The authors dissected a 5-year-old male baboon and examined the
structure and bone mineral density (BMD) of the vertebrae. The baboon backbone
consisted of 7 cervical, 12 thoracic, 7 1umbar, 3 sacral, and 19 coccygeal vertebrae. It
was observed that long accessory processes were present in the 10th-12th thoracic and
the lst-5th lumbar vertebrae. The superior articular process was held between the
accessory and inferior articular processes of the adjacent vertebra. Therefore, the rotary
movement of the vertebral column was restricted in the range between the 10th thoracic
and 5th 1umbar vertebrae. Regarding the intervertebral joint, the position of axis for
rotation was shifted from ventral to dorsal direction on the superior and inferior views of
the 10th thoracic vertebra. The average BMD of the vertebrae was the highest in the
cervical vertebrae, and decreased in the order of the lower thoracic, lumbar, and upper
thoracic vertebrae
