Chapter 2, Page 3  

NORMAL ANATOMY, EMBRYOLOGY, AND HISTOLOGY OF THE ESOPHAGUS ANATOMY The esophagus connects the pharynx to the stomach; it courses through the posterior mediastinum and extends several centimeters beyond the diaphragm. Its length varies with the height of the individual and ranges from 25 to 30 cm. The distance of the esophagogastric junction from the teeth averages 40 cm, but ranges from as little as 30 to 43 cm (18). In children, the esophageal length also is related to height (26). In the resting state the esophagus is collapsed and measures about 3 cm in lateral diameter and 2 cm in anterior-posterior diameter. The esophagus begins at the level of the cricoid cartilage, at the apex of a funnel formed by the pharyngeal constrictors situated at the level of the sixth cervical vertebra (fig. 2-1). When viewed from above it appears as a transverse slit, with the pyriform sinus on either side. In its descent to the abdomen the esophagus follows the anteroposterior curvature of the vertebral column. It also has a reversed "S" configuration when viewed anteriorly. It exits the posterior mediastinum via the diaphragmatic hiatus through a tunnel approximately 5 centimeters in length. This diaphragmatic opening is relatively large and is located in the right crus of the diaphragm at the level of the seventh thoracic vertebra. It is filled with loose areolar tissue and contains the phrenoesophageal ligament which arises from the undersurface of the diaphragm and inserts into the esophagus about 3 cm above the hiatus. The ligament is thought to maintain a tight muscular seal between the diaphragm and the esophagus (6). The esophagogastric junction is defined as the point at which the tubular esophagus joins the saccular stomach. The squamocolumnar junction, also known as the z-line or ora serrata, consists of an irregular serrated margin, and does not necessarily coincide with the esophagogastric junction. In fact, the squamocolumnar junction may lie anywhere within the distal 2 cm of the tubular esophagus (14); endoscopically, this junctional zone sometimes extends several centimeters on either side of the lower sphincter (fig. 2-2). The International Union Against Cancer (UICC) has subdivided the esophagus into four regions: a cervical region and three intrathoracic and abdominal regions (see Table 2-1).