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Figure 5. Spine

The thoracic spine consists of 12 thoracic vertebrae, which are semi-movable
connected to 12 pairs of ribs.
The lumbar spine is formed by 5 massive lumbar vertebrae.
All 5 sacral vertebrae fuse into a single sacrum, firmly connected to the pelvic
bones. Such a powerful structure was formed in order to provide support for the body
during the transition to upright walking, and is characteristic only for humans. The final
fusion of the sacral vertebrae usually occurs by the age of 18-20. The tip of the sacrum
connects to the coccyx.
The coccygeal spine in humans is formed by 4-5 small fused vertebrae.
Due to the transition of people to walking upright, four bends were formed in the
spine, two of which are directed forward with a bulge – cervical and lumbar lordoses,
and the other two are directed backward with a bulge – thoracic and sacrococcygeal
kyphoses. Thanks to these bends, reliable cushioning of the brain is provided when
walking.

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CHEST
The thoracic vertebrae, ribs and sternum form the chest, in the cavity of which
the heart, lungs, trachea and esophagus are located. Due to the movements of the chest,

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