The pharynx, which is the vertical, tubular passage extending from the base of the skull to the beginning of the esophagus, is in open communication with the nasal, oral, and laryngeal cavities. It is customarily considered to have three components: the nasopharynx (superior to the soft palate), the oropharynx (the area extending from the soft palate superiorly to the hyoid bone inferiorly), and the laryngopharynx (the region extending from the hyoid bone to the lower border of the cricoid cartilage).

The nasopharynx communicates with the auditory tubes (whose ostia open into its lateral wall) and with the nasal cavities (through the choanae). The pharyngeal tonsils (adenoids) are located on the posterior wall of the nasopharynx. The cavity of this portion of the pharynx is always patent and is the widest part of the pharynx.

The oropharynx, sometimes called the posterior pharynx, widely communicates anteriorly with the mouth, where the cavity faces the pharyngeal aspect of the tongue. The palatine tonsils are on the lateral wall between the anterior palatoglossal arch and the posterior palatopharyngeal arch. These lymphoid tissue masses, in conjunction with the pharyngeal tonsil in the nasopharynx and with lymphoid tissue on the pharyngeal part of the tongue (lingual tonsil), form Waldeyer’s ring. The oropharyngeal isthmus can be closed by approximation of the palatoglossal arches, accompanied by retraction of the tongue. This lingual movement also occludes the lumen of the oropharynx above the bolus during swallowing.

The laryngopharynx communicates anteriorly with the opening of the larynx. Lateral to the laryngeal aditus (inlet) on either side is an elongated fossa, the piriform recess. Inferiorly, the laryngopharynx is continuous with the esophagus. This junction is the narrowest part of the pharynx.

At the pharyngoesophageal junction, the pharyngeal musculature consists of the inferior pharyngeal constrictor, the thickest of the three pharyngeal constrictors. This muscle can be logically subdivided into a superior thyropharyngeus, whose fibers arise from the thyroid cartilage and are directed superomedially to insert on a posterior median raphe, and an inferior cricopharyngeus, whose fibers originate from the cricoid cartilage and pass horizontally to insert on the median raphe. During swallowing, contraction of the thyropharyngeus propels the bolus, whereas the cricopharyngeus acts as a sphincter. Failure of the cricopharyngeus to relax during swallowing can result in herniation of the mucosa between the two parts of the inferior constrictor (Zenker’s diverticulum; see Chapter 12), or a predisposition to perforation of the esophagus with the endoscope.

The esophagus, which begins at the lower border of the cricoid cartilage, is about 25 cm long. It descends through the neck and thorax just anterior to the vertebral bodies. It passes through the diaphragm at about the level of the tenth thoracic vertebra, and ends by opening into the cardia of the stomach at about the level of the eleventh thoracic vertebra. It lies in the median plane at its origin, but deviates slightly to the left until the root of the neck. At the root of the neck, it gradually deviates to the right so that, by the level of the fifth thoracic
vertebra, it is once again midline. At the seventh thoracic vertebra, it again deviates to the left, and ultimately turns anteriorly to pass through the esophageal hiatus of the diaphragm. The thoracic esophagus also has anterior and posterior curves that follow the curvature of the vertebral column. The intraabdominal esophagus turns sharply to the left to become continuous with the stomach.

The anatomic relationships of the esophagus are important. In the neck, the esophagus is posterior to the trachea and anterior to the cervical vertebra and the prevertebral muscles. Lateral to the cervical esophagus and trachea on both sides are the recurrent laryngeal nerve (in or near the tracheoesophageal groove), the common carotid artery, and the thyroid lobes. In the lower neck, the thoracic duct ascends to the left of the trachea. In the mediastinum, from superior to inferior, the esophagus has the following relationships.