RESUMEN
The passage of the superior epigastric artery (SEA), the terminal branch of the internal thoracic artery (ITA), through the inferior orifice of the thorax differs in different reports. According to some, it passes through Larrey's space (trigonum sternocostale), therefore through a diaphragmatic orifice, but according to others it passes in front of the diaphragm and the transverse abdominal muscle. The aim of this study was to determine the position of the SEA in its thoracoabdominal segment. We carried out a series of 14 dissections (10 on embalmed cadavers and 4 on unembalmed cadavers), and a study of images from the Visible Human Project. Dissections always led to the same conclusions. After having dissected the trigonum sternocostale, we observed that no vascular element was present in the space, which was obstructed downwards by the parietal peritoneum and limited forwards by the aponeurosis of the transverse abdominal muscle. Inferior digitations of transversus thoracis were joined with the transversus abdominis. The SEA passed in front of the plane formed by these two muscles while the sternal and costal parts of the diaphragm were behind this plane. Whatever the level of the section of the Visible Human Project, there was always a musculoaponeurotic plane between Larrey's space and the superior epigastric artery and both veins. Larrey's space, or trigonum sternocostale, was limited medially by the lateral border of the sternal part of the diaphragm, laterally by the medial border of the costal part of the diaphragm, and anteriorly by the musculoaponeurotic plane formed by the transversus thoracis above and the transversus abdominis, below without a clear boundary between those muscles. The SEA, the terminal branch of the ITA, passed in front of this musculoaponeurotic plane.