NBSS: (neuroscience) - Ascending & descending pathways

Question 1

how many spinal nerves are there?

Answer 1

31

Question 2

how are the 31 nerves in the spinal cord separated?

Answer 2

8 cervical
12 thoracic
5 lumbar
5 sacaral
1 coccygeal

Question 3

which one is shorter, the spinal cord or the vertebral column?

Answer 3

spinal cord is shorter than vertebral column (normally ends between lumbar vertebral 1/2)

Question 4

where is the lumbar puncture?

Answer 4

between lumbar vertebrae 3 and 4 - no spinal cord here

Question 5

in the spinal cord, where is the white and grey matter found?

Answer 5

grey matter INSIDE
white matter OUTSIDE

Question 5

sesnsory receptors enter the spinal cord via the …

Answer 5

dorsal root

Question 6

motor neurones exit via the

Answer 6

ventral root

Question 6

what is used to stain the spinal cord in photographs?

Answer 6

weigert-pal

Question 7

what does weigert-pal stain?

Answer 7

it stains myelin which is the white matter therefore turning it black in photographs

Question 8

what is one example of a reflex that the spinal cord is involved in?

Answer 8

patellar tendon (knee jerk) reflex

Question 9

what are 2 types of pathways in the spinal cord

Answer 9

ascending and descending

Question 10

what are 2 types of ascending and descending pathways

Answer 10

ascending pathway:
- general somatic afferents (GSAs)
- general visceral afferents (GVAs)

descending pathway:
- general somatic efferents (GSEs)
- general visceral efferents (GVEs)

somatic = CONCIOUS
visceral = SUBCONCIOUS

Question 11

what are the 3 sensory pathways

Answer 11

spinothalamic tract

dorsal column medial lemniscus

spinocerebellar tract

Question 12

what is the spinothalamic tract responsibsle for? describe it

Answer 12

responsible for pain and temperature

1. sensory neurone enters spinal cord and synpases to second order neurone in dorsal horn in the grey matter, this dessuctates (crosses over) to other side
2. makes a connection to the 3rd order neurone in the thalamus, sending info to the somatosensory coretex

Question 13

what is the dorsal column medial lemniscus pathway responsible for? describe what happens in this pathway

Answer 13

responsible for fine touch/ 2 point discrimination/ vibration/ concious proprioception

1. sensory receptors enter spinal cord via dorsal horn going straight up to medulla oblongata
2. then it dessuctates and project to the thalamus, synpasing to 3rd order neurone and synapses to somatosensory cortex

Question 14

the spinocerebellar tracts are responsible for what? describe this pathway

Answer 14

responsible for subconcious proprioception

1. sensroy neurons enter via dorsal root and synapses to 2nd order neurone in dorsal horn
2. can take 2 routes: it projects ipsilaterally (stays on same side) to the cerebellum, or can dessuctate along the midbrain and pons, and dessuctate again to cerebellum
3. cerebellum sends info via thalamus to the motor cortex

Question 15

which sense is not processed in the thalamus

Answer 15

olfactory (smell)

Question 16

what are the 5 types of descending pathways

Answer 16

corticospinal tract

reticulospinal tract

rubrospinal tract

tectospinal tract

vestibulospinal tracts

Question 17

what is the corticospinal tract responsible for? describe this pathway

Answer 17

voluntary control of skilled movements

Question 18

what is the reticulospinal tract responsibsle for?

Answer 18

posture and locomotion

Question 19

what is the vestibulospinal tract responsible for?

Answer 19

balance, posture, ‘anitgravity’

Question 20

what is the rubrospinal tract responsible for

Answer 20

facilitation of flexion

Question 21

what is the tectospinal tract responsible for

Answer 21

coordination of head and eye movements

Question 22

where do all descending tracts originate from, what is the exception to this?

Answer 22

all descending tracts originate from brain stem EXCEPT corticospinal tract which originates from cortex

Question 23

difference between where dorsal, spinothalamic and corticospinal tract decussate

Answer 23

dorsal/ corticospinal = medulla oblongata

spinothalamic = spinal cord