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ANS with cardiac innervation
- 1. AUTONOMIC NERVOUS SYSTEM Cardiac Innervation Cardiac Conduction @drsatyajitsaha 1
- 2. Basic Orientation of a Spinal Segment @drsatyajitsaha 2
- 4. The Intermediolateral Cell Column/ Lateral Horn • Unlike the rest of the spinal segments, the segments from T1 – L2/L3 shows a lateral cell mass in the central grey matter. • The cell bodies of the sympathetic connector neuron are present in this lateral horn. • The preganglionic fibers arise from the lateral horn cells and relay in the sympathetic (paravertebral) ganglion or the prevertebral ganglion near the organs. They constitute the efferent fibres@drsatyajitsaha 4
- 5. Difference between Somatic & Autonomic System @drsatyajitsaha 5
- 6. • Somatic Motor Fibres originate from the ventral horn, passes through the anterior root of the spinal nerve, and continue as a part of spinal nerve and supplies the somatic skeletal muscles. • Sympathetic Motor Fibres originate from the Lateral Horn, passes through the anterior root of the spinal nerve, and continue as a part of spinal nerve, relay in the sympathetic ganglion and supplies the visceral smooth muscles, including glands, blood vessels. As it arises from the T1-L3, hence called the THORACOLUMBAR outflow. • Parasympathetic Motor Fibres originate from the Cranial Nerve Nuclei III, VII, IX, X and the S2-S4 spinal segments, enters the parasympathetic ganglion and supplies visceral smooth muscles, and the smooth muscles of eye ball@drsatyajitsaha 6
- 8. The Autonomic Nervous System (ANS) • Division of the peripheral nervous system that supplies smooth muscle and glands. • The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. • Although the ANS is also known as the visceral nervous system, the ANS is only connected with the motor side. • The autonomic nervous system has two branches: • the sympathetic nervous system, • the parasympathetic nervous system @drsatyajitsaha 8
- 9. The Autonomic Nervous System (ANS) • The sympathetic nervous system is often considered the "fight or flight" system. • The parasympathetic nervous system is often considered the "rest and digest" or "feed and breed" system. • In many cases, both of these systems have "opposite" actions where one system activates a physiological response and the other inhibits it. @drsatyajitsaha 9
- 10. The Different Sympathetic Ganglia Nerves, Their Origin, Target Organs @drsatyajitsaha 10
- 11. The Sympathetic Nervous System @drsatyajitsaha 11
- 13. • The ganglia are distinguished as cervical, thoracic, lumbar, and sacral. • Sympathetic ganglia • cervical ganglia (3) • thoracic ganglia (12) • lumbar ganglia (2 or 3) • sacral ganglia • Except in the neck, they closely correspond in number to the vertebrae. The Sympathetic Nervous System @drsatyajitsaha 13
- 14. Ganglion Impar • The pelvic portion of each sympathetic trunk is situated in front of the sacrum, medial to the anterior sacral foramina. It consists of four or five small sacral ganglia, connected together by interganglionic cords, and continuous above with the abdominal portion. • Below, the two pelvic sympathetic trunks converge, and end on the front of the coccyx in a small ganglion, the ganglion impar. @drsatyajitsaha 14
- 15. The Sympathetic Nervous System • Consists of cells with bodies in the lateral grey column from T1 to L2/3. • These cell bodies are "GVE" (general visceral efferent) neurons and are the preganglionic neurons. • Along the length of the sympathetic trunks are ganglia known as ganglia of sympathetic trunk/sympathetic ganglia. • The ganglia are paravertebral in location. @drsatyajitsaha 15
- 16. Ramus Communicantes/Ramus Communicans • Refers to a communicating branch between a spinal nerve and the sympathetic trunk. • Gray ramus communicans (contains less of Myelinated fibres). Connects the sympathetic ganglion to the spinal nerve. • White ramus communicans (contains more of Myelinated fibres). Connects the spinal nerve to the sympathetic ganglion. @drsatyajitsaha 16
