Corpus: Aortic hiatus

The aortic hiatus is a recess in the diaphragm through which the aorta and the thoracic duct pass from the chest cavity into the abdominal cavity.

The aortic hiatus is the most caudal and dorsal opening of the diaphragm. It lies slightly to the left of the median plane - approximately at the level of the 12th thoracic vertebra - and is crossed ventrally by the two crura of the diaphragm and by the median arcuate ligament. The aortic hiatus marks the border between the thoracic aorta and the abdominal aorta.

More precisely, the aortic hiatus is not a recess in the diaphragm, but an opening between the diaphragmatic aponeurosis and the spinal column, which lies "behind" the diaphragm. This means that diaphragmatic contractions have no disruptive effect on the aortic lumen. Occasionally, some fibres from the medial sides of the two crura pass behind the aorta to form a complete fibrous ring.

• Podcast image source: © Midjourney