orbit and ear

palpebral fissure

opening between eyelids allowing passage of light into eyeball

layers of eyelid

skin

subcutaneous tissue

voluntary muscle (plapebral part of orbicularis oculi)

orbital septum

tarsus

conjuctiva

orbital septum

extension of periosteum from margin of orbit into eyelids

tarsus

plate of dense connective tissue supporting eye

superior tarsus

associated with muscles which raise upper eyelid

tarsal glands

embedded within tarsal plates

empty oily secretions onto free magin of each eyelid

conjuctiva

membrane covering posterior surface of each eyelid

reflects onto sclera

attaches to eyeball at junctio between sclera and cornea

conjuctival sac

forms when eyelids are closed with superior and inferior folds

supra-orbital artery

arises from opthalmic artery exiting orbit anteriorly through supra-orbital notch (foramen)

joins network of muscles aound orbit

supra-orbital vein

parallels supra-orbital artery passing posteriorly through supra-orbital notch (foramen0 to enter orbit

joins with opthalmic veins

lacrimal apparatus

involved in production, movement, and drainage of fluid from surface of eyeball

lacrimal gland

larger orbital part in frontal bone

smaller palpebral part in superolateral upper eyelid

ducts empty secretions into superior fold of conjuctiva

blinking

spreads fluid on eyeballs from lateral to medial

lacrimal canaliculi

drains fluid from eyeball into lacrimal sac

outer fibrous layer of eyeball

formed of cornea anteriorly and sclera posteriorly

middle vascular layer of eyeball

coninuous with ciliary body and iris anteriorly with choroid posteriorly

inner layer of eyeball

consists of ciliary body and iris anteriorly with optic part of retina posteriorly

anterior chamber of eyeball

between cornea and iris

posterior chamber of eyeball

between iris and lens

auqueous humor

fills eyeball

supplies nutrients to avascular cornea and iris

maintains intra-occular pressure

lens

transparent biconvex elastic disc

separates anterior 1/5 of eyeball

vitreous body

transparent, gelatinous substance within vitreous chamber

fills eyeball from lens to retina

sclera

whites of eyes

dense connective tissue

cornea

transparent layer bulging anteriorly from eyeball

allows light to enter eyeball

iris

most external part of vascular layer

colored part of eye around pupil

contains muscles to control size of pupil

ciliary body

middle portion of vascular layer forms a ring around anterior eyeball

ciliary processes

projections from inner surface of ciliary body

fiberous sxtensions form suspensory ligament of lens

suspensory ligament of lens

suspends lens in proper position

choroid

most internal portion of vascular layer

thin, highly vascular, pigmented layer adjacent to renina

retina

inner layer of eyeball

nonvisual retina

anterior

covers internal surface of ciliary body and iris

optic retina

posterior and lateral

sensitive to light

contains optic disc

optic disc

site where optic nerve leave retina

external ear

captures sound

middle ear

converts sound into mechanical signals

inner ear

converts mechanical signals into electrical signals and contains receptors for motion and position

auricle of the external ear

formed of elastic cartilage covered with skin on lateral side of head

assist in capturing sound

helix

outside rim of ear ending inferiorly at fleshy lobule

concha

hollow center of external ear with exteral aucoustic meatus in its depths

external acoustic meatus

extends from deppest parts of chocha to tympanic membrane

tympanic membrane

separates external acoustic meatus from middle ear

connective tissue line with skin externally and mucous internally

malleus

bone of middle ear attached to tympanic membrane

tympanic cavity

medial to tympanic membrane

epitympanic recess

superior to tympanic cavity

auditory ossicles

form osseous chain from tympanic membrane to oval window

incus

intermediate bone of inner ear

stapes

most medial auditiory ossicle

fits into oval window

mastoid air cells

air-filled spaces in mastoid part of temporal bone

continuous with middle ear

inner ear

housed in petrous part of temporal bone

conveys info to brain about balance and hearing

bony labyrinth

vestibule, semicircular canals, and cochlea

vestibule

central part of bony labyrinth

oval window on lateral wall

communicates with semicircular canals and cochlea

semicircular canals

project posterosuperiorly from vestibule

anterior, posterior, and lateral

one end of each dilated to form ampulla

cochlea

projects anteriorly from vestibule

(snail shell)

cochlear duct

spirals throughout cochlea creating 2 canals

scala vestibuli

duct in cochlea continuous with vestibule

scala tympani

duct in cochlea separated from middle ear by secondary tympanic membrane at round window

helicotrema

connects cochlear ducts at apex

membranous labyrinth

continuous system of membranous ducts and sacs filled with endolymph

suspended within perilymph of bony labyrinth

contains organs of balance and organ of hearing

organs of balance

semicircular ducts, utricle, and saccule

organ of hearing

cochlear duct within cochlea

utricle

larger sac located in posterosuperior part of vestibule

semicircular ducts empty here

saccule

smaller sac located in anteroinferior vestibule

cochlear duct empties here

utriculosaccular duct

connects urticle and saccule and estabilishes continuity between all compnents of mebranous labyrinth

macula of utricle

responds to linear acceleration in horizontal plane

macula of saccule

reponds to linear acceleration in vertical plane

crista within ampulla of semicircular ducts

respond to rotational acceleration

cochlear duct

occupies central cochlea

spiral organ

oragn of hearing resting on basilar membrane, projects into cochlear duct

spiral ligament

outer wall of cochlear duct

vestibular membrane

roof of cochlear duct

basilar membrane

floor of cochlear duct