Esophagus: Imaging Approach and Differential Diagnosis

Esophageal Anatomy and Terminology

The esophagus is a fibromuscular tube ~ 25 cm long extending from the pharynx to the stomach. It begins at the upper esophageal sphincter, which is formed primarily by the cricopharyngeus muscle.

The lower esophageal sphincte r (LES) is also known as the phrenic ampulla or the esophageal vestibule and is further defined as the zone of higher resting tone or pressure. The LES is occasionally recognized radiographically as a 2-4 cm long luminal dilation between the esophageal "A" and "B" rings.

The "A" ring is a sporadically imaged indentation of the esophageal lumen at the cephalic end of the LES.

The " B " ring is a transverse mucosal fold that marks the gastroesophageal (GE) junction and often corresponds to the mucosal junction between the epithelium of the esophagus and that of the stomach. The endoscopist often recognizes a "Z" line at this junction with the esophageal mucosa appearing pearly pink in color and texture, while the gastric mucosa is more textured and deeper in color.

Pharynx

The pharynx is essential for effective speech, respiration, and swallowing. The nasopharynx extends from the skull base to the top of the soft palate and lies posterior to the nasal cavity. The oro (mesopharynx) lies between the soft palate and the hyoid bone. It lies posterior to the oral cavity. The hypo (laryngopharynx) extends from the hyoid to the cricopharyngeus muscle. It lies posterior and lateral to the larynx.