Esophagus (Oesophagus) is a muscular tube of the gastrointestinal tract, the continuous passage through which food travels, connecting the pharynx, or throat, to the stomach. It begins in the neck, descends through the chest behind the trachea, or windpipe, and passes through the diaphragm to reach the upper abdomen.
Where is the esophagus located?
The esophagus begins at the lower border of the cricoid cartilage, the ring-shaped cartilage at the base of the larynx, or voice box. It continues from the pharynx and lies in front of the vertebral column. In the neck, the trachea lies directly in front of it.
In the chest, it passes through the mediastinum, the central compartment between the lungs. It descends behind the trachea and then behind the heart, particularly the left atrium, the chamber that receives blood returning from the lungs. The descending thoracic aorta, the main artery carrying blood down through the chest, lies mainly to its left before their relationship changes near the diaphragm.
The esophagus enters the abdomen through the esophageal hiatus, an opening in the diaphragm, the muscular partition between chest and abdomen. Its short abdominal course ends at the cardia, the region of the stomach surrounding its entrance.
What are the parts and normal narrowings of the esophagus?
The esophagus is divided according to the body region through which it passes. These divisions describe its course rather than separate organs.
| Part | Location | Main anatomical relationship |
|---|---|---|
| Cervical part | Neck | Behind the trachea and in front of the vertebral column |
| Thoracic part | Chest | Within the mediastinum, behind the trachea and heart |
| Abdominal part | Upper abdomen | Between the diaphragm and the stomach |
The passage narrows at its junction with the pharynx, where it is crossed by the aortic arch and left main bronchus, and where it traverses the diaphragm. The aortic arch is the curved portion of the aorta above the heart. The left main bronchus is the airway carrying air towards the left lung.
How is the esophagus wall organised?
The wall surrounds a lumen, the internal passage through which swallowed material travels. When empty, the lining forms longitudinal folds that can flatten as material passes.
From inside out, the wall has these layers:
- Mucosa: the inner lining, including stratified squamous epithelium, a protective covering made of multiple layers of cells with flattened surface cells.
- Submucosa: supporting connective tissue containing blood vessels, nerves and glands that produce lubricating mucus.
- Muscular layer: an inner circular layer and an outer longitudinal layer that narrow and shorten the tube during swallowing.
- Adventitia: an outer connective-tissue covering that joins most of the esophagus to surrounding structures.
The upper part contains skeletal muscle, the muscle type also used for body movement. The middle part contains a mixture of skeletal and smooth muscle, while the lower part contains smooth muscle, which contracts without conscious control. Part of the abdominal segment has a serosal covering, a thin, smooth outer membrane.
What does the esophagus do during swallowing?
Within the digestive system, the esophagus mainly transports swallowed food and liquid rather than digesting them. Peristalsis, a coordinated wave of muscular contraction, moves a bolus, or swallowed mass, towards the stomach. Mucus reduces friction along the lining.
At its upper end, the upper esophageal sphincter is a muscular closure formed mainly by the cricopharyngeal part of the inferior pharyngeal constrictor, a muscle of the lower throat. It relaxes during swallowing to admit the bolus.
At the lower end, the lower esophageal sphincter is a functional zone of increased muscular tone rather than a clearly separate anatomical ring. Together with the surrounding diaphragm, it helps limit backward movement of stomach contents.
What supplies and drains blood from the esophagus?
Its blood supply comes from different arteries along its course. The cervical part receives branches of the inferior thyroid arteries. Thoracic supply includes branches from the thoracic aorta, represented by an esophageal artery, and contributions from bronchial arteries; the abdominal part receives branches of the left gastric and left inferior phrenic arteries.
The esophageal veins drain towards the inferior thyroid veins in the neck and the azygos venous system in the chest. Near the stomach, they communicate with the left gastric vein, which drains into the portal system carrying blood towards the liver.
How is the esophagus innervated?
Its nerve supply includes the autonomic nervous system, which regulates involuntary activity. Vagus nerves provide motor supply to the upper skeletal muscle and parasympathetic input, the autonomic input supporting digestive activity, to the lower smooth muscle.
Vagal and sympathetic fibres form the esophageal plexus, an interconnected network of nerves around the thoracic esophagus. Sympathetic fibres come from the sympathetic trunks, nerve chains alongside the vertebral column. Local nerve networks within the wall help coordinate muscular movement and glandular secretion.
Where does lymph from the esophagus drain?
Lymph, fluid collected from tissues by the lymphatic system, drains through channels in the esophageal wall to regional lymph nodes. These are small organs that filter lymph.
The cervical part drains towards deep cervical nodes in the neck. Thoracic drainage reaches mediastinal nodes, while abdominal drainage reaches left gastric and coeliac nodes near the upper abdominal arteries. Longitudinal lymph channels connect regions along the wall, so drainage is not confined to sharply separated segments.
How can you find the esophagus in the 3D model?
In the 3D model beside this article, rotate the view and zoom to adjust your viewpoint. Select a structure and isolate it, then hide or fade other structures to adjust their visibility. Switch layers to change the view, or pull parts apart. You can also cut a section along the sagittal, coronal or transverse plane, then rotate or zoom to adjust the section view.