Anne Heche's Cause of Death Revealed, Smoke Inhalation & Burn Injuries

Anne Heche died from smoke inhalation and thermal injuries ... which she obviously sustained when her car went flying through the home of a woman in Mar Vista a couple weeks ago ... this according to the L.A. County Coroner.

The Coroner notes another significant factor that contributed to her death was a sternal fracture due to blunt trauma. That essentially means part of her chest was crushed in the accident ... which left her in a coma for the remainder of her life.

Anne's death has been listed as accidental.

As we reported ... Anne was declared brain dead last week, which is considered legally dead in California. Her body was kept on life support for a little while longer so doctors could properly harvest her organs and find donors, which they ultimately did.

The day of the car crash was well documented by bystanders and security footage -- much of which showed Anne flying through the residential area at incredibly high speeds and nearly hitting people along the way. She struck a garage and car before plowing into a house.

While being carried by stretcher into an ambulance, she briefly came but then lost consciousness.