Arterial system of the breast.
1. the internal thoracic artery.
2. axillary artery.
3. the intercostal arteries.
Nerves of the mammary gland and axilla.
1. pectoral nerves; extra care should be taken to preserve each pectoral nerve in order to avoid atrophy of the pectoralis major and pectoralis minor muscles.
Injury to the inferior pectoral nerve → atrophy of the external lower pectoralis major muscle.
middle pectoral nerve injury → atrophy of the middle pectoralis major muscle.
Upper pectoralis nerve injury → atrophy of the upper internal pectoralis major muscle.
2. intercostal brachial nerve; the intercostal brachial nerve is a sensory branch, not a motor branch, and should be preserved. The intercostal brachial nerve runs almost parallel to the axillary vessels and emanates from the 2nd and 3rd intercostal spaces. The terminal side can be seen in the fatty tissue between the leptomeninges of the latissimus dorsi muscle and the axillary vein.
3. long thoracic nerve; the anterior serratus muscle is divided into 3 parts: superior, middle and inferior. The lower part is innervated by the long thoracic nerve. The long thoracic nerve is first located in the posterior lateral aspect of the axilla, in close proximity to the lateral chest wall, and is distributed to the area below the 3rd serration of the anterior serratus muscle. The long thoracic nerve is difficult to free at the end and is operated on the central side as much as possible. Along the lateral side of the long thoracic nerve, the subscapularis fascia is stripped up and down, as the long thoracic nerve is pushed to the lateral chest wall, deep axillary contouring can be easily.
4. thoracodorsal nerve; it emanates from the posterior root of the brachial plexus and travels down in the deep axilla with the subscapularis artery and then into the latissimus dorsi muscle with the thoracodorsal artery.
Surgical position
The upper limb of the affected side is sterilized, wrapped and immobilized with sterile gloves, abducted at 90°, and the affected side is elevated 20°-30°. This position allows for the dissection of the breast from the pectoralis major fascia until the breast is turned outward in the axillary region. During axillary contouring, the affected arm is raised with the elbow flexed 90° and fixed on the head frame. This position relaxes the pectoralis major muscle and facilitates the exposure of the axilla. When the skin is sutured, the affected arm is placed back on the scaffold with 70°-80° of abduction. The elbow joint is slightly flexed to balance the skin on both sides and is sutured.
Skin incision
Care is taken that the medial skin incision line is not too wide, that the medial skin incision line does not exceed the median line, and that the lateral skin incision line does not extend into the axilla as far as possible. The skin incision line should be as small as possible, and the length of the transverse incision should in principle start at the sternal border and end at the anterior axillary line.
Nowadays, the 0.7-1.0 cm thick flap method is used, taking care that no subcutaneous fat tissue remains on the flap as much as possible (5 cm outward from the skin incision line, the flap is peeled into a thin flap with a scalpel, and a small amount of subcutaneous tissue remains beyond 5 cm by peeling the flap with an electric knife.) With subcutaneous fat attachment, the lateral end of the incision is included in the axilla but does not exceed the mid-axillary line.
Mastectomy (excision of the pectoralis major fascia)
The pectoralis major fascia is excised from the clavicle of the pectoralis major muscle, and the pectoralis major fascia is cut along the muscle fibers, but care is taken not to cut into the muscle, usually, it is important to pull the breast tissue strongly to make the fascia tense, and almost all small blood vessels can be coagulated by electric knife to stop bleeding.
2. Complete excision of the fascia surrounding the cancer. The muscle part suspected of infiltration is pelvic resected.
3. Pay attention to the penetrating branch of the internal thoracic artery on the medial side.
4. Do not damage the anterior rectus abdominis sheath and external oblique abdominal muscle inferiorly.
5. At the outer edge of the pectoralis major muscle pay attention to the inferior pectoral nerve and blood vessels. When reaching the outer edge of the pectoralis major muscle, the fascia is almost always removed.
6. Do not peel the latissimus dorsi fascia too much in the part near the upper limb. Excessive stripping tends to cut the terminal side of the intercostal brachial nerve.
Preserve the intercostal brachial nerve in the 2nd,3rd intercostal space
Surgical points.
1. After defining the outer edge of the pectoralis minor muscle during contouring of the axillary lymph nodes, the lateral thoracic wall is treated, at which point the intercostal brachial nerve can be observed passing through the thoracic wall.
2. The height of the intercostal brachial nerve penetrating the chest wall is just dorsal to the same height of the outer edge of the pectoralis minor muscle, so that up to this horizontal height, the lateral chest wall can be boldly treated.
3. the lateral thoracic vein crosses between the branches of the intercostal brachial nerve.
4. In cases of positive axillary lymph node metastasis, the intercostal brachial nerve should be ligated and removed.
5. After identifying the intercostal brachial nerve, the nerve is separated forward along the nerve until it reaches the lateral aspect of the latissimus dorsi muscle, and the intercostal brachial nerve is pulled cephalad with a muscle pulling hook, and the fatty lymphatic tissue is contoured downward from the edge of the axillary vein, and the tissue is pulled downward from the dorsal aspect of the intercostal brachial nerve.
Basic points of preserving the dorsal thoracic artery
Only the vessels traveling toward the breast are ligated, and the final site of dissection is to the area where the dorsal thoracic artery branches out to the anterior serratus and latissimus dorsi muscles.
The subscapularis artery emanates from the axillary artery at a slight right angle. The subscapularis vein is thick (commonly known as the vascular pile). It is distributed downward to the rotating scapular artery and the thoracodorsal artery. The beginning of the subscapularis artery is revealed and the course of the thoracic dorsal nerve and the long thoracic nerve is confirmed.
Hemorrhagic triangle.
It is located between the long thoracic nerve and the thoracic dorsal nerve, the narrow subscapularis muscle in front of the fatty tissue called deep axillary fossa, is the pathway of lymphatic flow to the deep supraclavicular fossa, there are some small vessels running around the two nerves, especially the thoracic dorsal nerve, ligate and cut the small vessels at any time, care must be taken to avoid bleeding due to recklessness. This triangle should be kept in mind as it is the area where it is difficult to perform surgery in case of bleeding, hence the name bleeding triangle.
Preservation of the long pectoral nerve
First, the outer edge of the pectoralis major muscle is exposed, and the outer edge of the pectoralis minor muscle is exposed after excision of the fatty tissue between the pectoral muscles. Then the front of the axillary vein is revealed, and up to this point, the fat is cut to the peripheral edge according to the fatty cut-off margin. At this point, care is taken not to cut the intercostal brachial nerve at the lateral edge of the axilla. The bifurcation of the lateral thoracic vein can be seen in the middle of the axillary vein. After dissecting and ligating the lateral thoracic artery, the pectoralis minor muscle is dissected from the lateral edge to the posterior dorsal side. However, do not damage the anterior serratus fascia, and the site of the long thoracic nerve course is the posterior dorsal border. Starting from the subclavian bone, a longitudinal line of the long thoracic nerve, as thick as a pencil lead, can be seen 2-3 cm from the axillary vein to the posterior dorsal side.
Point: The long thoracic nerve is located in the coarsest fascial layer, and the long thoracic nerve represents the posterior dorsal border of the axillary contour. It is difficult to free the long thoracic nerve on the terminal side, so try to operate on the central side.