Embryology Of External Ear Flashcards
Ectodermal cleft gives rise to
EAC -- CARTILAGINOUS at birth
Bony part ( later )Mesoderm gives rise to
Mesodermal arch / brachial arch
1st and 2nd arch gives rise to
1st incus malleus
2nd supra structure of stapes
Supra structure of stapes include
Head , posterior crus and anterior crus
1st Endoderm pouch gives rise to
Tubotympanic recess
Tubo tympabium recess gives rise to
Proximal part -+ ET
Distal part – Middle ear mastoid Antrum
Patients presents with -
Defect in formation of pinna
Hearing loss
Diagnosis is ?
MEATAL ATRESIA
Anotia , microtia
Treatment of MEATAL Artesia
And how?
BAHA RECONSTRUCTION OF PINNA - - done with costal ribs - after 6 year Done in 2-3 steps
Tympanic memberan forms from
Fusion of 1st arch and 1st cleft ( all 3 germ layer )
On examination we find
-Fistula and fenestrum ant. to oval windows
- Fixation of foot plates of stapes
Diagnosis
Otosclerosis
Parts of pinna
Helix
Anti helix
Tragus
Anti tragus
Concha
Cymba concha - cartilaginous landmark of antrum
Macewen’s triangle – Bony landmark of antrum
Boundries of mastoid Antrum
Superiorly - Dural Pani
Posteriorly- Sinus plate
Inferior – Stylomastoid foramen with facial nerve
Anteriorly – posterio superior external auditory canal
Citell’s angle
Sinodural angle
Angle between sinus plate and Dural plate
Mastoid drill done in area
Mac Ewen’s triangle
Appears middle ear is done by which incision and name of incision
Endaural approach - incision on incisura terminals
LEMPERT INCISION
