Location and formation
Esophageal hiatus (hiatus oesophageus) is one of the three main openings of the unpaired dome-shaped muscle known as the diaphragm. It projects at the level of the tenth thoracic vertebra (Th10).
Anatomically, the opening is located in the lumbar part of the diaphragm (pars lumbalis). This part consists of the right and left crura (crus dextrum et sinistrum), which originate from the anterior surface of the bodies of the upper lumbar vertebrae and intervertebral discs. The esophageal hiatus itself is formed by the muscular bundles of the right crus of the diaphragm.
What passes through the esophageal hiatus?
The primary role of this opening is to provide communication between the thoracic and abdominal cavities. Passing through the hiatus oesophageus are:
- Esophagus (oesophagus) — at this level, its thoracic part (pars thoracica) ends and its short abdominal part (pars abdominalis) begins, measuring 1–3 cm in length before transitioning into the stomach. One of the three physiological constrictions of the esophagus, the diaphragmatic constriction, is located in the area of the hiatus.
- Vagal trunks (trunci vagales) — the anterior and posterior trunks of the vagus nerve (n. vagus). The right trunk runs along the posterior wall of the esophagus, while the left trunk lies against its anterior wall.
- Blood vessels — branches of the left gastric artery (a. gastrica sinistra) and accompanying veins.
- Lymphatic vessels.
Function and mechanism of action
Unlike the caval opening, the margins of which are formed by fibrous tissue of the central tendon and do not compress, the esophageal hiatus has muscular margins.
During inspiration, the muscular bundles of the diaphragmatic crura contract. This leads to the narrowing of the esophageal hiatus, allowing it to perform a sphincteric function. Contraction of the crura closes the intra-diaphragmatic segment of the esophagus.
To ensure the reliability of this mechanism, the esophagus is firmly anchored within the hiatus: the adventitia of the esophagus blends with the muscles of the diaphragm, forming a connecting fibrous-tissue layer.
Topography and adjacent structures
The esophageal hiatus is located between the other two major passages of the diaphragm:
- Superiorly, at the level of Th8, in the translucent plate of the central tendon lies the vena cava opening (foramen venae cavae).
- Inferiorly, at the level of Th12, posterior to the diaphragm lies the aortic hiatus (hiatus aorticus), formed by the tendinous median arcuate ligament.
The abdominal surface of the diaphragm at the site of esophageal contact is an exception to the general rule: this area (like the bare area of the liver, and the contact areas of the kidneys and adrenal glands) is not covered by peritoneum, whereas the rest of the abdominal surface is lined by it via the subperitoneal fascia.
Class and exam questions
At the level of which vertebra is the esophageal hiatus of the diaphragm located?
It projects at the level of the tenth thoracic vertebra (Th10).
Which nerves pass through the hiatus oesophageus along with the esophagus?
The anterior and posterior vagal trunks (branches of the 10th cranial nerve — the vagus nerve) pass through it. The left trunk runs along the anterior wall of the esophagus, and the right trunk along the posterior wall.
Does the lumen of the esophageal hiatus change during respiration?
Yes. Since the opening is formed by the muscular bundles of the right crus of the diaphragm, they contract during inspiration. This closes the intra-diaphragmatic segment of the esophagus, providing a sphincteric function.
What else to study on this topic
- Lumbar part of the diaphragm and its crura
- Abdominal part of the esophagus
- Vagus nerve (n. vagus)
- Aortic hiatus of the diaphragm
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