Multiple Variations in Third Segment of Axillary Artery
Authors: Miranda Valeria Lozada , Del Mazo Arbona Natalia , Jimenez‐Dietsch Sofia , Rodriguez Jailenne Quiñones 
Published: June 2021

Variations in the subscapular artery (SA) have been well documented and acknowledged as the most common variation in the axillary artery (AA). Although this is true, a variation of the third portion of the AA was found during dissection of the right upper limb of a female cadaver. This portion of the AA was found to give rise to a proximal SA, followed by a common trunk with 4 ramifications and distally, to the anterior circumflex humeral a. The common trunk gave rise to a second SA, posterior circumflex humeral a., scapular circumflex a., and the thoracodorsal a. Both SA branches were found to be irrigating the subscapularis m., implicating a possible dual and collateral supply. The posterior circumflex humeral a. was identified as it traversed posteriorly to reach the surgical neck of the humerus along with the axillary n. through the quadrangular space. The scapular circumflex a. was identified as it passed backward around the lower border of the scapula into the triangular space. Finally, the thoracodorsal a. gave off a branch to the latissimus dorsi m. and continued its course along the lateral thoracic wall to give off multiple branches to the serratus anterior m. It appears that the thoracodorsal branch reaching the serratus anterior m. is its main source of blood supply since the lateral thoracic a. was not found arising from the AA at any point. These findings are different from what is commonly documented. Usually, the AA is divided into three segments based on its relationship with the pectoralis minor m. The second portion of the AA gives rise to the thoracoacromial a., just posterior to the medial superior margin of the pectoralis m., and to the lateral thoracic a., passing downward behind the pectoralis minor m. along its inferolateral border. The third portion of the AA, which lies on the subscapularis m. and teres major m., gives rise to the anterior circumflex humeral a., the posterior circumflex humeral a., and the SA. The SA is commonly the largest branch of the AA, it runs downward on the costal surface of the subscapularis m. before it divides into the scapular circumflex a. and the thoracodorsal a. These arteries provide the major blood supply to the posterior wall of the axilla. Acknowledging the possibility of a variation from normal anatomy is relevant when interpreting imaging studies such as angiographs or during axillary surgical preparation due to possible pressure on the brachial plexus and vessels of the axilla when there is downward displacement of the head of the humerus. The suitability of the SA system as a donor for arterial grafts during upper limb circulation restoration is of great clinical importance. Their angle of rotation and their large, stable diameter render these arteries appropriate for a variety of flaps in plastic surgery. These clinical correlations can be further studied by exploring the embryology of these arteries. Normally, the subclavian a. arises from the 4th aortic arch and the 7th intersegmental a. It continues to develop as the limb bud grows; therefore, since the variations observed occur past the subclavian a., it seems that the vascular plexus was affected during development of the upper limb bud. Knowing this will help guide surgeons when exposed to such variations if a malformation during fetal limb development is suspected.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.