T8–T9 nucleus !
The nucleus pulposus is the soft, gel-like centre of the T8-T9 disc in the mid-back; it works like a water cushion that spreads the load.
Official name: T8-T9
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What it is
The soft, gel-like centre (nucleus pulposus) of the T8–T9 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 facts
- Where
- Centre of the T8–T9 disc, slightly toward the back, inside the annulus fibrosus
- Function
- Notochord-derived gel (about 70–90% water, proteoglycans); turns axial load into annulus tension; small in thin thoracic discs, herniation rare
Relations
- Above
- Endplate of T8, through which a Schmorl node can form
- Behind
- Back of the annulus fibrosus and the posterior longitudinal ligament, then the spinal cord
Examination
- Forward bend seen from the side: a sharp, rigid hump that does not straighten on arching back or lying prone fits Scheuermann kyphosis; a postural round back corrects
On imaging
On MRI a Schmorl node is a rounded pit in the endplate continuous with the disc; a recent one may show swelling (oedema) of the surrounding marrow.
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
- Scheuermann kyphosis is commonly defined by wedging of 5° or more in three neighbouring vertebrae, often near the apex around T7–T9, with irregular endplates and Schmorl nodes
- In a teenager who is still growing, Scheuermann kyphosis is usually managed with exercise and sometimes a brace; surgery is kept for large, painful or progressing curves
Development
During growth the cartilage endplates also act as growth plates for the vertebral bodies. In Scheuermann disease the front of these plates grows less during the adolescent spurt, the bodies become wedged, and nucleus can break into them as Schmorl nodes.
Test yourself
Think of the answer, then tap the question to see it.
What is a Schmorl node, typical near the T8–T9 nucleus?
Nucleus pushed vertically through the endplate into the vertebral body; such nodes cluster in the lower thoracic spine and are typical of Scheuermann disease.
How does a Schmorl node from the T8–T9 nucleus look on MRI?
A rounded pit in the endplate continuous with the disc; a recent one may show oedema of the surrounding marrow.
What holds the water in the T8–T9 nucleus pulposus?
Proteoglycans: the notochord-derived gel is about 70–90% water held by them.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- nucleus pulposus T8-T9 TA2 1686
- Official Spanish (DeCS)
- Núcleo pulposo T8-T9 DeCS D000070614
- English (TA2)
- T8-T9
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Back, Nucleus Pulposus; Anatomy, Back, Intervertebral Discs; 7.3 The Vertebral Column (OpenStax (Rice University), 2022) · adapted, CC BY 4.0.
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Representative model, for educational purposes only.
