The diaphragm divides the thoracic and the abdominal cavities. The lower esophagus lies behind the heart and curves in front of the thoracic aorta. The muscle lies at the junction of the thoracic and lumbar regions. It is divided into cervical, thoracic and abdominal parts. Better results are only in uncomplicated, elective descending thoracic and infrarenal aorta. The abdomen and the thorax with its thoracic appendages develop later. The primary curves (thoracic and sacral curvatures) form during fetal development. Ribs are found exclusively on the thoracic vertebrae. Both sexes have two thoracic and two abdominal teats. The number of thoracic vertebrae varies considerably across the species. Musician Isaac Hanson had a pulmonary embolism as a consequence of thoracic outlet syndrome. Its most prominent point behind corresponds to the spinous process of the seventh thoracic vertebra. In aggressive encounters, the black patch near the thoracic and lumbar vertebrae is erected. Conversely, a vomit occurs with "increased" thoracic and abdominal pressure. Najarian was a pioneer in thoracic transplant surgery.