10.3. Breast: Blood Vessels, Nerves and Lymphatic Drainage
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The blood supply to the breast arises from three sources: branches of the axillary artery, branches directly from the internal thoracic artery and branches from the anterior intercostal arteries (mainly at the levels of the second to sixth ribs). See the diagram to visualise this.
Some of the very anterior veins draining the breast form an anastomotic circle around the base of the nipple. This is called the 'circulus venous'. Other veins also exist throughout the breast. All of these veins drain their venous blood into one of two locations: the axillary vein and the internal thoracic vein.
The sensory nerves supplying the breast are derived from the anterior and lateral cutaneous branches of the intercostal nerves (normally the fourth, fifth and sixth intercostal nerves). Sensory fibres are conveyed here, as are some sympathetic fibres. However, most secretory activity of the breast is regulated by hormones.
The lymph vessels of the mammary gland originate in two areas: a large lymphatic plexus lying in the connective and adipose tissue between the lobules, as well as a cutaneous (skin) plexus lying just underneath the areola. More than 75% of the lymph from the breast is received from these plexuses into the axillary group of nodes in the superolateral quadrant of the breast. These are shown in the diagram. This axillary group of nodes is made up of:
- Anterior axillary group
- Central group
- Apical group