The pectoralis major is a thick, flat muscle covering the upper front of the chest, beneath the upper inner portion of the breast gland. The lower outer portion of the breast is on top of another deeper muscle, the serratus anterior. The pectoralis major has a broad origin from the collarbone above, the sternum (breastbone) in the middle, and the ribs below. Pectoralis muscle fibers converge upward and laterally in front of the ribs to form the front border of your armpit, then insert on the upper inner arm bone, the humerus.
Breast implants are not natural, but are synthetic mechanical devices. They do not always appear or behave 100% naturally. Deeper implant placement helps camouflage implant-related imperfections. One popular technique for deeper placement is to lift the lower part of pectoralis major muscle, develop a pocket for the implant beneath this muscle, and place the implant within the “submuscular,” or “subpectoral” pocket. This actually results in a “dual plane” position, meaning the upper inner portion of the implant is beneath pectoralis muscle, while the lower outer portion, because it extends below the lower margin of pectoralis muscle, is beneath the breast gland.
The alternative to subpectoral (“dual plane”) positioning is the “subglandular” position. This means the implant is placed in a pocket behind the breast gland, entirely on top of the pectoralis major muscle. Advantages of subglandular placement include no interference with pectoralis muscle function, no “animation,” or movement of the breasts that occurs with arm movement if the implant is subpectoral, and no requirement for stretching of muscle for the implant to settle into its final position.
Both subglandular and subpectoral implant positioning are acceptable for every type of implant, however, depending on your anatomy, lifestyle, preferences, and the particular implant you choose, one position may be preferred over the other.
Submuscular positioning is recommended for very thin, lean women with saline or cohesive silicone gel implants. Because the muscle better conceals implant characteristics, edges and rippling may be less visible. Because highly cohesive silicone gel devices do not ripple or wrinkle, submuscular placement is less important for visual camouflage, but may be preferred because of the firmness of these implants. When a breast lift is simultaneously performed, submuscular implant placement improves blood supply to the overlying breast. On the other hand, if your breasts are slightly sagging, subglandular placement offers a lift effect unrestricted by overlying muscle. Subglandular placement avoids disturbing implant “animation.” Animation is breast implant movement caused by arm movement and contraction of the pectoralis muscle. Women who compete athletically or who are very active with their upper body may want to avoid surgical manipulation of their pectoralis and dynamic breasts that are inevitabilities of sub-muscular (dual-plane) implant placement.
This space is often referred to as a “pocket” for the implant. The location and size of the pocket are important. Attention to detail during your procedure contributes to subtle aspects affecting the quality of your result. During surgery, if the bottom of the pocket is opened too widely, implant position may be too low. If the bottom of the pocket is not opened sufficiently, implant position may be too high. If the pocket is too large, the implant may displace. If the pocket is too small, edges of the implant may be visible, and the small pocket may squeeze the implant causing visible rippling or wrinkling. If the implant is submuscular and the inner edge of the pectoralis is not divided enough, animation may be excessive, and/or the implant may laterally displace (move to the side) producing a wide space between the breasts. If the pectoralis is divided too much, the lower inner edge of the implant may end up beneath skin only, resulting in visible rippling and wrinkling exactly where many women want a sexy and beautiful cleavage.
Other elements, most notably your skin elasticity and how much your skin stretches after surgery, affect breast augmentation results, but can be unpredictable and uncontrollable. In any case, because of all these variables, your surgeon must develop your breast implant pocket extremely carefully for the best outcome.