Flashcards in Anatomy of the Ear Deck (56)
Which nerves supply sensory innervation to the outer ear?
Spinal Nerves C2 and C3
CN VII - Facial
CN V3 - Auriculotemporal a branch of the trigeminal nerve
What nerves supply the sensory innervation to the auditory canal?
CN X Vagus nerve
CN V3 Auriculotemporal a branch of the trigeminal nerve
What is the middle ear?
The tympanic cavity
What three bones are located in the tympanic cavity?
What joints are found between the three bones in the tympanic cavity?
Synovial - reduce friction and allow smooth movement.
What is special about the bones in the tympanic cavity?
You are born with fully developed bones, they don't undergo osteoclast or blast activity.
What two muscles are found in the tympanic cavity?
What is the function of the tensor tympani?
Reduces the noise from chewing by dampening the vibration caused by the malleus.
What nerve innervates the tensor tympani and the stapedius muscle and why is this key to its function?
CN V3 Mandibular branch of the trigeminal nerve
This is the nerve that controls chewing, firing off this causes both mastication and the dampening of the malleus so you don't hear yourself chew.
What is the function of the stapedius muscle?
Dampens the stapes, thus reducing the vibrations passed into the oval window.
What is the acoustic reflex?
Shouting involves CNV3 being activated to open the jaw, this also excites both the stapedius and tensor tympani so the sound is reduced for us.
How is the stapes connected to the otic capsule?
The stapes plate fits within the oval capsule.
How does the tympanic cavity amplify sound?
The tympanic membrane is much larger that the plate of the stapes, this acts as a piston, as same amount of energy is exerted from a smaller surface area.
What maintains the pressure within the middle ear?
Where does the Eustachian tube exit?
Exits in the nasopharynx
Why is it important to regulate air pressure in the middle ear?
As it will affect the oscillations of the ossicles and the tympanic membrane.
Reduced potential for barotrauma
What muscles are involved in the opening of the Eustachian tube?
Why can tonsilitis or pharyngitis mimic ear ache?
Common sensory nerve supply - CN IX
What nerve supplies sensory innervation to the tympanic cavity?
CN IX Glossopharyngeal nerve
What forms the promontory within the middle ear?
What lays over the promontory?
What organ process sound and converts it into action potentials?
The organ of corti
Where is the otic capsule located?
Within the temporal bone
What is the bony labyrinth?
Cavity of the otic capsule filled with perilymph
What is the membranous labyrinth?
Suspended within the bony labyrinth filled with endolymph
Which part of the inner ear is associated with sound?
Within the cochlear duct how is it divided?
Central organ of corti surrounded by the Scala tympani and Scala vestibuli
Where in the organ of corti are the cilia located?
Located on the basilar membrane
How are the cilia within the organ of corti moved to trigger an action potential?
Waves are created by the vibrations of the stapes foot in the perilymph. These waves push on the membrane of the organ of corti which moves the cilia.