Q and A - Forward March! - Question

A.Vestibular input, the inner-ear mechanism that allows a child to sense where the body is to help balance on two feet, is needed to achieve walking, but other mechanisms are even more important, said Dr. Joseph J. Higgins, professor of pediatric neurology atNewYork-Presbyterian/Weill CornellKomansky Center for Children’s Health.“There are many reasons why children do not walk at age 3 to 4 months,” he said in an e-mail message.

“One reason is related to adult brain mass and the time it takes the nervous system to develop after conception,” Dr. Higgins added.“Walking onset in humans as compared with that in animals occurs no later than expected, given the mass of the adult human brain.”

Another reason walking is delayed is the need for the human brain to develop myelin after birth, Dr. Higgins said. Myelin, the fatty sheath that protects nerve fibers, is needed for the effective transmission of nerve impulses to the legs. As myelin develops, the child’s movements become more accurate. 

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