In general, the clefts in the diaphragm are the aortic foramen, the esophageal cleft, and the vena cava foramen. 1. Aortic foramen: The aortic foramen is located anterior to the 12 thoracic vertebrae, through which the aorta and thoracic duct can pass. 2. Esophageal hiatus: The esophageal hiatus is located mainly at the level of the 10th thoracic vertebra, and the vagus nerve and esophagus pass through the esophageal hiatus. 3. Foramen ovale: The foramen ovale is located mainly at the level of the 8th thoracic vertebra and the inferior vena cava passes through it. The diaphragm is a thin, flat, upwardly elevated muscle that lies between the abdominal and thoracic cavities and forms the floor of the thoracic cavity and the roof of the abdominal cavity. The diaphragm is the main respiratory muscle, which facilitates expiration when it relaxes and inhalation when it contracts. When the diaphragm and the abdominal muscles contract at the same time, it increases abdominal pressure, which can assist in activities such as sneezing, coughing, and vomiting.