Ear Flashcards
internal auditory meatus is for
7, 8 cranial nerves and labyrinthine vessels
tympanic canaliculus
is on petrous temporal bone between the carotid canal and jugular fossa
petrotympanic fissure gives passage to
anterior tympanic artery, anterior ligament of malleus and chorda tympani nerve
stylomastoid foramen gives passage to
facial nerve and posterior tympanic artery
hiatus for greater petrosal nerve
gives passage to greater petrosal nerve ad middle meningeal artery
whats the canal for tensor tympani muscle
TEGMEN TYMPANI (also makes roof of middle ear and mastoid antrum)
end organ for hearing
organ of corti situated in the cochlear duct
what is crista
end organ is semicircular canal
it is a receptor for kinetic balance
static balance receptors are
macula end organs in utricle and saccule
different parts of auricle
helix, antihelix, tragus, concha and scaphoid fossa
nerve supply of auricle
lateral: upper 2/3rd auricotemporal nerve
lower 1/3rd greater auricular nerve
medial: upper: lesser occipital
lower: greater auricular nerve
blood supply of auricle
superficial temporal and posterior auricular
lymphatic drainage of auricle
preauricular
and postauricular
blood supply of externa acoustic meatus
the outer part is supplied by posterior auricular superficial temporal and inner part is supplied by deep auricular branch of maxillary artery
nerve supply of external acoustic meatus
anterior half by auricotemporal
posterior half by auricular branch of vagus nerve
lymphatics of external acoustic meatus
preauricular postauricular and deep cervical lymph nodes
three layers of the tympanic membrane
outer circular layer
middle fibrous layer which is radiating fibers and the circular fibers which are more at periphery and in the pars flaccida the fibrous layer is replaced by lose areolar layer
inner mucousa layer which have ciliated columnar epithelium
blood supply of tympanic membrane
outer surface: deep auricular branch of maxillary artery
inner surface: anterior tympanic branch of maxillary and posterior tympanic branch of stylomastoid branch of posterior auricular artery.
venous dranage of tympanic membrane
1- outer surface into external jugular
2. inner surface into transverse sinus into venous plexus around the auditory tube
lymphatic drainage of tympanic membrane
preauricular and retropharyngeal
nerve supply
outer surface: auricotemporal (anteroinferior)
auricular branch of vagus nerve and communicating branch from facial nerve (posterosuperior)
inner surface: tympanic branch of glossopharyngeal from tympanic plexus
ear cough
irritation of the auricular branch of vagus nerve in external ear can causes ear cough vomitting ot even death due to sudden cardiac inhibition
herpes zoster in ear
involved with geniculate ganglion and bewteen the auricular branch of vagus nerve and facial nerve within the petrous temporal bone
cauliflower ear
bleeding occurs between the perichondrium and auricular cartilage and if fibrosis occurs the hematoma stops the blood supply causing cauliflower ear
parts of middle ear
tympanic cavity opposite to tympanic membrane
epitympanic recess above the tympanic membrane
middle ear communications
anterioly with nasopharynx trough the auditory tube
posterior to the mastoid antrum and mastoid cells through the aditus
BOUNDARIES
roof or tegmental wall
middle ear cavity is seperated from the middle cranial fossa through the tegmen tympani which also bears the tensor tympani
BOUNDARIES
floor ot jugular wall
the cavity is seperated from the superior bulb of internal jugular vein by a thin bony plate
tympani canaliculis
transmits tympanic branch of glossopharayngeal to the medial wall of middle ear
BOUNDARIES
anterior or carotid wall
superior part has opening for tensor tympani
middle part for auditory tube
inferior part makes theposterior wall of internal carotid
this late seperates the middle car cavity from the internal carotid artery
carotid wall of middle ear is perforated by
inferior and superior caroticotymanic nerves and tympanic branch of internal carotid artery
process cochleariformis
the septum between the opening of tensor tympani and auditory tube is continued in the medial wall as a lamina called as process cochleariformis
which also acts as a pulley for tensor tympani to move upwards to the handle of malleus
BOUNDARIES
posterior or mastoid wall
opening from up to downwards
superiorly aditus that connects the recess epitympanic to mastoid antrum
below aditus fossa incudis which is a depression that lodges short process of incus
between the junction of medial and posterior wall u have a conical projection called pyramids which has the passage for the tendon of stapedius
lateral to pyramid you have posterior canaliculis for the chorda tympani that is the entry for nerves in the middle ear cavity
lateral or membranous wall
seperates the middle ear cavity from the external acoustic meaturs
formed by tympanic membrane and petrous temporal bone in the region of epitympanic recess
near the tympanic notch you have two apertures which are
petrotympanic fissure which lodes the anterior process of malleus and the tympanic branch of maxillary artery
