What is the uppermost part of the respiratory tract?

The uppermost part of the respiratory tract is the nasal cavity, which primarily functions as the entryway for air into the respiratory system. It serves to filter, warm, and moisten the air before it moves deeper into the respiratory tract. The nasal cavity is anatomically situated above the pharynx, making it the starting point of the respiratory process.

While the pharynx is indeed a significant component of the upper respiratory tract, it is positioned directly behind the nasal cavity and serves as a passageway for both air and food. The larynx follows the pharynx and is involved in voice production and protecting the airway during swallowing. The trachea is even further down the tract and functions as the main airway leading to the lungs. Therefore, while the pharynx is crucial, the nasal cavity is technically the uppermost part of the respiratory tract.