Clinical Anatomy of the Ear Flashcards
What is the thinnest part of the skull?
Pterion
What is the pterion a suture between?
Frontal, parietal, temporal and sphenoid bones
What bones are found in the anterior cranial fossa?
Frontal, ethmoid and sphenoid
What bones are found in the middle cranial fossa?
Sphenoid and temporal
What bones are found in the posterior cranial fossa?
Temporal and occipital
Identify each of the base of skull foraminae
What is the only part of the anterior cranial fossa where a nerve passes through?
Cribiform plate of ethmoid
Which nerves pass through the superior orbital fissure?
CNs III, IV, V1 and VI
CN V2 passes though what base of skull foramen?
Foramen rotundum
CN V3 passes though which base of skull foramen?
Foramen ovale
Which cranial nerves pass through the internal acoustic meatus?
CNs VII and VIII
CNs IX, X and XI all pass through which base of skull foramen?
Jugular foramen
Which cranial nerve passes through the hypoglossal canal?
CN XII
What are the borders of the external ear?
Auricle to tympanic membrane
What are the borders of the middle ear?
Tympanic membrane to oval window (including eustachian tube)
What are the borders of the internal ear?
Oval window to internal acoustic meatus
Most of the auricle is supplied by which nerves?
C2/C3 spinal nerves
Which nerves supply the external acoustic meatus?
CN V3 superiorly
CN X inferiorly
The skeleton of the external ear is formed from which bone?
Temporal bone
To examine the tympanic membrane in a child, the auricle should be pulled posterosuperiorly/posteroinferiorly and in an adult posterosuperiorly/posteroinferiorly
Child - posteroinferiorly
Adult - posterosuperiorly
What nerves supply sensory innervation to the tympanic membrane?
External surface - CN V3
Internal surface - CN IX
Identify the bones of the middle ear
The epitympanic recess is superior/posterior and the tympanic cavity proper is superior/posterior to the tympanic membrane
Epitympanic recess - superior
Tympanic cavity proper - posterior
What does the eustachian tube connect?
Tympanic cavity proper to nasopharynx
What is the aditus?
Opening in epitympanic recess that connects to mastoid antrum
The facial nerve travels directly from the CNS to what structure?
Internal acoustic meatus
The facial nerve gives off the chorda tympani before it moves through which structure?
Stylomastoid foramen
Once the facial nerve has given off the chorda tympani it is purely somatic motor/sensory and supplies muscles of facial expression/mastication
Motor
Facial expression
What nerve controls the inner ear?
Vestibulocochlear
Which branches of the vestibulocochlear nerve control hearing and balance?
Cochlear nerve - hearing
Vestibular nerve - balance
What are the spaces within otic capsules called?
Bony labyrinths
What do bony labyrinths contain?
Perilymph fluid
What is suspended within perilymph fluid?
Membranous labyrinth containing endolymph fluid
What structure sends APs to the brainstem via the cochlear nerve?
Cochlear duct
What structure within semicircular canals sends APs to the brainstem via the vestibular nerve?
Semicircular duct
How does sound reach the brain?
Tympanic membrane vibrates causing stapes base to vibrate creating pressure waves in perilymph that causes hair cells in the cochlea to move stimulating APs that are conveyed to brain via cochlear nerve
