Neurovascular Anatomy

The motor supply is derived from the spinal accessory nerve but is sacrificed during flap harvest. The main vascular supply to the muscle is the transverse cervical artery. The transverse cervical artery runs a variable course across the posterior triangle: it originates either from the thyrocervical trunk (most commonly), directly from the subclavian artery, or as a branch of the dorsal scapular artery. At the anterior border of the levator scapulae muscle the transverse cervical artery divides into deep and superficial branches. The deep branch may arise separately from the subclavian artery as the dorsal scapular artery. The deep branch travels deep to the levator scapulae muscle and the superficial branch proceeds superficial to the levator scapulae muscle and divides into an ascending and descending branch.

The superior trapezius flap is nourished solely by the paraspinal perforators and, less so, by postauricular descending branches of the occipital artery. The lateral

Figure 14 Harvest of the superior trapezius flap involves reflection of the trapezius muscle and overlying skin toward the nape of neck and upper paraspinal area. The flap is then folded around the neck like a scarf to close the defect (photo on right).

Figure 15 Lateral island trapezius flap used to repair a chronic nonhealing ulcer in a patient who received radical radiation therapy for an ear canal carcinoma. Note on right that the flap is outlined over the trapezius muscle and a skin flap is being raised over the posterior neck to locate the feeding vessels.

Figure 15 Lateral island trapezius flap used to repair a chronic nonhealing ulcer in a patient who received radical radiation therapy for an ear canal carcinoma. Note on right that the flap is outlined over the trapezius muscle and a skin flap is being raised over the posterior neck to locate the feeding vessels.

island trapezius flap is based on the ascending branch of the superficial transverse cervical artery.

The lower island trapezius flap is based on the descending branch of the superficial transverse cervical artery. The deep transverse cervical artery (dorsal scapular artery) passes under the lesser rhomboid muscle and sends a branch to the inferior portion of the trapezius muscle (Fig. 19). Inclusion of the dorsal scapular artery by harvesting a segment of the lesser rhomboid muscle with the artery may be desirable to ensure adequate vascularity to the distal muscle (37). However, in a large series by Urken et al., no distal flap loss occurred with sacrifice of the dorsal scapular artery if the inferior border of the flap did not extend more than 5 cm below the border of the scapula (38). The primary venous drainage comes from the transverse cervical vein. This vein runs a variable course through the posterior triangle and may not accompany the artery. It empties into either the thyrocervical trunk or into the inferior part of the external jugular vein. To ensure the viability of a lower or

Figure 17 Lower island trapezius flap for repair of a planned temporal bone and postauricular skin excision. Note the outline of the flap (photo on right) over the lower aspect of the trapezius muscle.

lateral island flap, the inferior jugular vein must be preserved if this anatomical configuration exists which is especially important in patients undergoing neck dissection.

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