where do most parasympathetic fibers originate from
II. Preganglionic parasympathetic fibers originate in the brain and in the spinal cord. A. Preganglionic parasympathetic fibers contribute to cranial nerves III, VII, IX, and X. B. The long preganglionic fibers of the vagus (X) nerve synapse in terminal ganglia located next to or within the innervated organ.ll preganglionic autonomic nerve fibers are cholinergic (use ACh as a neurotransmitter). A. All postganglionic parasympathetic fibers are cholinergic. B. Most postganglionic sympathetic fibers are adrenergic (use norepinephrine as a neurotransmitter).