Download 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



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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:

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infection of the auricular
cartilage-----necrosis ---deformity.
Haematoma
Surgery
RX:

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ABX
Incision & drainage
Removal of necrotic tissue
Otitis externa
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Acute otitis externa:

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Pathophysiology:

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pseudomonas aeruginosa, staphlococcus (furuncle)
SSx:

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aggressive washing the wax or retention water
Microtruma (cotton swabs,fingernails )
Pathogens;

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Bacterial infection involving the skin of the external
canal
pain ,tragal tendreness otalgia ,pruritus, edematous
erythematous EAC, conductive hearing loss.
RX:

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suction cleaning
Ear drop
Analgesia
Antibiotic
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Eczematous otitis externa:

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SSx;

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Allergic dermatitis
pruritis ,redness oedema ,
mild pain,dry scaly skin
RX:
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recognize the allergen
Hydrocortisone cream
Antihistamin
Coal tar ointment ,silver nitrate
,canalplasty (chronic stage)
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Seborrhoeic otitis
externa :
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Cause:

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abn sebum and wax
SSx:

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Greasy, scaling and
crusting condition
Greasy yellow scales
itching
RX:

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Shampoo selenium
sulphide and ketoconazole
Ointment; salicylic acid and
sulpher 2%
 Herpetic

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Herpes simplex (acyclovir in severe cases
)
herpes zoster oticus
•
•
•
•
•
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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):

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SSX:

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Granulation tissue in EAC at the bony
cartilagenous junction
Persist otalgia, otorrhea
Crainal nerve involvement
VII, IX ,X XI ,XII,V,VI
DX ;

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Pseudomonas infection occurring in elderly
diabetic patients .
CT scan, bone scan ,culture
RX:
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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
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Acute mastoditis
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Management of recurrent
acute otitis media :
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Myringotomy with pressure
equalization tube;
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Secretory otitis media (otitis media
with effusion)

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SSX:

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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.
