Abnormalities of the lumbar spine in respect to mechanical stability and functional capacity have been a matter of considerable importance to those concerned with industrial medicine. More recently they have assumed particular interest in the Armed Forces, for whom the correlation between structural variants of the spine and precipitation or development of “back pain” is a significant problem. The Normal Vertebra Embryology (1, 9): At the second week of fetal life, there are two centers of chondrification in each vertebral body and one in each half of the incomplete neural arch. At the tenth week, the body shows a single center of ossification (at times two centers may appear). Concurrently, each half of the neural arch shows a single center of ossification. At birth, each lateral half of the neural arch consists of a bony plate united by cartilage with the body of the vertebra. During the first year of life, the vertebral arch forms as a result of fusion of these plates and gives rise to the spinous proc...