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# T5–T6 nucleus

The nucleus pulposus is the soft, gel-like centre of the [T5-T6](https://durgical.com/en/anatomy/t5-t6/) disc in the mid-back; it works like a water cushion that spreads the load.

Official name: T5-T6

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## What it is

The soft, gel-like centre (nucleus pulposus) of the T5–T6 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

- In the mid-thoracic [spine](https://durgical.com/en/anatomy/region/spine/) a central fragment presses on the cord rather than on a root, and the canal has little room to spare

## Key facts

**Where**
Centre of the T5–T6 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

**Behind**
Back of the annulus fibrosus and the [posterior longitudinal ligament](https://durgical.com/en/anatomy/posterior-longitudinal-ligament/), then the [spinal cord](https://durgical.com/en/anatomy/spinal-cord/)

## Examination

- Vibration and joint position sense in the toes, with the Romberg test: their loss suggests that cord compression is affecting the dorsal columns

## On imaging

Calcium in the nucleus or in a herniated fragment shows on CT as dense white material; MRI can underestimate it.

## 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

- Thoracic disc myelopathy is often recognised late, because early stiffness, heavy legs or vague band pain is put down to other causes
- Loss of vibration and position sense in the legs also occurs in vitamin B12 deficiency and multiple sclerosis, which are ruled out when MRI shows no cord compression

## Development

Notochord remnants left in the spine can give rise to a chordoma, a slow-growing malignant tumour; most arise in the [sacrum](https://durgical.com/en/anatomy/sacrum/) or at the skull base, and few in the mobile spine.

## Test yourself

Think of the answer, then tap the question to see it.

## What does a central fragment of the T5–T6 nucleus press on?

The spinal cord rather than a root; the mid-thoracic canal has little room to spare.

## Which imaging best shows calcium in the T5–T6 nucleus or a herniated fragment?

CT, where it shows as dense white material; MRI can underestimate it.

## From which embryonic structure does the T5–T6 nucleus pulposus come?

The notochord: the nucleus is a notochord-derived gel, rich in water and proteoglycans.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
nucleus pulposus T5-T6 TA2 1686

**Official Spanish (DeCS)**
Núcleo pulposo T5-T6 DeCS D000070614

**English (TA2)**
T5-T6

## Related

- [T5–T6 disc](https://durgical.com/en/anatomy/t5-t6/)
- [T5 vertebra](https://durgical.com/en/anatomy/t5/)
- [T6 vertebra](https://durgical.com/en/anatomy/t6/)

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/); [7.5 Embryonic Development of the Axial Skeleton](https://openstax.org/books/anatomy-and-physiology-2e/pages/7-5-embryonic-development-of-the-axial-skeleton) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/t5-t6-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/t5-t6-spine-and-pelvis/