In the bodies of humans, as well as many animals, the torso or trunk, is the area of the body that contains the chest and abdomen, and includes the area of the body between the neckline and pelvis, excluding limbs. The torso includes internal and external features of the human body, such as important organs like the kidney, heart, lungs and liver, the skin and several types of muscles. These skeletal components work together to carry out many critical life functions, such as respiration, digestion and reproduction.
The trunk forms the central area of human and animal bodies, which typically appears as a square or rectangular area, but exists in circle form in some species, such as starfish. Regardless of shape, the torso region is generally separated into two parts: the chest and abdomen. Within the chest are circulatory organs, such as the heart and lungs. The abdomen, which forms the lower part of the torso, contains digestive organs and the urinary system. The two areas of the torso are physically separated by a barrier called the diaphragm, which is a dense, fibrous muscle comprised of many layers. Some skeletal components traverse both segments of the torso, such as the spinal cord and several large muscles, and help the body to move and bend.