Q. A patient presents to neurology clinic with lumbar pain. He has radiating pain down his pain down his back into his buttock and down his lower extremity to his great toe. You plan to send him for imaging to confirm your suspicion but you tell him you believe he has an L5 radiculopathy. He asks about the cause of the radiculopathy and you explain that it is secondary to a "ruptured disc". He wants to know what the "disc" is made of and you explain that it is an embryological remnant and a discussion of neuroembrology ensues. As part of the discussion, you are asked, "what is the function of the notochord?"