On first glance this arm might appear to belong to someone who has been hitting the gym, however you might notice the bulge of the muscle is quite low down towards the elbow. This is in fact due to a ruptured biceps tendon that causes the muscle to bunch up (also known as the Popeye sign!). If the individual doesn't mind the cosmetic differences then this condition can just be left alone, alternatively the tendon can be re attached surgically.