Function

The swallowing process The main task of the esophagus is to transport the ingested food into the stomach. In the mouth, humans can still control the swallowing process voluntarily, but from the throat onwards, the transport of food proceeds involuntarily (reflex-like) via a complicated sequence of centrally (brain-related) controlled muscle functions. The longitudinal muscle layer of the oesophagus creates a muscle wave that propels the food towards the stomach.

When the oesophagus is functioning properly, the muscles behind the chunks of food contract and push them forward. This type of propulsive movement, called peristalsis, is found throughout the gastrointestinal tract. During the swallowing process it is very important that the airways are reflexively closed so that no food components can be inhaled (aspirated).

Another very important task of the esophagus is to prevent acidic stomach contents from entering the esophagus (reflux). The last few centimeters of the esophagus are always closed at rest. This is particularly important because it is at this point that the acidic stomach contents are prevented from running back into the esophagus and damaging the mucous membrane of the esophagus (reflux esophagitis).

The following anatomical conditions play a role here:

The muscle loop of the diaphragm compresses the esophagus from outside (lower esophageal sphincter).
The esophagus is under continuous muscular longitudinal tension. Just before the opening of the stomach, the muscle layer is twisted particularly strongly around the longitudinal axis, so that a kind of muscular twist closure is created.
The pressure ratios between the thorax (negative pressure) and the abdomen (positive pressure) differ, with the positive pressure in the abdomen compressing the esophagus from the outside (compressed). This function is also called “functional cardiasphincter”.
A dense venous plexus in the Tela submucosa (see above) forms a kind of cushion, which narrows the passage, but at the same time remains soft so that food can pass through.
A minimal, short lasting reflux is normal (physiological).In the healthy esophagus, rapid self-cleaning is ensured by the constant peristalsis, which immediately transports the gastric acid back into the stomach so that it cannot cause any damage. In addition, swallowed saliva neutralizes the acid.

(tissue stained)

Tunica mucosa (mucous membrane)
Tela submucosa
Tunica muscularis