On a contrast-enhanced axial CT of the chest at the level of T12, a triangular density is noted posterior to the crus of the diaphragm, between the crus and the vertebral body, containing fat and a longitudinal structure. This is the:
- A Aortic hiatus transmitting the aorta and thoracic duct ✓
- B Retrocrural space containing the azygos vein
- C Hiatus for the esophagus transmitting the vagus nerve
- D Caval opening transmitting the right phrenic nerve
Correct answer: A. Aortic hiatus transmitting the aorta and thoracic duct
Explanation
The aortic hiatus is at T12, posterior to the median arcuate ligament and between the crura, transmitting the aorta and thoracic duct. The esophageal hiatus is at T10, and the caval opening is at T8 in the central tendon. The retrocrural space is posterior to the crura but the aortic hiatus itself is the crural opening at T12.
Reference: Gray's Anatomy, 42nd ed.
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