Pathways

Question 1

what are the ascending tracts responsible for

Answer 1

carrying sensory information from the peripheral nerves to the cerebral cortex

Question 2

what are the 3 ascending pathways

Answer 2

Dorsal Column-Medial Lemniscal (DCML)
Anterolateral Spinothalamic system
Spinocerebellar tract

Question 3

what is the unconscious tract

Answer 3

spinocerebellar

Question 4

what are the conscious tracts

Answer 4

DCML

Anterolateral Spinothalamic system

Question 5

what is the DCML pathway responsible for

Answer 5

fine touch
vibration
proprioception

Question 6

why is the DCML named as such

Answer 6

in the spinal cord, the sensation travels via the DORSAL COLUMNS
in the brainstem, it is transmitted through the MEDIAL LEMNISCUS

Question 7

what is the role of the first order neurones in the DCML pathway

Answer 7

carry sensory information from touch/proprioceptive receptors to the medulla oblongata

Question 8

how do signals from the upper and lower limb differ in the DCML pathway

Answer 8

signals from upper limb (to T5) travel in fasciculus coneatus

signals from lower limb (T6 and below) travel in fasciculus gracilis

Question 9

where is the fasciculus coneatus located in the dorsal column

Answer 9

laterally

Question 10

where is the fasciculus gracilis located in the dorsal column

Answer 10

medially

Question 11

where does the signal travelling via the fasciculus coneatus synapse

Answer 11

cuneate nucleus of the medulla oblongata

Question 12

where does the signal travelling via the fasciculus gracilis synapse

Answer 12

gracile nucleus of the medulla oblongata

Question 13

what begins in either the cuneate nucleus or gracilis

Answer 13

second order neurones

Question 14

where are the third order neurones found in the DCML pathway

Answer 14

thalamus

Question 15

where do the fibres decussate in the DCML pathway

Answer 15

medulla oblongata

Question 16

what does decussate mean

Answer 16

when the fibres cross over to the other side

Question 17

how to the second order neurones travel to the thalamus in the DCML pathway

Answer 17

they travel in the contralateral medial lemniscus

Question 18

where do the third order neurones in the DCML pathway take the sensory signals to

Answer 18

primary sensory cortex of the brain ascending through the ventral posterolateral nucleus

Question 19

what two tracts comprise the anterolateral system

Answer 19

anterior spinothalamic tract

lateral spinothalamic tract

Question 20

what sensory modalities is the anterior spinothalamic tract responsible for

Answer 20

crude touch

pressure

Question 21

what sensory modalities is the lateral spinothalamic tract responsible for

Answer 21

pain

temperature

Question 22

what is the tract of first order neurones in the anterolateral system

Answer 22

arise in sensory receptors in the periphery&raquo_space; enter spinal cord&raquo_space; ascend 1-2 levels&raquo_space; terminate at the tip of dorsal horn

Question 23

where do the neurones decussate in the anterolateral system

Answer 23

at the synapse of the first and second order neurones

Question 24

where do the second order neurones synapse with the third

Answer 24

thalamus

Question 25

how do third order neurones reach the primary sensory cortex from the thalamus

Answer 25

ventral posterolateral nucleus

Question 26

the spinocerebellar tracts are a collection of 4 pathways, what are they

Answer 26

Posterior spinocerebellar Cuneocerebellar Anterior spinocerebellar Rostral spinocerebellar

Question 27

what would a lesion of the DCML pathway cause

Answer 27

loss of proprioception and FINE touch

Question 28

if the lesion occurs in the spinal cord, what the sensory loss be (contra or ipsilateral) and why

Answer 28

ipsilateral fibres decussate at the medulla oblongata

Question 29

what will damage to the anterior and lateral spinothalamic tract cause

Answer 29

loss of pain and temperature sensation

Question 30

where would the sensory loss be in the anterolateral system and why

Answer 30

contralateral as fibres decussate within the spinal cord

Question 31

what is Brown-Sequard syndrome

Answer 31

hemisection of the spinal cord | one sided lesion

Question 32

what symptoms are seen in Brown-Sequard syndrome

Answer 32

ipsilateral loss of tactile sensation and proprioception (due to damage to DCML) contralateral loss of pain and temperature sensation (due to damage to anterolateral)