and anterior canaliculis of chorda tempani nerve which is the exit for the nerves from middle ear cavity into the base of the skull
tympanic branch of maxillary artery comes from
the petrotympanic fissure
medial wall or labryrinthine wall
- promontory- round bulging produced by the first turn of cochlea grooved by the tymapnic plexus
- fenestra vestibuli- posteriorsuperior to promontory opening to the vestibuli of internal car and is closed by the foot plate of stapes
- fenestra cochlea- posterioroinferior to promontory opens into the scala tympani of cochlea and is closed by the secondary tympanic membrane
- promince of facial canal- below the fenestra vestibuli goes to the lower margin of aditus and then posterior to the stylomastoid foramina
- prominent of lateral semicircular canal above the facial canal
- sinus tympani behind the promontory
contents of middle ear
3 bones: incus malleus and stapes ligaments of ear osscicles muscles- tensor tympani and stapedius nerves- chordo tympani and tympanic plexus air vessels
longest and most laterally placed ossicle
meatus
parts of malleus parts
- head- in the epitympanic recess
post articulates with incus
and attachement to lateral and superior ligaments - neck lies againts the pars flaccida and medially associated with chorda tympani
- anteriorly is connected to petrotympanic fissure through anterior ligament
- laterally makes the malleolar folds
- head moves backwards and downwards and is attached to upper half of tympanic membrane
incus or anvilparts
body- articulates with the head of malleus
long process- end of long process has a lentiform nodule that articulates with the head of stapes
stapes parts
small head articulates with the lentiform nodule of incus
narrow neck provides attachment posterioly to stapedius
two limbs- anterior short and less curved
posterior attached to footplate
footplate- fits into the fenestra vestibuli
joint of the ossicles
incudomalleolar- saddle joint
incudostapedius- ball and socket joint
tensor tympani is supplied by and embryonic origin
mandibular nerve (fibers pass through the nerve to pterygoid and then to otic ganglion mesoderm of first brachial arch
stapedius nerve supply and embryonic origin
facial nerve
and mesoderm 2nd brachial arch
arterial supply of middle ear
anterior tympanic branch of maxillary artery (pterotympanic fissure)
posterior tympanic branch of stylomastoid branch of posterior auricular artery (stylomastoid foramen)
petrsol and superior tympanic branch of middle meningeal artery
ascending phrangeal artery
tympanic branches of internal carotid artery
venous drainage of middle car
superior petrosal sinus and pterygoid plexus of veins
lymph drainage of middle ear
pre auricular and retropharangeal
nerves
tympanic plexus
which is made by
tympanic branch of glossopharyngeal nerve
gives off lesser petrosal nerve
supplies the middle ear, auditiry tube and mastoid antrum
inferior and superior caroticotympanic nerves from the plexus around internal carotid (vasomotor to the moucous membrane)
what is mastoid antrum
circular air filled cavity posteriorly to petrous temporal bone
boundaries of masoid antrum
superiorly- tegmen tympani
inferiorly- mastoid process with mastoid cells
ant- communicates with the epitympanic recess through aditus
posteriorly- thin bony plate seperates it from sigmoid sinus
medially- petrous temporal bone
laterally- squamous temporal bone
arterial and venous drainage of mastoid antrum
arterial: posterior tympanic branche from the stylomastoid branch of posterior auricular artery
venois: mastoid emissary vein and posterior auricular vein and sigmoid sinus
lymphatics of mastoid antrum
upper deep cervical and postauricular
fracture of middle cranial fossa causes what
the fracture of the roof of middle ear and rupture of tympanic membrane causes bleeding and leakage of csf
otitis media and its spread
when infection from throat spreads into the ear through the audiotory tube
- erodes roof and causes meningitis and brain abscess
- erodes floor and can cause sigmoid or internal jugular thrombosis
- spreads backwards can cause mastoid abscess
eustachian catarrh
inflammation of auditory tube is secondary to common cold which may cause pain in the ear while swallowing- decongestant
cause of deafness
osteosclerosis between foot plate of stapes and fenestra vestibulli
hyper acusis
paralysis of stapedius muscles causing distorted sounds and get too high in volume
internal ear
labyrinth is formed by bony labyrinth and membranous labyrinth which as the endolymph and both of them separated by perilymph
3 parts of bony labyrinth
ant cochlea
middle vestibule
post semicircular canal
receptors for sound: organ of corti
static balance
receptors for sound: maculae
static balance
receptors for sound: cristae
kinetic balance
blood supply of labyrinth
labyrinth branches of basiliar artery which is accompained by vestibulochochlear nerve
and also by the stylomastoid branch of post auricular artery
labyrinth vein drains into
superior petrosal sinus and transverse sinus
also from other places into inf and superior petrosal sinus and internal jugular vein
