Audition Part 1 Flashcards
What are the three parts of the ear?
external, middle, inner ear
What is the auricle of the external ear made of?
elastic cartilage covered with skin and sebaceous glands associated with hair
What are six regions of the external ear?
helix, antihelix, tragus, antitragus, concha, lobule
What are ceruminous glands and what is their purpose?
modified apocrine glands that secrete cerumen. this protects the ear canal from physical damage and microbial invasion
What is ear wax made up of?
cerumen and desquamated meatal cells
What 5 nerves innervate the external ear (sensory innervation)?
greater auricular (majority of the auricle), lesser occipital (helix), auriculotemporal (from V3, medial auricle), Facial nerve (CN7, concha), Vagus (CNX, external auditory meatus and concha)
What nerve innervates the middle ear?
The glossopharyngeal (CN IX)
What is in the middle ear?
The tympanic cavity, ossicles, their muscles and the auditory (eustachian) tube that connects to the nasopharynx
What muscles open the auditory (Eustachian) tube?
levator/tensor palati and the salpingopharyngeus muscles
What are the three ossicles named from the tympanic membrane to the oval window?
malleus, incus, stapes
What are two muscles in the inner ear? What nerve innervates them?
Tensor tympani (dampens low frequency vibrations) innervated by V3 Stapedius innervated by VII
What is the chorda typani? What does it do?
nerve that branches from facial nerve to join V3 in the tympanic cavity. contains sensory to anterior tongue, parasympathetics to submandibular and siblingual salivary glands.
What nerve is possibly impacted by otitis media?
chorda tympani (of CN VII, facial nerve)
What is the umbo?
central depression on the tympanic membrane created by tension from the malleus
What are five visual landmarks in auriscopic view?
malleus, incus, stapes, cone of light and flaccid/tense parts
What is otitis media?
infection of the middle ear, fluid builds up in the tympanic cavity, can be drained by a tube inserted into the membrane
How can otitis media lead to meningitis or brain abscesses?
infection can spread through the tegmen tympani and through the dura into the brain from the middle ear
What is cholesteatoma?
a skin cyst from the ear canal that migrates through the tympanic membrane, grows out of control and damages the middle ear and mastoid
What is the inner ear made of?
the cochlea
What three structures can the cochlea be divided into?
the chochlear duct (scala media), the scala vestibuli and the scala tympani
What two membranes separate the cochlear duct from the other spaces?
the vestibular and basilar membranes
What kind of fluid is in the cochlear ducts and what cells secrete it?
endolymph (high K+), made by stria vascularis
What kind of fluid is in the scala vestibuli and scala tympani?
perilymph (high Na+)
Where to the scala vestibuli and scala tympani meet?
the apex (helicotrema) of the cochlea