INTRODUCTION

In infants and young children at risk for motor disturbances, clinicians are interested in the temporal occurrence and pathways of motor behaviours, the quality of motor performance as an expression of neurological integrity, and adverse events which may affect motor development. The following questions are of particular clinical importance:

• Is there one pathway or are there different pathways of early motor development in normal children?

• Is motor development dependent on conceptional or chronological age? Has age to be corrected for prematurity in order for an accurate judgement of motor development to be made?

• How does cerebral damage effect the age-related course and pathways of motor development?

• How do neurological functions (e.g. tendon reflexes, muscle tone) relate to age-dependent measures of motor development (e.g. onset of walking)? Does this relationship change over age?

• To what extent is motor development influenced by prenatal, perinatal and postnatal factors?

• Is the onset and sequencing in motor development stable over generations?

Most of these clinically relevant aspects of early motor development can be analysed only in a longitudinal manner (Wohlwill, 1973). The aim of this chapter is to address these questions on the basis of the data of the Zurich longitudinal studies.