Craniosacral Outflow: The Four Cranial Parasympathetic Ganglia & Attendant Pathways

The human autonomic nervous system (ANS) comprises two major divisions – sympathetic and parasympathetic. The enteric division of the ANS, which provides automatic control of the gastrointestinal tract motility and function, is typically considered a subdivision of the parasympathetic division of the ANS. Whereas the sympathetic division of the ANS is described as having “thoracolumbar outflow” due to the origin of its preganglionic neurons in the thoracic and upper lumbar spinal cord, the parasympathetic division of the ANS is described as having “craniosacral outflow” due to the origin of its preganglionic neurons in the brainstem and sacral spinal cord. Cranial preganglionic parasympathetic neurons of the originate in specific nuclei of cranial nerves III, VII, IX and X located in the brainstem; these neurons, with the exception of the vagus nerve, synapse on postganglionic parasympathetic neurons located in the four cranial parasympathetic ganglia – ciliary, submandibular, pterygopalatine, and otic. The purpose of this presentation is to provide a detailed examination of the parasympathetic contributions of cranial nerves III, VII and IX to the four cranial parasympathetic ganglia and their attendant pathways.