External ear Flashcards
extends from
auricle to tympanic membrane
margins of auricle
helix (top)
tragus (medial)
lobule (bottom-inf)
blood supply
posterior auricular
superficial temporal
innervation
back of ear: great auricular
Auriculotemporal: front of ear (branch CN V3) including ext auditory meatus
ext auditory meatus
outer 1/3: cartilage
inner 2/3: bone
cerumen: earwax
Tympanic membrane innervation
external (facing ext aud. meatus): auriculotemporal
internal (facing medial side): glossopharyngeal
Middle ear
PETROUS PART temporal bone
tympanic cavity proper
epitympanic recess
Walls of middle ear
Roof: tegmental wall (tegmen tympani bone (thin)) (above is middle cranial fossa)
Floor: jugular wall (bone seperates tympanic cavity from superior bulb of int jug. vein)
Lateral: Tympanic membrane (membranous), superior part epitympanic recess
Medial: promontory, labyrinthine wall
Posterior: mastoid antrum (communicates with cavity via aditus), facial nerve
Ant: carotid
Eustachian tube/ Pharyngotympanic tube
posterolateral (part closest to tympanic cavity)-bony
remainder is cartilage
Blood supply et
Ext carotid artery-ascending pharyngeal
maxillary artery-middle meningeal, artery of pterygoid canal
innervation et
Tympanic plexus (From CN 9) Pterygopalatine ganglion
Middle ear bones
Auditory ossicles, very small bones, connects tympanic membrane to oval window
Malleus (hammer): attached to tympanic membrane
Incus (anvil)
Stapes (stirrup): base sits in oval window
tympanic membrane vibrates, vibrates through these bones, relays info to stapes, then to oval window
Muscles of middle ear
Tensor tympani: CN V3 (mandibular branch)
Stapedius: facial nerve
Tensor tympani
Petrous part temporal bone and auditory tube
handle of malleus
stiffens tympanic membrane, reduces movement possible
CN V3 (motor)
Stapedius
posterior wall middle ear
stapes
pulls stapes, reduces movement at oval window
Facial nerve
