Most head and neck cancers begin in the squamous cells that line the structures found in the head and neck. Squamous cells are flat cells that cover inside and outside surfaces of the body.

Cancers of the head and neck are further identified by the area in which they begin:

Oral cavity – this includes the lips, the front two-thirds of the tongue, the gums, the lining inside the cheeks and lips, the floor of the mouth under the tongue, the bony top of the mouth (hard palate), and the small area behind the wisdom teeth.

Salivary glands – these are located in several places: under the tongue, in front of the ears and under the jawbone, as well as in other parts of the upper digestive tract.

Paranasal sinuses and nasal cavity – the paranasal sinuses are small hollow spaces in the bones of the head surrounding the nose. The nasal cavity is the hollow space inside the nose.

Pharynx – this is a hollow tube about five inches long that starts behind the nose and leads to the esophagus and trachea. The pharynx has three parts:

Nasopharynx is the upper part of the pharynx behind the nose.

Oropharynx is the middle part of the pharynx that includes the soft palate (the back of the mouth), the base of the tongue, and the tonsils.

Hypopharynx is the lower part of the pharynx.

Larynx – also called the voice box, is a short passageway formed by cartilage just below the pharynx in the neck. The larynx contains the vocal cords. It also has a small piece of tissue, the epiglottis, which moves to cover the larynx to prevent food from entering the air passages.

Lymph nodes in the upper part of the neck – sometimes squamous cancer cells are found in the lymph nodes of the upper neck. They may be associated with one of the above sites. They may also be found when there is no evidence of cancer in other parts of the head and neck and this is called an unknown primary.