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INTRODUCTION

Large defects in the upper region of the back, such as in cases of vertebrae exposure, pressure ulcers, or those that evolve with dehiscence and exposure of plates or screws, can require complex closure, as well as in meningeal exposure in high myelomeningoceles. Conventional treatment may require large flaps with skin grafting in the donor area and, sometimes, the time necessary for sufficient granulation1.

The trapezius muscle can be divided into three parts: ascending, transverse, and descending, with irrigation by the occipital, transverse cervical, dorsal scapular, and posterior intercostal arteries. According to the classification of Mathes & Nahai1, this vascularization is type II based on a dominant pedicle, the transverse cervical artery (TCA)1.

According to Horch & Stark2, after tumor extirpation, the ideal treatment is early closure, preferably performed with a muscle flap, which irrigates the defect.

The first trapezius musculocutaneous flap was described by Baek et al., in 1980, with application to the head and neck, but with vascularization limitations that are still referred to in other publications1-5.

According to studies by Weiglein et al.3, the dorsal scapular artery (DSA) is important in guaranteeing a larger cutaneous territory, and its preservation in the trapezius flaps can include it in the Mathes and Nahai type V classification.

According to Cormack & Lamberty6, the ascending and transverse parts of the muscle are irrigated by the occipital and transverse cervical arteries with branches piercing the skin that guarantee a cutaneous territory within the anatomical limits of the muscle. However, in the descending part, when the cutaneous portion exceeds the inferior angle of the scapula by 5 centimeters, it suffers and becomes necrotic, as the skin in this region is irrigated by direct perforators of the DSA which, although it has a larger cutaneous territory, is not preserved in flaps based on in TCA2,6.

Yang & Morris4 dissected 20 cadavers and described two irrigation patterns for the descending portion of the trapezius muscle and noted the constancy of the DSA whose cutaneous territory is described as having dimensions that exceed the limits of that attributed to the TCA, but they did not establish its limits.

Netterville & Wood5 studied the irrigation of the trapezius muscle and reported the DSA as the dominant pedicle on 15 sides of 30 dissections, the TCA on 9 sides, and 6 sides the dominance of both arteries. The authors emphasized the importance of the first in irrigating the musculocutaneous portion caudal to the inferior angle of the scapula.

Rocha et al.7 studied eight sides by dissection in cadavers and 60 sides by EcoDoppler in volunteers and found the constancy of the DSA with the two trajectory patterns already described. They found that both patterns allow mobilization of the flap in a musculocutaneous composition with a cutaneous territory that goes beyond the limits of the muscle in its lower third.

Bearing in mind these concepts and the difficulties encountered in cases of defect in the upper region of the back, the authors planned a trapezius musculocutaneous flap that, with the preservation of the DSA, would ensure a large cutaneous territory and allow primary closure of the donor area with mobilization in V-Y.