The teeth are located inside the mouth. Humans have two sets of teeth, the first during childhood and the second set ideally throughout adult life. The lower row of teeth are inset into lower jaw bone and the upper row of teeth are inset into the upper jaw bones. The tongue is located at the floor of the mouth between the two lateral portions of the lower-jaw. The base of the tongue is connected to the midline of the floor of the mouth by a fold of membrane called the lingual frenulum and is controlled by several muscles including the hyoglossus. The salivary glands are located in the lower part of the face and secret into the buccal cavity. There are 3 main salivary glands: (1) The parotid gland is the largest salivary gland and is located on the side of the face immediately below and anterior to the external ear. (2) The submaxillary gland is located below the jaw towards the front of the neck/lower-jaw. (3) The sublingual gland is the smallest salivary gland and is located below the mucous membrane of the floor of the mouth. It is narrow and has a flatten shape, resembling an almond. The epiglottis is the flap of cartilage located at the back of the throat behind the tongue, and in front of the larynx. The trachea is not part of the digestive system but is included on the above diagram to clarify the action of the epiglottis, which acts as a switch directing food or air from the buccal cavity into either the oesophagus leading to the stomach or the trachea leading to the lungs. The oesophagus is a muscular canal that extends from the throat at the back of the mouth to the stomach. The diaphragm is a thin musculo-fibrous septum that is not part of the digestive system but is included above because it separates the thorax from the abdomen. The stomach is located between the lower end of the oesophagus and the start of the small intestines at which the pylonic sphincter of the stomach releases contents of the stomach into the first and upper-most part...