ascending and descending tracts

Question 1

what is the end of the spinal cord (yellow part) called

Answer 1

conus medullaris

Question 2

what does the conus medullaris continue into

Answer 2

filum terminalis (connective tissue) which is anchored to the dorsum of coccyx

Question 3

what are the three layers of meninges around spinal cord

Answer 3

-dura
-arachnoid
-pia

Question 4

where is the lateral horn present

Answer 4

T1-L2,L3
(where you get preganglionic sympathetic fibres)

Question 5

what are these

Answer 5

lamina of rexed

Question 6

arteries of the spinal cord

Answer 6

Question 7

what is the space in between the dura and the bone in the spinal canal called

Answer 7

epidural space

Question 8

describe dorsal column-medial lemniscus pathway

Answer 8

1. First order neurones carry sensory information from peripheral nerves to the medulla oblongata
2. Within the medulla oblongata these fibres decussate (cross to the other side of the CNS); they then travel in the contralateral medial lemniscus to reach the thalamus
3. The third order neurones transmit the sensory signals from the thalamus to the ipsilateral primary sensory cortex of the brain

Question 9

is the dorsal column-medial lemniscal pathway a conscious or unconscious tract

Answer 9

conscious

Question 10

what does the anterior spinothalamic tract do

Answer 10

carries the sensory modalities of crude touch and pressure

Question 11

what does the lateral spinothalamic tract do

Answer 11

carries the sensory modalities of pain and temperature

Question 12

first order neurons in spinothalamic tract

Answer 12

-they arise from the sensory receptors in the periphery
-They enter the spinal cord, ascend 1-2 vertebral levels, and synapse at the tip of the dorsal horn (the substantia gelatinosa)

Question 13

second order neurons in the spinothalamic tract

Answer 13

-they carry the sensory information from the substantia gelatinosa to the thalamus
-After synapsing with the first order neurones, these fibres decussate within the spinal cord (cross segmentally), and then form two distinct tracts (AST and LST)

Question 14

third order neurons in spinothalamic tract

Answer 14

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

Question 15

what is pyramidal tract responsible for

Answer 15

fine, precise movement particularly of lower limb muscles

Question 16

tectospinal tract

Answer 16

• Input mostly to cervical segments
• Thought to mediate head and neck movement due to visual stimuli

Question 17

reticulospinal tract function

Answer 17

• Has many nuclei and receives input from virtually all parts of the CNS
• It has many functions, including the influencing of voluntary movement

Question 18

where does medial reticulospinal tract arise from

Answer 18

the pons

Question 19

where does lateral reticulospinal tract arise from

Answer 19

medulla

Question 20

is the anterolateral system a conscious or unconscious tract

Answer 20

conscious

Question 21

in the DCML, where do first order neurons travel with signals from the upper limb

Answer 21

travel in fasciculus cuneatus (lateral part of the dorsal column) then they synapse in the nucleus cutaneous of the medulla oblongata

Question 22

In the DCML, where do first order neurons with signals from the lower limb travel

Answer 22

they travel in the fasciculus gracilis (medial part of the dorsal column), then they synapse in the nucleus gracilis of the medulla oblongata

Question 23

where do second order neurons begin in the DCML

Answer 23

in the cuneate nucleus or gracilis

Question 24

what are the two tracts in the anterolateral system

Answer 24

-anterior spinothlamic tract
-lateral spinothalamic tract

Question 25

what info does the anterior spinothalamic tract carry

Answer 25

sensory modalities of crude touch and pressure

Question 26

what info does the lateral spinothalamic tract carry

Answer 26

sensory modalities of pain and temperature

Question 27

what do first order neurons in the anterolateral system do

Answer 27

-arise from the sensory receptors in the periphery
-enter the spinal cord
-ascend 1-2 vertebral levels
-synapse at the tip of the dorsal horn (substantia gelatinosa)

Question 28

what do second order neurons in the anterolateral system do

Answer 28

-carry sensory info from the substantia gelatinosa to the thalamus
-fibres decussate within the spinal cord and then form the anterior and the lateral tract
-these tracts then synapse within the thalamus

Question 29

what do third order neurons in the anterolateral system do

Answer 29

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

Question 30

what are the descending tracts

Answer 30

pathways by which motor signals are sent from the brain to the lower motor neurons

Question 31

what is the corticospinal tract responsible for (pyramidal tract)

Answer 31

fine, precise movement
-particularly of distal limb muscles

Question 32

what are the pyramids

Answer 32

tracts form visible ridges on the anterior surface of the medulla called pyramids

Question 33

where do most fibres of the corticospinal tract cross when they decussate

Answer 33

caudal medulla

Question 34

name the extra-pyramidal tracts

Answer 34

-tectospinal tract
-reticulospinal tract
-vestibulospinal tract

Question 35

vestibulospinal tract

Answer 35

excitatory input to antigravity extensor muscles

Question 36

where does vestibulospinal tract originate from

Answer 36

fibres originate in the vestibular nuclei of the pons and medulla