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Anatomy Presentation – Structures involved in swallowing
The hypopharynx is the lower portion of the pharynx. It is also known as the laryngopharynx.
There are three pharyngeal recesses: Food boluses can lodge in these recesses.
The vallecula is the space or depression between the base of the tongue and the epiglottis.
The two pyriform sinuses are located in the pharynx, beside the larynx. They are formed by the shape of muscle attachments to the pharyngeal walls.
The superior, middle, and inferior pharyngeal constrictor muscles make up the external circular layer of the pharynx.
The stylopharyngus m. and the salpingopharyngus m. make up the internal longitudinal layer of the pharynx.
The pharyngeal constrictor muscles help move food down toward the esophagus via a stripping action. (This process should not be confused with peristalsis which is the wave-like motions of muscles that occur in the esophagus. In some of the literature the action of the pharyngeal constrictor muscles is mistakenly called peristalsis.)
The latest research on swallowing suggests that the action of the pharyngeal constrictor muscles is not the most critical factor in the movement of food down the pharynx. It seems that the plunger action of the tongue, or the tongue driving force, plays a major role in this process.
The cricopharyngus m. or pharyngeal-esophageal (P.E) segment separates the pharynx from the esophagus. At the end of the pharyngeal stage of the swallow, it must relax to allow the bolus to enter the esophagus. (It is normally closed to prevent the reflux of food and to keep air out of the digestive system.) If the P.E. segment does not relax, food will build up in the pharynx and eventually spill over the top of the larynx into the airway. The cricopharyngus is innervated by the vagus (CN. X).
Problems with the P.E. segment are rare. According to Logemann (1983, 1989), only 5% of dysphagias are caused by malfunction of the...
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