Swallowing is a complex process. Some 50 pairs of muscles and many nerves work to move food from the mouth to the stomach. This happens in three stages. First, the tongue moves the food around in the mouth for chewing. Chewing makes the food the right size to swallow and helps mix the food with saliva. Saliva softens and moistens the food to make swallowing easier. During this first stage, the tongue collects the prepared food or liquid, making it ready for swallowing.
The second stage begins when the tongue pushes the food or liquid to the back of the mouth, which triggers a swallowing reflex that passes the food through the pharynx (the canal that connects the mouth with the esophagus). During this stage, the larynx (voice box) closes tightly and breathing stops to prevent food or liquid from entering the lungs.
The third stage begins when food or liquid enters the esophagus, the canal that carries food and liquid to the stomach. This passage through the esophagus usually occurs in about 3 seconds, depending on the texture or consistency of the food.