Ascending and Descending tracts

Question 1

What modality are ascending tracts

Answer 1

Sensory

Question 2

What modality are descending tracts

Answer 2

Motor

Question 3

What is the DCML

Answer 3

Dorsal Column Medial Lemniscus tract

Question 4

What sensation does the DCML detect

Answer 4

fine touch

conscious proprioception

Question 5

Where do fibres in the DCML tract cross over to the contralateral side

Answer 5

2nd order nerves cross over at the level of the medulla

Question 6

What is the dorsal column in the spinal cord made up of

Answer 6

fasiculus gracilis

fasiculus cuneatus

Question 7

From where does the nucleus gracilis carry information

Answer 7

Legs

Question 8

From where does the nucleus cuneatus carry information

Answer 8

arms

Question 9

What is the STT

Answer 9

Spinothalamic tract

Question 10

What sensation does the STT detect

Answer 10

pain
temperature
crude touch / deep pressure

Question 11

Where do fibres in the STT cross over to the contralateral side

Answer 11

2nd order neurons cross over segmentally at the level they enter the spinal cord

Question 12

What action does the corticospinal tract help control

Answer 12

fine motor movement

Question 13

What is the corticospinal tract also known as (CST)

Answer 13

pyramidal tract

Question 14

what kinds of corticospinal tracts are there

Answer 14

lateral and ventral

Question 15

_% fibres cross over __ in the lateral CST

Answer 15

85% fibres cross over the midline at the decussation of the pyramids in the medulla

Question 16

where do fibres in the ventral CST cross over

Answer 16

segmentally in the spinal cord as they need to leave

Question 17

What is the internal capsule

Answer 17

deep subcortical tissue of white matter, all modalities run through this

Question 18

Give examples of extra-pyramidal tracts

Answer 18

tectospinal - input to H+N region
reticulospinal - reticular formation at core of brainstem (pons and medulla): consciousness, breathing, cariac
vesticulospinal - input to anti-gravity muscles

Question 19

What is Brown Séquard syndrome

Answer 19

hemisection of the spinal cord resulting in:
ipsilateral loss of fine touch, proprioception and fine movement (DCML + CST)
contralateral loss of pain and temperature (STT)

Question 20

Where is the primary somatosensory cortex found

Answer 20

post central gyrus

Question 21

Where is the primary somatomotor cortex found

Answer 21

pre central gyrus

Question 22

How many neurons are involved in ascending tracts

Answer 22

3

1st, 2nd and 3rd order neurons

Question 23

How many neurons are involved in descending tracts

Answer 23

2

UMN + LMN

Question 24

Where do 3rd order neurons in ascending tracts synapse

Answer 24

thalamus in the brain

Question 25

path of the corticobulbar tract

Answer 25

passes through internal capsule to reach the brainstem

Question 26

fibres in the corticobulbar tract innervate CN nuclei bilaterally except __

Answer 26

CN VII UMN of facial nerve has contralateral innervation of muscles of the lower face and bilateral innervation of muscles of the upper face ie R brain controls left lower facial muscles CN XII UMN of hypoglossal has contralateral innervation to the tongue

Question 27

central lesion of CN VII causes forehead sparing/involvement | and give an example of this

Answer 27

sparing because upper facial muscles have bilateral innervation stroke

Question 28

peripheral lesion of CN VII causes forehead sparing/involvement and give an example of this

Answer 28

involvement | Bell's palsy

Question 29

what is the rubrospinal tract

Answer 29

originates in the red nucleus of the midbrain excites upper limb flexors inhibits upper limb extensors

Question 30

the rubrospinal tract innervates both upper and lower limbs, true or false

Answer 30

FALSE | only innervates upper limbs

Question 31

what is the reticulospinal tract

Answer 31

originates in pons/medulla | excites upper and lower limb extensors

Question 32

in terms of descending tracts, what is the order of dominance over the body

Answer 32

1. corticospinal tract 2. rubrospinal tract 3. reticulospinal tract

Question 33

what happens if the CST is lost

Answer 33

rubrospinal tract is next dominant | therefore upper limb flexion ie decorticate posturing

Question 34

what happens is the rubrospinal tract is lost

Answer 34

reticulospinal tract is next dominant | therefore there is both upper and lower limb extension ie decerebrate posturing

Question 35

fasciculus gracilis is from below/above T6

Answer 35

below