10: Anatomy - Auditory, vestibular and visual pathways Flashcards
Which cranial nerve is responsible for hearing?
Cochlear part of CN VIII
Which specialised cells are responsible for picking up vibrations in the inner ear?
Where exactly are they found?
Hair cells
Scala media in the Organ of Corti
Which type of nerve fibre is closely related to hair cells in the cochlea and converts vibrations to action potentials?
Special sensory fibres of CN VIII
Where do special sensory fibres of the inner ear synapse before travelling to the brain?
Spiral ganglia
In which two parts of the brainstem do the special sensory neurons of CN VIII synapse?
Cochlear nuclei in the PONS
Inferior colliculus in the MIDBRAIN
Which nerve bodies do special sensory fibres from the ear synapse at in the
a) inner ear
b) pons
c) midbrain
before passing to the auditory cortex of the brain?
a) Spiral ganglion
b) Cochlear nucleus
c) Inferior colliculus
In which lobe is the primary auditory cortex found?
Temporal lobe
At which point do fibres from the auditory pathway decussate?
After the cochlear nucleus
Do all auditory pathway fibres cross over after the cochlear nucleus?
No
So after this the pathway is bilateral
After the cochlear nucleus, the auditory pathway for each side of the brain contains fibres from the (ipsilateral / contralateral) side.
both
so the pathway is bilateral; info from both ears is processed on both sides
What does tonotopy mean in relation to the auditory pathway?
Different frequencies of sound are processed by different parts of the primary auditory cortex
What named area is found in the primary auditory cortex?
Wernicke’s area
What named area is found in the posterior frontal lobe?
Broca’s area
Which named area of the brain is damaged to cause difficulty comprehending language?
Wernicke’s area of the primary auditory cortex
What is difficulty comprehending language called?
Wernicke’s aphasia
Which named area is damaged to cause a difficulting producing language?
Broca’s area in the posterior frontal lobe
What is difficulty producing language called?
Broca’s aphasia
What is difficulty
a) producing
b) comprehending
language called?
Which areas of the brain are damaged to cause these diseases?
a) Broca’s aphasia - posterior frontal lobe
b) Wernicke’s aphasia - primary auditory cortex (temporal lobe)
Which cranial nerve is responsible for balance?
Vestibular part of CN VIII
Which cranial nerve is responsible for vision?
CN II - Optic nerve
What is unusual about the nerve arrangement of the retina?
Light needs to pass through all the ganglia and axons to reach photoreceptors
What are the two types of photoreceptor found in the eye?
Rods
Cones
Which type of light is picked up by rods?
Black and white; low light
High acuity - so subtle movements but not in much detail
Which type of light is picked up by cones?
Colour
Low acuity
Which side of the brain is information from the right visual field processed on?
Left
Which side of the brain is information from the left visual field processed on?
Right side
At which structures in the visual pathway do nerve fibres
a) cross over
b) synapse?
a) Optic chiasm
b) Lateral geniculate nucleus
Where does the first synapse in the visual pathway occur?
Lateral geniculate nucleus
What are the paired structures, found in the midbrain, which are involved in vision and hearing?
Which is involved in each sense?
Superior and inferior colliculi
Vision - superior colliculus
Hearing - inferior colliculus
What is the end-point of the visual pathway?
Where in the brain is it found?
Visual cortex
Posterior occipital lobe
Which feature of the occipital lobe is the visual cortex found around?
Calcarine sulcus
Where in the brain is the
a) visual cortex
b) auditory cortex found?
a) Posterior occipital lobe
b) Temporal lobe
Which areas of the visual cortex process
a) the superior visual field
b) the inferior visual field?
a) INFERIOR visual cortex (below the calcarine sulcus)
b) SUPERIOR visual cortex (above the calcarine sulcus)
Which visual fields are processed by the
a) visual cortex ABOVE the calcarine sulcus
b) visual cortex BELOW the calcarine sulcus?
a) Inferior visual field
b) Superior visual field
Where does information from the macula get processed?
Posterior pole of the visual cortex
same arrangement re: superior and inferior
Which areas of the brain are involved in
a) hearing
b) balance
c) vision?
a) Primary auditory cortex - temporal lobe
b) Loads of areas, doesn’t seem that important
c) Primary visual cortex - occipital lobe
In terms of the visual pathway, what is Meyer’s loop?
Which structure of the brain does it go around?
The part of the tract processing UPPER VISUAL FIELD info, running from the lateral geniculate nucleus to the visual cortex
Lateral ventricle
What is the clinical significance of Meyer’s loop?
Because of its weird course, it can be damaged in surgery
e.g temporal lobe surgery re: epilepsy
What visual field defect will a patient get if Meyer’s loop is damaged?
“Pie in the sky” defect
A superior homonymous quadrantanopia, because it processes superior visual field info on the contralateral side for both eyes
Which nucleus is for pre-synaptic parasympathetic fibres from CN III and is involved in the pupillary light reflex?
Edinger-Westphal nucleus
Is the pupillary light reflex unilateral or bilateral?
bilateral
If a visual pathway lesion involves the visual cortex (i.e occurs towards the end of the pathway), what will be seen in the visual field defect?
Macular sparing
What specific parts of the brain are responsible for
a) most motor stuff
b) most sensory stuff
c) processing of motor and sensory signals before sending them to the cerebrum
d) alteration of motor signals to fit reality
e) hearing
f) vision?
a) Motor - pre-central gyrus of frontal lobe
b) Sensory - post-central gyrus of occipital lobes
c) Processing/Relay - thalamus
d) Alteration - cerebellum
e) Hearing - primary auditory cortex; temporal lobes
f) Vision - primary visual cortexl occipital lobe
