Final answer:
The esophagus passes through the esophageal hiatus to enter the abdominal cavity. It is a specific opening in the diaphragm for the esophagus and attached nerves.
Step-by-step explanation:
The opening in the diaphragm through which the esophagus passes to enter the abdominal cavity is called the esophageal hiatus.
The esophagus is a muscular tube approximately 25 cm (10 in) in length and runs a mainly straight route through the mediastinum of the thorax.
When it needs to enter the abdomen to connect to the stomach, it penetrates the diaphragm through the esophageal hiatus. This hiatus is one of three major openings in the diaphragm, with the other two being the caval opening for the inferior vena cava and the aortic hiatus for the aorta, thoracic duct, and azygous vein.