Double Jeopardy star Ashley Judd wrote last night on Twitter "Amazed by the incredible outpouring of care & prayers. Thanks, everyone. Keeping our heads down here & doing what's in front of us to do."
The couple separated nine months ago but the actress rushed to his side in Texas following the crash during the final lap of the IndyCar Grand Prix of Houston.
The racing driver, who has won the Indy Car Series championship four times and is a three-time Indianapolis 500 winner, crashed into the back of rival Takuma Sato. Debris flew into the grandstands, injuring 13 spectators and an official.
Mr Franchitti, from Bathgate, also tweeted last night to fans. He said: "I would also like to send my best to all the fans involved in the accident and hope that everyone is alright."
Paramedics spent several minutes extracting the Scot from the wreckage of his car and put him on a spinal board before taking him to a waiting ambulance.
The couple wed at Skibo Castle in 2001 but in January this year they announced plans to divorce but to remain friends.