T3 vertebra !
T3 is the third thoracic (mid-back) vertebra; it has joints for the ribs and helps form the cage that protects the heart and lungs.
Official name: T3
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What it is
The T3 mid-back vertebra, with joints on each side for the ribs.
What it does
Holds up the trunk and, with the ribs and breastbone, forms the rib cage, which protects the heart and lungs. The ribs make this part of the spine stiff.
Key facts
- Joints with
- T2 above and T4 below (discs, facet joints); heads of ribs 3 and 4; tubercle of rib 3 (costotransverse joint)
- Landmarks
- Typical thoracic: heart-shaped body; costal demifacets above and below; transverse costal facets; long sloping spine; spine level with root of scapular spine
Relations
- In front
- Superior mediastinum: esophagus with the trachea in front and the thoracic duct on its left; the aortic arch lies in front and to the left a little lower
- Lateral
- Heads of the third and fourth ribs with the sympathetic trunk and its ganglia on them; the posterior intercostal arteries cross the side of the body
- Behind
- Trapezius, rhomboids and erector spinae; the medial border of the scapula lies laterally at rest
How to find it
With the arms relaxed by the sides, the roots of the scapular spines are felt where the bony ridges of the shoulder blades meet their medial borders; the line between them crosses the T3 spine. Raising the arms rotates the scapulae and moves this landmark.
On imaging
On a frontal chest film the upper thoracic bodies are faint behind the mediastinum. CT counts levels from T1 using the first rib, but rib anomalies are not rare, so numbering by ribs alone can be off by one.
Common problems
- Compression fractures from osteoporosis, sometimes after a minor fall or even a cough.
- A rounded upper back (kyphosis) from posture, wedge fractures or Scheuermann disease in teens.
- Scoliosis: a sideways curve with rotation, often starting in adolescence.
How it is diagnosed
X-rays for fractures and curves (scoliosis is measured with the Cobb angle). MRI tells new fractures from old ones. A bone density scan (DEXA) checks for osteoporosis.
Treatment
- Osteoporosis fractures: pain control, a short time in a brace, and treatment of the osteoporosis.
- Painful fractures that do not settle: kyphoplasty or vertebroplasty (cement injected into the bone).
- Large or progressive curves: bracing in growing children, sometimes fusion surgery.
Clinical notes
- Thoracic root pain wraps round the chest in a band along the intercostal nerve and can be mistaken for heart, lung or abdominal disease
- Herpes zoster most often affects thoracic dermatomes, with a one-sided band rash that stops at the midline
- Upper thoracic disc or tumor compression of the cord gives spastic legs with a sensory level on the trunk, sparing the arms
- Sudden tearing pain between the shoulder blades is not always spinal: dissection of the descending thoracic aorta, which runs on the left side of these bodies, classically presents this way
Development
Each thoracic vertebra ossifies from three primary centres, one for the centrum and one for each half of the arch. The cartilage joints between arch and centrum (neurocentral synchondroses) close in early childhood and can look like fracture lines on images of young children.
Test yourself
Think of the answer, then tap the question to see it.
Which surface line crosses the spine of the T3 vertebra?
The line joining the roots (medial ends) of the two scapular spines, with the arms by the sides.
Which ganglia near the T3 vertebra are the target of thoracoscopic sympathectomy for palmar sweating, and what is the main drawback?
The T2–T3 sympathetic ganglia on the rib heads; compensatory sweating elsewhere is the main drawback.
Which viral disease most often affects thoracic dermatomes such as T3, and how does its rash look?
Herpes zoster: a one-sided band rash along the intercostal nerve that stops at the midline.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- vertebra thoracica III TA2 1059
- Official Spanish (DeCS)
- Vértebra dorsal D3 DeCS D013904
- English (TA2)
- T3
Related
- T2–T3 disc
- T3–T4 disc
- Posterior intercostal arteries
- Anterior longitudinal ligament
- Rib-to-spine ligaments
- Dura (dural sac)
- Endplates
- Mid-back facet joints
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Back, Thoracic Vertebrae.
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Representative model, for educational purposes only.
