7. The middle ear (lecture) Flashcards
what does the middle ear contain?
ossicles and an air filled cavity
where is the air filled cavity of the middle ear situated?
between the tympanic membrane and the inner ear
what does the air filled cavity within the middle ear contain?
ossicles
what is the function of ossicles within the middle ear?
AMPLIFY vibration from the tympanic membrane (external ear order) to the cochlea via the oval window (inner ear opening)
(transmitting sound from middle to inner ear)
what are the ossicles contained within the middle ear?
malleus
incus
stapes
where do sound waves begin transmission? to?
pinna and ear canal transmit sound waves to the tympanic membrane, sound waves make tympanic membrane vibrate (vibrating ossicles up to 20x)
which ossicle (middle ear) attaches to the tympanic membrane (external ear)?
malleus attaches to tympanic membrane
what is significant about the ossicles?
smallest bones of the body
which ossicle attaches to the inner near?
stapes attaches to the oval window (of cochlea)
What is Cochlea full of?
fluid
why ossicles have to vibrate far harder - to send vibrations through fluid of cochlear of inner ear
what is the function of the oval window of cochlea? (attached to stapes)
It allows fluid in the cochlea to move, which in turn ensures that hair cells of the basilar membrane will be stimulated and that audition will occur
what is pressure within the middle ear equalised by?
by the eustachian (pharyngotympanic) tube to the same as atmospheric pressure
(lateral nasopharynx - upper resp infection - otitis media, perforate TM)
where is the middle ear?
behind the tympanic membrane
air filled cavity WITHIN petrous part of temporal bone
what is above the 3 ossicles within the middle ear?
epitympanic recess
aside from pressure equilibration, what is another function of the eustachian (pharyngotympanic) tube?
ventilation and drainage of mucus from middle ear