The lips are outer borders of the oral cavity. They are mobile muscular folders covered by the skin. It has only five layers. The skin is very thin, in comparison with the rest of the body where 16 layers are found. There are no hairs and no sweat glands. Lips serve as the opening for food intake, and air passageway, they are a tactile sensory organ because there are many nerve endings. They serve as creating different sounds as well.

Cheeks are the areas below the eyes and between the nose and the left or right ear. The space between the inside of the cheek and the teeth and gums is called the vestibule. The inside of the cheek is lined with a mucous membrane. The place contains the buccal nerve.

The tongue is a muscular organ. It is covered with moist, pink tissue – mucosa. The surface of the tongue has tiny bumps called papillae making it rough. The surfaces of the papillae are covered with thousands of taste buds. They are collections of nerves– like cells that connect to nerves running into the brain. We distinguish five common tastes: sweet, sour, bitter, salty and unami. Most taste buds on the tongue can detect umami taste. It has been described as savoury taste and first encounter is breast milk. It is also found in fish, shellfish, tomatoes, mushrooms, etc.

Two thirds of the tongue lie in the oral cavity, one third lies in the pharynx. The tongue is connected to the floor of the mouth by the lingual frenulum.

It is a part of digestive system. It helps with mixing food with saliva, moves food round in the oral cavity, it pushes the food towards pharynx when swallowing.

Its next function is articulation.

The palate, known as the roof of the mouth and floor of the nasal cavity, forms a division between the nasal cavity and oral cavity. It is composed of two parts, the bony hard palate, which is immovable and lies anteriorly, and the soft palate, made up of muscle fibres covered by a mucous membrane. It is movable, and it is elevated during swallowing upward to close nasopharynx. It prevents the fluid and food from entering the nasal cavity. There is an extension of this palate, called the uvula. It hangs down to the oropharynx, where are the tonsils at the back.

The salivary glands in human beings are glands that produce saliva. We have three major pairs of salivary glands and hundreds of minor salivary glands.

The parotid gland is located in the face. It produces serous saliva, a watery solution rich in enzymes, which helps with breaking down of food. It is secreted into the oral cavity near the second upper molar. The secreted volume of saliva is about 20-25% of secretion.

The sublingual glands are the smallest of the major glands. They lie on the floor of the oral cavity, under the tongue. They produce mixed secretions which are mainly mucous. They are important in keeping the oral mucosa moist, and in the beginning of the process of digestion.

The submandibular glands are located in the face. They produce mix of serous and mucous secretions, which helps with moistening of food, allow better swallowing and helps in digestion. The volume contributes around 70-75% of secretion.

Saliva is a fluid substance. Healthy person produces about 1-1, 5 litres of saliva per day. It is composed of 99. 5% water and various enzymes, mucus, white blood cells, epithelial cells, antimicrobial agents.

Saliva has several functions: