What is found in the petrous part of the temporal bone? (2)
2. internal acoustic meatus
What type of energy does the external ear transmit?
sound waves
What type of energy change occurs in the middle ear? (2)
Sound waves to mechanical
What type of energy change occurs in the inner ear? (2)
mechanical to electrical
What cranial nerves run through the internal acoustic meatus?
vesitbulocochlear nerve (CN VIII)
facial nerve (CN VII)
What is the petrous part of the temporal bone like?
very hard
What is the ear drum known as?
tympanic membrane
What does the auditory tube do?
Connects to nasopharynx
enables air passage to maintain equilibrium of pressure
Why is the middle ear a high risk space? (5)
What also increases infection risk especially concerning nerves?
holes which nerves pass through
What is the inner ear?
series of fluid filled cavities
In the inner ear, what are the names of the series of cavities the petrous part of the temporal bone have and what do they contain?
perilymph
Where does the cochlear duct run through and what type of lymph does it contain?
runs through the cochlea
contains endolymph
What is the cochlear duct?
a membranous sac (closed tube) contain endolymph
What is the ion conc like in endolymph?
low sodium
high potassium
Things you need to know in inner ear? (5)
What type of lymph does the cochlea contain?
perilymph
What two chambers does the cochlear duct separate the cochlea into?
2. scala tympani
What are the two chambers scala vestibuli and tympani continuous of?
apex of cochlea - helicotrema
How is sound transmitted in the cochlea?
What makes up the roof and floor of the cochlear duct?
roof - vestibular membrane
floor - basement membrane
What is the auditory receptor?
The spiral organ (of Corti) on the basilar membrane
What does the spiral organ contain?
hair cells with the tips embedded into the tectorial membrane
What is the spiral organ stimulated by?
the deformation of the cochlear duct by perilymph in the surrounding Scala vestibuli and scala tympani