Sacrum
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The sacrum, in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae between ages 18 and 30.
Anterior view of a 3D volume-rendered CT reconstruction displaying the lumbosacral junction, illustrating the articulation of the fifth lumbar vertebra onto the base of the sacrum.
Sacrum. Pelvic surface.
Sacrum. Dorsal surface.
Sacrum (not labeled) seen on the right with sacral nerves, median sacral artery, and rectum on the lower left.
Lumbar vertebrae
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The lumbar vertebrae are located between the thoracic vertebrae and sacrum. They form the lower part of the back in humans, and the region of the spine between the rib cage and pelvis in quadrupedal m
Sacrum
…sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua. The sacrum has three different surfaces which are shaped to…
Lumbar vertebrae
Sacralization of the L5 vertebra is seen at the lower right of the image.
Congenital block vertebra of the lumbar spine. CT volume rendering.