Anatomy

There are three paired major salivary glands - the parotid gland, the submandibular gland and the sublingual gland - as well as a multitude of minor salivary glands (Figure 19.1).

The parotid gland is the largest, weighing between 15 and 30 g. It is roughly pyramidal in shape, lying in front of and below the ear in the space between anterior aspect of sternocleidomastoid and the ramus of the mandible, projecting anteriorly onto the external surface of the masseter muscle for a variable distance. The lateral surface lies just below the skin and is roughly triangular in shape with its base superiorly close to the zygomatic arch and its apex (or tail) in the upper part of the neck. Medially, the gland extends into the infratemporal fossa, where it is closely related to the pharynx, the carotid sheath and the styloid complex. It is traversed by the facial nerve, entering on the posteromedial surface at the stylomastoid foramen and running forwards to the anterior surface on the outer aspect of the mandible, dividing into five terminal branches within the gland. The duct, "Stenson's duct", runs anteriorly across masseter to pierce buccinator and open opposite the upper second molar tooth. Accessory parotid gland tissue may be present on the masseter between the duct and the zygomatic arch. The gland contains serous acinar components divided into lobules, varying amounts of fat with a few mucinous or sebaceous elements.

The submandibular gland weighs between 7 and 15 g and occupies most of the submandibular triangle. It straddles the posterior border of mylohyoid; the larger superficial lobe lies just deep to the skin near the angle of the mandible while the smaller deep lobe lies inside the mouth between the tongue, mandible and the sublingual gland. Posteromedially it is separated from the pharynx by the styloid complex, glossopharyngeal nerve and hypoglossal nerve. The duct, "Wharton's duct", begins as tiny branches in the superficial lobe and runs posteriorly, emerging from the anterior aspect of the deep lobe. It runs through the sublingual space to open into the anterior floor of mouth at the sublingual papilla. The lobules of the submandibular gland are populated mostly by serous cells with lesser mucinous elements.

The sublingual gland is the smallest of the major salivary glands and weighs between 1.5 and

4 g. It lies in the floor of mouth between the mucosa, mylohyoid, the mandible and its fellow on the other side. Numerous tiny ducts ("Rivinus' ducts") drain directly into the floor of mouth but there may also be a larger common sublingual duct ("Bartholin's duct") that drains into the submandibular duct near its opening. It is predominantly mucinous in type with lesser serous elements.

Hundreds of minor salivary glands are dispersed in the submucosal tissues throughout the mouth and oropharynx. They are not found in the anterior hard palate or the attached gingiva except in the retromolar regions of the mandible. Each minor gland measures between 1 and

5 mm in diameter and they are usually not palpable clinically except in the lips. Most are innominate but for two sets of glands in the tongue, namely the glands of von Ebner around the circumvallate papillae and the glands of Blandin and Nunn in the ventral surface near the tip. Most minor glands are mucinous in type although the glands of von Ebner are serous.

Similar glands are located in the nasal mucosa, nasopharynx, larynx and hypopharynx but are referred to as "accessory glands" rather than salivary glands.

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