Ear Flashcards
Auricle
elastic cartilage + skin
concha, helix and tragus
Muscle innervation: facial nerve
Blood supply: anterior auricular, posterior auricular
External acoustic meatus
S shaped
between auricle and tympanic membrane
lateral 1/3 cartilaginous, glands produce earwax
medial 2/3 bony
Tympanic membrane
oval, semitansparent
oscillate in respons to sound waves
pars flaccida, pars tensa
malleolar stria, umbo, malleolar prominence
4 quadrants: anterosuperior, anteroinferior, posteroinferior, posterosuperior
Innervation: auricotemporal, glossopharyngeal
Medial wall of tympanic cavity
promontory oval window round window prominence of facial canal prominence of lateral semicircular canal inlet of mastoid antrum tympanic sinus sulcus promontory opening of auditory tube tensor tympani m.
Posterior wall of tympanic cavity
antrum mastoideum fossa incudis eminentia pyramidalis canaliculus chordae tympani facial canal
Inferior wall of tympanic cavity
jugular fossa
styloid process
foramen of tympanic canaliculus
Superior wall of tympanic cavity
tegment tympani
temporal bone
groove for minor and major petrosal nerve
Anterior wall of tympanic cavity
carotid canal
opening of auditory tube
tensor tympani m.
canaliculi caroticotympanici
Lateral wall of tympanic cavity
tympanic membrane epitympanic recess manubrium mallei chorda tympani anulus fibrocartilagineus
Content of tympanic cavity
auditory ossicles
nerves: 7th, 9th and 10th cranial nerves, sympathetic fibers
Vessels
Muscles: tensor tympani m., stapedius m.
Pharyngotympanic tube
posterior half bony, anterior half cartilaginous and membranous
medial lip of cartilage- torus tubarius
Muscles: salpingopharyngeal, levator veli palatini, tensor veli palatini
Function: equalize air pressure
Endolymphatic spaces
utriculus
sacculus
ductus semicirculares
ductus cochlearis
Perilymphatic spaces
membranous and bony labyrinth scala vestibuli and scala tympani vestibulum canales semicirculares cochlea
Corticolymphatic spaces
organ of Corti
Semicircular canals
Anterior semicircular canal: -perpendicular to long axis of pyramid Lateral semicircular canal: -smallest canal -closer to horizontal plane Posterior semicircular canal: -parallel with the long axis of pyramid
Vestibule
Lateral wall: oval window
Medial wall: sperical recess, elliptical recess, cochlear recess, vestibular aqueduct
Posterior wall: five openings to semicircular canals
Anterior wall: elliptical opening to scalavestibuli of cochlea
Structures passing through fundus of internal acoustic meatus
- Facial area: facial nerve and n.intermedius
- Cochlear area: cochlear nerve, labyrinthine artery and vein
- Sup. vestibular area: utriculoampullar nerve
- Inf. vestibular area: saccular nerve
- Foramen singulare: posterior ampullar nerve
Hearing
vibration of tympanic membrane - vibration of stapes - pressure waves of perilymph - displacement of basilar membrane - shear between hair cells and tectorial membrane - bending of stereo cilia -> electrical signal
Blood supply of bony labyrinth
Middle meningeal artery
Ascending pharyngeal artery
Internal carotid artery
Blood supply of membranous labyrinth
labyrinthine artery -> common cochlear / ant. vestibular -> spiral / vestibulocochlear
Lateral bending of stereo cilia
opening of cation channels - K+ (Ca2+) influx - depolarization - opening of voltage sensitive Ca2+ channels - release of glutamate - triggering action potential in afferent fiber
Medial bending of stereo cilia
decrease in cation channel conductance - hyper polarization
