Neuroanatomy Exam 2 - Visual system

what are the 3 layers of the eye

sclera

choroid

retina

what does the sclera include

cornea

what does the choroid include

iris

what does the retina include

photoreceptor cells

what are the 3 chambers of the eye

anterior

posterior

vitreous body

light is refracted (bent) as it travels through the ______; because of this the visual fields onto the_______ is reversed and inverted

cornea; retina

__________-area of environment that is perceived by each eye

visual field

extensive, posterior region

choroid

_______ make melanin to absorb extraneous light

melanocytes

what nourishes the retina

capillaries

_______ contains ciliary muscles and processes

ciliary body

what does the middle layer of the eye include

choroid and ciliary body

what does the iris include

pupil and iris

this is the opening in the center of iris connecting the two chambers

pupil

This divides the anterior segment into the anterior and posterior chambers

iris

what controls the pupil diameter

iris

these are circular fibers that constrict the pupil with parasympathetic nervous system activity (CN III)

sphincter pupillae muscles

these are smooth muscle dilates pupil with sympathetic nervous system activity

dilator pupillae muscles

these alters pupil size in response to light

pupillary reflex

accommodation, controlled by autonomic motor neurons of the peripheral nervous system found within the

oculomotor nerve (CN III)

for objects how far?

1. eyes face forward

2. lens is flattened

3. pupil is relatively dilated to allow greater amount of light into the eye

20 feet away and further

for objects how far?

1. extrinsic muscles pull eyes medially

2. cillary muscles contraction thickens lens

3. spincter pupilae contraction shrinks hole

closer than 20 feet

emmetropia is

normal vision

hyperopia is

farsightedness (near objects are blurry)

myopia is

nearsightedness (far objects are blurry)

_____ lens causes greater focus of light rays

convex

________ lens causes greater divergence of light rays

concave

what are the two layers of the retina

-pigmented

-neural

this layer attaches to the choroid and absorbs stray light to prevent light scatter

pigmented

this layer houses photoreceptors and associated neurons and receives light and converts it to the nerve signals

neural layer

what are the 3 sublayers of the neural layer

-photoreceptors

-bipolar

-ganglion

this cell layer is the outermost nerual layer, contains rods and cones and pigments that react to light

photoreceptor

this cell layer has dendrites receive synaptic input from rods and cones

bipolar

this cell layer is the innermost neural layer and their axons gather at optic disc and from optic nerve; capable of action potentials

ganglion

these allows us to see in dim light and detect movement

rods

these specialized for color vision

cones

color vison deficiency (CVD) is also known as

color blindness

the area of highest visual acuity in daylight conditions, contains only cones

fovea

optic disc

“the blind spot”

circular area near edge of optic disc

macula lutea

pathway for vision

1. The contralateral visual field projects onto the temporal or lateral portion of the retina

2. the optic nerve carries all information from the ipsilateral eye

3. nasal retinal fibers cross in the optic chiasm

4. the optic tract contains fibers from the contralateral visual field

5. the optic radiations are the projections from the lateral geniculate body to the primary visual cortex

where do the nasal reinal fields cross over

optic chiasm

after the nasal retinal fields cross over, optic tract now contains fibers from which visual field

whole contralateral visual field

optic tract synapses in the ____________ of the thalamus for processing

lateral geniculate nucleus

the right optic nerve

-temporal half of left visual field

-nasal half of right visual field

the left optic nerve

-nasal half of left visual field

-temporal half of right visual field

right optic tracts:

left visual field of nasal and temporal

left optic tracts

right visual field of nasal and temporal

coordination of eye, head, and neck movements for visual tracking; visual reflexes

superior colliculi

primary visual cortex

banks of calcarine sulcus

-right cerebral hemisphere receives information from the left visual field and vise versa

anposia

loss of vision in one of both eyes

hemianopsia

loss of vision in half of a visual field in each eye

homonymous

same visual field in each eye

quadrantopia

loss of quadrant of a visual field

macular sparing

phenomenon associated with lesion in the visual cortex

anopsia is damage to

the optic nerve

the function of this muscle is intorsion - rotates the top of the eye inward (toward the nose) and depression - helps move the eye downward

superior oblique

the function of this muscle is extorsion - rotates the top of the eye outward (away from the nose) and elevation - helps move the eye upward

inferior oblique

LR^ SO4, all the rest are 3

lateral rectus CN VI (abducens)

superior oblique IV (trochlear)

inferior oblique and the rest CN III (oculomotor)

superior, middle, inferior rectus, inferior oblique, levator palpebrae superioris are

general somatic efferent

constrictor pupillae and ciliary muscles are

general visceral efferent

the nuclei of this nerve is midline in the midbrain just anterior to cerebral aquduct

oculomotor

the smallest cranial nerve and only one that crosses before exisiting the brainstem

trochlear

this nerve is more inferior in midbrain at level of inferior colliculus

trochlear

this nerve innervates lateral rectus muscle and is the only somatic motor fibers

abducens nerve

fiber tract that innerconnects the CN II, IV, and VI to each other and the vestibular nuclei

medial longitudinal fasciculus

the ________ MLF connects the abducens nucleus to the oculomotor nucleus and the vestibular nuclei

ascending

the ____________ MLF is the medial vestibulospinal tract

descending

what rapidly adjusts eye movements to head movements so that gaze can remain fixed when head is moving

vestibular ocular reflex

what is a vision condition characterized by involuntary, rhythmic, and repetitive eye movements

nystagmus

the H-test tests for which cranial nerves

II, IV, and VI

what is the purpose of the H-test

assessing eye movements

lesion is the right optic nerve effects

complete blindness in that eye (anopsia)

lesion is the right optic nerve effects

complete blindness

lesion is the optic chiasm effects

lose temporal visual fields; bitemporal hemianopia

lesion is the right optic tract effects

lose both left visual fields; left/contralateral homonymous

lesion is the left optic nerve effects

lose both right visual fields; right contralateral homonymous

lesion is the right optic radiation in parietal lobe effects

lose inferior portion of both left visual fields; inferior left homonymous quadrantopia

lesion is the left optic radiation in parietal lobe effects

lose inferior portion of both right visual fields; inferior right homonymous quadrantopia

lesion is the right optic radiation in temporal lobe effects

lose superior portion of both left visual fields; superior left homonymous quadrantopia

lesion is the left optic radiation in temporal lobe effects

lose superior portion of both right visual fields; superior right homonymous quadrantopia

lesion is the right visual cortex effects

lose both left visual fields but macula typically spared

lesion is the left visual cortex effects

lose both right visual fields but macula typically spared