Outer–Middle–Inner Ear Embryology

Merging the six auricular hillocks is a complicated process that occurs during external ear development. Abnormal growth and development can occur in numerous areas due to the inherent intricacy of this process. During the third week of gestation, the otic disc is formed when the ectoderm thickens. An otic pit develops from the maturing otic disc. At about 32 weeks of gestation, the developing auricular complex reaches its final location, level with the eyes, after having moved dorsocranially with the mandible’s growth from its ventrocaudal origins near the neck’s base. Chromosomal aberrations are linked to the ears that are positioned more posteriorly on the skull. The auricle’s structures are formed by the merging of the six hillocks that originate from the first and second branchial arches. The tragus, helical crus, and helix most likely originate from the mandibular arch, with the initial arch spanning the first three hillocks. The second arch, also called the hyoid arch, is where the lobule, antitragus, and antihelix develop. This arch is formed by the fourth through sixth hillocks. Ear anomalies are most common before week 7 of gestation, and most growth is finished by week 20. The convergence of these hills with the ear’s intrinsic and extrinsic musculature, which creates numerous folds and curves, determines the final ear contour.