Which two sinuses are visualized in a SMV projection of the sinuses with a horizontal beam?

Which two sinuses are visualized in a SMV projection of the sinuses with a horizontal beam?

• A. Frontal and Maxillary
• B. Sphenoid and Ethmoid
• C. Ethmoid and Maxillary
• D. Sphenoid and Frontal

Answer: (B)

In the SMV view, the beam is horizontal and passes through the midline of the skull base. This path best captures the sinuses that are closest to that central axis: the sphenoid sinus and the ethmoid air cells. The sphenoid sinus lies right behind the nasal cavity along the midline, and the ethmoid air cells form a network around the nasal septum and between the orbits, so they are readily visualized when the head is positioned to allow a horizontal beam to traverse the skull base. Frontal sinuses sit higher and anterior and are often obscured by the frontal bone, while the maxillary sinuses are more lateral and better seen in other views. So the two sinuses visualized in this projection are the sphenoid sinus and the ethmoid air cells.

In the SMV view, the beam is horizontal and passes through the midline of the skull base. This path best captures the sinuses that are closest to that central axis: the sphenoid sinus and the ethmoid air cells. The sphenoid sinus lies right behind the nasal cavity along the midline, and the ethmoid air cells form a network around the nasal septum and between the orbits, so they are readily visualized when the head is positioned to allow a horizontal beam to traverse the skull base. Frontal sinuses sit higher and anterior and are often obscured by the frontal bone, while the maxillary sinuses are more lateral and better seen in other views. So the two sinuses visualized in this projection are the sphenoid sinus and the ethmoid air cells.