Script: Between 4 and 5 weeks, the brain continues its rapid growth and divides into 5 distinct sections.
The head comprises about 1/3 of the embryo's total size.
The cerebral hemispheres appear, gradually becoming the largest parts of the brain.
Functions eventually controlled by the cerebral hemispheres include thought, learning, memory, speech, vision, hearing, voluntary movement, and problem-solving.
|All ages referenced to fertilization, not last menstrual period.|