1. AUTONOMIC NERVOUS SYSTEM BYDR.A.A.OREMOSU DEARTMENT OF ANATOMY CMUL

2. Overview of ANS Pathway for Visceral Motor Output ANS has two antagonistic divisions: 1.Sympathetic 2.Parasympathetic ANS output always involves two neurons between spinal cord (CNS) and effector.

3. Nerve supply of visceral structures Sympathetic- fright or flight response Parasympathetic- recovery from flight/fright response CNS-gnaglion- effector organ Sympathetic also supplies blood vessels of skin, arector pili muscles, arterioles & sweat glands

4. CNS- Ganglion- effector organ

5. Ganglia Lie outside CNS Sympathetic-ganglia are in (a) sympathetic chain & (b) ganglia around large arteries Parasympathetic- ganglia present ON or IN organ which they supply Preganlionic fibres- white rami Postganglionic fibres- gray rami

6. Parasympathetic outflow-craniosacral Sympathetic outflow-thoracolumbar

7. Thoraco lumbar out flow T1- L2(3) Supplies almost all viscera Sympathetic chain 3 cervical, 10-12 thoracic, 4 lummbar, 4-5 sacral, I coccygeal ganglia The 2 chain unite @ ganglion impar in front of coccyx

8. Schematic representation of the ANS

11. Synapsing takes place in ganglia Naming of neurons: neuron #1 preganglionic presynaptic neuron #2 Ganglionic postsynaptic effector Preganglionic fiber (=axon): Always myelinated Postganglionic fiber: Always unmyelinated Fig 17.3 ?

12. Sympathetic Division Thoracolumbar division Preganglionic neurons (cell bodies) located between T1 & L2 of spinal cord Ganglionic neurons (cell bodies) in ganglia near vertebral column Paravertebral ganglia = sympathetic chain ganglia Prevertebral ganglia = collateral ganglia Special case: adrenal medulla Effects of Sympathetic Division?

13. The splanchnic nerves Greater splanchnic(GS)T5-9 Lesser splanchnic(LS)T10-11 Least splanchnic(LeS)T12 Fibres pass through sympathetic chain without relaying End in ganglia GS-coeliac LS-superior mesenteric LeS-may be absent-superior mesenteric

14. Special Case: Adrenal medulla Fig. 17-6 Modified sympathetic ganglion Terminus for neuron #1, stimulates specialized 2nd order neurons with very short axons in adrenal medulla to release NT into blood stream (= hormones) Epinephrine (adrenalin) ~ 80% and norepinephrine (noradrenalin) Endocrine effects are longer lasting than nervous system effects

15. Sympathetic Neuroeffector Junctions Differ from somatic neuromuscular junctions Varicosities

16. Summary of Sympathetic Division A. Neuron #1 is short, neuron #2 is long B. Synapsing occurs in prevertebral chain ganglia or paravertebral collateral ganglia C. Neuron #1 releases Ach, usually neuron #2 releases NE D. Prepares for emergency action, excitatory to many organs, inhibitory to others ( digestive for example) E. Effects very widespread and somewhat persistent

17. Para – Sympathetic Division Craniosacral division Preganglionic neurons (cell bodies) located in brain stem & sacral segments of spinal cord Ganglionic neurons (cell bodies) in ganglia near target organs: Intramural ganglia Effects of parasympathetic division ?

18. Craniosacral outflow Cranial nerves 3,7,9,10 Nucleus, nerve, ganglion & organ supplied Nuclei are Edinger westphal, superior salivatory, inferior salivatory, dorsal motor nucleus of vagus respectively Ganglia ciliary-CN-III Sphenopalatine-CN VII Submandibular- CN VII Otic -CN IX Numerous(thorax,abd.)- CN X

19. PARASYMPATHETIC INNERVATION

20. III-Supply intrinsic eye muscles VII-Glands of nose, mouth & pharynx VII & IX-Salivary glands V-Organ- heart, respiratory system, abdominal viscera

21. Sacral part Nervi eregentes- wandering nerves Supplies pelvic viscera Produces erection in males Relaxes internal urethral sphincter Root value S2,3,4 Stimulation empties bladder

22. INNERVATION OF THE BLADDER

24. Summary of Parasympathetic Division A. Neurons #1 are long, come from the brain stem or sacral spinal cord, run with the spinal or pelvic nerves and produce ACh. B. Neurons #2 are short, produce ACh, and may be either excitory or inhibitory.

25. Anatomy of Dual Innervation Each organ receives innervations from sympathetic and parasympathetic fibers Fibers of both divisions meet & commingle at plexuses to innervate organs close to those centers Names of plexuses derived from locations or organs involved

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