Aortic hiatus

The aortic hiatus is a midline[1]: 185  opening in the posterior part of the diaphragm giving passage to the descending aorta as well as the thoracic duct, and variably the azygos and hemiazygos veins.[2] It is the lowest and most posterior of the large apertures.

Aortic hiatus
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 coeliaca, 7 Arteria phrenica caudalis, 8 Ganglion coeliacum, 9 Plexus coeliacus, 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
Details
Identifiers
Latinhiatus aorticus
TA98A04.4.02.010
TA22342
FMA58288
Anatomical terminology

It is located at the level of the inferior border of the twelfth thoracic vertebra (T12),[2] posterior to the median arcuate ligament[2][1]: 185  between the two crura of the diaphragm.[2]

Structure

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 (meaning that diaphragmatic contractions during respiration do not directly affect aortic blood flow[3]).

The hiatus is situated slightly to the left of the midline, and is bound anteriorly by the crura, and posteriorly by the body of the first lumbar vertebra.

Occasionally some tendinous fibers prolonged across the bodies of the vertebræ from the medial parts of the inferior ends of the crura pass posterior to the aorta, and thus convert the hiatus into a fibrous ring.

Contents

The aorta is situated on the left, the thoracic duct in the middle, and the azygos vein on the right.[1]: 185  The hemiazygos vein may pass through the aortic hiatus[2] or may pass through the diaphragm independently through its own foramen in the left crus.[1]: 186 

Additional images
  • The thoracic and right lymphatic ducts.
    The thoracic and right lymphatic ducts.

References
  1. Sinnatamby, Chummy S. (2011). Last's Anatomy (12th ed.). ISBN 978-0-7295-3752-0.
  2. Moore, Keith L.; Dalley, Arthur F.; Agur, Anne M. R. (2017). Essential Clinical Anatomy. Lippincott Williams & Wilkins. p. 536. ISBN 978-1496347213.
  3. Moore, Keith L.; Dalley, Arthur F.; Agur, Anne M. R. (2017). Essential Clinical Anatomy. Lippincott Williams & Wilkins. p. 536. ISBN 978-1496347213.


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