General anatomy and topography
The esophagus begins in the neck, just below the cricopharyngeus muscle (m. cricopharyngeus), which corresponds to the level of the sixth cervical vertebra (C6). It descends into the abdominal cavity, passing through the posterior mediastinum.
Three parts of the esophagus are distinguished:
- Cervical part (short) — lies posterior to the trachea.
- Thoracic part (long) — passes posterior to the aortic arch, left atrium, and left main bronchus. These structures create physiological impressions on its wall.
- Abdominal part (short) — begins after passing through the esophageal hiatus of the diaphragm (hiatus oesophageus) at the T10 level, runs posterior to the left lobe of the liver, and empties into the stomach at the T11 level.
The esophageal wall consists of five layers: the mucosa, muscularis mucosae, submucosa, muscularis propria, and the outer layer (adventitia, or serosa in the lower part). The mucosa is lined with non-keratinized stratified squamous epithelium. The site of its transition into the gastric columnar epithelium is called the gastroesophageal junction, or Z-line (Z-line).
Anatomic segments and their features
The esophagus can be divided into three equal segments (8 cm each), which differ in muscle structure, innervation, and blood supply.
| Compartment | Musculature | Arteries | Veins | Lymphatic drainage |
|---|---|---|---|---|
| Cervical and upper thoracic | Striated muscle | Inferior thyroid | Inferior thyroid | Lower deep cervical nodes |
| Mid-thoracic | Mixed | Branches of the aorta | Azygos venous system | Mediastinal nodes |
| Lower thoracic and abdominal | Smooth | Left gastric | Left gastric | Left gastric nodes |
During development, the stratified squamous epithelium of the esophagus forms from the foregut endoderm. The striated muscles originate from the 4th and 6th pharyngeal arches, smooth muscles from the somite mesenchyme, and the nerve plexuses from neural crest cells.
Motility physiology and sphincters
At rest, the esophagus is relaxed. To prevent reflux and control the passage of food, high-pressure zones — sphincters — exist.
- Upper esophageal sphincter (UES) is formed by the cricopharyngeus muscle and the upper part of the cervical esophagus.
- Lower esophageal sphincter (LES) is a zone about 3 cm long in the region of the gastroesophageal junction. It is formed by the lower muscle fibers of the esophagus and the diaphragmatic hiatus.
Food propulsion is provided by peristalsis. Primary peristalsis is triggered by the swallowing reflex. If the food bolus is delayed, secondary peristalsis occurs. Non-propulsive spastic movements—tertiary contractions—are also possible, which often indicate motility disorders.
Constrictions and imaging methods
There are several physiological constrictions along the esophagus where foreign bodies most frequently get stuck: in the area of the cricopharyngeus muscle, aortic arch, left main bronchus, and the esophageal hiatus of the diaphragm.
Various imaging methods are used to diagnose pathologies:
- Endoscopy is the method of choice.
- Fluoroscopy is most commonly performed with a barium suspension. Double contrast (with gas) clearly outlines the mucosal relief.
- Water-soluble contrast is used strictly when perforation is suspected. It is essential to use only low-osmolarity agents to avoid pulmonary edema in case of accidental aspiration.
- CT and PET-CT are used for tumor staging and in trauma cases.
Briefly: answers to topical questions
How is the portosystemic anastomosis formed in the venous plexus of the esophagus?
The esophageal portosystemic anastomosis is formed in the region of the cardiac part of the stomach and the lower third of the esophagus. It connects the portal venous system and the superior vena cava (SVC) system.
- Portal system — outflow occurs via the left gastric vein (v. gastrica sinistra) into the portal vein (v. portae).
- SVC system — blood drains via the esophageal venous plexus (plexus venosus oesophageus) into the azygos vein (v. azygos), and then into the SVC.
In portal hypertension, the functioning of this anastomosis leads to esophageal varices and creates a risk of hemorrhage.
Which nerves provide parasympathetic and sympathetic innervation to the esophagus?
Innervation of the esophagus is provided by branches of the vagus nerves and the sympathetic trunk, which together form the esophageal plexus (plexus oesophageus).
- Parasympathetic innervation is provided by branches of the vagus nerve (n. vagus). The anterior trunk (truncus vagalis anterior), derived from the left vagus nerve, lies on the anterior surface of the organ, while the posterior trunk (truncus vagalis posterior), derived from the right vagus nerve, lies on the posterior surface.
- Sympathetic innervation is supplied by sympathetic fibers originating from the thoracic ganglia of the sympathetic trunk.
These nerves form intramural plexuses that coordinate peristaltic contractions.
What are the characteristic radiological signs of achalasia of the cardia on a barium swallow study?
On a barium swallow study, achalasia of the cardia is characterized by the following features:
- Shape of constriction — symmetrical narrowing of the distal segment resembling a "bird's beak" or "rat tail" with smooth walls.
- Lumen changes — suprastenotic dilation of the esophagus.
- Motility — absence of thoracic esophageal peristalsis and spastic wall contractions.
- Evacuation — delayed contrast evacuation and failure of the cardia to open.
- Stomach — absence of the gastric gas bubble.
To remember the physiological constrictions of the esophagus from top to bottom, use the mnemonic: Cricoid, Aorta, Bronchus, Diaphragm (Cricopharyngeus muscle, aortic Arch, left main Bronchus, esophageal hiatus of the Diaphragm).
Class and exam questions
Where is the Z-line located and what does it look like?
The Z-line is located in the zone of the gastroesophageal junction (approximately 40 mm from the incisors). It appears as a sharp boundary between the pale pink squamous epithelium of the esophagus and the darker columnar epithelium of the stomach.
What contrast agent should be used if esophageal rupture is suspected?
When perforation or anastomotic leakage is suspected, it is necessary to use a low-osmolarity water-soluble contrast agent (e.g., iopamidol). Barium must not be used.
What are tertiary esophageal contractions?
These are non-propulsive (spastic) wall contractions that do not participate in food propulsion. They are frequently observed in various motility disorders.
What else to study on this topic
- Radiographic appearance of the esophagus in normal condition and with tertiary contractions
- Features of blood supply and venous drainage in the lower segment (risk of varices)
- Embryological origin of the layers of the esophageal wall
- Double-contrast technique in fluoroscopy
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