It is located approximately at level of the tenth thoracic vertebra (T10). Actually, the esophagus (inside the esophageal hiatus) extends from cervical vertebra 6 to thoracic vertebra 7.
The esophageal hiatus is situated in the muscular part of the diaphragm at the level of the tenth thoracic vertebra, and is elliptical in shape. It is placed above, in front, and a little to the left of the aortic hiatus, and transmits the esophagus, the vagus nerves, and some small esophageal arteries. The right crus of the diaphragm loops around forming a sling around the diaphragm. Upon inspiration, this sling would constrict the diaphragm, forming an anatomical sphincter that prevents stomach contents from refluxing up the oesophagus when intra-abdominal pressure rises during inspiration.