Special Senses Ear Flashcards
what makes up the tympanic membrane?
- external surface
- thin skin
- collagen fibers
- simple squamous epithelium
- inner surface
what is the function of the tympanic membrane?
transmit vibrations of sound pressure waves to the middle ear bones
what makes up the middle ear?
-ossicles
malleus
incus
stapes
-windows
oval window
round window
in what bone is the inner ear located?
pertrous part of temporal bone
what makes up the bony labyrinthe of the inner ear?
- 3 semicircular canals
- vestibule
- cochlea —2.5 turns
what makes up the membraneous labyrinth of the inner ear?
- semicircular ducts
- vestibular labyrinth/duct
- cochlear labyrinth/duct
what does the membranous labyrinth contain?
series of communicating sacs and ducts containing endolymph!
the other spaces that remain contain perilymph
where is the membranous labyrinth located?
suspended within bony labyrinth!
what are the subdivisions of the membranous labyrinth?
-vestibular labyrinth semicircular duct utricle saccule -cochlear labyrinth cochlear duct
where is perilymph located?
in the body labyrinth
what is perilymph composed of?
resembles ECF and CSF - high Na+ and low K+
where is endolymph located?
fluid in the membraneous labyrinth
what is the composition of endolymph?
similar to ICF - low Na+ and high K+
how are the semicircular canals attached to the vestibule
expaned ampulla
what is the vestibule?
- large central cavity
- contains oval and round windows on lateral wall that leads into cochlear canal
- reps bony labyrinth
- contains membranous laby - utricle and saccule
what are the cells of the membranous labyrinth?
sensory hair cells
supporting cells
what are the endolymph space that sensory hair cells project into?
3 cristae ampullaris - ampullary crests of semicircular ducts 2 maculae utricle - macula of utricle saccule - macula of saccule spiral organ of Corti - sound receptor
what characteristics do hair cells have?
sterocilia that contain actin filaments DUHHH
hair bundle - rows of stereo cilia
kinocilium - contains microtubules - actually move!
what generates nerve impulses?
deflection of stereocilia during angular acceleration of the head
where is the macula contained?
within the utricle and saccule
what are maculae?
sensors of gravity and linear acceleration of the head
what is the otolithic membrane (OM)?
gelatinous polysaccharide material over the epithelium in maculae
what is the otoconia?
the outer aspect of OM crystalline bodies of calcium carbonate and protein on maculae
stabilizes the jelly like structure
what does the cochlea contain?
cochlear duct (scala media)
what does the cochlea make 2.5 turns around?
modiolus
what is the thin body ridge that extends laterally from the modiolus?
spiral lamina
what is found in scala vestibuli and scala tympani?
perilymph
what is found in scala media?
endolymph
what separates the scala vestibuli from the scala media/cochlear duct?
Reissner’s membrane/vestibular membrane
what separates the cochlear duct/scala media from the scala tympani?
basilar membrane
how do the two scala (tympani and vestibule) which is one long tube, communicate ?
helicotrema - small opening at apex of cochlea
what are the histological features of cochlear duct?
- vestibular membrane/Reissner’s
- stria vascularis - resposible for ionic comp of endolymph
- organ of corti - contains neuroepithelial hair cells that rest on basilar membrane
what are characteristics of the organ or corti?
stereocilia
pillar cells
what do high frequency sounds cause?
max. displacemnt of basilar membrane and the base of cochlea - vibrates
what does low frequency sounds cause?
apex of cochlea - vibration
