The function of the pharynx is to transfer food from the mouth to the esophagus and to warm, moisten and filter air before it moves into the trachea. The pharynx is a part of both the digestive and respiratory systems.
The pharynx, which is located behind the mouth and nose, is also known as the throat. When food is pushed to the back of the mouth by the tongue, the trachea or windpipe closes, and the food moves into the pharynx. Then, a combination of both voluntary and involuntary muscles work to swallow the food, forcing it into the esophagus, which moves it along to the stomach. A thick lining in the pharynx protects it from rough food particles and harsh chemical food components.
When not being used to transfer food, the pharynx provides a place for air to warm up and acquire the proper humidity levels before it enters the trachea and moves into the lungs. Air passes through the nose or the mouth directly into the pharynx. The mucous lining of the pharynx filters dust particles and other contaminants out of the air. The air then flows through the larynx at the top of the trachea and continues on to the lungs.