The oral cavity is divided into the oral cavity proper and the vestibule
Vestibule – This space is between the cheeks and lips externally and the teeth and gums internally. Two muscular fleshy folds -the lips, surround the oral fissure. Skin covers the lips externally, and the interior is lined with a mucous membrane.
Median folds – mucous membrane called the labial frenulae connect the lips to the gums. The lips contain the orbicularis oris, which puckers the lips and is sometimes referred to as the kissing muscle. The little groove that runs from the upper lip toward the nose is called the philtrum
Oral cavity proper – includes everything behind the teeth. The roof of the mouth is formed by the hard palate, and the floor is formed by the anterior two-thirds of the tongue and the mucous membrane that covers the sides of the tongue and attaches it to the mandible.
Cavitas Oris – the entire structure is called the mouth, the structures within the mouth allow us to taste and masticate food, to swallow food and drink, and to manipulate the air that comes up from the voice box so that we can form words. Mouth resonance is used for a conversational vocal, color in singing and, in combination with nasal resonance, it creates forward placement or mask resonance. larynx is the voice box and is also involved in sound production, breathing, and protection of the trachea from food which is aspirated. It has the vocal cords and manipulates volume and pitch,
The pharynx is the most important resonator by virtue of its position, size, and degree of adjustability. It is the first cavity of any size through which the product of the laryngeal vibrator passes. The oral cavity is the second most effective resonator