Content:
Introduction 0:00
Ganglion and Nucleus 01:41
Paravertebral and Prevertebral Ganglia 02:13
Neurotransmitters 03:25
Sympathetic Preganglionic Neurons 06:22
Sympathetic Postganglionic Neurons 07:45
General Structures Summary 08:25
Sympathetic Trunk 09:17
Innervation of Head/Neck/Thorax 10:50
Innervation of Abdominal Viscera 18:48
Autonomic Plexuses 25:50
Quiz 27:15
Sympathetic Nervous System; A system of fight or flight, that increases energy expenditure and catabolism. It increases heart rate and myocardial contractility, dilates bronchi, increases blood pressure and indirectly increases blood glucose and lipid levels.
It's a part of the autonomic nervous system, which is under the motor division of peripheral nervous system.
General Structures and terms:
- Group of cell bodies in CNS - Nucleus
- Group of cell bodies outside CNS - Ganglion
- Paravertebral ganglia
- Prevertebral ganglia
- Presynaptic neuron is a cholinergic neuron (Ach binds to nicotinic receptors, allowing an influx of cations)
- Postganglionic neurons are primarily adrenergic neurons (norepinephrine and epinephrine binds to adrenergic receptors, activating g-protein)
Sympathetic Preganglionic Neurons:
- Arise from intermediolateral nuclei (C8/T1-L2/L3)
- White rami communicantes (rami communicantes albi) myelinated axons from the intermediolateral nucleus that enter the sympathetic trunk. Then:
○ May terminate in the sympathetic ganglion at the same level
○ May travel up or down the sympathetic trunk to terminate in ganglia at a higher or lower level
○ May leave the sympathetic trunk to terminate in a peripheral ganglion
Sympathetic Postganglionic neurons:
- Grey rami communicantes (rami communicantes grisei)
○ Join spinal nerves and innervate cutaneous glands and erector pili muscle.
- Vascular branches
○ Travel with arteries to provide sympathetic innervation of organs and limbs
- Visceral branches and splanchnic nerves (rami viscerales, nervi splanchnici)
○ travel towards the organs
Sympathetic Trunk:
- Cervical ganglia (ganglia cervicalia)
○ Superior cervical ganglion
○ Middle cervical ganglion
○ Inferior cervical ganglion aka Cervicothoracic, stellate ganglion
- Thoracic ganglia (ganglia thoracica)
- Lumbar ganglia (ganglia lumbalia)
- Sacral ganglia (ganglia sacralia)
- Coccygeal ganglia, often fused to form ganglion impar (unpaired).
Innervation of Head, Neck and Thorax:
- Superior Cervical postganglionic fibers:
○ Grey rami communicans join the first 4 cervical nerves
○ Internal carotid nerve (nervus caroticus internus)
○ External carotid nerves (nervi carotici externi)
○ Laryngopharyngeal branches (rami laryngopharyngei)
○ Superior cervical cardiac nerve (nervus cardiacus cervicalis superior)
- Middle cervical postganglionic fibers:
○ Grey rami communicans join 5th and 6th cervical nerves
○ Visceral branches (rami viscerales)
○ Middle cervical cardiac nerve (nervus cardiacus cervicalis medius)
- Inferior cervical postganglionic fibers
○ Grey rami communicans join C7, C8 and T1
○ Vertebral nerve (nervus vertebralis)
○ Inferior cervical cardiac nerve (nervus cardiacus cervicalis inferior)
- Thoracic ganglia
○ Gray rami communicans join intercostal nerves
○ Thoracic cardiac nerves (nervi cardiaci thoracici) form Cardiac plexus to increase contractility and heart rate
○ Pulmonary branches (rami pulmonales) form pulmonary plexus to cause bronchodilation
○ Oesophageal branches (rami oesophagei) form esophageal plexus to decrease peristalsis
Innervation of abdomen and pelvis:
- Preganglionic fibers go towards prevertebral ganglia
○ Greater splanchnic nerve (nervus splanchnicus major) travel towards celiac ganglia (ganglion ciliare), postganglionic fibers go through plexuses and reach proximal organs in abdomen
○ Preganglionic fibers of greater splanchnic nerve go directly to renal medulla
○ Lesser splanchnic nerve (nervus splanchnicus minor) towards superior mesenteric ganglion for the duodenum, small intestine, large intestine until proximal 2/3.
○ Least splanchnic nerve (nervus splanchnicus imus) go towards the aorticorenal ganglion then towards the kidneys and the ureter
○ Lumbar splanchnic nerves (nervi splanchnici lumbales) go towards the inferior mesenteric ganglia, then towards rest of large intestine, urinary bladder and genitalia
○ Sacral splanchnic nerves (nervi splanchnici sacrales)
Sources:
- Singh, I. (2017). Human neuroanatomy (10th ed)
- Kozlowski, T. (2017). Memorix Anatomy 2nd ed
- Gray's Anatomy: The Anatomical Basis of Clinical Practice (42th ed.)
- Sinnatamby, Chummy S. (2011). Last's Anatomy (12th ed.)
- Yan FL, Zhang JH. Role of the sympathetic nervous system and spleen in experimental stroke-induced immunodepression
Programs:
- Complete Anatomy: 3d4medical.com/
- Biorender: www.biorender.com/
- PowerPoint
- Camtasia 2023
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