Esophageal Constrictions

The esophagus has several natural constrictions along its course, which are clinically significant as they are common sites for the impaction of swallowed foreign objects, lodging of corrosive substances, or obstruction by strictures and malignancies. These constrictions are created by external compressions or intrinsic anatomical features. There are typically four main esophageal constrictions observed during endoscopy and imaging studies.

List of Constrictions

• 1. Upper (Cervical) Constriction: At the level of the pharyngoesophageal junction (C6 vertebra)
• 2. Thoracic (Aortic Arch) Constriction: Where the arch of the aorta crosses the esophagus (T4 vertebra)
• 3. Bronchial Constriction: Where the left main bronchus crosses the esophagus (T5–T6)
• 4. Lower (Diaphragmatic) Constriction: Where the esophagus passes through the esophageal hiatus of the diaphragm (T10)

1. Upper (Cervical) Constriction

Location

Located at the junction of the pharynx and esophagus, opposite the C6 vertebral level.

Cause

Formed by the cricopharyngeus muscle, part of the inferior pharyngeal constrictor. This is the narrowest part of the esophagus.

Clinical Significance

• Common site of impaction for bones and large tablets
• Area prone to the development of Zenker's diverticulum just above this zone

2. Thoracic (Aortic Arch) Constriction

Location

Opposite the T4 vertebral level, where the arch of the aorta indents the anterior wall of the esophagus.

Cause

External compression by the arch of the aorta as it loops over the left main bronchus and crosses the esophagus.

Clinical Significance

• Visible on contrast radiographs as a smooth indentation
• Potential site for esophageal stasis in dysmotility disorders

3. Bronchial Constriction

Location

Occurs at the level of the T5–T6 vertebrae, where the left main bronchus crosses anterior to the esophagus.

Cause

External impression by the bronchus and adjacent structures, especially when enlarged (e.g., in bronchogenic carcinoma or lymphadenopathy).

Clinical Significance

• Another common site for foreign body impaction
• Can be exaggerated in pathologies such as bronchial tumors or left atrial enlargement

4. Lower (Diaphragmatic) Constriction

Location

Occurs at the level of the T10 vertebra, where the esophagus passes through the esophageal hiatus of the diaphragm.

Cause

Constriction by the right crus of the diaphragm forming a muscular sphincter-like mechanism at the gastroesophageal junction.

Clinical Significance

• Important in preventing gastroesophageal reflux
• Implicated in conditions like hiatal hernia and GERD

Distance from Incisor Teeth (Approximate)

These constrictions can also be described by their distance from the upper incisor teeth during endoscopy:

• Upper constriction (C6): ~15 cm
• Aortic arch (T4): ~22.5 cm
• Left bronchus (T5–T6): ~27.5 cm
• Diaphragmatic (T10): ~40 cm

Radiological and Endoscopic Relevance

• Barium swallow: Constrictions appear as consistent narrowings at predictable levels
• Endoscopy: Clinicians must navigate constrictions with care, especially when inserting instruments or removing foreign bodies

Topographic Summary

• Total constrictions: Four
• Locations: C6, T4, T5–T6, T10
• Causes: Cricopharyngeus muscle, aortic arch, left bronchus, diaphragm
• Clinical importance: Sites of impaction, reflux barrier, visible landmarks in radiology