[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Spine](https://durgical.com/en/anatomy/region/spine/) › L1 vertebra [Skeletal system](https://durgical.com/en/anatomy/system/skeletal-system/) · [Spine](https://durgical.com/en/anatomy/region/spine/) # L1 vertebra L1 is the first lumbar (lower-back) vertebra, with a large weight-bearing body; the [spinal cord](https://durgical.com/en/anatomy/spinal-cord/) ends at about this level. Official name: L1 [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=spine&select=l1&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The L1 lower-back vertebra, with a large body built to carry weight. The spinal cord ends at about this level. ## What it does Carries the weight of the upper body and, with the disc and facet joints, lets the lower back bend forward and back. ## Key points - The adult cord ends at about the [L1–L2 disc](https://durgical.com/en/anatomy/l1-l2/); a burst fracture of L1 can damage the conus medullaris (conus syndrome) rather than single roots - Transpyloric plane at L1: pylorus, neck of the [pancreas](https://durgical.com/en/anatomy/pancreas/), renal hila, origin of the superior mesenteric artery, [gallbladder](https://durgical.com/en/anatomy/gallbladder/) fundus and ninth [costal cartilages](https://durgical.com/en/anatomy/costal-cartilage/) - T12 and L1 are the vertebrae most often fractured in the thoracolumbar spine ## Key facts **Joints with** T12 above and L2 below (intervertebral discs, facet joints) **Landmarks** Large kidney-shaped body; no costal facets or transverse foramina; mammillary processes; transpyloric plane; conus medullaris ends near L1–L2 ## Relations **In front** Crura of the [diaphragm](https://durgical.com/en/anatomy/diaphragm/) on each side of the body; the [abdominal aorta](https://durgical.com/en/anatomy/abdominal-aorta/) with the [superior mesenteric artery](https://durgical.com/en/anatomy/superior-mesenteric-artery/) leaving at about L1; the [cisterna chyli](https://durgical.com/en/anatomy/cisterna-chyli/) to the right of the aorta; the [inferior vena cava](https://durgical.com/en/anatomy/inferior-vena-cava/) farther right **Lateral** [Psoas major](https://durgical.com/en/anatomy/psoas-major/) starts from the bodies and discs; the [kidneys](https://durgical.com/en/anatomy/kidney/) lie in front of the transverse processes, their hila near this level **Behind** Broad, horizontal [spine](https://durgical.com/en/anatomy/region/spine/) under the [thoracolumbar fascia](https://durgical.com/en/anatomy/thoracolumbar-fascia/); erector spinae and [multifidus](https://durgical.com/en/anatomy/multifidus-muscles/) in the groove beside it **Contents** [Conus medullaris](https://durgical.com/en/anatomy/conus-medullaris/) with the sacral cord segments, and the start of the [cauda equina](https://durgical.com/en/anatomy/cauda-equina/) ## How to find it The spine is counted up from L4 on the iliac crest line, or down from the twelfth rib. In front, the transpyloric plane sits midway from the jugular notch to the top of the [pubic symphysis](https://durgical.com/en/anatomy/pubic-symphysis/). ## On imaging MRI shows where the conus ends; a conus below L2 in a child suggests a tethered cord. On CT, burst fractures here are judged by canal narrowing and loss of body height. ## Common problems - Disc degeneration and herniation at [L4-L5](https://durgical.com/en/anatomy/l4-l5/), the most common level for back and leg pain. - Degenerative spondylolisthesis: L4 slips forward on L5, often with stenosis (more common in women over 50). - Spinal stenosis: the canal narrows from disc bulging, facet arthritis and a thick [ligamentum flavum](https://durgical.com/en/anatomy/ligamenta-flava/). - Compression fractures from osteoporosis or injury. ## How it is diagnosed X-rays (standing, and bending forward and back) show alignment and slipping. MRI shows discs, nerves and stenosis. CT shows bone detail. ## Treatment - Most back pain improves with staying active, physical therapy and pain medicine. - Stenosis with leg pain when walking that does not improve: decompression (laminectomy). - Slipping with instability: decompression plus fusion with screws, rods, a cage and bone graft. ## Clinical notes - Conus syndrome versus cauda equina syndrome: the conus gives early, symmetric bladder and bowel loss and saddle numbness with mixed upper and lower motor neuron signs; the cauda equina gives asymmetric root pain and lower motor neuron weakness - Tethered cord: the conus sits abnormally low, held by a thick [filum terminale](https://durgical.com/en/anatomy/filum-terminale-internum/) or a lipoma; pain, gait changes and bladder problems appear with growth ## Development At birth the cord ends lower, at about L2–L3, and reaches its adult level in early infancy because the spine grows faster than the cord. ## Related conditions - [Multiple myeloma](https://durgical.com/en/conditions/multiple-myeloma/) - [Osteoporotic vertebral compression fracture](https://durgical.com/en/conditions/osteoporotic-vertebral-compression-fracture/) - [Spinal tuberculosis (Pott disease)](https://durgical.com/en/conditions/spinal-tuberculosis/) - [Tuberculosis](https://durgical.com/en/conditions/tuberculosis/) - [Osteoporosis](https://durgical.com/en/conditions/osteoporosis/) - [Malignant spinal cord compression](https://durgical.com/en/conditions/malignant-spinal-cord-compression/) ## Test yourself Think of the answer, then tap the question to see it. ## At which level does the adult spinal cord end, and what does an L1 burst fracture risk? At about the L1–L2 disc; an L1 burst fracture can damage the conus medullaris (conus syndrome) rather than single roots. ## Which structures lie on the transpyloric plane at the L1 vertebra? The pylorus, the neck of the pancreas, the renal hila, the origin of the superior mesenteric artery, the gallbladder fundus and the ninth costal cartilages. ## How does conus syndrome at the L1 vertebra differ from cauda equina syndrome? Conus: early, symmetric bladder and bowel loss and saddle numbness with mixed upper and lower motor neuron signs. Cauda equina: asymmetric root pain and lower motor neuron weakness. ## What does a conus medullaris ending below L2 in a child suggest? A tethered cord, held low by a thick filum terminale or a lipoma. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/lumbar-vertebra/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** vertebra lumbalis I TA2 1068 **Official Spanish (DeCS)** Vértebra lumbar L1 DeCS D008159 **English (TA2)** L1 ## Related - [T12–L1 disc](https://durgical.com/en/anatomy/t12-l1/) - [L1–L2 disc](https://durgical.com/en/anatomy/l1-l2/) - [Lumbar arteries](https://durgical.com/en/anatomy/lumbar-arteries/) - [Anterior longitudinal ligament](https://durgical.com/en/anatomy/anterior-longitudinal-ligament/) - [Endplates](https://durgical.com/en/anatomy/vertebral-endplates/) - [Low-back facet joints](https://durgical.com/en/anatomy/zygapophysial-joints-spine-and-pelvis/) - [Mid-back facet joints](https://durgical.com/en/anatomy/zygapophysial-joints-spine-and-pelvis-facet-joints-thoracic/) - [Interspinales](https://durgical.com/en/anatomy/interspinales-muscles/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=8334&filter=ths_termall&q=V%C3%A9rtebras%20Lumbares); [Anatomy, Back, Lumbar Spine](https://www.ncbi.nlm.nih.gov/books/NBK557616/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/lumbar-vertebra/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/lumbar-vertebra/