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Anatomy  

The oral cavity extends from the vermilion border of the lip to the junction of the hard and soft palate in the roof of the mouth and to the circumvallate papillae on the tongue. The oral cavity consists of the lips, commissures, tongue, floor of mouth, gingivae, buccal mucosa, retromolar trigone and hard palate.

Lip (vermilion border of the lip) is the lipstick area, extending anteriorly from the mucocutaneous junction to the area where both lips touch each other (figure 1). Buccal mucosa is the inner lining of the cheeks (figure 2). The opening of the parotid salivary gland duct, the Stensen’s duct, may be observed as a small papillary or punctate soft tissue mass on the buccal mucosa adjacent to the maxillary second molar tooth (figure 3). Labial mucosa is part of the buccal mucosa lining the inner surface of the lips (figures 4). Retromolar trigone is the small triangular area lying behind the last lower molar teeth (figures 5). The gingiva is the tissue that covers the neck of the teeth and the alveolar bone (figure 6). Alveolus is the bony ridge of the gum line containing teeth (figure 7). The oral part of tongue (anterior two thirds) is mobile (figure 8). The dorsal surface of the tongue contains several types of papillae, the most numerous being fine-pointed, cone-shaped filiform papillae, which do not contain taste buds, followed by evenly scattered mushroom-shaped fungiform papillae, which form pink nodules and do contain taste buds (figures 9). Posteriorly, there are about 8–10 bigger papillae, the circumvallate papillae, which contain many taste buds (figure 10). At the posterolateral area of the tongue, where it meets the palatoglossal fold, there are leaf-shaped foliate papillae, which contain minor salivary glands on the surface and lymphoid follicles in the core (figure 11). The under surface of the tongue is called ventrum of the tongue, which is attached to the floor of mouth by a median lingual frenum, where the submandibular salivary gland duct, also known as the Wharton duct, opens on either side (figure 12). There are several minor salivary glands in the tongue located predominantly towards the midline and deep within the lingual musculature. The floor of mouth is a horseshoe-shaped area between the ventrum of the tongue medially and the gingivae of the lower teeth anteriorly and laterally, extending to the palatoglossal fold posteriorly (figure 13). The hard palate forms the roof of the oral cavity and continues anteriorly, with the maxillary alveolar arches, and posteriorly, with the soft palate (figure 14). Most of the palatal mucous membrane is firmly bound to the underlying bone and contains numerous minor mucous salivary glands posteriorly.

The mucous membrane found on the gingivae, hard palate and dorsal surface of the tongue is known as “masticatory mucosa”. It is bound tightly to underlying tissue and covered by keratotic, relatively thick stratified squamous epithelium to withstand the trauma of chewing. The mucosa on the inner aspect of the lip, the inner aspect of the cheek, the ventral surface of tongue and floor of the mouth are elastic and covered by relatively thin, stratified squamous epithelium supported by loose fibrovascular connective tissue known as “lining mucosa”. “Specialised mucosa” refers to the taste buds.

Image	Caption
	Figure 1: Lip (vermilion border of the lip) is the lipstick area, extending from mucocutaneous junction to the area where both lips touch each other.
	Figure 2: Buccal mucosa is the inner lining of the cheeks.
	Figure 3: Opening of the Stensen duct.
	Figures 4: The labial mucosa is part of the buccal mucosa lining the inner surface of the lips.
	Figures 5: The retromolar trigone (yellow circle) is a small triangular area, lying behind last lower molar teeth on either side.
	Figure 6: Gingiva (arrows) is the tissue that covers the neck of the teeth and alveolar bone.
	Figure 7: Bony ridge that forms the borders of the upper and lower jaws and contains the sockets for teeth.
	Figure 8: Anterior two thirds of the tongue is the mobile part of the tongue. The dorsal surface is illustrated.
	Figures 9A and 9B: Filiform papillae appear as numerous, fine, pointed, cone-shaped papillae (blue arrow) and the fungiform papillae appear as mushroom-shaped reddish prominences on the dorsum of tongue (yellow arrow).
	Figure 10: Circumvallate papillae (arrows) appear as nodules (8-10 in number) on the posterior third of tongue.
	Figure 11: Foliate papillae of the tongue.
	Figure 12: Ventral surface of the tongue (yellow arrows), median lingual frenum (white arrow) and openings of the Wharton duct (blue arrows).
	Figure 13: The floor of mouth is a horseshoe-shaped area between the ventrum of the tongue medially and the gingivae of the lower teeth anteriorly and laterally, extending to the palatoglossal fold posteriorly.
	Figure 14: The hard palate (yellow arrows) forms the roof of the oral cavity and is continuous anteriorly with the maxillary alveolar arches and posteriorly with the soft palate (black arrow).