Stomach

In human biology, the stomach is a remarkable organ with important digestive, nutri­tional, and endocrine functions. Its biological function is to store and facilitate the diges­tion and absorption of ingested food and helps regulate appetite. Treatable diseases of the stomach are common and the stomach is accessible and relatively forgiving; thus it is a favorite therapeutic target. In order to provide intelligent diagnosis and treatment, the physician and surgeon must understand human biology, gastric anatomy, physiol­ogy, and pathophysiology. This includes a sound understanding of the mechanical, secretory, and endocrine processes through which the stomach accomplishes its important biological functions. It also includes a familiarity with the common benign and malignant gastric disorders of clinical significance, especially peptic ulcer and gastric cancer.

ANATOMY

Embryology

The stomach arises as a dilatation in the tubular embryonic foregut during the fifth week of gestation. It assumes its nor­mal asymmetric shape and position by the end of the seventh week through descent, rotation, and progressive dilation, with dispropor­tionate elongation of the greater curvature. It is likely that there is a congenital predisposition to some unusual benign gastric problems such as diverticulum or massive hiatal hernia with abnormal gastric rotation and fixation.

Gross Anatomy

Anatomic Relationships and Gross Morphology

The stomach is recognized in human biology as the asymmetrical, pear-shaped, most proximal abdominal organ of the digestive tract. The part of the stomach attached to the esophagus is called the cardia. Just proximal to the cardia at the gastroeso­phageal (GE) junction is the anatomically indistinct but physiologically demonstrable lower esophageal sphincter. At the distal end, the pyloric sphincter connects the stomach to the proximal duode­num. The stomach is relatively fixed at these points, but the large midportion is quite mobile.

The superior-most part of the stomach is the distensible floppy fundus, bounded superiorly by the diaphragm and laterally by the Teen. The angle of His is where the fundus meets the left side of the GE junction. Generally, the inferior extent of the fundus is considered to be the horizontal plane of the GE junction, where the body or corpus of the stomach begins. The body of the stomach contains most of the parietal cells, some of which are also present in the cardia and fundus. The body is bounded on the right by the relatively straight lesser curvature and on the left by the more curved greater curvature. At the angularis incisura, the lesser curvature turns rather abruptly to the right, marking the anatomic beginning of the antrum, which comprises the distal 25 to 30% of the stomach.

The organs that commonly surround the stomach are the liver, colon, spleen, pancreas, and occasionally the kidney. The left lateral segment of the liver usually covers a large part of the anterior stomach. Inferiorly, the stomach is attached to the transverse colon by the gastrocolic omentum. The lesser curvature is tethered to the liver by the hepatogastric ligament also referred to as the lesser omentum. Posterior to the stomach is the lesser omental bursa and the pancreas.