Anatomy: Ascending and Descending Tracts

Question 1

what modality are ascending tracts?

Answer 1

sensory

Question 2

two examples of ascending spinal tracts

Answer 2

1. dorsal column/ medial lemniscus tract (DCLM)

2. spinothalamic tract (STT)

Question 3

what does the DCLM tract sense?

Answer 3

fine touch and conscious proprioception

Question 4

where do fibres cross from the DCLM tract?

Answer 4

medulla so right side of the brain controls left side of the body

Question 5

where does the DCLM tract synapse?

Answer 5

thalamus and reaches the somatosensory cortex

Question 6

two divisions of the DCLM tract

Answer 6

1. cuneate fasciculus for upper body

2. gracile fasciculus for lower body

Question 7

role of the STT

Answer 7

pain, temperature and deep pressure

Question 8

where do fibres in the STT cross?

Answer 8

segmentally (ipsilateral control)

Question 9

where does the STT synapse?

Answer 9

posterior horn of the spinal cord

Question 10

what is the cortical motor homunculus?

Answer 10

parts of the body in the primary motor cortex

Question 11

examples of descending tracts

Answer 11

1. corticospinal tract (CST)
2. corticobulbar tract (CBT)
3. tectospinal tract
4. rubrospinal tract
5. reticulospinal tract
6. vestibulospinal tract

Question 12

what modality are descending tracts?

Answer 12

motor (arise from the motor cortex)

Question 13

role of the corticospinal tract (CST)

Answer 13

controls fine movement

Question 14

why is the CST a pyramidal tract?

Answer 14

tracts form visible ridges referred to as pyramids on anterior surface of the medulla

Question 15

two parts of the CST

Answer 15

1. lateral CST (pyramidal decussation) = limbs and digits

2. anterior/ ventral CST (segmental decussation) = trunk and posture

Question 16

which side of the body does the CST supply?

Answer 16

contralateral side

Question 17

what does the corticobulbar tract control?

Answer 17

muscles of face, head and neck

Question 18

what does the corticobulbar tract innervate?

Answer 18

bilateral innervation of cranial nuclei except CNXII and lower part of CNVII

Question 19

what does an UMN lesion of CNVII have?

Answer 19

forehead sparing

Question 20

what does a LMN lesion of CNVII have?

Answer 20

forehead involvement too

Question 21

four example of extrapyramidal motor tracts

Answer 21

1. tectospinal tract
2. rubrospinal tract
3. reticulospinal tract
4. vestibulospinal tract

Question 22

role of tectospinal tract

Answer 22

mediates head and neck movement to visual stimuli

Question 23

where does the rubrospinal tract arise from?

Answer 23

red nucleus of the midbrain

Question 24

role of the rubrospinal tract

Answer 24

excites flexors and inhibits extensors of the upper body

Question 25

location of the reticulospinal tract

Answer 25

central core of the brainstem

Question 26

role of the reticulospinal tract

Answer 26

excites extensors

Question 27

role of the vestibulospinal tract

Answer 27

input to anti-gravity extensor muscles