Neuroanatomy 5 Flashcards

1
Q

how many turns in the cochlea?

A

2.5 turn spiral

3 tubes turning together

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2
Q

where is the organ of corti?

A
long ribbon of tissue between scala media and scala tympani on top of the basilar membrane
function = receptor for hearing includes inner and outer hair cells
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3
Q

organization of the cochlea?

A

tonotopically organised
base = high pitched sounds
tip = low pitched sounds

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4
Q

how sound travel to brain?

A

tectorial membrane vibrates on the stereocilia (hair cells) of the organ of corti which create APs which travel through the spiral ganglion where bipolar neurons are stimulated and carry the AP from organ of corti to the cochlear nuclei in the pons via vestibulocochlear nerve

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5
Q

how do sound signals travel?

A

synapse at dorsal and ventral cochlear nuclei either side of the inferior cerebellar peduncle
superior to the nuclei, some fibres are crossed and some are not, therefore input above the level of the nuclei is bilateral
2nd order neurons then travel and synapse on the superior olivary nucleus
3rd order neurons travel and synapse on the inferior colliculus
4th order neurons travel and synapse at the thalamus at the medial geniculate body
5th order neurons then travel to specific area of the brain

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6
Q

how is sound localised?

A

to do with timing of perception of sound - difference in time taken for sound to reach right vs left ear
superior olivary nucleus and nucleus of lateral lemniscus (band of white matter carrying auditory information up the brainstem) are involved

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7
Q

where are auditory areas of the brain found?

A

upper, posterior part of temporal lobe
- just underneath lateral fissure
primary auditory complex = most superior
auditory association cortex (surrounds primary and extends backwards)

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8
Q

how is the primary auditory cortex organized?

A

tonotopically
high frequencies = more posteromedial
low frequencies = more anterolateral

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9
Q

what is aphasia?

A

inability to use language

  • cant interpret incoming language (Wernicke’s/sensory/receptive aphasia - damage to Wernicke’s area)
  • cant generate outgoing language (motor/expressive aphasia - due to damage in brocas area)
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10
Q

association areas?

A

present adjacent to primary cortex areas

  • important for making sense of incoming information
  • larger than primary areas
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11
Q

maintenance of equilibrium (balance) uses information from where?

A

vision
proprioception
vestibular apparatus (labyrinth)

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12
Q

course of vestibular signalling?

A

signals to vestibular ganglion
cell bodies then project into the brainstem and synapse on vestibular nuclei
cell axons then project upwards to nuclei of oculomotor, trochlear and abducens nerves, thalamus, cerebellum and spinal cord

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13
Q

where in the brain does vestibular information converge?

A

posterior to the area of postcentral gyrus representing hand and mouth
area rostral to primary auditory complex
posterior insular cortex

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14
Q

layers of retina?

A
ganglions
amacrine cells
bipolar cells
horizontal cells
mullers cells
rods
cones
lamina vitrea
choroid
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15
Q

how does light travel through the retina?

A

goes all the way through the layers to the photoreceptive cells (rods and cones) at the back
then travels back up (being partly processed by some cells on the way up) back to the ganglion
fibres of the ganglia converge to form the optic nerve and travel to the brain

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16
Q

path of optic nerve?

A

optic tract > optic chiasm > lateral geniculate nucleus (bump on the back of the thalamus) > project back to the occipital lobe either side of the calcarine sulcus (this section called optic radiation)

17
Q

the optic tracts carry visual information from which visual fields?

A

right optic tract = left visual field
left optic tract = right visual field
this revered visual field representation persists until the visual cortex

18
Q

where else is visual information projected to?

A

superior colliculi

  • for aiming the eyes, reflexes etc
  • therefore people can be visually blind but still aim eyes correctly and maintain eye reflexes if these fibres are still intact
19
Q

where are the visual areas of the brain?

A

primary visual cortex = over calcarine sulcus at very back centre of occipital lobe
visual association cortex either side of this

20
Q

describe organisation between the macula and the visual cortex?

A

visual information received by the macula is projected to the posterior pole of the visual cortex and occupies a huge amount of space in the cortex relative to the size of the visual field perceived by the macula
this gives great acuity in centre of visual field

21
Q

what is Meyers loop?

A

fibres containing information from upper visual field (lower retina) has to take a large detour round the lateral ventricle on the way to the visual cortex

22
Q

types of eye movements?

A

tracking movements - controlled by the visual cortex, much smoother
movements of command - from frontal eye fields (motor cortex), jumpy movements

23
Q

describe the pupillary light reflex?

A

light activates optic nerve which synapses at the Edinger Westphal nucleus
oculomotor nerve travels from nucleus and synapses at ciliary ganglion which constricts pupillary constrictor muscle of iris
pupillary constriction is parasympathetic

24
Q

visual fields defects?

A
optic nerve = complete blindness in one eye
optic chiasm = bitemporal hemianopia
optic tract = homonymous hemianopia
optic radiation = homonymous hemianopia
occipital cortex = macular sparing,
25
Q

where is the primary gustatory area?

A

sits just above the lateral fissure

26
Q

what are the 3 types of fibres in white matter of the cerebral hemispheres?

A

association fibres - connect cortical sites in same hemispheres
commissural fibres - connect one hemisphere to other
projection fibres - connect hemispheres to deeper structures including thalamus, corpus striatum, brainstem and spinal cord