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Infant Bone Development

The skeleton is the framework for the entire body. Not only does it give our body a rigid structure, enabling us to stand, sit, walk and touch things, but it offers an infrastructure upon which the body s muscles and other tissues are connected. It also helps to keep our organs where they should be.

The human skeleton models on our lineup are all life size replicas of the human body. Many of the models also contain non-skeletal components like imitation muscles, tendons and ligaments. There are very few differences between adult male and female skeletons, and between different groups of humans all over the world. However, at birth our skeletons are very different.

Cartilage vs. Bones

In order to be accommodated by an average-sized birth canal, newborns  skeletons are very soft and pliable. Infant skeletons are not composed of the same rigid bones as adult skeletons. Instead, infant bones are composed of a temporary cartilage, which forms into bones over time as the body matures.

The  Soft Spot 

Infant skulls have an unclosed area at the crown of the head, commonly called the  soft spot.  This is an area of the skull where the bones have not yet grown together, resulting in a spot where the brain is unprotected by rigid materials beneath the scalp. Part of the reason for this undeveloped area in the skeleton is to allow for rapid brain growth. During fetal development, a lot of time and energy are dedicated to brain development, while features of the rest of the body don t develop until much later. This also explains why newborn babies  heads are disproportionately large compared to their bodies.

Calcium and Bone Development

Newborn babies have around 300  bones,  many of which fuse together as the body matures. Babies require a constant supply of calcium in order for the skeleton to develop properly. This is one reason that breast milk is essential to human infants (and other animals). The calcium in breast milk is leached from the mother s body, which is why nursing mothers must take in a large amount of calcium. Additionally, calcium must be constantly replenished because it is not stored in the body. Thus, a nursing mother who isn t taking in enough calcium might suffer bone loss while nursing because the production of breast milk requires a rich source of calcium, and like most animals human mothers are biologically designed to meet the needs of their infant even at their own expense.

The development of the adult skeleton takes up to two decades, so it is important for children to get enough calcium for the first several years of life.

Bone Fusion

As mentioned above, newborns have around 300 bones, while adult humans have only 206 bones. Obviously, adults have a full set of teeth that newborns lack, so while adults have 32 more bones in the mouth than newborns, in total we have many fewer bones because so many small bones join together as we grow.

Human Variation

Because the development of the adult human skeleton is such a long and complex process, a lot of variations can occur. For example, some adults never grow wisdom teeth, while other people might grow extra teeth. There is also variation in which bones fuse together during growth into adulthood. Some natural variations occur between individuals due to genetic factors. Additionally, there are a number of skeletal disorders and abnormalities that can result from irregular bone development before and after birth.

Life size skeleton models are usually designed to display a standard skeleton with no major abnormalities. Learning about a  normal  skeleton is a good place to start studying the skeletal system, and from there it is easier to understand the causes and results of abnormal skeletal development. Many of the stores selling our favorite human skeleton models also carry infant skeleton models, which can offer an informative contrast between how the skeleton looks before and after initial childhood development.