Semilunar hiatus and paranasal sinuses
- The frontal sinus is open at the top end and open to the middle nasal meatus。
- The maxillar sinus is open at the lateral wall and open to the middle nasal meatus.
- Anterior part of the ethmoidal sinus(ethmoidal cells) opens to the middle nasal meatus through the semilunar hiatus
- Middle part open to the middle nasal meatus through surface of the ethmoidal bulla. Posterior part open into the superior nasal meatus.