INTRODUCTION TO THE
AUTONOMIC NERVOUS SYSTEM
STEVEN J. ZEHREN, PH.D.
GENERAL REMARKS
ABOUT THE NERVOUS SYSTEM
STRUCTURAL DIVISIONS:
CNS AND PNS
CENTRAL AND PERIPHERAL
NERVOUS SYSTEMS
FUNCTIONAL DIVISIONS:
SOMATIC AND VISCERAL
NERVOUS SYSTEMS
SOMATIC & VISCERAL
NERVOUS SYSTEMS
AUTONOMIC NERVOUS SYSTEM
(= VISCERAL MOTOR SYSTEM)
CLASSIFICATION OF FIBER TYPES (FUNCTIONAL COMPONENTS)
IN CRANIAL* AND SPINAL NERVES
Somatic
(outer)
Afferent
(sensory)
General
(wide
distribution)
From skin — pain, temp., touch
From skeletal muscles & tendons,
ligs. of joints -- proprioception
Special
(restricted
distribution)
From retina – sight
From inner ear – hearing & equilibrium
General
From internal organs – visceral reflexes,
fullness of hollow organs, pain
Special
From taste buds – taste
From olfactory mucosa -- smell
General
To skeletal muscles not derived from
pharyngeal arches
Special
XXX – This category does not exist
General
To smooth muscle, cardiac muscle & glands
Special
To skeletal muscles derived from
pharyngeal arches
Visceral
(inner)
Somatic
Efferent
(motor)
Visceral
*Special components occur only in certain cranial nerves.
STRUCTURE OF A TYPICAL
SPINAL NERVE (T1 – L2)
.
TYPICAL SPINAL NERVE
( T1 – L2)
TWO TYPES OF GANGLIA:
SENSORY & AUTONOMIC
COMPARISON OF SYMPATHETIC
& PARASYMPATHETIC SYSTEMS
SIMILARITIES
2 NEURON CHAIN
INNERVATION OF THE SUPRARENAL MEDULLA
NEURON #1 LIES IN CNS
NEURON #2 LIES IN A GANGLION
GANGLION
GANGLION
NEUROTRANSMITTER
RELEASED AT GANGLION
IS ACETYLCHOLINE
GANGLION
(ACH)
GANGLION
(ACH)
DIFFERENCES
THORACOLUMBAR (SYMPATHETIC) VS.
CRANIOSACRAL (PARASYMPATHETIC) OUTFLOW
Lateral horn of gray matter
(intermediolateral nucleus)
White matter
Dorsal (posterior) horn
of gray matter
Ventral (anterior) horn
of gray matter
C5
T2
T8
Ventral median fissure
L1
L2
S2
S3
LENGTH OF PRESYNAPTIC
& POSTSYNAPTIC FIBERS
NEUROTRANSMITTER
RELEASED AT EFFECTOR
ORGAN
USUALLY
NOREPINEPHRINE
ACH
AGGRESSIVE
WHEN AN ORGAN RECEIVES A DUAL
INNERVATION, THE SYSTEMS
USUALLY HAVE ANTAGONISTIC
PHYSIOLOGICAL EFFECTS
INCREASE
HEART RATE
VEGETATIVE
DECREASE
HEART RATE
AREAS OF DISTRIBUTION
OF SYMPATHETIC VS.
PARASYMPATHETIC FIBERS
Sympathetic system reaches virtually all parts of the body
(with the rare exception of such avascular tissues as cartilage and nails).
Parasympathetic system distributes only to the head and neck, visceral cavities of the trunk,
and the erectile tissues of the external genitalia (with the exception of the latter, it does not
reach the body wall or limbs).
PARASYMPATHETIC SYSTEM
CRANIAL OUTFLOW
(TO HEAD, NECK, THORAX,
& UPPER ABDOMEN)
PARASYMPATHETIC SYSTEM
L. colic flexure
PARASYMPATHETIC GANGLIA IN HEAD
III --- CILIARY GANGLION
IX --- OTIC GANGLION
VII --- PTERYGOPALATINE GANGLION
---- SUBMANDIBULAR GANGLION
X --- UNAMED GANGLIA IN NECK, THORAX & ABDOMEN
“COPS”
SACRAL OUTFLOW
(TO LOWER ABDOMEN & PELVIS)
PARASYMPATHETIC SYSTEM
Pelvic splanchnic nn
SYMPATHETIC SYSTEM
GENERAL SCHEME OF
SYMPATHETIC NERVOUS SYSTEM
Splanchnic n.
Rami communicantes
.
GRAY & WHITE
RAMI COMMUNICANTES
CONNECT TO SPINAL NERVES
T1 - L2
(T1 – L2)
WHITE RAMI = PRESYNAPTIC FIBERS
GRAY RAMI = POSTSYNAPTIC FIBERS
.
ONLY GRAY RAMI COMMUNICANTES
CONNECT TO SPINAL NERVES
ABOVE T1 AND BELOW L2
Gray ramus
comunicans
(above T1 or
below L2)
_ _ _ _ _ _ Presynaptic sympathetic
_________ Postsynaptic sympathetic
Courses taken by presynaptic
sympathetic fibers within the
sympathetic trunks:
1. Ascend and then synapse
2. Synapse at level of entry
Thoracic cardiac n.
3. Descend and then synapse
Splanchnic n.
Prevertebral
ganglion.
4. Pass through sympthetic trunk
without synapsing to enter a
splanchnic nerve, and then
synapse in a prevertebral
ganglion
SYMPATHETIC INNERVATION
(TO PERIPHERY)
SYMPATHETIC INNERVATION TO PERIPHERY (BODY WALL & EXTREMITIES)
PERIPHERAL DISTRIBUTION OF SYMPATHETICS BETWEEN T1 & L2
SYMPATHETIC INNERVATION
(TO HEAD)
SYMPATHETIC SUPPLY TO HEAD
Internal carotid n.
Superior cervical ganglion
External carotid a. & plexus
Gray rami communicantes
Middle cervical ganglion
Vertebral ganglion
Vertebral a. & plexus
Cervicothoracic (stellate) ganglion
Ansa subclavia
SYMPATHETIC INNERVATION
(TO THORACIC VISCERA)
TO VISCERA (THORACIC)
TO VISCERA
(THORACIC)
Paravertebral
ganglion
SYMPATHETIC SUPPLY TO LUNGS
Thoracic cord
segments T1-T5
Sympathetic trunk
Pulmonary plexus
Sympathetic fibers
RED
SYMPATHETIC SUPPLY TO HEART
SYMPATHETIC INNERVATION
(TO ABDOMINAL & PELVIC VISCERA)
TO VISCERA
(ABDOMINAL & PELVIC)
Prevertebral
ganglion
TO VISCERA
(ABDOMINAL
& PELVIC)
SPLANCHNIC N.
(THORACIC,
LUMBAR, &
SACRAL)
SYMPATHETIC SUPPLY TO ABDOMINAL & PELVIC VISCERA
Celiac ganglia
Greater and lesser
thoracic splanchnic nn.
Superior mesenteric ganglion
Aorticorenal ganglion
Least thoracic splanchnic n.
Renal a. and plexus
Inferior mesenteric ganglion
1st lumbar splanchnic n.
2nd and 3rd lumbar splanchnic nn.
4th lumbar splancnic n.
Superior hypogastric plexus
Hypogastric nn.
(to inferior hypogastric plexus)
END OF LECTURE