2. Nasal Cavity:

The nasal cavity begins at the bony nasal aperture and ends at the caudal openings (the choanae). It is divided into two symmetrical halves by the nasal septum. The nasal septum is composed of cartilage (septal cartilage) and bone (e.g. perpendicular plate of ethmoid, septal processes of frontal and nasal, and the sagittal portion of the vomer).

The dorsal and ventral nasal conchae divide each side of the nasal cavity into four meatuses (e.g. nasal passages). The dorsal nasal meatus lies between the dorsal concha and the nasal bone. The middle nasal meatus lies between the dorsal and ventral conchae, whereas the ventral nasal meatus lies between the ventral concha and the floor of the nasal cavity. The previous meatuses communicate at the common nasal meatus on the sides of the nasal septum.