Jenkins, one of 11 offensive starters returning this season, fell hard to the ground on a long incompletion that Matt Ryan appeared to underthrow.
"I just kind of missed him," Ryan said.
The ball was thrown into zone coverage as Jenkins ran a left-to-right crossing route. Neither Smith nor Ryan indicated whether Jenkins might have run the route too deep.
Jenkins arose slowly and walked gingerly to the sideline to see the trainers.
"He's the only guy we're listing on our injury report," Smith said.
The Falcons, whose preseason opener is next Friday against Kansas City, already planned no more live tackling drills over the next five days of training camp. Jacksonville is visiting Atlanta's complex in Flowery Branch for two days of practice next week.
Smith stood behind the offense throughout the scrimmage and watched as running backs Jason Snelling and Dimitri Nance each ran for short touchdowns.
Third-string quarterback John Parker Wilson stepped up in the pocket to avoid pressure and hit running back Antoine Smith for a long TD down the right side.
Receiver Harry Douglas (knee) and running back Jerious Norwood (hip) were two leading reserves held out for precautionary reasons.
The Falcons announced that a crowd of approximately 12,200 attended the free event at North Gwinnett High School.
Copyright 2010 by The Associated Press