ABSTRACT
During infancy children acquire muscle strength, balance and coordination; they lose primitive reflexes and gain protective reflexes; muscle tone changes and posture improves. They become independently mobile. The examination of motor development is not simply reliant on milestones of development, but includes qualitative observations of posture, at rest and in movement; any neurological impairment; and information regarding family and birth history.
Loss of primitive reflexes by 3 months and appearance of protective reflexes (6 months onwards) (Table 7).
Typical developmental pattern
Reducing flexor tone in the limbs resulting in increased range of movements, e.g. popliteal angle (see figure, p. 48) 90° at 2 months, 100° at 5 months and 150° at 9 months (Amiel-Tison and Grenier 1986).
Improving strength, postural control and stability — in cephalo-caudal direction:
head control (3–4 months)
trunk stability — straight spine in sitting by 8 months
legs — weight bearing (6–7 months), standing (9–15 months) (Piek 2006).
Most children (80 per cent) sit independently between 7 months (mean age) and 11 months (97th centile) and walk between 13 months (mean age) and 18 months (97th centile). About 9 per cent of children do not crawl before walking and shuffle on their 46bottom, often with a family history of bottom shuffling and/or low muscle tone; they are also very late in independent sitting (12 months mean age, 15 months 97th centile) and independent walking (17 months mean age and 24 months 97th centile). There is small group of children (1 per cent) who skip crawling or shuffling altogether and go straight to independent walking, a bit before the rest of their peer group (11 months mean age and 14 months 97th centile). All these three groups have normal patterns. However, a neurological examination is recommended for those who are not walking by 18 months of age to exclude any disorder (Robson 1984).
