Tracts

Question 1

What can ascending tracts be divided into

Answer 1

Conscious tracts

Unconscious tracts

Question 2

What are the unconscious ascending tracts

Answer 2

Spinocerebellar tracts

Question 3

What are the conscious ascending tracts

Answer 3

DCML

Anterolateral system

Question 4

What does the DCML carry

Answer 4

Sensory

• fine touch (tactile sensation)
• vibration
• proprioception

Question 5

Where in the spinal cord does information of the DCML travel

Answer 5

Dorsal (posterior) columns

Question 6

Where in the brainstem is the DCML information transmitted through

Answer 6

Medial lemniscus

Question 7

How do you remember the route of information for DCML

Answer 7

dorsal column

medial lemniscal

Question 8

How many groups of neurones are involved in the DCML

Answer 8

3

first
second
third order neurones

Question 9

DCML

What do first order neurones carry

Answer 9

Sensory information from peripheral nerves to medulla oblongata

Question 10

DCML

What are the two different pathways first order neurones can take

Answer 10

Signals from upper limb (T6 and above)
- travel to fasciculus cuneatus (lateral part of the dorsal column)
- synapse with the nucleus cuneatus of the medulla oblongata

Signals from the lower limb (below T6)
- travel to fasciculus gracilis (medial part of the dorsal column)
- synapse in the nucleus gracilis of the medulla oblongata

Question 11

DCML

What level are upper limb

Answer 11

T6 and above

Question 12

DCML

What level are lower limb

Answer 12

Below T6

Question 13

DCML

Where do signals from the upper limb travel

Answer 13

In fasciculus cuneatus - lateral part of the dorsal column

Question 14

DCML

Where do signals from the lower limb travel

Answer 14

In fasciculus gracilis - medial part of the dorsal column

Question 15

DCML

Where do signals from the upper limb synapse

Answer 15

Nucleus cuneatus of the medulla oblongata

Question 16

DCML

Where do signals from the lower limb synapse

Answer 16

Nucleus gracilis of the medulla oblongata

Question 17

DCML

Describe secondary order neurones

Answer 17

Begin in the cuneate nucleus or gracilis

Receives information from the preceding neurones - delivers it to the third order neurones in the thalamus

Question 18

DCML

Where do fibres decussate

Answer 18

Within the medulla oblongata

Then travel in the contralateral medial lemniscus to reach the thalamus

Question 19

DCML

Describe third order neurones

Answer 19

Transit sensory signals from the thalamus to the ipsilateral primary sensory cortex of the brain

Question 20

DCML

Describe the pathway of third order neurones

Answer 20

Ascend from the ventral posterolateral nucleus of the thalamus - travel through the internal capsule and terminate at the sensory cortex

Question 21

What are the two tracts of the spinothalamic

Answer 21

Anterior spinothalamic

Lateral spinothalamic

Question 22

Describe the anterior spinothalamic tract

Answer 22

Carries sensory modalities of crude touch and pressure

Question 23

What does the posterior spinothalamic tract carry

Answer 23

Carries sensory modalities of pain and temperature

Question 24

Spinothalamic

How many groups of neurones does the tract contain

Answer 24

3

First
Second
Third order neurones

Question 25

Spinothalamic Describe first order neurones

Answer 25

Arise from sensory receptors in the periphery Enter the spinal cord - ascend 1-2 vertebral levels Synapse at the tip of the dorsal horn

Question 26

Spinothalamic Where first order fibres synapse

Answer 26

1-2 vertebral levels up Synapse at the tip of the dorsal horn - called substantia gelatinosa

Question 27

Spinothalamic Describe the route of second order neurones

Answer 27

Carry sensory information from the substantia gelatinosa to the thalamus

Question 28

Spinothalamic Where do fibres decussate

Answer 28

Within spinal cord

Question 29

Spinothalamic Second order neurones Where do crude touch and pressure fibres enter

Answer 29

Anterior spinothalamic tract

Question 30

Spinothalamic Second order neurones Where do pain and temperature fibres enter

Answer 30

Lateral spinothalamic tract

Question 31

Spinothalamic What can anterior and posterior spinothalamic tracts be considered

Answer 31

Single pathway - tracts run alongside each other

Question 32

Spinothalamic Where do second order neurones synapse

Answer 32

Travel superiorly within the spinal cord Synapse in the thalamus

Question 33

Spinothalamic Describe third order neurones

Answer 33

Carry sensory signals from the thalamus to the ipsilateral primary sensory cortex of the brain

Question 34

Spinothalamic Describe the pathway of third order neurones

Answer 34

Ascend from the ventral posterolateral nucleus of the thalamus, travel through the internal capsule and terminate at the sensory cortex

Question 35

Where do corticospinal tracts begin

Answer 35

Cerebral cortex

Question 36

What inputs do corticospinal tracts receive

Answer 36

Primary motor cortex Premotor cortex Supplementary motor area Receive never fibres from the somatosensory area - play a role in regulating the activity of the ascending tracts

Question 37

Corticospinal tract What is the route of the neurones

Answer 37

Originate in the cortex Neurones converge Descend through the internal capsule Pass through crus cerebri of the mid brain, pons and into medulla most inferior (caudal) part of the medulla - tract divides into two

Question 38

Describe the internal capsule

Answer 38

White matter pathway Located between the thalamus and basal ganglia

Question 39

Corticospinal What does the tract divide into

Answer 39

Lateral corticospinal tract Anterior corticospinal tract

Question 40

Corticospinal tract Describe the fibres within the lateral corticospinal tract

Answer 40

Decussate Descend into the spinal cord Terminate at the ventral horn (at all levels) - lower motor neurones go from here

Question 41

Corticospinal tract Describe the fibres of the anterior corticospinal tract

Answer 41

Remain ipsilateral Descends into the spinal cord Decussate and terminate in ventral horn of cervical and upper thoracic segmental levels

Question 42

Corticospinal tract Where do fibres of the lateral corticospinal tract terminate

Answer 42

Ventral horn of all levels

Question 43

Corticospinal tract Where do fibres of the anterior corticospinal tract terminate

Answer 43

Ventral horn of the cervical and upper thoracic segmental levels

Question 44

Corticospinal tract Where do fibres of the lateral corticospinal tract decussate

Answer 44

Most caudal of the medulla

Question 45

Corticospinal tract Where do fibres of the posterior corticospinal tract decussate

Answer 45

Ventral horn of the cervical and upper thoracic segmental levels