There’s one more important structure to include while we’re looking at the thorax, the breast. The female breast varies greatly in size, and also in shape. From above down the breast extends from about the level of the second rib, to the sixth rib. From side to side, it extends from the edge of the sternum, to about the mid-axillary line. This prolongation of the breast behind is called the axillary tail.
This pigmented area is the areola. It surrounds the nipple, which is the point at which the lactiferous ducts emerge.
To see the internal structure of the breast, we’ll remove one half of it, along this line. The breast consists largely of fat. This is the breast of a post-menopausal individual, in whom the glandular breast tissue has shrunk to a rather small proportion of the whole breast. The breast lies directly in front of the fascia that covers the pectoralis major muscle.
Beneath the areola, the lactiferous ducts - here’s one of them - converge on their separate openings on the nipple.
That brings us to the end of this section on the musculo-skeletal system of the thorax. In the next section, we’ll look in a similar way at the abdomen.