Midterm Exam Weeks 4-6 Flashcards
divisions of the ear
- external
- middle
- internal
external ear components
- auricle
- external acoustic meatus
auricle
cartilage that captures waves and sound
- protects external auditory canal
external acoustic meatus
runs from auricle to tympanic membrane and directs sound waves into the ear
- lateral 2/3 is cartilage
- medial 1/3 is temporal bone
external acoustic meatus components
- ceruminous glands (ear wax)
- debris trapping hairs
debris trapping hairs
give tactile sensation and prevent things from further entering the ear
bony components of the external ear
- temporal bone
- external acoustic meatus
tympanic membrane
- separates the external and middle ear
- vibrates in response to incoming sound waves
- clear, thin and transparent
middle ear
- collect and amplify sound waves
- transmits sound to internal ear
features of the middle ear
- tympanic membrane
- auditory ossicles
- eustachian tube
pharyngotympanic tube
connects nasopharynx to the ear
ottis media
- swelling
- redness
- pain
auditory ossicles
- 3 bones
- bony ossicles
- connect tympanic membrane and internal ear
bony ossicles
- malleus (hammer) - points to interior tympanic membrane
- incus (anvil) - attaches malleus to stapes
- stapes (stirrup) - covers oval window
pathway of sound
- tympanic membrane
- vibration to malleus
- incus
- stapes
- oval window
muscles of the middle ear
- tensor tympani
- stapedius
- prevent excessive vibration of the bony ossicles to prevent large sound waves from damaging the ear
tensor tympani
pulls on malleus to increase stiffness and limit movement of tympanic membrane
stapedius
pulls on stapes to restrict movement at oval window
oval window
stapes pushes against oval window to transmit sound waves to internal ear
round window
helps sound waves travel through internal ear
***smaller
internal ear
- innermost compartment
- encased in temporal bone
- sensations of hearing and balance
internal ear components
- bony labyrinth
- membranous labyrinth
- perilymph
- endolymph
cochlea
- fluid-filled sensory organ for hearing
- sound travels through fluid as pressure waves and sends sound information to the brain
vestibule (utricle and saccule)
for balance and equilibrium/ stability and posture
detects:
1. head position
2. gravity
3. linear acceleration
3 semicircular canals
- detects rotational motion in 3 different planes
- maintains balance
sensory hair cells
- cells with hair-like projections (stereocilia)
- detects motion when hair cells are bent
- hearing and balance
sterocilia
hair-like projections that send neurotransmitters to nerves
1. increases neurotransmitter release when hear
2. decreases neurotransmitter release when stop hearing
which portion of the cochlea contains endolymph
cochlear ducts
sound
- pressure conducted through a medium
- vibration in air
amplitude of sound
- height of sound wave
- volume of sound
- decibels (DB)
***higher sound wave=higher sound
frequency of sound
- how close together waves are
- pitch of sound
- hertz (Hz)
***closer together waves=higher pitch
sounds transmission
- sound 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
components of cochlea
- cochlear duct (scala media)
- helicotrema
- scala vestibuli (oval window)
- scala tympani (round window)
- organ of corti
sound transmission in cochlea
- how many hair cells stimulated is determined by how loud you hear the sound
- low frequency noises travel all the way to helicotrema
- high frequency noises only travel to middle of cochlea
endolymph vs. perilymph
endolymph: cochlear duct
perilymph: scala vestibuli and scala tympani
components of organ of corti (spiral organ)
- tectorial membrane
- hair cell (sit on basilar membrane, and in contact with tectorial membrane)
- basilar membrane
organ of corti
- waves in perilymph move basilar membrane up and down
- sterocilia of hair cells are pushed against and pulled away from tectorial membrane
innervation of hearing
CN VIII
- transmit information to the brainstem
process of hearing
- sound waves cause vibration of tympanic membrane
- movement of tympanic membrane vibrates ossicles (amplify sound)
- stapes pushing against 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
- cerumen (earwax) buildup
- perforated tympanic membrane
sensorineural hearing loss
internal ear/nerve pathway
- usually permanent
- cochlear/nerve degeneration caused by aging
- trauma induced sensory cell damage
the receptors of the internal ear responsible for the detection of sound are termed
hair cells
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 and utricle
