The primary purpose of the diaphragm in the human body is to facilitate breathing. This dome-shaped muscle lies at the base of the thoracic cavity, separating the chest from the abdominal cavity. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity, which lowers the pressure inside and allows air to be drawn into the lungs (inhalation). Conversely, when it relaxes, the diaphragm moves upward, decreasing the thoracic cavity's volume and forcing air out of the lungs (exhalation). The diaphragm is essential for efficient respiration and serves as a major muscle of inspiration.