BOUNDARIES OF THE HEAD AND NECK:
Netter Plate Number: 57

Oral Cavity
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 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.

Pharynx
The pharynx is a musculomembranous tube extending from the skull base to the cricoid cartilage, located at approximately the level of the sixth cervical vertebra.
The region of the oropharynx has the boundaries of the oral cavity anteriorly, the nasopharynx superiorly, and the hypopharynx/laryngopharynx inferiorly.
It is divided into four sites of clinical importance: (a) the tonsillar area; (b) the tongue base; (c) the soft palate (although the soft palate is not considered a part of either the oro or nasopharynx); and (d) the posterior pharyngeal wall.
The hypopharynx is divided into three distinct regions: the piriform sinuses, the posterior surface of the larynx (postcricoid area), and the inferior, posterior, and lateral pharyngeal walls. The piriform 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.

Larynx
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 extends from the fornix of the ventricles to include both true vocal cords and the mucosa of the anterior and posterior commissures extending 1 cm below the free edge of the vocal folds.
The subglottic larynx consists of the region from 1 cm inferior to the fornix of the ventricle to the inferior border of the cricoid cartilage at approximately the level of C6.