Air bags are designed to deploy only under certain conditions, usually in the event of a . Multiple car collision
Fairly severe frontal collision
Rear end collision
Fender bender

between the two muscle layers is the myenteric or auerbach's plexus, which controls peristalsis. in the colon, the muscularis externa is much thicker because the feces are large and heavy, requiring more force to push along. the stomach has a third layer of muscularis externa: the inner oblique layer.