Diseases of the Salivary Glands

1

Describe the histology of the salivary gland secretory unit.

From proximal to distal: Acinar cells –> intercalated duct –> striated duct –> excretory duct. Contractile myoepithelial cells surround the acini and intercalated ducts ( Fig. 15.1 ).

2

What volume of saliva is produced daily? When is each salivary gland most active?

Approximately 1500 mL of saliva is produced daily. At rest, the submandibular glands are the most active (producing two-thirds of all saliva). When stimulated by nausea, food, olfaction, or mastication, the parotid glands become the most active.

3

Describe the anatomic boundaries, vascular anatomy, and parasympathetic innervation of the parotid gland.

The parotid gland ( Fig. 15.2 ) is located in the lateral face (parotid space), bordered by the masseter muscle anteriorly/medially, the zygomatic arch superiorly, the tragal cartilage posteriorly, the angle/ramus of the mandible posteriorly/medially, and the sternocleidomastoid muscle (SCM) inferiorly. It is enveloped by the parotidomasseteric fascia, a continuation of the superficial layer of the deep cervical fascia.

The external carotid artery lies medial to the parotid and branches into the maxillary and superficial temporal arteries. Venous anatomy is variable: the maxillary and superficial temporal veins form the retromandibular vein and join the external jugular vein.

Parasympathetic innervation: inferior salivatory nucleus –> glossopharyngeal nerve (CN IX) –> Jacobson’s nerve –> lesser petrosal nerve –> otic ganglion –> auriculotemporal nerve.

4

What is the name and course of the parotid duct?

Stensen’s duct travels superficial to the masseter, pierces the buccinator muscle, and enters the oral cavity opposite the second maxillary molar. The duct is approximately 1.5 centimeters inferior to the zygoma.

5

What divides the parotid into superficial and deep portions anatomically and radiographically?

The facial nerve separates the parotid into superficial and deep lobes (not a true fascial plane). The retromandibular vein is a surrogate radiographic landmark for the facial nerve.

6

Describe the anatomic boundaries, vascular anatomy, and parasympathetic innervation of the submandibular gland.

The submandibular gland ( Fig. 15.3 ) is inferior and deep to the mandible in the submandibular triangle (defined by the anterior and posterior bellies of the digastric muscle and the mandibular body). The mylohyoid muscle divides the gland into superficial and deep lobes. In the surgical field from the neck, retraction of the mylohyoid muscle reveals the lingual nerve, Wharton’s duct (submandibular duct), and hypoglossal nerve lying superficial to the hyoglossus muscle.

The facial artery travels obliquely and deep to the posterior belly of the digastric muscle along the posterior surface of the submandibular gland. The facial artery curves over the mandible body at the superior aspect of the gland. The facial vein travels anterior to the gland.

Parasympathetic innervation: superior salivatory nucleus –> nervus intermedius –> chorda tympani –> submandibular ganglion –> lingual nerve.

7

Describe the anatomy, parasympathetic innervation, and ducts of the sublingual gland.

The sublingual gland ( Fig. 15.4 ) is located adjacent to the lingual frenulum, lateral to the genioglossus and geniohyoid muscles, and superficial to the mylohyoid muscle. The blood supply is from the branches of the facial and lingual arteries. Parasympathetic innervation is the same as for the submandibular gland. The sublingual gland drains into the oral cavity through the ducts of Rivinus or into Wharton’s duct via the Bartholin duct.

8

What is the most common bacteria in acute suppurative sialadenitis? How is it treated?

Staphylococcus aureus is the most common bacteria that causes sialadenitis. Treatment consists of antibiotics effective against β-lactamase-producing bacteria (i.e., amoxicillin-clavulanate) or culture-directed antibiotics plus hydration, warm compresses, gland massage, and sialagogues.

9

Sialolithiasis affects which salivary gland primarily? List available treatment options.

The submandibular gland is most affected by sialolithiasis due to the more viscous/mucinous saliva that travels superiorly against gravity in Wharton’s duct. Treatment options include the following:

• 1.

  Conservative management with sialagogues, warm compresses, antibiotics, massage, and hydration

• 2.

  Open sialolithotomy

• 3.

  Sialendoscopy (<6 millimeter sialoliths)

• 4.

  Lithotripsy

• 5.

  Excision of salivary gland

10

What is the most common viral infection of the parotid?

Mumps is still the most common cause of viral parotitis, although most infections have been eliminated by vaccination.

11