In children, a critical period for the acquisition of motor skills is preschool years (ages 3–5), as fundamental neuroanatomic structure shows significant development, elaboration, and myelination over the course of this period. Many factors contribute to the rate that children develop their motor skills. Unless afflicted with a severe disability, children are expected to develop a wide range of basic movement abilities and motor skills. Motor development progresses in seven stages throughout an individual's life: reflexive, rudimentary, fundamental, sports skill, growth and refinement, peak performance, and regression. Development is age-related but is not age dependent. In regard to age, it is seen that typical developments are expected to attain gross motor skills used for postural control and vertical mobility by 5 years of age.