The Tigers' closer Joe Nathan said it felt like his arm was broken. That was after a rehab session with the Toledo Mud Hens was cut short yesterday after he heard a popping sound in his pitching arm after throwing 10 pitches.    The Tigers said today that Nathan underwent an MRI at the DMC yesterday which revealed a UCL tear and a flexor pronator tear. He will undergo season-ending surgery at a later date.

Nathan told reporters that even though he had never had a broken arm, he could only guess that the pain was similar to what he felt after yesterday's setback.

The 40 year old pitcher has been on the 15-day disabled list since April 7 with a right elbow flexor strain.  After throwing a bullpen session Monday, Nathan thought that he would need only one rehab appearance in the minor leagues before returning to the Tigers.  He missed the entire 2010 season after undergoing Tommy John surgery.

Nathan has a career 2.89 ERA with 377 saves, ranking seventh all-time.

At this stage of his 15-year career, it could be the end of the line for Joe Nathan. 

Joakim Soria is 5-for-5 in save opportunities since Nathan has been on the disabled list.

Nathan, 40,