Ear anatomy Flashcards
What bone are all the parts of the ear found within?
temporal bone
What are the 2 parts of the temporal bone?
squamous part and petrous part
What part of the temporal bone is the EAM found?
petrous part
What bones contribute to the pterion?
frontal; temporal; parietal and sphenoid
What is important about the pterion?
thinnest part of skull
What happens in the mandibular fossa of the temporal bone?
where the TMJ is-mandiblular connection the the skul
Where is the stylomastoid foramen found?
between the styloid and mastoid processes
What passes through the stylomastoid foramen?
facial nerve
What passes through the internal acoustic meatus?
facial and vestibulocochlear nerves and labynthine artery and vein
What is the labyrinthine artery a branch of?
the circle of Willis
What are the functions of the facial nerve?
motor to face and stapedius; taste to ant. 2/3rds of tongue; secretomotor to salivary glands and lacrimal gland and general sensory to external ear
Where is the IAM found?
just inferior to petrous ridge in post. cranial fossa
What nerve supplies the parotid gland?
glossopharyngeal nerve
What is the external ear?
aurical to tympanic membrane
What is the function of external ear?
collects and coneys sound waves to tympanic membrane
What is the function of middle ear?
amplifies and conducts sound waves to the internal ear
What is the middle ear defined as?
tympanic memrane to oval window and eustachian tube
What is the internal ear defined as?
oval window to internal acoustic meatus
What is the function of internal ear?
converts special sensory information from sound waves to fluid waves to APs
What is the external ear composed of?
temporal bone; elastic cartilage; avascular; nutrients from skin
What is the ear canal composed of?
1/3rd cartilage and 2/3rds bony
What glands produce ear wax?
ceruminous glands
What nerves supply the ear canal and tympanic membrane?
CN V3 and X
What does the vagus nerve supply?
inferior parts of EAM and tympanic membrane
What does the mandibular nerve supply?
superior parts of EAM and most of the tympanic membrane
What nerves supply the external ear?
SPINAL nerves C2 and C3
What other nerve has a supply to the external ear?
facial nerve- not really significantly
Where does lymph from the lateral surface of superior half of auricle drain to?
parotid nodes
where does lymph from cranial surface of superior half of auricle drain?
mastoid and deep cervical
Where does lymph from the rest of the auricle drain to?
superficial cervical nodes
Where does all lymph from the auricle eventually drain?
deep cervical nodes
Where are the deep cervical nodes located?
carotid sheath
What is pars flaccida?
the thin part of the tympanic membrane
Where is the pars flaccida located on the membrane?
superiorly
What is umbo?
the most inwardly depressed part of the tympanic membrane
What pars tensa?
the thick part of the tympanic membrane
Where is the pars tensa located?
posteroinferiorly
Where should the cone of light normally be directed to?
anteroinferiorly
What nerve supplies the internal surface of the tympanic membrane?
glossopharyngeal nerve
What does the glossopharngeal nerve provide sensory innervation?
middle ear cavity; eustachian tube; nasopharynx; oropharynx; tonsils
What does the eustachian tube connect?
the tympanic cavity to the lateral wall of the nasopharynx
What are the 3 bones of the middle ear?
malleus; incus and stapes
What are teh 2 muscles foudn within the middle ear?
stapedius and tensor tympani
How do the auditory ossicles articulate?
via synovial joints
What bone is adherent to the internal aspect of hte tympanic membrane?
handle of malleus
What creates the umbo in the membrane?
handle of malleus
What bone fits into the oval window?
base (footplate) of stapes
What is found superior to the tympanic membrane?
epitympanic recess
What nerve supplies tensor tympani?
V3
What nerve supplies stapedius?
facial nerve
What is found on the anterior wall of the middle ear?
superiorly- eustachian tube
inferiorly- chorda tympani exit
Where does the chorda tympani travel?
between the posterior wall between incus and malleus to the anterior wall
What is found on the medial wall?
bulge- promontery; ridges- semicircular canals; oval window; facial nerve- travelling through the facial canal from the IAM
What forms the promontery?
the cochlea
What is found on the posterior wall of the tympanic cavity?
aditus; chorda tympani enterance; stapedius
What is aditus?
doorway into the mastoid antrum from the epitympanic recess
What is the sensory innervation of the laryngopharynx?
vagus
What is the sensory innervation of the naso/oropharynx?
glossopharyngeal
Where is the facial nerves connection to the CNS?
brainstem at pontomedullary junction
What is chorda tympani?
a branch of the facial nerve
What does chorda tympani supply?
taste buds of the ant. 2/3rds of the tongue and parasym to submandibular and sublingual salviary glands
What is the function of stapedius?
reduces stapes movement to potect the internal ear from excessive noise
What does the facial canal connect?
the internal acoustic meatus to the stylomastoid foramen
What is the function of tensor tympani?
dampens the noise produced by chewing- same nerve supply as msucles of mastication
What nerve joins the chorda tympani?
the lingual nerve branch of V3
What do the muslces of facial expression originate and insert onto?
originate on bone and insert onto superifical fascia
How can frontalis be tested?
raise eyebrows
How can orbicularis oculi be tested?
close eyes really hard
How can the elevators of lips be tested?
smiling
How can orbicularis oris be tested?
maintain puffed out cheeks
What is the significance of the buccal fat pad?
its loss is a clinical sign of malnutrition- gives sunken cheeks look
What are the 2 parts of the 8th cranial nerve?
cochlear and vestibular nerves
What is the otic capsule?
extermely dense bone in temporal bone
What is contained within the otic capsule?
bony labyrinth
What type of fluid fills the bony labyrinth?
perilymph
What is suspendeed within the perilymph of the bony labyrinth?
a membranous labyrinth
What type of fluid is contained within the membranous labyrinth
endolymph
What are the 3 semicircular canals?
superior; lateral and posterior
What are the 3 parts of the cochlea?
cupula (apex of spiral) and 1st and 2nd turns
What is the cochlear duct?
a long balloon- like structure within the cochlea filled with endolymph
How are APs conducted to the brainstem from the cochlea?
cochlear nerve
How do APs from the semicircular ducts reach the brainstem?
via the vestibular nerve
What are clusters of hair cells called?
maculae
What do the utricles detect?
horizontal movement change
What do the saccules detect?
vertical movement change
What do the semicircular ducts detect?
angular movement change
How are hair cells stimulated?
by movement of endolymph
Where are hair cells found?
at specific sites in the ampulla
How is sound trasmitted through the internal ear?
sound waves make tympanic membrane vibrate; which are transmitted through ossicles; base of stapes vibrates in oval window which creates pressure waves in perilymph which changes shape in membranous ducts which moves the hair cells in the cochlea, pressure waves descen and become vibrations again which are dampened at the round window
What detects auditory stimuli?
receptor cells in the organ of Corti
Where is the organ of Corti located?
basilar membrane of cohlear duct
What suspends the cochlear duct?
spiral ligamnet
What is the cochlear canal divided into?
scala vestibuli and scala tympani
Where does CN VIII connect with the brainstem?
pontomedullary junction
