Extraoral anatomy in CBCT – a literature review. Part 1: Nasoethmoidal region

Cone beam computed tomography has become a widely used imaging technique for dental indications. Depending on the selected size of the field of view, anatomical structures outside the dentomaxillary complex become visible. As a consequence, the clinician must be able to interpret also those anatomical regions. In this article, the anatomy of the nasoethmoidal region is presented based on a literature review. The nose is characterized by the nasal septum and the superior, middle, and inferior conchae. The turbinates may be pneumatized (concha bullosa), mainly the middle concha. The ethmoid bone has a complex morphology (ethmoid labyrinths) and contributes with its perpendicular plate to the nasal septum. Other structures of the septum include the vomer and the septal cartilage. The nasal meatuses stabilize the airflow and direct the inhaled air to the nasopharynx via the choanae. The middle nasal meatus, which is also a part of the so called ostiomeatal complex, serves as the major drainage area (semilunar hiatus) of the paranasal sinuses, i.e., maxillary sinus, anterior ethmoid cells, and frontal sinus. Posterior ethmoid cells empty into the superior meatus and the sphenoid sinus drains into the sphenoethmoidal recess, located above the superior concha. The nasolacrimal duct that is running along the middle portion of the lateral nasal wall opens into the inferior nasal meatus.