There are five groups of axillary lymph nodes, named after their locations in the armpit: apical, central, lateral, pectoral and posterior. Apical axillary nodes are near the neck, anterior near the chest, central in the center of the armpit, lateral near the outer arm and posterior below the shoulder blade.
Lymph nodes in the anterior group are also called pectoral axillary nodes, and the posterior group is also referred to as subscapular. There are about 15 to 30 axillary lymph nodes.
The apical axillary nodes drain lymph from the other groups into the lymphatic ducts in the neck. Because of this function and their location near the chest, they may be involved in the spread of breast cancer into other areas of the body.