Which anatomical structure acts as the divider between the thorax and abdomen?

The diaphragm serves as the divider between the thoracic cavity (thorax) and the abdominal cavity. This muscular structure is crucial for respiratory function, as it contracts and flattens to allow air to enter the lungs and relaxes to help expel air. Its position separates the heart and lungs located in the thorax from the various organs that reside in the abdomen, such as the stomach, liver, and intestines. The diaphragm's role is essential not only in facilitating breathing but also in maintaining the structural integrity of these two distinct body cavities. In contrast, while the liver, heart, and lungs are all vital organs, they do not fulfill the anatomical function of dividing the thorax and abdomen.