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AUTONOMIC NERVOUS SYSTEM

AUTONOMIC NERVOUS SYSTEM. BY DR.A.A.OREMOSU DEARTMENT OF ANATOMY CMUL. Overview of ANS. Pathway for Visceral Motor Output ANS has two antagonistic divisions: Sympathetic Parasympathetic ANS output always involves two neurons between spinal cord (CNS) and effector.

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AUTONOMIC NERVOUS SYSTEM

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  1. AUTONOMIC NERVOUS SYSTEM BY DR.A.A.OREMOSU DEARTMENT OF ANATOMY CMUL

  2. Overview of ANS Pathway for Visceral Motor Output ANS has two antagonistic divisions: • Sympathetic • 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-craniosacralSympathetic 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

  9. Synapsing takes place in ganglia Naming of neurons: ? Fig 17.3

  10. 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?

  11. 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

  12. 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

  13. Sympathetic Neuroeffector Junctions Differ from somatic neuromuscular junctions Varicosities

  14. 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

  15. Para – SympatheticDivision 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 ?

  16. 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

  17. PARASYMPATHETIC INNERVATION

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

  19. 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

  20. INNERVATION OF THE BLADDER

  21. 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.

  22. 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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