- 17. Communicantes / Communicans White Rami Communicans Gray Rami Communicans The white rami communicantes exist only at the levels of the spinal cord where the intermediolateral cell column is present (T1- L2) The grey rami communicantes exist at every level of the spinal cord Carries corresponding preganglionic efferent nerve fibres from the spinal cord to the paravertebral ganglia. Carries postganglionic efferent nerve fibres from the paravertebral ganglia to their destination. Carries afferent nerve fibres from the paravertebral ganglia to the spinal cord. Carries postganglionic efferent nerve fibres from other spinal segment levels. Contains more of Myelinated fibres, hence white in colour Contains less of Myelinated fibres, hence gray in colour @drsatyajitsaha 17
- 18. The Continuation of the Fibre from the Lateral Horn (Preganglionic Fibres) Because it is MYELINATED Why WHITE? @drsatyajitsaha 18
- 19. Further Continuation Because it is UNMYELINATED Why GRAY? SYNAPSE Ach released @drsatyajitsaha 19
- 20. Further Continuation Preganglionic fibres can either ascend or descend along the sympathetic trunk, and relay in a superior or inferior ganglion respectively. Postganglionic fibres will arise from these superior or inferior placed ganglions, and continue in the gray rami communicans of these ganglion and reach target organs. @drsatyajitsaha 20
- 21. Further Continuation Preganglionic fibers pass through the paravertebral sympathetic ganglion without relay & end in the prevertebral sympathetic ganglion. Postganglionic fibres arise from the prevertebral ganglion and relay to the target organ @drsatyajitsaha 21
- 22. Nerve Origin Target Organ Cardiopulmonary Cervical & Upper Thoracic Ganglia Thoracic cavity Thoracic Splanchnic nerves Greater splanchnic nerve T5-T9 or T10 Celiac ganglia stomach, liver, gallbladder, spleen, kidney, small intestine, and the ascending and transverse colon Lesser splanchnic nerve T10-T11 Superior mesenteric ganglia and Aorticorenal ganglia jejunum, ileum, ascending colon and the transverse colon Least splanchnic nerve T12 Renal plexus Vessels, Renal glomerulus, and tubules with branches to the ureteric plexus Lumbar splanchnic nerves L1-2 Inferior mesenteric ganglia and hypogastric plexuses Sacral splanchnic nerves sacral part of sympathetic trunk Inferior hypogastric plexus and ganglia to the pelvic viscera P A R A V E R T E B R A L P R E V E R T E B R A L @drsatyajitsaha 22
- 23. Afferent Sympathetic Pathway Afferent fibers start from the organ, passes through the ganglia without relay, enters the spinal nerve through the white rami communicans and reaches the posterior root ganglion. The central axons then reach the spinal cord via the posterior sensory root.@drsatyajitsaha 23
- 24. Communicantes / Communicans White Rami Communicans Gray Rami Communicans The white rami communicantes exist only at the levels of the spinal cord where the intermediolateral cell column is present (T1- L2) The grey rami communicantes exist at every level of the spinal cord Carries corresponding preganglionic efferent nerve fibres from the spinal cord to the paravertebral ganglia. Carries postganglionic efferent nerve fibres from the paravertebral ganglia to their destination. Carries afferent nerve fibres from the paravertebral ganglia to the spinal cord. Carries postganglionic efferent nerve fibres from other spinal segment levels. Contains more of Myelinated fibres, hence white in colour Contains less of Myelinated fibres, hence gray in colour @drsatyajitsaha 24
- 25. Sympathetic Efferents in a Nutshell @drsatyajitsaha 25
