Anatomy of Carrying
Adaptation to carrying can be perfectly seen in an infant’s body structure. In order to understand thoroughly what physiology of babycarring in slings and soft carriers consist in, it is necessary to examine the baby’s anatomy in the first year of life. Infancy is a very peculiar period because
then the dynamic development of motor and sensory centers in the central nervous system takes place. Some of the basic phenomena of this period are: spinal curvatures forming, movements development, and changing body position into more vertical.
Spine Development
The development and the correct forming of a baby’s spine is a complex process which lasts until a child becomes a teenager. Its initial stage begins in the baby’s first year of life and it consists in straightening or correct forming of the physiological curvatures: cervical lordosis, thoracic kyphosis, lumbar lordosis.
The spine of a newborn baby is in a stage of the complete kyphosis. It is a physiological curve
resulting from a fetal position. The process of spinal straightening is evenly spread over time and adjusted to the natural developmental rhythm of a baby. Even if a baby can sit with the back straight or stand straight for a few minutes, during sleep the muscles relax and the back returns to its curved shape. If we carry a sleeping baby we must remember that the back and head should be supported in such a way that won’t force an unnatural position of a baby’s body.
The first of the formed curvatures is cervical lordosis. The process of straightening of this part of spine begins between 4-8 week of life. At that time, a baby lying on the front begins to lift the head for about 3 seconds. During the next three months, 7 cervical vertebrae go forward and upward. This process is finished when a baby can hold the head by him/herself (about 4 months old.) Thoracic kyphosis is formed as a second curvature. During this process, the next 12 vertebrae go backward and upward. This stage of spinal straightening falls on the time when a baby is learning how to sit. The span of this period is very individual; however, usually a 10 months old baby is able to sit with the back straight unaided.
Lumbar lordosis is the last stage of spinal straightening. 6 lumbar vertebrae straighten- they go forward and upward. This process is finished when a baby can stand up and takes the first steps. The spine is completely straightened, that is it takes on a typical for a human being S-shaped form, when a baby can walk unaided.
Development of Hip Joints
The acetabulum of the hip join consists of three bones: ilium, sciatic and pubic. Simultaneously, they make up the pelvic bone. The components of the acetabulum are joined by the Ypsilon cartilage (Y-shaped.) In newborn babies, the process of ossifying is not finished yet, so the shape of the acetabulum is quite different than in adults. The most important factors which have an influence on the correct development of the acetabulum are the processes of ossifying of the adjoining pelvic bones and the development of the cartilage. The latest research shows that none of the processes will proceed correctly unless the head of the thighbone is put properly into the acetabulum. Nature has equipped newborn babies with such an ability of placing the legs which ensures optimal filling of the acetabulum. When a newborn baby is taken in the adult’s arms, he/she pulls up the legs spreading them simultaneously and taking on a froglike position. It enables to put a baby on a parent’s body in such a way that the heads of the thighbones were pushed into the acetabulums. It gives the impressions that a baby is born to be carried, and babycarrying is a natural response to baby’s needs.
In this position, the tendons which are between the head of the thighbone and the acetabulum stay relaxed, and all the elements of the head of the thighbone and the acetabulum are loaded evenly.
When we analyze the position of the baby’s legs, we can observe that it is 100-110° flexion (angle between the ankle bone and the thigh) and about 50° spreading (angle between thigh and the hip joint.) Exactly the same parameters are applied by the orthopedists who treat hip dysplasia by using the Pavlik harness.
The next essential element is the pelvic girdle which is a link connecting the lower limbs with the lumbar region of the spine. It consists of the pelvis and sacrum. All of these elements constitute one integral whole and their movements are mutually determined. That is the source of the mutual dependence of a froglike position of the ideally curved infant’s back. If we straighten a baby’s back by force, the correct position of the legs is impossible. If the legs aren’t placed correctly, the baby’s spine suffers.
A baby who is well tied in a sling, takes on a physiological froglike position; a baby wrap sling
stabilizes this system thanks to what a sleeping baby is absolutely safe. The spine of a baby carried in this way isn’t loaded, and the heads of the thighbones properly fill the acetabulum determining at the same time the regular development of the hip joints. Consequently, it is worth taking into consideration how and in what we carry our babies. Strong children are able to hold a proper position for some time; however, when they fall asleep they lose control over it. As parents, we should make every effort to benefit from the potential given us by evolution.
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