When most lifters decide that they want to build a six pack, they turn their focus to their abs, and rightly so. After all, the rectus abdominis takes center stage when it comes to crafting a tight, ripped midsection. Even so, there are couple of muscles, forgotten by most trainees, that can make the difference between decent abs and a really stellar perfect six pack.

While your intercostal and serratus muscles are not technically part of your abs complex, they make a strong appearance any time you crunch down into an ab pose. Develop these gems, and your six pack will shine like no other.

Here is what you need to know about the intercostals and serratus to make them pop.

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Intercostals

What They Are

The intercostals are small muscles that sit between and attach to your rib muscles. Their primary purpose is to lift and separate your ribs, and also to help collapse them. In other words, intercostals help you breathe properly, so they are absolutely essential to good health. When well-developed on a lean body, the intercostals add finger-like detail to your midsection that make you look super-ripped.

How to Train Them

It can be difficult to directly target the intercostals, but  several yoga poses get at them pretty well. Any pose which requires you to fully exhale and then re-inflate your lungs, like any of the vacuum moves, will work well. Twisting ab exercises can also give your intercostal a good workout, as can overhead cable crunches in which your hands are kept above your head.

Serratus

What They Are

The serratus is another muscle that attaches to your rib cage, but in this case, it crosses your shoulder joint and also attaches to the front of your scapula. As a consequence, the serratus helps you pull your arms down from an overhead position toward your legs, especially with a frontal rotation around your shoulders. Like intercostals, the serratus adds another dimension to your midsection that contributes greatly to a ripped appearance.

How to Train Them

Any movement that involves pulling your hands from near your head (or higher) toward your lap with straight arms will target your abs, lats, and serratus. Good examples include most pullover varieties and ab rollouts, performed with either a roller or an adjustable dumbbell.

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As with abs themselves, you won’t get much from having well-developed intercostals and serratus muscles if you don’t also drop your bodyfat to 10-12%, but knowing how to these “extras” work can give you a leg up when it comes to dialing in your six pack. If you want your midsection to really pop, you can’t afford to neglect these forgotten muscles.