15: Ear Flashcards
function of external ear
collection of sound waves
function of middle ear
translation of sound waves into mechanical energy (vibration of membranes and bones)
function of inner ear
translation of mechanical energy to electrical (neural) energy in the cochlea; also for balance in the vestibular apparatus
external ear parts
auricle, external auditory meatus, tympanic membrane
auricle blood supply
superficial temporal a.
posterior auricular a.
auricle innervations
SENSORY: auriculotemporal V3 auricular branch of Vagus X Facial Great auricular Lesser occipital
MOTOR: facial
tympanic membrane
separates the external auditory meatus from the middle ear - covered with skin externally and mucus internally
tympanic membrane blood supply
deep auricular (from maxillary a.) for external surface of membrane
anterior tympanic (from maxillary a.) for internal surface of membrane
roof of the middle ear
tegmen tympani - a thin plate of bone separating the middle ear from the middle cranial fossa
space beneath it is the epitympanic recess
floor of the middle ear
thin layer of bone separating the middle ear from the jugular foramen (posterior) and carotid canal (anterior)
posterior wall of the middle ear
aditus antrum - entrance to mastoid air cells
pyramid - entrance of the stapedius m. to insert on stapes
foramen for entrance of chorda tympani n.
innervates the stapedius m.
facial n.
aditus antrum
middle ear, entrance to the mastoid air cells (posterior “wall”)
anterior wall of the middle ear
tensor tympani m.
entrance of the pharyngo-tympanic tube
exit of the chorda tympani n.
innervates tensor tympani m.
V3 (trigeminal)
lateral wall of the middle ear
tympanic membrane
medial wall of the middle ear
promontory oval window round window facial nerve lateral semicircular canal prominence
promontory
produced by the first basal turn of the cochlea; tympanic plexus of nerves on it
oval window
membrane of the cochlea covered by the foot plate of the stapes
round window
membrane the sound travels through after it has gone through the cochlea. next it heads through the eustachian/auditory tube
lateral semicircular canal prominence
located in epitympanic recess
contents of the middle ear
malleus incus stapes tensor tympani m. stapedius m. chroda tympani n.
tensor tympani m.
inserts on malleus
innervated by trigeminal V3
stapedius m.
inserts on stapes
innervated by facial VII
pharyngo-tympanic tube (auditory tube)
cartilage + bone
equalizes air pressure on each side of the tympanic membrane
mastoid air cells
accessed through the aditus antrum
increase the volume of the mastoid process without increasing its weight (??)
inner ear
a series of canals with an auditory and a vestibular portion
between the internal auditory meatus and the middle ear
auditory portion of inner ear
cochlea and modiolus
cochlea
auditory part of inner ear; contain hair cells for transduction of vibration into neural electrical signals for hearing
modiolus
central bony pillar of the cochlea; contains spiral canals for housing the spiral ganglion and passage of the cochlear n.
vestibule
between the cochlea and the semicircular canals; contains saccule/utricle for transduction of linear motion into neural electrical signals
3 semicircular canals
anterior, lateral, posterior: dilation called the ampulla; contain crista ampullaris for transduction of angular (rotational) motion into neural electrical signals (BALANCE)
facial nerve VII is associated with
internal auditory meatus geniculate ganglion (cell bodies of SS and GSA fibers) stylomastoid foramen (GSA - concha of pinna; SVE - muscles of facial expression) branches of facial nerve near ear - greater petrosal (SS-taste, preganglionic parasympathetic GVE to pterygopalatine ganglion), stapedius chorda tympani (SS taste; preganglionic parasympathetic (GVE) to submandibular ganglion
branches of facial nerve that are SS - special sensory
geniculate ganglion
greater petrosal n. - concha of pinna and taste
chorda tympani - taste
branches of facial nerve that are GSA - general sensory afferent
geniculate ganglion
stylomastoid of foramen - concha of pinna
branches of facial nerve that are GVE - preganglionic parasympathetic
greater petrosal nerve to pterygopalatine ganglion
chroda tympani to submandibular ganglion
vestibulocochlear nerve VIII innervates
internal auditory meatus
(SS - auditory from cochlea
SS - balance from vestibular apparatus)
tympanic plexus
from CN 7, 9, and 10
CN 9 from tympanic plexus
give rise to lesser petrosal n. which contains preganglionic parasympathetic fibers that pass through foramen ovale with V3 to synapse in the otic ganglion
postganglionic parasympathetic fibers leave otic ganglion
and join the auriculotemporal nerve (of V3) for a bit and then hop off to innervate the parotid gland
arterial supply to the ear
PA and ST
posterior auricular and superficial temporal
sensory innervation to ear
top: auricular temporal from V3
middle: CN 7 and 10 (also 9)
bottom: lesser occipital and greater auricular from cervical plexus
facial nerve VII has these branches/parts in the ear
greater petrosal
geniculate ganglion
nerve to stapedius muscle
chorda typmani
travels from stylomastoid foramen to internal acoustic meatus