planes of the semicircular canals
- anterior (YES)
- posterior (side to side - roll)
- lateral (NO)
semicircular canals
- membranous labyrinth filled with endolymph
- each duct is continuous with utricle
- each duct contains an ampulla
- hair-cells are clustered together on the ampulla - cristae ampullaris
ampulla
swollen region containing sensory receptors
cupula
sensory hair cells embedded in gelatinous mass on semicircular canals
- stimulates hair cells when endolymph pushes against
sensing rotational movement - the steps
- 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
- neurotransmitters stimulate nerves
saccule and utricle - the vestibule
membranous sacs filled with endolymph
- each sac contains a macula
utricle: horizontal acceleration
saccule: vertical acceleration
macula
contains hair cells in the utricle and saccule
otoliths
crystals that are heavy and lag behind
movement of otoliths
movement of dense otoliths stimulates hair cells which release neurotransmitters and send neural signal
head normal vs head tilted
when you tilt your head gravity pushes the otoliths downhill distorting hair cell processes so the receptor output increases
bony orbit
bilateral, symmetrical cavities containing the eyeballs and associated structures
bones that make up the bony orbit
- frontal bone - anterior
- sphenoid bone - posterior
- ethmoid bone - medial
- lacrimal bone - anterior medial wall
- palatine bone - hard palate
- maxilla - anterior and floor
- zygomatic bone - lateral
superior orbital fissure
- oculomotor nerve CN III
- trochlear nerve CN IV
- opthalamic division of trigeminal nerve CN V1
- abducens nerve CN VI
*** all travel through
optic canal
optic nerve CN II travels through
components of the bony orbit
- superior orbital fissure
- inferior orbital fissure
- optic canal
layers of the eye
- outer fibrous layer
- middle vascular layer
- inner neural layer
outer fibrous layer
- sclera
- cornea
middle vascular layer
uvea:
1. iris
2. ciliary body
3. choroid
inner neural layer
- retina
cornea
- first refraction of light entering eye
- directs light in to lens
- avascular (no blood vessels)
- clear layer
scelera
- supportive outer white layer
- attachment site for extraocular muscles
- covered by mucous membranes (conjuctiva) to lubricate eye
- vascular (blood vessels)
limbus
transition zone between cornea and sclera
iris
- contains pupillary dilator and sphincter muscles
- controls pupil size depending on light and nervous system signals
- goes around pupil
ciliary body
- produces aqueous humour
- contains ciliary muscles
- helps focus lens using zonular fibres and ciliary muscles
zonular fibres
attach from ciliary body to lens
lens
focuses light on the retina
- majority of refractions
choroid
- very vascularized between sclera and the retinoid
- nourishes retina
- maintains eye temperature and volume
intraocular muscles vs extraocular muscles
intra: within the eye
extra: outside the eye
ciliary muscles
form a ring around the eyeball
when looking at something far away what happens to the ciliary muscles
- ciliary muscles relax
- zonule fibres tense
- lens flattened for focusing on distant objects
when looking at something close by what happens to the ciliary muscles
- ciliary muscles contract
- zonule fibres relax
- lens rounded (thickens) for focusing on close objects
pupillary muscles
- sphincter pupillae
- dilator pupillae
what is color of the iris determined by
amount of melanin
sphincter pupillae
- concentric muscle fibres
- constricts pupil when contracted
- parasympathetic NS
***rest and digest so dont need to let as much light in
dilator pupillae
- muscle fibres run longitudinally towards margins of the iris
- enlarges pupil when contracted
- sympathetic NS
*** fight or flight so let more light in to be aware
bright light or PSNS signals
sphincter pupillae
- pupil constricts
dim light or SNS signals
dilator pupillae
- pupil dilates
retina
captures light to send to the brain
components of the retina
- macula (fovea in centre)
- optic disc
- ora serrata
- optic nerve
- fovea
macula of retina
highest concentration of photoreceptor cells
optic disc
- where optic nerve exits the eye
- blind spot - no photoreceptors
ora serrata
anterior border of the retina
optic nerve
accumulation of the retinal axons
fovea
has sharpest vision
- physical dip that pushes vascular aside so light can directly go to the photoreceptors
photoreceptors
rods and cones
myotopia (near-sightedness)
image is focused in front of fovea
- lens is too long/bulbous
hypertopia (far-sightedness)
image is focused behind the fovea
- lens is too short/flat too
