Temporal Bone and Ear Flashcards
What does the petrous temporal bone house?
vestibulocochlear apparatus
What is the direction of the petrous temporal bone?
passes obliquely anteromedially
Where do CNIII and CNII enter the petrous temporal bone?
the internal acoustic meatus
What is posterior to the petrous temporal bone?
groove for sigmoid venous sinus
What passes through the stylomastiod foramen?
CNVII which emerges to supply the muscles of facial
What are the two parts of CNIII?
vestibular (balance) cochlear (hearing).
What is the vestibulocochlear apparatus made of and whhere is it?
CN VIII
cochlea
semicircular canals
utricle
saccule
petrous temporal bone
What is the path of the vestibular part of CNIII?
leaves the semicircular canals, utricle & saccule of the labyrinth & lies in the internal acoustic meatus with CN VII & the cochlear part of CN VIII
What is the path of the cochlear part of CNVIII?
derived from the organ of Corti in the cochlea & lies in the internal acoustic meatus with CN VII & the vestibular part of CN VIII
What are symptoms of damage of the vestibular and cochlear parts?
Balance: Ataxia, vertigo, nausea, nystagmus
Hearing: Neural or conductive loss
What is the general structure of the ear?
external
middle
internal
What are the parts of the external ear and what is their role?
Auricle & external acoustic meatus composed of cartilage & bone leading sound waves to the tympanic membrane
What are the parts of the middle ear and what is their role?
Ossicles mechanically transmitting sound; connected to pharynx by the auditory tube (eustachian, pharynotympanic)
contains the tympanic membrane
What are the parts of the internal ear and what are their roles?
Semi- circular canals (motion) & cochlea (hearing) converting mechanical signals to electrical carried by CN VIII
What is the auricle made of, what are it’s parts and what is it’s role?
elastic cartilage
helix, lobule of auricle, tragus
* Support
* ‘Catching’ & funnelling sound into the external acoustic meatus