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Lesson 02 · about 7 minutes

The vertebral column and thoracic cage

Regions of the spine, the special first two vertebrae, and how ribs attach to the sternum.

Regions of the vertebral column

The model includes 7 cervical vertebrae in the neck, 12 thoracic vertebrae that carry the ribs, and 5 lumbar vertebrae in the lower back, followed by the sacrum. Intervertebral discs of fibrocartilage separate the vertebral bodies. The coccyx is not part of the source data.

Vertebrae become larger towards the lower back, where they carry more body weight.

Atlas and axis

The first cervical vertebra, the atlas, has no vertebral body. It supports the skull, and the joints between them allow nodding. The second, the axis, has an upward projection called the dens, around which the atlas and head turn from side to side.

The thoracic cage

The twelve pairs of ribs articulate with the thoracic vertebrae behind. In front, the first seven pairs (true ribs) attach to the sternum through their own costal cartilages. Ribs 8 to 10 (false ribs) attach indirectly through the cartilages above them. Ribs 11 and 12 (floating ribs) have no anterior attachment.

The sternum has three parts: the manubrium above, the body in the middle and the small xiphoid process below.

Check your understanding

1. How many lumbar vertebrae does the model show?
2. Which ribs have no anterior attachment to the sternum or costal cartilages?
3. Which vertebra has the dens?

Further reading

OpenStax Anatomy and Physiology 2e (J. Gordon Betts et al., OpenStax, 2022) is cited as further reading. Its text is licensed CC BY-NC-SA 4.0 and is not reproduced here; SomaVista's explanations are written independently.