RIU 435 Lecture Notes - Lecture 7: Hindbrain, Meninges, Primitive Reflexes
1 Dec 2020
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Cns arises from ectoderm neural plate around 18 gestational days. Neural tube closure between 24 and 26 gestational days. End of third week: cephalic end of neural tube bends into shape of. By beginning of fifth week another bend: Cervical flexure appears between hindbrain and spinal cord. Brain originally composed of three parts now divided into five parts that persists into adult life. Spinal cord and vertebral column extend the length of the body. After first trimester, posterior portion of body grows beyond vertebral column and spinal cord; growth of spinal cord lags behind growth of vertebral column. At birth, spinal cord terminates at level of third lumbar vertebra. By adulthood, cord will end at level of second lumbar vertebra. Neural function begins at 6 weeks of gestation. Commences with primitive reflex movements at level of face and neck. By 12 weeks, sensitivity has spread across surface of body except at the back and top of the head.
