lecture 33 ear

balance or equilibrium and hearing

what are the two special sensory functions of the ear?

inner ear only

balance and equilibrium is within what part of the ear?

all three

hearing uses structures in what regions of the ear?

pinna, tympanic membrane

the external ear extends from ___ to ___

funnels sound to the tympanic membrane

what does the external ear do?

air-filled tympanic cavity containing 3 auditory ossicles

describe middle ear

fluid filled channels that convert mechanical energy into nerve impulses

describe inner ear

squamous part, tympanic part, mastoid part, petrous part

list the regions of the temporal bone that relate to the ear

squamous part

what part of the temporal bone is flat and smooth like a scale with zygomatic process projecting anteriorly?

tympanic part

what is the bony collar of the temporal bone that helps form the external acoustic meatus?

mastoid part

what part of the temporal bone (that relates to the ear) contains air cells?

petrous part

what part of the temporal bone (that relates to the ear) houses the organs of hearing and equilibrium?

middle and posterior cranial fossae

what does the petrous part of the temporal bone form a portion of?

pinna, external acoustic meatus, tympanic membrane

what are the parts of the external ear?

tympanic membrane

what is the boundary between the external ear and middle ear?

inflammation of the structures of the external ear

what is otitis externa?

Swimmer's ear

what is otitis externa aka?

auricle or pinna

what is the funnel shaped structure that directs sound into the external acoustic meatus?

elastic cartilage covered by skin except for lobule which is fibrous connective tissue and epithelium

what is the auricle/pinna made of?

growth hormone

what hormone is the pinna/auricle affected by throughout life?

avascular

is the pinna/auricle largely vascular or avascular?

outer, posterior convex curve of pinna

what is the helix?

concentric curve parallel to helix

what is the antihelix?

triangular projection of tissue anterior to opening of external acoustic meatus

what is the tragus?

projection from posterior that opposes tragus

what is the antitragus?

earlobe (no elastic cartilage)

what is the lobule?

shell shaped fossa

what is the concha of the pinna/auricle?

deepest part of concha

what is the cymba of the pinna/auricle?

helix, antihelix, tragus, antitragus, lobule, concha, cymba

list the structures of the auricle/pinna

epiglottis, ear, eustachian tube

what are the only 3 places in the entire body to have elastic cartilage?

S-shaped tube that extends ~2.5 cm medially

describe external acoustic meatus

concha, tympanic membrane

the external acoustic meatus runs from the ___ to the ___

tympanic part of temporal bone

what forms the medial 2/3 of the external acoustic meatus?

cartilaginous and lined by skin with sebaceous and ceruminous glands and hair follicles

describe the lateral 1/3 of the external acoustic meatus

thin, semitransparent, oval membrane

what are the features of the tympanic membrane?

a mucous membrane

the internal lining of the tympanic membrane is what?

skin

the external lining of the tympanic membrane is what?

transmits vibrations via auditory ossicles

how does the tympanic membrane transmit sound waves to internal ear?

auditory ossicles

what structures are responsible for amplification of sound in the ears?

5 o'clock

using clock analogy, where is the cone of light on the right?

7 o'clock

using clock analogy, where is the cone of light on the left?

air-filled, narrow box with 6 sides

describe tympanic cavity

1.5 cm high x 1.5 cm deep x 0.5 cm wide

what are the dimensions of the tympanic cavity?

mucous membrane

what is the tympanic cavity lined with?

auditory tube, mastoid air cells

the tympanic cavity opens into the ___ and is connected to the ___

tegmen tympani ("covering" of the tympanic cavity)

what is the roof of the tympanic cavity?

thin plate of bone separating the tympanic cavity from the middle cranial fossa

what is the tegmen tympani?

tegmen tympani

otitis media can spread through what bone to reach the meninges?

jugular wall

what is the floor of the tympanic cavity?

bony septum between the tympanic cavity and internal jugular v

what is the jugular wall?

tympanic membrane and membranous wall

what is the lateral wall of the tympanic cavity composed of?

