The nasal cavity (or cavity of nose, latin: cavum nasi, cavitas nasi) is an irregular, bilateral air-filled space located above the roof of the mouth forming the internal part of the nose. The nasal cavity is an initial part of the respiratory tract and lodges the organ of olfaction.
The bony frame of the nasal cavity is formed by the nasal conchae laterally, cribriform plate of the ethmoidal bone superiorly, and palatal processes of the maxilla and horizontal portion of the palatine bone inferiorly. Anteriorly, the nasal cavity opens with the nasal aperture.
The nasal cavity is lined with mucosa, and it is a part of the upper airway passage. The nasal cavity communicates with the paranasal sinuses, including the ethmoidal air cells and the frontal, sphenoidal and maxillary sinuses. The nasal cavity opens into the nasopharynx through a pair of oval openings called the choanae.
Each half of the bilateral nasal cavity has a roof, floor, medial and lateral walls, and a vestibule.
- The roof of the nasal cavity is formed by the ethmoid and sphenoid bones. The anterior slope of the roof is formed by the cribriform plate of the ethmoid bone, while the posterior slope is formed by the anterior aspect of the body of the sphenoid.
- The floor of the nasal cavity is formed by the palatine processes of the maxillae.
- The medial wall of each half of the nasal cavity corresponds to the nasal septum. The bony nasal septum is formed by the vomer and the perpendicular plate of the ethmoid.
- The lateral wall of the nasal cavity is formed by the nasal surface of the maxilla, the perpendicular plate of the palatine bone, the labyrinth of the ethmoid bone, the lacrimal bone, and the medial plate of the pterygoid process, and the inferior nasal conchae.
- The anterior wall of the nasal cavity is formed by the nasal bone and the anterior nasal aperture.
- The posterior wall of the nasal cavity is formed by the body of the sphenoid and the paired choanae.
There are several formations in the nasal cavity that are shaped like curved shelves of bone called conchae or conchas. There are three nasal conchas on each lateral wall of the nasal cavity:
- superior nasal concha,
- middle nasal concha,
- inferior nasal concha.
The superior nasal conchae and the middle nasal conchae are a part of the labyrinth of the ethmoid bone, while the inferior nasal conchae are separate bones of the skull. The nasal conchas project into the nasal cavity creating five pathways called nasal meatuses. These include:
- superior nasal meatus,
- middle nasal meatus,
- inferior nasal meatus,
- common nasal meatus,
- nasopharyngeal meatus.