Profunda Brachii Vein Revisited: Anatomy of the Vein in the Posterior Upper Arm and Its Relationship to the Triangular Interval

Introduction: The profunda brachii vein (PBV) accompanies the profunda brachii artery through the radial groove and triangular interval. However, anatomical descriptions of the PBV remain limited and are sometimes inconsistent across textbooks and the literature, potentially leading to misunderstandings in medical education and surgical practice. Therefore, this study aimed to clarify the detailed anatomy of the PBV and classify variations in its course within the radial groove and triangular interval. Methods: A total of 129 upper limbs from 65 adult Japanese cadavers (26 males and 39 females; mean age, 86.2 ± 7.9 years) were examined. The triceps brachii muscle was dissected and incised to expose the PBV traveling alongside the profunda brachii artery. The PBV was identified and classified according to its number, branching patterns, and drainage pathways. The diameter of the PBV was also measured. Variations in PBV classification and diameter were statistically analyzed according to side and sex. Results: The PBV was present in all specimens and categorized into six types: (a) paired PBVs with a branch to the posterior circumflex humeral vein (PCHV) (33.3%); (b) a single PBV with a branch to the PCHV (27.9%); (c) a single PBV without a PCHV branch (15.5%); (d) paired PBVs without a PCHV branch (14.7%); (e) a single PBV terminating in veins other than the brachial or axillary veins beyond the triangular interval (5.4%); and (f) a single PBV draining directly into the PCHV without passing through the triangular interval (3.1%). Tributaries from the triceps brachii originated from the lateral head (93.0%), medial head (89.9%), and long head (50.4%). The median PBV diameter was 1.89 (interquartile range, 1.59-2.49) mm, with a maximum diameter of 6.35 mm and a minimum diameter of 0.68 mm. A significant side-to-side difference was observed (right: 1.93 (1.65-2.78) mm; left: 1.87 (1.49-2.45) mm; p = 0.044). Conclusion: This study clarified the anatomy and its variations of the PBV, contributing to a better understanding of this vein.