Open Question: How do I get the cut between the bi/triceps and below your shoulder blades?

Anybody have exercises to get that more cut line that goes around your arm that connects your shoulder blade/cap and your bi/triceps http://media.photobucket.com/image/buff%20arms/penguin_furuba/People/jamie_bamber400.jpg see that line connecting his shoulder and biceps on his left arm....whats that called? and any exercises to get a more defined cut?