The pharynx, also known as the throat, is a passageway or tube that leads from the nasal and oral cavities to the larynx (voice box) and esophagus at the level of the 6th cervical vertebrae. It consists of 3 parts, the nasopharynx, the oropharynx, and the laryngopharynx.
Nasopharynx
The nasopharynx is the region of the pharynx between the base of the skull and the soft palate. It helps with respiration by conditioning and propagating the inspired air into the larynx. The region is lined by respiratory epithelium which protects and moistens the airways. Adenoid tonsils are present in the posterior part of the nasopharynx. These tonsils enlarge between 3-8 years of age and thereafter start regressing.
Oropharynx
The oropharynx is the middle region of the pharynx between the soft palate and upper part of the epiglottis, which is a flap of cartilage located behind the tongue. The oropharynx contains the posterior one-third of the tongue, the lingual and palatine tonsils, and the superior pharyngeal constrictor muscle. The oropharynx plays a role in the involuntary and voluntary phases of swallowing.
Laryngopharynx
The laryngopharynx is the lowest region of the pharynx. It is located behind the larynx between the epiglottis and the sixth cervical vertebrae. The middle and inferior pharyngeal muscles are present in this region.
Muscles of Pharynx
The pharynx is made of longitudinal and circular muscles. The longitudinal muscles are the stylopharyngeus, the palatopharyngeus, and the salpingopharyngeus. These muscles shorten and widen the pharynx and lift the larynx during the act of swallowing. The circular muscles are the superior, middle, and inferior pharyngeal constrictors. They help propel food from the mouth into the esophagus by constricting sequentially.
Nerve Supply of the Pharynx
The sensory and motor nerve supply of the pharynx is mainly from a group of nerves called the pharyngeal plexus which overlies the middle pharyngeal constrictor muscle.
Vasculature of the Pharynx
The pharynx receives its blood supply from the external carotid artery and venous drainage is by the pharyngeal venous plexus which in turn drains into the internal jugular vein.
