Abdominal scan. Coloured magnetic resonance imaging (MRI) scan of the abdomen of a woman in coronal (frontal) section. The vertebrae (green, upper centre to centre) which form the spinal column are separated by the cartilaginous intervertebral discs (purple). Below the spine is the bladder (dark purple, lower centre), which receives urine from the kidneys (one seen at upper left, blue oval) and stores it before it is excreted. On either side of the bladder lie the femurs (thigh bones, green/purple, lower left and lower right, running to bottom). These are the longest and strongest bones in the body.