279

15 Diseases of the Autonomic Nervous System

Anatomy . . . 279

Normal and Pathological Function of the

Autonomic Nervous System . . . 282

Anatomy

The autonomic nervous system is responsible for the neural control of all of the organs and tissues of the body whose function is involuntary. It thus innervates the internal organs of the throat, thorax, and abdomen, the blood vessels, and the lacrimal, salivary, and sweat glands (among other organs). It can be divided on structural and functional grounds into a sympathetic and a parasympathetic nervous system. These two systems largely exert mutually antagonistic effects on their target organs. The fundamental structural unit of each system is a two-neuron chain, in which the first neuron has its cell body within the central nervous system, i. e., in the brainstem or spinal cord (the preganglionic neuron) and the second neuron has its cell body in an autonomic ganglion or plexus (the postganglionic neuron). The hypothalamus is the “command center” of the autonomic nervous system: it exerts a major degree of control on both

sympathetic and parasympathetic activity. Diseases of the autonomic nervous system very often manifest themselves in the form of disturbances of sweating, impairment of bladder, bowel, and sexual function, orthostatic hypotension, and Horner syndrome.

Sympathetic nervous system. The cell bodies of the preganglionic neurons lie in the lateral horns of the spinal cord at levels T1 to L2/3 (the intermediolateral nucleus; the entire system is thus sometimes called the thoracolumbar system). These cell bodies receive neural input from the hypothalamus, whose efferent projection (the central sympathetic pathway) descends through the brainstem and down the spinal cord to the sympathetic nuclei within the cord. The axons of the preganglionic neurons exit the spinal cord in the anterior roots and then travel by way of the rami communicantes into the sympathetic chain, which lies lateral to

dorsal root

dorsal spinal ganglion ramus of

spinal nerve

spinal nerve

intermediolateral nucleus

	ventral root			ventral
			gray ramus	ramus
				of spinal
			communicans
	white ramus communicans			nerve
			sympathetic
	preganglionic cholinergic		chain ganglion
	efferent fibers
	postganglionic noradrenergic
	efferent fibers
	postganglionic cholinergic		vascular branch
	efferent fibers
	cholinergic afferent fibers	splanchnic branch	interganglionic branch
	Fig. 15.1 Anatomy of the sympathetic efferent fibers leaving		tion, while the autonomic fibers to the blood vessels and internal
	the spinal cord. The sudomotor fibers accompany the spinal		organs follow their own paths to their respective targets (vascular
	nerves (dorsal and ventral rami) to their areas of cutaneous distribu-		ramus, splanchnic ramus).

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Diseases of the Autonomic Nervous System

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280	15 Diseases of the Autonomic Nervous System
			sympathetic nervous system
				superior tarsal m.
	hypothalamus		Horner syndrome	dilatator
				pupillae m.
		carotid plexus
	tegmental			orbitalis m.
	nuclei
			anhidrosis
	reticular		lacrimal gland
	formation
			nasal and palatal
	central		glands
	sympathetic		parotid gland
	pathway
	C1
	superior
	cervical	only
	ganglion	Horner	submandibular and sublingual glands
		syn-
	intermedio-	drome
	lateral nucleus		Horner syndrome
			+ anhidrosis	pulmonary/
	T1		stellate ganglion	cardiac plexus

	anhidrosis without
T3	Horner syndrome	spinal nerve
	gray/white rami
	communicantes	pilo-,	motor
		sudo-,
			fibers
		vaso-
T8		celiac		liver,
	greater	ganglion
	splanchnic n.			pancreas,
				spleen
	lesser
	splanchnic n.
L2
sweating		inferior
		mesenteric ganglion
superior
mesenteric		pelvic ganglia
ganglion
	sacral
superior	splanchnic nn.
hypogastric
plexus
	sympathetic trunk

Fig. 15.2 Anatomy of the sympathetic nervous system.

the spinal cord and consists of a chainlike arrangement	vicinity of the target organ (either in an autonomic
of ganglia and the fibrous connections between them	plexus or in an intramural ganglion, i. e., a ganglion lo-
(interganglionic branches). Some of the fibers form a	cated within the wall of the organ in question). The
synapse with a postganglionic neuron inside the sympa-	postganglionic neurons project efferent fibers to the tar-
thetic chain, while others ascend the entire sympathetic	get tissue, e. g., the smooth muscle of the internal organs
chain without a synapse, not meeting their correspond-	and blood vessels, and various glands. The relationship
ing postganglionic neuron till they have arrived in the	of the sympathetic fibers exiting the spinal cord to the

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Anatomy 281

parasympathetic nervous system

lacrimal gland

ciliary ganglion

ciliary m. sphincter pupillae m.

nasal and palatal glands

sublingual/submaxillary glands

parotid gland

superior/inferior ganglion

inferior hypogastric plexus

			III
		pterygopalatine
		ganglion
		VII
	submandibular	geniculate
	ganglion	ganglion
		IX
			C1
	otic ganglion
		X
	cardiacand pulmonaryplexus	pulmonary nn.
		cardiac nn.	T1

esophageal plexus

anterior/posterior vagal tract

gastric branches

celiac plexus

celiac ganglion

hepatic branches

renal plexus

aorticorenal ganglia

L1

	vesical plexus
		S1
		S2
postganglionic	pelvic ganglia	S3
		S4

cavernous nn.	pelvic	intermedio-
of the penis	splanchnic nn.
preganglionic		medial
		nuclei
prostatic plexus

Fig. 15.3 Anatomy of the parasympathetic nervous system.

nerve roots, sympathetic chain, and peripheral nerves is depicted in Fig. 15.1, while Fig. 15.2 provides an overview of the anatomy of the sympathetic nervous system.

Parasympathetic nervous system. The preganglionic neurons of the parasympathetic nervous system, unlike those of the sympathetic nervous system, are located in two parts of the central nervous system that lie at a con-

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siderable distance from each other. Some of the preganglionic neurons lie in the visceral motor and visceral sensory brainstem nuclei, the remainder in the lateral horns of spinal cord segments S2−S4 (the craniosacral system). The axons of the cranial preganglionic neurons exit the brainstem in cranial nerves III, VII, IX, and X and then travel onward to parasympathetic ganglia in the periphery, some of which are intramural, i. e., already lo-

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Diseases of the Autonomic Nervous System

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