chambers of the eye
anterior cavity:
1. anterior chamber
2. posterior chamber
posterior cavity:
1. vitreous chamber (largest)
anterior chamber
- between cornea and the iris
- filled with the aqueous humous
aqueous humour
- maintains ocular (eye) pressure
- replaced every 90 minutes
posterior chamber
- between iris and the lens
- important for production and circulation of aqueous humour
vitreous humour
- maintains shape of the eye
- nourishes the eye
- attached to retina
- makes up about 80% of the eye volume
- does not regenerate
vitreous chamber
filled with gel-like vitreous humour
extraocular muscles
- superior rectus (top of eye)
- inferior rectus (bottom of eye)
- lateral rectus
- medial rectus
- superior oblique
- inferior oblique
- levator palpebrae superioris
superior oblique
goes through a pully - trochlea - and attaches on the posterior lateral side
***angle
inferior oblique
comes from medial orbit directly from bone and attaches to posterior lateral eyeball
***angle
levator palpebrae superioris
attaches to upper eyelid and is responsible for opening the eye
movement of the superior rectus
contracts and pulls the eye up
movement of the inferior rectus
roll eye downward
movement of the lateral and medial rectus
lateral: roll eye laterally
medial: roll eye medially
movement of the superior oblique
down and out
movement of the inferior oblique
up and out
innervation of the extraocular muscles
oculomotor nerve CN III
EXCEPTION: SO4LR6
- superior oblique (SO) and lateral rectus (LR)
superior oblique innervation
trochlear nerve CN IV (4)
***trochlea = pulley
lateral rectus innervation
abducens nerve CN VI (6)
- abducens abducts
lacrimal apparatus
- system of glands and ducts
- produces and drains lacrimal fluid (tears)
lacrimal fluid
- lubricates eye surface
- removes debris from the eye
- about 1 mL produced each day
components of the lacrimal apparatus
- lacrimal gland
- excretory lacrimal ducts
- superior and inferior puncta (lacrimal fluid drained)
- superior and inferior lacrimal canaliculi
- lacrimal sac
- nasolacrimal duct
the nasal cavity
- divided into left and right side
- has midline and lateral walls
- has roof and floor
functions of the nasal cavity
- humidify, warm and filter the air
- facilitate drainage of the paranasal sinuses
- secrete mucus
external nose
- projects outwards allowing air to enter the nasal cavity
- made up of bone and cartilage
neurocranium of nose
- frontal bone
- cribriform plate
- ethmoid bone
- sphenoid bone
viscerocranium of noses
- nasal bone
- vomer bone
- maxillary bone
- inferior nasal concha
bones in the nasal cavity
- frontal bone
- nasal bone
- ethmoid bone
- sphenoid bone
- vomer bone
- palatine bone
- maxillary bone
medial wall of the nasal cavity
nasal septum
nasal septum
wall made up of a bony portion and a cartilaginous portion
components of the nasal septum
- ethmoid bone
- vomer bone
- septal cartilage
deviated septum
nasal septum that does not run across the midline (bends to side)
lateral wall of the nasal cavity
conchae and meatuses
conchae and meatuses
- superior nasal concha
- middle nasal concha
- inferior nasal concha
- superior nasal meatus
- middle nasal meatus
- inferior nasal meatus
meatus
space between the concha
nasal conchae
- superior and middle conchae are processes of the ETHMOID bone
- inferior concha is formed by ITS OWN BONE
functions of the nasal conchae
- increase surface area in the nasal cavity (air we breathe in stays in concha for longer)
- humidify air
- filter air (covered in mucus)
- warm up air
roof of the nasal cavity - medial
- cribriform plate
- nasal bone
- frontal bone
- sphenoid bone
roof of the nasal cavity - anterior
- frontal bone
- nasal bone
- sphenoid bone
roof of the nasal cavity - superior
- frontal bone
- cribriform plate
- ethmoid bone
- sphenoid bone
floor of the nasal cavity
palate
1. palatine bone
2. maxillary bone
cartilage of the external nose
- lateral nasal cartilage
- major alar cartilage
- minor alar cartilage
paranasal sinuses
- cavities (air pockets) found in the skull
- lined with respiratory mucosa and secrete mucous
bones with paranasal sinuses
- ethmoid
- frontal
- maxillary
- sphenoid
function of the paranasal sinuses
- lighten weight of the skull due to air pockets
- humidify/heat/filter inspired air
- secrete mucus
***nasal meatuses receive drainage from the paranasal sinuses
what drains into the superior meatus
- sphenoid sinus
- posterior ethmoid sinuses
what drains into the middle meatus
- frontal sinus
- anterior ethmoid sinus
- maxillary sinuses
where is the mucus swallowed after drainage
nasopharynx