[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–L2 nucleus [Joints and ligaments](https://durgical.com/en/anatomy/system/joints-and-ligaments/) · [Spine](https://durgical.com/en/anatomy/region/spine/) # L1–L2 nucleus The nucleus pulposus is the soft, gel-like centre of the [L1-L2](https://durgical.com/en/anatomy/l1-l2/) disc in the lower back; it works like a water cushion that spreads the load. Official name: L1-L2 [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=spine&select=nucleus_l1_l2&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The soft, gel-like centre (nucleus pulposus) of the L1–L2 disc. ## What it does Works like a water cushion: it turns pressure from above into outward push on the fibre ring, spreading the load. It is under the most pressure when you bend forward and lift. ## Key points - Schmorl nodes (nucleus pushed vertically through the endplate into the vertebral body) are most frequent in the lower thoracic and upper lumbar [spine](https://durgical.com/en/anatomy/region/spine/), L1–L2 included; most are incidental - A central L1–L2 fragment can reach the [conus medullaris](https://durgical.com/en/anatomy/conus-medullaris/), so cord and root signs can mix ## Key facts **Where** Centre of the L1–L2 disc, slightly toward the back, inside the annulus fibrosus **Function** Notochord-derived gel (about 70–90% water, proteoglycans); turns axial load into annulus tension; herniates posterolaterally toward the L2 root ## Relations **Behind** Back of the annulus and the [posterior longitudinal ligament](https://durgical.com/en/anatomy/posterior-longitudinal-ligament/), then the dural sac with the tip of the conus (usually near L1–L2) and the [cauda equina](https://durgical.com/en/anatomy/cauda-equina/) **Lateral** Annulus with the [psoas major](https://durgical.com/en/anatomy/psoas-major/) arising from the sides of the disc and bodies; the L1 root leaves through the foramen at this level ## Examination - L2 root: weak hip flexion (iliopsoas) and numbness over the upper front of the thigh; the cremasteric reflex (L1–L2) may be reduced ## On imaging A Schmorl node is a rounded dent in the endplate continuous with the disc on MRI or CT; a recent one may show bright marrow oedema around it on T2 or STIR. ## Common problems - Squeezes out through a tear in the ring (herniation), usually backward and to one side, toward a nerve root. - Loses water with age, so the disc gets thinner and stiffer. ## How it is diagnosed On MRI a healthy nucleus is bright on T2 images; a worn one turns dark ('black disc'). ## Treatment - In a microdiscectomy only the loose piece that has pushed out is removed; most of the disc stays. ## Clinical notes - Several Schmorl nodes with wedged vertebrae and irregular [endplates](https://durgical.com/en/anatomy/vertebral-endplates/) in a teenager suggest Scheuermann disease, which at the thoracolumbar junction can cause back pain - Upper lumbar herniations are uncommon next to those at the two lowest levels; they tend to occur in older people and their thigh pain can be taken for hip disease - Tuberculous spondylitis (Pott disease) favours the lower thoracic and upper lumbar spine; compared with pyogenic infection it tends to spare the disc longer and to form large paraspinal abscesses ## Test yourself Think of the answer, then tap the question to see it. ## Where are Schmorl nodes from nuclei such as L1–L2 most frequent, and are they usually significant? In the lower thoracic and upper lumbar spine, L1–L2 included; most are incidental. ## Why can a central L1–L2 nucleus fragment give mixed cord and root signs? It can reach the conus medullaris, which ends near this level, as well as the roots around it. ## Which findings around the L1–L2 nucleus suggest Scheuermann disease in a teenager? Several Schmorl nodes with wedged vertebrae and irregular endplates; at the thoracolumbar junction it can cause back pain. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/l1-l2-spine-and-pelvis/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** nucleus pulposus L1-L2 TA2 1686 **Official Spanish (DeCS)** Núcleo pulposo L1-L2 DeCS D000070614 **English (TA2)** L1-L2 ## Related - [L1–L2 disc](https://durgical.com/en/anatomy/l1-l2/) - [L1 vertebra](https://durgical.com/en/anatomy/lumbar-vertebra/) - [L2 vertebra](https://durgical.com/en/anatomy/lumbar-vertebra-spine-and-pelvis/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=56248&filter=ths_termall&q=N%C3%BAcleo%20Pulposo); [Anatomy, Back, Nucleus Pulposus](https://www.ncbi.nlm.nih.gov/books/NBK535373/); [Anatomy, Back, Intervertebral Discs](https://www.ncbi.nlm.nih.gov/books/NBK470583/); [7.3 The Vertebral Column](https://openstax.org/books/anatomy-and-physiology-2e/pages/7-3-the-vertebral-column) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). ## **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/l1-l2-spine-and-pelvis/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/l1-l2-spine-and-pelvis/