The first cervical vertebra has an inferior articulating surface but, as it does not restrict lateral or posterior translation, is not always considered a proper zygoma[10][11] (zygoma is Greek for "yoke," i.e. something that restrains movement). In the lumbar spine, facets provide about 20 percent of the twisting stability in the low back. Each facet joint is positioned at each level of the spine to provide the needed support especially with rotation.