Gradient of mineral contents of vertebral column with special reference to intervertebral discs.

To study quantitatively the mineral elements in the vertebral column, we examined the vertebrae and intervertebral discs resected from three normal cadavers which died at middle age, by inductively coupled plasma atomic emission spectrometry. The relative contents of calcium, phosphorus, and sodium in vertebrae were high in the order from cervical to lumbar vertebrae. The ratios of calcium per phosphorus were 1.80 +/- 0.25 in cervical vertebrae, 1.59 +/- 0.22 in thoracic vertebrae, and 1.23 +/- 0.24 in lumbar vertebrae. The ratio of cervical vertebrae was the highest among them. In regard to intervertebral discs, both the relative contents of calcium and phosphorus were very much higher in the intervertebral discs between the 4th and 8th thoracic vertebrae than the others.