Cardias

The cardia is the anatomical region of junction between the esophagus and the stomach, normally located in the abdomen 2 to 4 cm below the diaphragm. Anatomically, the cardia is now considered part of the stomach.

Immediately upstream of the cardia, the circular muscle fibers of the esophagus acquire sphincter action, in the sense that in conditions of rest they remain contracted, while they relax during belching, the descent of food into the stomach and its ascent during vomiting; in the other phases of the digestive processes, however, this functional sphincter remains closed and contracted, to prevent the acid content of the stomach from rising up into the esophagus, irritating its internal walls. The sphincter we are talking about is known as cardial sphincter, gastroesophageal sphincter, lower esophageal sphincter (LES) or cardial valve. We speak of functional sphincter because there is no specific anatomically demonstrable muscle bundle, but only an area of ​​the esophageal musculature, vertically extended for a couple of centimeters, which contracts, preventing the flow of fluids along the esophagus.

In the cardia we witness the transition between the esophageal and gastric mucosa; at the point of passage, a frayed line (line Z) separates the gastric mucosa, which is redder and more wrinkled, from the esophageal mucosa (at the level of the cardia occurs the passage between two specialized epithelia: the monostratified cylindrical epithelium of the gastric mucosa from one side and the multi-layered pavement epithelium of the esophageal one on the other).

The cardia is innervated by the vagus nerve, which has an inhibiting function, and by afferents of the sympathetic nervous system, which instead have an exciting function. Its biological function is facilitated by the angle of His, the subdiaphragmatic tract of the esophagus, the diaphragmatic crura and the brake-esophageal ligament.

Sometimes the lower esophageal sphincter, or other components of this "backflow barrier", may not function perfectly or not function at all. In these cases, we speak of gastroesophageal reflux disease (GER), a complex of clinical situations that extends from simple symptomatic reflux to simple or complicated mucosal damage (esophagitis, Barrett's esophagus). The characteristic symptoms of these conditions include heartburn and acid regurgitation, retrosternal pain (similar to anginal pain), nausea, vomiting, hiccups, difficulty or pain in swallowing, sometimes respiratory disorders, jet sialorrhea and hemorrhages (shown by coloring blackish in the stool or with traces of blood in the vomit).

Carcinoma of the cardia is today a growing neoplasm in Western countries; there are numerous possible risk factors, such as alcohol, tobacco and obesity, but the only significantly correlated factor seems to be Barrett's esophagus, a pre-neoplastic condition secondary to chronic gastroesophageal reflux (malignant cardia cancer is therefore more frequent in men compared to women, and in the age groups over 50 years).