Definition
Fontanelles are the areas on the skull of a newborn or infant that are not covered by bone or cartilage. They consist of robust connective tissue and bridge the areas where the skull plates have not yet grown together. There are six fontanelles in total, which close at different times. As a rule, however, all fontanelles close during the first two years of life.
Anatomy
The skull of a newborn consists of several skull plates of different sizes, which are connected shortly after birth by fontanelles and sutures (“skull sutures”). Fontanelles are bounded by at least three skull plates and connect them together. They are connected to the sutures, which are not yet ossified in the newborn and are located between two skull plates.
Together, fontanelles and sutures ensure the initial deformability of the infant’s skull, which is essential during birth and later brain growth. The six fontanelles of the child’s skull are divided into the large fontanel, the small fontanel and four lateral fontanelles. The large fontanel is located at the anterior head on the skullcap and is surrounded by four skull plates (the two frontal and two parietal bones).
It is characterized by its diamond-shaped form, which it takes up by the adjacent skull plates. Usually the large fontanel closes between the 9th and 18th month of life. In rare cases, it can also close earlier or only in the 27th month of life.
The small fontanelle lies between three skull plates (between the two parietal bones and the occipital bone) at the occiput. It is triangular and much smaller than the anterior fontanel. It often closes from the sixth week of life and is usually completely closed at the end of the child’s first year of life.
At birth, the small fontanel is usually the lowest point of the child in the birth canal. This position of the head is also the best position for an uncomplicated birth. The two anterior lateral fontanelles are located on both sides between the frontal bone, the parietal bone and the large sphenoid bone wing.
They often have a rectangular shape and are the two smaller of the four lateral fontanelles. Similar to the small fontanel, they have completely disappeared within the first year of life. The two posterior lateral fontanelles are very variable in size and shape.
They lie between the temporal, parietal and occipital bone and close up to the age of 18 months. The closure of the individual fontanelles can be greatly delayed by various deficiency symptoms, such as rickets (calcium deficiency). The following articles may also be of interest to you: Skull, Head
