Breast and Neurovascular System of the Upper Extremity

BREAST (MASTECTOMY)

INCISION

Abduct the arm as much as possible and restrain with cheesecloth sling tied to the dissection table (Fig. 2.1). Modified radical mastectomy (mastectomy and levels 1 and 2 axillary lymph node dissection) incision is a horizontally oriented elliptical incision, which includes the nipple-areolar complex and redundant skin. The goal is to remove enough skin to have the healed site lie as smooth and flat as possible without compromising the blood supply to the skin. Skin and nippleareolar skin-sparing mastectomies are performed for patients undergoing reconstruction. Incise as shown in Figure 2.2.

Figure 2.1 Setup for mastectomy and axillary node dissection.

Figure 2.2 Skin incision for modified radical mastectomy.

OPERATIVE PROCEDURE

Create thin skin flaps of 0.5 to 1 cm in the plane of the subcutaneous fat-breast tissue interface. You want to preserve the blood supply to the dermal matrix on the skin. Form a superior and an inferior flap. Beginning medially, find the pectoralis fascia, the so-called clavipectoral fascia, and strip the breast along with the fascia from the pectoralis muscle (Fig. 2.3). During this subfascial dissection, approach the breast tissue from the medial aspect and elevate it laterally. This is best performed by blunt and sharp dissection with a knife. One technique is to sweep the blade perpendicular to the muscle.

CLINICAL HIGHLIGHTS

While performing the mastectomy, remember the blood supply to the breast. The major blood supply comes from above (superiorly) (Fig. 2.4).

The first portion of the subclavian artery gives rise to the internal thoracic artery (internal mammary artery), which gives off transthoracic perforators, second and third perforators generally being the largest. Preserving the branches of the vascular supply that go to the skin are a goal of modern mastectomies.
The axillary artery gives rise to the following:
- First portion—superior thoracic artery
- Second portion—thoracoacromial artery
  
  Figure 2.3 Creating skin flaps for mastectomy.
  
  Figure 2.4 Blood supply to the breast and upper extremity.
- Third portion—lateral thoracic artery at the lateral edge of the pectoralis minor sending perforators through and around the edge of the pectoralis major. Subscapular artery completes the scapular anastomosis (see Fig. 1.48)

The minor blood supply of the breast:

Small branches of the intercostal arteries perforate through to the retromammary space coming through the pectoralis and serratus muscles.

The nipple-areolar blood supply:

The blood supply to the nipple-areola complex comes from a periareolar plexus supplied by the above-named vessels. Preservation of one of these blood supply sources will prevent necrosis of the nipple after surgical incisions in the area and is very important for nipple-areolar skin-sparing mastectomies. Venous drainage corresponds to arterial supply.

The lymphatic drainage:

Lymphatic drainage generally follows the arteries. However, 75% of breast lymphatic drainage is to the axilla and the remainder to the internal thoracic nodes. Minor pathway is directly transthoracic to the intercostal lymphatics (Fig. 2.5). Remember that the clinical location of axillary nodes has been referred to levels 1, 2, and 3 from the lowest to the highest on the chest wall (Fig. 2.6). Sentinel node sampling is currently directing more specific node dissection techniques and de-emphasizes the clinical axillary node-level classification.

AXILLA (AXILLARY NODE DISSECTION)

INCISION

Abduct the arm and restrain as previously instructed. Extend the incision from the acromial process of the shoulder down the biceps brachii about halfway to the elbow.

OPERATIVE PROCEDURE

Begin the axillary dissection by peeling the axillary skin and fat inferiorly off biceps and pectoralis major muscles. Clear the tissue down to the lateral edge of pectoralis major muscle. Continue dissection down to the surface of the axillary vein (Fig. 2.7). Typically, you will find a draining tributary vein from the axilla on the inferior margin of the axillary vein. Transect this vein. Move the axillary tissue laterally away from the chest wall to expose the long thoracic nerve on the serratus anterior muscle. Occasionally, it can be palpated as a

bowstring along the muscle. Posterior and lateral to the transected tributary vein, the thoracodorsal vein, artery, and nerve may be identified (Fig. 2.8). Follow the thoracodorsal nerve down to the medial side of the latissimus dorsi muscle. Next, clear off the inferior and anterior portions of the axillary vein going medially to the chest wall. Intercostal brachial sensory nerves will be encountered crossing the axillary tissue and may be preserved.