The Lions' two offensive captains are Matthew Stafford and Dominic Raiola. There's no doubt that Stafford has taken control of the offense and the team in general, quickly becoming a leader in year two of his NFL career. Then Raiola is one of the most outspoken players on the team, so it's no surprise that he is a captain.
On defense, I think everybody expected Kyle Vanden Bosch to be the captain, so it's no surprise that he is one of them. From the minute he signed he became a veteran leader for the defense. During training camp, he served as a mentor for the younger defensive players and showed them all what kind of hustle is expected, serving as not only a leader but a role model as well.
On special teams, the captain is once again Jason Hanson. No surprises there, just as there were really no surprises with the other players that were named captains of the Lions.