The seven hiatuses (openings) of the respiratory diaphragm

Respiratory diaphragm. Public domain
Respiratory diaphragm

The term [hiatus] derives from the Latin word [hiare], meaning to "gape" or to "yawn". In human anatomy this term is used to mean an "opening" or a "defect". It must be pointed out that in anatomy (and surgery) the term "defect" does not necessarily mean "defective". In most cases a "defect" is a normal opening in a structure, such as the esophageal hiatus. The plural form is either [hiatus] or [hiatuses].

In the case of the respiratory diaphragm, there are seven such openings, seven normal hiatuses. On top of this, you can find an abnormal opening caused by incomplete congenital closure of the dome of the diaphragm, a congenital diaphragmatic hernia (CDH), also known as Bochdalek's hernia, found in the posterior aspect of the respiratory diaphragm.

The seven hiatuses of the respiratory diaphragm are:

• Esophageal hiatus

• Aortic hiatus

• Inferior vena cava hiatus

• Hiatuses (2) for the superior epigastric vessels, which are the inferior continuation of the internal thoracic (mammary) vessels. Also known as the hiatuses of Morgagni. A hernia in a newborn through this hiatus is also considered a CDH.

• Hiatuses (2) for the splanchnic nerves

Based on the above it is wrong (maybe not wrong, but incomplete) to say that a patient has a "hiatal hernia", as the term does not include which hiatus is involved. In fact the hernia of Morgagni is also a "hiatal hernia" as the hernia passes through a normal defect in the respiratory diaphragm. Come to think of it, it could also be a hernia in a hiatus somewhere else in the body, such as a hernia of Schwalbe, a type or pelvic diaphragm hernia.

Note: Thanks to DHREAMS of the Columbia University Medical Center for the link on CDH.

Sources:
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. "Medical Meanings - A Glossary of Word Origins" Haubrich, WD. ACP Philadelphia
3 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
4. "Anatomy of the Human Body" Henry Gray 1918. Philadelphia: Lea & Febiger Image modified by CAA, Inc. Original image by Henry Vandyke Carter, MD., courtesy of bartleby.com