Spinal Cord and Periphery

Question 1

where motor neuron crosses?

Answer 1

at the medulla

Question 2

what do all the axons of motor neurons pass through after beginning at the gyrus?

Answer 2

the internal capsule

Question 3

what part of the internal capsule do motor fibres pass through?

Answer 3

the posterior limb

Question 4

after passing through the internal capsule what do motor fibres enter?

Answer 4

the midbrain

Question 5

what is the crus cerebri?

Answer 5

the cerebral peduncle in the anterior part of the midbrain that is the motor fibres bypassing the thalamus from the midbrain.

Question 6

where do motor fibres sit in the pons?

Answer 6

the front part

Question 7

describe the course of an upper motor neuron from the gyrus to its synapse in the grey matter of the spinal cord

Answer 7

gyrus > posterior limb of the internal capsule > midbrain > cerebral peduncles to pons > medulla (decussation) > spinal cord grey matter synapse at level it exits

Question 8

what do ascending spinal tracts carry?

Answer 8

sensory information

Question 9

how many neurons are in the ascending spinal tracts?

Answer 9

3 (1st, 2nd and 3rd order neuron)

Question 10

in a sensory spinal tract which neuron will cross the spinal tract?

Answer 10

the 2nd neuron

Question 11

what sort of information does the dorsal column pathway carry?

Answer 11

> fine touch, tactile localisation, vibration sense and proprioception

Question 12

where does the 1st sensory neuron synapse in the dorsal column tract?

Answer 12

gracile and cuneate nuclei at the bottom of the medulla

Question 13

what sensory neuron crosses to the opposite side in the dorsal column tract?

Answer 13

the second sensory neuron

Question 14

what is the medial lemiscus?

Answer 14

sensory fibres from the posterior spinal cord that have synapsed in the medulla

Question 15

where does the 2nd order neuron take the sensory information in the dorsal column tract?

Answer 15

to the thalamus

Question 16

where does the 3rd order neuron take the sensation to and from in the dorsal column tract?

Answer 16

from the thalamus to the post central gyrus

Question 17

what is the thalamus?

Answer 17

a group of nuclei involved in the processing of sensory information through which all sensory information passes.
sensory relay station.

Question 18

what groups of nuclei make up the thalamus?

Answer 18

anterior
medial
lateral

Question 19

what sort of sensation is carried by the lateral spinothalamic tract?

Answer 19

pain and temperature

Question 20

where does the 1st order neuron synapse in the lateral spinothalamic tract end?

Answer 20

at the level it enters the spinal cord in the grey matter

Question 21

at what level does the lateral spinal tract cross the spinal cord?

Answer 21

at the level it enters

Question 22

if the lesion is above the level of the crossing is the deficit on the opposite or the same side?

Answer 22

the opposite

Question 23

if the lesion is below the level of crossing is the deficit on the same side or the opposite side?

Answer 23

the same side as the lesion

Question 24

someone has a paralysis of their right side with touch deficit but pain sensation is lost on their left. why?

Answer 24

this is because the lateral spinal tract crosses as it enters the spinal cord at a different level so the lesion is above the level of crossing but below the level of crossing for the dorsal spinal tract carrying touch sensation

Question 25

what is a reflex?

Answer 25

an involuntary stereotyped pattern of response brought about by a sensory stimulus.

Question 26

is the stretch reflex mono or polysynaptic?

Answer 26

monosynaptic to the muscle that is contracted but polysynaptic to an inhibitory neuron to the antagonist muscle causing it to flex (peciprocal innervation)

Question 27

how that the stretch reflex be affected if the upper motor neuron was damaged?

Answer 27

it would be present and exaggerated

Question 28

what would the affect of an upper motor neuron lesion be on the muscle?

Answer 28

spastic paralysis with hyperreflexia

Question 29

what would be effect be of a lesion of the upper motor neuron above the decussation?

Answer 29

contralateral spastic paralysis and hyperreflexia

Question 30

what would the effect be of a lesion of the upper motor neuron below the decussation?

Answer 30

ipsilateral spastic paralysis and hypereflexia

Question 31

what is the effect of a lower motor neuron lesion?

Answer 31

ipsilateral flaccid paralysis and areeflexia