Figure 1 - Anatomy of the diaphragmatic hiatus.

In the most common anatomy, the muscular elements of the crural diaphragm derive from the right diaphragmatic crus. The right crus arises from the anterior longitudinal ligament overlying the lumbar vertebrae. Once muscular elements emerge from the tendon, two flat muscular bands form, which cross each other in scissor-like fashion, form the walls of the hiatus, and decussate with each other anterior to the esophagus. (Source: Modified from Marchand ⁵ with permission from Society of Thoracic Surgeons.)