Blue Jays right-hander Brandon Morrow was diagnosed with an entrapped radial nerve in his right forearm during a visit to Dr. James Andrews on Wednesday and is expected to miss about six weeks.

Morrow has been on the disabled list with soreness in the forearm since June 1 and hasn't pitched for Toronto since May 28, when he exited a start against the Braves after two innings. The 28-year-old last saw game action on June 17, a rehab start for Class A Dunedin. He was then shut down with the same problem.

Morrow had begun throwing side sessions again, but with the forearm continuing to cause trouble, he went to see Dr. Andrews. Once the soreness subsides, he will begin a throwing program.

Morrow also has battled upper back and neck tightness this season while making only 10 starts and going 2-3 with a 5.63 ERA. He has spent time on the DL during all four of his seasons with the Blue Jays, during which he has gone 33-28 with a 4.32 ERA.