The mouth is the beginning of the digestive system which takes in food and mixes it with saliva produced by glands located in the mouth.
Formation and Orientation
The first part of the mouth is the mouth cavity which contains the teeth and is limited by the lips, the roof, which is the hard and soft palate, and the floor of the mouth. This is the space where food is kept before it moves on to the esophagus. The orifice of the mouth is the line between the lower and upper lips and is most commonly noticed when recognizing facial expression.
During the nasomedial maxillary process of the development of the embryo, a vertical groove in the top lip, called the philtrum, is formed. The deep creases at the nose to the sides of the mouth are called nasolabial folds. The lining of the mouth is made up of mucous membrane epithelium and oral mucosa.
The mouth marks the beginning of the digestive system and plays a large part in communication and speech. This area takes in food and drink then mastication (chewing) breaks the food into more digestible pieces that allows for nutrients to be absorbed and used. It is also a part of the respiratory system allowing the exchanges of gases as they leave and enter the lungs.
Image Caption: Medical illustration of a human mouth by Duncan Kenneth Winter. Part of an unpublished manuscript on medical illustration written by Winter. Credit: Duncan Kenneth Winter / Wikipedia (CC BY 2.0)