The Basics of Human Skeleton System
ByThe spine is the central structure around which the skull, limbs and rib cage are all articulated. The skeleton is the bony structure that supports and protects the soft parts of your body. The skull encloses the brain; the rib cage shields vital internal organs; the pelvis holds the reproductive organs and intestines; the spinal column protects the spinal cord and is the central support for the whole body.
Bones are made of a mixture of soft tissue and calcium apatite, a hard, crystal-like mineral. “Tissue” is the medical term for any collection of cells with the same structure and function. The entire body is made of different tissues. Some cells specialize in making skin, others make muscle or bone.
Although the skeleton of a newborn infant is fully formed, the bones grow and strengthen as the child develops, and their consistency changes as the years pass. The bones of a child are two-thirds soft tissue and one-third mineral, making them flexible and relatively difficult to break.
A 70-year-old, by contrast, has bones that are two-thirds mineral. This composition makes them brittle and easily broken. This is why a fall or minor accident that would leave a child or teenager just shaken and: bruised might result in a broken hip or leg for an elderly person with.
Building a hone
The body continues to build and reabsorb bone throughout life, which means that you have a completely new skeleton every 20 years or so. During childhood and adolescence, more bone is built than is absorbed, and in most of adult life bone mass remains constant. But in old age the body absorbs more bone than it builds and this can lead to thinning of the bones, a condition known as osteoporosis. This can result in fractures or, in severe cases, the crumbling of bones.
A curvy structure
Although there is a tendency to think of the spinal column as straight – people commonly tell children to “sit up straight” or describe someone as “straight-backed” – this is not the case. The spinal column actually consists of four gentle curves.
Starting from the top and working downward, the 7 cervical (neck) vertebrae curve slightly forward; the 12 thoracic (chest) vertebrae, to which the ribs are attached, curve backward to make space for the chest; the 5 lumbar (lower back) vertebrae curve forward again, producing the hollow in the small of the back; and the sacrum and coccyx curve backward. This structure makes the spinal column more flexible and better able to absorb the shocks, knocks, stresses and strains inflicted on it on a daily basis.
Related posts: