NS 6 - pathways - ascending

Question 1

name the two pathways to the cerebral cortex

Answer 1

dorsal column and the anterolateral system

Question 2

describe ascending tracts

Answer 2

neural pathway by which sensory info from the peripheral nerves is transmitted to the cerebral cortex

Question 3

which tracts are compromised of the dorsal column and the anterolateral system?

Answer 3

conscious tracts

Question 4

which tracts are comprimised of spinocerebellar tracts?

Answer 4

unconscious

Question 5

which sensory modalities does the dorsal column-medial lemniscal pathway carry?

Answer 5

fine touch, vibration and proprioception

Question 6

where does the DCML pathway occur?

Answer 6

in spinal cord travels via dorsal columns

in the brain stem it is transmitted through medial lemniscus

Question 7

first order neuron carries which sensory information (DCLM)

Answer 7

touch, proprioception or vibration from the peripheral nerves to medulla oblongata

Question 8

where do the signals from the upper limb (T6 and above) travel?
(first order neuron)

Answer 8

in the fasciculus cunneatus (lateral part of dorsal column) they then synapse in the medulla

Question 9

where do signals from the lower limb (below T6) travel? (first order neuron)

Answer 9

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

Question 10

where do 2nd order neurons begin? (DCLM)

Answer 10

either in nucleus gracilis or cuneate

Question 11

what is the main job of 2nd order neurons?

Answer 11

the fibres recieve info from the preceding neurons and delivers it to the 3rd order neurons in the thalamus
- within the medulla oblongata these fibres cross to the other side of the CNS, they then travel in the contralateral medial lemniscus to reach the thalamus

Question 12

describe the conus medullaris?

Answer 12

the lower extremity of the spinal cord

Question 13

describe the filum terminale

Answer 13

a delicate strand of fibrous tissue preceding from the apex of the conus medullaris

Question 14

describe the cuada equina

Answer 14

bunch of spinal nerves found at the bottom third of the spinal cord

Question 15

Name the two types of spinothalamic tract

Answer 15

anterior and lateral

Question 16

what sensory modalities do the anterior spinothalamic tract carry?

Answer 16

crude touch and pressure

Question 17

what sensory modalities does the lateral spinothalamic tract carry?

Answer 17

pain and temperature

Question 18

dorsal column pathway - Leg details…

Answer 18

1. First neuron leg fibres in gracile tract (Spinal Cord)
2. 2nd neuron in gracile nucleus (medulla) (crosses to medial)
3. 2nd neuron continues in medial lemniscus
4. third neuron continues to cerebral cortex (post central gyrus

Question 19

Dorsal Column - Arm details

Answer 19

1. first neuron arm fibres in cuneate tract (spinal tract)
2. second neuron in cuneate nucleus crosses midline (medulla)
3. 2nd neuron continues in medial lemniscus
4. third neuron continues to cerebral cortex - post central gyrus

Question 20

is the anterolateral tract an ascending tract?

Answer 20

yes

Question 21

which sensations does the anterolateral tract provide?

Answer 21

coarse touch, localised pain, temperature, itch

Question 22

where are the anterolateral tracts located?

Answer 22

white matter

Question 23

describe the anterolateraltract in terms of neurons

Answer 23

1. finger touches hot water
2. 1st neuron in spinal cord
3. 2nd neuron posterior horn (crosses to opposite side close to same level in white commissure ascends to thalamus)
4. third neuron synapses in thalamus and then projects to cerebral cortex

Question 24

name the two types of pain?

Answer 24

Discriminative ‘‘localising pain’’ and affective ‘‘suffering pain’’

Question 25

describe affective pain and its fibres

Answer 25

less localised and longer lasting via unmyelinated C fibres

Question 26

Describe discriminative pain

Answer 26

well localised and brief via A delta fibres (small myelinated fibres)

Question 27

which tract does the discriminative pathway follow?

Answer 27

anterolateral (neospinothalamic)

anterolateral tract –> thalamus (VPL) nucleus –> post central gyrus

Question 28

which tract does the affective pain pathway follow?

Answer 28

spinoreticular (paleospinothalamic)

bilateral –> reticular formation (brain stem) –> thalamus (intralaminar nucleus) –> also connnects to hypothalamus and amygdala (deep in temporal lobe) –> cingulate gyrus

Question 29

which cortical areas are involved in pain perception?

Answer 29

• post central gyrus (discriminitive)
• insula (both)
  cingulate gyrus (affective pain)

Question 30

what treats pain and reduces fMRI signals in insula and thalamus?

Answer 30

opioid

Question 31

in which tracts does the 2nd neuron cross in the spinal cord?

Answer 31

anterolateral (spinothalamic) tract

Question 32

in the dorsal column does the second neuron cross in the spinal cord?

Answer 32

nope

Question 33

a hemisection of the cord would result in?

Answer 33

loss of pain sensation on contralateral below lesion and loss of proprioception ipsilaterally below

Question 34

pathways to the cerebellum (ascending)

Answer 34

dorsal and ventral spinocerebellar tracts

2 neurons same side

Question 35

dorsal spinocerebellar tracts

unconscious proprioception muscle spindles/ tendon organs mainly from leg same side

Answer 35

from leg –> from arm clarkes nucleus (same side) –> lateral cuneate nucleus

inferior C. peduncle - same side - cerebellar entry

Question 36

ventral spinocerebellar tracts

Answer 36

also mainly concerned with leg input - movement

superior cerebellar peduncle