Axillary Artery Variation: The Rule not the Exception

Abstract

Introduction: Anatomic morphology commonly depicted in atlases or textbooks is often emphasized in gross anatomy classrooms; however, considerable variation may be observed in cadavers during dissection, particularly in the vascular system. This study statistically assesses the frequency of the classic versus variant axillary artery branching pattern and compares these observations to the incidence of variation described in the literature. Material and Methods: Axillary artery branching pattern was studied in 62 cadaver limbs. A Chi square goodness of fit test with post hoc analyses on the adjusted standardized residuals was used to evaluate branching patterns. Results: A statistically significant difference existed between the observed and expected frequencies of the classic presentation (P < 0.001). The axillary artery branching pattern exhibited the classic presentation in 17.7% of this sample; 82.3% of the limbs displayed a variant in at least one major axillary artery branch. The lateral thoracic and posterior circumflex humeral arteries were significantly variable branches observed in their textbook locations in 40.3% and 61.3% of cases, respectively. The superior thoracic, thoracoacromial, and subscapular arteries were significantly conserved branches documented in their textbook locations in 97%, 98.3%, and 98.3% of cases, respectively. Discussion and Conclusion: While anatomy educators and students understand that anatomic structure has an inherent range of variability, the classic axillary artery branching pattern students expect to find in cadavers and patients rarely occurs. Educators must present a realistic picture of anatomic complexity and emphasize the clinical and surgical implications of anatomical variation.