Auditory pathway Flashcards
What is the hardest part of the skull?
The petrous bone
What part of the ear sits on the petrous bone?
Cochlear
What runs through the internal acoustic meatus?
Facial nerve and vestibulocochlear nerve
What bone is attached to the tympanic membrane of the middle ear?
The ossicles
What are the 3 parts of the Ossicles?
Incus, Malleus and Stapes bone
Why is air allowed to go to the middle ear and via what pathway?
Via the auditory tube and ensures equilibrium in the skull
What is the course of energy/wave from the outside to the inner ear?
External ear = Sound waves
Middle ear = Sound waves g mechanical
Inner ear = Mechanical g electrical
What two structures is the middle ear attached to?
Connected to the nasopharynx and the mastoid air cells
Why is the middle ear phone to infection via auditory tube?
Due to the middle ear being connected to the nasopharynx
What is the possible negative consequence of the middle ear being connected to the mastoid air cells?
Infection may spread to middle cranial fossa
Why is there a thrombosis risk of the middle ear?
Due to the internal jugular vein lieing inferior
What is the cause of pulsatile tinnitus
?
Internal carotid artery lies anterior and the pulse nockes on the osicles
What is the middle ear at risk of being it is traversed by chorda tympani and facial canal?
Infection risk
What is the route of the middle ear to the tongue?
Chordna tympani nerve
What is the route of the middle ear to the partoid gland?
lesser petrosal nerve
What is the connection between the middle ear and facial muscles?
Via the facial nerve (7)
Where is the inner ear found?
The bony labyrinth which is the rigid, bony outer wall of the inner ear in the temporal.
What are the 3 cavities of the temporal bone?
Semicircular canals, vestibule and cochlea
What is contained within the inner ear?
Contains perilymph wich is a extra cellular fluid
What is extra cellular fluid?
Fluid which is high in sodiu and low in potassium
What structure does the Stapes bone sit on?
The oval window.
When the osicle bones are vibrated the stape vibrates the oval window.
What is the cochlear duct?
A membranous sac that runs through the cochlea
What is contained within the cochlear duct?
Contaiend with endolymph which is intracellular and has low levels of sodium and high levels of potassium.
The cochlear duct seperates the cochlea into what?
Into two chambers
Scala vestibule and the scala tympani
What is the position of the Scala vestibule and Scala tympani in the Cochlea?
Scala vestibule sits above the cochlear duct
The Scala vestibulea t the top of Cochlea duct become the Scala tympani which is underneath the duct.
Scala Vestibule and Scala tympani are continous at what point?
These two chambers are continuous at the apex of the cochlea – helicotrema