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# T4 vertebra

T4 is the fourth thoracic (mid-back) vertebra; it has joints for the [ribs](https://durgical.com/en/anatomy/ribs/) and helps form the cage that protects the heart and lungs.

Official name: T4

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## What it is

The T4 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](https://durgical.com/en/anatomy/region/spine/) stiff.

## Key points

- Sternal angle plane ([T4–T5 disc](https://durgical.com/en/anatomy/t4-t5/)): border between superior and inferior mediastinum, where the aortic arch begins and ends, the [trachea](https://durgical.com/en/anatomy/trachea/) divides and the azygos vein joins the [superior vena cava](https://durgical.com/en/anatomy/superior-vena-cava/)
- The left [recurrent laryngeal nerve](https://durgical.com/en/anatomy/recurrent-laryngeal-nerve/) hooks under the aortic arch at this level, so arch aneurysms and left hilar tumors can cause hoarseness
- The T4 dermatome crosses the [nipple](https://durgical.com/en/anatomy/nipple/) in men, a standard landmark for sensory levels

## Key facts

**Joints with**
T3 above and T5 below (discs, facet joints); heads of ribs 4 and 5; tubercle of rib 4 (costotransverse joint)

**Landmarks**
Typical thoracic: heart-shaped body; costal demifacets above and below; transverse costal facets; long sloping spine; sternal angle at T4–T5 disc (tracheal bifurcation)

## Relations

**In front**
[Esophagus](https://durgical.com/en/anatomy/esophagus-abdominal-part/), indented by the [aortic arch](https://durgical.com/en/anatomy/aortic-arch/); in front of it the tracheal bifurcation (carina)

**Lateral**
On the right the [azygos vein](https://durgical.com/en/anatomy/azygos-vein/) arches forward over the root of the right lung; on the left the arch of the aorta becomes the descending [thoracic aorta](https://durgical.com/en/anatomy/thoracic-aorta/)

**Behind**
[Trapezius](https://durgical.com/en/anatomy/trapezius-muscle/), [rhomboids](https://durgical.com/en/anatomy/rhomboid-major-muscle/) and erector spinae over long, downward-sloping spines

**Contents**
[Spinal cord](https://durgical.com/en/anatomy/spinal-cord/) in the narrowest part of the canal (about T4–T9), with little room around it

## How to find it

In front, the sternal angle (angle of Louis) is felt as a ridge where the [manubrium](https://durgical.com/en/anatomy/manubrium-of-sternum/) meets the body of the [sternum](https://durgical.com/en/anatomy/sternum/), with the second [costal cartilages](https://durgical.com/en/anatomy/costal-cartilage/) beside it; the horizontal plane through it meets the back at the T4–T5 disc. Behind, the T4 spine lies a little below the line joining the roots of the scapular spines.

## On imaging

On a [chest](https://durgical.com/en/anatomy/region/chest/) X-ray the aortic knob and the carina project near T4–T5. On an AP spine film a missing pedicle ('winking owl' sign) is a classic sign of metastatic destruction.

## 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

- The thoracic spine is the commonest site of spinal metastases (breast, lung, [prostate](https://durgical.com/en/anatomy/prostate/), [kidney](https://durgical.com/en/anatomy/kidney/), myeloma); the pedicle and back of the body are often hit first
- Herpes zoster or a thoracic root lesion at T4 gives a band of pain or rash around the chest at nipple level
- A widened angle of the carina on a chest X-ray can point to an enlarged [left atrium](https://durgical.com/en/anatomy/left-atrium/) or to enlarged nodes beneath the carina
- Pedicles are narrowest in the upper and mid thoracic spine (about T4–T6), so pedicle screws here are planned on CT and a screw that breaches medially reaches the cord

## Memory aid

Sternal angle plane, 'RATPLANT': Rib 2, Aortic arch ends, Trachea divides, [Pulmonary trunk](https://durgical.com/en/anatomy/pulmonary-trunk/) divides, [Ligamentum arteriosum](https://durgical.com/en/anatomy/ligamentum-arteriosum/), Azygos joins SVC, Nerve (left recurrent laryngeal) hooks, [Thoracic duct](https://durgical.com/en/anatomy/thoracic-duct/) crosses.

## Test yourself

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

## Which plane meets the back at the T4–T5 disc, and which mediastinal parts does it separate?

The sternal angle plane (angle of Louis); it separates the superior from the inferior mediastinum.

## Why can an aneurysm of the aortic arch at the T4 vertebra level cause hoarseness?

The left recurrent laryngeal nerve hooks under the aortic arch at this level.

## What does the «winking owl» sign on an AP film of the thoracic spine, such as at T4, indicate?

A missing pedicle, a classic sign of metastatic destruction; the thoracic spine is the commonest site of spinal metastases.

## Which dermatome crosses the nipple in men?

T4, a standard landmark for sensory levels.

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

## Its names

**Official Latin (TA2)**
vertebra thoracica IV TA2 1059

**Official Spanish (DeCS)**
Vértebra dorsal D4 DeCS D013904

**English (TA2)**
T4

## Related

- [T3–T4 disc](https://durgical.com/en/anatomy/t3-t4/)
- [T4–T5 disc](https://durgical.com/en/anatomy/t4-t5/)
- [Posterior intercostal arteries](https://durgical.com/en/anatomy/posterior-intercostal-arteries/)
- [Anterior longitudinal ligament](https://durgical.com/en/anatomy/anterior-longitudinal-ligament/)
- [Rib-to-spine ligaments](https://durgical.com/en/anatomy/radiate-ligament-of-head-of-rib/)
- [Endplates](https://durgical.com/en/anatomy/vertebral-endplates/)
- [Mid-back facet joints](https://durgical.com/en/anatomy/zygapophysial-joints-spine-and-pelvis-facet-joints-thoracic/)
- [Ligamentum flavum](https://durgical.com/en/anatomy/ligamenta-flava/)

Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=14291&filter=ths_termall&q=V%C3%A9rtebras%20Tor%C3%A1cicas); [Anatomy, Back, Thoracic Vertebrae](https://www.ncbi.nlm.nih.gov/books/NBK459153/).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/t4/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/t4/