The Visceral Nervous System

The Visceral Nervous System Composition Visceral motor nerves (autonomic nervous system) Sympathetic part 交感部 Parasympathetic part 副交感部 Visceral sensory nerves

Visceral motor nerves

Main differences between somatic motor and visceral motor n. Effectors Skeletal muscles Cardiac, smooth muscles and glands Kind of fibers One Two: sympathetic and parasympathetic From lower center to effect require Single neuron Two neurons: preganglionic neuron (fiber) and postganglionic neuron (fiber) Fibers Thick myelinated Preganglionic: thin myelinated postganglionic: unmyelinated Distributive form Nerve trunk Nerve plexuses Control Voluntary (consciousness) Involuntary (unconsciousness )

Sympathetic part 交感部 Lower center: located in lateral gray horn of spinal cord segments T1~L3 Sympathetic ganglia Paravertebral ganglia 椎旁节 Prevertebral ganglia 椎前节

Paravertebral ganglia 椎旁节 Arranged on either side of vertebral column Consist of 19~22 of oval-shaped ganglia Three cervical 10~12 thoracic 4 lumbar 2~3 sacral Ganglion impar奇神经节: unpaired on the anterior face of coccyx

Sympathetic trunk 交感干 Formed by paravertebral ganglia and interganglionic branches Lie on either side of vertebral column from base of skull to coccyx The trunks of two side unite in front of the coccyx at a small swelling, the ganglion impar

Prevertebral ganglia 椎前节 Lie anterior to vertebral column and near the arteries for which they are named Celiac ganglion 腹腔神经节 Aorticorenal ganglion 主动脉肾节 Superior mesenteric ganglion 肠系膜上神经节 Inferior mesenteric ganglion肠系膜下神经节

Three fates of preganglionic fibers 15 pairs white communicating branch Preganglionic fibers Sympathetic trunk (only spinal levels T1~L3 have white communicating branch)

Three fates of preganglionic fibers Relay in corresponding ganglion Ascend or descend in sympathetic trunk and relay in higher or lower ganglia Pass without synapse to a prevertebral ganglion for relay

Greater splanchnic nerve 内脏大神经 formed by preganglionic fibers from T5~T9 ganglia, and relay in celiac ganglion. Lesser splanchnic nerve 内脏小神经 formed by preganglionic fibers from T10~T12 ganglia, and relay in aorticorenal ganglion. The postganglionic fibers supply the liver, spleen, kidney and alimentary tract as far as the left colic flexure.

Lumbar splanchnic nerve 腰内脏神经 Formed by preganglionic fibers from L1~L4 ganglia, and relay in prevertebral ganglia. The postganglionic fibers supplydescending and sigmoid colon, rectum, pelvic viscera and lower limbs.

Three fates of postganglionic fibers Back to a spinal nerve along gray communicating branches ( 31 pairs ) to terminate in blood vessels, arrectores pilorum and sweat glands of head, neck, trunk and limbs The fibers from their networks around blood vessels passing to visceral end organs Terminate directly in certain organs

Distribution of sympathetic nerve Preganglionic fibers Postganglionic fibers T1~T5 Head, neck, upper limb and thoracic viscera T5~T12 Abdominal viscera L1~L3 Pelvic viscera and lower limb

Parasympathetic part 副交感部 Lower center: located in four pairs parasympathetic nuclei in brain stem and in sacral parasympathetic nucleus of spinal cord segments S2~S4 Parasympathetic ganglia: terminal ganglia are near or within the wall of a visceral organ Para-organ ganglia 器官旁节： Ciliary ganglion 睫状神经节 Pterygopalatine ganglion 翼腭神经节 Submandibular ganglion 下颌下神经节 Otic ganglion 耳神经节 Intramural ganglia 壁内节

Cranial portion颅部 Ⅲ sphincter pupillae and ciliary muscles ciliary ganglion lacrimal gland Ⅶ pterygopalatine ganglion sublingual gland submandibular gland Ⅸ submandibular ganglion Ⅹ parotid gland otic ganglion heart, lungs, liver, spleen kidneys,alimentary tract as far as left colic flexure terminal ganglia

Cranial portion颅部 Ⅲ accessory oculomotor nucleus 〈○ sphincter pupillae and ciliary muscles ciliary ganglion pterygopalatine ganglion Ⅶ 〈○ lacrimal gland superior salivatory nucleus 〈○ sublingual gland submandibular ganglion submandibular gland Ⅸ inferior salivator nucleus 〈○ parotid gland otic ganglion Ⅹ heart, lungs, liver, spleen, dorsal nucleus of vagus n. 〈○ kidneys,alimentary tract terminal ganglia as far as left colic flexure

Sacral portion 骶部 Preganglionic fibers from sacral parasympathetic nucleus leave spinal cord with anterior roots of the spinal nerves S2~S4, Then leave sacral nerves and form pelvic splanchnic nerve and travel by way of pelvic plexus to terminal ganglia in pelvic cavity Postganglionic fibers terminate in descending and sigmoid colon, rectum and pelvic viscera

Main differences between sympathetic and parasympathetic

Main differences between sympathetic and 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. 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 Pulmonary plexus Celiac plexus 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)

Visceral sensory nerves Nucleus of solitary tract Ⅶ，Ⅸ, Ⅹ Thalamus Cerebral cortex Enteroceptors Hypothalamus Posterior horn Effectors Sympathetic nerve Pelvic splanchnic nerve Somatic motor neurons visceral motor neuclei

Referred pain 牵涉痛