Svelget

Svelget, or the pharynx, is a muscular tube located at the back of the nasal and oral cavities. It forms part of both the respiratory and digestive systems, serving as a common passageway for air and food. It extends from the base of the skull to the upper esophagus at the level of the cricoid cartilage.

Anatomy: The pharynx is divided into three regions: the nasopharynx (behind the nasal cavity), the oropharynx (behind the oral cavity), and the laryngopharynx or hypopharynx (behind the larynx). The nasopharynx contains the pharyngeal tonsil and the openings of the pharyngotympanic (Eustachian) tubes. The oropharynx houses the palatine and lingual tonsils. The pharyngeal wall is reinforced by the three pharyngeal constrictor muscles (superior, middle, inferior) which contract in sequence to move a bolus toward the esophagus during swallowing.

Function: The pharynx serves both respiration and digestion. It channels air from the nasal and oral cavities to the larynx and lungs, and food from the oral cavity to the esophagus. During swallowing, coordinated movements and airway protection prevent aspiration, while the soft palate elevates to seal the nasopharynx.

Innervation and circulation: The pharynx receives motor and sensory fibers from the pharyngeal plexus, largely via the glossopharyngeal (IX) and vagus (X) nerves. Blood supply comes from branches of the external carotid system, notably the ascending pharyngeal artery and tonsillar branches; venous drainage flows into the pharyngeal venous plexus and then the internal jugular vein.

Clinical notes: Pharyngitis (sore throat) is common. In children, hypertrophy of the pharyngeal tonsils (adenoids) can cause nasal obstruction. The nasopharynx is also a site of certain cancers in some populations.

See also: Larynx, Esophagus, Nasopharynx.