ANS FUNCTIONS AND CLINICAL EVALUATION.pptx

Autonomic nervous system

1. ANS FUNCTIONS AND CLINICAL EVALUATION

2. Sympathetic division Thoracolumbar division- Preganglionic neurons originate from the thoracic and lumbar levels of the spinal cord (T1-L2). Sympathetic ganglia: Sympathetic trunk (vertebral chain) ganglia. Prevertebral (collateral) ganglia: celiac, superior mesenteric, inferior mesenteric, aorticorenal and renal.

3. Sympathetic nervous system The preganglionic neurons of the sympathetic division originate in the intermediolateral cell column of the spinal gray matter, from the eighth cervical to the second lumbar segments. Axons of the nerve fibers originating in the intermediolateral column are of small caliber and are myelinated ; form the white communicating rami . These preganglionic fibers synapse with the cell bodies of the postganglionic neurons, which are collected into two large ganglionated chains or cords, one on each side of the vertebral column ( paravertebral ganglia), and several single prevertebral ganglia.

4. Most of the postganglionic fibers pass via gray communicating rami to spinal nerves of T5 to L2; they supply blood vessels, sweat glands, and hair follicles. The postganglionic fibers of the prevertebral ganglia (located in the posterior abdomen rather than paravertebrally ) form the hypogastric , splanchnic , and mesenteric plexuses, which innervate the glands, smooth muscle, and blood vessels of the abdominal and pelvic viscera

5. Post ganglionic neurons An axon may synapse with postganglionic neurons in the ganglion it first reaches or Sympathetic chains or An axon may continue, without synapsing , through the sympathetic trunk ganglion to end at a prevertebral ganglion and synapse with postganglionic neurons there or An axon may pass through the sympathetic trunk ganglion and a prevertebral ganglion and then to the adrenal medulla.

6. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Trunk Ganglia

7. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to Periphery Figure 15.9

8. S 8

9. PARASYMPATHETIC DIVISION

10. Cranial outflow Preganglionic fibers run via: Oculomotor nerve (III) Facial nerve (VII) Glossopharyngeal nerve (IX) Vagus nerve (X) Cell bodies located in cranial nerve nuclei in the brain stem

11. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Outflow via the Vagus Nerve (X) Fibers innervate visceral organs of the thorax and most of the abdomen Stimulates - digestion, reduction in heart rate and blood pressure Preganglionic cell bodies Located in dorsal motor nucleus in the medulla Ganglionic neurons Confined within the walls of organs being innervated

12. Sacral outflow Emerges from S 2 -S 4 Innervates organs of the pelvis and lower abdomen Preganglionic cell bodies Located in visceral motor region of spinal gray matter Form splanchnic nerves

13. Parasympathetic ganglia: terminal ganglia. Presynaptic neuron usually synapses with 4-5 postsynaptic neurons all of which supply a single visceral effector .

14. Structure of the Parasympathetic Division 14

15. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The Parasympathetic Division