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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.
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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 General (wide distribution) From skin — pain, temp., touch From skeletal muscles & tendons, ligs. of joints -- proprioception Somatic (outer) Special (restricted distribution) From retina – sight From inner ear – hearing & equilibrium Afferent (sensory) From internal organs – visceral reflexes, fullness of hollow organs, pain General Visceral (inner) From taste buds – taste From olfactory mucosa -- smell Special To skeletal muscles not derived from pharyngeal arches General Somatic Efferent (motor) XXX – This category does not exist Special To smooth muscle, cardiac muscle & glands General Visceral To skeletal muscles derived from pharyngeal arches Special *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
NEURON #2 LIES IN A GANGLION GANGLION GANGLION
NEUROTRANSMITTER RELEASED AT GANGLION IS ACETYLCHOLINE GANGLION (ACH) GANGLION (ACH)
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 L 1 L2 S3 S2
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 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).
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
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 3. Descend and then synapse 4. Pass through sympthetic trunk without synapsing to enter a splanchnic nerve, and then synapse in a prevertebral ganglion Thoracic cardiac n. Splanchnic n. Prevertebral ganglion.
SYMPATHETIC INNERVATION (TO PERIPHERY)
SYMPATHETIC INNERVATION TO PERIPHERY (BODY WALL & EXTREMITIES)
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 INNERVATION (TO ABDOMINAL & PELVIC VISCERA)
TO VISCERA (ABDOMINAL & PELVIC) Prevertebral ganglion SPLANCHNIC N. (THORACIC, LUMBAR, & SACRAL) TO VISCERA (ABDOMINAL & PELVIC)
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. Superior hypogastric plexus 2nd and 3rd lumbar splanchnic nn. Hypogastric nn. (to inferior hypogastric plexus) 4th lumbar splancnic n.