ear anatomy Flashcards
what is the auricle
The pinna, also called the auricle, is made up of cartilage that gives our ears their various shapes and sizes, and it also has a fleshy bit at the bottom- called the ear lobe, or lobule.
what does the pinna do
The pinna directs sound waves towards the opening of the ear canal.
what is the external acoustic meatus and what does it do
The ear canal, or the external acoustic meatus, is a short, curved tube that burrows through the temporal bone for about 1 inch - or 2 and a half centimeters - and ends at the tympanic membrane.
what is cerumen and what does it do
sticky, yellow-ish, earwax.
Cerumen helps prevents foreign objects or tiny insects from getting in and damaging the tympanic membrane.
what secretes ear wax
the ear canal is covered by skin, along with hair follicles and ceruminous glands - which secrete cerumen
what is the correct term for the ear-drum?
The tympanic membrane is also called the eardrum,
what cavities does the tympanic membrane divide
the external ear from the middle ear
what is the function of the tympanic membrane
When sound waves reach the eardrum, it vibrates and transmits those vibrations to the tiny bones in the middle ear.
what is the middle ear
an air-filled cavity inside the temporal bone, shaped like tiny chamber with 4 walls, a floor and a roof.
what forms the lateral wall of the middle ear
eardrum/tympanic membrane
what holes are in the medial wall of the middle ear
The internal wall has two windows: an oval window above, and a round window below.
what cavities does the medial wall of the middle ear separate?
separates the middle ear from the inner ear.
where is the mastoid antrum and what does it do
The posterior wall of the middle ear has an opening called the mastoid antrum, and it connects the middle ear with the mastoid cavity within the temporal bone.
what is the Eustachian tube?
also called the nasopharyngeal tube - tube from middle ear to nasopharynx
what are the 3 fx of nasopharyngeal tube?
-equalizing pressure across the tympanic membrane
-protecting the middle ear from reflux of fluids going up from the nasopharynx,
-clearing out middle ear secretions.
what is the roof of the middle ear called?
tegmen tympani
what is the roof of the middle ear called?
tegmen tympani/tegmental wall/
epitympanic recess is a dome shaped cavity above the ossicles
what forms the floor of the middle ear?
the floor of the middle ear is a thin layer of bone that sits right above our friendly basement neighbor - the jugular vein.
how is sound transmitted through the middle ear?
“handle” of the malleus rests on the eardrum
when the eardrum vibrates, the vibrations are transmitted from the malleus to the incus, then to the stapes, and finally to the oval window, which transfers the vibrations over to the inner ear.
what fluid fills the bony labyrinth
perilymph
what fluid fills the membranous labyrinth
endolymph
what is the inner ear also called?
labyrinth
what is responsible for hearing
cochlea
which part of inner ear is responsible for balance seeing
semicircular canals x3
what sense(s) do the movement of perilymph and endolymph contribute to?
hearing and balance
Where is the membranous labyrinth
inside the bony labyrinth
What is the vestibule?
like a hallway that leads up to two other parts or rooms - the cochlea, towards the front of our head, that deals with hearing, and a second room containing the three semicircular canals, towards the back, which play a role in balance.
what and where is the Scala vestibuli?
in the inner ear, the cochlea is like a snails shell… if you look at in cross section, the Scala vestibuli is the top
connected to the middle ear through the oval window, and contains perilymph.
what is the Scala tympani?
in the inner ear, the cochlea is like a snails shell… if you look at in cross section the Scala tympani is the bottom
connected to the middle ear through the round window, and it also contains perilymph.
what is the organ of Corti also called?
The organ of hearing, called the spiral organ, or the organ of Corti, is fixed to the basilar membrane and contains hair cells. The tips of these hair cells insert into the tectorial membrane,
what is the tectorial membrane
tectorial membrane,
a gelatinous membrane that overlies the spiral organ.
in the inner ear, what is responsible for transducing sound waves into signal we can interpret?
The organ of Corti is the mastermind of our hearing sense, and it contains our hearing receptors, or hair cells.
summarise how sound enters ear and is received
sound vibrations travel through external ear to ossicles in middle ear
malleus>incus>stapes
stapes against oval window transmits vibrations to perilymph (scala vestibuli) which transmits to the organ of Corti (in cochlear duct)
Hearing receptors convert vibrations into an electrical impulse.
1)to brain via CN8
2)perilymph (in scala tympani) is also set in motion - round window bulge back towards middle ear, relieving pressure.
which nerve takes auditory signal to brain
CN8
What angle are the semi circular canals from each other?
90degrees - three planes of motion