Medical Student Medical University of SC Charleston, South Carolina, United States
Abstract Body : Cadaveric dissections have led to the incidental discovery of a multitude of structural anomalies in the thoracic wall. Among these discoveries are vascular irregularities emanating from the internal thoracic artery (ITA), commonly known as the internal mammary artery. Reported variations include alternate origins of the ITA from either the first, second or third part of the subclavian artery. Interestingly, few have reported the presence of the lateral costal artery (LCA, an aberrant derivative of the ITA). A study in 1997, examined 100 cadavers and reported the LCA in 15 (15%) of the bodies. In 2000, a study examined 103 patients with coronary artery disease (CAD), and found the LCA in 31 patients (30.1%) with 25 of 31 displayed bilateral LCA with 18 of the 25 having an equal length LCA. Thus, the prevalence of the LCA has been predicted 15-30% in the human population. In our cadaver, we report a bilateral and asymmetry LCA that extends inferior to ribs 1-4 with differing anastomoses. The right side appears to involve connections including arteries, veins or nerves that differ in presentation compared to the left. The right LCA branches from the ITA near the first rib and extends approximately 11.43 cm inferiorly with a total length of 12.16 cm. The right LCA has a maximum radius of 7.25 cm from the right ITA. Yet, the right LCA forms an anastomosis with the intercostal arteries near the fourth rib. The left LCA has a total length of 12.7cm and descends 11.43 cm from the branching point, coursing from the first to fourth rib before anastomosing with the intercostal arteries. Lastly, the maximum radius from the left ITA was measured to be approximately 7.62 cm. The phylogenic functionality of the LCA is difficult to describe due to the lack of research in the field, but we believe that in a cardio-vascularly sound individual the increased blood and oxygen flow to the intercostal muscles would be beneficial to respiratory efforts. This theory has limitations; however, increased perfusion without appropriate capillary density and mitochondria count may not make an effective difference. The one downside to having an LCA in persons who have not undergone a coronary artery bypass graft with an ITA, would be that the body would have just wasted resources to create it. Unfortunately, this theory is difficult to prove due to limited confirmed discoveries of the vessel.
