Lateral Thoracic Artery Branches (Breast)

The lateral thoracic artery provides a major blood supply to the lateral aspect of the breast, particularly the axillary tail and overlying skin. It is a direct branch of the axillary artery and plays a vital role in the vascularization of the breast, especially in women of reproductive age. The artery also supplies nearby muscles and lymph nodes, and its branches are essential in both physiological processes and surgical procedures involving the breast and axilla.

Origin of the Lateral Thoracic Artery

The lateral thoracic artery arises from the second part of the axillary artery, usually just distal to the origin of the thoracoacromial artery. Its course is variable, but in most individuals, it descends along the lateral border of the pectoralis minor muscle and travels toward the lateral thoracic wall.

Course and Distribution

After originating from the axillary artery, the lateral thoracic artery travels inferomedially along the lateral thoracic wall. It gives off multiple muscular, cutaneous, and glandular branches along its path. It typically runs parallel to the lateral edge of the pectoralis major and minor muscles and may be accompanied by the long thoracic nerve and vein.

Branches Supplying the Breast

• Cutaneous branches: Supply the skin overlying the lateral breast and axillary region
• Glandular branches: Enter the lateral aspect of the breast parenchyma and supply the mammary lobules, particularly in the upper outer quadrant
• Anastomotic branches: Form vascular connections with perforators of the internal thoracic artery, thoracoacromial artery (pectoral branch), and posterior intercostal arteries

In many women, the glandular branches of the lateral thoracic artery are more prominent during puberty, pregnancy, and lactation due to increased vascular demands of the breast tissue.

Territory of Supply

The lateral thoracic artery primarily supplies:

• Lateral half of the breast, including the axillary tail (of Spence)
• Lateral thoracic wall, including intercostal muscles and overlying skin
• Axillary lymph nodes and surrounding connective tissue
• Serratus anterior and pectoral muscles (to a lesser degree)

Functional and Surgical Significance

• Breastfeeding: Blood flow through the lateral thoracic artery increases during lactation, supporting milk production and ductal expansion in the lateral breast
• Breast surgery: This artery must be preserved or managed during axillary clearance, tumor resection, or lateral flap reconstructions
• Lateral thoracic perforator flaps: Used in oncoplastic breast-conserving surgery or reconstruction; these rely on the perforating vessels branching from this artery

Clinical Considerations

The lateral thoracic artery can be a source of intraoperative bleeding during axillary surgery or breast dissection. In patients undergoing mastectomy or lymph node dissection, injury to this vessel must be avoided or carefully ligated. Enlarged or prominent lateral thoracic arteries can also be seen in hypervascular conditions such as inflammatory breast cancer or advanced lactation. Doppler imaging may be used to assess flow in this vessel during preoperative planning for reconstructive procedures.