C7–T1 nucleus !
The nucleus pulposus is the soft, gel-like centre of the C7-T1 disc at the base of the neck; it works like a water cushion that spreads the load.
Official name: C7-T1
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What it is
The soft, gel-like centre (nucleus pulposus) of the C7–T1 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 C7–T1 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 C8 root
Relations
- Behind
- Annulus fibrosus and posterior longitudinal ligament, then the cord at the cervicothoracic junction
- Lateral
- The C8 root in its foramen; further out, the stellate ganglion lies in front of the neck of the 1st rib
How to find it
From behind, just below the vertebra prominens (C7); from the front it lies deep to the lower neck, a little above the jugular notch.
Examination
- C8 root: weak finger flexion and grip, numb little finger and inner forearm, no dependable reflex
- Numbness of the inner forearm separates a C8 root lesion from ulnar nerve compression at the elbow, which spares the forearm
On imaging
MRI must include the upper thoracic spine; the level is counted from C2 downward on a sagittal image, because the shoulders also blur it on plain films.
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
- A cervical rib or band pressing on the lower brachial plexus trunk (thoracic outlet syndrome) can copy a C8 root lesion; nerve studies and imaging help tell them apart
- A posterior foraminotomy suits a lateral fragment here, because from the front the sternum and the great vessels crowd this level
Development
The nucleus comes from the notochord, while the bodies form from the adjoining halves of two sclerotomes (resegmentation). This shift explains why there are eight cervical nerves but seven cervical vertebrae.
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
Which root does a herniation of the C7–T1 nucleus affect, and what is unusual about it?
The C8 root: the only cervical root with no vertebra of the same number, since it leaves below C7.
How is the C7–T1 level confirmed on imaging?
By counting down from C2 on a sagittal MRI that includes the upper thoracic spine; the shoulders blur this level on plain films.
Why are there eight cervical nerves but only seven cervical vertebrae?
Resegmentation: each vertebral body forms from the adjoining halves of two sclerotomes, while the nucleus pulposus comes from the notochord.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- nucleus pulposus C7-T1 TA2 1686
- Official Spanish (DeCS)
- Núcleo pulposo C7-T1 DeCS D000070614
- English (TA2)
- C7-T1
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Back, Nucleus Pulposus; Anatomy, Back, Intervertebral Discs.
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Representative model, for educational purposes only.
