In cartoons a bulge in the bicep is the symbol of muscularity – and that someone has been eating their spinach. In real life though, such a bulge signals something very different – and it isn’t caused by muscles at all. “It’s the biceps tendon,” said Peter Chalmers, MD, an orthopedic surgeon with University of Utah Health. “When it tears that causes the muscle to slump leading to what’s known as the ‘Popeye sign.’”