The lumbar vertebrae consist of five vertebrae in your lower back, the largest of the vertebrae in your spine. The first of your lumbar vertebra articulates with your last thoracic vertebra (which we will discuss tomorrow) and your last lumbar vertebra articulates with the sacrum (see yesterday’s post). The lumbar are your largest vertebrae since they bear more weight than the others. (Quick note: this is another anatomical word derived from Latin so vertebra is the singular form, and for the plural you add an ‘a’ – vertebrae).
The spine is another place where we especially differ from our fellow primate cousins because – you guessed it – our bipedal mode of locomotion. While humans typically have 5 lumbar vertebrae, apes only possess three to four on average (Hsu et al. 2017). Given that we walk upright, the curvature in our spine differs from apes and monkeys that walk quadrupedally or swing in the trees. You can see in the rotating image above on the left that there is a slight concavity to the curve of our lumbar spine, this is referred to as a lordotic curve. As we will see later on, the cervical region has this same type of inward curvature. This lordotic curve evolved to help stabilize our spinal weight while walking on only two legs (Hsu et al. 2017). A study published in Nature suggests that human females especially evolved so that lordosis could increase during pregnancy to help account for the increased weight (Whitcome et al. 2007).
And that’s all for your lumbar vertebrae, come back tomorrow when we discuss the longest region of your spine, the thoracic region.
REFERENCES & MORE TO EXPLORE
Lumbar Vertebrae. KenHub Anatomy. Ferng & Mytilinaios. Last reviewed September 2020
Lumbar vertebra. eAnthro Digital Libraries. University of Texas-Austin.
The relationship between trunk muscle strength and flexibility, intervertebral disc wedging, and
human lumbar lordosis. Hsu et al. The Harvard Undergraduate Research Journal. 2017
Lower back pain linked to chimpanzee spine shape. BBC News. April 2015
Fetal Load and the Evolution of Lumbar Lordosis in Bidepal Humans. Whitcome et al. Nature. 2007