Auditory and Visual Pathways

cornea

primary refraction of light (no neural control)

f

*t/f* the cornea has neural control

choiroid

blood vessels, pigmented; layer between sclera and retina

lens

refracts light

t

*t/f* the lens has neural control

iris

controls the amount of light entering eye

ciliary

the _________ muscle changes the lens

lens

ciliary muscle changes the ________

retina

has photoreceptors

optic disc

blind spot

fovea

light focused here

macula lutea

area around the fovea

rods

black and white photoreceptors

cones

color photoreceptors

photoreceptors

these make up the first layer of the retina

bipolar

_______ cells make up the inner nucleus layer of the retina

ganglion

__________ cells make up the third layer of the retina

retina

the ________ has 3 key layers:

1. photoreceptors (rods & cones)

2. inner nucleus layer (bipolar cells)

3. ganglion cells

II

CN ___ is the optic nerve

optic

CN II is the ___________ nerve

sensory

optic nerve is *sensory/motor/both*

vision

function of CN II

retinal ganglion cells

cell bodies of optic nerve are ___________ ___________ ____________

thalamus

CN II projects to _________ → visual (occipital) cortex

occipital

CN II projects to thalamus → visual (___________) cortex

afferent

CN II = _________ limb of pupillary & consensual & accommodation reflexes

inverted

the image is ____________ on the retina & brain must reverse it

binocular

__________ zone: ~114° seen by both eyes

monocular

__________ zone: remaining visual field seen by only one eye

114

binocular zone is ~_____°

200-220

human visual field is ~____-____°

temporal

the nasal retina receives light from the ___________ visual field

nasal

the temporal retina receives light from the ________ visual field

left and right

objects in the left visual field enter into the *left/right/left and right* eye(s)

right

objects in the left visual field end in the *left/right/left and right* occipital lobe(s)

opposite

nasal visual field info goes to the temporal retina of the *same/opposite* eye

light

cells in the retina convert _________ into neural signals (rods and cones)

0

the bipolar cell in the retina is the ____° neuron of the visual pathway

bipolar

the _________ cell is the 0° neuron of the visual pathway

first

the ________ order neuron of the visual pathway is the ganglion cell
⇒axons make up the optic nerve
⇒some info crosses in optic chiasm, some stays ipsilateral
⇒optic tract
⇒project to lateral geniculate nucleus/body in thalamus

lateral geniculate

first order neuron of visual pathway: ganglion cell
⇒axons make up optic nerve
⇒some info crosses in optic chiasm
⇒optic tract
⇒project to __________ ___________ nucleus/body in thalamus

second

_________ order neuron of visual pathway
⇒cell body in lateral geniculate body in thalamus
⇒optic radiations/meyer's loop
⇒posterior limb of internal capsule
⇒primary visual cortex in occipital lobe

lateral geniculate

second order neuron of visual pathway cell body is in the ________ __________ body in the thalamus

second

the ________ order neuron of the visual pathway has optic radiations (meyer's loop) that project to primary visual cortex in occipital lobe

optic radiations

fibers from geniculate to primary visual cortex

meyer's loop

fibers from inferior half of retina (superior visual field) loop anteriorly around lateral ventricle

inferior

meyer's loop consists of fibers from the ______ half of the retina

superior

meyer's loop carries information from the ________ visual field

lateral ventricle

meyer's loop: fibers from inferior half of retina (superior visual field) loop anteriorly around _________ _________

superior

optic radiatons: fibers from the ________ half of the retina sweep around the ventricle

nasal

the ___________ hemi-retina crosses

temporal

the ___________ hemi-retina does not cross

temporal

the __________ visual field crosses

nasal

the ____________ visual field does not cross

visual field

clinically, visual loss is described by the *retinal/visual field* deficit

common

visual field deficits are *common/uncommon*

homonymous hemianopia

L/R ____________ ____________ - loss of vision to the L/R of midline respectively

bitemporal hemianopia

_____________ _____________ - loss of the temporal fields in both eyes; not common; ex: pituitary tumor

bitemporal hemianopsia

a pituitary tumor could cause ___________ _____________

uncommon

bitemporal hemianopsia is *common/uncommon*

uncommon

you can lose upper or lower, right or left quadrant in both eyes - this is *common/uncommon*

ipsilateral

a lesion to the optic nerve will cause *ipsilateral/contralateral/bilateral* eye blindness

temporal

a lesion of the optic chiasm will cause bilateral loss of the ________ visual fields

contralateral

a lesion to the optic tract will cause loss of the *ipsilateral/contralateral* hemifield from both eyes

quadrantanopia

upper left homonymous ______________ is caused by a lesion to right Meyer's loop

medial longitudinal fasciculus/MLF

longitudinal column to connect CN 3, 4, 6, 8, and 11
⇒synergistic action of extraocular muscles
⇒coordination of head & eye movements
⇒lesions can cause double vision among other deficits

3 4 6 8 11

MLF connects CN ___, ___, ___, ___, and ___

double vision

_________ __________ is a symptom of lesion of MLF

pretectum

visual reflexes involve midbrain ___________ and superior colliculus

superior colliculus

visual reflexes involve midbrain pretectum and ___________ ______________

80-90

____-____% of fibers go to occipital lobe

10-20

____-____% of fibers go to midbrain for visual reflexes

pretectum

the __________ coordinates pupillary reflexes

superior colliculus

the _________ ________ is responsible for visually guided eye movements

pupillary light

___________ ___________ reflex:
⇒CN II
⇒pretectal nucleus in midbrain
⇒parasympathetic nucleus of CN III (Edinger-Westphal)
⇒ciliary ganglion - pupillary sphincter muscle (constrict)
⇒consensual effect
⇒afferent vs. efferent

