Neanderthal skulls also show evidence of a large hypoglossal canal. 尼安得特人頭蓋骨也證明了存在大量的舌下神經(jīng)管。
These are not derived from the neural crest, instead an outpouching of the neural tube generates the optic cup which, in turn, forms the retina. 不過(guò)視網(wǎng)膜上皮的黑色素細胞是其中的例外，它們并非由神經(jīng)脊產(chǎn)生，而是在神經(jīng)管外囊生成的視杯產(chǎn)生。
Because the spinal cord is encased within its bony canal, it cannot move away from the pressure and it becomes pinched. 由于脊髓受到骨質(zhì)椎管的限制，不能避開(kāi)壓迫物，而受到擠壓。
At the caudal end of the sacrum the roof of the vertebral canal is commonly deficient. 在骶管末端，椎管往往缺損。
