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UB ANA 113 Lec 20
The Ear
Question | Answer |
---|---|
What are the 3 principle regions of the ear | External ear, middle ear, Inner ear |
auricle | EXTERNAL EAR. Gathers sound |
External auditory meatus | EXTERNAL EAR. s-shaped tube. Outer 2/3 cartilage, Inner 1/3 = Bone |
Why is the external auditory meatus a certain shape | S-shape discourages things from flying in. |
Purpose of hair and glands in ear | collect dust |
cerumenous glands | secrete wax to repel insects |
cerumen | ear wax. sticky and unpleasant odor |
otitis externa | "swimmers ear". Inflammation of the external acoustic meatus due to an accumulation of bacteria |
Tympanic membrane | EXTERNAL EAR. ear drum. Separates outer ear from middle ear |
What are the three layers of the tympanic membrane | outer - modified skin. middle - fibrous. inner - mucous |
How can you see the tympanic membrane? | Pull auricle posterior and superior |
Why would you want to look at the tympanic membrane? | You can see through it into the middle ear to view the bone (malleus) and see if fluid is present |
Where is the tympanic cavity located? | In the middle ear |
Another name for the Auditory tube | eustachian tube |
Auditory/Eustachian tube location | connects middle ear with the nasal pharynx |
Otitis media | Middle ear infection. -Auditory/Eustachian tube is horizontal in children and bacteria can easily travel from the nasal pharynx to the middle ear |
What are the ossicles of the middle ear | Malleus, Incus, Stapes |
Malleus | "hammer". Connected to the tympanic membrane |
Incus | "anvil". In between the malleus and stapes |
stapes | "stirrup" connected to the beginning of the inner ear (oval window) |
Where are the structures for hearing and equilibrium located? | in the structures of the inner ear |
What are the 2 portions of the "labyrinth"? | outer bony and inner membranous |
Cochlea | "snail part" of inner ear |
Where are perilymph and endolymph found? | As part of the cochlea |
Perilymph | fluid outside membranous tube of cochlea |
endolymph | fluid inside membranous tube of cochlea. Allows the tube to float |
Organ of corti | INNER EAR. Allows for "hearing". Inside tubes of cochlea. Hair cells move and send electrical impulse to brain. |
Auditory pathway | sound->tympanic membrane->stapes->hit oval window->hit membrane->fluid produce waves->hair cells &organ of corti move->electrical impulse->CN VIII->nucleus of VIII in medulla->thalamus->temporal lobe |
Vestibular apparatus | Equilibrium |
semicicular canals | (3) Sense dynamic equilibrium |
utricle and saccule | sense static equilibrium |
dynamic equilibrium | movement |
static equilibrium | position of head |