The abdomen is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. The area occupied by the abdomen is called the abdominal cavity. In arthropods, it is the posterior tagma of the body; it follows the thorax or cephalothorax.
The human abdomen and organs which can be found beneath the surface
(Left) Henry Gray (1825–1861). Anatomy of the Human Body. (Right) A male abdomen.
Side-by-side comparison of quadrants and regions.
The pelvis is the lower part of the trunk, between the abdomen and the thighs, together with its embedded skeleton.
The same human pelvis, front imaged by X-ray (top), magnetic resonance imaging (middle), and 3-dimensional computed tomography (bottom)
The pelvic girdle of the dinosaur Falcarius utahensis
Diameters of pelvic inlet