ABSTRACT
The classification of development of the human brain put forward in most clinical texts describes a series of sequential mechanisms occurring in utero. As well as helping to understand normal development this scheme allows many of the brain abnormalities seen in clinical practice to be explained (at least in part). The approach is useful but a number of points should be remembered:
& The described events do not occur sequentially but overlap to a considerable degree. This explains the coexistence of different types of malformation and why they are associated. It is virtually impossible to give the exact gestational age at which the abnormality was formed.
