The oral cavity is a defined anatomical section of the head. The inner surfaces of the lips and cheeks are part of it, as are the gums, teeth, anterior palate, floor of the mouth, and tongue. The entire oral cavity is lined with mucosa, consisting of so-called multilayered, nonkeratinizing squamous epithelium.
What is the oral cavity?
The oral cavity is defined as the first section of the human digestive tract. As part of the mouth, the oral cavity contains relevant organs, tongue and teeth, which are responsible for the comminution of ingested food. Histologically, the mucosal epithelium of the oral cavity consists of Merkel cells, Langerhans cells and melanocytes, as they are also found in the skin. Beneath the epithelium of the oral cavity is a layer of tissue, lamina propria, which is interdigitated with the epithelium in a papilla-like fashion. In addition, the lamina propria has adhesions with the periosteum of the palate. The oral cavity is a body orifice for food intake; the tongue and teeth provide initial shaping and comminution of the supplied food components. Formation, mixing and comminution result in the so-called food bolus. While still in the oral cavity, this food bolus is mixed with digestive enzymes and viscous secretions that originate from the salivary glands. The salivary glands release their digestive juices directly into the oral cavity via tiny excretory ducts. The oral cavity is also involved in the processes of making facial expressions, breathing and voice production. The entire mouth is not a sterile region of the body, but is colonized by a multitude of germs and microorganisms. The totality of all germs found in the oral cavity is also referred to as oral flora. These are predominantly harmless saprophytes. However, the oral flora can also harbor facultative or obligate pathogenic germs, which, however, are not dangerous for the carrier if the immune system is intact. If there are shifts in the physiological balance in the oral cavity, then pathogenic germs can quickly gain the upper hand and trigger various diseases, including caries, aphthae or inflammation of the oral mucosa.
Anatomy and structure
The oral cavity can be anatomically divided into 3 sections, the oral vestibule, the oral cavity, and the pharyngeal fossa. The oral vestibule, vestibulum oris, is the area between the cheeks and teeth. The main oral cavity, cavum oris proprium, is bounded laterally and anteriorly by the so-called alveolar processes and the teeth located therein. The transition from the oral cavity to the pharyngeal region is called the pharyngeal fossa, isthmus faucium. The tongue is attached to the floor of the mouth and occupies most of the main oral cavity. The floor of the mouth contains the sublingual glands, glandulae sublingualis. From the alveolar processes, the rows of teeth of both jaws project far into the oral cavity and surround the tongue in a horseshoe shape. The multilayered unkeratinized squamous epithelium of the oral cavity has a high regenerative capacity. Defects caused by inflammation or injury can thus be repaired within 4 to 10 days without any consequences. However, the high mitotic rate of the oral mucosa also makes it susceptible to cell proliferation, including the development of malignant tumors.
Function and tasks
The oral cavity performs a variety of functions, as the beginning of the digestive tract, the oral cavity is also called the head intestine. This is because, strictly speaking, digestion begins directly in the mouth immediately after food intake. Teeth hold a bite and grind and crush it. The oral mucosa contains proprioceptors and sensors that serve to test food, regardless of whether it is supplied in solid or liquid form. These receptors are able to check the temperature and consistency of food components at lightning speed due to their fine sensitivity. Taste buds are located on the roof of the throat and in the pharynx, but there are particularly many of them on the surface of the tongue. These receptors can make a rough classification into the 4 tastes sweet, sour, salty and bitter. Bitter receptors are located primarily at the back of the tongue just before the entrance to the pharynx. In close cooperation with the sense of smell, the taste buds form the human sense of taste. Speech and sound formation are also important functions of the oral cavity. Externally, the oral cavity also serves to communicate with the environment through the mimic musculature.
Diseases and ailments
Among the most common clinical pictures of the oral cavity with corresponding functional limitations are inflammations of the oral mucosa, which can be triggered by an imbalance of the bacterial flora. Poor oral hygiene or incorrect mechanical stress, for example due to ill-fitting dentures, can promote inflammation of the gums or oral mucosa. Inflammations, for example in the form of painful aphthae of the oral cavity, can be manifested by pain and redness of the oral mucosa and tongue, vesicles or whitish coatings, ulceration and abscesses or burning, increased salivation and bad breath. Diseases of the oral cavity, such as harelip, can also be congenital. From a certain extent, such congenital defects can be surgically repaired. Malignant neoplasms in the area of the oral cavity are still feared today, as they hardly cause any discomfort at the beginning. If patients present themselves in dental practices or to ENT physicians because of whitish, painless changes in the mucous membrane, many of the cases are already advanced tumor stages. The most common type of malignant tumor of the oral cavity is tongue cancer and cancer of the sublingual gland, also known as oral floor cancer. Early detection can only be achieved through consistent specialist assessment of the entire oral and pharyngeal cavity as part of screening examinations. Alcohol and nicotine use can significantly increase the risk of any type of oral cavity cancer.
