2. sympathetic nervous system
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The document provides an overview of the autonomic nervous system, with a focus on the sympathetic nervous system. It discusses the history and subdivisions of the autonomic nervous system. For the sympathetic nervous system specifically, it describes the development of ganglia from neural crest cells, the pathways of preganglionic and postganglionic neurons, and the locations and branches of sympathetic ganglia along the spinal cord and for different organ systems. It also reviews histology of ganglia, surgical sympathectomy procedures, and Horner's syndrome.
2. sympathetic nervous system
- 1. Autonomic nervous system Sympathetic nervous system Dr Swati Patil 1
- 2. • Autonomic nervous system -History -Introduction -Types :- Sympathetic –Development -Introduction -Course -Types -Applied 2
- 3. Autonomic Nervous System • Self regulating • History: – 1898 - J.N.Langley assigned the term Autonomic Nervous System – 1921 – subdivided ANS into • Sympathetic • Parasympathetic • Enteric 3
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- 5. Autonomic Nervous System • Introduction – Visceral component of nervous system , function closely related to somatic nervous system – Visceral afferent pathways resemble somatic afferent – Peripheral processes – auotonomic ganglia – somatic nerves 5
- 6. Visceral Afferents -Cell bodies –unipolar – present in cranial sensory or dorsal root ganglia -Central processes –with somatic afferents into CNS –establish connections 6
- 7. Visceral Efferent • Visceral efferent pathways in ANS differ from their somatic equivalents • pre-ganglionic neurons: – Somata are located in • visceral efferent nuclei & • in lateral grey columns – axons are • myelinated , • pass to peripheral ganglia • synapse with postganglionic neurons 7
- 8. Visceral Efferents Pre-ganglionic Post-ganglionic ganglion 8
- 9. • Post-ganglionic neurons –axons are unmyelinated , more numerous 9
- 10. Subdivisions of ANS • Sympathetic • Parasympathetic • Enteric 10
- 11. • Sympathetic –mass response - Constriction of cutaneous arteries - Cardiac acceleration - Rise in blood pressure - Contraction of sphincters - Depression of peristalsis • Sympathetic: mobilization & increased metabolism “fight, flight or fright” or “fight, flight or freeze” 11
- 12. Neurotransmitters: • pre-ganglionic neurons of both are cholinergic • post-ganglionic – parasympathetic –cholinergic – sympathetic –nor-adrenergic • principal co-transmitters – ATP , Neuropeptide Y 12
- 13. Sympathetic Nervous System • Development :- -During 5th week, neural crest cells migrate along sides of spinal cord ganglia - dorsolateral to aorta -Some neural crest cells migrate ventral to aorta pre-aortic ganglia – celiac & mesenteric ganglia 13
- 14. • Other neural crest cells migrate to heart, lungs, GIT terminal ganglia • Axons of sympathetic neurones in intermediolateral cell column of thoracolumbar seg of spinal cord pass through ventral root of spinal nerve & white ramus communicans to reach paravertebral ganglia 14
- 15. • Synapse with neurons – ascend / descend in sympathetic trunk • Other presynaptic fibers – pass through paravertebral ganglia without synapsing – splanchnic nerves to viscera • Post synaptic fibres –grey rami from sympathetic ganglion into spinal nerve • Sympathetic trunk – ascending & descending fibres 15
- 16. Sympathetic Trunk • Two ganglionated nerve cords –either side of vertebral column • White & grey rami communicantes • Location –neck ,thorax, abdomen, pelvis 16
- 17. Preganglionic neurones: • Cell bodies of preganglionic sympathetic neurons –in lateral horn • Axons –myelinated ,diam -1.5 - 4 microm • Leave cord in ventral nerve roots – pass into spinal nerves, soon leave in white rami communicants 17
- 18. Behaviour of Preganglionic Fibres • Synapse with neurons in nearest ganglion or may ascend or descend • Fibres terminate in single ganglion or through collateral branches – synapse • Fibres may ascend or descend without synapsing –emerge in branches of sympathetic trunk –synapse in ganglia of autonomic plexus 18
- 19. Postganglionic Neurones of Sympathetic Nervous System • Somata of postganglionic neurons –in ganglia of sympathetic trunk • Axons –unmyelinated, return to spinal nerve through grey ramus just proximal to white ramus & then form dorsal & ventral ramus 19
- 20. Cervical Sympathetic Trunk • B/w Carotid sheath and prevertebral muscles • Internal carotid nerve • Three cervical ganglia – Superior – Middle – Inferior 20
