Ear Flashcards
describe the development of the inner ear
develops 1st
ectoderm thickens to otic placodes which roll inwards to form otic pit, pinch off and forms otic vesicle.
these form membranous labyrinth
describe the development of the middle ear
forms from outgrowth of 1st pharyngeal throat (endoderm of embryo neck)
what are the regions of the membranous labyrinth
vestibular - for rotation and acceleration
cochlear - hearing
how does the tympanic membrane (eardrum) form
touching of endoderm pouch and ectoderm groove
what do ear bones form from
neural crest cells
what are the elements in the outer ear
Pinna
Ear Canal
Ear Drum
what is the function of the pinna
collects sound to transfer to middle ear
how is the pinna innervated
facial nerve
how does the pinna move and why
auricular muscles
for sound location and communication
how is the pinna involved in thermoregulation
heat radiated off
what produce cerumen (ear wax)
sebaceous and ceruminous glands
whar are ceruminous glands
highly modified apocrine sweat glands
which ossicle is attached to the tympanic membrane
malleus
how are soundwaves sent to the middle ear
cause vibrations of the membrane - move through ossicles
where is the middle ear found in the cranium
temporal bone (in temporal bulla)
what is the function of the auditory tube
allow middle ear to communicate with pharynx
for pressure equalisation and gland secretions
what is the function of the guttural pouch (in equids)
blood cooling due to high vascularisation (ex: carotid artery)
name the 3 ossicles (ear bones)
malleus
incus
stapes
what are the functions of the ossicles
transmit and amplify or decrease vibrations
what is the cavity within the temporal bone
osseous labyrinth
name the regions of the cochlea
inner cochlear duct
middle scala vestibuli
outer scala tympani
how do vibrations move throughout the cochlear for hearing
cochlear duct vibrates which vibrate hair cells
these generate neural impulse which gets carried through cochlear nerve
what are the function of semicurcular canals
detect rotations
(pitch, roll, yaw)
how is rotation detected
movement of endolymph throughout semicircular canals
