Arterial blood supply patterning of the mammary sentinel lymph nodes with special reference to the relation of the formation mechanism of the superficial subscapular artery.

This study aimed to conduct a detailed anatomical examination of the arterial supply to level Ib lymph nodes corresponding to mammary sentinel lymph nodes. This was achieved by focusing on the relationship with course changes of the axillary artery trunk using 41 cadavers (49 axillae). The course patterns of the axillary artery were classified as: "Standard type," which penetrate the brachial plexus (occurrence rate, 51%); "Superficial brachial artery type," which ran along the superficial layer of the brachial plexus (2%); "Superficial subscapular artery (SSbsA) type," which entered the deep layer without penetrating the brachial plexus (42.9%); and others (4.1%). The lateral thoracic artery, thoracodorsal artery, inferior pectoral artery, and superficial thoracic artery were distributed in a regular pair relationship according to each running type of the axillary artery for the Ib lymph nodes. Comparing blood supply ratio to the Ib lymph nodes, using SSbsA occurrence as a reference, showed that significant differences were observed with the inferior pectoral artery control for the standard subscapular artery group and the lateral thoracic artery control for the SSbsA group (p < 0.0001). It was suggested that in selective modeling of vascular networks during upper limb developments, two formation tendencies occur. The standard axillary and SSbsA axillary artery trunks are induced when the inferior pectoral artery-derived feeding arteries in the superficial brachial artery system are selected for Ib lymph nodes, or lateral thoracic artery-derived feeding arteries, which are closely related to the SSbsA pathway, are acquired.