the axis of the skeleton situated dorsally in the median plane and supporting the skull superiorly in humans, while inferiorly it ends in the coccyx and is joined to the hip bones at the sacroiliac joints through which the weight of the body is transmitted to the lower limbs, on moodustunud reastikku paiknevatest paaritutest selgroolülidest: kaela-, rinna- , nimme-, ristluu- ja sabalülidest