Brief ear anatomy,Otitis externa ,Acute otitis media
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Transcript Brief ear anatomy,Otitis externa ,Acute otitis media
Ear anatomy& Physiology
and Embryology of the ear
+congenital anomalies
Dr. Manal Bukhari
King Saud University
Otolaryngology
Assistant professor
consultant Phonosurgeon
King Abdulaziz University
Embryology
Six visceral arches
Auricle :first and second
branchial arch
EAC: first phayrngeal groove
Ossicles :
first branchial arch (meckel’s
cartilage) malleus head and neck
incus body and short process .
Second branchial arch(reichert;s
cartilage) manubrium of malleus
,long and lenticular process of
incus ,stapes
Anatomy of the ear
External ear:
1.
Auricle :
Arise from the first and second
branchial cleft.
Cartilage +perichondrium +skin
(close adherent together) except
the lobule.
2-External auditory canal:
First pharyngeal cleft
Length:2.5 cm
Cartilaginous EAC:
lateral 1/3 fibrocartilage contains
apopilosebaceous units
Osseous EAC:
•
medial 2/3periosteum
•
Post sup squama
•
The remainder tympanic
plate
•
Squmotympanic
&tympanomastoid sutures
•
•
Two constriction :
At the medial end of the
cartilaginous portion and 5
mm from the TM
Relations of external auditory meatus
Sensory nerve supply:
Greater auricular -(C2,C3)
Auricular –vagus X
Auriculotemporal -Vc mandibular
Vascular supply:
Front: TMJ
Behind :Mastoid air cell
Above :middle cranial fossa
Front and below parotid gland
Auriculotemporal branch of superficial temporal artery ,anteriorly
Branches of postauricular division of external carotid artery postriorly.
Lymphatic drainage:
Preauricular
Postauricular
Ext jugular lymph node
Middle ear cleft
Tympanic membrane:
Outer epithelial layer
Middle fibrous layer
Inner mucosal layer
Parsa Flaccida
Parsa Tensa
Annulus Fibrosus
Notch of Rivinus
Tympanic cavity:
Bioconcave disc shaped cavity 13mm
ant post ,15 mm in height .
Eustachain tube:
Post 1/3 osseous portion open in the
ant wall of the tympanic cavity
Ant membranous cartilaginous portion
2/3 end in the nasopharynx
Length :3.7 cm ------45 degree from
horizontal
Closed at rest but opened on yawing
and swallowing (tensor paltai muscle)
Ossicles:
Transmit sound energy
from the TM to the oval
window
Malleus
head,neck ant and lat processes
and the handle (tensor tympani
muscles).
Incus
:
body ,short processes ,long
process
Stapes
:
:
head ,neck ,ant and post crura
and foot plate (stapedius)
Medial wall:
The promontory :
Oval window :
separates the middle ear from
scala tympani
Facial nerve :
occupied by the footplate of
the stapes ,closes the middle
ear from the scala vestibuli
Round window :
bony projection covering the
basal turn of the cochlea.
the horizontal portion lies
above the oval window .
The horizontal
semicircular canal :
above the second genu of the
facial nerve.
Roof (tegmen tympani)
Separate the cavity from middle
cranial fossa
Anterior wall:
Canal Huguier ,chorda tympani
Canal of tensor tympani ms
Tympanic orifice of ET
Canal of carotid artery
Posterior wall
Aditus :which lead backwards
from the epitympanum into
mastoid antrum
Pyramid (stapedius tendon)
vertical portion of facial nerve
Floor
jugular bulb
Mastoid antrum:
Situated in the post portion of
petrous temporal bone
Ant :opening of the aditus
Medial :post and horizontal
semicircular mcanals
Roof (tegmen antri)
Lat :squama and macewen’s
triangle
Nerve supply of middle ear :
Sensory :
• IX (tympanic plexus) +VII
Motor :
• V3 to tensor tympani ms
• VII to stapedial ms
Vascular supply :
Branches of both internal and
external carotid artery
Inner ear
Inner ear (labyrinth)
Osseous labyrinth
vestibule:
•
lie between the medial wall of
the middle ear and lateral end
of internal auditory canal .
• Oval window in the lateral
wall
Bony semicircular canal
• Sup ,post, horizontal
Bony cochlea;
• in front the vestibule ,snail
shell in shape ,2 1/2 turns,
central axis (mediolus )inner
wall of the canal
Contain perilymph
=extracellular fluids
Membranous labyrinth
communicating sacs and
ducts within the bony cavities
Saccule &utricle (vestibule)
Membranous semicircular
ducts
Cochlear duct (scala media)
Membranous labyrinth contain
endolymph =intracelluar fluids
↑K,↓Na
Organ of corti;
Scala vestibuli --oval window
Scala tympani -–round window
Both contain perilymph
Scala media --endolymph
Physiology of hearing
Sound energy →air →
external canal → TM →
Ossicles → cochlear fluid
wave → stimulation of
basal membrane →
shearing of hair cell with
tectorial membrane →
rapid depolarization →
impulse carried along the
auditory nerve .
