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 Afferent (sensory) Somatic (outer) Visceral (inner) General (wide distribution) Special (restricted distribution) From skin — pain, temp., touch From skeletal muscles & tendons, ligs. of joints -- proprioception From retina – sight From inner ear – hearing & equilibrium General From internal organs – visceral reflexes, fullness of hollow organs, pain From taste buds – taste From 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

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 Ventral median fissure T2 T8 C5 L 1 L2 S2 S3

LENGTH OF PRESYNAPTIC & POSTSYNAPTIC FIBERS

NEUROTRANSMITTER RELEASED AT EFFECTOR ORGAN USUALLY NOREPINEPHRINE ACH

WHEN AN ORGAN RECEIVES A DUAL INNERVATION, THE SYSTEMS USUALLY HAVE ANTAGONISTIC PHYSIOLOGICAL EFFECTS AGGRESSIVE VEGETATIVE INCREASE HEART RATE DECREASE HEART RATE

AREAS OF DISTRIBUTION OF SYMPATHETIC VS. PARASYMPATHETIC FIBERS virtually all parts of the body 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 --- C ILIARY GANGLION IX --- O TIC GANGLION VII --- P TERYGOPALATINE GANGLION ---- S UBMANDIBULAR GANGLION ---- S UBMANDIBULAR GANGLION X --- UNAMED GANGLIA IN NECK, THORAX & ABDOMEN “COPS” “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 (above T1 or below L2) Gray ramus comunicans

Courses taken by presynaptic sympathetic fibers within the sympathetic 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) ganglion Ansa subclavia Vertebral ganglion Vertebral a. & plexus SYMPATHETIC SUPPLY TO HEAD

SYMPATHETIC INNERVATION (TO THORACIC VISCERA)

TO VISCERA (THORACIC) TO VISCERA (THORACIC) Paravertebral ganglion

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)

Prevertebral ganglion TO VISCERA (ABDOMINAL & PELVIC) TO VISCERA (ABDOMINAL & PELVIC) SPLANCHNIC N. (THORACIC, LUMBAR, & SACRAL)

SYMPATHETIC SUPPLY TO ABDOMINAL & PELVIC VISCERA Greater and lesser thoracic splanchnic nn. Aorticorenal ganglion Least thoracic splanchnic n. Renal a. and plexus 2 nd and 3 rd lumbar splanchnic nn. 4 th lumbar splancnic n. Celiac ganglia Superior mesenteric ganglion Inferior mesenteric ganglion Superior hypogastric plexus Hypogastric nn. (to inferior hypogastric plexus) 1 st lumbar splanchnic n.

END OF LECTURE