Which structure is located on the midline of the face and serves as a central partition of the nasal cavity?

• A. Ethmoid bone
• B. Nasal septum
• C. Sphenoid bone
• D. Hard palate

Answer: (B)

The central partition that runs along the midline and separates the nasal passages is the nasal septum. It forms the wall between the left and right nasal cavities from the nostrils to the back of the nasal cavity, and its bony core comes from the perpendicular plate of the ethmoid and the vomer, with cartilage (nasal septal cartilage) making up the front part. The ethmoid bone contributes to the septum but isn’t the entire partition by itself; the sphenoid bone sits behind the nasal cavity, and the hard palate forms the floor, not the dividing wall. So the nasal septum is the structure that fits this description.