Spinal nerve levels. Labelled colour-converted sagittal magnetic resonance imaging (MRI) scan of a human head and torso, showing the levels of innervation by the spine as used by chiropractors. The image plane passes vertically through the centre of the body, with the front of the body at left. The regions (from top) are: cervical, thoracic, lumbar spine, and sacral. The vertebrae are labelled: cervical (C1-C7), thoracic (T1-T12), lumbar (L1-L5), and sacral (S1-S5). The labels for the levels reference many body organs, including the brain, eyes, ears, teeth, joints, thyroid, heart, lungs, liver, stomach, intestines, pancreas, spleen, kidneys, sex organs, uterus, bladder, prostate, and hips.