User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-70.128.20.68-20130428201415/@comment-4813670-20130428203212

either through reward items, or by carving nargas' tail. Actually, any medulla can be obtained the same way on every monsters that actually have medullas (rathalos/rathian/narga...). That is to say, as I said, on tails and through quest rewards. This is supposed to be rare, so you may want to kill many narga before actually getting you first medulla.