mouth. Keratinised masticatory mucosa is tightly bound to the hard palate and gingivae. It accounts for 25% of all oral mucosa. It supports underlying tissues by resisting the loading forces exerted during mastication. Lining mucosa in the cheeks, lips and floor of mouth is mobile to create space when chewing and talking. During mastication, it allows food to move freely around the mouth and physically protects the underlying tissues from trauma. It accounts for 60% of oral mucosa. Secretion - Saliva is the primary secretion of the oral mucosa. It has many functions including lubrication, pH buffering and immunity. The lubricating and antimicrobial functions of saliva are maintained mainly by resting; saliva results in a flushing effect and the clearance of oral debris and noxious agents. Saliva contains numerous antimicrobial proteins that help protect the oral ecosystem from infectious agent. The components like lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, and thiocyanate concentrations act as a defense mechanism in the saliva. Saliva is secreted from 3 pairs of major salivary glands (parotid, submandibular, sublingual) alongside many minor salivary glands. It also aids the initial chemical digestion of food as it contains the enzyme amylase, responsible for breaking carbohydrates into sugars. Sensation - The oral mucosa is richly innervated, meaning it is a very good at sensing pain, touch, temperature and taste. A number of cranial nerves are involved in sensations in the mouth including trigeminal (V), Facial (VII), glossopharyngeal (IX) and Vagus (X) nerves. The dorsum of the tongue is covered in specialised mucosa. This contains the presence of taste buds allowing taste, and it accounts for around 15% of oral mucosa. Reflexes such as swallowing, gagging and thirst are also initiated in the mouth. Thermal regulation - Although not significant in humans, some animals e.g. dogs rely on panting to regulate their temperature, as sweat glands are only present in their paws Clinical significance Infective Viral The majority of viral infections affecting the oral cavity are caused by the human Herpes Virus group. Each human herpes virus may present differently within the oral cavity. They are more likely to affect immunocompromised patients such as children and the elderly. Herpetic Gingivostomatitis: A self-limiting viral infection which is caused by Herpes Simplex Virus-1(HSV-1). It usually presents in young children and is very contagious . It is characterised by the presence of small oral blisters which break down and coalesce into ulcers Herpes Labialis