The esophagus is an organ in the digestive tract that connects the throat and stomach. In the human body, it is about 25 cm long and has the shape of an oblong tube. The main function of the esophagus is to transport swallowed food to the stomach. How is the esophagus structured? What are the most common diseases of the esophagus and how are they treated?

Human esophagusis a part of the digestive system - it measures about 25 cm and, depending on the segment, is located at the level of the neck, chest and abdomen. It begins at the level of the cervical spine (exactly the sixth cervical vertebra) and joins the stomach at the level of the tenth thoracic vertebra.

Esophagus: structure

The esophagus is made of three parts. The upper (cervical) part is the pharyngophageal sphincter muscle, the middle (thoracic) part is the body of the esophagus, and the lower (ventral) part is the lower esophageal sphincter

  • upper esophageal sphincter (UES) is the circular muscle that separates the throat from the esophagus
  • The lower esophageal sphincter (LES) is a circular smooth muscle that prevents stomach contents from flowing back into the esophagus. Physiologically, it is in a contractile state most of the time, it relaxes when swallowing food. The failure of the lower esophageal sphincter causes gastroesophageal reflux, i.e. the regurgitation of acid in the esophagus. On the other hand, in the case of increased resting tone of the lower esophageal sphincter and incomplete muscle relaxation during swallowing, esophageal achalasia develops. Food that does not pass into the stomach remains in the esophagus causing dilation. Treatment of esophageal achalasia involves injection of botulinum toxin into the sphincter as well as mechanical expansion of the lower esophageal sphincter. In addition, it is possible to perform an operation that involves cutting the muscles of the esophagus.

The wall of the esophagus consists of four parts (from the lumen of the esophagus):

  • of the mucosa, which has a folded structure and is covered with squamous multilayered non-keratinizing epithelium
  • submucosa
  • the muscle membrane, which on the outside is composed of longitudinal muscle fibers, and the inside ofcircular
  • outer membrane, made of loose connective tissue

The wall of the esophagus is made up of two types of muscles, both smooth and striated. The upper third of the esophagus is made up of striated muscles, while the remaining two thirds are made up of smooth muscles.

It is worth adding that the human esophagus has three physiological strictures.

The upper stenosis is at the point where the pharynx passes into the esophagus (the pharyngeal muscle, i.e. the upper esophageal sphincter), the middle stricture is formed at the level of the tracheal bifurcation (due to the compression of the left bronchus and the aorta descending the esophagus wall), and the lower stricture is where the esophagus passes into the stomach (lower esophageal sphincter).

Esophageal vascularization

The esophagus is supplied with arterial blood by the branches of the thoracic aorta, bronchial arteries and the esophageal branches of the left gastric artery.

Venous blood is drained by the veins that go to the azygus vein, the short airless vein, and the left gastric vein.

Lymphatic vessels enable the drainage of the lymph to the posterior mediastinal lymph nodes and the left gastric lymph nodes.

Esophageal innervation

The esophagus is an organ of the digestive system innervated by sympathetic nerves from the aortic plexus and upper cervical ganglion, as well as somatic vagus branches that supply the upper esophagus (striated muscle) and autonomic vagus nerves that supply the lower part esophagus (smooth muscle).

Esophagus Functions

The esophagus is an organ of the digestive system that connects the throat with the stomach, and its main function is to transport a swallowed bite of food to the stomach.

The following are involved in the swallowing process:

  • oral cavity
  • throat
  • esophagus

therefore there are 3 phases of swallowing:

  • oral
  • throat
  • esophagus

The esophageal phase is independent of the human will and is reflexive. After a bite of food, crushed in the mouth and mixed with saliva, reaches the throat, the pharyngophageal muscle, i.e. the upper esophageal sphincter, relaxes.

A bite of food enters the esophagus and travels down towards the stomach thanks to the perist altic wave. It is produced by alternating contractions of the circular muscle fibers that make up the inner layer of the esophageal wall.

In humans, the speed of a food bite is about 2-4 cm per second.It depends primarily on the type of food you swallow, its consistency and size, the contractile activity of the esophagus and the position of the body during eating and the weight of the swallowed food.

The force of esophageal contraction at the site of the wave is relatively small in the upper part of the esophagus, but gradually increases as the wave moves towards the stomach.

Solid food moves through the esophagus into the stomach much slower than liquid food, similar to food eaten horizontally.

Category:

Anatomy