When air enters the nasal cavities, it must pass through which structure?

As air enters the nasal cavities, it travels into the pharynx, which serves as a crucial passageway for both air and food. The pharynx is located posterior to the nasal and oral cavities and acts as a funnel, directing air from the nasal cavities to the larynx and subsequently into the trachea for distribution to the lungs. This anatomical arrangement is vital for ensuring that airflow is properly channeled into the respiratory system while keeping the pathways for food separate.

In contrast, the trachea and bronchi are structures further down the respiratory tract that become involved only after air has passed through the pharynx. The larynx, while also involved in the passage of air, comes into play immediately after the pharynx; however, the pharynx is the correct structure that must be traversed first when air enters from the nasal cavities. Thus, understanding the sequential pathway of airflow in the respiratory system highlights the importance of the pharynx as the immediate conduit following the nasal passages.