My wife just sent me an email with a file called "ANUS.doc" attached. It wasn't quite as hilarious as I was expecting:
The dentate line- location of anal crypts and draining of glands
Superiorly visceral afferents, therefore non-painful; columnar epithelium
Inferiorly somatic afferents, therefore painful; stratified squamous epithelium
Doctors have to talk about funny things like anal crypts and gland drainage, but they have to be all clinical about it. It's sort of a shame.