An Atypical Anatomical Variation in Facial Nerve Position: Temporal Branch Lateral and Main Trunk Medial to the Retromandibular Vein in a Series of Three Cadaveric Cases With Clinical Implications.

Objectives: The position of the retromandibular vein relative to the facial nerve branches can vary among individuals, adding a layer of complexity to surgical planning. In some cases, the vein may cross over or under certain nerve branches, necessitating meticulous dissection to avoid vascular or neural damage. Understanding these variations is critical for optimizing surgical outcomes, minimizing complications, and ensuring the preservation of both vascular and neural integrity. Methods: During the routine dissection of the right hemi-faces of 49 human donor bodies preserved for educational use, an unusual anatomical relationship between the extratemporal facial nerve and the retromandibular vein was observed and recorded in three cases (6%). The facial skin flaps were retracted laterally, and the parotid gland was meticulously dissected to expose and examine the nerves and vessels. The retromandibular vein's pathway was traced to identify the main trunk and branches of the extratemporal facial nerve within the parotid gland. The dissection also included the auriculotemporal nerve and the superficial temporal artery. Results: In all three cases, a single facial nerve trunk was identified, with its branching pattern classified as Type V and VI according to Davis (1956) in two cases; in one of the cases, the trifurcation of the main trunk of the facial nerve was observed. The extratemporal facial nerve followed an atypical route, passing deep (medial) to the retromandibular vein, while its temporal branch ran superficially (lateral) to the retromandibular vein. Conclusions: The aforementioned atypical course of the temporal branch places the nerve at a greater risk of injury during the surgical procedures. Recognizing and accounting for such variations is critical in minimizing complications and ensuring patient safety. Level of Evidence: Level 4 (case-series).