With retraction of the dissected tissue superiorly and placement of a broad ribbon retractor just below the inferior border of the mandible to retract the submandibular tissues medially, the inferior border of the mandible is visualized. The pterygomasseteric sling is sharply incised with a scalpel along the inferior border, the most avascular portion of the sling (Fig. 9-8). Incisions on the lateral surface of the mandible into the masseter muscle often produce bothersome hemorrhage. Increased exposure of the mandible is made possible by sequentially retracting the overlying tissues anteriorly and posteriorly, permitting more exposure of the inferior border for incision.
The sharp end of a periosteal elevator is drawn along the length of the periosteal incision to begin stripping the masseter muscle from the lateral ramus. Care is taken to keep the elevator in intimate contact with the bone or shredding of the masseter results, causing bleeding and making retraction of the shredded tissue difficult. The entire lateral surface of the mandibular ramus (including the coronoid process) and the body can be exposed to the level of the TMJ capsule (Fig. 9-9), being sure to avoid perforating into the oral cavity along the retromolar area if this is not desired. The only tissue separating the oral cavity from the dissection once the buccinator muscle has been stripped from the retromolar area is the oral mucosa. Retraction of the masseter muscle is facilitated by inserting a suitable retractor into the sigmoid notch (channel retractor, sigmoid notch retractor)(Fig.9-10).
More anterior in the mandibular body, care is needed to avoid damage to the mental neurovascular bundle, which exits the mental foramen, close to the apices of the bicuspid teeth.
Figure 9- 10 Sigmoid retractor. The curved flange inserts into the sigmoid notch, retracting the masseter muscle.
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