Inner Ear Flashcards
what are the two main functions of the inner ear?
- convert mechanical signals from the middle ear into electrical signals
- maintain balance by detecting position and motion
where is the middle ear located?
petrous part of the temporal bone
what are the two main components of the middle ear?
- bony labryinth
- membranous labyrinth
where do the bony labyrinth and the membranous layrinth of the inner ear lie?
bony - petrous part of temporal bone
membranous - within bony
the structures of the bony labyrinth of the inner ear are lined internally with what? what fluid do they contain?
lined with periosteum
contain a fluid called perilymph
what fluid is the membranous labyrinth of the inner ear lined with?
endolymph
the inner ear has two openings into the middle ear - what are these?
oval window - between middle ear and vestibule
round window - between middle ear and scala tympani
the bony labyrinth consists of what three parts?
cochlea
vestibule
semi-circular canasl
the cochlea, vestibule and semi-circular canals are all part of what ear structure?
the bony labyrinth of the inner ear
the vestibule is separated from the middle ear by what?
oval window
what parts of the membranous labyrinth are located within the vestibule?
saccule and utricle
what part of the membranous labyrinth is located within the cochlea?
cochlea duct - auditory part of inner ear
the cochlea twists around a central portion of bone, forming a seashell shape - what is this bone called?
modiolus
what bone extends out from the modiolus and ataches to the cochlear duct?
spiral lamina
what chamber lies superiorly to the cochlear duct?
scala vestibuli
what chamber lies inferiorly to the cochlear duct?
scala tympani
the scala vestibuli and scala tympani are two chambers above and below the cochlear duct - what are they each filled with?
perilymph
how many semi-circular canals are there in the bony labyrinth?
3 - anterior, lateral, posterior
the semi-circular canals contain what? what are these important for?
contain semi-circular ducts, which are responsible for balance (alongside the utricle and saccule)
the membranous labyrinth is a continuous system filled with what?
endolymph
what 4 things is the membranous labyrinth composed of?
cochlear duct, 3 semi-circular ducts, saccule, utricle
which of the following are organs of hearing, and which are organs of balance?
* semi-circular ducts
* cochlear duct
* saccule
* utricle
- semi-circular ducts - balance
- cochlear duct - hearing
- saccule - balance
- utricle - balance
what are the following walls of the cochlear duct called?
* lateral wall?
* roof?
* floor?
- lateral wall - spiral ligament
- roof - Reissner’s membrane
- floor - basilar membrane
what does the basilar membrane of the cochlear duct hold?
the Organ of Corti - epithelial cells of hearing
which is larger - saccule or utricle?
utricle
how does endolymph drain in the membranous labyrinth of the inner ear?
- drains from saccule and utricle into endolymphatic duct
- duct travels through vestibular aqueduce to posterior aspect of petrous part of temporal bone
- duct expands to a sac - endolymph is secreted and absorbed
how do the semi-circular ducts help balance?
- head moves
- endolymph within ducts changes speed and/or direction
- sensory receptors in ampullae of canals detect this change
- sends signals to brain about processing balance
the bony labyrinth receives blood supply from what arteries?
- anterior tympanic branch
- petrosal branch
- stylomastoid branch
the membranous labyrinth is supplied by what artery?
labyrinthine artery
the labyrinthine artery divides into what 3 branches?
cochlear branch
vestibular branches x2
how does venous drainage of the inner ear occur?
labyrinthine vein
what innervates the inner ear?
vestibulocochlear nerve (CN VIII)
CN VIII (vestibulocochlear nerve) divides into what?
vestibular nerve - balance
cochlear nerve - hearing
Label the parts of the ear
Label the membranous labyrinth
Label the cochlear
label the bony labyrinth
