The lateral thoracic artery is a relatively small blood vessel that runs along the side of the chest wall, feeding the serratus anterior muscle, the pectoral muscles, intercostal muscles, axillary lymph nodes, and, in women, the lateral portion of the breast. Despite its modest caliber, it has outsized importance in breast surgery, reconstructive procedures, and trauma management because of its close relationship with breast tissue and its highly variable anatomy. Studies of hundreds of dissections show that this artery does not follow the textbook description as reliably as most people assume, which makes it a vessel that surgeons, radiologists, and interventional specialists need to understand on a case-by-case basis.
Where It Comes From and What It Feeds
Anatomy textbooks typically describe the lateral thoracic artery as a branch of the second part of the axillary artery, the segment that sits behind the pectoralis minor muscle. From that origin it descends along the lower border of the pectoralis minor, then courses along the lateral chest wall. Its main job is delivering blood to the serratus anterior muscle, the intercostal muscles in the area, the pectoral muscles, the axillary lymph nodes, and the overlying skin of the lateral chest.
In women, the artery takes on additional significance. It perfuses the lateral breast and serves as one of the vessels contributing to the blood supply of the nipple-areolar complex.1PubMed Central. Rare bilateral anatomical variation of the lateral thoracic artery: duplicated arteries with unique origins and pathways – Section: Introduction That role matters during breast-conserving surgery, reduction mammoplasty, and flap design, because disrupting the artery can compromise blood flow to the nipple and the lateral breast tissue.
The Textbook Description Is Often Wrong
One of the most clinically relevant things about the lateral thoracic artery is how often it departs from its “classic” origin. Large dissection studies consistently show that the neat textbook picture holds only some of the time. In one widely cited study by Loukas and colleagues, the artery arose most commonly from the thoracoacromial artery, at about 68% of the time, while only about 17% of cases showed the textbook origin from the second part of the axillary artery. It also came from the thoracodorsal artery in 5% of cases and the subscapular artery in roughly 4%. In about 3% of specimens the artery was duplicated, and in another 3% it was absent entirely.2PubMed Central. Rare bilateral anatomical variation of the lateral thoracic artery: duplicated arteries with unique origins and pathways – Section: Discussion
Other research groups have found different distributions. A study by Olinger and colleagues found the classic axillary artery origin in about 78% of cases, with the subscapular artery accounting for another 4%. Lee and colleagues recorded the second part of the axillary artery as the origin in about 60% of their specimens, the third part in nearly 10%, and the subscapular artery in over 20%.3PubMed Central. Rare bilateral anatomical variation of the lateral thoracic artery: duplicated arteries with unique origins and pathways – Section: Discussion The disagreement between these studies likely reflects genuine population-level variation, differences in how researchers classify borderline cases, and sample sizes. The practical takeaway is the same across all of them: you cannot assume you know where this artery starts just from reading a textbook.
A recent case report described an even rarer variant, a bilateral duplication in which both sides of the body had two lateral thoracic arteries each. On the right side, the duplicate artery originated from the third part of the axillary artery and coursed directly into the breast toward the nipple. On the left, the duplicate arose from the brachial artery itself, which is even more unusual. Both duplicate vessels appeared to play a major role in breast perfusion beyond what the “primary” lateral thoracic artery contributed.4PubMed Central. Rare bilateral anatomical variation of the lateral thoracic artery: duplicated arteries with unique origins and pathways – Section: Discussion Variants like these underscore why preoperative imaging and careful intraoperative identification are so important.
Its Role in Breast Blood Supply
The breast receives blood from several sources. The internal mammary artery (also called the internal thoracic artery) is the dominant supplier in most women, with perforating branches reaching the breast from behind the sternum. The lateral thoracic artery is the second most consistent contributor, followed by anterior intercostal arteries. An angiographic CT study of 132 breasts found that the internal thoracic artery contributed perforating branches to the nipple-areolar complex in about 82% of cases, while the lateral thoracic artery contributed in roughly 24%.5PubMed. The arterial supply of the nipple areola complex (NAC) and its relations: an analysis of angiographic CT imaging for breast pedicle design When the lateral thoracic artery did contribute, its branches ran superficially about 90% of the time, meaning they travel just under the skin rather than deep within the glandular tissue.
