The mouth is an oval shaped cavity in the anterior side of the digestive tube. It's limited on the front by the lips, and contains the tongue and teeth. It's formed by the oral vestibule and the oral cavity.
The oral vestibule is in front of the teeth, bounded anteriorly by the lips and the cheeks and posteriorly by the gums and the teeth. It receives the parotid glands secretions, and when the maxillae are closed, communicates with the oral cavity through an opening located behind the molars and though the narrow fissures between the opposite teeth.
The oral cavity is bounded anteriorly and laterally by the alveolar arch and the teeth, and communicates posteriorly with the pharynx through the isthmus of the fauces and covered by the hard and soft palates. The majority of the floor of the cavity is formed by the tongue, the rest by the lateral mucous membrane and the back part of the tongue. The oral cavity receives the submandibular and sublingual glands secretions.