The development of muscle and musculocutaneous flaps resulted from an understanding of the blood supply to muscles and their overlying skin segments.26,27 This development in reconstructive surgery has significantly maximized flap survival and allowed reconstruc
tion of larger head and neck defects that could not be covered with local flaps alone.28 A complete muscle or a muscle segment may be rotated or transposed into a defect, based on its own inherent blood supply. The muscle surface may be either skin grafted or an overlying skin paddle may be included with the muscle as a myocutaneous unit. The cutaneous territory of the flap is perfused by a system of perforating vessels from the main vascular pedicle that runs through the muscle component. Myocutaneous flaps revolutionized head and neck reconstruction in the 1970s. The pectoralis major myocutaneous flap rapidly became the workhorse for reconstruction of intraoral and cheek defects and for covering synthetic materials used for mandible
reconstruction.29,30 Other myocutaneous pedicled flaps used less often for reconstruction of posterior or lateral defects in the head and neck region include the tem-poralis muscle, latissimus dorsi, trapezius, sternocleidomastoid and platysma muscles.28,31-34 Although regional muscle and myocutaneous flaps are useful options for head and neck reconstruction, they often cannot reach the defect due to a limited arc of rotation (imposed by the vascular pedicle), and may result in incomplete survival of the skin island. In addition, donor sites are very noticeable, particularly when skin grafting of the defect is required.
The temporalis muscle originates from the temporal fossa and inserts into the coronoid process of the mandible. It is surrounded by the galea and frontalis fascia and incorporates the underlying pericranium.31 If required, the outer table of the parietal bone may be incorporated together with the muscle. Its blood supply is provided by the deep temporal vessels. These vessels run deep to the pterygoid muscles and penetrate the undersurface of the temporalis muscle near the insertion. Elevation of the temporalis muscle flap
is simple; however, the temporal branch of the facial nerve is at risk for injury during flap harvest. Functional loss from use of this flap is minimal and the donor site can be closed primarily. The main drawback with this flap is the donor site contour deformity.35
The temporalis muscle flap may be transferred as a turnover flap using the coronoid process as rotation pivot. To maximize flap excursion, the central portion of the zygomatic arch should be temporarily removed and fixed back after elevating the muscle.36 Its main utility is to cover cheek, palatal and pharyngeal defects.36-38 It is a good option for obliteration of the orbit through the lateral orbital wall, and it is useful to cover exposed dura or cranial bone (Figure 18-17).
The pectoralis major (PM) myocutaneous flap is the most frequently used pedicled flap for head and neck reconstruction.29,39-41 The PM muscle originates from the clavicle, the first five ribs, the xiphoid, and from the upper abdominal muscles. It inserts on the humerus. Its blood supply is provided by branches of the thoracoacromial trunk, which pierces the clavipectoral fascia medial to the tendon of the pectoralis minor muscle. Multiple perforators run through the muscle in the subcutaneous fat, supplying the overlying skin with direct cutaneous vessels. The skin paddle can be located anywhere over the muscle pedicle. However, the design used most often is a vertical paddle up to 8 x 17 cm raised over the sternal origin of the muscle, which provides thin skin and allows primary closure of the donor defect. The skin island may extend into the inframammary fold and multiple skin paddles can be carried on the same muscle pedicle.42
The PM flap has been used to resurface cervical, facial, intraoral and pharyngeal defects (Figure 18-18).39-44 Although it can reach as far as the orbit, the most distal part of the flap may be compromised due to limited arc of rotation. In addition, it is often too bulky for intraoral reconstruction where thin, pliable tissue is needed to replace intraoral lining. The donor site may be closed primarily; however, a very noticeable scar and nipple-areola distortion is often observed. Large or multiple skin islands may result in the need for donor site skin grafting.
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