Embryology of Ear : Most commonly asked questions

Embryology of EAR 

Line of incision between Pinna and tragus is called Incisura Terminalis . If this union is not complete , it is called preauricular sinus . If it is asymptomatic no treatment required . 

Small pinna = Microtia 

Absent pinna = Anotia

Pinna development completed by 20th week . 

Normal shaped pinna has 2 curveture : Helix and Antihelix . 

If antihelix is absent it is called Bat Ear                                           Bat EAR 

 Note: Plastic reconstruction of pinna is done by 6 years of age .

           Because pinna attained full size by that year of age .

 Size of ossicles :  Malleus > Incus > Stapes ( MIS)  . Stapes is the smallest bone in human body . 

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Chochlea has 2 and half turn .If cochlea has one and half turn it is called Mondini's dysplasia of cochlea = common cavity cochlea . The patient is deaf since birth .Cochlear dysplasia is NOT contraindication to surgery . 

Complete absence of cochlea = Michel's aplasia . It is contraindication to surgery . Treatment of choice is = Auditory Brain Stem Implant Surgery .

Note : Ear structure already sdult size at birth are :   Middle ear , Ossicles , Cochlea  (COM) 

Ear stucture absent at birth is Mastoid tip . It develops by 2 years of age . 

Tympanic bone parts are : Mastoid , squamous , tympanic and petrous 

Bat EAR