Why Did My Air Bags Not Deploy?

I was in a serious accident last week with my 2008 Lincoln MKX. I do not recall how the accident happened as I have a concusion but want to ask why the air bags did not deploy in my vehicle if I had severe damage to the front and back of my vehicle after hitting an 18 wheeler ?  My insurance company just put it as totalled. I was told I hit the front left fender of the 18 wheeler as it was driving down the road. This then caused my vehicle to spin numerous times which made it keep hitting the 18 wheeler. The whole front end was totalled and the back. It looked like a mini cooper by the way it was crunched in front and back. I was told that if I never hit the break that my air bags will not go off, also someone told me that I had to be doing a certain speed in order for them to work. Not one bag went off in this vehicle. Luckily I had my seatbelt on, but curious if I would have this concussion if I had the bag working properly? I am in the process of looking into another vehicle but will not buy from Ford again till I hear the reason why this had no air bag protection.   Thank you , Cheryl Turgeon