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![Visceral Afferents and Referred Pain
Somatic sensation:
• conscious, sharp, well-localized
• touch, pain, temperature, pressure, proprioception
Visceral sensation:
• often unconscious; if conscious: dull, poorly-localized
• distension, blood gas, blood pressure, cramping, irritants
dorsal root ganglion
Visceral sensory nerves [GVA]
• run with sympathetic &
parasympathetic nerves
• cell bodies in dorsal root ganglion
• nerve ending in viscera](https://image.slidesharecdn.com/2020thesympatetnervoussystemnew-201119173908/85/The-Sympathetic-Nervous-System-27-320.jpg)
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The Sympathetic Nervous System
- 1. The Sympathetic Nervous System THEVEGETATIVE NERVOUS SYSTEM THE PARASYMPATHETIC PART
- 2. Sympathetic Nervous System 1.lateral gray horns (T1-L2) 2. thoracolumbar outflow 3. ganglia a. sympathetic trunk (paravertebral) b. Prevertebral (collateral) 4. preganglionic axons short 5. postganglionic axons long
- 3. The paired sympathetictrunk runs from the external cranial base down to the coccyx. It comprises 20-25 ganglia of sympathetic trunk Upon reaching the coccyx, the trunks merge into a single ganglion impar The ganglia of the sympathetic trunk contain the peripheral efferent neurons of the sympathetic part ( multipolar neurons).
- 4. spinal nerve dorsal ramus ventral ramus gray ramus communicans whiteramus communicans sympathetic ganglion intermediolateral gray column Structure of spinal nerves: Sympathetic pathways
- 5. Sympathetic System: PostganglionicCell Bodies Paravertebral ganglia Prevertebral ganglia • celiac ganglion • sup. mesent. g. • inf. mesent. g. aorta sympathetic trunk (chain) 1. Paravertebral ganglia • Located along sides of vertebrae • United by preganglionics into Sympathetic Trunk • Preganglionic neurons are thoracolumbar (T1–L2/L3) but postganglionic neurons are cervical to coccyx • Some preganglionics ascend or descend in trunk synapse at same level ascend to synapse at higher level descend to synapse at lower level Moore’s COA6 2010
- 6. Sympathetic System: PostganglionicCell Bodies Paravertebral ganglia Prevertebral ganglia • celiac ganglion • sup. mesent. g. • inf. mesent. g. aorta sympathetic trunk (chain) 2. Prevertebral (preaortic) ganglia • Located anterior to abdominal aorta, in plexuses surrounding its major branches • Preganglionics reach prevertebral ganglia via abdominopelvic splanchnic nerves Moore’s COA6 2010 abdominopelvic splanchnic nerve
- 7. Sympathetic System: Summary Moore’sCOA6 2010 T1 L2 somatic tissues (body wall, limbs) visceral tissues (organs) postganglionics via 31 spinal nerves to somatic tissues of neck, body wall, and limbs sympathetic trunk prevertebral ganglia Cardiopulmonary Splanchnics: postganglionic fibers to thoracic viscera Abdominopelvic Splanchnics: preganglionic fibers to prevertebral ganglia, postganglionic fibers to abdominopelvic viscera
- 10. Moore’s COA6 2010 somatictissues (body wall, limbs) visceral tissues (organs) Sympathetic System: Preganglionic Cell Bodies • Preganglionic cell bodies in intermediolateral gray • T1 – L2/L3 • Somatotopic organization intermediolateral gray columns lateral horn T1 – L2/L3
- 11. Superior Cervical Ganglion Thesuperior cervical ganglion is located posteriorly to the internal carotid artery, and anterior to the C1-4 vertebrae. Several important post-ganglionic nerves originate from here: Internal carotid nerve – hitch-hikes along the internal carotid artery, forming a network of nerves. Branches from the internal carotid plexus innervate structures in the eye, the pterygopalatine artery and the internal carotid artery itself. External carotid nerve – hitch-hikes along the common and external carotid arteries, forming a network of nerves. It innervates the smooth muscle of the arteries. Nerve to pharyngeal plexus – combines with branches from the vagus and glossopharyngeal nerves to form the pharyngeal plexus. Superior cardiac branch – contributes to the cardiac plexus in the thorax. Gray rami communicantes – join four upper cervical spinal nerves C1-C4.
- 14. Middle Cervical Ganglion Itlies at the level of the transverse processes of the C V and C VI vertebrae. It is connected to the superior cervical ganglion with one interganglionic branch and with the inferior cervical ganglion with two interganglionic branches. They form the ansa subclavia ( loop of Vieussens ) it gives some branches as follow – a) The grey communicating branches to the C IV – C VI spinal nerves. b) The common carotid nerve forms the same plexus c) The middle cervical cardiac nerve takes part of the formation the deep part of the extraorganic cardiac plexus.
- 15. Inferior Cervical Ganglion Theinferior cervical ganglion is situated anteriorly to the C7 vertebra. It is occasionally fused with the first thoracic vertebrae, forming the cervicothoracic ganglion. There are three post- ganglionic fibres that arise from this ganglion: •Gray rami communicantes – distributes sympathetic fibres to the anterior rami of C7, C8 and T1. •Branches to the subclavian and vertebral arteries – These innervate the smooth muscle present in the arteries. •Inferior cardiac nerve – contributes to the cardiac plexus in the thorax.
