Читать книгу The Esophagus - Группа авторов - Страница 152

The pharynx is a tube composed of skeletal muscle lined by squamous epithelium [1] (Figure 6.1). The oropharynx (mesopharynx) is the portion of the pharynx associated with the oral cavity. The oropharynx extends craniocaudally from the soft palate to the pharyngoepiglottic fold. The base of the tongue forms the anterior wall of the oropharynx; the posterior wall of the oropharynx abuts the upper cervical spine. The laryngopharynx (hypopharynx) is the portion of the pharynx associated with the larynx. The hypopharynx extends craniocaudally from the pharyngoepiglottic fold to the pharyngoesophageal segment [1]. The nasopharynx is the part of the pharynx associated with the nasal cavity. It participates primarily in breathing and is not considered in this chapter. The anatomy and physiology of the oral and pharyngeal cavity is complex. Refer to references 1–12 for a detailed discussion of pharyngeal anatomy and physiology.

The anterior wall of the hypopharynx is shaped by the larynx; its epiglottic and arytenoid cartilages contribute to the anterior wall of the hypopharynx [2] (Figures 6.2 and 6.3). The remainder of the anterior pharyngeal wall is formed by the piriform sinuses and surrounding thyroid cartilage. The posterior wall of the hypopharynx is bordered by the lower cervical spine. The junction of the pharynx and esophagus, the pharyngoesophageal segment, is lined by squamous epithelium and formed by the cricopharyngeus muscle. The pharyngoesophageal segment lies posterior to the cricoid cartilage.

The oropharynx and hypopharynx have four openings: superiorly, the velopharyngeal portal to the nasopharynx; anteriorly, the palatoglossal isthmus to the oral cavity; anteriorly, the laryngeal aditus to the larynx; and inferiorly, the pharyngoesophageal segment to the esophagus [1]. Thus, the pharynx is the crossroads of speech, respiration, and swallowing.

The palatine fossae are bounded by the anterior and posterior tonsillar pillars, also known as the paired palatoglossal and palatopharyngeal folds. The vertical surface of the tongue is nodular because of the underlying circumvallate papillae and lingual tonsil [2]. The valleculae are potential spaces created by a fold of tissue that extends posteriorly to the epiglottis (the median glossoepiglottic fold). The valleculae disappear when the epiglottis inverts during swallowing.

Figure 6.1 Normal pharynx. (A) Frontal view of the pharynx. The surface of the tongue (T) has a reticular appearance due to underlying lingual tonsil. The right tonsillar fossa (black arrowhead), right vallecula (V), tip of the left piriform sinus (white arrowhead), and several of the circumvallate papillae (black arrows) are all identified. The right lateral wall of the hypopharynx is identified with a thick arrow. (B) Lateral view of the pharynx during phonation. The soft palate (s) elevates to appose the posterior pharyngeal wall. The uvula (u) of the soft palate bows anteriorly. The palatopharyngeal fold (posterior tonsillar pillar) (long black arrow) overlies the palatopharyngeal muscle. The palatine tonsils (t) have barium trapped within their interstices. The vertical surface (base) of the tongue (T), epiglottic tip (e), valleculae (v), and tips of the piriform sinuses (p) are identified. The hyoid bone (h) is barely visible. The pharyngoesophageal segment (short black arrow) is closed.

Source: Reproduced from Rubesin SE, Jones B, Donner MW. Contrast pharyngography: the importance of phonation. Am J Roentgenol1987; 148:269–272, with permission

Figure 6.2 Folds of the epiglottis in a patient with radiation change. (A) Frontal view of the pharynx. The median glossoepiglottic fold (large arrow) divides the space between the base of the tongue and tip of the epiglottis (e) into two halves. The pharyngoepiglottic folds overlying the paired stylopharyngeal muscles course from the lateral pharyngeal wall to the lateral edge of the epiglottis (right pharyngoepiglottic fold identified with small arrows, forming the posterior wall of the valleculae. The lateral wall of each vallecula is formed by the lateral glossoepiglottic fold. The lowest portion of the right vallecula is identified by an open arrow. The aryepiglottic folds course from the lateral edge of the epiglottis to the mucosa overlying the muscular processes of the arytenoid cartilages (left aryepiglottic fold identified by arrowheads; mucosa overlying left arytenoid cartilage identified by a). (B) Lateral view of the pharynx demonstrates the median glossoepiglottic fold (short arrow), tip of epiglottis (e), aryepiglottic folds (open arrow), and anterior walls of the piriform sinuses (long arrows).

Figure 6.3 Relationship of the laryngeal cartilages to the pharynx. (A) Line drawing in the frontal view demonstrates the tip of the epiglottic cartilage (e) above the level of the hyoid bone (b). The thyrohyoid membrane (M) connects the hyoid bone to the thyroid cartilage (t). The cricoid cartilage (c) is seen inferiorly. The white area represents the barium‐coated pharynx posterior to the larynx. (B) Frontal view of the pharynx shows a notch in the lateral hypopharyngeal wall (arrow in both A and B) where the thyrohyoid membrane joins the thyroid cartilage. Inferiorly, the hypopharynx is confined anteriorly by the thyroid cartilage.

Source: Reproduced from Rubesin et al. [2], with permission.

The piriform sinuses form the anterior portion of the lower hypopharynx. The piriform sinuses are pear‐shaped spaces created by protrusion of the larynx into the pharynx (Figure 6.4). These spaces are open posteriorly to the remainder of the hypopharynx. The aryepiglottic folds and mucosa overlying the muscular process of the arytenoid cartilages form the medial boundaries of the piriform sinuses.

The anterior wall of the pharyngoesophageal segment abuts the cricoid cartilage (Figure 6.5). The mucosa in this region is redundant, and there is abundant submucosal fat [2].