Blood supply:

Axillary artery --> Lateral thoracic (major) + acromiothoracic branches

Internal mammary artery --> 1st and 2nd perforating branches (pierce intercostal spaces, traverse pec major; supply medial breast)

Intercostal arteries; lateral perforators (minor)

Breast blood supply and lymphatics

diagram breast blood supply

Lymphatics: Follow vessels

Axillary chain along axillary vessels

Internal mammary chain + LN near lateral perforators of intercostal arteries along internal mammary vessels

Plexus of Sappey (subareolar lymphatics) 75% axillary; 15% internal mammary, upper can go to supraclavicular chain; lower can go to abdominal nodes

diagram breast lymphatics, showing levels 1-3