Breast Anatomy

Breasts are paired structures present in both males and females, though they are larger in females after puberty. Here we see the breast from the sagittal aspect. It lies superficially to the pectoralis major and serratus anterior muscles on the anterior thoracic wall. Horizontally, each breast covers the region from the sternum’s lateral border to the mid-axillary line.

Vertically, the breasts run from the 2nd to 6th costal cartilages. Each breast has two regions: the circular body, which makes up the bulk of the breast, and the axillary tail, which runs along the inferior lateral edge of the pectoralis major towards the axillary fossa.

Get 10% off Kenhub with this code! https://khub.me/neuralacademy

The nipple is the central protruding part of the breast, and it is composed primarily of smooth muscle fibers. The areola is the pigmented skin area that surrounds the nipple. It has numerous sebaceous glands which enlarge during pregnancy and secrete an oily substance to lubricate the nipple.

Breasts have mammary glands. These modified sweat glands are involved in lactation, or the production of milk. These glands consist of sections called lobes, and there are about 15-20 of these per breast, arranged in a circle like the petals of a flower. Each lobe consists of many smaller lobules, which are glands that produce milk. Lobules are composed of numerous tiny, hollow sacs, called alveoli, which drain into a single lactiferous duct. Lactiferous ducts converge at the nipple. Just before these ducts enter the nipple, they are dilated at the lactiferous sinus. Production and secretion of milk is regulated by the hormones prolactin and oxytocin, which are secreted by the pituitary gland.

The mammary glands are surrounded and supported by a connective tissue stroma. This tissue has fibrous and fatty components. The fibrous stroma forms Cooper’s ligaments, also known as the suspensory ligaments of Cooper. These ligaments maintain the shape of the breast, separate the secretory lobules and secure the breast to the skin and the underlying pectoral fascia. The pectoral fascia is a sheet of connective tissue associated with pectoralis major.

The retromammary space is a layer of loose connective tissue between the breast’s base and the pectoral fascia. This space is often exploited during reconstructive plastic surgery.