eye and ear Flashcards
what is the bony orbit
bilateral, symmetrical cavities containing the eyeballs and associated structures
bones of the bony orbit anterior/lateral view
- frontal bone
- sphenoid bone
- ethmoid bone
- lacrimal bone
- palatine bone
- maxilla
- zygomatic bone
bones of the bony orbit medial view
- frontal bone
- sphenoid bone
- zygomatic bone
- maxilla
- palatine bone
holes within the bony orbit
superior orbital fissure
inferior orbital fissure
optic canal
nerves related to superior orbital fissure
- oculomotor nerve (CN III)
- trochlear nerve (CN IV)
- ophthalmic division of trigeminal nerve (CN V1)
- abducens nerve (CN VI)
nerves related to optic canal
optic nerve
layers of the eye
outer fibrous layer
middle vascualr layer
inner neural layer
outer fibrous layer
sclera and cornea
middle vascular layer
Uvea: iris, ciliary body, choroid
inner neural layer
retina
cornea
- first refraction of light entering the eye
- directs light to lens
- avascular
sclera
- supportive outer white layer
- attachment site for extraocular muscles convered by mucous membranes (conjunctive) to lubricate eye
- vascular
limbus
transition zone between cornea and sclera
iris
- contains pupillary dilator and sphincter muscles
- controls pull size depending on light and nervous system
ciliary body
- produces aqueous humour
- contains ciliary muscles
- helps focus lens using zonular fibers and ciliary muscles
lens
focus light on retina
intraocular
within the eye
extraocular
outside the eye
ciliary muscles
form ring around the eye
what happens when ciliary muscles are relaxed
they expand
- zonular fibers tense
- lens flattened for focusing on distant objects
what happens when ciliary muscles constict
- they contract
- zonular fibers relax
- lens are rounded for focusing on close objects
explain what happens with the ciliary muscles when viewing distant object
- ciliary muscles relax
- zonular fibers tighten
- lens flatten
explain what happens with the ciliary muscles when viewing close object
- ciliary muscles contract
- zonular fibers relax
- lens thickens
which of the following is true?
1. when viewing distant objects, the ciliary muscles contract, which tenses the zonular fibers and flattens the lens
2. distant objects, the ciliary relax, which relaxes the zonular fibers and flattens the lens
3. near objects, the ciliary contract, relaxing the zonular and thickens the lens
4. near objects, ciliary relax, tensing the zonular fibers and flattens the lens
3.
pupillary muscles
dilator pupillae
sphincter pupillae
dilator pupillae
- muscle fibers run longitudinally towards margins of iris
- enlarges pupil when contracted
- sympathetic NS
sphincter pupillae
- concentric muscle fibers
- constricts pupil when contracted
- parasympathetic NS
bright lights or PSNS to pupillary muscles
sphincter pupillae- contracted
dilator pupillae- not contracted
makes pupil smaller
dim light or SNS signals to pupillary muscles
sphincter pupillae- not contracted
dilator pupillae- contracted
makes pupil larger
choroid
- nourishes retina
- maintains eye temperature and volume
parts of the inner neural layer/retina
- macula (fovea in centre)
- optic disc
- ora serrata
- optic nerve
macula (fovea in center)
- highest concentration of photoreceptor cells
optic disc
- where optic nerve exits the eye
- blind spot: no photoreceptors
ora serrata
anterior border of retina
optic nerve
accumulation of retinal axons
chambers of the eye
anterior cavity: (anterior chamber, posterior chamber)
Posterior cavity: Vitreous chamber
what is the largest chamber of the eye
vitreous chamber
posterior chamber
- between the iris and lens
- important for production and circulation of aqueous humor
anterior chamber
- between cornea and iris
- filled with aqueous humour
aqueous humour
- maintains ocular (eye) pressure
- replaced every 90 min
vitreous chamber
filled with vitreous humour
vitreous humour
- maintains shape of eye
- nourishes eye
- attached to retina
- makes up about 80% of eye volume
- does not regenerate
what are the extraocular muscles
- superior rectus
- lateral rectus
- inferior oblique
- superior oblique
- medial rectus
- inferior rectus
- levator palpebrae superioris
superior rectus
pulls eye up
lateral rectus
pulls eye laterally
inferior oblique
up and out
superior oblique
down and out
medial rectus
pulls eye medially
inferior rectus
pull eye downward
lateral rectus innervation
abducens nerve (CN VI)
superior oblique innervation
trochlear nerve
innervation of the extraocular muscles
oculomotor nerve
except (“SOLAR”)
(lateral rectus)
(superior oblique)
lacrimal apparatus
system of glands and ducts
- produces and drains lacrimal fluid
lacrimal fluid
- lubericate eye surface
- removes debris from eye
- about 1mL produced each day
part of the lacrimal apparatus
- lacrimal gland
- excretory lacrimal ducts
- superior and inferior puncta
- superior and inferior lacrimal canaliculi
- lacrimal sac
- nasolacrimal duct
divisions of the ear
- external
- middle
- internal
parts of the external ear
auricle
external acoustic meatus
auricle
- cartilage
- captures waves and sound
- protects the opening of the ear
- funnels sounds
external acoustic meatus
from auricle –> tympanic membrane
lateral–> cartilage
medial–> temporal bone
- directs sounds waves into the ear
- ceruminous glands
- debris trapping hairs
boney components of external ear
temporal bone
tympanic membrane
- separates the external and middle ear
- vibrate in response to incoming sound waves
where does the external acoustic meatus end
1. tympanic membrane
2. vestibule
3. auditory tube
4. oval window
1.
