Spinal cord

Question 1

where is the dorsal/ posterior column and carries info from

Answer 1

it is found in the dorsal white matter, it carries information from- skin receptors, joint and muscle receptors (position sense), to the cortex

Question 2

motor descending (efferent) tracts

Answer 2

pyramidal tracts- lateral/anterior corticospinal tract

extrapyramidal tract- rubrospinal, reticulospinal, olivospinal, vestibulospinal tracts

Question 3

sensory and ascending (afferent) pathways

Answer 3

dorsal column medial lemniscus system, spinocerebellar tracts- anterior and posterior, anterolateral system- anterior and lateral spinothalamic tract

Question 4

2 sections of dorsal/ posterior colum

Answer 4

gracilis and cuneatus

Question 5

first order neuron- dorsal/ posterior column

Answer 5

this brings the signal from a receptor. the upper limb and upper chest use cuneatus and the lower limbs and trunk use gracilis

Question 6

second order neuron- dorsal/ posterior column

Answer 6

depending on the tract the first order neurone will synapse with a second order neuron at the gracile nucleus and the cuneate nucleus and the second order neuron crosses contralaterally @ the medulla and travels to thalamus

Question 7

third order neuron- dorsal/ posterior column

Answer 7

the second order neuron synapses with a third order neuron at the thalamus and the third order neurone travels to the primary somatosensory cortex

Question 8

spinothalamic tract

Answer 8

the tract runs from the spinal cord to the thalamus and then send signals to the cortex

Question 9

spinothalamic tract- 2 sections

Answer 9

lateral spinothalamic tract- carries pain and temperature sensation, anterior-spinothalamic tract- itch, tickle, pressure, vibrations, and crude, poorly localized touch sensation

Question 10

spinothalamic tract- first order neuron

Answer 10

a first order motor neuron brings the signal from a receptor, this is different as it synapses straight away and crosses at this level

Question 11

spinothalamic tract- second order neurone

Answer 11

this synapses with the first order neuron at the level of entry into the spinal cord. the second order neuron crosses to the opposite side of the spinal cord and then ascends to the thalamus

Question 12

spinothalamic tract- third order neurone

Answer 12

the second order neuron synapses with a third order neuron at the thalamus and this then travels to the primary somatosensory cortex

Question 13

spinocerebellar tract-

Answer 13

this tract runs from the spinal cord to the cerebellum. made up of 2 sections- posterior spinocerebellar tract, anterior spinocerebellar tract

Question 14

spinocerebellar tract- posterior spinocerebellar tract

Answer 14

this is an uncrossed tract (i.e. the fibres rises ipsilaterally) and enter the cerebellum via the inferior cerebellar peduncle
it does not cross at all and carries information at the same side

Question 15

spinocerebellar tract- anterior spino-cerebellar tract

Answer 15

this is a tract in which most fibres cross the spinal cord at entry level and then crosses back just before entering the cerebellum via the superior cerebellar peduncle. those fibres that do not cross at the level of entry to the spinal cord rise ipsilaterally and enter the cerebellum via the superior cerebellar peduncle

Question 16

what is the corticospinal tract

Answer 16

this tract originates at the cortex and then travels down directly to the spinal cord. the 2 sections- the lateral corticospinal tract, and the anterior corticospinal tract
this tract originates at the motor and premotor areas of the cortex (cell bodies are in the cortex and the axon travels down the spinal cord.

Question 17

corticospinal tract- the lateral corticospinal tract

Answer 17

this carries information essential for control of the extremities

Question 18

corticospinal tract- anterior corticospinal tract

Answer 18

this carries information essential for control of axial skeleton

Question 19

corticospinal tract- axon

Answer 19

the axon descends ipsilaterally via the cerebral peduncle and coverage into axon bundles (which a pyramidal in shape hence the name pyramidal tract) at the medulla oblongata

Question 20

corticospinal tract- what happens at the medulla oblongata

Answer 20

2 segments: 80-90% of the fibres cross to the contralateral side and descend as the lateral corticospinal tract to the respective level of spinal cord, the remaining 10-20% descend as the anterior corticospinal tract and then cross over at their respective level of spinal cord

Question 21

what is the reticulospinal tract

Answer 21

this indirect originates at the reticular formation and travels down to the spinal cord. there are 2 descending tracts lateral/ medial reticulo- spinal tract, it is difficult to identify a clearly demarcated pathway

Question 22

what do the medial/ lateral reticulospinal tract

Answer 22

LRT- facilitate the flexor reflexes and inhibits extensor reflexes and the MRT does the opposite

Question 23

what is the vestibulospinal tract

Answer 23

the tract originates at the lateral vestibular nucleus and ends at the spinal cord. the integration between the head and neck, the axial skeleton and the extremities is probably controlled by activity in this tract

Question 24

vestibulospinal tract- uncrossed tract

Answer 24

this is also an uncrossed tract (i.e. descends ipsilaterally). this tract helps coordinate the activity between the head and neck and the rest of the muscles in the axial skeleton and the limbs. the nerves in the tract are also essential for the modulation of reflex activities and balance

Question 25

what is the rubrospinal tract

Answer 25

the tract originates at the red nucleus (in brainstem) and ends at the spinal cord and is supposed to help with fine control of movement. it is not clear if this tract plays a significant role in humans. it is one of the fastest conducting neurones @120m/s

Question 26

rubrospinal tract- crossed

Answer 26

this is a crossed tract that crosses over at the origin (i.e. descends contralaterally), this tract could also provide the potential for indirect control of movements

Question 27

what is the spinal cord vital for

Answer 27

the spinal cord is vital for conveying and integrating sensory and motor information to and from the periphery

Question 28

what is a spinal cord lesion

Answer 28

a spinal cord lesion may impair motor, sensory, autonomic functions on size of damage, traumatic lesion- 84%

Question 29

example of non- traumatic lesions

Answer 29

degenerative disc diseases and spinal canal stenosis, spinal infracts, tumour, inflammation of spinal cord, viral infection, developmental/ congenital abnormalities

Question 30

what is a complete spinal cord lesion

Answer 30

a complete loss of function below the point of injury and outcome more predictable

Question 31

what is an incomplete spinal cord lesion

Answer 31

some spraining of neutral activity below the level of lesion, incomplete lesions are more common 55-65%, outcomes less predictable

Question 32

what are the vulnerable areas of the vertebral column

Answer 32

cervical spine (C5-C7)- 55% of all spinal cord injuries, thoracolumbar, typically T12, mid thoracic T4-7, majority of traumatic cases= fracture dislocation

Question 33

what is tetraplegia

Answer 33

this is impairment or loss of motor control and/ or sensory function is cervical segments of the cord- tetraplegia affects all 4 limbs

Question 34

what is paraplegia

Answer 34

this is impairment or loss of motor control and/ or sensory function in thoracic, lumbar or sacral segments of the cord- depending on level of injury, trunk and legs and pelvis may be involved