Ear Flashcards
which bone houses the cavities of the ear?
name its 4 components
The Temporal Bone
what is the petrous bone?
in relation to temporal bone parts, the external acoustic meatus consists mostly of the___________
tympanic plate
parts of ear
what goes through the internal acoustic meatus? which cranial fossa does it lie in?
facial and vestibulocochlear cranial nerves.
7 & 8
Right ear
Process of the mallelous is pointing to the left
what do u find inside a cutt section of the mastoid process?
it has several air filled spaces within it called the mastoid air cells
ALAA “cells” in this context = small spaces
what muscles attatch to the mastoid process?
sternocleidomastoid and digastric muscles
how does the mastoid air cells communicate with the middle ear cavity? clinical relevance
Label ear
label the External Ear
anatomy of external acoustic meatus
How long is it?
- cartilaginous tube laterally ( (outer 1/3) )
- bony canal medially lying in the temporal bone. ((inner 2/3) )
2.5 cm
how can we view the ear?
bc the ear canal is Sigmoid shape>> need to pull ear up and back to
straighten when examining
what forms the WAX of the ear?
The meatus is lined by skin secreting cerumen (which is modified sebum) that gives protection for the delicate meatal skin.
The discarded cells of the skin together with cerumen form the>>> WAX
Despite similarities in their names, the internal and external acoustic meatus are not one continuous bony channel! !!!
chill ok
describe the fibrous tympanic membrane
“ear drum” shallow cone with its apex pointing medially.
It is translucent allowing visualisation of some structures within the middle ear, most notably, the malleus to which the apex of the eardrum is attached.
Middle ear anatomy And function
Ossicles and an Air Filled Cavity
The middle ear, or the tympanic cavity, contains the ossicles that transmit vibrations from the tympanic membrane to components of the inner ear.
The middle ear cavity is air-filled and enclosed from the external environment.
Bones of middle ear? Function and how r they connected?
The handle of the malleus is attached to the tympanic membrane while its body articulates with that of the incus. The incus then articulates with the stapes then opens at oval window
Connected via synovial joints and relay vibrations from the tympanic
membrane to the oval window of the cochlea (inner ear)
- Transmitting vibration from an air medium to a fluid-medium
- The ossicles amplify and concentrate sound energy from the eardrum to the oval window.
look how tiny they r
How does middle ear communicate w/ the external environment ?
via the pharyngotympanic (Eustachian) tube when this opens
pharyngotympanic (Eustachian) tube anatomy & functions
How do u open the pharyngotympanic (Eustachian) tube?
The pharyngotympanic (Eustachian) tube is usually closed, it opens by the pull of attached palate muscles when swallowing or yawning.
You might have noticed this as your ears ‘popping’.
how does the Pharyngotympanic tube differ in children?
Important Anatomical Relations of the Ear
which nerve has an important relationship w/ the middle ear?
anatomy of the Inner Ear and function
The inner ear, also called the labyrinth “maze”
consists of a series of channels or canals hollowed out of the petrous temporal bone (the bony labyrinth) which surround a series of tubes or ducts, known as the membranous labyrinth.
The cochlea converts vibration into an electrical signal (action potential) which is perceived as sound
The vestibular apparatus is involved in maintaining our sense of position and balance
Label vestibular apparatus
The ducts (“tubes”) forming the membranous labyrinth are shaped to form
4 structures:
what r these ducts filled with?
All of these ducts are filled with endolymph.
what about the bony labyrinth ?
surrounds and mirrors the shape of these membranous ducts (tubes).
These bony shapes are called ‘canals’
- the bony labyrinth surrounding the semicircular duct is called the semicircular canal
- the bony labyrinth surrounding the utricle and saccule is the vestibule.
- Between the membranous and bony labyrinth is a fluid called perilymph.
anatomy of cochlea
what sets up movements of the fluid in the cochlea?
The cochlea is our organ of hearing.
It is fluid filled tube.
Movements at the oval window set up movements of the fluid in the cochlea .
what r the special sensory cells in the cochlea? where r they located? what r their function?
in the organ of Corti!
Waves of fluid cause movement of special sensory cells (stereocilia) within the cochlear duct which generate AP in CN VIII
How do we hear?
what forms the components of the balance system? how do they coordinate balance?
The stereocilia in the utricle and saccule respond to rotational acceleration and the static pull of gravity,
while receptors in the semicircular ducts respond to rotational acceleration in three different planes (mirroring their arrangement).
what causes the stercocilia to bend?
Movement of the head and body leads to movement of fluid within these inner ear structures, causing the stereocilia to bend.
This “bending” generates an AP that is relayed via the vestibular part of the vestibulocochlear nerve, and is perceived as our sense of position and balance.
function of Stapes? innervation
tendon of stapes protrudes from the stapedius muscle and holds onto the stapes and pulls it backwards, restricting its movement, this is an advantage for us limiting loud sounds.
if stapes muscle cotnracts it will reduce the ossicular chan movements and prevent inner ear from excessive stimulation & prevent damge to the hair cells!
facial nerve!
facial nerve relation with middle ear?
label ear
label temoral bone parts
label the tympanic membrane
how do u know which is left or right?
this is the Normal Right Tympanic Membrane
function of round window?
This is the round window, an opening in the inner ear which is covered by a membrane. The round window, and its flexible membrane, is vital to allow movement of fluid within the cochlea. Without the round window, the stapes footplate would be pushing against a fluid-filled cochlea (via its action at the oval window) that would be uncompressable. As a result no movement of fluid would occur. The movement of fluid needs to occur to stimulate movement of the hair cells within the cochlea , so that electrical impulses can be generated down the cochlear nerve (allowing perception of sound i.e. hearing)
