What is the primary blood supply to a Pectoralis Major Myocutaneous (PMMC) flap?

Blood Supply to the Pectoralis Major Myocutaneous (PMMC) Flap

The primary blood supply to a PMMC flap is the pectoral branch of the thoracoacromial artery, which serves as the dominant vascular pedicle in the vast majority of cases. 1, 2

Primary Vascular Pedicle

• The pectoral branch of the thoracoacromial artery provides the main arterial supply and is the basis for the flap's reliability in head and neck reconstruction 1, 2
• This vessel is present as a single pectoral branch in 87% of cases, with dual branches occurring in only 13% 1
• Before entering the muscle, the pectoral branch typically divides into two terminal branches in 67% of cases 1
• The average distance from the most distal perfused skin to the midclavicular point is approximately 24 cm, providing sufficient pedicle length for head and neck reconstruction 1

Secondary Contributing Vessels

While the thoracoacromial artery is dominant, two additional arterial systems contribute to the overall blood supply of the PMMC flap:

Lateral Thoracic Artery

• The lateral thoracic artery consistently supplies the lateral portion of the pectoralis major muscle in 100% of cases 1
• This vessel is particularly important for perfusion of the lower chest skin and distal/lateral skin islands 3, 4
• Preservation of the lateral thoracic artery during flap harvest significantly increases blood perfusion to the skin island, as demonstrated by quantitative indocyanine green angiography showing increased inflow rates when this vessel is preserved 4
• The lateral thoracic artery can be preserved without compromising pedicle length by dividing the pectoralis minor muscle during harvest 3

Internal Mammary Artery

• The internal mammary artery provides perforating branches that contribute to the medial aspect of the flap 2
• A rich anastomotic network exists between the internal mammary artery and the pectoral branch of the thoracoacromial artery 2
• This vessel also anastomoses with the lateral thoracic artery, creating a robust vascular network 2

Skin Territory Perfusion

• The skin overlying the pectoralis major muscle receives abundant blood supply from the underlying muscle vasculature 2
• The average perfused skin area measures approximately 13 x 20 cm, extending from the third to sixth rib and from the parasternal line to the anterior axillary line 1
• In 36% of cases, a major axial cutaneous vessel originating near the thoracoacromial artery extends caudally, providing additional direct cutaneous perfusion 2
• Both major arteries (pectoral branch and lateral thoracic) are enclosed within the muscle's fascial envelope, ensuring their protection during flap harvest 2

Clinical Implications for Flap Design

The conventional harvesting technique relies solely on the pectoral branch of the thoracoacromial artery, which provides indirect blood supply to distal skin through communicating vessels 3

For flaps with skin islands designed in the lower chest, preservation of the lateral thoracic artery is recommended to improve distal skin perfusion and reduce the risk of partial flap necrosis 3, 4

The focal point of rotation for flaps preserving both vessels remains at the same location just below the midpoint of the clavicle, allowing adequate reach to the oral cavity, tonsil, or hypopharynx without limitation 3