Auditory System Flashcards
Major parts of the auricle composed of this
Elastic cartilage, sebaceous glands
Regions of auricle
Helix/ antihelix, tragus/antitragus, concha/lobue
What are the ceruminous glands?
Found in the external acoustic meatus. Aprocrine-type gland.
What is ear wax?
Mixture of cerumen, sebaceous gland secretio, and desquamated meatal cells
Innervation of the tympanic cavity
x
What are the ceruminous glands?
Found in the external acoustic meatus. Aprocrine-type gland. Not to be confused with sebaceous glands- these are associated with the vellus hairs
Innervation of the middle ear
Glossopharyngeal (IX)
Innervation of eterna ear and external acoustic meatus
3- Greater auricular, lesser occipital, auriculotemporal- part of temperomandibular (V3)
Facial (VIII), Vagus (X)
Innervation of the middle ear (tympanic cavity)
Glossopharyngeal (IX)
Difference in pressure between eustatian tube and external meatus may be relieved by this action
swallowing- opens eustatian tube to the pharynx
What muscles open the eustatian tube via the tubal cartilage
Levator palati, Tensor palati, salpingopharyngeus
- air gets to enter the inner ear
- they also pull up the soft palate
Function of ossicles
Amplify sound from vibrations of the tympanic membrane
-Malleus, Incus, Stapes: decrease in surface area
Tensor tympani muscle function
Dampens ossicle movement- low frequency
Sits in eustatian tube and meets up to the handle of the malleus
Stapedius muscle function
Attaches stapes- pulls on stapes when there is extreme vibrations
Chorda tympani- how, where it moves, what source
Goes through temporal bone. Branches from facial nerve (VII) and joins V3
Tensor tympani is innervated by
V3
Stapedius is innervated by
VII- facial
Function of chorda tympani
Sensory- taste from anterior 2/3 of tongue
Parasympathetic- submandibular and sublingual salivary glands
Chorda tympani- how, where it moves, what source
Goes through temporal bone- passes by tympanic membrane, and leaves bone to meet with lingual nerve. Branches from facial nerve (VII) and joins V3
Function of chorda tympani
Sensory- taste from anterior 2/3 of tongue
Parasympathetic- submandibular and sublingual salivary glands
Otitis media
infection affecting chorda tympani, ossicles, tympanic membrane
Otitis media symptoms
Decreased taste and decreased salivation
Otitis media
infection of middle ear affecting chorda tympani, ossicles, tympanic membrane
Negative pressure pulls tympanic membrane into the tympanic cavity
Tegmen tympani
When otitis media infection perforates tympanic membrane- results in meningitis or brain abscess
Otitis media symptoms
Decreased taste and decreased salivation.
Pain by negative pressure moving membrane in (V3)
Tegmen tympani
When otitis media infection perforates tympanic membrane- results in meningitis or brain abscess. This is the area that connects the middle ear to the meninges.
Spaces in cochlea
Scala tympani, cochlear duct, scala vestibuli
Cholesteatoma
Perforation in the tympanic membrane- permits entry of skin cysts. This damages the middle ear and mastoid (can cause eruptions of the air cells in this part of the skull). Cllot of dead cells and sebum
Cochlea is composed of these spaces
Cochlear duct- scala tympani (media), cochlear duct, scala vestibuli
Perilymph vs Endolymph
Perilymph- same as CSF. A filtrate of blood. High K+
Endolymph- fluid inside cochlear duct made by stria vascularis. High Na+
There is a change of electrical potential between the 2 fluids
Perilymph vs Endolymph
Perilymph- same as CSF. A filtrate of blood. High K+
Endolymph- fluid inside cochlear duct made by stria vascularis. High Na+
There is a change of electrical potential between the 2 fluids
This medium stimulates receptor cells
Fluid in cochlea
Order of sound conductance
Ear drum-> malleus, incus, stapes-> oval window-> perilymph of scala vestibuli-> perilymph of scala tympani-> Round window
Order of sound conductance
Ear drum -> malleus, incus, stapes -> oval window- > perilymph of scala vestibuli -> perilymph of scala tympani -> Round window -> auditory tube
Organ of corti cell types, location, tectorial membrane
Basilar membrane, tectorial membrane, receptor hair cells, sensory neurons
Tectorial membrane location
Between Organ of Corti and Endolymph containing portion of cochlear duct
Ear ringing caused by
Malleus tensing tightly to protect ear from heavy vibration. When moved away from low-frequency (dangerous) sounds, you can only hear high and mid frequency since the contraction is still happening
Ear ringing caused by
Malleus tensing tightly to protect ear from heavy vibration. When moved away from low-frequency (dangerous) sounds, you can only hear high and mid frequency since the contraction is still happening
This membrane protects receptor cells of organ of corti
Tectorial membrane
Stereocilia are these and are located here
Microvilli “hair” cells that are located on the basilar membrane and contact the tectorial membrane
Sensory nerve of organ of corti
VIII- vestibulocochlear
How the cochlea encodes sound frequencies
Hair cells move in response to sheer forces on tectorial membrane. This depolarizes receptor cells –> K+ channels open (Endolymph). This releases vesicles to the afferent nerve
Sound waves vibrate the full length of this
Basilar membrane
Tonotopy is the frequency of sound coded by difference of this
Basilar membrane as it widens and ascends- produces complex sound waves
Resonance frequency
The frequency at which the membrane vibrates best
Inner hair cells transmit sound info to
CNS
Inner cells respond to movements from this membrane
Basilar membrane
Signal is transmitted to this part of the brain
Medulla- via the cochlear nuclei
Signal is transmitted to this part of the brain
Medulla- via the cochlear nuclei
Outer hair cells function as this
Mechanical amplifiers
Prestin does this
Moves outer hair cells by the movement of the basilar membrane
Hearing loss is mainly due to the destruction of this
The outer hair cells
Conductive deafness is due to
Damage of the tympanic membrane
Acoustic neroma is this
A tumor of schwann cells (schwannoma)
Subjective tinnitus is
Sensation of sound without external stimulation- a phantom perception
This area of the auditory pathway has abnormal activity
- Dorsal cochlear nucleus- increases spontaneous activity
- Primary auditory cortex
