What is the tissue that divides the nasal cavity into two parts?

The tissue that divides the nasal cavity into two parts is known as the septum. This structure, primarily composed of cartilage and bone, runs vertically down the center of the nasal cavity, effectively separating it into the left and right nasal passages. The septum plays a crucial role in the support and structure of the nose and contributes to proper airflow through the nasal cavities.

In contrast, the ala refers to the flaring outer part of each nostril, which does not divide the nasal cavity. The philtrum is the vertical groove located in the middle of the upper lip, linking the nose to the lip, and is not involved in dividing the nasal cavity. The zygomatic arch is a bony prominence formed by the cheekbone, which relates to the structure of the face rather than to the nasal cavity specifically. Thus, the septum is the correct answer as it serves the function of separating the nasal passages.