T1–T2 disc !
The T1-T2 disc is the thin cushion between the T1 and T2 vertebrae in the mid-back; it allows the small movement the ribs permit.
Official name: T1-T2
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What it is
The cushion between T1 and T2: a tough outer ring of fibres (annulus fibrosus) around a soft centre.
What it does
Absorbs load and allows the small amount of movement the rib cage permits.
Key facts
- Where
- Between T1 and T2 bodies; thin thoracic disc; head of rib 2 joins it
- Attaches
- Annulus fibrosus anchored to the endplates and ring apophyses of T1 and T2; anterior and posterior longitudinal ligaments
- Function
- Absorbs and spreads load; herniation rare, often central onto the cord; lateral herniation may irritate the T1 root
Relations
- In front
- Longus colli, then the esophagus with the trachea in front of it; the great vessels lie further forward, and the thoracic aorta does not reach this height
- Lateral
- Head of rib 2 and its costovertebral joint; the sympathetic trunk, with the cervicothoracic (stellate) ganglion just above on the neck of rib 1; the T1 root rising over rib 1 to join the brachial plexus
- Behind
- Posterior longitudinal ligament, the epidural space and the spinal cord
How to find it
Not palpable. The next spinous process below the vertebra prominens (C7) is T1; the disc lies deep, at about the height of the T1 tip, behind the top of the chest.
Examination
- Resisted finger abduction (interossei) tests the C8–T1 myotome; isolated weakness with a same-side Horner syndrome points to the T1 root
On imaging
The shoulders hide this level on a plain lateral radiograph (a swimmer's view or CT helps); sagittal MRI shows it well, and counting down from C2 confirms the level.
Common problems
- Thoracic disc herniations are uncommon; many are found by chance on MRI and cause no symptoms.
- A large one can press on the spinal cord, or cause band-like pain around the chest.
How it is diagnosed
MRI; CT shows whether the herniation is calcified (hardened), which matters for surgery.
Treatment
- Usually physical therapy and pain medicine; surgery only if the spinal cord is pressed.
Clinical notes
- Hand-intrinsic weakness with a Horner syndrome also fits a lung apex (Pancoast) tumour or a lower brachial plexus lesion, which are ruled out before blaming the disc
- Hard to reach from the front behind the sternum and great vessels; a posterolateral route or an extended low cervical approach is used instead
- The sympathetic trunk and the stellate ganglion lie on the rib necks just beside this disc; a lateral or anterior approach can injure them and leave a Horner syndrome
Development
The annulus forms from sclerotome cells gathered around the notochord, while the notochord trapped between two developing bodies swells into the nucleus.
Test yourself
Think of the answer, then tap the question to see it.
Which root leaves at the T1–T2 disc, and how does a lateral herniation here differ from lower thoracic discs?
The T1 root; it can weaken the small muscles of the hand, while lower thoracic discs give only a band of chest pain.
Why can compression of the T1 root at the T1–T2 disc add a Horner syndrome?
The T1 root carries the sympathetic fibres for the head and eye, giving a same-side small pupil and drooping lid.
Which rib head sits on the T1–T2 disc?
The head of rib 2, with its costovertebral joint.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- discus intervertebralis T1-T2 TA2 1684
- Official Spanish (DeCS)
- Disco T1-T2 DeCS D007403
- English (TA2)
- T1-T2
- Also called
- fibrous ring · fibrocartilago intervertebralis
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Back, Intervertebral Discs; 7.5 Embryonic Development of the Axial Skeleton (OpenStax (Rice University), 2022) · adapted, CC BY 4.0.
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Representative model, for educational purposes only.
