Visual and Auditory Pathways

Question 1

outermost layer of the eye

Answer 1

cornea and sclera
for protection, refraction and transmitting of light

Question 2

middle layer of the eye

Answer 2

vascular layer
choroid, ciliary body, iris

Question 3

what connects ciliary body to the lens

Answer 3

suspensory ligament

Question 4

what happens to the lens when ciliary body contracts

Answer 4

fattens and light is more focused

Question 5

secretion and absorption of aqueous humour

blocking of reabsorption

Answer 5

ciliary body secretes and reabsorbed by scleral venous sinus or canal of Schlemm

blockage leads to glaucoma (pressure on retina) -> blindness if untreated

Question 6

muscles of the iris

Answer 6

circularly arranged sphincter pupillae and radially arranged dilator pupillae

Question 7

role of choroid

Answer 7

supplies nutrients to the retina

when retina detaches it lacks nutrients and oxygen

Question 8

inner most layer of the eye

Answer 8

neural layer - retina

Question 9

layers of the retina

Answer 9

rods and cones (furthest from light path)
bipolar cells

Question 10

pathway of signals from rods and cones

Answer 10

[] rods and cones - bipolar cells
retinal ganglion cells - lateral geniculate nucleus - primary visual cortex

Question 11

axons of which cells form the optic nerve

Answer 11

retinal ganglion cells

Question 12

continuation of optic nerve

Answer 12

continues as optic chiasma - optic tract - lateral geniculate nucleus …

Question 13

axons from nasal and temporal hemiretinas at the optic chiasma

Answer 13

axons from nasal cross the midline
axons from temporal do not cross

Question 14

result of some axons from retina crossing the midline at the optic chiasm

Answer 14

the left visual field of both eyes is represented on the right visual cortex
and vice versa

Question 15

primary visual cortex

Answer 15

where axons from lateral geniculate nucleus terminate in the occipital lobe

Question 16

two streams of visual processing from the primary visual cortex

Answer 16

‘what’ stream to temporal lobe
‘where’ stream to parietal lobe

Question 17

where do axons that mediate the afferent part of pupillary light reflex terminate

what mediates the efferent part

Answer 17

Edinger Westphal nucleus

parasympathetic fibres in the oculomotor nerve (to intrinsic and extrinsic muscles of the eye)

Question 18

route of oculomotor nerve

Answer 18

given off from the midbrain
passes along lateral wall of cavernous sinus and enters the orbit

Question 19

motor supply by oculomotor nerve

Answer 19

most of the extraocular muscles that move the eyeball and intrinsic muscles of the eye (including eyelid)

Question 20

fibres of oculomotor nerve

where do they synapse

Answer 20

preganglionic parasympathetic fibres from cell bodies in EW nucleus

ciliary ganglion

Question 21

lesion of oculomotor nerve

Answer 21

paralysis of many extraocular muscles
diplopia
loss of light response
loss of accommodation

Question 22

route of trochlear nerve

Answer 22

only cranial nerve to emerge from dorsal aspect of brainstem
passes along lateral wall of cavernous sinus and enters orbit

Question 23

motor supply of trochlear nerve

Answer 23

one of the extraocular eye muscles

Question 24

lesion of trochlear nerve

Answer 24

causes paralysis of one of the extraocular muscles
diplopia

Question 25

route of abducens nerve

Answer 25

leaves brain at pontomedullary junction runs across sharp edge of petrous temporal bone passes through cavernous sinus and enters orbit

Question 26

motor supply of abducens nerve

Answer 26

one of the extraocular eye muscles

Question 27

lesion of abducens nerve

Answer 27

paralysis of one of the extraocular muscles diplopia patients presents with medial deviation of affected eye may result from sepsis or thrombosis in cavernous sinus

Question 28

cochlea role

Answer 28

part of the inner ear organ of hearing

Question 29

role of semicircular canals

Answer 29

sense head position and rotation

Question 30

embedding of inner ear

Answer 30

dense structure of temporal bone dense enough to conduct sound via bone as well as the sound that comes via ear canal

Question 31

interior of cochlea

Answer 31

three fluid filled tubes uppermost is the scala vestibule scala media is between lowermost compartment is scala tympani basilar membrane partition between media and tympani

Question 32

role of basilar membrane in cochlea

Answer 32

mechanical analyser of sound frequency physical properties are not uniform, tighter regions resonate with higher pitch, distal (more floppy) resonate with lower pitch

Question 33

basilar membrane mechanical properties along its length

Answer 33

5x broader at apex (base of cochlea) thicker and tauter toward the base

Question 34

organ of Corti

Answer 34

receptor organ of the inner ear

Question 35

vestibulocochlear nerve route

Answer 35

leaves pontomedullary junction enters internal acoustic meatus together with facial nerve

Question 36

sensory supply of vestibulocochlear nerve

Answer 36

sensory cells of the inner ear

Question 37

cochlear portion and vestibular portion of vestibulocochlear nerve

Answer 37

cochlear portion derives from bipolar neurons in spiral ganglion innervate hair cells of cochlea vestibular portion arises from bipolar neurons in vestibular ganglion innervate sensory cells of semicircular canals as well as saccule

Question 38

lesion of vestibulocochlear nerve

Answer 38

loss of hearing or vestibular sense vertigo tinnitus

Question 39

cochlear nucleus

Answer 39

cochlear nerve sends branches to dorsal and ventral cochlear nuclei

Question 40

superior olivary nucleus input how does it localise sound

Answer 40

receives input from each cochlear nucleus medial portion compares time of arrival of signal at each ear lateral portion compares sound intensities

Question 41

inferior colliculus input and projections what is it responsible for

Answer 41

receives input from cochlear nucleus / superior olivary nucleus projects to medial geniculate nucleus of the thalamus responsible for reflex orienting to auditory stimuli

Question 42

medial geniculate nucleus role and projections

Answer 42

thalamic relay nucleus projects to ipsilateral primary auditory cortex

Question 43

primary auditory cortex location and role effect of stimulation and damage

Answer 43

superior aspect of temporal lobe receives primary auditory information from both ears stimulation leads to tinnitus and damage leads to slight hearing loss of affected side

Question 44

auditory association cortex location and role

Answer 44

superior temporal gyrus left side is essential for understanding speech