Pectoral Region and Female Breast

Atlas References

Netter: 187–191, 194, 195, 258–260, 416, 418
McMinn: 126–129, 178–181
Gray's Atlas: 62–72, 394–396, 402

Skin and Superficial Fascia

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Make an incision from the jugular notch over the clavicle to the shoulder ( Fig. 4.1a ).
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Make a midline incision from the jugular notch to the xiphoid process ( Fig. 4.1b ).
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Extend the incision across the border of the costal margin toward the midaxillary line ( Fig. 4.1c ).
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Continue the incision from the shoulder distally to the upper one third of the arm. An encircling incision around the midportion of the arm permits removal of the skin from the upper arm ( Fig. 4.1d ).
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Start the dissection at the junction of the jugular notch and the clavicle. Reflect the skin of anterior thoracic wall, medial to lateral using combined blunt and sharp dissection ( Fig. 4.2 ).

Dissection Tip

As the superficial fascia and skin are retracted, you will encounter anterior cutaneous branches of ventral primary rami and vessels emerging near the sternum. The vessels are the perforating branches of the internal thoracic artery and the perforating tributaries to the internal thoracic vein. Cut through these cutaneous nerves and vessels.

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Reflect the skin and remove the superficial fascia from the thorax, shoulders, axillae, and proximal portions of the arms medially to the axilla ( Figs. 4.3 and 4.4 ). Continue to use combined blunt and sharp dissection.

Females

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In addition to the aforementioned incisions described in the reflection of the skin, make an oblique incision through the skin of the breast from the midpoint of the clavicle toward the anterior axillary line, encircling the areola ( Fig. 4.5 ).
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Lift the skin at the edge of the incision with your forceps and reflect medially to the axilla.
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Start reflecting the adipose tissue from the pectoralis major with a scalpel ( Figs. 4.6 and 4.7 ).

Anatomy Note

Note the retinacula cutis, which begins at the dermis and extends deeply into the breast, forming fibrous septae and irregular bands of dense connective tissue.

o
Cut through the middle of the areola, making a sagittal incision through the nipple-areolar complex, revealing glandular tissue, ducts, connective tissue, and fat of the breast ( Fig. 4.8 ). Partially remove the breast ( Fig. 4.9 ). Try to identify one or more lactiferous ducts ( Fig. 4.10 ).

Anatomy Note

The lactiferous ducts may possess an expanded part (the lactiferous sinus or ampulla) deep to the nipple. The ducts become very narrow as they pass through the nipple, each terminating separately upon its surface. In most aged cadavers, little will remain of the duct system or glandular tissue, being replaced with fibrous tissue infiltrated with fat.

Dissection Tip

Sometimes it is possible to identify an injection reservoir under the subcutaneous tissue ( Fig. 4.11 ). These allow direct access to a large vein without having to “stick” the vein each time and are used for long-term injections such as for chemotherapy.

Fig. 4.11, Left pectoralis major with overlying central venous port.

Superficial Dissection

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Identify the pectoralis major muscle, which is invested in a thin tough fascia, the pectoral fascia (part of the deep fascia system) ( Fig. 4.12 ).
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After cleaning the fascia from the pectoralis major, notice the separation of the pectoralis major from the deltoid muscle by the deltopectoral triangle (see Fig. 4.12 ).

Anatomy Note

The clavicle, the clavicular head of the pectoralis major muscle, and the deltoid muscle form this triangle. Within the deltopectoral triangle, the cephalic vein is found.

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Dividing the fascia that lies superficial to it will expose the cephalic vein. The cephalic vein is an important landmark for identifying the first part of the axillary artery (see Fig. 4.12 ).
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Detach the clavicular, sternal, and abdominal parts of the pectoralis major with a scalpel and reflect the muscle laterally to its insertion onto the humerus ( Fig. 4.13 ).
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Transect the clavicular portion of the pectoralis major muscle to the midclavicular line to avoid cutting important vessels and nerves, including the medial and lateral pectoral nerves ( Fig. 4.14 ).

Dissection Tip

When the pectoralis major is reflected, pay special attention so as not to transect the medial pectoral nerve as it passes through (or lies lateral or inferior to) the pectoralis minor muscle to enter the pectoralis major.