Anatomy of the Auditory System Flashcards
Outer ear
Pinna
External auditory canal
Pinna
Cartilage covered with skin
Conducts sound to the middle ear
Aids in localization and sound collection
External auditory canal
First third is cartilaginous, second third is osseous
Conducts sound to the tympanic membrane
Protects TM from trauma
Sebaceous glands secrete cerumen
Middle ear
Tympanic membrane
Ossicles
Eustachian tube
Muscles
Tympanic membrane
Concave disklike structure
3 layers
Cone of light
Converts acoustic energy into mechanical energy
Ossicles
Malleus, incus, stapes
Malleus connects to TM
Stapes connects to oval window
Conducts sound from TM to inner ear
Eustachian tube
Tube in the posterior-inferior portion of the ME space
Leads to nasopharynx
Maintains equal pressure between the ME and atmosphere
Opens periodically through jaw movement
Middle ear muscles
Stapedius
Tensor Tympani
Stapedius
Attaches to the neck of the stapes
Contract to loud sounds
Tensor tympani
Attaches to the manubrium of the malleus
Contracts in response to non-auditory stimulation
Inner ear
Oval window
Vestibule
Round window
Cochlea
Oval window
Separates the inner ear from the middle ear
Vestibule
The immediate entryway into the inner ear
Round window
Opening that vibrates opposite in phase from vibrations entering the cochlea via the oval window
Cochlea
A snail-shaped, fluid-filled space with 2.5 turns, 35 mm in length
3 fluid filled chambers: scala vestiboli, scala tympani, scala media
Basilar membrane
Membrane in the cochlea that the basilar membrane sits on
Tonotopic organization
Auditory nerve fibers response are frequency specific
Base of cochlea responds to high frequencies
Mid to apex of cochlea responds to low frequency sounds
Scala media
Lies between the Scala vestibule and tympani, sectioned by 2 membranes
Organ of corti
Organ of corti
Sits on basilar membrane
Contains the sensory cells of hearing
Tectorial membrane
Covers the organ of corti
Tips of the outer hair cell stereo cilia are embedded in it
Inner hair cells vs outer hair cells
Inner hair cells have 1 row, 3,000 total
Outer hair cells have 3 parallel rows, 12,000-15,000 total
Motion of fluid within the utricle and saccule
Linear acceleration
Ex: elevator moving, car changing speed
Motion of fluid in the semicircular canals
Angular acceleration
Ex: changes in head/body position
Basic pathway of hearing
Enter ear, sound/vibration from middle ear, traveling wave in cochlear partition, basilar membrane moves, hair cells shear, cilia of hair cells bend, chemical/mechanical release, action potential of auditory nerve
Final destination for speech information processing
Temporal lobes
Outer ear disorders (pinna)
Microtia
Anotia
Cauliflower ear
Malignant tumors
Atresia
Outer ear disorders (ear canal)
Collapsing ear canal
Foreign bodies
External otitis
Necrotizing/malignant external otitis
Growths
Cerumen
Injuries
Middle ear disorders
Perforations of the TM
Otitis media
Cholesteatoma
Otosclerosis
Ossicular chain discontinuity
Eustachian tube dysfunction
Barotrauma