labyrinthine wall

what is the medial wall of the tympanic cavity aka?

medial wall of tympanic cavity (labyrinthine wall)

what separates the middle ear from inner ear?

membranous labyrinth, ducts of inner ear

what does the medial wall (labyrinthine wall) refer to?

raised area opposite the TM that is covered by tympanic plexus

what is the promontory?

promontory, fenestra vestibuli, fenestra cochleae

what does the medial wall (labyrinthine wall) of tympanic cavity contain?

fenestra vestibuli

what is the name for the oval window?

footplate of the stapes

the ___ fits over the fenestra vestibuli membrane

fenestra cochleae

what is the name for the round window?

membrane-bound opening between middle ear and cochlea (round window)

what is the fenestra cochleae?

mastoid wall

what is the posterior wall of the tympanic cavity aka?

aditus to mastoid antrum, pyramidal eminence, opening for chorda tympani n

what does the posterior wall (mastoid wall) of the tympanic cavity contain?

opening to mastoid air cells

what is the aditus to the mastoid antrum?

conical elevation through which the tendon of the stapedius m passes through

what is the pyramidal eminence?

lateral to the pyramidal eminence

where is the opening of the chorda tympani n located?

carotid wall

what is the anterior wall of the tympanic cavity aka?

thin body plate that separates the carotid artery from the tympanic cavity

what is the anterior wall (carotid wall) of the tympanic cavity?

superior opening in anterior wall (carotid wall) of tympanic cavity

where does the tensor tympani m pass through?

inferior opening on anterior wall (carotid wall) of tympanic cavity

where is the pharyngeal opening to the auditory tube located?

roof, floor (jugular wall), lateral wall, medial wall (labyrinthine wall), posterior wall (mastoid wall), anterior wall (carotid wall)

what are the sides of the tympanic cavity?

auditory ossicles, stapedius m, tensor tympani m, chorda tympani m, tympanic plexus

list contents of tympanic cavity

auditory ossicles

what transmits vibrations from tympanic membrane to the inner ear?

base of the stapes has smaller surface area than the TM

what causes the auditory ossicles amplify the force of vibrations to inner ear?

hammer, connected to TM

what is the malleus?

anvil, transmits vibrations from malleus to stapes

what is the incus?

stirrup, footplate connected to oval window

what is the stapes?

between incus and stapes, incudostapedial joint

where is the smallest bone and socket joint located?

facial n

what is the chorda tympani n a branch of?

lingual branch of mandibular n

what does the chorda tympani n join?

chorda tympani n

what n conveys taste from anterior 2/3 of tongue?

submandibular and sublingual salivary glands

what does the chorda tympani n carry parasympathetic fibers to?

branches of CNs VII and IX

what is the tympanic plexus formed by?

mucosa of middle ear, mastoid cells, and auditory tube

what does the tympanic plexus supply?

eustachian tube and pharyngotympanic tube

what are two alternate names for the auditory tube?

nasopharynx

the auditory tube connects the ___ with the tympanic cavity

posterior 1/3

what portion of the auditory tube is a bony canal?

anterior 2/3

what portion of the auditory tube is a surrounded by elastic cartilage?

equalize air pressure in the middle ear with atmospheric pressure

what is the function of the auditory tube?

swallowing/yawning

the cartilaginous part of the auditory tube remains closed except during...

air-filled chamber that connects tympanic cavity to mastoid air cells

what is the mastoid antrum?

tegmen tympani (m)

what forms the roof of the mastoid antrum?

loculated, air-filled chambers that assist with reception of sound and phonation

what are mastoid air cells?

vestibulocochlear organ

the inner organ houses what organ?

channels within the bone

what is the bony labyrinth?

membrane bound channels

what is the membranous labyrinth?

equilibrium and hearing

what is the function of the vestibulocochlear organ?

perilymph and membranous labyrinth

what is the bony labyrinth filled with and what does it contain?

vestibule and semicircular canals

what structures make up the bony labyrinth?

saccule and utricle

what does the vestibule contain?

vestibule

what do the semicircular canal communicate with?