The ear Flashcards
What are the three components of the outer ear
Auricle, External auditory meatus, Tympantic membrane
What is the structure of the auricle
integument overlying elastic cartilage
- integument is thin, keratinized stratified squamous epithelium
- Hair follicles can be observed in the dermis
The auricle is the
pinna of the ear
The outer third of the ear canal is composed of
elastic cartilage
The inner two thirds of the ear canal is composed of
bone
The lining of the ear canal is
stratified squamous epithelium with sebaceous glands and ceruminous glands (modified sebaceous glands)
What separates the external auditory meatus form the middle ear
The tympanic membrane
The core of the Tympanic membrane is formed from
Vacularized, innervated CT
The external surface of the tympanic membrane is covered by
thin skin
The internal surface of the tympanic membrane is covered by
simple cuboidal epithelium
The middle ear (tympanic cavity) is composed of
Auditory ossicles: Malleus, Incus, Stapes
Openings: oval window, round window
Muscles: Tensor tympani, Stapedius
____ attaches to the internal surface of the tympanic membrane
Malleus
The malleus articulates with the
Incus (anvil)
What is the intermediate bone between the stapes and malleus
Incus (anvil)
What is the third auditory ossicle in the series
Stapes
Why is the stapes shaped like a stirrup
due to the opening for the stapedial artery
The stapes inserts onto the
oval window
The oval window opens into the
scala vestibuli
The round window is a membrane covered region at the end of the
scala tympani
Where does the tensor tympani insert
on the malleus
Where does the stapedius insert
on the stapes
What is the purpose of the tensor tympani and stapedius
These muscles contract reflexively in response to loud sounds in order to dampen the vibrations of the auditory ossicles
The inner ear consists of what regions
Bony labyrinth
membranous labyrinth
Vestibular organ
Auditory organ
Complex system of canals and chambers embedded in the petrous portion of the temporal bone
Bony labyrinth
The bony labyrinth is filled with
High-sodium content perilymph
The bony labyrinth consists of
semicircular canals
cochlea
Scala Vestibuli
Scala Tympani
The membranous labyrinth is a
complex system of membranous structures embedded within the chambers of the bony labyrinth
The membranous labyrinth is filled with
high-potassium content endolymp
Endolymph is high in
potassium content
Perilymph is high in
Sodium content
Patches of sensory structures that respond to changes in position
Vestibular organs
The vestibular organs consist of
Maculae of the saccule and utricle
cristae ampullaris of the semicircular canals
Epithelium of the Maculae of Saccule and Utricle
- Columnar supporting cells
- Vestibular hair cells
- Numerous stereocilia
- Single kinocilium
Vestibular hair cells are in contact with
afferent nerve endings
The otolithic membrane is a characteristic of
Maculae of Saccule and Utricle
Gelatinous layer containing calcium carbonate crystals called otoliths that overlie the epithelium
Otolithic membrane
Components of the membranous labyrinth
Utricle
Saccule
Ampullae, which contains the crista ampullaris
Semicircular ducts (which open into the utricle)
Cochlea
Sterocilia of the vestibular hair cells of the Saccule and Utricle are embedded in
The otolithic membrane
Movements of the hair cells displaces the otolithic membrane and causes
a sensory impulse
Important characteristics of the cristae ampullares of semicircular ducts epithelium
Columnar supporting cells
Hair cells
What is the Cupula
It is a gelatinous layer overlying the epithelium of cristae Ampullares (note that it is very similar to otolithic membrane but without ostoliths (calcium carbonate crystals))
Movement of the hair cell in the cupula creates
shear forces between the semicircular canals and the contained fluid
this displaces the cupula and causes the stereocilia to bend
What are the sensory receptors of the membranous labyrinth
cristae ampullares
macula utriculi
macula sacculi
organ of Corti, which is in the Cochlea
what anchors the otolithic membrane to the sensory epithelium
Otogelin
The auditory organ (cochlea) consists of
cochlear duct
Organ of corti
The coclear duct (scala media) consists of
Scala vestibuli Scala tympani vestibular membrane basilar membrane stria vascularis
The coclear duct (scala media) divides the bony cochlea into
scala vestibuli and scala tympani
The vestibular membrane forms the ____ of the cochlear duct
roof
The basilar membrane forms the ____ of the cochlear duct
floor
What forms the lateral aspect of the cochlear duct (scala media)
Stria vascularis
The stria vascularis participates in the formation of the
Endolymph
What lies on the basilar membrane of the cochlear duct
Organ of Corti
The potential difference between the perilymph and the endolymph is
+80 mV
The resting intracellular potential of a hair cell is
-70 mV