Protecting the origin of the pectoralis major and preventing symmastia
DIVIIDING THE ORIGIN OF THE STERNO-COSTAL PART OF PECTORALIS MAJOR (PM). In Dual Plane augmentation the Pectoralis Major is divided only in the lower part as far as the inner extent of the breast crease where it arises from the aponeurosis of the external oblique abdominis and the anterior fascial layer of the rectus abdominis muscle. Tendinous adhesions only, on the rib cartilages are divided above this point. Dividing the origin of the Pectoralis Major above the inner extent of the breast crease, will detach the Pectoralis Major and allow the implant to move to the midline of the chest wall, over the anterior aspect of the sternum, creating a deformity known as symmastia. If the origin is inadvertently divided, the implant will be visible beneath the thin skin over the sternum and could merge with the breast on the other side (symmastia).