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Robotic Spine Universe

Structures · Vertebrae

L1 vertebra

Vertebra 1 of the lumbar (lower back) spine. This page uses the vertebral level system; the cord segments that lie opposite it have different names.

Show in the 3D spineSee what it connects to in the body

At a glance

Level system
L1 vertebra (vertebral level)
Cord segments opposite its body
L5 to S3Model mapping (PAM50 cord in this column); varies between people. Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014
Canal, front to back × side to side
15.3 × 25.8 mmMeasured on one model: the Visible Human male, imaged as a supine cadaver. Not a normal range
T12 nerve
The T12 nerve exits between the T12 vertebra and the L1 vertebra, below the T12 vertebra.Betts et al. 2022, §13.4
L1 nerve
The L1 nerve exits between the L1 vertebra and the L2 vertebra, below the L1 vertebra.Betts et al. 2022, §13.4

What the sources say

“The lower back contains the L1–L5 lumbar vertebrae.” Betts et al. 2022, §7.3
“Lumbar Vertebrae Lumbar vertebrae carry the greatest amount of body weight and are thus characterized by the large size and thickness of the vertebral body ( Figure 7.28 ).” Betts et al. 2022, §7.3

Connections to the rest of the body

  • Muscle attachments

    Segmental muscles join neighbouring vertebrae

    The smallest back muscles span a single joint, from one vertebra to the next.

    Betts et al. 2022, §11.3 · Show on the body

  • Muscle attachments

    The diaphragm anchors to the lumbar spine

    Behind, the breathing muscle takes origin from the lumbar vertebrae and the 12th ribs; in front, from the sternum and lower ribs.

    Betts et al. 2022, §11.4 · Show on the body

  • Arterial supply

    Lumbar arteries supply the lower back and the cord

    Four pairs of lumbar arteries leave the abdominal aorta beside the lumbar vertebrae; they are the lower counterparts of the intercostal arteries.

    Betts et al. 2022, §20.5 · Show on the body

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.

  • 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: Betts et al. 2022, §7.3; Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014; Betts et al. 2022, §13.4; Betts et al. 2022, §11.3; Betts et al. 2022, §11.4; Betts et al. 2022, §20.5.