|The diaphragm. Under surface. (Aortic hiatus labeled near center.)|
|Celiac and cranial mesenteric ganglion in a cat. 1 Crus sinistrum (Diaphragma), 2 hiatus aorticus, 3 Aorta, 4 Arteria lumbalis, 5 Nervus splanchnicus major, 6 Arteria celiaca, 7 Arteria phrenica caudalis, 8 Ganglion celiacum, 9 Plexus celiacus, 10 Ganglion mesentericum craniale, 11 Plexus mesentericus cranialis, 12 Arteria mesenterica cranialis, 13 Nervus splanchnicus minor, 14 Adrenal gland, 15 Arteria abdominalis cranialis, 16 Stomach, 17 Liver (Lobus caudatus), 18 Kidney|
|Gray's||subject #117 406|
It is located approximately at the level of the twelfth thoracic vertebra (T12).
Strictly speaking, it is not an aperture in the diaphragm but an osseoaponeurotic opening between it and the vertebral column, and therefore behind the diaphragm; occasionally some tendinous fibers prolonged across the bodies of the vertebræ from the medial parts of the lower ends of the crura pass behind the aorta, and thus convert the hiatus into a fibrous ring.
The hiatus is situated slightly to the left of the middle line, and is bounded in front by the crura, and behind by the body of the first lumbar vertebra.
The Aorta does not pass through the aortic hiatus, rather, it passes posterior to it. The Azygos vein and thoracic duct pass through this opening.