Phrenoesophageal ligament

UPDATED: The [phrenoesophageal ligament] or phrenoesophageal membrane is part of a complex system that closes off the esophageal hiatus, one of the seven hiatuses in the respiratory diaphragm, preventing the herniation of abdominal structures into the thoracic mediastinum.

The connective tissue layer called the endoabdominopelvic fascia, which lines the inner aspect of the abdominopelvic cavity, is found as a "glue" between the respiratory diaphragm and the parietal peritoneum. At this point the endoabdominopelvic fascia is called the "infradiaphragmatic fascia".

When the infradiaphragmatic fasia gets to the edge of the esophageal hiatus, it splits into ascending and a descending components or limbs. These are the superior and inferior phrenoesophageal ligaments or phrenoesophageal membranes. These phrenoesophageal ligaments create a circular disc-like plug between the abdomen and the thorax. This "plug" is reinforced by a infradiaphragmatic fat pad found internal to the phrenoesophageal ligament.

The phrenoesophageal ligaments are reinforced externally. On their thoracic aspect by the endothoracic fascia, and on the abdominal side, by parietal peritoneum.

Esophageal hiatus
Images property of:CAA.Inc. Artist:Dr. E. Miranda
The ascending limb fuses superiorly with the esophageal fascia, which lines the external aspect of the longitudinal muscle of the esophagus, as the thoracic esophagus does not have a serosa layer. The descending limb fuses inferiorly with the esophageal fascial covering of the longitudinal ligament as it is covered by the peritoneum . Failure of the phrenoesophageal ligaments can predispose to esophageal hiatus hernia.
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