Lec 20 The Ear & Eye Flashcards
What is the purpose of the tympanic membrane? (eardrum)
separates outer ear from middle ear
what 3 layers is the tympanic membrane composed of?
outer - modified skin
middle - fibrous layer
inner - mucous layer
pulled posteriorly & superiorly; translucent enough to see mallelus attached to inner surface.
These are qualities of the.. ?
tympanic membrane
what is the middle ear composed of?
tympanic cavity
auditory (eustachian tube)
ossicles
what is the eustachian tube?
where middle ear is connected to the nasopharynx.
horizontal in child but slowly becomes more vertical in adult. (which is why in a child, bacteria can easily travel from naso to middle ear)
what are 3 forms of ossicles?
mallelus - attached to tympanic membrane
incus - interposed between mallelus and stapes
stapes - inserted into oval window of inner ear
where is the inner ear located?
temporal bone
where are receptors for hearing and equilibrium located?
special structures in the inner ear
what parts do the inner ear divide into?
cochlea, vestibule, and semicircular canals
what is equilibrium also influenced by, other than the vestibular apparatus?
impulses from the spinal cord and cerebellum.
information coming from visual stimuli and receptors of muscles and tendons.
what is the structure of a cochlea?
connection of tubes and sacs
What does the vestibular apparatus sense?
equilibrium. hair creates electrical impulse.
what is the difference between endolymph and perilymph?
endolymph = internal fluids in membranous labyrinth.
perilymph = “surrounding water”. fluid in bony labyrinth.
which structures make up the inner ear?
cochlea
vestibule
semicircular canals
what are the organ of Corti?
Hair cells, receptor epithelium for hearing
what is the purpose of the vestibulocochlear nerve? (CNVIII)
transmits impulses from hearing and equilibrium receptors to appropriate areas of the brain for interpretation
what is the auditory pathway?
cochlear division of CN VIII -> nucleus of VIII in medulla -> thalamus -> auditory cortex of temporal lobe.
what is the conjuctiva?
a transparent mucous membrane that covers the inner surfaces of the eyelids
what is the lacrimal gland?
produces lacrimal fluid. Blinking spreads this fluid across the eyeball
what is the sclera?
“the white of the eye”
protects eyeball and provides shape and anchoring for eye muscles.
what is the iris?
colored part of eye
what is the retina?
inner layer that contains pigmented layer and thick neutral layer.
what is the aqueous humor?
(aqueous = watery)
clear fluid similar to blood plasma.
renewed constantly, is in constant motion.
what is the vitreous humor?
(vitreus = glassy)
jellylike substance that contains collagen and ground substance that binds water
