Transcript The Visceral Nervous System

The 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
Somatic and Autonomic Nervous System
Main Differences Between Somatic Motor
and Visceral Motor n.
Somatic
Visceral
Effectors
Skeletal muscles
Cardiac, smooth muscles and glands
Control
Voluntary
(consciousness)
Involuntary (unconsciousness )
From lower
center to effect
require
Single neuron
Two neurons: preganglionic neuron
and postganglionic neuron
Kind of fibers
One
Two: sympathetic & parasympathetic
Fibers
Thick myelinated
Preganglionic: thin myelinated
postganglionic: unmyelinated
Distributive form Nerve trunk
Nerve plexuses
Somatic and Autonomic Nervous System
Somatic and Autonomic Nervous System
Somatic
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Skeletal muscle
Conscious and unconscious
movement
Skeletal muscle contracts
One synapse
Acetylcholine
Autonomic
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Smooth and cardiac muscle
and glands
Unconscious regulation
Target tissues stimulated or
inhibited
Two synapses
Acetylcholine by
preganglionic neurons and
ACh or norepinephrine by
postganglionic neurons
Neurotransmitters
SOMATIC NERVOUS SYSTEM
AUTONOMIC NERVOUS SYSTEM
Sympathetic
ACh
ACh
ACh
Parasympathetic
Ad. M. 
ACh
ACh
Striated
muscle
NE
Heart
Sm. mus.
Glands
ACh
Sweat
glands
ACh
Heart
Sm. mus.
Glands
E,

NE
Sympathetic Part

Lower center: located in
intermediolateral nucleus
(lateral gray horn) of spinal
cord segments T1~L3
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Sympathetic ganglia
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Paravertebral ganglia
Prevertebral ganglia
Paravertebral Ganglia
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Arranged on either side of
vertebral column
Consist of 19~22 of ovalshaped ganglia
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3 cervical
10~12 thoracic
4 lumbar
2~3 sacral
Ganglion impar : unpaired on
the anterior face of coccyx
Paravertebral Ganglia
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Superior cervical ganglion:
largest, situated in front of
transverse processes of C1~C3
vertebra
Middle cervical ganglion:
smallest, is at level of transverse
processes of C6 vertebra
Inferior cervical ganglion:
situated at level of C7 vertebra, and
may be fused with first thoracic
ganglion to form cervicothoracic
ganglion
Paravertebral Ganglia
Sympathetic Trunk
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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
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Lie anterior to vertebral column
and near the arteries for which
they are named
Celiac ganglion
Aorticorenal ganglion
Superior mesenteric ganglion
Inferior mesenteric ganglion
Preganglionic Fibers
Preganglionic fibers
15 pairs white communicating branches
(only spinal levels T1~L3 have
white communicating branch)
Sympathetic trunk
Three Fates of Preganglionic Fibers
1. Relay in corresponding
ganglion
2. Ascend or descend in
sympathetic trunk and
relay in higher or lower
ganglia
3. Pass without synapse to
a prevertebral ganglion
for relay
Preganglionic Fibers
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Greater splanchnic nerve
formed by preganglionic fibers
from T5~T9 ganglia, and relay
in celiac ganglion.
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Lesser splanchnic nerve
formed by preganglionic fibers
from T10~T12 ganglia, and
relay in aorticorenal ganglion.
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The postganglionic fibers
supply the liver, spleen, kidney
and alimentary tract as far as
the left colic flexure.
Preganglionic Fibers
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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.
Three Fates of Postganglionic Fibers
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Back to a spinal nerve along gray
communicating branches to
terminate in blood vessels, arrector
pili muscles and sweat glands of
head, neck, trunk and limbs
The fibers form their networks
around blood vessels passing to
visceral end organs
Terminate directly in certain organs
Postganglionic Fibers
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

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
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Ciliary ganglion
Pterygopalatine ganglion
Submandibular ganglion
Otic ganglion
Intra-organ ganglia
Cranial Portion of Parasympathetic Nerve
Ⅲ
sphincter pupillae
and ciliary muscles
ciliary ganglion
Ⅶ
lacrimal gland
pterygopalatine ganglion
Ⅸ
submandibular ganglion
sublingual gland
submandibular gland
parotid gland
Ⅹ
otic ganglion
terminal ganglia
heart, lungs, liver, spleen
kidneys,alimentary tract
as far as left colic flexure
Cranial Portion of Parasympathetic Nerve
Ⅲ
accessory oculomotor nucleus
〈○
sphincter pupillae and ciliary muscles
ciliary ganglion
Ⅶ
pterygopalatine ganglion
〈○
lacrimal gland
superior salivatory nucleus
〈○
submandibular ganglion
sublingual gland
submandibular gland
Ⅸ
〈○
otic ganglion
inferior salivator nucleus
Ⅹ
dorsal nucleus of vagus n.
〈○
terminal ganglia
parotid gland
heart, lungs, liver, spleen,
kidneys,alimentary tract
as far as left colic flexure
Sacral Portion of Parasympathetic Nerve
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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
Sympathetic
Parasympathetic
Lower center
Intermediolateral nucleus
(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 (expends energy)
Conserve and restore body
energy (conserves energy)
Main Differences Between
Sympathetic and Parasympathetic
Sympathetic
Parasympathetic
Different action
Prepares for emergency
situation (fight or flight)
Conserve and restore body
energy (rest and relaxation)
Pupil
Dilates
Constricts
Heart
Increases force of
contraction
Decreases force of
contraction
Rhythm of the heart To become more rapid
To make slow
Blood pressure
Heighten
Depress
Bronchi
Dilates bronchi
Constricts bronchi
Main Differences Between
Sympathetic and Parasympathetic
FUNCTION OF THE IRIS
Low light:iris dilates
Sympathetic neurone
Dilator pupillae
Normal light
Bright light:iris constricts
Sphincter pupillae
Pupil
Parasympathetic neurone
Ganglion
Visceral Plexuses
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Cardiac plexuses
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Superficial , below aortic
arch
Deep, anterior to bifurcation
of trachea
Pulmonary plexus
Visceral Plexuses
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Celiac plexus
Abdominal aortic plexus
Hypogastric plexus
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Superior hypogastric plexus
Inferior hypogastric plexus
(pelvic plexus)
Visceral Sensory Nerves
Nucleus of solitary tract
Ⅶ，Ⅸ, Ⅹ
Thalamus
Enteroceptors
Posterior horn
Cerebral
cortex
Hypothalamus
Effectors
Sympathetic nerve
Pelvic splanchnic nerve
Somatic motor neurons
visceral motor neuclei
Referred Pain
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Pain originating from organs
perceived as coming from skin
Site of pain may be distant from
organ
Referred Pain
Convergence theory:
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This type of referred pain occurs
because both visceral and somatic
afferents often converge on the
same interneurons in the pain
pathways.
Excitation of the somatic afferent
fibers is the more usual source of
afferent discharge, so we “refer”
the location of visceral receptor
activation to the somatic source
even though in the case of
visceral pain.
The perception is incorrect.
The convergence of nociceptor
input from the viscera and the skin.
Referred Pain