延髓 The Spina|Cord脊 medulla oblongata 蛛网膜 arachnoid mater 后根根丝 posterior rootlets Position. a lies in vertebral canal a continuous with medulla oblongata at level of foramen magnum o ends at the lower border of l1 口 at birth, ends at the level of l3 S1 s1The Spinal Cord 脊髓 Position:  lies in vertebral canal  continuous with medulla oblongata at level of foramen magnum  ends at the lower border of L1;  at birth , ends at the level of L3