 To approach the axilla, the stratification composition of the anterior wall of the axilla is demonstrated. First, the skin is peeled away, as well as the superficial layer of the subcutaneous fascia. Here we see the mammary gland and its connection to the nipple. Several glandular lobules have been dissected. By cutting this connection, we now see the deep layer of the subcutaneous fascia, and also the axillary fossa. In the fossa, there are numerous subcutaneous nerves and vessels. This deep fascia layer, together with the mammary gland, is peeled away, revealing the pectoral fascia. By peeling the pectoral fascia, we can see the pectoralis major. In the groove between the pectoralis major and deltoid is the cephalic vein. By cutting the clavicular origin of the deltoid muscle and reflecting it, we can see the insertion of the pectoralis major. Here, the rather independent clavicular portion is cut at its origin and then reflected. By cutting its insertion, we can easily see the supplying nerves. Using a finger to carefully separate the remaining insertion of the pectoralis major, we can cut and then slightly reflect it medially to reveal the nerves supplying the pectoralis major. Clearing the tissue behind this muscle, we see the pectoralis minor. And according to their location, in relation to the pectoralis minor, we see the superior pectoral nerves, the middle, and the inferior pectoral nerves. By cutting the origin of the pectoralis major, we can reflect this muscle laterally to view the posterior surface of the muscle. Note the fascia layer which lies between the pectoralis major and minor muscles. By clearing away fascia, we see pectoralis major nerves and their entry points. Returning all portions of the pectoralis major to their original position using pins, we can indicate the precise location of supplying nerve entry. We reflect this muscle again, cut the nerves, and then remove it in order to view the pectoralis minor and the adjoining fascial sheets. Here is the clavipectoral fascia. Between the coracoid process and the base of the axilla lies a coracoaxilar fascia. Its strong portion is sometimes called the suspensory ligament of the axilla. The inferior pectoral nerve pierces this fascia. By shifting the superior pectoral nerves and vessels, the fascia in front of the pectoralis minor is cleared to view this muscle. The pectoralis minor is cut at its insertion, reflected, cut at its origin, and then removed to allow view of the major nerves and vessels of the axilla. Here we see the brachial plexus and the axillary artery and vein. Now we will dissect the arteries and nerves of the axilla. Note the point of origin and distribution of the following axillary artery branches. Highest thoraxic artery, thoracochromial artery, lateral thoraxic artery, subscapular artery, and its continuation, thoracodorsal artery. In addition to the pectoral nerves, these nerves are critical too. Note the intercostal brachial nerve transverses in front of the two longitudinal nerves, the long thoraxic nerve and thoracodorsal nerve. In a male specimen, the arteries and nerves of the axilla are dissected. First we see lateral cutaneous branches via the digitation of the serratus anterior and obliquious externus abdominis. The fifth lateral cutaneous branch runs over the lateral margin of the pectoralis major to connect to the nipple. By reflection of the pectoralis major and minor, the lateral thoraxic vessels are revealed to originate from the axilla. Small branches from these vessels reach the nipple and mammary gland. To reach the axilla, the clavicular is cut and removed. Just beneath lies the subclavius muscle, which covers the axilla. The medial end of this muscle is cut and then reflected. With the finger inserted, the pectoralis minor is lifted and cut at its attachment to the coracoid process. We now see the vessels and nerves of the axilla. As the back muscles have been cut, the humerus and scapula can be pulled laterally, facilitating a complete view of the vessels and nerves of the axilla. To view the nerves and arteries, a tributary of the axillary vein is cut and the pectoralis major is bisected and reflected. Near the axillary artery, we trace the highest thoraxic artery. This artery and the subclavian vein border this triangular space. Nodes within this space are the final nodes before the venous angle. Returning the pectoralis major, we see the origin of the thoracoachromial artery and its pectoral branches. Reflecting the pectoralis minor, we see the lateral thoraxic artery descending and crossing the intercostal brachial nerves. To view the deep arteries, the axillary vein and tributaries are cut. We see the subscapular artery originating together with the lateral thoraxic artery. The subscapular artery bifurcates. The lateral branch is the circumflex scapular artery, which supplies the muscles on the dorsum of the scapula. The medial descending branch, the thoracodorsal artery, distributes to the serratus anterior and latissimus dorsi muscles. Now tracing the nerves, the long thoraxic nerve supplies the serratus anterior. And we see the thoracodorsal nerve, which distributes to the latissimus dorsi. From the brachial plexus, numerous nerves originate, forming a loop, and distribute to the pectoralis minor and major. Based on the relationship of the lymph nodes to the blood vessels and nerves, and also the pectoralis