The oral cavity includes the lips, buccal mucosa, anterior tongue, floor of the mouth, hard palate, upper gingiva, and lower gingiva. The tongue occupies a major portion of the oral cavity and is contiguous with the floor of the mouth. The gingival mucosa overlying the mandibular and maxillary alveolar ridges adheres to the underlying periosteum. The hard palate forms the roof of the oral cavity and consists of mucosa overlying the palatine portion of the maxilla extending from the superior alveolar ridge to the junction with the soft palate.

The Pharynx

The pharynx is a musculomembranous tube extending from the skull base to the level of the sixth cervical vertebra, supported by overlapping constrictor muscles (superior, middle, and inferior) and other muscles arising from the styloid process and skull base.

The region of the oropharynx consists of a complex three-dimensional musculomembranous conduit communicating with the oral cavity anteriorly, the nasopharynx superiorly, and the hypopharynx/larynx inferiorly. It is divided into four sites of clinical importance (1) the tonsillar area, which makes up the major portion of the lateral pharyngeal wall and blends with the tongue base, soft palate, and retromolar trigone; (2) the tongue base; (3) the soft palate; and (4) the posterior pharyngeal wall. Innervation of the pharynx is via the pharyngeal plexus, with contributions from the glossopharyngeal (sensory) and vagus nerves (motor and sensory).

The hypopharynx is divided into three distinct regions: (1) the pyriform sinuses, (2) the posterior surface of the larynx (postcricoid area), and (3) the inferior, posterior, and lateral pharyngeal walls. The pyriform sinus (a recess) is a paired mucosal cul-de-sac lying lateral to each side of the larynx, bounded superiorly by the pharyngoepiglottic folds and inferiorly by the cricoid cartilage. The sinuses come together at the esophageal introitus and cervical esophagus at the level of C6.

The Larynx

The larynx consists of a mucosally covered cartilaginous framework (thyroid and cricoid cartilages) suspended from above from the hyoid bone by the thyrohyoid membrane and attached below to the trachea. The opening to the larynx is continuous with the pharyngeal airway. Unlike the rest of the pharynx, the mucosa of the larynx consists largely of columnar ciliated respiratory-type epithelium, although stratified squamous epithelium is found on the upper posterior epiglottis, aryepiglottic folds, and true vocal folds. It is important to note that while lymphatics in the upper larynx are extensive whereas they are sparse in the true vocal cords, or glottis.

The larynx is divided into three anatomic regions: the supraglottic larynx, the glottic larynx, and the subglottic larynx. The supraglottic larynx includes the epiglottis, aryepiglottic folds, laryngeal surface of the arytenoids, false vocal cords, and ventricles. The glottic larynx is derived from the tracheobronchial anlage and consists of both true vocal cords and the mucosa of the anterior and posterior commissures. It extends from the lateralmost apex of the laryngeal ventricle to 1 cm below the free edge of the vocal folds toward the cricoid. The subglottic larynx consists of the region bounded by the glottis above and the inferior border of the cricoid cartilage. Lymphatic supply to the subglottic larynx is extensive and bilateral. The infraglottic lymphatics drain to the cervical nodes through the cricothyroid membrane, while supraglottic lymphatics drain through the thyrohyoid membrane.

Nose and Paranasal Sinuses

The term “nose and paranasal sinuses” refers to that region of the aerodigestive tract that starts at the vestibule of the nose, which is covered by squamous epithelium, and moves posteriorly to the posterior choana where the nasopharynx begins. By definition, paranasal sinus malignancy does not include the nasopharynx unless by extension. It does include the paranasal sinuses, specifically, the maxillary, ethmoid, frontal, and sphenoid sinuses. While the most common malignancy of the nose and paranasal sinuses is SCC, the nose and paranasal sinuses pose a particular set of problems that deserve separate consideration. As a result, the topic of nose and paranasal sinus malignancy is covered in a later section.