A separate imaging study of women with breast hypertrophy found that the internal mammary artery predominated in all 60 breasts examined, while the lateral thoracic artery predominated in about 35% of them.6PubMed Central. The Main Blood Supply for The Nipple-Areola Complex of Breast Hypertrophy Evaluated by Multi-Slice Computed Tomography The variation is real and matters clinically: in a third or more of women, the lateral thoracic artery is a leading source of blood to the breast, and injuring it during surgery can threaten the nipple’s viability.
This variability was demonstrated starkly in a study of 28 patients with locally advanced breast cancer who received regional chemotherapy through catheters placed in both the internal mammary artery and the lateral thoracic artery. Using patent blue dye to map perfusion, researchers found that the internal mammary artery supplied a median of 67% of the breast, while the lateral thoracic artery supplied a median of about 15%. In a third of patients, the lateral thoracic artery contributed nothing to breast perfusion at all, with a separate branch of the subclavian or axillary artery filling the gap instead.7British Journal of Surgery. Anatomical basis of intra-arterial chemotherapy for patients with locally advanced breast cancer The conclusion from that work is that breast blood supply must be mapped individually before any procedure that depends on it.
Why Surgeons Need to Find It
In axillary lymph node dissection, one of the most common procedures in breast cancer treatment, the lateral thoracic artery runs through or very near the surgical field. A technique developed for mastoscopic (endoscope-assisted) axillary dissection specifically highlights the importance of clearly identifying the artery, alongside the intercostobrachial nerve and the thoracoepigastric vein, to avoid damaging them.8Surgical Laparoscopy, Endoscopy & Percutaneous Techniques. A Standardized Surgical Technique for Mastoscopic Axillary Lymph Node Dissection Inadvertent transection can lead to bleeding that is difficult to control in the confined axillary space, and loss of the vessel may compromise blood supply to the lateral breast and the serratus anterior muscle.
Several imaging tools help surgeons locate the artery before and during surgery. Handheld vascular Doppler probes can detect the main perforator, and high-frequency ultrasound can visualize perforating branches preoperatively. Breast MRI can also reveal the artery’s origin and its connections to the chest wall perforator network. Still, the most critical step is careful intraoperative identification, especially during axillary dissection.9Journal of Plastic, Reconstructive & Aesthetic Surgery. Anatomical study of lateral chest wall perforators and its clinical applications in oncoplastic breast surgery – Section: Discussion Computed tomographic angiography offers another layer of detail, mapping the artery’s course and perforators in advance of complex reconstructions.10Siriraj Medical Journal. Surgical Anatomy of the Lateral Thoracic Artery and Its Perforators: A Computed Tomographic Angiography and Cadaveric Dissection Study
Reconstructive and Free-Flap Uses
The lateral thoracic artery has practical value as a blood supply source for muscle flaps, particularly the serratus anterior flap. In a series of 65 patients who underwent intrathoracic transposition of the serratus anterior muscle flap for infections inside the chest, the flap was mobilized using both the thoracodorsal branch and the lateral thoracic vessels in 95% of cases. The procedure was well tolerated, with the researchers concluding that the serratus anterior flap is well suited for intrathoracic work and that involving the lateral thoracic artery in its blood supply did not introduce significant complications.11European Journal of Cardio-Thoracic Surgery. Intrathoracic transposition of the serratus anterior muscle flap — personal experience with 65 consecutive patients
Beyond its role in pedicled flaps, the artery has also been used as a recipient vessel for free tissue transfer in head and neck reconstruction. In patients who have already undergone neck dissection and radiation, the usual recipient vessels in the neck may be damaged or unavailable. A case report described using the lateral thoracic artery as an alternative recipient, noting that it provided roughly 10 cm of usable length, acceptable vessel diameter of about 1.5 mm measured 6 cm above the clavicle, and adequate blood flow.12PubMed. Lateral thoracic artery as recipient vessel for head and neck free flap reconstruction in the vessel depleted neck: A case report For patients whose neck vessels have been “used up” by prior surgeries and irradiation, having the lateral thoracic artery as a backup option can make an otherwise impossible reconstruction feasible.
Collateral Pathways When Larger Arteries Are Blocked
When large arteries like the subclavian become occluded over a long segment, the body recruits smaller vessels to reroute blood around the blockage. The lateral thoracic artery participates in one such collateral pathway. In long-segment subclavian occlusions that extend beyond the origin of the vertebral artery, collateral flow can reach the arm through branches of the thyrocervical trunk and through the lateral thoracic artery via connections with intercostal arteries.13The Annals of Thoracic Surgery. Giant Congenital Intercostal Arteriovenous Malformation With Extensive Involvement of Chest Wall and Ribs: Surgical Experience This is worth knowing for radiologists and vascular specialists interpreting angiograms, because an enlarged lateral thoracic artery on imaging may signal upstream occlusion rather than a primary abnormality of the artery itself.
