Trunk nerves (intercostal, sympathetic, vagus nerve)
Vagus nerve (CN X)
Nervus vagus (NC X)
- Origin
- Emerges from the postolivary sulcus of the medulla oblongata and exits the cranium via the jugular foramen
- Insertion
- Descends within the carotid sheath, traverses the mediastinum (emitting recurrent laryngeal, cardiac, and pulmonary branches), and forms the esophageal plexus to enter the abdomen via the esophageal hiatus as anterior and posterior vagal trunks
- Function
- Chief parasympathetic nerve supplying the heart (negative chronotropy and dromotropy), respiratory tree (bronchoconstriction), and GI tract up to the splenic flexure (motility, acid secretion, enzyme release)
- Innervation
- Parasympathetic motor, branchiomotor (pharyngeal/laryngeal muscles), visceral sensory (aortic baroreceptors/chemoreceptors), and general somatic sensory (external ear)
- Movement & chain
- Continuous tonic autonomic modulation
- Palpation
- Assessed indirectly via carotid sinus massage (triggers vagal reflex slowing AV node conduction)
- Clinical
- Vasovagal syncope (cardioinhibitory and vasodepressor response causing fainting), vagus nerve stimulation (VNS for refractory epilepsy), recurrent laryngeal nerve injury causing hoarseness or bilateral vocal cord paralysis, post-vagotomy gastroparesis.
- Segmental innervation
- Brainstem (dorsal motor nucleus, nucleus ambiguus, solitary tract nucleus)
- In clinical practice
- Management of acute vasovagal collapse (supine leg elevation, IV atropine for severe symptomatic bradycardia), post-thyroidectomy vocal cord and swallowing evaluation
- Region in the model
- Trunk nerves (intercostal, sympathetic, vagus nerve)