The Autonomic Nervous System is Organized into Three Divisions 4 As I have already stated the autonomic nervous system has three divisions, the sympathetic. Anatomically the preganglionic cells of the sympathetic division extend from the first thoracic spinal segment to the lower lumbar segments. The cell bodies of the preganglionic neurons are found within the spinal cord primarily within the intermediolateral gray matter. Axons of preganglionic neurons emerge form the spinal cord through the ventral root, enter the spinal nerve, and then separate from the somatic motor axons to project through the white rami communicantes branches to the paravetrebral chain ganglia. Each preganglionic fiber synapses with many postganglionic neurons that are distributed through different paravetebral ganglia.
Preganglionic fibers can pass through the ganglionic trunk or connective.
This permits coordinated activation of sympathetic neurons at several spinal levels. The axons of postganglionic neurons within the paravetebral ganglia exit thorough the gray rami communicantes and those that innervate the head travel along branches of the carotid arteries to their targets. Those innervating the rest of the body travel in the small spinal peripheral nerves to their targets. The cell bodies of the preganglionic neurons of the parasympathetic division are located within the brain stem in several nuclei and in segments S2-S4. of the spinal cord. Preganglionic axons leave the brain stem through their respective cranial nerves and project to postganglionic neurons in the cilliary, pterygopalatine, submandibular, and otic ganglia.