- 26. Sympathetic Innervation of the Adrenal Fibers pass without relay in the Paravertebral or Prevertebral sympathetic ganglia to reach the gland and ends in direct relation with the chromaffin cells in the Adrenal Medulla. (NB Adrenal Medulla develops from the Neural Crest Cells) @drsatyajitsaha 26
- 29. Cranial Parasympathetic Outflow • Cranial outflow is associated with the III, VII, IX, X Cranial Nerves. • The parasympathetic supply of the III, VII & IX is limited in the head neck region only, where as distribution of the X includes heart, lung and the GI system @drsatyajitsaha 29
- 32. Sacral Outflow Sacral outflow arises from the S2-S4 spinal segments. Myelinated fibers leave spinal cord through the anterior nerve roots. These nerves then form the pelvic splanchnic nerves. These preganglionic fibers synapse in peripheral ganglia (hypogastric plexus/presacral plexus/superior hypogastric plexus) close to the organs. Postganglionic fibers are nonmyelinated.@drsatyajitsaha 32
- 33. Difference Between Sympathetic & Parasympathetic System @drsatyajitsaha 33
- 37. Preganglionic Cardiac Sympathetic Innervation Preganglionic fibers arise from T1-T4/T5 spinal segments. Reach corresponding sympathetic thoracic ganglia via white rami communicans. Also reach the cervical sympathetic ganglia running up the sympathetic tract. Preganglionic fibers are cholinergic. @drsatyajitsaha 37
- 38. Postganglionic fibers arise from the superior middle and inferior cervical ganglion and the upper 4-5 thoracic ganglion to reach the heart. Postganglionic fibers are noradrenergic. Increases both the rate & force of contraction. Postganglionic Cardiac Sympathetic Innervation @drsatyajitsaha
- 39. Parasympathetic Cardiac Nerves • Preganglionic fibers arise from the nucleus ambiguus & dorsal nucleus of vagus in the medulla oblongata. • Postganglionic fibers are situated in the cardiac plexus, in the vicinity of SA Node & AV Node. • Both preganglionic & postganglionic are cholinergic. • Decreases the heart rate@drsatyajitsaha 39
- 40. Cardiac Plexus Superficial Cardiac Plexus Cardiac Branch from superior cervical ganglion of the left side Lower cardiac branch of left vagus nerve. Deep Cardiac Plexus Cardiac Br from superior, middle & inferior cervical ganglion & upper 4-5 thoracic ganglia of both sympathetic trunks, except Cardiac Branch from superior cervical ganglion of the left side. Cardiac branch of both vagus & Rec Laryngeal, except lower cardiac branch of left vagus nerve. @drsatyajitsaha 42
- 41. Lateral Horn cells of upper 4-5 thoracic segments Corresponding thoracic ganglia Cervical Ganglia PREGANGLIONIC FIBRES ORIGIN Heart Cardiac & coronary plexuses POSTGANGLIONIC FIBRES Efferent Sympathetic Pathway Functions: 1. Increase the heart rate & cardiac output. 2. Vaso-dilatation of the intramuscular branches of the coronary artery & vasoconstriction of the epicardial arteries@drsatyajitsaha 43
- 42. Dorsal Root ganglia of upper 4-5 thoracic spinal nerves Corresponding thoracic ganglia White Communicans & Posterior spinal root Sensory Cells Heart Afferent Sympathetic Pathway Functions: 1. Convey Painful sensation from heart. Cardiac branches @drsatyajitsaha 44
- 43. Pain of Angina Pectoris @drsatyajitsaha 45
- 44. Site of Block Site of Ischaemia PAIN through sympathetic afferents T1- T5 Gives Rise to Retrosternal Pain Intercostabrachial nr relay pain along the inner margin of the left arm @drsatyajitsaha 46
- 45. Nucleus Ambiguus & Dorsal nucleus of Vagus in the medulla Cardiac Plexus ORIGIN Heart Efferent Parasympathetic Pathway Functions: 1. Decrease the heart rate & cardiac output. @drsatyajitsaha 47
- 48. Cardiac Conduction Parts SA Node :The SA node is located in the wall (myocardium) of the right atrium, laterally to the entrance of the superior vena cava in a region called the sinus venarum. AV Node : The AV node lies at the lower back section of the inter-atrial septum near the opening of the coronary sinus @drsatyajitsaha 50
- 50. Blood Supply to Cardiac Conducting System @drsatyajitsaha 52