minor muscle, a classification was derived by the Japanese Breast Cancer Society. Considering this classification, first we will look at the axillary lymph node group, its relationship to the axillary vessels, brachial plexus, and their branches. Further, the manner of convergence of these lymphatic chains to the infra and supraclavicular nodes and finally to the venous angle will be examined. The superficial layer of the subcutaneous fascia is reflected, revealing the mammary gland. Now the deep layer is reflected. To reach the axillary vein, the clavicular portion of the pectoralis major is cut, as well as the remaining portion. Likewise, the pectoralis minor is cut and reflected, revealing the axillary vein as well as its lower adjacent groove. This groove is filled with fatty and connective tissues, which contain lymphatics. To examine the termination of the axillary lymphatics, we will look at the triangular area surrounded by the internal jugular and subclavian veins and the omohyoid muscle. Here we see the brachial plexus, together with the subclavian and axillary arteries. Along the jugular vein lies the deep cervical lymphatic chain. By pulling the jugular vein, we see the terminal portion of the thoraxic duct, which drains into the jugular subclavian venous angle. Close to this angle, several supraclavicular lymph nodes are seen. With the axillary artery and vein pulled cranially, we see the highest thoraxic artery, and more medially, the space containing the infraclavicular lymph nodes. Here we see the thoracoacromial artery and pectoral nerves, which distribute to the pectoral muscles. Here is the lateral thoraxic artery, long thoraxic nerve, and the thoracodorsal vessel and nerve. Now tracing the lymphatics from the subcutaneous tissues surrounding the mammary gland, first they converge at the axillary lymph nodes. Some lymphatics run together with the thoracoacromial artery, whereas most chains run alongside the inferior margin of the axillary and subclavian veins. These chains form a single thick vessel, which unites with the terminal portion of the thoraxic duct to drain into the venous angle. Therefore, these infraclavicular nodes are the final relay station for the axillary lymphatics. Now looking more deeply, near the brachial plexus, we see the median nerve and a rare superficial brachial artery. Here is the brachial artery. Originating from the brachial artery is the subscapular artery. Here we see the long thoraxic nerve, also the thoracodorsal artery and nerve. In the space between these, we find deep lymphatics. Tracing these deep lymphatics, we note that they ascend behind the large vessels and the brachial plexus. To view the more obscure deep lymph vessels, the major branches of the brachial plexus have been cut. Here is the radial nerve, the axillary nerve and the brachial artery. Here is the subscapular artery and the thoracodorsal nerve and also the long thoraxic nerve. In this specimen, the deep lymphatics lie close to the long thoraxic nerve. Tracing these lymphatics, we see they run intimately along the long thoraxic nerve and ascend superior to the brachial plexus. Then pierce the upper part of the brachial plexus to drain into the subclavian vein, slightly lateral to the venous angle. Now we will examine the interpectoral nodes in another specimen in the right side. Looking closely, we see the thoracoachromial artery. Along this artery is the interpectoral lymphatic chain. This interpectoral chain connects with the more medial infraclavicular lymphatics. Tracing the infraclavicular lymphatics, we find they unite to form a thick lymph vessel which ascends to drain into the venous angle. Finally, we will examine the lymphatic chain along the internal thoraxic vessels as the peristernal lymphatics are important in radical surgery. Returning to the first specimen, the left side, we see the internal jugular vein, the subclavian vein and venous angle, as well as the vagus. Here is the left brachiosophallic vein. As the anterior thoraxic cage has been opened, we can see the internal thoraxic vessels. The internal thoraxic artery originates from the subclavian artery and runs behind the subclavian vein, whereas the internal thoraxic vein drains into the left brachiosophallic vein. Lying between the left brachiosophallic vein and the internal thoraxic vein are the peristernal lymphatics. Here the left brachiosophallic vein has been cut and reflected. Tracing the lymphatics, they run both in front of and behind the subclavian vein to enter the venous angle. Looking at the peristernal region of the right side, we see the venous angle and well-developed supraclavicular nodes. Following the internal thoraxic vessels, we find the artery descends from the subclavian artery, but the internal thoraxic vein enters the brachiosophallic venous angle. There are numerous peristernal lymph nodes, some of which drain into the brachiosophallic angle nodes. These brachiosophallic angle nodes also receive lymphatics from the deep mediastinum. They send thick vessels which ascend to drain into the venous angle. By reflecting the subclavian vein and venous angle, we can trace the deep lymphatics along the internal thoraxic artery. Now we can review the two right peristernal lymphatic pathways to the venous angle. One runs via the brachiosophallic angle nodes and one runs directly along the internal thoraxic artery.