- 21. Superior Cervical Ganglion • Largest ganglion • Lies in front of transverse processes of C2 and C3 vertebrae • Branches – Medial – Lateral 21
- 22. Middle Cervical Ganglion • Smallest of the Cervical ganglion • Lies on the C6 vertebra in front or behind Inf. thyroid artery • Branches – grey rami communicantes – Cardiac branch – Vascular Branch 22
- 23. Stellate Ganglion • Formed by the fusion of C7,C8 andT1 ganglia • Lies b/w neck of 1st Rib and transverse process of C7 vertebra • Branches – Grey rami communicans – Vascular branches 23
- 24. Sympathetic supply – Head and Neck • Preganglionic fibres – T1-T5 segments of Spinal Cord • Ascend in Sympathetic Trunk • Synapse in cervical ganglia 24
- 25. Thoracic Sympathetic Trunk • Comprises of 11 ganglia • Ganglia lie against the heads of ribs • Branches – Grey rami communicans – Pul. And cardiac Plexus – Splanchnic Nerves 25
- 26. Coeliac Plexus • Situated around the origin of coeliac artery • Formed by greater Splanchnic Nerves and Ist lumbar sympathetic nerves • Nerves from the plexus supply abdominal viscera via blood vessels 26
- 27. Lumbar Sympathetic Trunk • Lies retroperitoneally on the anterolat. surface of lumbar vertebrae • Rt side – overlapped by IVC • Lt side – overlapped by Aorta • Branches – Splanchnic nerves – Grey rami communicantes 27
- 28. Hypogastric Plexuses • Superior hypogastric plexus:- -location -formation -branches • Inferior hypogastric plexus :- -location -formation -branches 28
- 29. Adrenal Medulla • Neural crest cells – secretary cells of medulla • Sympathetic supply – preganglionic sympathetic neurons • Secretary cells – postganglionic sympathetic neurons –lack axons or dendrites • Larger secretory cells – secrete adrenaline & NA 29
- 30. Summary 30
- 31. Sympathetic Ganglion Histology : • Connective tissue, ganglion, capsule cells • Nerve cells –multipolar, smaller • Nucleolus –prominent eccentric 31
- 32. Sympathetic Ganglion 32
- 33. Enteric Nervous System • Myenteric (Auerbach’s) plexus & submucosal (Meissner) plexus • Plexus –small enteric ganglia –joined by thin nerves –unmyelinated • Avascular –nutrition by diffusion • Neurones –excitatory & inhibitory • Afferents to ENS -2 types – cholinergic & NA 33
- 34. Pain Afferents • Sensory neurones –pain in thoracic & abdominal organs • Cell bodies –dorsal root ganglia • Peripheral processes – white communicating rami –sympathetic trunk –viscera 34
- 35. • Referred pain –diffuse localization & radiation • Zone of reference of pain from int organ coincides with part of body served by somatic sensory neurons assoc with same segment of spinal cord 35
- 36. Referred Pain • Heart –middle & inferior cervical cardiac nerves, thoracic cardiac branches of left sympathetic chain • Gall bladder –greater splanchnic nerve , diaphragm –phrenic nerve 36
- 37. • Stomach –epigastrium – Rt & Lt greater splanchnic nerves • Duodenal ulcer –AAW – T9 T10 • Appendix –lesser splanchnic nerves –T10 • Pelvis & ureter –least splanchnic nerves –loin & groin 37
- 38. Surgical Sympathectomy • Indications – Peripheral vascular disease –sympathectomy –temporary vasodilatation –development of collaterals – Hyperhidrosis –sympathectomy –permanent relief – Relief of Pain –a) visceral pain –excision / destruction – coeliac ganglia –Ca pancreas, chronic pancreatits – b) causlgia –intense pain 38
- 39. Upper Thoracic and Cervical Sympathectomy • Upper limb -2 & 3 thoracic ganglia with rami & intervening part • 1st thoracic –not removed, preganglionic fibres not arise above T2 (removal – Horner’s syndrome) 39
- 40. Kuntz Nerve • Communicating branch B/w T1and T2 nerves • Receives Grey rami from Stellate and T2 ganglia • Clinical relevance –failure to identify during thoracic sympathectomy 40
- 41. Lumbar Sympathectomy • Gangliectomy -3 & 4 lumbar ganglia & intervening trunk • Removal of LI is harmful – interferes with ejaculation 41
- 42. Horner’s Syndrome • Preganglionic –white ramus of T1 –sympathetic trunk – superior cervical ganglion – postganglionic fibres (ICA) – ophthalmic –nasociliary – long ciliary branches • Damage –vascular lesions of cortex / brainstem, cervical rib, Ca lung, thyroid, oesophagus 42
- 43. Clinical features of Horner’s syndrome: • Miosis –failure dilation – unopposed parasympathetic activity • Partial ptosis –paralysis of LPS • Anhydrosis –lesion of superior cervical ganglion 43
- 44. Central Control of Sympathetic Nervous System • Hypothalamus –controlling &integrating center • Hypothalamus –autonomic nuclei –spinal cord – reticular formation • Posterior & lateral nuclei – noradrenergic response 44
- 45. THANK YOU… 45