The bodily proportions of a child change with the advance in age. An estimation of this change provides a measure of maturity. It is well known that different parts of the human body grow at different rates and the sequence of their reaching adult size also differs from one segment to another. One way in which the organization of growth shows itself is through the presence of maturity gradients. To explain it let us take the example of foot length, calf length and thigh length in boys. When we plot the percentage of the adult value at each age for foot length, calf length and thigh length, we find that the foot is nearer its adult status than calf, and the calf is nearer than the thigh. Thus, our foot gets matured fastest, followed by calf and thigh is the last in the sequence to achieve adult value. A maturity gradient is said to exist in the leg, running from advanced maturity distally to delayed maturity proximally. Similar gradient occurs in the upper limb, where hand achieves its maturity status earlier than forearm, which in turn, acquires maturity earlier than upper arm. Moreover, girls are more advanced in maturity at all ages than boys but the sequence of maturity in them remains the same i.e. the-distal proximal gradient.
| What are different types of growth gradients observed in different segments of our body? |
Many other gradients exist, some covering small areas only and operating for short periods, others covering whole systems and operating throughout the whole of growth. The head, for example, is at all ages in advance of the trunk, and the trunk in advance of the limbs. This type of gradient is called cephalo-caudal gradient. From early foetal life onwards the brain, in terms of its gross weight is nearer to its adult value than any other organ of the body, except the eye. At birth it is about 25 per cent of its adult weight, at 6 months nearly 50 per cent, at two and a half years about 75 per cent, at 5 years 90 per cent and at 10 years 95 per cent. This contrasts with the weight of the whole body, which at birth is about 5 per cent of the young adult weight and at 10 years about 50 per cent. Growth gradients are easy to compute. Percentage of the adult value can be easily calculated for each age group under study and plotted in a graph against each age group.