Why does the skull stop growing?

Bone growth: always lengthways

When do people ossify?

Already as a fetus. The process of bone formation is called ossification or ossification. It already begins in the fetal stage. The entire skeleton of the fetus develops from the embryonic connective tissue and cartilage tissue, in which special bone cells are stored. Both tissues serve as the basic supporting substance for bone formation (also called bone matrix). Bone formation continues through puberty until the skeleton is fully formed in early adulthood and has achieved maximum growth in length. The bone tissue is constantly renewed as long as we are alive. Old, worn or damaged bone tissue is constantly being replaced by new one. This process is known as bone remodeling or bone renewal.

Do bones also grow in width?

Yes. The growth in width is made possible by cells on the inside of the periosteum. The longitudinal growth of the bones, on the other hand, takes place at the epiphyses. These special growth zones are located near the ends of the bones and are made up of cartilage cells. When the ossification process is over, growth stops in both directions. The ears and nose are made of cartilage tissue, which never completely hardens into bone tissue, and therefore grow throughout our lives.

What do bones need for their growth?

A balanced mixture of protein, calcium, vitamin D and various hormones. For normal bone growth, the body primarily needs a sufficient supply of protein so that the amino acids required for the formation of collagen are available. Collagen is an important component of the embryonic base tissue and the cartilage matrix and ensures a certain elasticity in the finished bone. Calcium is used for bone strength. The organism needs vitamin D to support the absorption of calcium and phosphates from food into the blood. Finally, hormones such as growth hormone, estrogen and testosterone as well as hormones from the adrenal, thyroid and parathyroid glands stimulate bone growth. Hormones also promote the storage of calcium in the blood in the bones.

Where are the fontanelles located?

On the skull. The gaps in the bones on the skull of newborns are called fontanelles. At birth, the child's skull bones do not yet collide directly. The gaps between the bones are covered with tough, stretchable membranes. The fontanelles allow the child's skull to change shape as it is pressed through the birth canal. Due to the shape of the skull, which can still be changed, the brain, which develops rapidly in the first year of life, has more space to develop. As soon as the skull bones grow, the fontanelles disappear. They close between the ages of 18 months and two years.

How is our size determined?

Human size is genetically predetermined. Growth, i.e. the process of bone formation, continues until the end of puberty. The body proportions change due to the growth spurt in puberty. The long bones of the arms and legs grow over a longer period of time than other bones, such as skull bones. After that - around the age of 19 - skeletal growth is complete.

Do bones age too?

Yes, the thinning and weakening of the skeletal bones is one of the normal side effects of aging. Compact bones and sponge bones increase their density until they reach their maximum at around 30 years of age. At this age, the bone mass gradually begins to decrease. Women lose a larger share than men. This happens due to the decrease in the production of the hormones that control the breakdown and build-up of bones. The lack of estrogen in particular causes old bone material to be broken down more quickly than new bone material is added. The composition of the bone is normal, but the trabeculae are thinner. Aging also means that the body produces less protein and stores less collagen in the bones. The bones therefore become more brittle and break more easily.

At around 70 years of age, bone density is only a third of its maximum and continues to decrease with age. The bone fragility that occurs especially in women after menopause is called osteoporosis.

How can a person's age be estimated?

You can do that with an X-ray. Ossification and bone growth occur at a predictable rate in every human being, so the age of a child can be easily estimated from a simple x-ray examination of the carpal bones.

Why do we shrink with age?

Most people get a little smaller again as they get older. The reason for this does not lie in the fact that the bones are getting shorter, but rather in the shrinking of the intervertebral discs, which owe their dampening effect to their high water content. Over the years, however, the proportion of water in the human body decreases, so that the intervertebral discs also become thinner over time. This shortens the total length of the spine. If there is also a health problem, for example osteoporosis, the resulting poor posture can easily make those affected appear even smaller.