Background: This study was conducted to clarify the relationships between the extracranial portion of the facial nerve (EFN) and the zygomatic arch (ZA).
Method: Four cadaveric heads (8 parotid regions), examined under 3-40x magnification, were dissected from lateral to medial to expose the EFN.
Findings: In a vertical plane just anterior to the tragus, the distance from the superior edge of the ZA to the facial nerve (FN) is, on average, 26.88 mm. The FN then courses superiorly and anteriorly, crossing the ZA 18.65 mm anterior to the tragus on average. Thus, three points can be used to depict a triangle: A, at the level of the anterior border of the tragus, just above the superior edge of the ZA; B, 26 mm below A; and C, 18 mm anterior to A. This so called facial-zygomatic triangle represents the area where surgical dissection can be performed with no risk of damaging the FN. Thus, the closer one stays to the tragus, the lesser the risk of damaging the FN below the ZA. If the incision is carried out on a vertical plane closer to the tragus, the skin can be safely cut up to 2 cm below the ZA.
Conclusion: The facial-zygomatic triangle is a very useful superficial landmark to avoid FN damage when working below the ZA.