Ear and auditory apparatus Flashcards
What are the three parts of the temporal bone?
squamous
tympanic
petrous
The thin scale-like region of the temporal bone? What are the important landmarks on this part?
Squamous part has zygomatic process that contributes to the zygomatic arch and includes the mandibular fossa and articular tubercle of TMJ, inferiorly.
Which part of the temporal bone helps form the borders of external auditory meatus?
tympanic part
What is the largest part of the temporal bone? What important landmarks are on this part?
petrous part of the temporal bone has the mastoid process, styloid process and internal auditory meatus
The mastoid process is the attachment site for which muscles?
SCM
Splenius capitis
posterior belly of digastric
The internal auditory meatus connects to which cranial fossa? What passes through it
posterior cranial fossa
CN 7 and 8 pass through it (facial and vestibulocochlear nerve)
The styloid process is the attachment site for which muscles?
stylohyoid
styloglossus
stylopharyngeus
The styloid process is the attachment site for which ligaments?
stylohyoid
stylomandibular
What encloses, stabilizes and preserves the orientation the elements of the inner ear?
the petrous part of the temporal bone
The inner ear consists of 2 parts. What are they?
osseous labyrinth
membranous layrinth
What is the osseous labyrinth?
a network of bony canals in the inner ear
What is the membranous labyrinth?
a network of membranous canals enclosed within the osseous labyrinth of the inner ear
What are the elements of the auditory apparatus?
external ear
tympanic membrane
tympanic cavity/middle ear
inner ear
The portion of the external ear that functions to collect and funnel sound waves?
auricle or pinna
The osseous opening in the temporal bone that divides the external and middle ear?
External auditory meatus
The thin, transparent membrane that serves as a partition between the external auditory canal and the middle ear cavity?
tympanic membrane
What is the shape of the tympanic membrane and how is it oriented?
It is oval (11mm tall and 9 mm wide) and oriented obliquely to the vertical plane with inferior edge more medial
What causes the tympanic membrane to oscillate?
air and bone conduction
What nerves share general sensory innervation to the tympanic membrane?
V3 is the major contribution but CN 9 (glossopharyngeal) and CN 10 (vagus) also contribute
What supplies blood to the tympanic membrane?
maxillary artery
posterior auricular artery
What appears as a streak from the superior edge towards the middle of the tympanic membrane?
the manubrium of the malleus
What is the central portion of the tympanic membrane?
umbo
What does the umbo correspond to?
the tip of the manubrium
The part of the tympanic membrane that is taut?
pars tensa
The part of the tympanic membrane that is lax/slack along superior aspect?
pars flaccida
Light from otoscope reflects off the tympanic membrane back to the examiners eye. What is this reflection called and where on the tympanic membrane is it located?
cone of light is located on the anterioinferior portion of tympanic membrane
Another name for the middle ear?
tympanic cavity
In what bone structure is the middle ear enclosed?
petrous part of temporal bone
The middle ear is lined by what?
mucosa
The Eustachian tube exits the middle ear and passes to the nasopharynx at the ostium of the Eustachian tube. The first 1/3 of the tube’s length is formed by _____ and the next 2/3 of the tube’s length is formed by _____.
bone
hyaline cartilage
As the Eustachian tube exits the middle ear, does it widen or narrow as it passes to the nasopharynx?
widens
What are the two primary functions of the Eustachian tube?
- drain secretions out of middle ear
- equalize pressure of middle ear and external pressure
What is the space posterior to the tympanic cavity and superior to and continuous with the mastoid air cells? What is is lined with?
mastoid antrum lined with mucosa
The largest ear ossicle that is shaped like a hammer and attached to the tympanic membrane?
malleus
The ear ossicle that is shaped like an anvil?
incus
The ear ossicle that is shaped like a stirrup?
stapes
What part of the malleus articulates with the incus?
the head
What are the parts/projections of the malleus? What articulates with the tympanic membrane? What articulates with the incus
anterior process
lateral process (articulates with tympanic membrane)
manubrium process (articulates with tympanic membrane, tensor tympani attaches here)
head (articulates with body of incus)
What are the parts/projections of the incus? Which articulates with the stapes? What articulates with the malleus?
short process long process (articulates with head of stapes) body (articulates with head of the malleus)
What are the parts/projections of the stapes? What articulates with the incus? What articulates with the oval window of inner ear?
head (articulates with long process of incus)
neck (stapedius muscle attaches here)
crura (paired legs)
base/footplate (articulates with oval window inner ear)
What is the function of the middle ear ossicles?
to couple vibrations of the tympanic membrane to movements of the footplate of stapes which cause pressure changes in fluid of inner ear to produce sound
Articulations between ear ossicles are what kind of joints?
synovial
What are the functions of the labyrinths in the inner ear?
auditory reception vestibular reception (balance)
What are the three parts of the osseous labyrinth?
