The salivary glands make saliva and release it into the mouth. There are three pairs of relatively large, major salivary glands:
Parotid glands are located in the upper part of each cheek, close to the ear. The duct of each parotid gland empties onto the inside of the cheek, near the molars (back teeth) of the upper jaw.
Submandibular glands, in the floor of the mouth, have ducts that empty behind the lower front teeth.
Sublingual glands, beneath the tongue, have ducts that empty onto the floor of the mouth.
In addition to these major glands, 600 to 1,000 very tiny, minor salivary glands are scattered throughout the mouth and throat. They lie under the moist skin that lines the inner lips, inner cheeks, palate, back of the throat, back portion of the tongue, pharynx and sinuses.
Some of the most common salivary gland disorders include:
Sialolithiasis (salivary gland stones) – Tiny, calcium-rich stones, called sialoliths or salivary calculi, sometimes form inside the salivary glands. Although the exact cause of these stones is unknown, some stones may be related to dehydration, which thickens the saliva; decreased food intake, which lowers the demand for saliva; or medications that decrease saliva production, including certain antihistamines, blood pressure drugs and psychiatric medications. Some stones sit inside the gland without causing any symptoms. In other cases, a stone blocks the gland's duct, either partially or completely. When this happens, the gland typically is painful and swollen, and saliva flow is partially or completely blocked. This can be followed by an infection called sialadenitis.
Sialadenitis (bacterial infection of a salivary gland) – Sialadenitis is a painful infection that usually is caused by staphylococcus, streptococcus, Haemophilus influenzae or anaerobic bacteria. Although it is very common among elderly adults with salivary gland stones, sialadenitis also can occur in infants during the first few weeks of life. Many things increase the risk of this condition, including dehydration, recent surgery, prematurity, malnutrition, eating disorders, chronic illness, cancer, medications (antihistamines, diuretics, psychiatric medications, beta-blockers, barbiturates), Sjgren's syndrome and certain occupations (trumpet playing, glass blowing). Without proper treatment, sialadenitis can develop into a severe infection, especially in people who are debilitated or elderly.
Viral infections – Systemic (whole-body) viral infections sometimes settle in the salivary glands, causing facial swelling, pain and difficulty eating. The most common example is mumps. Similar symptoms can be caused by other viral illnesses, including flu, parainfluenza, Coxsackie viruses, echovirus and cytomegalovirus.
Cysts (tiny fluid-filled sacs) – Babies sometimes are born with cysts in the parotid gland because of problems related to ear development before birth. Later in life, other types of cysts can form in the major or minor salivary glands as a result of traumatic injuries, infections, or salivary gland stones or tumors. One of the most common types is a mucocele, a mucus-filled cyst that often occurs inside the lower lip.
Benign tumors (noncancerous tumors) – About 80 percent of all salivary gland tumors occur in the parotid gland, and the majority are benign (noncancerous). The most common type of benign parotid tumor, a pleomorphic adenoma, usually appears as a slow-growing, painless lump at the back of the jaw, just below the earlobe. More than 95 percent of all benign salivary gland tumors occur in adults. Risk factors include radiation exposure and possibly smoking.
Malignant tumors (cancerous tumors) – Salivary gland cancers are rare and most often occur in people between the ages of 50 and 60. They can be either low-grade (less aggressive) tumor or a high-grade (more aggressive) tumor. The only known risk factors for salivary gland cancers are Sjgren's syndrome and exposure to radiation, although smoking also may play some role.
Sjgren's syndrome – Sjgren's syndrome is a chronic autoimmune disorder in which the body's immune defenses attack the salivary glands, the lacrimal glands (glands that produce tears), and occasionally the skin's sweat and oil glands. In some cases, the illness also affects the lungs, liver, vagina, pancreas, kidneys and brain. Most people with this disease are women who first develop symptoms during middle age. In about 50 percent of cases, the illness occurs together with rheumatoid arthritis, systemic lupus erythematosus (lupus), scleroderma or polymyositis.
Sialadenosis (nonspecific salivary gland enlargement) – Sometimes, the salivary glands become enlarged without evidence of infection, inflammation or tumor. This nonspecific enlargement, called sialadenosis, most often affects the parotid gland, and its cause remains unknown. Sialadenosis may develop in people who are obese, in women who are pregnant or breastfeeding, and in people with malnutrition, eating disorders, alcoholic cirrhosis, kidney failure, thyroid problems or other illnesses.
From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.
