A. Anatomy and physiology
The major salivary glands include the parotid, submandibular, and sublingual glands. Hundreds of minor salivary glands exist in the palate, oral mucosa, and tongue. Salivary glands supply 1 to 1.5 L of saliva per day. Saliva provides lubrication during mastication, inhibits bacterial growth, helps to maintain dental health, and contains some digestive enzymes.
- The parotid gland is the largest of the salivary glands. Its secretions are primarily serous, and it is the dominant producer of saliva during mastication. It lies anterior to the ear on the surface of the masseter muscle. The parotid duct (Stensen’s duct) empties into the oral cavity adjacent to the second maxillary molar. The facial nerve (CN VII) travels through the parotid gland.
- The submandibular gland lies inferomedial to the mandible. It produces a mixture of mucinous and serous saliva. The submandibular duct (Wharton’s duct) empties into the floor of the mouth just lateral to the lingual frenulum.
- The sublingual gland lies below the floor of the mouth mucosa. Its multiple ducts empty directly into the floor of the mouth and secrete primarily mucinous saliva.
B. Inflammatory diseases of the salivary glands
- Acute sialadenitis is a bacterial inflammation of the salivary glands, usually involving the parotid gland. It occurs from retrograde bacterial contamination from the oral cavity due to salivary stasis. It is more common in elderly, diabetic, immunocompromised, or dehydrated individuals. Treatment includes hydration, antibiotics, and sialogogues (agents that increase the flow of saliva, such as lemon drops). Surgical drainage is rarely needed.
- Chronic sialadenitis is caused by recurrent episodes of salivary gland inflammation. The gland becomes fibrotic and firm, and treatment is surgical resection of the gland.
- Mumps is caused by paramyxovirus and results in acute parotitis. Treatment of parotitis involves supportive measures. Due to widespread vaccinations, the incidence of mumps is low in the United States.
- Sialolithiasis most frequently affects the submandibular gland. Calculi consist of organic and crystalline components, which cause glandular swelling and pain prior to eating. Calculi can be diagnosed by palpation or radiography. Ductal calculus may be removed transorally using probing instruments, whereas parenchymal calculi require surgical removal of the gland.
Facial lacerations can involve the parotid parenchyma, Stensen’s duct, and branches of the facial nerve. Loss of facial function mandates exploration and epineural repair of the nerve. Injury to the parotid duct requires repair of the duct over a stent.