- vestibule
- cochlea
- semicircular canals
What are the two openings from the inner ear vestibule to the middle ear? What covers each of them?
oval window covered by footplate of stapes
round window covered by secondary tympanic membrane
What are the dilations at one end of each semicircular canal?
ampullae
How many turns does the cochlea make around its central axis?
2.75
The osseous labyrinth is filled with what?
perilymph
The membranous labyrinth is suspended in the osseous labyrinth and filled with what? What surrounds the ducts of the membranous labyrinth?
endolymph fills it and perilymph surrounds it
Specialized vestibular sensory receptor inside utricle and saccule of membranous labyrinth?
macula
The maculas of the utricle and saccule monitor what type of motion?
static head position and linear motion
All three semicircular canals communicate with what structure in the vestibule of the inner ear?
utricle
What are the specialized sensory receptor that line the ampulla at the ends of each semicircular canal?
crista ampullaris
What motion do the crest ampullaris monitor?
angular/rotational motion
What is the duct that extends inward from the vestibule to connect to the sac just deep to the cranial dura?
endolymphatic duct
What is the function of the ends-lymphatic duct?
to deliver endolymph just deep to the cranial dura for resorption
The trochlear duct of the membranous labyrinth communicates with what structure in the vestibule of the inner ear? Communication occurs via what structure?
communicates with the succule via the ductus reuniens
The series of auditory receptors that is continuous along the full length of the cochlear duct?
organ of corti
The spiral ganglion located along the turns of the cochlear canal contains cell bodies from which cranial nerve?
CN 8, vestibulocochlear nerve
Axonal fibers of cochlear neurons from vestibulocochlear nerve (CN8) are contained in what structure of the membranous labyrinth?
organ of corti
What is another name for the vestibular ganglion and where is it located?
Scarpa’s ganglion, located within the internal auditory meatus
What do the vestibular neurons from vestibulocochlear nerve (CN8) innervate?
Macula of utricle
Macula of saccule
crista ampullaris
Waves of perilymph hydraulic pressure are created by what?
movement of the stapes footplate that is transferred to the perilymph
Waves of perilymph hydraulic pressure ascend the cochlear canal in the _____
scala vestibuli
Waves of perilymph hydraulic pressure descend the cochlear canal in the _____
scala tympani
Waves of perilymph hydraulic pressure dissipate as vibrations in the _____
secondary tympanic membrane in the round window
Different parts of the organ of corti are maximally stimulated depending on what?
pitch of the sound
The basal end of the organ of Corti is most responsive to what kind of sound?
high pitch
The distal end of the organ of Corti is most responsive to what kind of sound?
low pitch
If the auditory apparatus is exposed to excessively loud sounds, what is sensitive to damage by that sound?
the organ of Corti
What is the origin and insertion of the tensor tympani muscle?
O: bony canal that lies superior and parallel to the Eustachian tube
I: manubrium of the malleus
What innervates tensor tympani?
medial pterygoid nerve from mandibular nerve V3
What is the action of tensor tympani?
pulls the malleus and tympanic membrane medially
What is the origin and insertion of the stapedius muscle?
O: wall of tympanic cavity
I: neck of stapes
What innervates stapedius?
nerve to stapedius which is a branch of facial nerve (CN 7)
What is the action of the stapedius?
attenuate movements of the stapes
What is the combined function of the inner ear muscles, tensor tympani and stapedius?
contract in response to exposure to loud noises to protect the organ of Croti from damage by decreasing the movements of tympanic membrane and ossicular chain
Facial nerve branches within what bony structure to give off ________ nerve which enters the tympanic cavity.
chorda tympani branches from facial nerve within petrous part of temporal bone
What are the two types of fibers that are included in chorda tympani?
- taste fibers from anterior 2/3 of tongue (travel from lingual to facial nerve via chorda tympani)
- preganglionic parasympathetic fibers traveling to submandibular ganglion
The chorda tympani traverses the tympanic cavity along the medial surface of what two structures?
manubrium and tympanic membrane
The chorda tympani exits the skull through what opening to enter the intratemporal fossa?
petrotympanic fissure
Neuronal fibers from facial nerve that travel in chorda tympani eventually hitch hike on what nerve to reach the tongue and submandibular ganglion?
lingual nerve from mandibular (V3) nerve
What are the two major components of the tympanic plexus?
- fibers from internal carotid plexus
- tympanic branch of glossopharyngeal nerve (CN 9)
What are the neuronal processes from the internal carotid plexus that contribute to the tympanic plexus?
postganglionic sympathetic neurons from superior cervical ganglion that provide sympathetic innervation to the vessels in the tympanic cavity (vasomotor)
What are the two types of neuronal processes from the tympanic branch of the glossopharyngeal nerve that contribute to the tympanic membrane?
- general sensory neurons that innervate the mucosa of Eustachian tubes, tympanic membrane/cavity and mastoid antrum and air cells
- preganglionic parasympathetic neurons from glossopharyngeal nerve (CN 9) that pass through the tympanic cavity to form the lesser petrosal nerve to reach the otic ganglion where they synapse and provide secretomotor innervation to the parotid gland