Sensory Systems - Ear Flashcards
(54 cards)
what is the auricle?
irregularly shaped internal plate of elastic cartilage
-thin skin w/ hair and sebaceous glands
describe lining of external auditory meatus
thin skin - also lines outer surface of ear drum
- has large sebaceous glands
- has coiled tubuloalveolar ceruminous glands
what is ear wax?
mixture of ceruminous and sebaceous secretions + desquamated meatal cells
tympanic cavity: what is in it and what does it connect?
- houses ossicles
- connected to pharynx by eustachian tube
lining of tympanic cavity
simple squamous epithelium that changes to pseudostratified ciliated columnar near the opening to the auditory tube
what are the oval and round windows?
small, membrane-covered regions devoid of bone that separate the middle ear from the bony labyrinth of the inner ear
what are the three ossicles?
malleus, incus, stapes
function of the ossicles
transmits tympanic membrane movements to oval window
describe the inner ear
a fluid-filled membranous labyrinth within a bony labyrinth
endolymph vs. perilymph
endolymph = fluid inside membranous labyrinth (like intracellular fluid, w/ low Na+, protein and high K+) perilymph = fluid outside membranous labyrinth (like ECF, but low protein)
what do the semicircular canals contain?
semicircular ducts of membranous labyrinth
what is contained by the vestibule?
contains perilymph and houses saccule and utricle (which have endolymph)
describe the cochlea
winds 2.5x around modiolus and subdivided into 3 spaces:
- scala vestibuli (filled w/ perilymph)
- scala tympani (filled w/ perilymph)
- scala media (cochlear duct)
what is the modiolus?
bony core of cochlea that has blood vessels and spiral ganglion
what do the lateral extensions of the modiolus form?
osseous spiral lamina
what is the thickened periosteum around the cochlea?
spiral ligament
where are the saccule and utricle found?
inside the vestibule
what are the saccule and utricle and what is their lining?
sac-like bodies of CT lined by simple squamous epithelium that each give off a duct
where do the ducts of the saccule and utricle end up?
they join to form the endolymphatic sac
what do the saccule and utricle contain?
maculae - specialized regions that have 2 types of neuroepithelial hair cells
in general, what are vestibular hair cells?
neuroepithelial cells that have 50-100 rigid stereocilia arranged in rows + a single cilium (kinocilium)
-round, basal nucleus
function of the stereocilia on vestibular hair cells
sensory microvilli
describe location of vestibular hair cell cilia
extend from apical surface of hair cells to an overlying gelatinous layer (otolithic membrane)
describe type I hair cells
- bulbar shape w/ round nucleus
- surrounded by cup-shaped afferent nerve ending