Celiac branches of posterior vagal trunk

Celiac branches of the vagus nerve arise mainly from the posterior vagal trunk. They run in a retroperitoneal plane, deep to the posterior wall of the upper part of lesser sac, to reach the celiac plexus. The celiac plexus, as you may know, is a meshwork of neurons and ganglia situated around the root of the celiac trunk.

The celiac branches of vagus nerve contain pre-ganglionic parasympathetic motor neurons, which arise from the dorsal motor nucleus of vagus in the medulla oblongata (brainstem). These general visceral efferent neurons join the celiac plexus, however, they do not synapse over here. The postganglionic fibers are extremely short in length and are situated within the walls of the target organs. They provide autonomic innervation to the gut and associated viscera, such as stomach, upper small intestine, liver and pancreas. Parasympathetic stimulation ends up increasing glandular secretions (including pancreatic enzymes and bile production), promoting peristalsis and opening up the sphincters.