Description
The base of sacrum is the large, upper aspect of the bone. It is formed by the superior surface of the body and transverse processes of the first sacral vertebra. It consists of the ala, promontory, and superior articular processes of sacrum.
Its medially located articular facet articulates with the fifth lumbar vertebra, forming the lumbosacral joint.
The base of sacrum provides attachment sites for the iliolumbar ligament. In some individuals, the fifth lumbar vertebra can be partially or completely fused to the base of the sacrum, which is known as sacralization of the fifth lumbar vertebra.
