Arnold (concussion) practiced Tuesday after clearing the concussion protocol, Kyle Meinke of MLive.com reports.
Arnold left Monday's practice to be evaluated for a concussion, so based on the timing of his return to the field it sounds like he wasn't diagnosed with a brain injury. With Emmanuel Moseley (pectoral) out indefinitely due to a pec tear, the rookie first-round pick's presence at practice is a notable boon for Detroit's secondary. He figures to start across from Carlton Davis.