ear Flashcards
temporal bone is composed of what 3 portions
- squamous: contains zygomatic process and mandibular fossa
- Tympanic: middle ear cavity and external acoustic meatus
- Petrous: mastoid and styloid process
The inferior portion of the petrous portion of the temporal bone contains what foramen/canal?
- stylomastoid foramen
- carotid canal
- jugular foramen (part)
Inner ear is filled with what? What is its function?
- inner ear is fluid filled space within petrous portion of the temporal bone
- hearing and balance
What is the middle ear filled with? What is its function?
- middle ear is an air filled space within the petrous and tympanic portions of the temporal bone
- hearing
What is the function of the external ear
- external ear emerges from tympanic part of temporal bone
- hearing
What is the space between the membranous and bony labyrinths of the inner ear
perilymph space
Name the 2 sections of the labyrinth. What is their innervation?
- vestibule
- cochlea
- both innervated by CN VIII
vestibule of inner ear
contains all organs of balance and orientation
cochlea of inner ear
contains the organ of hearing
function of hair cells of inner ear
specialized sensory cells that alter the rate they stimulate an associated sensory nerve in response to bending of hair-like projections
differentiate between kinocilium and sterocilia
- kinocilium: tallest single projection out of apex of hair cell
- stereocillia: array of progressively shorter projections lined up next to the kinocilium
* rate of signals from hair cells depends on the direction of the stereocilis bending relative to kinocilium
Name the 2 different types of balance organs located in the vestibule of the inner ear
- maculae
- cristae
describe the function of maculae of inner ear. Name the 2 maculae
- sheets of hair cells stimulated by linear accelerations
- horizontal macula: located on utricle
- vertical macula: located in the saccule
- Describe function of cristae of inner ear
- Where are they located
- crests of hair cells stimulated by fluid flow around the semicircular ducts in response to rotation
- each 1 of the 3 semicircular ducts has a crista located in the ampulla at one end
Hair cells in the cochlea are arranged in one long ribon that runs the full length of what?
spiral shaped Cochlear duct
What organ in the inner ear is stimulated by sound waves transmitted from the surrounding perilymph into the endolymph of the cochlear duct
organ of corti
The vestibulocochlaer nerve passes into what hole? What 2 main branches does it divide into?
- internal acoustic meatus
- cochlear branch: hearing
- vestibular branch: balance
The facial nerve passes into the internal acoustic meatus with the vestibulocochlear n.
- What ganglion does it travel to?
- what branch does it give off from the ganglion?
- facial nerve travels between the cochlea and vestibular organs to reach the geniculate ganglion
- greater petrosal nerve: heads to middle cranial fossa
- facial nerve continues in bone between inner and middle ear spaces
Through what 2 passageways does the inner ear connect to the middle ear cavity
- oval window
- round window
Name the three middle ear bones from most external to most internal
- Malleus
- Incus
- Stapes
The stapes is connected to what?
oval window
bony bulge in middle ear caused by first coil of cochlea is what
promontory
What nerve plexus lies in the middle ear? What nerves come to and from plexus
- tympanic plexus
- Tympanic nerve from CN IX
- lesser petrosal nerve
What the function of the stapedius muscle? What nerve is it innervated by
- dampens vibration of the stapes in reaction to potentially damaging loud sounds
- facial nerve (CN VII)
Where does the chorda tympani emerge from the facial nerve? Where does the facial nerve travel once it gives off chorda tympani
- emerges from posterior wall adjacent to lateral wall of middle ear cavity
- facial nerve continues in posterior wall to exit the stylomastoid foramen
Chorda tympani passes between what 2 bones in middle ear
crosses tympanic membrane between malleus and incus
Origin, insertion, and innervation and action of tensor tympani
- origin: small canal superior to pharyngotympanic tube
- insertion: body of malleus inferior to chorda tympani
- innervation: branch of mandibular nerve (CN V3)
- action: dampen sound: perhaps from own voice
What tube arrises from the middle ear and is a passage way between pharynx and tympanic cavity? What is its function
- pharyngotympanic tube
- allow pressure equalization
- composed of bone and cartilage: cartilage passively closes tube; muscle activity required to open tube
What two muscles are responsible for opening up the pharyngotympanic tube?
Levator veli palatine: innervated vagus
tensor veli palatine: innervated CN V3
Why are young children more likely to get otitis media
in young children, the pharyngotympanic tube has a more horizontal orientation
- more likely for infectious materal from respiratory or GI tracts to pass into the middle ear cavity
NAme the identifiable parts of the tympanic membrane
- flaccid part
- tense part
- umbo
- cone of light: reflected from otoscope
If otitis media is causing bulging of the tympanic membrane; what will be distored
the cone of light
red and black
red: tragus
black: antitragus
green and blue
green: helix
blue: antihelix
The external ear has extensive innervation. Name the nerves responsible
cervical plexus
- Lesser occipital
- Great auricular
Cranial nerves
- auriculotemporal nerve (CN V3)
- facial nerve
- auricular branch of vagus
