Ultrasound-Guided Integrated Musculoskeletal and Vascular Landmark Approach for Access to the Facial Nerve Trunk

Background: Ultrasound is increasingly used in plastic surgery for real-time guidance in minimally invasive procedures. However, standardized approaches for targeting the facial nerve (FN) trunk, particularly for motor nerve interventions, remain limited. This study aimed to evaluate the anatomical feasibility of an ultrasound-guided approach to the FN trunk using the posterior belly of the digastric muscle (PBDM) as a landmark. Methods: An exploratory feasibility design was used with a single fresh-frozen cadaver to perform ultrasound-guided dye injections targeting the anterior and posterior surfaces of the PBDM. Subsequent layer-by-layer dissection evaluated dye distribution relative to the facial and hypoglossal nerves. Additionally, real-time Doppler ultrasound in a live participant was conducted to visualize adjacent vascular structures, including the occipital and vertebral arteries. Results: The FN trunk was located deep to the PBDM and near the stylomastoid foramen. Anterior injections reached the FN trunk, whereas posterior injections followed the trajectory of the hypoglossal nerve. Doppler ultrasound enabled clear visualization of major vascular structures, supporting safe needle trajectory planning. Conclusions: This cadaveric feasibility study demonstrates a potentially reproducible ultrasound-guided anatomical approach to the FN trunk using consistent musculoskeletal and vascular landmarks. Incorporating Doppler vascular mapping enhances procedural safety and accuracy, providing a practical framework to facilitate clinical translation of image-guided motor nerve interventions in plastic and reconstructive surgery.