The oral cavity is the initial part of the digestive tract, where the food is received, the saliva produced, and the digestion process started.

Besides the digestion functions, the oral cavity also provides such functions as speech formation and respiration.

The oral cavity is located anteriorly in the lower part of the face and head right under the nasal cavity. It begins at the border between the facial skin and the lips.

The oral cavity has two parts or divisions, two openings, and four walls.

The parts of the oral cavity include:

• Oral vestibule - located anteriorly; it is the area bounded externally by the lips and cheeks and internally by the teeth and gingiva; the oral vestibule is connected with the outer environment via the orifice of the mouth, which is surrounded by lips;
• Oral cavity proper - located posteriorly to the oral vestibule; it is the part of the oral cavity behind the teeth, extending from the alveolar arches of maxilla and mandible anteriorly and laterally, reaching the entry into the oropharynx posteriorly; it is formed by soft and hard palate, three pairs of salivary glands and occupied by the tongue.

As mentioned above, the oral cavity contains two openings.

The first one is the anterior opening, and it is called the orifice of the mouth or the oral fissure, and it connects the oral vestibule with the outer environment.

The posterior opening leads into the initial part of the pharynx, known as the oropharynx. The junction between both parts is known as the oropharyngeal isthmus or the oropharyngeal opening.

The walls of the oral cavity are as follows:

• Roof - formed by hard palate anteriorly and soft palate posteriorly; it separates the nasal cavity from the oral cavity;
• Two lateral walls - formed by soft tissue and mastication and facial muscles of the cheeks (mainly by the buccinator muscle);
• Floor - mostly the mylohyoid and geniohyoid muscles make this part; sublingual and submandibular salivary glands are located in the floor.

The surfaces within the oral cavity are mostly lined with a mucosal membrane - the oral mucosa.