Pseudoaneurysms and Traumatic Injury
The lateral thoracic artery is not commonly injured in isolation, but when it is, the result can be a pseudoaneurysm: a contained pocket of blood that forms outside the damaged vessel wall. These are treacherous because they can expand silently and rupture, causing life-threatening hemorrhage.
One reported case involved a man who developed a pseudoaneurysm with an associated arteriovenous fistula of the left lateral thoracic artery after a knife stab to the chest. His only complaint was a painful, swollen left pectoralis muscle. The pseudoaneurysm was treated successfully with coil embolization guided by fluoroscopy. The authors cautioned that missed pseudoaneurysms in this location can lead to severe bleeding and recommended more aggressive use of contrast-enhanced CT imaging for soft tissue injuries after penetrating trauma.14PubMed Central. Lateral Thoracic Artery Pseudoaneurysm as a Result of Penetrating Chest Trauma
Blunt trauma can cause the same problem. A separate case described a woman who presented with a large 15-cm, violet-colored mass in the axillary and anterolateral region of the right chest after blunt trauma. The pseudoaneurysm was traced not to the axillary or subclavian arteries, as initially suspected, but to the lateral thoracic artery, where a small 0.5-cm laceration was found. Surgical repair restored perfusion and recovered the pulses in the arm.15Jornal Vascular Brasileiro. Lateral thoracic artery pseudoaneurysm due to blunt chest trauma Both cases illustrate that injuries to this relatively small vessel can produce dramatic findings that mimic problems with larger arteries, and that identifying the lateral thoracic artery as the culprit requires careful imaging rather than assumptions based on vessel size.
Vascular Malformations Involving the Lateral Thoracic Artery
Congenital vascular malformations of the chest wall can recruit the lateral thoracic artery as a feeding vessel. One case involved a teenage girl who presented with a giant arteriovenous malformation of the left lateral chest wall, measuring roughly 9.5 by 6.8 by 4 cm and extending from the second to fifth intercostal space. The malformation was supplied by multiple intercostal arteries and a lateral thoracic branch of the left axillary artery. The tortuous feeders and the risk of embolizing critical branches of the thoracic aorta made endovascular treatment impractical, so the lesion was removed surgically with reconstruction of the chest wall.16The Annals of Thoracic Surgery. Giant Congenital Intercostal Arteriovenous Malformation With Extensive Involvement of Chest Wall and Ribs: Surgical Experience
This scenario highlights the artery’s role as a bridge between the axillary circulation and the intercostal network. In normal anatomy this connection is minor, but pathologic processes like arteriovenous malformations or chronic subclavian occlusion can enlarge it dramatically. Surgeons approaching any large vascular lesion on the lateral chest wall should anticipate that the lateral thoracic artery may be involved and plan accordingly.
Regional Chemotherapy Delivery
Because the lateral thoracic artery feeds a meaningful portion of the breast in many women, it has been used as one of the catheter access routes for delivering chemotherapy directly to locally advanced breast tumors. The idea is straightforward: by infusing drugs through the arteries that supply the tumor, a higher local concentration can be achieved with a lower total body dose. The study described earlier, in which catheters were placed in both the internal mammary artery and the lateral thoracic artery, demonstrated that the two vessels together could perfuse the entire breast in most patients. But in the roughly one-third of patients where the lateral thoracic artery did not contribute to breast perfusion, a different branch had to be identified to complete coverage.17British Journal of Surgery. Anatomical basis of intra-arterial chemotherapy for patients with locally advanced breast cancer This is a niche application, but it reinforces the central theme: individual mapping of the lateral thoracic artery is essential for any procedure that depends on it.
The Artery in Other Species
The lateral thoracic artery is not unique to humans. Anatomical studies of domestic dogs have documented it branching from the axillary artery along its course through the thoracic wall, following a pattern broadly similar to the human arrangement.18PubMed. Macroanatomic investigations of the blood supply of thoracic limb of Kangal dogs The artery’s presence across mammalian species reflects its basic function of supplying the lateral chest wall musculature, a role that is conserved because the serratus anterior and its equivalents are essential for stabilizing the scapula during forelimb movement. In humans, the added task of supplying breast tissue is layered on top of that ancestral muscular role, which helps explain why the artery’s course and territory are more variable and clinically consequential in people than in most other mammals.