The abdomen is the part of the body that lies between the chest and the thigh and encloses the ureters, intestines, liver, anus, bladder, gallbladder, and reproductive system outside the breast. It is also called the belly or venter. In humans, and in many other vertebrates, it is the region between the thorax and the pelvis (Separating the thoracic cavity and the abdominal cavity is the thoracic diaphragm). In fully developed insects, the abdomen is the third (or posterior) segment, after the head and thorax.