It is evident that if the abdomen is divided into quadrants, the left upper quadrant includes more than the upper gastrointestinal tract and spleen (such as the pancreas) and that the pylorus and duodenum pass out of this quadrant. Nevertheless, it is convenient to group these structures together. Perhaps because these are the structures palpated when this region of the abdomen is manually explored (see Chapter 36), along with the left lobe of the liver, these structures are commonly considered together by surgeons.

The region of the lower esophagus, including the esophageal hiatus, stomach, duodenum, vagus nerves, and spleen, is described in this section. First, the procedure of upper gastrointestinal endoscopy (Chapter 45) is described to present the general topography of the esophagus, stomach, and duodenum as well as a view from inside. Hiatal hernia repair (Chapters 46 and 47) introduces the anatomy in the region of the esophageal hiatus, the opening in the diaphragm through which the esophagus enters the abdomen. Chapter 48 describes laparoscopic esophagomyotomy, continuing the description of the distal esophagus. The discussion of this region is concluded in the chapter on vagotomies (Chapter 56).