BackgroundReconstruction of the axillary fossa represents a surgical challenge given the functional implications for mobility of the upper limb. The posterior brachial flap has become a solution of choice in this indication, providing fine and functional local reconstruction, but little is known about its perforasome. This study aimed to identify the location of the perforator, analyze perfusion flow and linking vessel distribution, and propose an aesthetic refinement of the surgical technique by medializing the skin paddle in order to conceal esthetic scarring at the donor site. MethodsFifteen fresh cadavers were harvested and dissected. Twenty-six arms were injected with methylene blue. Two arms were injected with radiopaque dye. A dynamic (4-dimensional) computed tomographic angiography completed the analysis. ResultsThe perforasome was centered on the posterior axis of the arm with a perfusion area ranging from 82.2cm² to 142.9cm², with a median of 112.7cm² [96.7-125.6]. The median length of the pedicle was 83mm on average [65-91]. Its caliber at the emergence of the source vessel had a mean diameter of 1.43mm [1.27-1.61]. The distal limit of the paddle was located on average 10.7cm from the olecranon [7.8-12.2]. The scans showed direct linking vessels towards the perforasomes on the medial side of the arm, suggesting that it is possible to medialize the cutaneous paddle. ConclusionThe posterior brachial flap presents with a constant perforasome. It can be harvested more medially than previously described to improve aesthetic results, while maintaining reproducibility and satisfactory vascular reliability.