Question 33

what does injury to the spinocerebellar tract but why is this rarely seen

Answer 33

ipsilateral loss of muscle co-ordination | spinocerebellar pathways are unlikely to be damaged in isolation

Question 34

what normally accompanies injury to the spinocerebellar tract

Answer 34

injury to the descending motor tracts

Question 35

what are the descending tracts responsible for

Answer 35

pathways by which motor signals are sent from the brain to LMN

Question 36

what are the two major groups for descending pathways

Answer 36

pyramidal tracts | extrapyramidal tracts

Question 37

where do pyramidal tracts originate and where do they carry motor fibres to

Answer 37

- cerebral cortex | - spinal cord and brain stem

Question 38

what are pyramidal tracts responsible for

Answer 38

voluntary control of the musculature of the body and face

Question 39

where do extrapyramidal tracts originate and where do they carry motor fibres to

Answer 39

- brain stem | - spinal cord

Question 40

what are extrapyramidal tracts responsible for

Answer 40

involuntary and automatic control of all musculature | e.g. muscle tone, balance, posture

Question 41

what are there none of in the descending pathways which are seen in the ascending

Answer 41

synapses

Question 42

what are all neurones within the descending motor system called and why

Answer 42

Upper Motor Neurones as the neurones synapse with a Lower Motor Neurone

Question 43

where are the cell bodies of the UMN found

Answer 43

in the cerebral cortex or brain stem and their axon remain within the CNS

Question 44

what do the pyramidal tracts pass through

Answer 44

the medullary pyramids of the medulla oblongata

Question 45

what are the two pyramidal tracts

Answer 45

corticospinal tracts | corticobulbar tracts

Question 46

what is the corticospinal tract responsible for

Answer 46

supplying the musculature of the body | fine, precise movement of distal limb muscles

Question 47

what is the corticobulbar tract responsible for

Answer 47

supplying the musculature of the head and neck

Question 48

where does the corticospinal tract originate and where does it descend too

Answer 48

- cerebral cortex | - internal capsule

Question 49

what is the internal capsule

Answer 49

white matter pathway located between the thalamus an the basal ganglia

Question 50

what is the internal capsule susceptible to

Answer 50

compression from haemorrhage bleeds | = known as "capsular stroke"

Question 51

what differs between the lateral and anterior (ventral) corticospinal tract

Answer 51

lateral decussates in the medulla | anterior (ventral) decussate and terminate in the ventral horn of the cervical/upper thoracic segmental levels

Question 52

where does the corticobulbar tract arise from

Answer 52

lateral aspect of the primary motor cortex

Question 53

where do the fibres in the corticobulbar tract travel to

Answer 53

the brainstem

Question 54

where do the extrapyramidal tracts originate

Answer 54

in the brainstem

Question 55

what are the extrapyramidal tracts responsible for

Answer 55

involuntary/automatic control | muscle tone, balance, posture, locomotion

Question 56

what are the 4 extrapyramidal tracts

Answer 56

vestibulospinal reticulospinal rubrospinal tectospinal

Question 57

what are the signs of a lesion in the upper motor neurones

Answer 57

``` hypertonia hyperreflexia clonus babinski sign muscle weakness ```

Question 58

where does the primary motor cortex sit

Answer 58

in the pre central gyrus

Question 59

what symptoms are seen in Brown-Sequard's Syndrome

Answer 59

ipsilateral spastic paralysis ipsilateral hyper-reflexia and extensor plantar reflex ipsilateral loss of vibration and proprioception contralateral loss of pain and temperature

Question 60

where are the 1st 2nd and 3rd order neurone located in the Trigeminal system

Answer 60

1st - trigeminal sensory ganglion 2nd - chief sensory nucleus (general tactile stimuli) or spinal nucleus (pain, temp, info) 3rd - ventroposteriomedial (VPM) nucleus of the thalamus