Esophagus: anatomy, functions, common diseases

The esophagus is a hollow, muscular organ that transports food and liquid from the pharynx to the stomach. Its function appears simple, but in reality, it requires precise muscle coordination, neural regulation, and barriers that prevent the reflux of stomach contents. [1]

The esophagus's primary function is transport: peristalsis moves food downward, and sphincter zones at the top and bottom open and close at the right moment. Disruption of any part of this chain can lead to dysphagia, pain when swallowing, regurgitation, and a sensation of a "lump" in the chest. [2]

The esophagus does not "digest" food and plays almost no role in nutrient absorption. Its purpose is to safely and quickly transport contents, minimizing mucosal trauma and preventing aspiration into the airways during swallowing. [3]

Some esophageal diseases develop due to chronic exposure to acid and bile reflux, while others are due to immune mechanisms, infections, drug-induced damage, or complications of portal hypertension. Therefore, "esophagus pain" is not a single diagnosis, but requires different tests depending on the underlying symptom. [4]

Table 1. The main functions of the esophagus and what breaks down when it is disrupted

Function	How is it ensured?	Typical symptoms of a failure
Conducting food	peristalsis, coordinated work of muscle layers	dysphagia, food "sticking"
Reflux barrier	lower esophageal sphincter, crura of the diaphragm, acid clearance	heartburn, regurgitation, esophagitis
Protecting the airway when swallowing	coordination of the swallowing act, upper esophageal sphincter	choking, coughing when swallowing
Self-cleaning	saliva, peristalsis, acid neutralization	chronic irritation of the mucous membrane

Source on physiology and basic mechanisms. [5]

Anatomy of the esophagus: sections, constrictions, blood supply, innervation

In adults, the esophagus is typically approximately 25-27 cm long, passing through the neck, chest, and a short abdominal segment before entering the stomach. An important practical detail: anatomical landmarks are needed for interpreting endoscopy, contrast radiography, and for understanding where foreign bodies most often become lodged.

The esophagus is conventionally divided into the cervical, thoracic, and abdominal sections. In the thoracic section, the esophagus is closely connected to the trachea, aortic arch, left main bronchus, and pericardium, which explains why some tumors or inflammatory processes can cause atypical chest pain and complications if diagnosed late.

Physiological stenosis corresponds to areas of increased risk of injury: the upper sphincter region, the intersection with large structures in the chest, and the passage through the esophageal hiatus of the diaphragm. These areas are important in dysphagia and in interpreting strictures, rings, and cicatricial changes.

The esophagus has a segmental blood supply, with a rich network of anastomoses; innervation includes parasympathetic influences from the vagus nerve and sympathetic pathways. This explains why motor and sensory disturbances can manifest as chest pain mimicking cardiac symptoms, and why motility assessment requires specialized methods. [9]

Table 2. Anatomical sections and clinical significance

Department	Approximate length	Key landmarks	Why is it important?
Cervical	5-7 cm	behind the trachea	risk of damage from foreign bodies and manipulations
Chest	16-18 cm	near the aortic arch and left bronchus	zones of physiological constriction and compression
Abdominal	1.5-4 cm	below the diaphragm before entering the stomach	reflux zone and hernia of the esophageal opening of the diaphragm

Landmarks and anatomical connections.

Esophageal wall and protective barriers

The esophageal wall consists of the mucosa, submucosa, muscularis propria, and extensor esophagus. The mucosa protects the tissue from mechanical trauma and contact with food, while the submucosa contains vessels, nerves, and glands that contribute to local defense.

The muscularis propria is structured such that the upper third contains more striated fibers, while smooth muscle gradually predominates lower down. This has clinical significance: different sections of the esophagus respond differently to neurological disorders and certain types of motor disorders.

The reflux barrier is not created by a single "valve" structure, but by a complex of factors: the tone of the lower esophageal sphincter, support from the crura of the diaphragm, the angle of entry of the esophagus into the stomach, the effectiveness of peristaltic clearance, and acid neutralization by saliva. Therefore, reflux can be pronounced even without severe anatomical defects, and vice versa. [13]

Long-term acid exposure leads to mucosal inflammation, which can lead to erosions and scarring. In some patients, chronic reflux leads to metaplasia, known as Barrett's esophagus, which increases the risk of esophageal adenocarcinoma and requires monitoring according to gastroenterological society standards. [14]

Table 3. Wall layers and their clinical “role”

Layer	Main function	What happens when there is damage?
Mucous	barrier and protection	esophagitis, erosions, ulcers
Submucosa	vessels, nerve plexuses, glands	swelling, bleeding, pain
Muscular membrane	peristalsis and tone	dysphagia, motor disorders
Outer shell	fixation and protection	risk of spread of inflammation into the mediastinum during perforation

Generalization of structure and functions. [15]

Motility: How the esophagus moves food and why spasms occur

Swallowing initiates a complex sequence of events: opening of the upper esophageal sphincter, passage of the bolus, and then a wave of peristalsis that propels the contents downward. The quality of this process depends on the coordinated work of nerve centers and local nerve plexuses. [16]

Motility disorders are diagnosed using high-resolution manometry, and the current classification of such disorders is described in the Chicago Classification version 4.0. This system emphasizes the need for a standardized protocol and confirmation of the diagnosis with provocative tests, since some "anomalies" without clinical manifestations have no independent significance. [17]

