Anatomical configuration of the spinal column in the supine position. I. A study using magnetic resonance imaging.

In order to clarify the anatomical configuration of the spinal column in the supine position, we have examined T1-weighted sagittal midline magnetic resonance images of the spinal column in 20 healthy volunteers (11 men, nine women) in the supine position. The mean maximum angles of decline of the lumbar spinal canal in men and women were 12.6 (SD 3.9) degrees and 13.4 (3.3) degrees in the cephalad direction, respectively. The maximum angles of incline of the upper thoracic spinal canal in men and women were 20.3 (4.0) degrees and 18.5 (2.5) degrees, respectively. The median highest points of the lumbar spinal canal in men and women were located at L4 (range L3-4 to L4) and L4 (L4), respectively. The lowest point of the thoracic spinal canal was located at T8 (T7-T9) in both men and women. We have demonstrated that both lumbar lordosis and thoracic kyphosis differ between individuals, particularly with respect to the lowest point of the thoracic spinal canal, which is located between T7 and T9.