Cervical non-invasive vagus nerve stimulation (nVNS) has emerged as a practical neuromodulation approach with FDA-cleared indications in primary headache disorders, yet skepticism persists over whether transcutaneous stimulation can reliably engage vagal fibers or whether observed benefits reflect nonspecific cervical activation. Here, we synthesize converging anatomical, biophysical, physiological, and clinical evidence demonstrating that nVNS does, in fact, activate vagal pathways without surg