Spinal cord and the Periphery

Question 1

what information is carried in the descending cords of the spinal tract

Answer 1

motor

Question 2

where do the descending spinal tracts originate

Answer 2

cerebral cortex and brainstem

Question 3

what are the descending tracts concerned with

Answer 3

control of movement, muscle tone, spinal autonomic functions

Question 4

what happens to the descending and ascending tracts in the medulla

Answer 4

decussate to the opposite side

Question 5

how many neurons are in the descending pathway

Answer 5

2

Question 6

what information if carried in the ascending cords of the spinal tract

Answer 6

sensory

Question 7

how many neurones are in the ascending pathway

Answer 7

3

Question 8

what information is carried by the posterior/dorsal column

Answer 8

fine touch, tactile localisation, vibration sense, proprioception

Question 9

where does information in the dorsal column cross over

Answer 9

upper medulla - pyramidal tracts

Question 10

what is the main role of the thalamus

Answer 10

it is a sensory relay station (lateral nucleii)

Question 11

what information is carried by the lateral spinothalamic tract

Answer 11

pain and temperature

Question 12

where does information in the lateral spinothalamic tract cross over

Answer 12

at the level of entry

Question 13

if a lesion occurs above the level of crossing over of tracts where is the deficit

Answer 13

the opposite side

Question 14

if a lesion occurs below the level of the crossing over of tracts where is the deficit

Answer 14

on the same side

Question 15

what is a reflex

Answer 15

an involuntary stereotyped pattern of response brought about by sensory stimuli

Question 16

what are spinal reflexes

Answer 16

reflexes mediated at the level of the spinal cord

Question 17

anatomically what are the two types of reflex

Answer 17

monosynaptic - eg stretch reflex

polysynaptic - eg flexor relfex

Question 18

describe briefly what occurs in the stretch reflex

Answer 18

1. tendon stretched
2. intrafusal muscle fibres stimulated
3. sensory neuron activated

4a. monosynaptic arc
4b. polysynaptci arc to inhibitory interneuron

5a. muscle contraction
5b. reciprocal innervation

Question 19

what is the stretch reflex important in the control of

Answer 19

muscle tone and posture

Question 20

what mediates both the stretch and flexor reflexes

Answer 20

lower motor neuron

Question 21

what happens to the stretch reflex in upper motor neuron lesions

Answer 21

exaggerated

reflex control by lower motor neuron so if upper motor neuron lesion - reflex not affected - becomes exaggerated

muscle tone also increases = spasticity

Question 22

what are presentations of upper motor neuron lesions

Answer 22

spastic paralysis with hyperreflexia

Question 23

what does the corticospinal/pyramidal tract control

Answer 23

voluntary skilled movements

Question 24

is motor neurone disease an upper or lower motor neurone condition

Answer 24

lower motor neurone (= ventral horn of the spinal cord)

Question 25

what happens in motor neuron disease

Answer 25

neuron dies - muscle supplied by it atrophies

progressive, incurable disease

Question 26

what does an UMN lesion ABOVE the decussation of the corticospinal/pyramidal tract cause

Answer 26

contralateral spastic paralysis

hyperreflexia

Question 27

what does an UMN lesion BELOW the decussation of the corticospinal/pyramidal tract cause

Answer 27

ipsilateral spastic paralyis

hyperreflexia

Question 28

what does a LMN lesion of the corticospinal/pyramidal tract cause

Answer 28

ipsilateral flaccid paralysis

arreflexia

Question 29

what does a lesion ABOVE the decussation of the posterior/dorsal column cause

Answer 29

contralateral sensory loss

Question 30

what does a lesion BELOW the decussation of the posterior/dorsal column cause

Answer 30

ipsilateral sensory loss

Question 31

what would the lateral spinothalamic tract of the RIGHT side carry

Answer 31

pan and temp from the LEFT side of the body

vice versa

Question 32

what would the posterior/dorsal column of the RIGHT side carry

Answer 32

touch, pressure, proprioception from the RIGHT side of the body

vice versa

Question 33

what would lesions in the lateral spinothalamic tract cause

Answer 33

both lesion would be ABOVE the decussation (cross at spinal level of entry) so pain and temp lost on the opposite side to lesion

Question 34

CASE EXAMPLE: Brown-Sequard syndrome

eg herniated disc (left side) of C3

= hemisection of the spinal cord on left side

what tracts would be abrupted and where

Answer 34

Pyramidal tract, spinothalamic tract, posterior column

all abrupted on left side

Question 35

CASE EXAMPLE: at the spinal cord level, are the abrupted tracts affected above or below their crossing

Answer 35

Pyramidal tract = below crossing

Spinothalamic tract =  above crossing

Posterior column = below crossing

Question 36

CASE EXAMPLE: what does the pyramidal tract hemisection cause

Answer 36

left ipsilateral spastic paralysis

UMN lesion
below crossing

Question 37

CASE EXAMPLE: what does the spinothalamic tract hemisection cause

Answer 37

right contralateral loss of pain and temp

lesions will always be above crossing

Question 38

CASE EXAMPLE: what does the posterior column hemisection cause

Answer 38

left sided ipsilateral loss of touch and vibration sense

below crossing

Question 39

CASE EXAMPLE: what will happen to the reflexes

Answer 39

pyramidal tract UMN lesion below decussation

= hyppereflexia on left ipsilateral side