The cranial part of the ANS parasympathetic division consists of preganglionic fibers that originate in the brainstem and innervate various structures in the head, neck, thorax, and abdomen. These preganglionic fibers leave the brainstem as parts of cranial nerves III, VII, IX, and X. The parasympathetic fibers of cranial nerve III or the oculomotor nerve enter the ciliary ganglia, which sends postganglionic fibers to smooth muscles in the eye. The parasympathetic fibers of cranial nerve VII, known as the facial nerve, extend to the pterygopalatine ganglia and the submandibular ganglia. The pterygopalatine ganglia stimulate tear and mucus production in the lacrimal and nasal glands. The submandibular ganglia stimulate saliva production by innervating the submandibular and sublingual salivary glands. The parasympathetic fibers of cranial nerve IX, or the glossopharyngeal nerve, send parasympathetic signals to the parotid salivary gland through the otic ganglia. The parasympathetic fibers of cranial nerve X, or the vagus nerve, reach the terminal ganglia in the thorax and abdomen, supplying parasympathetic signals to the heart, lungs, and abdominal organs.