The neural plate then forms the neural tube as well as these tiny neural crests. And the neural crests give rise to the peripheral nervous system while the neural tube gives rise to the central nervous system the brain as well as the spinal cord. So we see that the nervous system begins to form during the first trimester. Now, we also have many other organs begin to form. For example, we begin the formation of the heart and we begin the formation of the lungs. We also begin to form our digestive system.