II

pupillary light reflex:
⇒CN ___
⇒pretectal nucleus in midbrain
⇒parasympathetic nucleus of CN III (Edinger-Westphal)
⇒ciliary ganglion - pupillary sphincter muscle (constrict)
⇒consensual effect
⇒afferent vs. efferent

pretectal nucleus

pupillary light reflex:
⇒CN II
⇒___________ _____________ in midbrain
⇒parasympathetic nucleus of CN III (Edinger-Westphal)
⇒ciliary ganglion - pupillary sphincter muscle (constrict)
⇒consensual effect
⇒afferent vs. efferent

Edinger-Westphal

pupillary light reflex:
⇒CN II
⇒pretectal nucleus in midbrain
⇒parasympathetic nucleus of CN III (__________-__________)
⇒ciliary ganglion - pupillary sphincter muscle (constrict)
⇒consensual effect
⇒afferent vs. efferent

ciliary

pupillary light reflex:
⇒CN II
⇒pretectal nucleus in midbrain
⇒parasympathetic nucleus of CN III (Edinger-Westphal)
⇒__________ ganglion - pupillary sphincter muscle (constrict)
⇒consensual effect
⇒afferent vs. efferent

consensual

pupillary light reflex:
⇒CN II
⇒pretectal nucleus in midbrain
⇒parasympathetic nucleus of CN III (Edinger-Westphal)
⇒ciliary ganglion - pupillary sphincter muscle (constrict)
⇒__________ effect (occurs bilaterally)
⇒afferent vs. efferent

efferent

light is directed in the L eye of the patient. this elicits a consensual response in the R eye, but not a direct one in the L eye (L pupil is fixed and dilated). the *afferent/efferent* limb of the pupillary reflex has been damaged

II

light is directed in the L eye of the patient. this elicits a consensual response in the R eye, but not a direct one in the L eye (L pupil is fixed and dilated). CN *II/III* is still intact

left

light is directed in the L eye of the patient. this elicits a consensual response in the R eye, but not a direct one in the L eye (L pupil is fixed and dilated).
if you shine a light in the right eye, there will be no response in the *right/left/both/neither* eye(s)

III

light is directed in the L eye of the patient. this elicits a consensual response in the R eye, but not a direct one in the L eye (L pupil is fixed and dilated). the lesion for this deficit is CN ____

near triad

adjustments of eyes to look at a near target

1. adjust lens - increased convexity (accommodation)

2. constrict pupil

3. convergence of eyes

increased

near triad: adjustments of eyes to look at a near target

1. adjust lens - increased/decreased convexity (accommodation)

2. constrict pupil

3. convergence of eyes

constrict

adjustments of eyes to look at a near target

1. adjust lens - increased convexity (accommodation)

2. dilate/constrict pupil

3. convergence of eyes

convergence

adjustments of eyes to look at a near target

1. adjust lens - increased convexity (accommodation)

2. constrict pupil

3. convergence/divergence of eyes

accommodation

___________ reflex:
⇒CN II to lateral geniculate
⇒occipital lobe
⇒midbrain - parasympathetic via CN III to constrict pupil and adjust lens for focus
⇒frontal eye field - efferent via CN III to medial rectus to move eyes

II

accommodation reflex:
⇒CN ___ to lateral geniculate
⇒occipital lobe
⇒midbrain - parasympathetic via CN III to constrict pupil and adjust lens for focus
⇒frontal eye field - efferent via CN III to medial rectus to move eyes

lateral geniculate

accommodation reflex:
⇒CN II to _______ ___________
⇒occipital lobe
⇒midbrain - parasympathetic via CN III to constrict pupil and adjust lens for focus
⇒frontal eye field - efferent via CN III to medial rectus to move eyes

III

accommodation reflex:
⇒CN II to lateral geniculate
⇒occipital lobe
⇒midbrain - parasympathetic via CN ____ to constrict pupil and adjust lens for focus
⇒frontal eye field - efferent via CN III to medial rectus to move eyes

medial rectus

accommodation reflex:
⇒CN II to lateral geniculate
⇒occipital lobe
⇒midbrain - parasympathetic via CN III to constrict pupil and adjust lens for focus
⇒frontal eye field - efferent via CN III to __________ _________ to move eyes

external

*external/middle/inner* ear: auricle/pinna

middle

*external/middle/inner* ear: air-filled pouch
⇒tympanic membrane
⇒3 bones/ossicles: malleus, incus, stapes

inner

*external/middle/inner* ear: fluid filled tubes
⇒cochlea
⇒3 chambers
⇒scala vestibuli
⇒scala media/cochlear duct
⇒scala tympani
⇒note: CN VIII (2 branches)

scala vestibuli

inner ear: fluid filled tubes
⇒cochlea
⇒3 chambers
⇒________ ________
⇒scala media/cochlear duct
⇒scala tympani
⇒note: CN VIII (2 branches)

scala media

inner ear: fluid filled tubes
⇒cochlea
⇒3 chambers
⇒scala vestibuli
⇒_________ _________/cochlear duct
⇒scala tympani
⇒note: CN VIII (2 branches)

scala tympani

inner ear: fluid filled tubes
⇒cochlea
⇒3 chambers
⇒scala vestibuli
⇒scala media/cochlear duct
⇒________ ________
⇒note: CN VIII (2 branches)

basilar membrane

the ________ _______ of the inner ear separates the scala vestibuli and scala media from the scala tympani