Ch 14: Hearing Flashcards
what is the functional component of CN 8?
SSA
sound consists of ?
sinusoidal waves- alternating condensations and rarefactions- of air molecules
the frequency of the waves is measured in?
frequency determines?
measured in Hz
determines pitch of the sound
the amplitude of each wave is measured in?
amplitude relates to?
measured in decibels (dB)
relates to the loudness of the sound
the human ear can detect sound frequencies from ____ and loudness from _____?
frequencies: 20 - 20,000 Hz
loudness: 1 - 120 dB
what are the 3 components of the auditory apparatus?
external ear
middle ear
inner ear
these components occupy 3 spaces in the skull, separated solely by membranes
what does the external ear (auricle) lead to?
the external auditory meatus
what separates the external auditory meatus from the cavity of the middle ear?
the tympanic membrane
what are the 3 ossicles that span the middle ear?
malleus
incus
stapus
what does the malleus attach to?
the tympanic membrane
what does the stapes attach to?
the oval window through a ligamentous membrane on its footplate
what does the oval window do?
separates the air filled middle ear cavity from the fluid filled inner ear cavity
provides an opening into the vestibule portion of the inner ear which contains perilymph
what happened when sound mediated by air strikes the tympanic membrane?
it induces motions in this membrane that the ossicles convey to the oval window
the chain of these 3 ossicles in the middle ear serves as an amplifier as well as an impedance-matching device that decreases the amount of energy lost by the sound waves in going from air to the fluid (perilymph) behind the oval window
what is continuous on either side of the vestibule of the inner ear?
vestibule consists of a chamber that is continuous on one side with the cochlea and on the other side with the semicircular canals
what is the cochlea?
a perilymph-containing tube
resembles a snail shell
about 3.5 cm long wrapped around itself in 2.5 turns
the cochlea, semicircular canals and the vestibule make up the:
what lies within it?
these 2 connected chambers within the temporal bone of the skull make up the bony labyrinth
a membranous labyrinth lies within the bony and contains endolymph
what is the modiolus?
a conical central bony core that forms the axis of the cochlear turns
what is the spiral lamina?
a ridge of bone turning around the moidolus, projects into the cochlear space
partially divides the cochlear cavity into two perilymphatic chambers
what are the 2 perilymphatic chambers?
1- scala vestibuli
2- scala tympani
what is the scala media or cochlear duct?
forms the membranous labyrinth within the cochlea
completes the separation of the scala vestibuli from the scala tympani