Area advantage :TM 55
mm the stapes 3.2mm
=17:1
Lever effect : 1.3:1
Transformer ratio 22:1
25-30 dB gain
Central connection of cochlear
nerve
The vestibular labyrinth
Semicircular canals =hair cell ►gelatinous
cupula ► sheared (angular movements )
►vestibular nerve .
Utricle and saccule= hair cell ► otoconial
membrane ► (linear acceleration&pull of the
gravity) ► vestibular nerve
The major connection of the vestibular system
are:
spinal cord ,cerebellum, external ocular muscle
Disease of external ear and
acute otitis media
Congenital anomalies of external
ear
Protruding ear (bat
ear): otoplasty
Preauricular sinus:
surgical excision
Microtia :
Atrasia
Accessory auricles
RX:
plastic reconstruction
Bone anchored
hearing aid
Perichondritis of pinna:
it may follow:
infection of the auricular
cartilage-----necrosis ---deformity.
Haematoma
Surgery
RX:
ABX
Incision & drainage
Removal of necrotic tissue
Otitis externa
Acute otitis externa:
Pathophysiology:
pseudomonas aeruginosa, staphlococcus (furuncle)
SSx:
aggressive washing the wax or retention water
Microtruma (cotton swabs,fingernails )
Pathogens;
Bacterial infection involving the skin of the external
canal
pain ,tragal tendreness otalgia ,pruritus, edematous
erythematous EAC, conductive hearing loss.
RX:
suction cleaning
Ear drop
Analgesia
Antibiotic
Eczematous otitis externa:
SSx;
Allergic dermatitis
pruritis ,redness oedema ,
mild pain,dry scaly skin
RX:
recognize the allergen
Hydrocortisone cream
Antihistamin
Coal tar ointment ,silver nitrate
,canalplasty (chronic stage)
Seborrhoeic otitis
externa :
Cause:
abn sebum and wax
SSx:
Greasy, scaling and
crusting condition
Greasy yellow scales
itching
RX:
Shampoo selenium
sulphide and ketoconazole
Ointment; salicylic acid and
sulpher 2%
Herpetic
Herpes simplex (acyclovir in severe cases
)
herpes zoster oticus
•
•
•
•
•
lesions:
Sever pain
Vesication
Cranial nerve lesion deafness SNHL
Vertigo
Facial nerve palsies
Ramsay hunt syndrom
RX:
• oral and topical acyclovir early
Otomycosis :
SSX:
Aspergillus ,candida
moist tissue –paper dotted
gray membran, prurtic
RX
: suction cleaning
Fungicides :
• nystatin ,econazol
Otitis externa malignans (osteomyelitis
of skull base):
SSX:
Granulation tissue in EAC at the bony
cartilagenous junction
Persist otalgia, otorrhea
Crainal nerve involvement
VII, IX ,X XI ,XII,V,VI
DX ;
Pseudomonas infection occurring in elderly
diabetic patients .
CT scan, bone scan ,culture
RX:
diabetic control
Prolonged parentral anti- pseudomonus abx
Ear drop
Debridement
Hyperbaric oxygen
Acute otitis media
Inflammation of the middle ear cavity (<3
weeks)
Pathophysiology :
ET dysfunction ,spread of the infection
via submucosal lymphatic or direct
spread
Pathogens;
S,pneumonia, H, influnza.Moraxella
Risks:
Craniofacial abn
Rec URTI
Day care
Bottle feeding
smoking
immunological disorders IgA ,IgG
deficiencies
Ciliary dysfunction
Adenoid hypertrophy
GERD
NGT
SSX:
Otalgia,aural fullness, hearing loss,
tinnitus ,fever
Hyperemic TM ,non mobile bulgingTM
,air fluid level
RX;
oral ABX for 10 days
Antipyretics , analgsia oral and nasal
decongestants
Acute mastoditis
Management of recurrent
acute otitis media :
Myringotomy with pressure
equalization tube;
Secretory otitis media (otitis media
with effusion)
SSX:
nonmobile TM, airfluid levels, aural
fullness, hearing loss,
DX:
Persistence of fluid in the middle ear
space without evidence of infection.
tympanometry
RX:
ABx,
Myringotomy with pressure
equalization tube.