The pharynx is a funnel-shaped, fibromuscular tube that extends from the base of the skull to the cricoid cartilage, where the pharynx continues as the esophagus. The pharynx serves as a common pathway for food and air.
SUBDIVISIONS OF THE PHARYNX
The pharynx is classically divided into three regions based on location: the nasopharynx, oropharynx, and laryngopharynx (Figure 27-1A–C).
A. Regions of the pharynx. B. Sagittal section of the head. C. Posterior view of the pharynx (midsagittal incision through the pharyngeal constrictor muscles).
The nasopharynx is posterior to the nasal cavity and superior to the soft palate. During swallowing, the soft palate elevates and the pharyngeal wall contracts anteriorly to form a seal, preventing food from refluxing into the nasopharynx and nose. When we laugh, this sealing action can fail, and fluids that are being swallowed while we laugh can end up in the nasal cavity.
Choanae. Arched openings that enable communication between the nasal cavity and nasopharynx.
Auditory tubes (Pharyngotympanic/Eustachian tubes). Open into the lateral walls of the nasopharynx and communicate with the middle ear. The auditory tubes enable middle ear pressure to equalize with atmospheric pressure.
Pharyngeal tonsil (adenoids). Lymphatic tissue in the posterosuperior nasopharynx; traps and destroys pathogens that enter from the air (Figure 27-1B).
Tonsillitis. When the pharyngeal tonsils (adenoids) are infected and swollen, they can completely block airflow through the nasal cavity so that breathing through the nose requires an uncomfortable amount of effort. As a result, inhalation occurs through an open mouth. Surgical removal of the adenoids (adenoidectomy) may be necessary if infections, earaches, or breathing problems become chronic.▼
The oropharynx is the region of the pharynx located between the soft palate and the epiglottis, and communicates with the oral cavity.
Palatoglossal arches. Arches formed by the palatoglossal muscles; mark the boundary between the oral cavity anteriorly and the oropharynx posteriorly.
Palatine tonsils. Situated within the palatoglossal arches and are considered mucosa-associated lymphoid tissues (MALT for short). They help protect the body from the entry of infectious material through mucosal sites. As a consequence, palatine tonsils may result in frequent infections.
The laryngopharynx extends between the epiglottis and the cricoid cartilage, with the larynx forming the anterior wall. The laryngopharynx serves as a common passageway for food and air (Figure 27-1B and C). The laryngopharynx communicates: