劍橋詞典a substance containing a lot of fat that forms a covering around nerves , especially those in the brain , protecting them and helping them to send signals effectively 髓磷脂（含大量脂肪，特別是在腦神經(jīng)周圍形成保護層，保障腦神經(jīng)有效發(fā)出信號） The myelin sheath around the neuron is damaged . 神經(jīng)元周圍的髓鞘遭到破壞。 返回 myelin