You are in: eMedicine Specialties > Plastic Surgery > BREAST Breast AnatomyArticle Last Updated: May 24, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 8
  Author: Linda Li, MD, Consulting Staff, Department of Plastic Surgery, Hospital of the Good Samaritan Linda Li is a member of the following medical societies: American Society of Plastic Surgeons Editors: Christian Paletta, MD, FACS, Professor, Division Chief and Program Director, Department of Plastic and Reconstructive Surgery, St Louis University School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Saleh M Shenaq, MD†, Former Director and Founder, The International Brachial Plexus Institute; Former Chief, Section of Plastic Surgery, Methodist Hospital, Houston; Nicolas (Nick) G Slenkovich, MD, Practice Director, Colorado Plastic Surgery Center at Swedish Medical Center; Al Aly, MD, FACS, Consulting Surgeon, Iowa City Plastic Surgery Author and Editor Disclosure Synonyms and related keywords: breast anatomy BREAST ANATOMYSection 2 of 8
  As with all surgical procedures, understanding the anatomy is crucial prior to performing an operative procedure. Comprehension of breast anatomy enhances the surgeon's ability to perform surgery safely and effectively. VASCULAR ANATOMYSection 3 of 8
The blood of the breast skin depends on the subdermal plexus, which is in communication with underlying deeper vessels supplying the breast parenchyma. The blood supply is derived from (1) perforating branches of the internal mammary artery, (2) the lateral thoracic artery, (3) the thoracodorsal artery, (4) intercostal artery perforators, and (5) the thoracoacromial artery. This rich blood supply allows for a variety of reduction techniques, ensuring the viability of the skin flaps after surgery. INNERVATION OF THE BREASTSection 4 of 8
Sensory innervation of the breast is dermatomal in nature. It is mainly derived from the anterolateral and anteromedial branches of thoracic intercostal nerves T3-T5. Supraclavicular nerves from the lower fibers of the cervical plexus also provide innervation to the upper and lateral portions of the breast. Researchers believe sensation to the nipple derives from the lateral cutaneous branch of T4. BREAST PARENCHYMA AND SUPPORT STRUCTURESSection 5 of 8
The breast is made up of both fatty tissue and glandular milk-producing tissues. The ratio of fatty versus glandular tissue varies among individuals. In addition, with the onset of menopause (ie, decrease in estrogen levels), the relative amount of fatty tissue increases as the glandular tissue diminishes. The soft tissues of the breast are supported by the suspensory ligaments of Cooper. These ligaments run throughout the breast tissue parenchyma from the deep fascia beneath the breast and attach to the dermis of the skin. Since they are not taut, they allow for the natural motion of the breast. Eventually, this results in breast ptosis since these ligaments relax with age and time. MUSCULATURE RELATED TO THE BREASTSection 6 of 8
The breast lies over the musculature that encases the chest wall. The muscles involved include the pectoralis major, serratus anterior, external oblique, and rectus abdominus fascia. The blood supply that provides circulation to these muscles then perforates through to the breast parenchyma, thus also supplying blood to the breast. By maintaining continuity with the underlying musculature, the breast tissue remains richly perfused, thus preventing complications arising from aesthetic or reconstructive surgery requiring the placement of a breast implant. Pectoralis major The pectoralis major muscle is a broad muscle that extends from its origin on the medial clavicle and lateral sternum to its insertion on the humerus. The thoracoacromial artery provides its major blood supply while the intercostal perforators arising from the internal mammary artery provide a segmental blood supply. The medial and lateral anterior thoracic nerves provide innervation for the muscle, entering posteriorly and laterally. The action of the pectoralis major is to flex, adduct, and rotate the arm medially. The pectoralis major is extremely important in both aesthetic and reconstructive breast surgery, since it provides muscle coverage from the breast implant. In reconstructive surgery, the pectoralis major muscle covers the implant, providing a decreased risk of extrusion of the implant since the skin and underlying subcutaneous tissues are often diminished greatly following mastectomy. The muscle provides additional tissue between the implant and the skin, thus decreasing the palpability of the implant. Often, placement of the implant beneath the muscle causes it to be noticeable when the pectoralis is contracted. In these instances, it may be helpful to release the pectoralis muscle from its inferior and medial attachments to decrease the incidence of noticeable contractions. In addition, with inferior release of the pectoralis muscle, lower positioning of the implant can be achieved, resulting in a more aesthetic appearance. Serratus anterior The serratus anterior muscle is a broad muscle that runs along the anterolateral chest wall. Its origin is the outer surface of the upper borders of the first through eighth ribs and its insertion is on the deep surface of the scapula. Its vascular supply is derived equally from the lateral thoracic artery and branches from the thoracodorsal artery. The long thoracic nerve serves to innervate the serratus anterior, which acts to rotate the scapula, raising the point of the shoulder and drawing the scapula forward toward the body. Transection of the long thoracic nerve is carefully avoided during an axillary lymph node dissection since its loss results in "winging" as the scapula is released from the chest wall and moves upward and outward. Because the serratus anterior underlies the lateral aspect of the breast, in aesthetic surgery, blunt elevation of the pectoralis major laterally inadvertently elevates a small portion of the serratus muscle. To completely cover the implant with muscle in reconstructive surgery, often the serratus anterior must be elevated sharply to obtain a sufficient muscle layer to provide coverage. Rectus abdominus The rectus abdominus muscle provides the inferior border to the breast. It is an elongated muscle that runs from its origin at the crest of the pubis and interpubic ligament to its insertion at the xiphoid process and cartilages of the fifth through seventh ribs. It acts to compress the abdomen and flex the spine. The 7th through 12th intercostal nerves provide sensation to overlying skin and innervate the muscle. Vascularity of the muscle is maintained through a network between the superior and inferior deep epigastric arteries. When placing an implant for breast reconstruction, in attempting to achieve complete coverage with muscle, the rectus fascia must often be elevated to place the implant sufficiently inferior. This dense thick fascia is often intimately adherent to the ribs below it. Once elevated and released, proper positioning and expansion of the implant can proceed. External oblique The external oblique muscle is a broad muscle that runs along the anterolateral abdomen and chest wall. Its origin is from the lower 8 ribs, and its insertion is along the anterior half of the iliac crest and the aponeurosis of the linea alba from the xiphoid to the pubis. It acts to compress the abdomen, flex and laterally rotate the spine, and depress the ribs. The 7th through 12th intercostal nerves serve to innervate the external oblique. A segmental blood supply is maintained through the inferior 8 posterior intercostal arteries. The external oblique muscle abuts the breast on the inferior lateral aspect. Elevated along with the rectus abdominus fascia to provide inferior coverage of the breast implant during reconstructive surgery, its fascia, like the fascia of the rectus abdominus muscle, must be released adequately to provide for proper placement and expansion of the implant. In aesthetic surgery, placement of the implant inferiorly is usually not below these fascial attachments. If the implant is placed behind the fascia, the implant often "rides too high" and may result in a "double bubble" effect, wherein the breast parenchyma slides over and off the implant. MULTIMEDIASection 7 of 8
REFERENCESSection 8 of 8
Article Last Updated: May 24, 2006 | ||||||||||||
