Abstract
Introduction: Vagus nerve stimulation modulates laryngeal, cardiac, pulmonary, and gastrointestinal functions. Knowledge of where along the vagal trunk organ-specific branches emerge may support alternative surgical placements of stimulation devices that engage targeted functions while avoiding off-target effects. However, no quantified map relating vagal branch emergence to surgically accessible anatomical landmarks exists in humans. Methods: Fifty-eight vagus nerves (29 left, 29 right) from 29 embalmed donor bodies (15 females) were dissected from the jugular foramen through the thoracic cavity. Branches were traced to end organs and allocated to seven groups -sympathetic, muscular, vascular, cardiac, pulmonary, esophageal, and multiple targets - and several sub-groups. Distances between branch emergence and the jugular foramen (JF) were normalized to three anatomical landmarks: carotid bifurcation, laryngeal prominence, and superior border of clavicle. Results: Branch emergence follows a proximal-to-distal order: sympathetic (5.28 cm from JF), muscular (9.59 cm), vascular (10.70 cm), cardiac (19.65 cm), pulmonary (25.36 cm), and esophageal (26.57 cm). Vagal branches emerge into two embryological domains separated near the clavicle: pharyngeal arch-targeting branches cluster proximally (9.34 cm) and primitive mediastinum-targeting branches cluster distally (23.74 cm), with sympathetic, muscular, and vascular sub-groups occupying distinct zones within the proximal domain. The largest branch-free intervals occur above the left clavicle (2.33 +/- 2.80 cm) and below the left carotid bifurcation (2.58 +/- 3.17 cm). The greatest anatomical separation between cardiac (targeted) vs. muscular (off-target) branches occurs at 13 cm (left) and 15 cm (right) from JF, whereas for deep cardiac vs. superficial cardiac and pulmonary branches, at 21 cm (left) and 17 cm (right). Overall, no differences were found between male and female donors. Conclusions: This study provides a quantified, landmark-registered map of cervical and thoracic vagal branch emergence, offering a standardized anatomical template that may inform strategies for more function-selective vagal neuromodulation.
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