Chapter 15.7 Ear Anatomy Flashcards
Shell shaped structure surrounding external acoustic meatus
Composed of elastic cartilage covered with thin skin
Function: funnels sound waves into auditory canal
Auricle
Cartilaginous rim in auricle
Helix
Fleshy earlobe of auricle
Lobule
Short, curved tube; Lined with skin bearing hairs, sebaceous glands, and ceruminous (earwax) glands
Transmits sound waves to eardrum
External acoustic meatus (auditory canal)
Boundary between external and middle ears; Thin, translucent connective tissue membrane
A.k.a eardrum
Vibrates in response to sound
Transfers sound energy to bones of middle ear
Tympanic membrane
Small, air-filled mucosa-lined cavity in temporal bone
Flanked laterally by eardrum and medially by bony wall
Bony wall contains: oval, round membranous windows
Middle ear
If _____ is not equal on both sides of tympanic membrane, sounds are distorted
Pressure
Connects middle ear to nasopharynx, equalizes pressure in middle ear with external air pressure
Formerly called eustachian tube
Usually flattened tube, but can be opened by yawning or swallowing to equalize pressure
Pharyngotympanic tube
Three small bones in tympanic cavity, named for shape
Bones: Malleus, Incus, Stapes
Transmit vibratory motion of eardrum to oval window
Auditory ossicles
The ‘hammer’ is secured to eardrum
Malleus
The ‘anvil’ portion, in the middle
Incus
The “stirrup” base fits into oval window
Most interior bone
Stapes
Muscle that contracts reflexively in response to loud sounds to limit ossicle vibration and limit damage to hearing receptors
Tensor tympani
Middle ear inflammation
Commonly seen in children with sore throat
Most frequent cause of hearing loss in children
Acute infectious forms cause eardrum to bulge outward and become inflamed
Otitis media
A.k.a labyrinth
Located in temporal bone behind eye socket
2 divisions: bony labyrinth, membranous labyrinth
Inner ear
System of bony channels and cavities in the temporal bone
3 regions: vestibule, semicircular canals, cochlea
Filled with perilymph fluid (similar to CSF)
Bony labyrinth