The spondylolysis in Thais.

93 Thai skeletons, 49 male and 44 female, or 465 lumbar vertebrae, 245 males and 220 females, were studied for Spondylolysis. Spondylolysis was found in 11 of 465 lumber vertebrae, 5 male and 6 female. It occurred at the third lumbar vertebra in 1 case, at the fourth lumbar vertebra in 4 cases and at the fifth lumber vertebra in 6 cases. In Thais, spondylolysis has been classified into three patients, the defect occuring bilaterally at the lamina in 9 cases, the defect at the lamina being unilateral in 1 case and the defect at the spine called unfused spine (Spinabifida) in 1 case.

Pattern of lumbar plexus in Thais.

A Study on the pattern of lumbar plexus was performed in 83 plexus; 42 right and 41 left. The lumbar plexus, generally is formed by the ventral rami of the first lumbar spinal nerve to the fourth lumbar spinal nerve in 68.7 percent. There is no difference in origin of lumbar plexus between right and left side and between sexes. In 75.0 percent of the iliohypogastric nerve is formed by the ventral rami of the first lumbar spinal nerve. In 81.9 percent of the ilio-hypogastric nerve is formed by the ventral rami of the first lumbar spinal nerve. In 74.7 percent of the genitofemoral nerve is formed by the ventral rami of the first and second lumbar spinal nerve. In 71.0 percent of the lateral cutaneous nerve of thigh is formed by the ventral rami of the second and third lumbar spinal nerve. In 89.2 percent of the femoral nerve is formed by the second, third and fourth lumbar spinal nerve. In 90.4 percent of the obturator nerve is formed by the second, third and fourth lumbar spinal nerve.