Fig. 2

Clough’s classification of axillary lymph nodes. The intersection between the lateral thoracic vein (LTV) and the second intercostobrachial nerve (ICBN) forms a cross that creates 4 zones: zone a is the area adjacent to the LTV, extending from the lower border of the axilla to the second ICBN; zone b is the area adjacent to the LTV, extending from the second ICBN to the axillary vein, extending medially under the pectoralis minor muscle; zone c is the lateral axillary area outside zone a; and zone d is the lateral axillary area outside zone b