Mouth – Tissue and Systems

Mouth – Tissue and Systems

This article describes the basic anatomy and function of the mouth region to better understand symptoms of mouth cancer and the possible impact it might have. The mouth is a very complex region that is composed of a vast array of related structures. Cancer of the oral cavity is among the most common cancers for adults in the United States, particularly among men. Cancer of this area makes up about 2-3% of all cancers in the United States.

Cancer of the mouth includes those of the lips, tongue, palate, pharynx and mucosal surfaces. These may also include those involving underlying bone or vascular structures. This article will focus on symptoms that might arise from cancers of the mucous membranes in the mouth given the vast array of possible disease in this region. The most common types of mouth cancer include:

  • Squamous cell cancer (well over half of tumors are this type, most common)
  • Adenocarcinoma
  • Lymphoma

The oral cavity is a combined part of both the respiratory tract and digestive pathway. This region generally starts at the border of the lips where skin and mucus membranes begin in the mouth known as the vermillion border. The mouth technically extends to the back of the tongue where the hard and soft palate interfaces. Beyond this region lower down the pharynx and hypopharynx continue (also commonly referred to as the throat). The floor of the mouth is a complex area that combines part of the tongue, underlying muscle and adjacent surfaces of the lips and cheek. About a third of mouth cancers are found on the lip. Many of these are related to risk factors such as smoking and excessive sun exposure. There is no “safe” amount of smoking and all smokers are at risk for this. The portion of the mouth that surrounds the teeth or gums and adjacent buccal mucosa is a frequent site for mouth cancer.

The oral cavity has a rich supply of lymphatics that drain into a complex array of adjacent lymph nodes. As our blood vessels supply our cells some fluid leaks out around the vessels and cells. Some fluid also collects with protein in these areas also. This extra-cellular fluid is collectively trapped by lymphatic vessels and transported back to the blood stream. The fluid is brought through checkpoints known as lymph nodes that screen and process the fluid to check for foreign invaders such as bacteria. This is an important part of the immune system of the body. A key feature of the mouth region is the incredibly rich lymphatic drainage and multiple lymph node packets that surround the neck. These lymph node packets are organized into 7 or 8 key groups that each help drain a specific region of the head and neck. The reason these are vitally important to understand is that if cancer of mouth spreads outside of its growth area, it is likely to spread via the lymphatic system and to adjacent lymph nodes. For example, a person with a small cancerous tumor of the lower lip that also has firm and enlarged lymph nodes in the same side of the neck nearby likely has advanced cancer.

One of the keys to understanding mouth cancer and normal health of the mouth is to understand who is at risk for cancer in this area. The majority of people with mouth cancer are men. This has to do with habits and lifestyle choices that tend to be more common in men. The smoker has an increased risk of mouth cancer by a factor greater than 15 times. Alcohol abuse more than doubles the risk as well. When a person smokes cigarettes and abuses alcohol, the risk is greatly increased more than either of them together. Areas of the world that have higher rates of mouth cancer tend to have a much higher rate of smoking and other injurious oral practices. Excessive sun exposure is also a risk factor for lip cancer.

There are certain infections that increase the risk of oral or head and neck cancer such as infection with the human papilloma virus (HPV). In fact, it is now believed that the increasing numbers of cases of cancer in the mouth and oral cavity is related to infection with HPV which occurs during oral sex. This is a modifiable risk factor. Abstinence and safe sexual practices such as condom use can reduce the risk.

There is now a vaccine available called Gardasil® that can prevent most cases of HPV that lead to cancer in the mouth as well as other areas. It is recommended for both teenage girls and boys. It is highly recommended that these vaccines be given before teenagers become sexually active. Men that have sex with men are at more risk, as are girls that engage in oral sex. It has not been FDA approved for this purpose yet, but is approved to prevent cervical, anal, vulvar, and vaginal cancer.

The general functions of the mouth include participation with breathing, helping to humidify air as it passes to the lungs and helping to screen or trap inhaled particulate matter. The mouth also functions to allow passage of food and regulate the passage of chewed food in an organized manner that coordinates with temporary closure of the airway. The mouth also plays vital social function as it portrays one’s health and cleanliness to others as well as assists in communication and speech patterns. Nutrition and taste both for survival and pleasure is an important function as well. It is easy to see how a cancer in this area may well impact many parts of a person’s life.

Abnormality of the mouth should prompt notification of your doctor for further investigation. Many tumors or growths of the mouth are not cancer and testing with biopsy is the usual mechanism to distinguish these. Most oral cancers are quite treatable and the best outcome is obtained by early detection and prompt treatment. Treatment of oral cancer has a large spectrum from topical ablation and very minor surgery to those more radical treatments including head and neck radiation with partial removal of the lung or one side of the neck lymph nodes.


  3. Townsend Jr, CM; Beauchamp RD; Evers BM; Mattox KL. (2008) Townsend: Sabiston Textbook of Surgery, 18th ed. Chapter 33. New York, NY: Saunders.
  4. Goldman L, Schafer, AI; (2011) Goldman: Goldman’s Cecil Medicine, 24th ed. Chapter 196. New York, NY: Elsevier
  6. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.