Medial mammary branches of internal thoracic artery

The medial mammary branches of the internal thoracic artery are small perforating vessels that arise from the internal thoracic (internal mammary) artery as it descends along the posterior surface of the anterior chest wall. These branches perforate through the intercostal spaces and the pectoralis major muscle to supply the medial aspect of the breast.

Anatomical Details

• Origin: They arise from the internal thoracic artery (also known as the internal mammary artery), which itself is a branch of the first part of the subclavian artery.

• Course: The branches pass anteriorly through the upper intercostal spaces (predominantly the 2nd through 4th), piercing the intercostal muscles and the pectoralis major to reach the breast parenchyma.

• Distribution: They supply the medial and central portions of the breast, including the skin, subcutaneous tissue, and glandular tissue. They also contribute to the blood supply of the nipple-areolar complex via anastomoses with the lateral thoracic artery branches.

Clinical Significance

• Breast surgery: These branches are of particular importance in oncoplastic and reconstructive breast surgery. During mastectomy or breast-conserving surgery, awareness of these perforators helps minimize bleeding and preserve tissue perfusion.

• Flap surgery: The medial mammary perforators form the basis of the internal mammary artery perforator (IMAP) flap, used in chest wall and breast reconstruction.

• Breast augmentation: Subpectoral implant placement may disrupt these vessels, which can affect medial breast perfusion.

• Coronary artery bypass grafting (CABG): Harvesting the internal thoracic artery as a bypass conduit sacrifices these mammary branches, which is generally well tolerated due to collateral supply but may be relevant in patients who subsequently require breast reconstruction.