The breast doesn't contain muscles. Breast tissue is found along with the muscles with the upper body wall. Blood vessels and lymphatic vessels (a method of vessels that drains fluid) can be found through the breast. Bodily variations to the breasts tend to be recorded in the extend marks with https://grok.com/share/c2hhcmQtMw%3D%3D_21b4ddf4-c274-418a-a078-c9d2af4898ff