Diseases of external ear |Congenital disorder | #1 скачать в хорошем качестве

Diseases of external ear |Congenital disorder | #1

A. CONGENITAL DISORDERS The developmental abnormalities of the pinna may be just minor variations from the normal or major abnormalities. 1. Anotia. It is complete absence of pinna and lobule, and usually forms part of the first arch syndrome 2. Microtia It is a major developmental anomaly. Degree of microtia may vary. It is frequently associated with anomalies of external auditory canal, middle and internal ear. The condition may be unilateral or bilateral. Hearing loss is frequent. Peanut ear is a form of microtia. 3. Macrotia. It is excessively large pinna. 4. Atresia of external canal. Congenital atresia of the meatus may occur alone or in association with microtia. When it occurs alone, it is due to failure of canalization of the ectodermal core that fills the dorsal part of the first branchial cleft. The outer meatus, in these cases, is obliterated with fibrous tissue or bone while the deep meatus and the tympanic membrane are normal. Atresia with microtia is more common. It may be associated with abnormalities of the middle ear, internal ear and other structures. #entlectures #pgnotes #medicos