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Glossopharyngeal, vagus and accessory nerves
contributes fibres to abdominal viscera and to coeliac, superior mesenteric and myenteric plexuses. Branches pass in lesser omentum alongside lesser curvature of stomach to innervate pyloric antrum (nerves of Latarjet), and to give hepatic branches. 15.3
The fourth and sixth branchial arches: embryological considerations
The vagus is the nerve of the fourth and sixth branchial arches. Structures derived from these include the pharyngeal and laryngeal cartilages and muscles. The sixth arch artery on the left gives rise to the ductus arteriosus (ligamentum after birth) around which the left sixth arch nerve, the recurrent laryngeal, is caught when the artery descends. The sixth arch artery on the right degenerates, so the right recurrent laryngeal nerve is related to the most caudal persisting branchial arch artery, the fourth, which becomes the right subclavian. The motor function of the vagus in the neck is branchiomotor (special visceral motor): motor function in the thorax and abdomen is parasympathetic (general visceral motor). 15.4
Nerve fibres and central connections
Branchiomotor fibres: from nucleus ambiguus Nucleus ambiguus in medulla: branchiomotor nucleus of the third, fourth and sixth branchial arches. Axons pass to muscles of pharynx and larynx. Parasympathetic fibres: from dorsal motor nucleus of vagus. Dorsal motor nucleus of vagus (DMNX) in medulla gives preganglionic axons to innervate heart and thoracoabdominal viscera (foregut and midgut). Cell bodies of postganglionic neurons are generally in wall of destination organ, for example cardiac, myenteric plexuses.