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Visceral Nervous System SHANDONG UNIVERSITY Liu Zhiyu The Visceral Nervous System Composition Visceral motor nerves (autonomic nervous system Sympathetic part Parasympathetic part Visceral sensory nerves Visceral motor nerves preganglionic neuron preganglionic fiber postganglionic postganglionic fiber neuron The differences between somatic motor and visceral motor n. Somatic Visceral Effectors Skeletal muscles Cardiac, smooth muscles and glands Kind of fibers One Two: sympathetic and parasympathetic From lower center to effector Single neuron Two neurons: preganglionic neuron (fiber) postganglionic neuron (fiber) Fibers Thick myelinated Preganglionic: thin myelinated postganglionic: unmyelinated Distributive form Nerve trunk Nerve plexuses Control Voluntary Involuntary (unconsciousness ) (consciousness) Sympathetic part Lower center located in lateral horn of gray mater of spinal cord in segments T1~L3 The peripheral part of sympathatic part Sympathetic ganglia Prevertebral ganglia Paravertebral ganglia Paravertebral ganglia Position: Arranged on either side of vertebral column Number: Consist of 19~22 ganglia cervical ganglia :3 thoracic ganglia: 10~12 lumbar ganglia: 4 sacral ganglia: 2~3 Coccygeal ganglion (Ganglion impar ) 1 unpaired on the anterior face of coccyx Superior cervical ganglion Middle cervical ganglion inferior cervical ganglion Sympathetic trunk Formation: It is formed by paravertebral ganglia and interganglionic branches Position: lie on either side of vertebral column from base of skull to coccyx The trunks of two side unite at the ganglion impar in front of the coccyx Prevertebral ganglia Lie anterior to vertebral column and near the arteries Celiac ganglion Aorticorenal ganglion Superior mesenteric ganglion Inferior mesenteric ganglion The communicating branches White communicating branches • preganglionic fibers (myelinated) sent out by the nurons of the lateral horn; • 15 pairs in number (T1—L3) Gray communicating branches • postganglionic unmyelinated fibers sent by the neurons of paravertebral ganglia, • 31 pairs in number. preganglionic fibers They pass to sympathatic trunk via white communicating branches and terminate in 3 ways: Some fibers synapse with neurons in the corresponding paravertebral ganglion; Some fibers pass up or down in sympathatic trunkbefore terminating in the paravertebral ganglion; The others pass through the paravertebral ganglion and terminate in prevertebral ganglion via the splanchnic n. postganglionic fibers They also terminate in 3 ways: Some fibers pass through the gray communicating branches to spinal n. and to the peripheral blood vessels,sweat gland and arrectores pilorum; postganglionic fibers surrounding the artery as a layer of nervous plexus to innervate the corresponding organs; terminating directly in the certain organs The general distribution of sympathatic nerve The cervical part of sympathatic trunk The postganglionic fibers pass through the gray communicating branches to 8 cervical nerves and distribute the head, neck and upper limb(blood vessels, sweat gland and arrector pilorum); The fibers surround the internal and external carotid arteries to innervate the glands of the head and neck, the dilator pupillae; The general distribution of sympathatic nerve The cervical part of sympathatic trunk Send out cardiac branches to heart (to form the cardiac plexus with cardiac branch of vagus n.) send out pharyngeal branch to the pharynx The thoracic part of sympathatic trunk Greater splanchnic nerve formed by preganglionic fibers from T5~T9 ganglia, and relay in celiac ganglion. Lesser splanchnic nerve formed by preganglionic fibers from T10~T12 ganglia, and relay in aorticorenal ganglion. The thoracic part of sympathatic trunk The postganglionic fibers supply the liver, spleen, kidney and alimentary tract as far as the left colic flexure. Lumbar splanchnic nerve Formed by preganglionic fibers from L1~L4 ganglia, and relay in prevertebral ganglia. The postganglionic fibers supply descending and sigmoid colon, rectum, pelvic viscera and lower limbs. Distribution of sympathetic nerve Preganglionic fibers T1~T5 T5~T12 L1~L3 Postganglionic fibers Head, neck, upper limb and thoracic viscera Abdominal viscera Pelvic viscera and lower limb Parasympathetic par Lower center : four pairs parasympathetic nuclei in brain stem in sacral parasympathetic nucleus of spinal cord in segments S2~S4 Parasympathetic part Parasympathetic ganglia: terminal ganglia are near or within the wall of a visceral organ –Para-organ ganglia : Ciliary ganglion Pterygopalatine ganglion Submandibular ganglion Otic ganglion –Intramural ganglia Cranial portion Ⅲ accessory oculomotor nucleus superior salivatory nucleus ciliary ganglion 〈○ Ⅶ sphincter pupillae and ciliary mscles pterygopalati ne ganglion 〈○ 〈○ Submandibular ganglion lacrimal gland submandibular gland Sublingual gland Cranial portion inferior salivatory nucleus dorsal nucleus of vagus n Ⅸ 〈○ parotid gland otic ganglion Ⅹ 〈○ terminal ganglia heart, lungs, liver, spleen, kidneys,alimen -tary tract as far as left colic flexure Sacral portion sacral parasympathetic nucleus Sacral n. S2-S4 Pelvic plexus Postganglionic fibers Pelvic splanchnic n. Synapse with terminal ganglia supply the descending and sigmoid colon, rectum and pelvic viscera Main differences between sympathetic and parasympathetic Sympathetic Parasympathetic Lower center Lateral gray horn of spinal cord segments T1~L3 Four pairs parasympathetic nuclei and sacral parasympathetic nucleus Ganglia Paravertebral, prevertebral Terminal Preganglionic f. Shorter Longer Postganglionic f. Longer Shorter Pre: Postganglionic 1: many more 1: a few Distributions Throughout the body Limited primarily to head and viscera of thorax, abdomen, and pelvis Different action Prepares for emergency situation (fight or flight) Conserve and restore body energy (rest and relaxation) Visceral plexuses Cardiac plexuses - Superficial , below aortic arch - Deep, anterior to bifurcation on trachea Pulmonary plexus Celiac plexus Abdominal aortic plexus Hypogastric plexus Superior hypogastric plexus Inferior hypogastric plexus (pelvic plexus) Referred pain Ciliary ganglion Pterygopalatine ganglion Submandibular ganglion Otic ganglion Main differences between sympathetic and parasympathetic