According to Arnold's sources, Hounshell tore his labrum while Carlisle broke his collarbone.
Recovery timetables haven't been announced yet for either injury, but a chunk of the 2013 season could be in jeopardy for both players.
Carlisle, a redshirt sophomore, has been snakebit during much of his college career. The 5-foot-10, 185-pounder was banged up for much of his freshman year at USC, then suffered a broken ankle after transferring to Notre Dame last season. Coach Brian Kelly has been laudatory of Carlisle, and it was expected that he would be a key contributor for the Irish this fall.
Hounshell, a 6-foot-4, 265-pound sophomore, has battled shoulder injuries since arriving in South Bend, one of which forced him to sit out the entire 2012 season. He played in seven games as a 2011 freshman, tallying four tackles.