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Salivary GlandsEdit

The salivary glands are a set of exocrine glands in the mouth and surrounding structures that produce saliva, a digestive and protective fluid essential for oral health. Saliva moistens food, begins the breakdown of starches, buffers acids, and helps cleanse the mouth. Beyond digestion, saliva contains immune factors and enzymes that reduce the risk of tooth decay and infection, and it supports the comfort and function of the tongue, lips, and palate. The system operates under autonomic control, adjusting secretion in response to eating, hydration, and other bodily states.

There are three major pairs of salivary glands and many smaller glands embedded in the mucosa of the mouth and throat. The major glands are the parotid gland, the submandibular gland, and the sublingual gland. The minor salivary glands are distributed throughout theoral mucosa—including the lips, cheeks, palate, and tongue—and contribute a steady baseline flow of saliva that keeps the mouth moist even between meals.

Anatomy and physiology

  • Major glands

    • The parotid glands sit near the jawline, anterior to the ears, and predominantly secrete serous (watery) saliva rich in enzymes such as amylase, which begins starch digestion.
    • The submandibular glands lie beneath the lower jaw and produce a mixed, predominantly serous secretion with significant mucin, contributing to lubrication and digestion.
    • The sublingual glands reside under the floor of the mouth and secrete mucous-rich saliva, providing lubrication and protection for the tongue and oral tissues.

  • Minor glands

    • The numerous small glands distributed along the mucosa supply a continuous baseline secretion that maintains moisture, protects the mucosal surface, and supports taste and swallowing.

  • Composition and function of saliva

    • Saliva is a water-based fluid containing electrolytes, mucus, and enzymes such as amylase. It also contains antimicrobial proteins and immunoglobulins (notably IgA) that contribute to oral immune defense.
    • The amount and composition of saliva adapt to conditions such as hydration, circadian rhythms, and exposure to food.

  • Regulation of secretion

    • Parasympathetic stimulation typically increases watery saliva production, aiding digestion and lubrication.
    • Sympathetic input tends to produce a smaller volume of more viscous saliva, which still helps with lubrication but may influence taste perception and mouthfeel.

  • Ducts and drainage

    • The major glands drain via specific ducts:
    • The parotid gland releases saliva through the Stensen's duct (the parotid duct) into the mouth near the upper second molar.
    • The submandibular glands drain via the Wharton's duct (the submandibular duct) toward the floor of the mouth.
    • The sublingual glands release saliva through multiple small ducts, often referred to as Bartholin's ducts.
    • Minor glands drain directly into the oral cavity through small ducts scattered across the mucosa.

Clinical aspects

  • Common conditions

    • Sialolithiasis is the formation of calcified stones that can block salivary ducts, most often in the submandibular gland and causing pain and swelling with meals.
    • Infections or inflammation of the glands, including viral parotitis, can impair saliva production and lengthen recovery time.
    • Tumors of the salivary glands can be benign or malignant. The most common benign tumor is the pleomorphic adenoma, while the Warthin's tumor is another notable benign neoplasm; malignant tumors are less common but require prompt evaluation.

  • Systemic and autoimmune influences

    • Conditions such as Sjogren's syndrome can markedly reduce saliva production, leading to dry mouth, increased risk of dental caries, and discomfort.
    • Medication use, dehydration, radiation therapy to the head and neck, and systemic illnesses can all influence salivary output and composition.

  • Diagnostics and treatment

    • Evaluation may include physical examination, imaging (for example, ultrasound, CT, or MRI), and targeted imaging of the ducts (sialography) when ductal disease is suspected.
    • Treatments range from conservative approaches—hydration, sialogogues (agents that stimulate saliva flow), and oral hygiene measures—to procedural interventions for stones or tumors. Surgical removal of affected glands or ducts may be necessary for certain conditions, and cancer treatment sometimes requires multidisciplinary care.

  • Public health and lifestyle considerations

    • Adequate hydration, good oral hygiene, fluoride exposure, and limiting substances that dry the mouth (where appropriate) support saliva function and dental health.
    • Vaccination against diseases such as mumps has reduced incidences of viral parotitis and its complications in many populations, illustrating how public health measures can influence gland-related illnesses.

See also