Morphological Comparison of the Vertebrae in Humans and Some Other Mammals

The form of the human vertebral column is different from those of other mammals. The aim of this study was to determine the morphological characteristics of the vertebrae, as a first step toward revealing the relationship between form and function of the human vertebra in ordinary posture and movement. The materials were vertebrae from the 3rd cervical to the last lumber vertebra of 52 modern Japanese humans (26 males, 26 females), 5 chimpanzees, 6 macaques (Japanese monkeys) and 6 Japanese serows. Measured items were ventral and dorsal heights, superior and inferior sagittal diameters, as well as superior and inferior transverse diameters of the vertebral bodies (SHI et al. 1995); sagittal and transverse projected diameters of vertebral formina, the length and cranial inclination angle of the spine. The following results were indicated for the human vertebra. The foraminal sagittal diameter shows little variation from the 3rd cervical to the last lumber vertebrae. The foraminal transverse diameters in cervical and lumber regions are markedly larger than those in most of the thoracic region. The spine of the 6th thoracic vertebrae is the longest. The spinal cranial inclination angle of the 7th (the 6th in females) thoracic vertebra is the smallest. The projected lengths of spine at the transitional region of the cervical and thoracic vertebrae, and the lumber region are always longer than those in other parts.