Dorsolateral musculocutaneous perforators of posterior intercostal artery: An anatomical study

Background: The posterior intercostal artery (PICA) is divided into four segments, vertebral, costal, intermuscular, and rectus, based on the neurovascular branching pattern. Dorsal branches arise from the vertebral segment. Several musculocutaneous perforators and a lateral branch originate from the costal segment. Musculocutaneous branches arise from the intermuscular and rectus segments. The purpose of this study is to describe in detail the musculocutaneous perforators of the costal segment of the posterior intercostal artery. Methods: Fresh cadavers were injected with a modified lead oxide-gelatin mixture. Intercostal spaces (8-11) were dissected in twelve cadavers (six preserved cadavers and six fresh cadavers). Angiograms were assembled with Adobe Photoshop. Two fresh cadavers underwent CT angiography and three dimensional reconstructions of the intercostal perforators were performed using Materialise's Interactive Medical Image Control System (MIMICS). Results: In twelve cadavers, a total of 356 perforators (size > 0.5 mm) were found to arise from the posterior intercostal arteries in 96 intercostal (IC) spaces. 154 perforators (>0.5 mm) were found in the costal segment of the PICA. An average of 6.4 perforators was found in each hemithorax. All perforators were found within 2 cm of the midscapular line. At least one perforator was found in all intercostal spaces. Two or more perforators were found in 40% of the 8th and 9th IC spaces and 60% of the 10th and 11th IC spaces. Perforators were oriented perpendicular to the direction of the muscle fibres of the latissimus dorsi and were usually present one or two intercostal spaces below their origin from the PICA. Conclusions: Perforators of the costal segment of the PICA are described in detail. We propose to call these currently unnamed musculocutaneous perforators "dorsolateral" branches of the PICA, as they are located between dorsal and lateral branches of PICA.