, what happens

Answer 12

• flexors of ipsilateral leg contract (to go away form danger). EIs excite them and IIs inhibit the extensors in that leg
• extensors of contralateral leg contract (to maintain balance). EIs inhibit them. IIs inhibit the flexors of that contralateral leg.

Question 13

what can happen later after the reflex withdrawal and maintaining stance

Answer 13

UMNs in cortex can send APs down to specific muscles to readjust your position (synapse on LMNs in cranial nerve nuclei in brainstem + in anterior horn of spinal cord)

Question 14

radiology vs pathology orientation

Answer 14

• pathology = they put the real right on the right of the microscopy tray so you see the image as it is (right on right, left on left, dorsal on top, ventral on bottom)
• radiology: see the brain as if supine patient lying on their back and you look from their feet (right on left, left on right, dorsal on bottom, ventral on tom)

Question 15

name of LMN facial nerve (is CN VII) lesion

Answer 15

Bell’s palsy

Question 16

facial nerve nucleus components

Answer 16

• 2 nuclei (right and left) controlling forehead muscle contraction = go to left and right side of forehead
• 2 nuclei (right and left) controlling the rest of the facial muscles = ONLY go to their contralateral muscles
• so if pt can still contract forehead, know the pathology is ONE SIDED (stroke for example)*