Surgical and radiologic anatomy : SRA, cilt.48, sa.1, 2026 (SCI-Expanded, Scopus)
PURPOSE: The supraorbital keyhole approach is a minimally invasive technique for treating lesions in the anterior and middle cranial fossa. A major complication of this procedure is injury to the temporal branch of the facial nerve. This study aimed to define safe surgical zones for the lateral borders of the incision to minimize facial nerve injuries. METHODS: This study examined 15 formalin-fixed adult cadaveric heads (30 sides). The temporal branches of the facial nerve were dissected using a surgical microscope. Three distances were measured using anatomical landmarks: (M1) horizontal distance between the supraorbital notch and facial nerve branches, (M2) vertical distance between the frontozygomatic junction and facial nerve branches, and (M3) horizontal distance between the lateral orbital rim and facial nerve branches. RESULTS: The mean distances were as follows: M1 = 48.96 ± 2.10 mm, M2 = 9.48 ± 0.83 mm, and M3 = 14.80 ± 0.99 mm. All measurements showed significant correlations (p < 0.001). Measurement precision was excellent (TEM 0.14-0.17 mm; rTEM 0.30%-1.74%; R 0.9628-0.9952). Despite intricate and variably interconnected temporal branch patterns, branches consistently lay outside the proposed safe zones. CONCLUSION: Based on the absolute minimum anatomical measurements, we defined the safe incision limits as 44 mm laterally from the supraorbital notch, 8 mm inferior to the frontozygomatic junction, and 13 mm laterally from the lateral orbital rim. Following these safe zones may reduce the risk of facial nerve injury and improve the outcomes of the procedure.