Lab 13 The Eye and Ear

Eyebrows

shade eyes and deflect dripping sweat

Palpebrae

distributes tears and blocks intense light

Conjunctiva

covers white of eye and lines the eyelid

Lacrimal Apparatus

lacrimal glands and group of ducts that produces tears

Sclera

White of the eye made of dense fibrous ct and is pierced posteriorly by optic nerve

Cornea

window which focuses light, made of clear dense fibrous ct and epithelia on the surfaces, richly supplied with pain receptors

Choroid

posterior uvea, absorbs light rays and nourished retina, pierced posteriorly by optic nerve

Ciliary processes

secrete aqueous humor

Ciliary muscles

alters the shape of lens

Suspensory ligaments

hold lens in place

Iris

colored ring and controls the flow of light to posterior eye

pupil

central opening of eye

Photoreceptors

rods and cones

Optic disc

blind spot

Macula Lutea

the “yellow spot”

Fovea Centralis

highest concentration of cones

Optic vessels

central artery and vein

Lens is composed of

crystalline proteins

Anterior segment of lens is

between the cornea and lens

Anterior chamber

between cornea and iris

posterior chamber

between iris and lens

Anterior segment of lens contains

watery aqueous humor

Posterior segment of lens goes from

lens to retina

posterior segment of lens

contains vitreous humor which transmits light, holds retina back in place, and resists deformation of eyeball

Auricle

fleshy external ear flap which funnels sound waves into meatus

External Auditory Meatus

Canal through temporal bone, contains short hairs and apocrine glands which make cerumen (ear wax) and terminates at tympanic membrane (eardrum)

Three ossicles that transfer sound waves from tympanic membrane to oval window

Malleus, Incus and Stapes

Auditory tube

equalizes ear pressure to outside atmosphere and contains a valve into nasopharynx which opens with yawn or swallow

Cochlea is split into three scalas

Scala vestibuli, scala tympani, cochlear duct

Scala vestibuli

superior chamber, space above vestibular membrane and starts at oval window

Scala tympani

inferior chamber, space below basilar membrane and ends at round window

Cochlear Duct

lies between vestibular and basilar membranes and contains endolymph because it is part of the membranous labyrinth

Vestibule

central section which contains oval window into cochlea

Semicircular canal

Posterior to vestible, 3 canals at right angles to each other

Membranous labyrinth

fibrous maze filled with endolymph and lies within bony labyrinth

Bony labyrinth

bony maze filled with perilymph

Cochlear Duct

Contains spiral organ, special sense is hearing, location is on basilar membrane of cochlear duct

Whithin vestibules there are

2 sacs

Utricle

superior and posterior and communicates with semicircular canals

Saccule

smaller and inferior and communicates with cochlear duct

Both sacs contains maculae

special sense of static equilibrium and afferent pathway is the vestibular branch of CN VIII

Each semicircular duct contains

a crest called crista ampullaris which special sense of dynamic equilibrium and is innervated by vestibular branch of CN VIII