Neurology 4

Question 1

what is the central tube in the middle of the spinal cord called?

Answer 1

central canal

Question 2

what type of neuron is affected when there is a lesion on the ventral motor neuron?

Answer 2

lower motor neuron

Question 3

what are the three columns that are present n the spinal cord?

Answer 3

anterior
lateral
posterior

Question 4

what are tracts?

Answer 4

myelinated axons pathways

Question 5

what are nucleii?

Answer 5

cell bodies in white matter (CNS)

Question 6

how many neurons are there between peripheral receptor and the cortex?

Answer 6

3

Question 7

where do the three neurons synapse from the peripheral receptor to the cortex?

Answer 7

receptor -> grey matter in spinal cord/medulla
(neuron then crosses over to the contralateral side)

medulla -> nucleus in contralateral thalamus

thalamus -> parietal cortex

Question 8

in which column of the spinal cord do sensory neurons travel in ?

Answer 8

posterior column

Question 9

how many neurons are involved in pain and temp. detection ?

Answer 9

3

Question 10

where do pain and temp. neurons cross over to the contralateral side?

Answer 10

at the same spinal level they entered

Question 11

where do sensory neurons cross over to the contralateral side ?

Answer 11

inferior to the pyramids of the medulla

Question 12

how many neurons are involved in motor descending tracts of the spinal cord?

Answer 12

2

Question 13

where do motor neurons originate from?

Answer 13

cerebral cortex and brain stem

Question 14

where do motor neurons cross over the to contralateral side?

Answer 14

pyramidal decussation in medulla

Question 15

in which column of the spinal cord do motor neurons travel down?

Answer 15

lateral column

Question 16

what are the two responsibilities of the lower motor neurons?

Answer 16

muscle tone

reflexes

Question 17

what happens to the reflex if the lower motor neurons are affected?

Answer 17

absent or reduced

Question 18

what happens to the reflex if the upper motor neurons are affected and lower motor neurons are intact?

Answer 18

reflexes and tone are exaggerated

Question 19

can reflexes be monosynaptic ?

Answer 19

yes

Question 20

is a reflex voluntary ?

Answer 20

no

Question 21

name a monosynaptic reflex

Answer 21

stretch reflex

Question 22

name a polysynaptic reflex

Answer 22

flexor reflex

Question 23

state a 6 stages of the stretch reflex

Answer 23

1. the tendon is stretched
2. intrafusal muscle fibres are stimulated
3. sensory neuron is stimulated
4. motor neuron is activated for the agonist and antagonist muscle
5. muscle is contracted and relaxed

Question 24

why are stretch reflexes important?

Answer 24

control muscle tone and posture

Question 25

during a stretch reflex do the neurons APs travel up to the CNS ?

Answer 25

no

- the neurons stay in the spinal level they entered at

Question 26

if someone wants to voluntarily contract a muscle do the neurons need to travel up to the CNS?

Answer 26

yes

Question 27

is muscle tone increased or decreased during sleep?

Answer 27

decreased

Question 28

are upper or lower motor neurons involved in the stretch reflex and flexor reflex?

Answer 28

lower motor neurons

Question 29

what happens to the reflexes if the upper motor neurons are damaged ?

Answer 29

the reflexes are exaggerated

Question 30

there is a lesion at C3 on the left side which results in the- pyramidal tract
spinothalamic tract and
posterior column
being abrupted on the left side.
what would be the sensory and motor lose?

Answer 30

Left side

• paralysis
• loss of touch and vibration
• reflexes are exaggerated

Right side
- loss of temp and pain sensation
(this is because pain/temp nerves cross to the contralateral side as soon as they enter the spinal cord )

Question 31

are autonomic responses voluntary ?

Answer 31

no

Question 32

how many neurons are there in the autonomic pathway ?

Answer 32

2

• preganglionic
• postganglionic

Question 33

what is the outflow of sympathetic and parasympathetic ?

Answer 33

sympathetic = thoracic-lumbar
parasympathetic = cranio-sacral

Question 34

what autonomic response has a long preganglionic neuron?

Answer 34

parasympathetic

Question 35

how many neurons are in ascending sensory tracts?

Answer 35

3

Question 36

how many neurons are in descending motor tracts ?

Answer 36

2