Can someone help me find this old horror movie?

Today I watched The Serpent and the Rainbow, which I was kind of sure I saw before. Except I didn’t. it was a freakin’ awesome movie I really enjoyed it.
But now I’m left wondering just what the hell this other movie was, which I mistook for The Serpent and the Rainbow.

I saw it with my dad as a kid, one of his friends was a huge zombie/horror freak and he lent us this.
Here’s what I remember; right in the beginning, there’s a pathology instructor with some young students, and they’re about to perform work on a dead body. When the teacher lifts the cover from the corpse, we notice that its hand has been sawed off. The students start laughing, and the teacher says, you think this is funny? Class dismissed. Everyone leaves. There’s a part before or after that where you see some guy stick a severed hand in a suitcase, and he runs off.
After that, most of the movie takes place on a tropical island, where some cannibals live. I think they’re cannibals…They’re a crazy bunch.
There’s some mad doctor that lives there too, and he creates these super zombie monsters, and even the cannibals fear them. A shack gets firebombed by molotov cocktails. That’s all I can really remember. Wasn’t the greatest movie ever, but now I’m curious. Judging by its style, I’d say it’s from the seventies or early eighties.
Does anyone have any idea what this movie is?