What is the embryology of the paranasal sinuses involved in acute sinusitis?

Updated: Apr 22, 2020
  • Author: Ted L Tewfik, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

To properly diagnose and treat infectious disorders of the paranasal sinuses, the clinician should have knowledge of the developmental milestones. The development of the paranasal sinuses begins in the third week of gestation and continues until early adulthood.

During the third week of embryonic development, proliferation and medial migration of ectodermal cells form the notochord. After the heart tube and pericardium have rotated from the cranial position to lie anteriorly, the notochord, which is initially in the caudal region of the embryonic disc, rotates to lie posterior to the primitive foregut. The paraxial layer of mesenchyme, which lies adjacent to the notochord, differentiates into the somite ridges, intermediate cell mass, and lateral plate mesoderm. From these mesodermal structures the branchial arches develop, the first of which gives rise to internal nasal structures.

The paranasal sinuses develop in conjunction with the palate from changes in the lateral wall of the nasal cavity. At 40 weeks' gestation, 2 horizontal grooves develop in the mesenchyme of the lateral wall of the nasal cavity. Proliferation of maxilloturbinate mesenchyme between these grooves results in an outpouching of tissue medially into the nasal lumen. This outpouching is the precursor of the middle and inferior meatus as well as the inferior turbinate. Ethmoidoturbinate folds develop superiorly to give rise to the middle and superior turbinates. Once the turbinate structures are established, sinus development begins and continues until early adult life.


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