Armpit pain is a common complaint that can have many causes, from mild muscle injuries to swollen lymph nodes and ... rib cage and wing bone to the upper arm bone, says Lin.

This condition causes intense pain in the upper arm and a noticeable bulge ... leading to internal bleeding and swelling ...

A dull feeling in your left arm could be from overuse or strain. Learn what causes pain on this part of the arm here and ...

This muscle covers the upper arm and forms the rounded contour of ... your deltoid and shoulder for signs of injury—such as ...