If you find an injured bird, crow or not, you should call your local U.S. Wildlife Rehabilitator, Wild Animal Rescue Facility, Animal Control, Forest Ranger, Wildlife Preserve, local vet or Wildlife Protection Agency before doing anything. Ravens in particular are legally protected animals. You have a legal as well as moral reason not to handle them before getting expert advice. You should call a professional immediately. I did some research online and found some detailed information at the Raven's Aviary regarding this topic.