Autonomic Nervous System Pain Outlines Topics Nociception: Transduction Nociception: Transmission Nociception: Modulation The ANS Pain measurement Epidemiology of mental illness Deafferentiation pain Peripheral neuropathies and neuralgias Sympathetic dystrophies Central pain syndromes Post-herpetic neuralgia Extremity pain Low back pain Headache Pediatric pain Antidepressants Anticonvulsants Neurolytic blocks Celiac plexus block Neurosurgical procedures Epidural steroids Local anesthetics Psychological techniques Spinal stimulation TENS

ANS- Made up of sympathetic and parasympathetic nervous system. Purpose is to control circulatory, respiratory, alimentary and genitourinary functions. Consists of CNS and PNS portions.

Main CNS control of ANS is located within the hypothalamus

Cell bodies of preganglionic neurons are located in the intermediolateral gray of the spinal cord or in visceral efferent nuclei in the brain stem. The cell bodies of post-ganglionic neurons are located in peripheral ganglia.

Definitions

Ganglion- Site of synaptic connections specific to sympathetic or parasympathetic nervous system

Plexus- Grouping of ganglia and axons (sympathetic, parasympathetic, plus visceral afferents) converging at a well defined location.

Parasympathetic Nervous System

Preganglionic cell bodies are located in cranial nerve nuclei of the brain stem and IML gray of 2, 3, 4 sacral segments.

Cranial Neurons: Axons go to peripheral ganglia as part of the oculomotor, facial, glossopharyngeal, and vagus nerves.

Sacral neurons: axons exit via anterior spinal nerve roots and travel as pelvic splanchnic nerves to pelvic plexuses.

Sympathetic Nervous System

Preganglionic cell bodies begin in IML gray matter of T1 to L2. Some cell bodies may be located in C7-8 and L3-4 segments.

Axons pass via anterior spinal roots and rami communicantes to reach paravertebral ganglia of the sympathetic chain.

In the sympathetic chain, they may:

1. synapse
   
2. Travel up or down then synapse, or
   
3. pass to prevertebralk ganglia or plexuses (celiac, superior mesenteric, etc.) then synapse.

Major ganglion and plexuses

Stellate Ganglion
Superior, middle, intermediate, inferior ganglia from cell bodies located at T1-T6 make up the cervical sympathetic chain. This chain provides sympathetic inervation to the head, neck, and upper extremities. In 80% of patients, the inferior ganglia and 1st thoracic ganglia fuse to form the stellate ganglion. The contents of the stellate ganglion are axons of preganglionic sympathetic neurons and bodies of postganglionic sympathetic neurons.

Abdominal autonomic plexuses

Contain axons of preganglionic sympathetic neurons, bodies of postganglionic sympathetic neurons, parasympathetic fibers from the vagus and/or sacral parasymtathetic fibers, and visceral afferent fibers

Main plexuses:

Celiac (T12-L1)

Superior hypogastric (L4); supply pelvic viscera and the GU system

(L4, S1); supply pelvic viscera and the GU system

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