Sunderland send out two
McGill was deemed surplus to requirement at the Stadium of Light, and The Cumbrians stepped in to offer a three-year deal.
McGill has moved on a free transfer, although The Black Cats have inserted a sell-on clause in his contract.
Winger Ramsden, meanwhile, has inked a 12-month loan deal and moves to Meadow Lane with a view to gaining first-team action.
The 20-year-old will go straight into the squad for the weekend clash with Stockport, and manager Billy Dearden (pictured) feels it is a major boost to have the youngster with them.
Speaking to the club`s website, he said: "I'm very pleased that Simon has joined us, and it's an added boost that it's a long term loan.
"Simon will be a great asset to the club, and has always maintained his enthusiasm to join us here at Meadow Lane. He has a great attitude, and just wants to play in as many games as he can.
"It's a great addition to our squad, and his inclusion adds a new dimension to our game. Simon is a good player; he's great going forward, and I'm delighted to have him here."
Carlisle`s capture of McGill has resulted in the club releasing Ryan Hevicon and deciding not to offer a deal to Jon Cullen.