Achalasia is a key diagnosis in which the lower esophageal sphincter relaxes insufficiently and peristalsis is impaired. The American College of Gastroenterology guidelines detail diagnostic features and compare treatment options, including pneumatic dilation, peroral endoscopic myotomy, and surgical myotomy. [18]

Other motor disorders, including hypomotility and spastic variants, can cause chest pain and dysphagia, sometimes mimicking coronary artery disease. In such cases, it is important not to rely solely on a "heartburn pill," but to confirm or exclude a motor diagnosis with specialized testing. [19]

Table 4. Frequent motor disorders and their typical manifestations

State	Key mechanism	Typical complaints	The main method of confirmation
Achalasia	insufficient relaxation of the lower sphincter, loss of peristalsis	progressive dysphagia, regurgitation, weight loss	high-resolution manometry, radiography with contrast
Spastic disorders	uncoordinated abbreviations	attacks of chest pain, episodic dysphagia	high-resolution manometry according to Chicago Classification 4.0
Hypomotility	weak contractions	solid food getting stuck, reflux	high-resolution manometry

Source for classification and achalasia. [20]

Common diseases of the esophagus and modern therapy

The most common problem is gastroesophageal reflux disease, in which reflux causes symptoms or complications. Current guidelines allow for clinical diagnosis based on typical symptoms, but in cases of alarming signs and treatment ineffectiveness, instrumental diagnostics are recommended. [21]

Treatment for gastroesophageal reflux disease typically begins with proton pump inhibitors and lifestyle changes. The American College of Gastroenterology guidelines specifically discuss treatment duration, indications for maintenance therapy, and referral criteria for antireflux surgery and endoscopic interventions. [22]

Barrett's esophagus is a complication of chronic reflux in which normal squamous epithelium is replaced by specialized intestinal metaplasia. The American College of Gastroenterology guidelines and European recommendations describe approaches to confirming the diagnosis, monitoring intervals, and endoscopic eradication therapy for dysplasia. [23]

Esophageal strictures often develop after prolonged inflammation, chemical burns, or radiation therapy. Modern reviews describe the classification of strictures into simple and complex and list endoscopic treatment methods: dilation, local steroid injections, stenting, and scar dissection for refractory cases. [24]

Table 5. Reflux, esophagitis, Barrett's esophagus: guidelines for management

State	What confirms the diagnosis?	Basic therapy	When advanced tactics are required
Gastroesophageal reflux disease	symptoms, endoscopy if indicated, functional tests if in doubt	proton pump inhibitor, lifestyle modification	relapses, complications, need for long-term therapy
Erosive esophagitis	endoscopy	proton pump inhibitor, then support as indicated	bleeding, strictures, relapses
Barrett's esophagus	endoscopy with biopsies according to protocol	reflux control	dysplasia, need for endoscopic ablation

Guidelines for Gastroesophageal Reflux Disease and Barrett's Esophagus.[25]

Diagnosis, prevention, and red flags

Upper gastrointestinal endoscopy remains a key method for assessing the esophageal mucosa: it identifies esophagitis, strictures, suspicious lesions, reflux complications, and allows for biopsy. Quality endoscopy and standardized reporting are important for the early detection of dysplasia and tumors. [26]

Functional methods are used when endoscopy is inconclusive. 24-hour acid or impedance recording and high-resolution manometry help confirm reflux, differentiate it from functional disorders, and diagnose motor disorders according to Chicago Classification 4.0. [27]

A special group of patients are those with cirrhosis and portal hypertension, who develop esophageal varices and are at risk of bleeding. The Baveno VII consensus describes current risk stratification, indications for screening, and prevention of first bleeding. [28]

Oncologic suspicion is important in cases of progressive dysphagia, unexplained weight loss, iron deficiency anemia, bleeding, and long-standing heartburn with risk factors. National Cancer Institute sources and treatment guidelines confirm that management depends on the stage and may include endoscopic methods, surgery, chemotherapy, radiation therapy, and immunotherapy. [29]

Table 6. Which studies are chosen for different complaints

Complaint or situation	First steps	When special tests are needed
Typical heartburn without warning signs	proton pump inhibitor trial therapy, response assessment	if there is no effect, if atypical reflux is suspected
Dysphagia, odynophagia	endoscopy as a priority	manometry if a motor disorder is suspected
Chest pain with cardiology ruled out	assessment of reflux and motility	high-resolution manometry, functional tests
Suspected Barrett's esophagus	endoscopy with biopsies	observation and ablation as indicated
Risk of variceal bleeding	risk stratification for cirrhosis	endoscopy and prophylaxis according to Baveno VII

Sources for gastroesophageal reflux disease, motility, and portal hypertension. [30]

Table 7. Red flags: when urgent assessment is required

Sign	Why is it dangerous?	Typical action
Rapidly progressive dysphagia	risk of tumor or severe stricture	urgent endoscopy
Vomiting blood or black stools	possible bleeding	urgent Care
Unexplained weight loss	risk of cancer	accelerated diagnostics
Severe pain after swallowing chemicals	risk of burns and perforation	urgent specialized care
Dysphagia with aspiration and choking	risk of food getting into the respiratory tract	urgent assessment of swallowing and airway

Oncological and clinical landmarks. [31]