Audition Flashcards
List the structures that makeup the outer ear
- pinna
- external auditory canal
- tympanic membrane (eardrum)
List the structures that makeup the middle ear
ossicles (malleus -> incus -> stapes)
List the structures that makeup the inner ear
- oval window of cochlea
- cochlea
- semicircular canal
List the structures of the hearing pathway from outer ear to brain
- pinna
- external auditory cortex
- tympanic membrane
- malleus
- incus
- stapes
- oval window
- perilymph in cochlea
- basilar membrane
- hair cells
- vestibulocochlear nerve
- brainstem
- medial geniculate nucleus of thalamus
- auditory cortex in temporal lobe
What is the range (in Hz) that humans hear sounds?
20-20,000 Hz
What is the main function of the pinna?
channel sound waves into the external auditory canal
Where are sound waves directed to from the external auditory canal?
tympanic membrane
Tympanic Membrane
- eardrum
- divides the outer ear from the middle ear
- vibrates in phase with the incoming sound waves
- frequency of sound wave determines the rate at which this membrane vibrates: moves back and forth at high rate for high frequency sounds and slowly for low frequency sounds
- louder sounds have greater intensity – increased amplitude of vibration
Ossicles
- the three smallest bones in the ear (and body)
- help transmit and amplify the vibrations from the tympanic membrane to the inner ear
- malleus is affixed to tympanic membrane and acts on the incus which acts on the stapes (baseplate of this bone rests on the oval window of the cochlea)
Eustachian Tube
- connects the middle ear to the nasal cavity
- helps equalize pressure between the middle ear and the environment
Bony Labyrinth
- what the inner ear sits within
- contains the cochlea, vestibule, and semicircular canals
What fills the structures in the bony labyrinth?
membranous labyrinth
Membranous Labyrinth
- bathed in K+ fluid called endolymph
- suspended within the bony labyrinth by a thin layer of another fluid called perilymph
Perilymph
- simultaneously transmits vibrations from the outside world
- cushions the inner ear structures
Cochlea
-spiral-shaped organ divided into 3 parts called scalae