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 location of the sound wave transfer from the perilymph to endolymph depends on what
the frequency of sound
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

geniculate ganglion contains what type of cell bodies
somatic sensory
taste
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 type of innervation does the tympanic nerve from CN IX carry
presynaptic parasympathetics
somatic sensory to middle ear
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

cartilaginous ear canal contains what glands that produce earwax
ceruminous glands
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
