The role of the vagus nerve includes innervation of the skeletal muscles of the pharynx, regulation of thoracic visceral activity, conduction of sensory impulses to thoracic and abdominal viscera, and conduction of general sensations in the auricle, external auditory canal, and pleura, and can regulate the three systems of circulation, respiration, and digestion. The vagus nerve contains four types of fibers: somatic motor fibers, which innervate the skeletal muscles of the pharynx and can move at will; visceral motor parasympathetic fibers, which are distributed in the thoracic and abdominal viscera and regulate the activities of these organs; visceral sensory fibers, which conduct sensory impulses of the thoracic and abdominal viscera; and somatosensory fibers, which conduct general sensations in the auricle, external auditory canal, and the pleura. The vagus nerve innervates the cervical and thoracic viscera and most of the abdominal viscera, regulating the three systems of circulation, respiration, and digestion by conducting sensory impulses to organs and viscera and by controlling the activity of cardiac muscle, smooth muscle, and glands. The specific effects are to slow down the heart rate, reduce cardiac output, lower peripheral vascular resistance, and lower arterial blood pressure; to accelerate the conversion of the inspiratory process to the expiratory process and increase the respiratory rate; and to cause contraction of the digestive tract and increased secretion of the glands, while the digestive sphincter is relaxed. Vagus nerve trunk injury is manifested as accelerated heart rate, nausea, vomiting, deep and slow breathing, etc. Due to paralysis of the pharyngeal muscles, hoarseness, speech difficulties, swallowing disorders, etc. can occur. When these symptoms occur, medical attention should be sought promptly.