LATERAL BEND.

DIAGRAM 2.

DIAGRAM 3.

DIAGRAM 2. Deformation. Bend to side. Rib distortion on the convex side. Line of spinous processes makes one long curve. Retrogression of dorsal vertebræ.

DIAGRAM 3. Recovery from 2 without bend in spine (segmental). The only change here from deformation is the distortion of the chest wall with the accompanying retrogression of dorsal vertebræ. The lines a b and c d are gravitation lines drawn as lateral tangents to the chest walls and indicate the unequal distribution of the weight of the thorax with reference to the pelvis. Dotted line on the right indicates the contour which the thorax must approximate, to gain the easiest balance. Result in the spine must be either total bend or compound bend as indicated by either of the curves on the right.

DIAGRAM 4 A. Recovery from 2, where head, chest, and pelvis recover as one piece, accomplished by bending the knee. Rib distortion maintained. The line of the spinous processes is identical with that in Diagram 2.

DIAGRAM 4 B. Further recovery from 4 A (or follows 2 directly). Head and pelvis leveled, and equilibrated to thorax as shown by tangential lines. Result, a compound curve in spine.

DIAGRAM 4 C. Similar recovery from 4, the pelvis here being leveled without the bend in the dorso-lumbar spine, namely, by a twist.

DIAGRAM 6. Deformation. In this diagram besides the rib distortion, we assume an actual permanent bend in the dorsal spine, thus the convexity of the bend in itself becoming a factor in the approximation of the column to the lateral wall.

DIAGRAM 7. Recovery from 6, the bend of the dorsal spine being retained. The line ending at (a) indicates the original bend of 6 in the line of spinous processes. The line ending at (b) is the same after recovery but before the head is equilibrated. The two lines meeting join the present line of the spinous processes at the dorso-lumbar segment again showing where the greatest adaptability is. The equilibration of the head forms the curve in the cervical region.

TWIST.

A

B

DIAGRAM 8.

DIAGRAM 9.

DIAGRAM 8. Deformation. Twist of whole body from the feet.

DIAGRAM 9 A. Deformation continued from 8. Vertebral retrogression and rib distortion. Dorsal bodies are twisted with respect to the lumbar. Approximation of lateral rib wall to the column.

DIAGRAM 9 B. Recovery from 9 A with chest deformity partly maintained. This means an untwisting of the head and of the pelvis with respect to the dorsal region implying a dorsal curve.

DIAGRAM 10.

DIAGRAM 11.

DIAGRAM 12.

DIAGRAM 10. Deformation. Twist from pelvis.

DIAGRAM 11. Deformation of 10 continued, in which retrogression of the vertebræ has taken place.

DIAGRAM 12. Recovery from 11. The line ending at (a) indicates the direction of the spinous processes during deformation, branching from the present line of spinous processes at the dorso-lumbar section as with lateral bend, here again the region of greatest adaptability. Once more approximation of column and lateral rib wall is maintained.