I call them "nigglies". But, to be honest, I don't care about the linked list one any more.
Because memory is cheap, I always implement lists so that an empty list contains two special nodes, first and last.
When searching, I iterate from first->next to last->prev inclusively (so I'm not looking at the sentinel first/last nodes).
When I insert, I use this same limit to find the insertion point - that guarantees that I'm never inserting before first or after last, so I only ever have to use the "insert-in-the-middle" case.
When I delete, it's similar. Because you can't delete the first or last node, the deletion code only has to use the "insert-in-the-middle" case as well.
Granted, that's just me being lazy. In addition, I don't do a lot of C work any more anyway, and I have a huge code library to draw on, so my days of implementing new linked lists are long gone.