Which sinuses open into the middle meatus?

Which sinuses open into the middle meatus?

• A. Frontal, maxillary, anterior and middle ethmoidal sinuses
• B. Frontal, maxillary, and sphenoidal sinuses
• C. Frontal and sphenoid sinuses
• D. All paranasal sinuses

Answer: (A)

The middle meatus is the main drainage pathway for several paranasal sinuses. Its semilunar hiatus collects openings from the frontal sinus (via the frontonasal duct into the frontal recess that communicates with the middle meatus), the maxillary sinus (through its ostium into the middle meatus), and the anterior and middle ethmoid air cells (via ostia on the ethmoidal labyrinth into the middle meatus). The sphenoid sinus drains into the sphenoethmoidal recess above the superior concha, and the posterior ethmoid cells drain into the superior meatus. Therefore, the sinuses that open into the middle meatus are the frontal, maxillary, and anterior and middle ethmoidal sinuses.

The middle meatus is the main drainage pathway for several paranasal sinuses. Its semilunar hiatus collects openings from the frontal sinus (via the frontonasal duct into the frontal recess that communicates with the middle meatus), the maxillary sinus (through its ostium into the middle meatus), and the anterior and middle ethmoid air cells (via ostia on the ethmoidal labyrinth into the middle meatus). The sphenoid sinus drains into the sphenoethmoidal recess above the superior concha, and the posterior ethmoid cells drain into the superior meatus. Therefore, the sinuses that open into the middle meatus are the frontal, maxillary, and anterior and middle ethmoidal sinuses.