General

The vestibule includes the mucosal surface of the lips, buccal mucosa, and buccal/lateral surfaces of the alveolar ridges. The remainder of the oral cavity includes the more medial structures, including the hard and soft palate, mobile tongue (anterior two-thirds), and the oral floor. The oral floor contains the sublingual salivary glands, and the openings of the submandibular ducts (Wharton′s ducts), draining the submandibular glands, are found throughout on either side of the midline. The frenulum attaches the anterior tongue to the midline oral floor. Minor salivary glands coat the oral cavity and pharynx.

Musculature

The vestibule includes the orbicularis oris, various levators and depressors, as well as the buccinator, all muscles of facial expression. Tongue musculature involves both intrinsic muscles and extrinsic muscles, including the genioglossus, hyoglossus, and styloglossus, all of which are innervated by the hypoglossal nerve.

Blood Supply

The lingual artery is the primary blood supply to the tongue. The facial artery, a branch of the external carotid, supplies the vestibule via the superior and inferior labial arteries. The greater and lesser palatine foramina in the lateral hard palate house the greater and lesser palatine arteries, branches of the maxillary artery.

Lymphatic Drainage

Facial lymphatics drain primarily to submental, submandibular, and facial nodes of level 1, while the anterior tongue lymphatics drain to upper jugular nodes of level 2, often bilaterally.

Nerve Supply

The hypoglossal nerve, cranial nerve (CN) XII, is the motor supply to the tongue. The lingual nerve (a branch of the mandibular nerve, CN V₃) provides sensation, and taste fibers of the chorda tympani, to the anterior two-thirds of the tongue; CNs IX and X innervate taste buds of the posterior tongue and the base of the epiglottis, respectively. The facial nerve (CN VII) is the motor supply to the orbicularis oris. General sensation to the buccal mucosa is via the second division of the trigeminal nerve (maxillary nerve, CN V₂).

Physiology

On average, 1,500 mL of saliva is produced daily from the parotid, sublingual, submandibular, and minor salivary glands.

Detailed swallowing physiology is beyond the scope of this handbook. Briefly, swallowing is divided into active and passive phases. The active phases include a preparatory phase that involves salivation and mastication, and a second oral phase that involves bolus propulsion posteriorly. In the passive phase, CNs IX and X control involuntary laryngeal protective mechanisms and peristalsis.

General

The pharynx extends from the skull base to the sixth cervical vertebra (C6) and is divided into the nasopharynx, superior to the palate; the oropharynx, extending from the palate to the hyoid and from the circumvallate papillae anteriorly; and the hypopharynx, inferior to the hyoid, including the piriform recesses, posterior wall, and postcricoid region ( Fig. 5.1 ).

The cervical esophagus extends inferiorly, and the laryngotracheal complex sits anteromedially. Waldeyer′s ring of lymphoid tissue includes the adenoids (pharyngeal tonsil) of the nasopharynx, the palatine tonsils of the oropharynx, and the lingual tonsil lining the base of the tongue. Taste buds and minor salivary glands exist in this region as well. The auditory tubes (eustachian tubes) open in the lateral nasopharynx.