The human skull is not only the most important bone formation, but also the most visually noticeable. Therefore, all its changes cannot go unnoticed. The staging of such transformations is relatively relative and individual for each person, but there are general principles depending on age.
Throughout life, the human skull undergoes many changes. This primarily relates to its appearance. Five large periods of such transformations are conventionally distinguished. Let's consider each of them in more detail.
First period
This period is the most active stage of head growth and lasts for the first seven years of a person’s life. From the moment of birth to six months, the volume of the brain region of the skull almost doubles. By the age of two, its volume tripled, and by the age of five it is three fourth of the volume of the entire skull. This ratio lasts a lifetime. It is during this period that the cranial fossa deepens significantly, and the occipital part of the head begins to protrude. In addition, the membranous tissue of the cranial vault and the cartilaginous tissue in the occipital bone mutate and gradually disappear. The first (initial stage) of the formation of sutures of the bone skeleton of the head occurs. This period is extremely important because the seam of the skull is not just designed to hold the bones of the head together, but, more importantly, is the place of their growth in width.
Classification of skull sutures
Seams are divided in their form into the following:
The serrated skull suture is formed by two bony surfaces when there are protrusions on one and notches filling the protrusions on the other. This type of seam is the most durable. When overlapping two edges of adjacent bones, a scaly skull suture is formed. All seams are filled with connective tissue, giving strength and mobility to such joints. And the third type of seams is flat. A flat suture of the skull is formed by the contact of slightly wavy or completely flat bone surfaces. Using this type of suture, the bones of the facial skull are connected to each other, and their name depends on the connecting bone formations.
Second period of change
Over the next five years, the bones of the head grow much more slowly. A more noticeable change in the growth and shape of the facial part of the skull (eye sockets, nasal cavity and upper jaw) occurs. The fontanelles, closed during the neonatal period, completely disappear, and the sutures are filled with connective tissue.
Third period
This period coincides with the puberty of a person and lasts for ten years (from 14-15 years of age to 25 years). The final growth of the skull and the entire axial skeleton occurs . In this period of life (in contrast to the previous two), a more intensive growth of the facial skull occurs, rather than the brain. The suture of the skull, as an anatomical formation, becomes more durable, and the period of its ossification begins, which lasts until old age. The base of the skull increases in all directions, and not just in width. Finally, furrows, protrusions, tubercles and airways sinuses are formed.
The fourth period
From 25 years to 45, no changes in the development of bones of the head occur. During this period, the seam of the skull ossifies. In very rare cases, sutures can persist throughout life.
Fifth period
This stage lasts from the period of suture healing to the very old age. To a greater extent, not anatomical changes occur, but structural ones. The facial skull visually changes due to tooth loss and atrophy of the alveolar processes. With age, the thickness of the spongy substance and compact plate decreases, and the skull becomes lighter. Due to resorption of bone tissue and changes in its mineral composition, bones become more fragile, crack and break.
Conclusion
The human skull is the so-called skeleton of the head. This anatomical structure is extremely important not only for protecting the brain and sensory organs. She shapes our appearance (face).
The suture of the skull, being a structural-functional unit, plays an important role in connecting the bones of the skull to each other. In children, the seams have greater elasticity, and with age they ossify.
The stage of development of the bones of the skull has an age framework. So, the period of the newborn, when fontanelles are still preserved (membranous stage), with the person growing up, passes into the cartilaginous stage, and then into the bone.
By the time of birth, the formation of the skull itself does not end. There are five stages of its development. So, from the moment of birth to school age (6-7 years), the skull grows mainly in height, the next five to seven years are a period of relative dormancy, and with the onset of the puberty period and up to the age of 25, mainly its face is modified.