It is an organ that is part of the digestive system, it is characterized as a muscular cylindrical duct that carries food from the oropharynx to the stomach, this being its main function.
Transport food from the oral cavity to the stomach.
Anatomically adult esophagus is characterized by having a length between 25 to 30 cm
It has a cylinder shape and has three narrowings:
- Cricoid, corresponds to the cricopharyngeal muscle, with a light of 1.5 cm, is the narrowest region of the entire esophagus.
- Thoracic (Broncho-aortic), this is formed when the anterior and left lateral walls of the esophagus are pushed towards the esophagus’s light as they are crossed by the left main bronchus and the aortic arch. (Its diameter is around 1.6 cm).
- Frenic (Diaphragmatic), This is due to the mechanism of the gastroesophageal sphincter. (The diameter of this zone varies depending on the degree of distension of the esophagus to the passage of food, but values between 1.6 and 1.9 cm have been obtained)
And it is divided into 3 Regions or portions (Image 1)
- Cervical region: 5 cm long
- Thoracic region: 16-20 cm in length
- Abdominal region 3 cm long
- And the passage through the diaphragm the esophagus measures 1 cm
Its origin is located at the lower edge of the cricopharyngeus muscle (portion of the inferior constrictor muscle of the pharynx), located at the lower edge of the cricoid cartilage, at the level of C6 and C7. (Image 2)
Then the esophagus enters the thorax, locating anterior to the vertebral bodies and posterior to the trachea; at the level of T4 begins to locate posterior to the pericardium and anterior to the thoracic descending aorta, until reaching the diaphragm which crosses through the esophageal hiatus, this last portion (Abdominal portion) of the esophagus that faces to the left leading to the cardia of the stomach as seen in Image 1
It is the portion that lies between C6 and T2.
- On the anterior side, it is in contact with the trachea, which it passes slightly to the left from C7.
- On the posterior side we find the spinal column (prevertebral leaf of the cervical fascia)
- On the right lateral face, it is related to the right recurrent Laryngeal nerve, inferior thyroid vein and part of the right common carotid artery.
- On the lateral side Left: The left common carotid artery is closer to the esophageal border.
It is the portion that lies between T2 to the Diaphragm.
At its entrance to the thorax, the esophagus is always retrotracheal, passing between the two pre-domes.
- On the anterior side, above T4, the trachea is located and below it is the posterior face of the pericardium and the left atrium.
- On the posterior side, above T4, the spinal column and part of the thoracic duct are located and below the T4, the thoracic descending aorta is located.
- On the right lateral face, we find the azygos vein.
- On the left lateral aspect, it is related to the thoracic descending aorta in most of its course (Image 3).
It is the last portion of the esophagus that is just below the diaphragm before connecting with the stomach (Image 1), here it is mainly related in all its faces to the peritoneum.
In the cervical region the esophagus is irrigated mainly by the upper esophageal arteries that come from the inferior thyroid arteries; The thoracic region is the middle esophageal arteries that come directly from the aorta artery, the brochial and intercostal arteries; The abdominal region the lower esophageal arteries come from the posterior gastric and the lower phrenic arteries (Image 4).
The drainage, as well as the subjects previously seen in the esophagus, are classified according to their region. (Image 5)
- Cervical region, blood drains to the lower thyroid veins.
- Thoracic region, blood drains to the superior phrenic veins, bronchial, pericardial reaching the azygos vein which drains into the superior cava system.
- Abdominal region, the drainage is towards the left gastric vein through its gastroesophageal collaterals, tributary of the territory of the hepatic portal vein.
The esophagus has a motor innervation (Sympathetic – Parasympathetic). (Image 6)
- Sympathetic system adopts the pathway of the vascular nerves and reaches the esophagus with the arteries.
- The parasympathetic system reaches the esophagus by the left recurrent laryngeal nerve branch of the vagus nerve.
The esophagus as well as the entire digestive tract is made up of four histological layers (mucosa, submucosa, muscular and adventitia) (Image 7).
- The Mucous is the innermost layer of the esophagus and is made up of three parts
- Submucous: It is relatively lax with many elastic fibers, which allows considerable distension during the passage of the food bolus. You can also find small seromucous glands that allow lubrication of the mucosa.
- Muscular: It is made up of two layers.
- Adventicia: Conformed by loose connective tissue.
(1) Boya Vegue J. Atlas de Histología y Organografía Microscópica. 3a ed. Madrid, España: Editorial Medica Panamericana; 2011.
(2) Frank H. Netter M. Atlas de Anatomía Humana. 4.a ed. Barcelona, España: Elsevier Masson; 2007.
(3) Latarjet M, Ruiz Liard A. Esófago. 4a ed. Buenos Aires, Argentina: Editorial medica panamericana; 2007.