Sacrum with completely sacralized L5 vertebra via A.R. Titlebaum

Tales From The Grave: Sacralization of the Lumbar

This is a small series that will focus on some of the types of trauma, pathology and degeneration I examined will at the Odyssey Field School in Cyprus. Please note that the images included are NOT from the actual cases that my peers and I worked on. However, the images included are accurate representations of the cases analyzed.

Sacralization of the Lumbar

Your spine, which is a part of our axial skeleton,  is made up of 33 individual vertebrae, on average. I say “on average” because *in my Ice-T voice* I’ve seen some things. Through my few years of examining human remains, occasionally, I’ve seen a spine that would perfectly articulate, or fit together, but there was a vertebra “missing”. I’m not talking fused or connected to another one. It was just absent.

However, sacralization is not a missing spine bone, but one that is fused to another.

You may be able to guess that sacralization will likely have to do with the sacrum. The sacrum is made up of five vertebrae that fuse into a single piece that articulates (joins) with the fifth lumbar vert.

Sacrum Illustration from U.S. National Library of Medicine

There are no tricks there. Looking at the sacrum, it is made up of five sacral vertebrae that are fused, making up one piece. So, now if I say “sacralization of the lumbar” chances are (I hope) that you have figured out or took a guess that the phrase refers to the sacrum and lumbar vertebrae fusing together.

We have 5 lumber, lower back, vertebrae. The L5 (fifth lumbar bone) is usually the one

Vertebral column  Image via Britannica

that would be affected by sacralization as it sits directly on the sacrum. Below you can see the L5 and sacrum as they would appear separately, and then an image of the two fused together.

The L5 and sacrum can be either fully or partially fused by the transverse process and or illium.



Partial and complete fusion of the L5 on one side via Netter’s Atlas of Human Anatomy


Sacralization occurs in the embryo so it is present from the time the individual is born. While some people who have this anomaly may experience back pain over time, some may not. In 1917, a physician named Mario Bertolotti is understood to be the first to associate sacralization with lower back pain, but this finding has been debated.

Image via Basic Medical Key

Some patients who have this fusion have reported nerve irritation, limited movement, and effects to their center of gravity. While a limited range of motion and pain are associated with lumbar sacralization, how it manifests and what an individual will experience due to the fusion will vary.

Sacrum with completely sacralized L5 vertebra via A.R. Titlebaum



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