General Medical Information

Sinus Anatomy And Function

Ronald G. Amedee
Andrew J. Miller

Paranasal sinus anatomy is highly complex and quite variable from person to person. Differences in structure also can exist between the two sides in the same person. Detailed knowledge of anatomy of the sinuses is extremely important in performing procedures such as functional endoscopic sinus surgery, intranasal orbital decompression, and transsphenoidal hypophysectomy. This chapter provides a comprehensive explanation of the anatomy and function of the paranasal sinuses. Embryology of the sinuses and accessory structures is detailed. Anatomy of the sinus is discussed with particular attention to important landmarks and structural relations. Physiology of the paranasal sinuses is reviewed with descriptions of the sinus epithelium, the mucous blanket, and the ostiomeatal complex. The chapter concludes with an overview of prevailing theories concerning function of the sinuses.

There are eight paranasal sinuses—four on the right and four on the left side of the nose. They are the frontal, ethmoidal (anterior and posterior), maxillary, and sphenoidal sinuses. Each sinus is lined with a mucous membrane that is continuous with the mucosa of the nasal cavity through an ostium. Under normal anatomic and physiologic conditions, the sinuses are filled with air; however, deviations from normal anatomic structure or changes in mucous membrane function predispose a person to sinus disease.