INTRODUCTION TO THE AUTONOMIC NERVOUS SYSTEM

STEVEN J. ZEHREN, PH.D.

GENERAL REMARKSABOUT 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

Afferent(sensory)

Somatic(outer)

Visceral(inner)

General(wide distribution)

Special(restricted distribution)

From skin — pain, temp., touchFrom skeletal muscles & tendons,ligs. of joints -- proprioception

From retina – sightFrom inner ear – hearing & equilibrium

General From internal organs – visceral reflexes,fullness of hollow organs, pain

From taste buds – tasteFrom olfactory mucosa -- smell

Special

Efferent(motor)

Somatic

Visceral

General

Special

General

Special

To skeletal muscles not derived from pharyngeal arches

XXX – This category does not exist

To smooth muscle, cardiac muscle & glands

To skeletal muscles derived from pharyngeal arches

*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) hornof gray matter

Ventral (anterior) hornof gray matter

Ventral median fissureT2 T8C5

L 1 L2 S2 S3

LENGTH OF PRESYNAPTIC& POSTSYNAPTIC FIBERS

NEUROTRANSMITTER RELEASED AT EFFECTOR ORGAN

USUALLYNOREPINEPHRINE

ACH

WHEN AN ORGAN RECEIVES A DUAL INNERVATION, THE SYSTEMS USUALLY HAVE ANTAGONISTIC PHYSIOLOGICAL EFFECTSAGGRESSIVE

VEGETATIVE

INCREASE HEART RATE

DECREASEHEART RATE

AREAS OF DISTRIBUTION OF SYMPATHETIC VS. PARASYMPATHETIC FIBERS

Sympathetic system reaches virtually all parts of the bodyvirtually all parts of the body(with the rare exception of such avascular tissues as cartilage and nails).(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 notreach the body wall or limbs).

PARASYMPATHETIC SYSTEM

CRANIAL OUTFLOW(TO HEAD, NECK, THORAX, & UPPER ABDOMEN)

PARASYMPATHETIC SYSTEM

L. colic flexure

PARASYMPATHETIC GANGLIA IN HEADPARASYMPATHETIC GANGLIA IN HEAD

III --- III --- CCILIARY GANGLIONILIARY GANGLION

IX --- IX --- OOTIC GANGLIONTIC GANGLION

VII --- VII --- PPTERYGOPALATINE GANGLIONTERYGOPALATINE GANGLION

---- ---- SSUBMANDIBULAR GANGLIONUBMANDIBULAR GANGLION X --- UNAMED GANGLIA IN NECK, THORAX & ABDOMENX --- UNAMED GANGLIA IN NECK, THORAX & ABDOMEN

“ “COPS”COPS”

SACRAL OUTFLOW(TO LOWER ABDOMEN & PELVIS)

PARASYMPATHETIC SYSTEM

Pelvic splanchnic nn

SYMPATHETIC SYSTEM

GENERAL SCHEME OFSYMPATHETIC NERVOUS SYSTEM

Splanchnic n.

Rami communicantes

.

GRAY & WHITERAMI COMMUNICANTESCONNECT TO SPINAL NERVEST1 - L2

(T1 – L2)

WHITE RAMI = PRESYNAPTIC FIBERSGRAY RAMI = POSTSYNAPTIC FIBERS

.ONLY GRAY RAMI COMMUNICANTESCONNECT TO SPINAL NERVESABOVE T1 AND BELOW L2

(above T1 or below L2)

Gray ramus comunicans

Courses taken by presynapticsympathetic fibers within thesympathetic trunks:

1. Ascend and then synapse

2. Synapse at level of entry

3. Descend and then synapse

4. Pass through sympthetic trunk without synapsing to enter a splanchnic nerve, and then synapse in a prevertebral ganglion

_ _ _ _ _ _ Presynaptic sympathetic

_________ Postsynaptic sympathetic

Splanchnic n.

Prevertebral ganglion.

Thoracic cardiac n.

SYMPATHETIC INNERVATION (TO PERIPHERY)

SYMPATHETIC INNERVATION TO PERIPHERY (BODY WALL & EXTREMITIES)

PERIPHERAL DISTRIBUTION OF SYMPATHETICS BETWEEN T1 & L2

SYMPATHETIC INNERVATION (TO HEAD)

Internal carotid n.

Superior cervical ganglion

Gray rami communicantes

External carotid a. & plexus

Middle cervical ganglion

Cervicothoracic (stellate) ganglionAnsa subclavia

Vertebral ganglionVertebral a. & plexus

SYMPATHETIC SUPPLY TO HEADSYMPATHETIC SUPPLY TO HEAD

SYMPATHETIC INNERVATION (TO THORACIC VISCERA)

TO VISCERA(THORACIC)

TO VISCERA (THORACIC)

Paravertebralganglion

Thoracic cord segments T1-T5

Sympathetic trunk

Pulmonary plexus

Sympathetic fibers

SYMPATHETIC SUPPLY TO LUNGS

RED

SYMPATHETIC SUPPLY TO HEART

SYMPATHETIC INNERVATION (TO ABDOMINAL & PELVIC VISCERA)

Prevertebralganglion

TO VISCERA(ABDOMINAL & PELVIC)

TO VISCERA(ABDOMINAL& PELVIC)

SPLANCHNIC N.(THORACIC,LUMBAR, &SACRAL)

SYMPATHETIC SUPPLY TO ABDOMINAL & PELVIC VISCERA

Greater and lesserthoracic splanchnic nn.

Aorticorenal ganglion

Least thoracic splanchnic n.Renal a. and plexus

2nd and 3rd lumbar splanchnic nn.

4th lumbar splancnic n.

Celiac ganglia

Superior mesenteric ganglion

Inferior mesenteric ganglion

Superior hypogastric plexus

Hypogastric nn.(to inferior hypogastric plexus)

1st lumbar splanchnic n.

END OF LECTURE