Human beings have a skeleton that is formed by bones that support our entire body.
The most essential pillar is the spine, also known as backbone. It is vertical and is formed by a series of bones called vertebrae. The cranium and face are held at the top of the spine and the sacrum and coccyx are formed at the bottom.
At the middle of the backbone, a set of arcs called ribs jut out from the sides. Along with the sine and sternum they constitute the thorax. The upper limbs (shoulders and arms) emerge from the top of the thorax and the lower limbs (hips and legs) are born from the bottom of the spine.
Structure and composition
Bones are living structures and they are protected by three layers or tissues:
– Periosteum: a thin membrane that lines the bones. It contains nerves and blood vessels.
– Osseous cortex: tiny orifices that nerves and blood vessels pass through in order to reach the spongy tissue.
– Inner part: it is made up of spongy tissue and is full of bone marrow, the place of birth of the most important blood cells.
On the inside, bones are made of cells, of which there are three different types:
– Osteoblasts: they harden the collagen obtained from cellular protein along with minerals in order to form new bones.
– Osteocytes: they transport nutrients and waste between blood and bone tissue.
– Osteoclasts: they help shape the bone, sending minerals back to the blood.
The chemical composition of bones is as follows: 25% water, 45% minerals and 30% organic matter. Its main component is calcium, which is needed to strengthen and harden bones. Another component is collagen, which grants them flexibility.
The bones of the skeleton are bound by joints, structures that are essential to the body, for they enable coordinated and dynamic movement.
