the middle ear

where does the middle ear extend to and from?

tympanic membrane to lateral wall of inner ear

what is the main function of the middle ear?

transmit vibrations from tympanic membrane to inner ear via auditory ossicles

what are the 2 parts of the middle ear?

- tympanic cavity

- epitympanic recess

where is the tympanic cavity?

medial to tympanic membrane

what does the tympanic cavity contain?

the three auditory ossicles:

- malleus

- incus

- stapes

where is the epitympanic recess?

- superior to the tympanic cavity

- next to mastoid air cells

how do the auditory ossicles transmit sound waves from external to internal ear?

vibrations cause movement in tympanic membrane, which creates movement/oscillation in the auditory ossicles

which is the largest and most lateral ear bone?

malleus

where does the malleus articulate with the incus?

in the epitympanic recess

what are the 3 parts of the incus bone?

- 1 body

- short limb

- long limb

what does the body articulate with?

the malleus

what does the short limb attach to?

posterior wall of middle ear

what does the long limb attach to?

the stapes

what does the stapes attach to?

incus and oval window of inner ear

what shape is the stapes bone?

stirrup-shaped

what does the head of the stapes attach to?

long limb of incus

what does the base of the stapes attach to?

oval window

where are the mastoid air cells located?

posterior to epitympanic recess

what are the mastoid air cells?

collection of air-filled spaces in mastoid process of temporal bone

what is the cavity that contains the mastoid air cells called?

mastoid antrum

how does the mastoid antrum communicate with the middle ear?

via the aditus to mastoid antrum

what is the function of the mastoid air cells?

act as a buffer system of air, releasing air into tympanic cavity when pressure is too low

what are the 2 muscles associated with the middle ear?

- tensor tympani

- stapedius

what do the tensor tympani and stapedius contract in response to?

loud noise

what is the tensor tympani attached to?

malleus

what is the stapedius muscle attached to?

stapes

what do their contractions result in?

inhibits the vibrations of the malleus, incus and stapes - which reduces the transmission of sound to the inner ear

what is the action of these muscles called?

acoustic reflex

what is the auditory/eustachian tube?

cartilaginous + bony tube that connects the middle ear to the nasopharynx

what is the function of the auditory/eustachian tube?

equalises the pressure of the middle ear with that of the external acoustic meatus