Does Dijkstra's Algorithm actually check nodes marked as visited? I guess this is an implementation question, but I suppose it can be answered for the typical way this algorithm works.

So, most ways the algorithm has been explained to me involve going from a source vertex to another vertex so on and so forth. Will any edges going back to the source vertex or any already visited vertex actually get looked at, or does the algorithm ignore those because they already have their shortest path set up.
It depends on the implementation, but generally those edges are considered, but the algorithm immediately notices the target node is already visited or the new distance is greater than the old one, and doesn't process the edge further.