It has been asserted by many researchers that children's body dimensions, proportions, and biomechanical properties are so markedly different from those of adults that a child cannot be considered simply as a scaled-down adult ( 2 , 3 , 4 , 5 , 6 and 7 ). All parts of the body do not simply grow at an even rate from birth, but develop in a sporadic and nonuniform fashion. However, such growth does not occur haphazardly, but for the most part occurs according to predictable trends.

The size and mass of the head of a child is larger in proportion to its torso than that of an adult. At birth, the child's head is one-quarter of the total body length, whereas in an adult it is one-seventh. The facial portion of the head at birth is considerably smaller than the cranium, having a face-to-cranium ratio of 1:​8 (compared to the adult ratio of 1:​2.5) ( 2 ), and the face remains tucked below a relatively massive braincase even up to the age of 6-7 years. At this age, the rudimentary maxillary sinus grows considerably, coinciding with the eruption of the second dentition. At this period, the baby face elongates and takes on more adult contours ( 8 ). The skull of the infant consists of a loosely connected system of flat bones formed from membrane matrix and cartilage. Infant and child skulls are very pliable because of this segmented arrangement of skull bones and the flexibility of the individual bones.