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I. Autonomic Nervous System (ANS)
A. Dual Innervation
B. Autonomic Motor Pathway
1. Preganglionic Neuron
a. Preganglionic Fibers (Axons)
(1) Acetylcholine - ACh
2. Ganglion (Ganglia)
3. Ganglionic Neuron
a. Ganglionic Fibers (Axons)
(1) Sympathetic Fibers Release
Norepinephrine – NE
(a) Adrenergic Fibers
(2) Parasympathetic Fibers Release
Acetylcholine – ACh
(a) Cholinergic Fibers
4. Effectors
a. Glands
b. Smooth Muscle
c. Cardiac Muscle
C. Two Major Anatomical Differences
1. Location of Preganglionic Exit Points from CNS
a. Sympathetic (Thoracolumbar) Division
1) Exit at spinal cord segments T1
through L2 to enter the thoracic and
lumbar spinal nerves
b. Parasympathetic (Craniosacral) Division
1) Exit CNS through certain cranial or
sacral nerves
2. Location of Autonomic Ganglia in PNS
a. Sympathetic Ganglia lie close to spinal cord
1) Short Preganglionic neurons
2) Long Ganglionic neurons
b. Parasympathetic Ganglia lie near or within the
visceral effectors
1) Long Preganglionic neurons
2) Short Ganglionic neurons
D. Sympathetic (Thoracolumbar) Division
1. Fight – or – Flight Response
a. Exercise
b. Excitement
c. Emergency
d. Embarrassment
2. Organization of Sympathetic Division
a. Preganglionic Neurons
1) Originate in Pons & Medulla
2) Descend to Thoracic & Lumbar
Segments
3) Soma Located in Lateral Gray Horns
4) Axons Exit Cord in Ventral Roots
5) Travel in nerves T1 – L2 to Synapse
a) Sympathetic Chain (Trunk) Ganglion (Paravertebral
Ganglion)
(1) Ganglionic Neurons innervate Thoracic &
Integumentary Organs
b) Collateral (Prevertebral) Ganglia
(1) Preganglionic Fibers called Splanchnic Nerves
(2) Ganglia named for adjacent blood vessels
(a) Celiac Ganglion
(b) Superior Mesenteric Ganglion
(c) Inferior Mesenteric Ganglion
(d) Hypogastric Ganglion
(3) Ganglionic Neurons innervate Abdominopelvic
Organs
c) Adrenal Medulla
(1) Ganglionic Neurons release Adrenaline into the
Bloodstream
3. Sympathetic Pathways – Three Regions
a. Rami Communicantes for Chain Ganglia Pathway
(1) Preganglionic Fibers Pass through White Ramus
(a) Usually Synapses with Ganglionic Neuron
(2) Ganglionic Fibers Exit Via Either
(a) Gray Ramus
[1] Spinal Nerve
[a] General Somatic Structure
(b) Autonomic Nerve
[1] Innervate Thoracic Viscera
(3) Same Side Sympathetic Chain Ganglia
(a) Synapse with up to 32 Ganglionic Neurons
(b) Widespread Effects
b. Collateral Ganglia Pathway - Preganglionic fibers pass through
Chain Ganglia, enter Splanchnic Nerves then Synapse at Collateral
Ganglia
c. Adrenal gland – Preganglionic fibers do not Synapse in either
Chain Ganglia or Collateral Ganglia, pass through these to
synapse with Ganglionic Neurons in Adrenal Medulla
E. Parasympathetic (Craniosacral) Division
1. Rest – and – Digest Response
a. Rest
b. Reading
c. Restoration
d. Repair
2. Innervated by Preganglionic Neurons which exit by
a. CN III
b. CN VII
c. CN IX
d. CN X – Majority
e. S2 – S4
3. Ganglia
a. Terminal Ganglia
(1) Oculomotor – Ciliary Ganglion
(2) Facial – Pterygopalatine Ganglion &
Submandibular Ganglion
(3) Glossopharyngeal – Otic Ganglion
b. Intramural Ganglia serve Vagus
4. Pelvic Nerves – Preganglionic Fibers from Sacral
Segments
5. Autonomic Plexuses - Network
a. Vagus Nerve
b. Pelvic Nerves
6. Ganglionic Fibers Release Acetylcholine - Ach
F. Clinical Applications
1. Stress
2. Orthostatic Hypotension
II. Reflexes
A. Reflex Arc
1. Receptor
2. Sensory Neuron
3. Integration Center (Information Processing)
a. Synapse – Simple Reflex
b. Interneurons – Complex Reflex
4. Motor Neuron
5. Effector
B. Types of Reflexes
1. Innate Reflex
2. Cranial Reflex
a. Corneal Reflex
b. Gag Reflex
3. Visceral (Autonomic) Reflex
a. Pupillary Light Reflex
1) Ipsilateral response
b. Consensual Reflex
1) Contralateral response
c. Ciliospinal reflex
d. Salivary reflex
4. Spinal Reflex
5. Somatic Reflex
6. Monosynaptic Reflex
7. Polysynaptic Reflex
a. Crossed Extensor Reflex
8. Stretch Reflexes
a. Patellar, Biceps, Triceps, Calcaneal (Achilles)
1) Muscle Spindles
9. Superficial Reflex
a. Plantar Reflex
1) Babinski’s sign
b. Abdominal Reflex