Pachall has missed the last three days of practice because of the injury, and an MRI was done as a precaution.
"We don't think it's a big deal," Patterson told the newspaper.
Experience is thin at quarterback for TCU this season as the Horned Frogs replace Andy Dalton. Pachall begins the season as the starter.
Behind him, TCU has redshirt freshman Matt Brown or true freshman Trevone Boykin. Brown is believed to have a slight edge in the competition to be the backup.
Although Pachall has never started a game, he has had spot duty behind Dalton and is the most experienced quarterback on the roster.
Andrea Adelson is a national college football blogger for ESPN.com.