What are these lines called?

Okay, I was just wondering what the little lines are called on the front of guys that point down towards their d*ck. I mean, it has to be some kind of muscle or bone or something, but how would I refer to these lines if I was talking about them in normal conversation (though I know what you guys are thinking...why would the topic even come up if the conversation was truly normal, haha) But anyway...can anyone tell me what they are? I added little arrows that point to them on a picture of Ryan Reynolds if that helps you to know what I'm talking about. So come on guys, help me out by looking at a picture of a half-naked Ryan Reynolds...you know you want to. :)