All movements in the body are made possible by muscles, and respiratory movements are no exception. During inhalation, the diaphragm and intercostal muscles contract, raising the ribcage and increasing the space in the thorax, allowing the lungs to attract more air from outside the body. Exhalation is usually a passive movement that occurs as the diaphragm and intercostal muscles relax back to their original position, along with the elastic recoil of the lungs. When someone actively exhales air, the abdominal and intercostal muscles can contract to reduce the volume in the thoracic cavity. Sometimes, even the neck muscles join in to achieve this.