The mouth is the first portion of the alimentary canal that receives food and begins digestion by mechanically breaking up the solid food particles into smaller pieces and mixing them with saliva.[1] The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.
In addition to its primary role as the beginning of the digestive system, in humans the mouth also plays a significant role in communication. While primary aspects of the voice are produced in the throat, the tongue, lips, and jaw are also needed to produce the range of sounds included in human language.
The gastrointestinal tract starts in the oral cavity (mouth) where your teeth grind and chew food, breaking it into small manageable pieces. This chewing process, known as mastication, is dependent upon powerful muscles (masseter and temporalis), as well as smaller muscles that permit fine control; they move the mandible (lower jawbone) against the upper jaw and enable crushing of relatively hard food. Mastication causes exocrine glands under the tongue and in the back of the mouth to secrete a watery liquid called saliva which performs two essential functions. It moistens and compacts the chewed food so your tongue can roll it into a ball (bolus) and push it to the back of your mouth for swallowing and easy passage through the pharynx and esophagus. In addition, saliva contains digestive enzymes (eg. salivary amylase) which begin the breakdown of carbohydrates. Mastication and saliva secretion work in harmony: chewing increases the surface area of foods which helps to accelerate the breakdown of starch molecules into simple sugars by the digestive enzymes. Almost no protein or fat digestion occurs in the mouth, except for the release of lingual lipase an enzyme secreted by Ebner's glands on the dorsal surface of the tongue.
