A standardized, surgically relevant map for emergence of organ-specific branches from the human vagus nerve

Vagus nerve stimulation modulates airway, cardiac, pulmonary, and gastrointestinal functions through respective organ-specific branches. Knowledge of where along the nerve branches emerge could support alternative surgical placement of stimulation devices to activate targeted functions, while avoiding off-target effects. However, no quantified map of the emergence of vagal branches and their relationship to surgically relevant anatomical landmarks exists in humans.

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 one of seven groups (sympathetic, muscular, vascular, cardiac, pulmonary, esophageal, or multiple targets) and several sub-groups. Distances between branch emergence and jugular foramen (JF) were normalized to three anatomical landmarks: carotid bifurcation, laryngeal prominence, and superior border of clavicle.

Emergence of branches follows a proximal-to-distal order (median [IQR] distance from JF): sympathetic (3.9 cm [3.0-6.6]), muscular (6.2 [3.4-17.0]), vascular (9.6 [5.5-15.1]), cardiac (20.1 [16.9-22.5]), pulmonary (25.0 [22.8-27.6]), and esophageal (26.5 [24.3-29.1]). Branches emerge into two embryological domains separated at the clavicle: pharyngeal arch branches cluster proximally (7.3 cm [3.9-14.0]) and primitive mediastinum branches cluster distally (24.2 cm [20.9-27.1]), with sympathetic, muscular, and vascular sub-groups occupying distinct zones within the proximal domain. The longest branch-free intervals are all left-sided, occurring around the laryngeal prominence (3.0 cm [1.8-5.7]), the superior border of the clavicle (2.7 cm [1.3-5.2]), and the carotid bifurcation (2.2 cm [0.9-5.7]). Several "target" branches are maximally separated from "off-target" branches at specific distances: sympathetic vs. cervical/muscular/vascular at 6/8 cm (L/R), cardiac vs. carotid sinus at 14/10 cm, and recurrent laryngeal vs. other muscular at 18/13 cm. Minimal differences are found between male and female donors.

This study describes a quantified, landmark-registered map of cervical and thoracic vagal branch emergence and provides an anatomical reference that may help guide design and placement of more selective stimulation devices.