- 17. Ganglia Vertebral LevelArteries Involved Effector Organ(s) Superior cervical ganglion C1-C4 Common, external and internal carotid arteries •Eyeball •Face •Nasal glands •Pharynx •Glands of the palate and nasal cavity •Salivatory glands •Lacrimal glands •Sweat glands •Pineal gland •Dilator pupillae •Superior tarsal muscle •Carotid body •Heart •Arterial smooth muscle Middle cervical ganglion C6 Inferior thyroid artery •Larynx •Trachea •Pharynx •Upper oesophagus •Heart •Arterial smooth muscle Inferior cervical ganglion C7 Vertebral and subclavian arteries •Heart •Arterial smooth muscle Summary Table •
- 18. The thoracic partof sympathetic trunk comprises 10 to 12 thoracic ganglia situated on the heads of ribs below the parietal pleura. Posteriorly one can distinguish the posterior intercostal arteries and veins. The thoracic ganglia give the following branches: 1. the grey communicating branches pass to the corresponding intercostal branches 2. Thoracic cardiac branches 3. The visceral branches which take part in innervation of the vessels and viscera of the thoracic cavity – • Oesophageal branches • Bronchial branches • Pulmonary branches 4. The greater splanchnic nerve 5. The lesser splanchnic nerve 6, The lowest splanchnic nerve
- 19. The lumbar gangliaare situated on the anterolateral surfaces of the lumbar vertebral bodies. Each lumbar ganglion has two types of branches- 1. The grey communicating branches – to the lumbar nerves. 2. The lumbar splanchnic nerves which contain mostly preganglionic fibers and go to the coeliac autonomic plexuses of the abdominal cavity. The sacral or pelvic part of the sympathetic trunk is situated on the pelvic surface of the sacrum medial to the sacral foramina. They give some branches- 1. The grey communicating branches – to the sacral nerves. 2. The sacral splanchnic nerves – which contain mostly preganglionic fibres and proceed to the superior and inferior hypogastric plexuses.
- 20. Vegetative plexuses ofthe abdominal aorta The largest vegetative plexus is the abdominal aortic plexus which is located on the aorta and consists of some primary plexuses. They are- The coeliac plexus The superior mesenteric plexus The intermesenteric plexus The inferior mesenteric plexus The superior hypogastric plexus
- 21. The coeliac plexus– it is unpaired and lies at the origin of the coeliac artery . There are two semilunar coeliac ganglia ( or one horse shoe shape ) within the coeliac plexus. The coeliac plexus receives branches from the – 1. Greater and lesser splanchnic nerves ( sympathetic) 2. Thoracic and lumbar spinal nerves ( sensory) 3. Phrenic nerve ( sensory) 4. Vagus nerve ( parasympathetic ) A great number of nerve branches arise from the celiac plexus and run in all directions to form secondary plexuses. They are- The phrenic plexus The hepatic plexus The splenic plexus The gastric plexus The pancreatic plexus
- 22. The superior mesentericplexus Is situated at the origin of the superior mesenteric artery. It is a complex of the ; a) Superior mesenteric ganglion b) Greater and lesser splanchnic nerves and upper lumbar splanchnic nerves (sympathetic) c) Lumbar spinal nerves (sensory) d) Vagus nerve (parasympathetic) The secondary plexuses of the superior mesenteric plexus are- The pancreatic plexus The jejunal and ileal plexus The caecal plexus The right colic plexus The middle colic plexus
- 23. The intermesenteric plexusis situated between the superior and inferior mesenteric plexuses . It is formed by – a) Aorticorenal ganglia b) Greater and lesser splanchnic nerves and lumbar splanchnic nerves ( sympathetic ) c) Lumbar spinal nerves ( sensory) d) Vagus nerve ( parasympathetic ) The secondary plexuses of the intermesenteric plexus are- The renal plexus The suprarenal plexus The testicular or ovarian plexuses
- 24. The inferior mesentericplexus lies at the root of the inferior mesenteric artery . It is formed by- 1. Inferior mesenteric ganglion 2. Greater and lesser splanchnic nerves and lumbar and sacral splanchnic nerves (sympathetic ) 3. Lumbar spinal nerves (sensory) 4. The pelvic splanchnic nerves (parasympathetic) The secondary plexuses of the inferior mesenteric plexus are- The superior rectal plexus The left colic plexus The sigmoid plexus
- 25. The superior hypogastric plexuslies below the bifurcation of the abdominal aorta. It is formed by – 1. Superior hypogastric ganglion 2. lumbar and sacral splanchnic nerves (sympathetic ) 3. Sacral spinal nerves (sensory) 4. The pelvic splanchnic nerves (parasympathetic) The superior hypogastric plexus does not give secondary plexus.
- 26. THE PELVIC PLEXUS Theinferior hypogastric plexus is paired and the continuation of the unpaired superior hypogastric plexus . It lies on the posterior wall of the lesser pelvis. The secondary plexuses of the inferior hypogastric plexus are- • The rectal plexus • The vesical plexus • The prostatic plexus • The uterovaginal plexus • The plexus of the vas deferens
- 27. Visceral Afferents andReferred Pain Somatic sensation: • conscious, sharp, well-localized • touch, pain, temperature, pressure, proprioception Visceral sensation: • often unconscious; if conscious: dull, poorly-localized • distension, blood gas, blood pressure, cramping, irritants dorsal root ganglion Visceral sensory nerves [GVA] • run with sympathetic & parasympathetic nerves • cell bodies in dorsal root ganglion • nerve ending in viscera
- 29.