A common question amongst bodybuilders regarding arm training is which exercises target the lateral triceps region
the most effectively? Basically, any exercise that extends your elbow will work all three heads of your triceps;
this is basic anatomy. While you simply can't isolate one part of any muscle over another with different exercises,
the triceps is somewhat unique in that it has three distinct heads. Not only that, but the long head's attachments
are such that this part of your triceps is recruited slightly more than the lateral and medial heads in movements
where your elbows are over your head. Examples are the overhead triceps extension and the French press, if you allow
the dumbbells, barbell or EZ-bar to extend beyond your head. Conversely, any exercise that keeps your upper arms to
your sides - such as press downs, reverse press downs and one-arm cable press downs - or at 90 degrees to your upper
body, such as close-grip benches, will hit the medial and short heads slightly more. This means you can slightly
emphasize one area over another, but the medial and short heads are always crankin' irrespective of the exercise.
So here are more questions: Can the slightly greater amount of emphasis found in over-the-head exercises add up to significantly greater long-head growth patterns? If you skipped those exercises, would you get more development in the short and medial heads than in the long head? Frankly, I don't have the answers, but I'm skeptical. What you're basically left with is your unique development in this area; you'd be hard-pressed to change your genetics. But the good news is that this really has no bearing on your ability to grow. My recommendation is to pump some serious iron, focusing on progressively moving heavier and heavier weights.
Try hitting your tri's twice a week. Train them hard and heavy for two weeks straight, then in the third week, go hard and heavy on the first training day and easy on the second. For the fourth week, go easy on the first day and go to failure on the second. Then repeat the cycle. As you're hitting it hard, though, don't overlook proper technique. Don't let the weights dictate your movement; you dictate the movement to the weights. Make your triceps do the work! Continue to pump away and you'll notice your tri's getting stronger and bigger. With the added size, I bet you'll find that your tri's will take on a more balanced look.