There are two main placement options with breast implants: over or under the chest muscle.
If you're choosing to have your breast implants placed under the chest muscle (pectoralis major) you may have heard of something called dual plane placement.
Dual Plane Breast Implant Placement
Despite sounding like it, this has nothing to do with aeronautics! Instead, it's all about where under the muscle your breast implants are placed.
When you think of a breast implant under the muscle you wouldn't be alone if you imagined that it was placed completely under the muscle.
There aren't many plastic surgeons though who will place implants fully under the muscle. Instead, most implants in the 'under' placement are only partially under the muscle.
Breast implants are partially under the muscle because the top part is under the pectoral muscle and the bottom part is under the breast tissue.
So, really, when we say submuscular when we're referring to unders it's not actually technically correct! We should be saying subpectoral, because unders are only partially under the pectoral muscle... not the whole chest muscle.
With dual plane, your plastic surgeon tailors the placement of your implants with varying degrees of muscle release/separation from the breast tissue in order to vary the amount of muscle/breast tissue coverage.
Choosing Dual Placement for your breast implants
Depending on which order you make the key breast implant decisions (location, incision, type, size, shape) it's worth knowing that breast implants in the dual plane location can only be placed via a nipple (areolar) or underboob (inframammary fold/crease) incision.
Dual plane placement works well if you have slightly droopy breasts because the surgical technique involved can give the illusion of a little lift to the breasts.
To fully understand what dual plane means you'd have to understand a bit about the muscle anatomy of the chest wall. If the thought of anatomy 101 gives you the shivers and your plastic surgeon is recommending the placement of your implants 'under the muscle' just ask them to tell you how much under the muscle.
Basically, dual plane is a form of under the muscle or, more accurately, subpectoral placement.
The bottom line with any breast augmentation is that you need to go to a Board Certified plastic surgeon who does excellent work.
Whatever placement option they recommend should come with a full explanation of the benefits, so you can make an informed decision! :-)