Relevant anatomy of sympathetic ganglia

sympathetic chain anatomy for medical students and resident doctors and paramedics

1. RELEVANT ANATOMY OF THE SYMPATHETIC GANGLIA BY DR GEORGE OWUSU

2. OUTLINE INTRODUCTION EMBRYOLOGY OF THE SYMPATHETIC GANGLIA GROSS ANATOMY OF THE SYMPATHETIC GANGLIA SYMPATHETIC CHAIN STRUCTURE PARTS COLLATERAL (PRE-AORTIC) GANGLIA CONCLUSION

3. INTRODUCTION The sympathetic nervous system is part of the autonomic nervous system, responsible for certain involuntary control of the cardiac and smooth muscles and glands. Relay or synapse at certain points on their course forming sympathetic ganglia. Connect with each other via nerve strands forming the sympathetic trunk, collateral ganglia (pre-aortic ganglia) and plexuses. In as much as the sympathetic network of cells serve vital bodily functions, it is pertinent to understand that derangement in some ganglionic cells could lead to certain pathological anomalies such as Neuroblastoma

4. EMBRYOLOGY OF THE SYMPATHETIC GANGLIA In the fifth week, neural crest cells of the thoracic region arising from the mantle layer (which will go ahead to form neuroblast ), migrate on each side of the spinal cord, towards the region immediately behind the dorsal aorta. They form a bilateral chain of sequentially arranged sympathetic ganglia interconnected by longitudinal nerve fibers on each side of the vertebral column .

5. EMBRYOLOGY OF THE SYMPATHETIC GANGLIA From their position in the thorax, neuroblast migrate towards the cervical and lumbo-sacral regions, extending the sympathetic chains to their full length. Some neuroblast migrate in front of the aorta to form the pre-aortic ganglia Other sympathetic cells migrate to organs such as the heart, lungs and gastro-intestinal tract where the give rise to sympathetic organ plexuses

6. EMBRYOLOGY OF THE SYMPATHETIC GANGLIA Initially the ganglia are segmentally arranged, however this arrangement is later obscured by fusion of the ganglia especially in the cervical region. Once the sympathetic chains have been established, nerve fibers originating in the viscero-efferent column (intermediate horn) of the thoracolumbar segments of the penetrate the ganglia of the chain.

7. GROSS ANATOMY SYMPATHETIC CHAIN: A pair of ganglionated longitudinal cords of the sympathetic nervous system on both side of the vertebral column EXTENT: It extends bilaterally from the base of the skull to the coccyx where the converge with each other forming the ganglion impar

8. GROSS ANATOMY PARTS OF THE SYMPATHETIC CHAIN: The sympathetic chain is divided into four parts: Cervical Thoracic Abdominal (lumbar) Pelvic (sacral)

9. GROSS ANATOMY CERVICAL PART: This extends from the base of the skull to the first rib. Lies in the neck embedded in the deep fascia between the carotid sheath anteriorly and longus coli and longus capitis muscles posteriorly. Made up of three ganglia (superior, middle and inferior cervical ganglia)

10. GROSS ANATOMY THORACIC PART: The chain runs downwards on the heads of the ribs and leaves the thorax on the side of the body of the 12 th thoracic vertebra behind the medial arcuate ligament. It is made up of eleven segmentally arranged ganglia (following formation of the stellate ganglion)

11. GROSS ANATOMY ABDOMINAL (LUMBAR) PART : The sympathetic trunk enters the abdomen by passing behind the medial arcuate ligament, on the psoas major. Runs along the medial margin of the psoas muscle to the pelvic brim. The lumbar part of the sympathetic trunk contains about four ganglia.

12. GROSS ANATOMY ABDOMINAL (LUMBAR) PART: Branches: Gray rami communicans to all lumbar spinal nerves. Lumbar splanchnic nerves (pre-ganglionic) arising from all ganglia Those from the 1st and 2nd ganglia supply the pre-aortic ganglia The 3rd and 4th splanchnic nerves form the superior hypogastric plexus in front of the L5 vetebra and sacral promontory The superior hypogastric plexus sends fibers (hypogastric nerve) to join the pelvic inferior hypogastric plexus.

13. GROSS ANATOMY PELVIC (SACRAL) PART : The sympathetic chain enters the pelvis crossing the pelvic brim behind the common iliac vessels Extends down the concavity of the sacrum on the medial margins of the anterior sacral foramina to converge in front of the coccyx; uniting to form the ganglion impar . branches: Somatic branches to all sacral nerves Pelvic visceral branches which join the inferior hypogastric plexus

14. GROSS ANATOMY COLLATERAL (PRE-AORTIC) GANGLIA: This comprises of clusters of ganglia and plexuses in front of the aorta, formed around its branches. The major ganglia include the: Coeliac Superior mesenteric Aorticorenal Inferior mesenteric

15. GROSS ANATOMY COLLATERAL (PRE-AORTIC) GANGLIA: The supply the gut and abdominal viscera via plexuses which accompany their blood supply. The greater and lesser splanchnic nerves pierce the crura of the diaphragm and enter the large coeliac ganglia which lie in front of the crura and superior mesenteric ganglia which connects with other ganglia via the inter mesenteric plexuses

16. GROSS ANATOMY COLLATERAL (PRE-AORTIC) GANGLIA: Coeliac ganglia: supplies the liver, gall bladder, pancreas, gonads and foregut (pre-ganglionic fiber from the greater splanchnic nerve continues to supply the medulla of the adrenal gland). Superior mesenteric ganglion: supplies the mid gut Aorticorenal ganglia: supplies the kidneys Inferior mesenteric ganglia: supplies the hindgut.

17. CONCLUSION The sympathetic nervous system is enabled to carry out its vital activities through a well articulated network of nerves, ganglia and plexuses reaching every part of the body. However a good knowledge and understanding of the embryological origin and structure of the sympathetic ganglion is key in our understanding of certain pathological anomalies such as Neuroblastoma and other neurocristopathies.

18. THANK YOU!!!!

19. REFERENCES Chummy sinnatamby . Last’s anatomy 12 th edition 2011. 278:280 Keith Moore et al. clinically oriented anatomy 6 th edition 2010. 318:319 Frank Netter. Atlas of human anatomy 6 th edition 2014 Sadler T. W. et al. langmans medical embryology 9 th edition 474:477