The Visceral Nervous System

The Visceral Nervous SystemComposition 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.

Somatic Visceral

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 ova

l-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 ga

nglia 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 colu

mn 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 fibersPreganglionic fibers 15 pairs white communicating branch Sympathetic trunk

(only spinal levels T1~L3 have white communicating branch)

Three fates of preganglionic fibers Relay in corresponding g

anglion Ascend or descend in sy

mpathetic 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 ganglio

n.

Lesser splanchnic nerve 内脏小神经 f

ormed by preganglionic fibers from T10

~T12 ganglia, and relay in aorticorenal

ganglion.

The postganglionic fibers supply the liv

er, 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 L

1~L4 ganglia, and relay in prevertebr

al ganglia.

The postganglionic fibers supplydesce

nding and sigmoid colon, rectum, pelvi

c 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 nervePreganglionic 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

ciliary ganglion

sphincter pupillae and ciliary muscles

pterygopalatine ganglionⅦlacrimal gland

submandibular ganglion

sublingual glandsubmandibular glandⅨ

otic ganglionparotid glandⅩ

terminal ganglia

heart, lungs, liver, spleenkidneys,alimentary tractas far as left colic flexure

Cranial portion 颅部 Ⅲaccessory oculomotor nucleus 〈○ sphincter pupillae and ciliary muscles

ciliary ganglion

pterygopalatine ganglion Ⅶ 〈○ lacrimal glandsuperior salivatory nucleus 〈○ sublingual gland submandibular ganglion submandibular gland

Ⅸinferior 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

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)

Visceral sensory nerves

Enteroceptors

Ⅶ ，Ⅸ , Ⅹ

Nucleus of solitary tract

Sympathetic nerve Pelvic splanchnic nerve

Posterior horn

Thalamus

Hypothalamus

Cerebral cortex

Somatic motor neurons visceral motor neuclei

Effectors

Referred pain 牵涉痛