lumbar spine

https://doi.org/10.1351/goldbook.11856
Portion of the vertebral column of the lower back between the thoracic spine and sacrum, in humans consisting of five vertebrae designated L1 to L5.
Source:
PAC, 2015, 87, 841. (IUPAC Glossary of terms used in neurotoxicology (IUPAC Recommendations 2015)) on page 878 [Terms] [Paper]