Structure of<unk>  shown using a 3D medical animation still shot The<unk> , or simply the<unk>  (), is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the<unk>  cavity. The<unk>  is the most important muscle of respiration, and separates the<unk>  cavity, containing the heart and lungs, from the abdominal cavity: as the<unk>  contracts, the volume of the<unk>  cavity increases, creating a negative pressure there, which draws air into the lungs. Its high oxygen consumption is noted by the many mitochondria and capillaries present; more than in any other skeletal muscle. The term<unk>  in anatomy, created by Gerard of Cremona, can refer to other flat structures such as the urogenital<unk>  or pelvic<unk> , but "the<unk> " generally refers to the<unk> . In humans, the<unk>  is slightly asymmetric—its right half is higher up (superior) to the left half, since the large liver rests beneath the right half of the<unk> . There is also speculation that the<unk>  is lower on the other side due to heart's presence. Other mammals have<unk> s, and other vertebrates such as amphibians and reptiles have<unk> -like structures, but important details of the anatomy may vary, such as the position of the lungs in the<unk>  cavity.
Thoracic diaphragm
Diaphragm 
Thoracic inlet
Boracic lint
Cervical rib
Subclavian loop
Pleural cavity
Lung cavity