NBSS: (neuroscience) - Ascending & descending pathways Flashcards
how many spinal nerves are there?
31
how are the 31 nerves in the spinal cord separated?
8 cervical
12 thoracic
5 lumbar
5 sacaral
1 coccygeal
which one is shorter, the spinal cord or the vertebral column?
spinal cord is shorter than vertebral column (normally ends between lumbar vertebral 1/2)
where is the lumbar puncture?
between lumbar vertebrae 3 and 4 - no spinal cord here
in the spinal cord, where is the white and grey matter found?
grey matter INSIDE
white matter OUTSIDE
sesnsory receptors enter the spinal cord via the …
dorsal root
motor neurones exit via the
ventral root
what is used to stain the spinal cord in photographs?
weigert-pal
what does weigert-pal stain?
it stains myelin which is the white matter therefore turning it black in photographs
what is one example of a reflex that the spinal cord is involved in?
patellar tendon (knee jerk) reflex
what are 2 types of pathways in the spinal cord
ascending and descending
what are 2 types of ascending and descending pathways
ascending pathway:
- general somatic afferents (GSAs)
- general visceral afferents (GVAs)
descending pathway:
- general somatic efferents (GSEs)
- general visceral efferents (GVEs)
somatic = CONCIOUS
visceral = SUBCONCIOUS
what are the 3 sensory pathways
spinothalamic tract
dorsal column medial lemniscus
spinocerebellar tract
what is the spinothalamic tract responsibsle for? describe it
responsible for pain and temperature
- 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
- makes a connection to the 3rd order neurone in the thalamus, sending info to the somatosensory coretex
what is the dorsal column medial lemniscus pathway responsible for? describe what happens in this pathway
responsible for fine touch/ 2 point discrimination/ vibration/ concious proprioception
- sensory receptors enter spinal cord via dorsal horn going straight up to medulla oblongata
- then it dessuctates and project to the thalamus, synpasing to 3rd order neurone and synapses to somatosensory cortex
the spinocerebellar tracts are responsible for what? describe this pathway
responsible for subconcious proprioception
- sensroy neurons enter via dorsal root and synapses to 2nd order neurone in dorsal horn
- 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
- cerebellum sends info via thalamus to the motor cortex
which sense is not processed in the thalamus
olfactory (smell)
what are the 5 types of descending pathways
corticospinal tract
reticulospinal tract
rubrospinal tract
tectospinal tract
vestibulospinal tracts
what is the corticospinal tract responsible for? describe this pathway
voluntary control of skilled movements
what is the reticulospinal tract responsibsle for?
posture and locomotion
what is the vestibulospinal tract responsible for?
balance, posture, ‘anitgravity’
what is the rubrospinal tract responsible for
facilitation of flexion
what is the tectospinal tract responsible for
coordination of head and eye movements
where do all descending tracts originate from, what is the exception to this?
all descending tracts originate from brain stem EXCEPT corticospinal tract which originates from cortex
difference between where dorsal, spinothalamic and corticospinal tract decussate
dorsal/ corticospinal = medulla oblongata
spinothalamic = spinal cord
