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Topography of the fasciae and cellular spaces of the breast
Medical expert of the article
Last reviewed: 06.07.2025
On the surface of the chest walls, the following bony landmarks are defined: the jugular notch of the sternum, the clavicles to the right and left of it, the xiphoid process of the sternum below, as well as the ribs and costal arches. The jugular notch of the sternum corresponds to the lower edge of the 2nd thoracic vertebra. The lower border of the body of the sternum is at the level of the 9th thoracic vertebra. The angle of the sternum is projected onto the intervertebral disc between the 4th and 5th thoracic vertebrae. On the surface of the chest walls, the contours of the pectoralis major muscle and the deltoid-thoracic groove (in men) are defined. In women, the mammary glands are located at the level of the 3rd-6th ribs, separated by a gap. On the lateral surface of the chest, a serrated line is visible, formed by the initial teeth of the anterior serratus muscle and the external oblique muscle of the abdomen. The skin of the chest is thin; in men, there is hair in the area of the sternum and shoulder blades. Sweat and sebaceous glands are most numerous in the area of the sternum, shoulder blades, and on the lateral surfaces of the chest. Subcutaneous tissue is moderately expressed, more in women. The superficial veins, terminal branches of arteries (internal thoracic, intercostal, lateral thoracic), anterior and lateral branches of intercostal nerves pass through the tissue.
The superficial fascia, which is part of the superficial fascia of the body, is poorly developed. It participates in the formation of the capsule of the mammary gland, giving off connective tissue partitions into its depths, dividing the gland into lobes. The bundles of fascia extending from the connective tissue capsule of the mammary gland to the clavicle are called the ligament supporting the mammary gland (lig. suspensorium mammae).
The pectoral fascia (fascia pectoralis), lying beneath the superficial, has two sheets (plates) - superficial and deep, which form the sheath of the pectoralis major muscle.
The superficial plate of the pectoral fascia is attached to the clavicle at the top, and medially it fuses with the periosteum of the anterior surface of the sternum. This plate continues laterally into the deltoid fascia, which passes downwards into the axillary fascia.
The deep plate of the pectoral fascia is located on the posterior surface of the pectoralis major muscle, between it and the pectoralis minor muscle. It forms the sheath of the pectoralis minor muscle. Above, within the clavipectoral triangle (between the upper edge of the pectoralis minor muscle and the clavicle), the deep plate thickens and acquires the name clavipectoral fascia (fascia clavipectoralis). Laterally and downwards from the pectoralis minor muscle, the deep plate of the pectoral fascia fuses with the superficial plate of this fascia. Three triangles are distinguished behind the pectoralis minor and pectoralis major muscles. The clavipectoral triangle is located between the clavicle at the top and the upper edge of the pectoralis minor muscle at the bottom. This triangle corresponds to the location of the clavipectoral fascia. The pectoral triangle corresponds to the outlines of the pectoralis minor muscle. The infrapectoral triangle is located between the lower edges of the pectoralis minor and pectoralis major muscles. In the area of the sternum, the pectoral fascia fuses with the periosteum of the sternum and forms a dense connective tissue plate - the anterior membrane of the sternum.
Between both pectoral muscles, lying in fascial sheaths, there is a submammary cellular space. Under the pectoralis minor muscle is a deep submammary space. Both are filled with a thin layer of fatty tissue.
In addition to the fasciae mentioned, there are also the thoracic fasciae proper and the endothoracic fasciae. The thoracic fascia proper (fascia thoracica) covers the external intercostal muscles and the ribs from the outside, fusing with their periosteum. The endothoracic fascia (fascia endothoracica) lines the thoracic cavity from the inside, i.e. it is adjacent from the inside to the internal intercostal muscles, the transverse muscle of the chest and the internal surfaces of the ribs.