epimysium /ep′imiz″ē·əm/ [Gk, epi + mys, muscle] , the outermost fibrous sheath that covers a muscle, continuous with the perimysium. It is sturdy in some areas but more delicate in others, such as those areas where the muscle moves freely under a strong sheet of fascia. The epimysium may also fuse with fascia that attaches a muscle to a bone.