features of the middle ear
- collect and amplify sound waves
- transmits sound to internal ear
- (auditory ossicles, tympanic mem, eustachian tube, path to nasopharynx)
pharyngotympanic tube
matches pressure with the body
connects ear–> nose –> throat
what do auditory ossicles do?
- three bones
- bony ossicles
- connect tympanic membrane and internal ear
the three bony ossicles
malleus–> incus–> stapes–> covers oval window causing it to vibrate
muscles of middle ear
tensor tympani –> pulls on malleous
stapedius –> pulls on stapes
(prevents excessive vibration of the bony ossicles)
oval window
- stapes pushed against oval window to transmit sound waves to internal ear
round window
helps sound waves travel through internal ear
- like an outlet helps flow
(below oval window)
features of internal ear
- innermost compartment
- encased in temporal bone
- sensations of hearing and balance
what is the internal ear composed of
- bony labyrinth
- membranous labyrinth
bony labyrinth
- cochlea
(cochlear duct) - vestibule
(utricle and saccule) - 3 semicircular canals
(semicircular ducts)
cochlea
- fluid filled
- sensory organ for hearing
- sound travels through the fluid
- sends sound information to the brain
vestibule
- membranous labyrinth
- utricle and saccule
- balance and equilibrium
- detects:
head position
gravity
linear accerlation - maintain stability and posture
semicircular canals
3 semiciruclar canals
- detects rotational motion in 3 different planes
- maintain balance
sensory hair cells
cells with hair like projections
(sterocilia)
- detects motion
(hair cells get bent)
- hearing and balance
which portion of the cochlea contain endolymph?
1. the Scala vestibuli
2. bony labyrinth
3. cochlear duct
4. tympanic duct
3
what does the membranous labyrinth contain?
- endolymph
amplitude
volume of sound
- height of sound wave
- decibels (dB)
frequency
pitch of sound
- how close together waves are together
- hertz (Hz)
sound transmission
- sounds waves transmitted through external ear to tympanic membrane
- vibrations pass through ossicles of middle ear
- stapes pushes against oval window and sound waves are transmitted to cochlea
parts of the cochlea
- scala tympani
- scala vestibuli
- chochlear duct (scala media)
- helicotema
high pitch
doesnt travel as far into the cochlea
low pitch
travels far within the cochlea
how is sound determined
- how many hair cells are stimulate determine how loud you hear
- pitch is determined by pressure in cochlea
what does the cochlear duct house?
sensory organ of corti
organ for hearin/spiral organ
innervation of hearing
CN VIII
whole process of hearing
- sound waves cause vibration of the tympanic membrane
- movement of tympanic membrane vibrates ossicles
- stapes pushings oval window causes waves in perilymph
- waves of perilymph push against basilar membrane as they travel through the cochlea
- hair cells push against tectorial membrane and when they bend a neural signal is transmitted
- impulses travel to CNS via cochlear branch of CN VIII
conductive hearing loss
-external or middle ear
- usually temporary
(earwax build up)
(perforated eardrum)
sensorineural hearing loss
- internal ear/nerve pathway
- usually permanent
(cochlear/nerve degeneration by again)
(trauma induced)
the receptors of the internal ear responsible for the detection of sound are termed?
1. tactile receptors
2. hair cells
3. proprioceptors
4. baroreceptors
2
vestibular apparatus
vestibule
semicircular canals
dynamic equilibrium
maintaining balance when head and body are moved suddenly
- semicircular ducts
static equilibrium
maintaining posture and stability when body is motionless
saccule anular utricle
posteior semicircular canals
head side to side
lateral semicircular canals
shaken head (‘no’)
anterior semicircular canals
shaking head “yes”
rotational movement
hair cells get activated with movement to get more information
ampullar: semicircular canals
- each duct contain an ampulla
- swollen region containing sensory receptors
- hair cells are clustered together on parts of the ampulla
what are hair cells embedded in
gelatinous mass
cupula
cupula
emphym cause cupula to move which stimulates hair cells
process of sensing rotational movement
- head rotates and causes movement of endolymph
- semicircular canal rotates with the head and endolymph sloshes against cupula
- displacement of cupula distorts the sensory hair cells
- nerve impulses are transmitted during this displacement/movement
saccule and utricle
membranous sacs filled with endolymph
each sac contains a macula (hairs cells in macula)
Utricle: horizontal acceleration
saccule: vertical acceleration
macula
contains otoliths
otoliths
- crystals are heavy and lag behind
- gravity causes them to move the causes hair cells to move
