Pharynx

The pharynx is a fibromuscular tubular structure that forms the common pathway for both the respiratory and digestive systems. It extends from the base of the skull to the level of the sixth cervical vertebra, where it continues as the oesophagus. Positioned posterior to the nasal cavity, oral cavity, and larynx, the pharynx plays important roles in respiration, swallowing, speech resonance, and immune defence.

Anatomically, the pharynx is divided into three regions: the nasopharynx, located posterior to the nasal cavity and primarily involved in air conduction; the oropharynx, situated posterior to the oral cavity and associated with swallowing and lymphoid tissue such as the palatine tonsils; and the laryngopharynx, which lies posterior to the larynx and directs food into the oesophagus while maintaining airway continuity.

The wall of the pharynx is composed of mucosa, fascia, and skeletal muscles arranged into circular constrictor muscles and longitudinal muscles that coordinate the process of deglutition. The pharynx also contains important lymphoid tissue collectively forming Waldeyer's ring (pharyngeal lymphoid ring), which contributes to immune surveillance at the entrances of the respiratory and gastrointestinal tracts.