Structures · Cord and roots
Conus medullaris
The tapered lower end of the spinal cord. Its vertebral level differs between people; in the largest study we cite it was most often at L1 or the T12–L1 disc.
At a glance
- In this model
- Ends opposite L1 (vertebral level)Measured on one model: the Visible Human male, imaged as a supine cadaver. Not a normal range. Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014
How much it varies between people
Percent of 629 adults by the vertebral level opposite the conus; highlighted, this model. Nakashima et al. 2021, Results, first paragraph.
More on variationWhat the sources say
“Multiple regression analysis showed that the pelvic incidence (p < 0.0001) and height (p < 0.0001) were significant factors affecting the conus medullaris level.” Nakashima et al. 2021
Read more
- Conus medullaris and cauda equina
Where the spinal cord ends and what fills the canal below it. Why the cord stops near L1, how much that varies, and how the lower nerve roots travel down as the cauda equina.
- Meninges and cerebrospinal fluid
The three membranes around the brain and cord and the fluid between them. What dura, arachnoid and pia are, where cerebrospinal fluid is made and where it goes, and why a lumbar puncture is done low in the back.
- The spinal cord
The part of the central nervous system inside the vertebral column. How it is built from grey horns and white columns, why it is shorter than the column, and how its regions are named.
- Vertebral and spinal cord levels
Why "L1" can mean two different places. The vertebrae and the spinal cord segments have their own numbering, and below the neck they drift apart, because the column grows longer than the cord.
For learning only. Levels and sizes vary between people; nothing here describes a particular person or gives medical advice. Sources: Nakashima et al. 2021; Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014.