special senses

what comprises the outer fibrous layer of the eye?

the sclera, the cornea, and the aqueous humor

what is the function of the sclera

helps keep the eye anchored inside of skull

what is the structure of the sclera?

on the posterior portion of the eye, also known as the white of the eye

what is the structure of the cornea

on the anterior portion of the eye, transparent

what is the function of the cornea?

light enters through the cornea

what is the structure of the aqueous humor?

fills the space between the cornea and the lens

what comprises the middle layer of the eye?

choroid, ciliary body, iris, pupil, lens

what is the structure of the choroid

wraps around to the posterior portion of the eye, darkly colored, highly vascular

what is the function of the choroid?

supplies blood to the eye

what is the structure of the ciliary body?

on anterior surface of the eye, attaches to lens

what is the function of the ciliary body?

allows shape of lens to change, allows for focus

what is the structure of the iris?

colored part of the eye!

what is the function of the iris?

controls the amount of light that enters the pupil, contracts and dilates based on environmental light

what is the structure of the lens?

posterior to the iris and pupil, ciliary body attaches all around lens

what comprises the inner sensory layer?

the retina!

what is the structure of the retina?

on the posterior of the eye, directly behind ciliary body. contains photoreceptors called rods and cones.

what is the function of the retina?

contains rods and cones that allow for images to be seen!

what is the function of a rod?

sensitive to dim light, does not generate sharp or color images

what is the function of a cone?

operate in bright light, help detect color images

what is the structure of the vitreous body?

deep to the retina, posterior to the lens. chamber filled with vitreous fluid

what is the function of the vitreous body?

hold retina firm and flush to the choroid

what is the nasal visual field?

overlapping left and right visual fields closest to the nose that allows for 3d vision

what is the peripheral visual field?

the lateral side of each eye

what is the left visual field?

the left side of the visual field from each individual eye, interpreted by the right side of the brain

what is the right visual field?

the right side of the visual field from each individual eye, interpreted by the left side of the brain

what would damage to the right occipital lobe result in?

visual impairment of left visual fields of both eyes!

what would damage to the right optic nerve result in?

damage to both visual fields of the right eye

what is the visual pathway, from environment to brain?

cornea, posterior surface of retina, photoreceptors detect light, optic nerve, optic chiasm, optic tracts, LGN, optic radiations, occipital lobe!

what is the function of the medial rectus?

turns eye medially

what nerve innervates the medial rectus?

CN III (oculomotor nerve)

medial rectus

what is the function of the inferior rectus?

depresses eye, moves eye medially

what nerve innervates the inferior rectus?

CN III (oculomotor nerve)

inferior rectus

what is the function of the superior rectus?

elevates eye, moves eye medially

what nerve innervates the superior rectus?

CN III (oculomotor nerve)

superior rectus

what is the function of the superior oblique?

internal rotation, depresses eye, moves eye laterally

what nerve innervates the superior oblique?

CN IV (trochlear nerve)

superior oblique

what is the function of the inferior oblique?

elevates eye, moves eye laterally, external rotation

inferior oblique

what is the function of the lateral rectus?

turns eye laterally

what nerve innervates the lateral rectus?

CN VI (abducens nerve)

what nerve innervates the inferior oblique?

CN III (oculomotor nerve)

What is cataracts?

lenses slowly harden and become cloudy over time. vision is blurry

what is an example of abducens nerve damage?

double vision!

what is diplopia?

double vision

true or false: if a patient’s abducens nerve is damaged, the eye will be able to rotate laterally

false!

what is the function of the external ear?

to funnel sound waves into the ear

what is the structure of the external ear?

composed of elastic cartilage and covered with skin

what is unique about the lobule on the external ear?

lacks cartilage

what is the structure of the external acoustic meatus?

tunnel between auricle and the tympanic membrane, lined with hairs and ear wax

what is the structure of the tympanic membrane?

thin membrane of connective tissue, ear canal terminates here

what is the function of the tympanic membrane?

transmits sound energy to the middle ear

what is the structure of the middle ear?

air filled chamber with three bones

what is the function of the middle ear?

the malleus receives vibration from the tympanic membrane and conducts them to the inner ear

what is the structure of the inner ear?

two fluid filled labyrinths, one bony and one membranous

what does the bony labyrinth contain?

the cochlea, and the membranous labyrinths

what does the membranous labyrinth contain

the utricle and saccule, tiny bones that help with balance

what cranial nerve is found in the inner ear?

CN VII, facial nerve

what is the function of the facial nerve in the inner ear?

innervates stepedius, controls intensity of sounds

what is the structure of the vestibular system

three fluid filled semicircular canals

what is the function of the vestibular system

fluid filled canals have equilibrium receptors that have action potentials in response to different head rotations or movements

what is the structure of the cochlea?

spiral bony chamber, houses organ of corti, ends at the cochlear nerve

what is the structure of the organ of corti?

contains a tectorial membrane, which stereocilia attach to, vibrations move the stereocilia, which initiates an action potential which is carried through the cochlear portin of CN VIII

what are the steps of the hearing pathway?

cochlear nerve, primary auditory cortex of the temporal lobe

true or false → sound pathways cross to opposite side of the brain only

false! sound is duplicated and send to the left and right sides of the brain

what is conduction deafness?

damage to outer or middle ears, which causes partial deafness

what is nerve deafness?

damage to the nervous pathway, can be partial or complete