DEVELOMPMENT OF THE EAR

Dr Shittu LAJ

objectives

1. Define otic placode, otic pit, otic vesicle, endolymphatic duct and sac, spiral organ (of corti), and semicircular ducts.

2. Discuss the embryological basis of the following congenital anomalies; endolymphaticus, deafness etc.

THE EAR

- Three Anatomical Parts - - external - middle - internal

Development of the Inner Ear

Early 4th week - From Myelencephalon Otic placode otic pit otic vesicle (otocyst) Endolymphatic duct and sac utricular and

saccular portions Cochlea

Development of Middle Ear:

Tubotympanic recess (Dis.) Tympanic cavity (Prox.) Eustachian tube

Tympanic Cavity Auditory ossicles (Malleus, Incus and Stapes)

Mastoid antrum and mastoid processes

Development of External Ear:

The external acoustic Meatus - develops from the dorsal end of the first branchial groove.

-NB: Primordium of Tympanic membrane is the first branchial membrane

Congenital Anomalies of the Ear.

Hearing loss/deafness Endolymphaticus

Tympanic membrane develops from - ectoderm

- mesoderm - endoderm - auricle develops from six mesenchymal

swellings - auricular hillocks

Tympanic membrane develops from - ectoderm

- mesoderm - endoderm - auricle develops from six mesenchymal

swellings - auricular hillocks