Sympathetic Nervous System Pathways PDF

Sympathetic nervous system pathways Skin Pathway: Spinal Cord (T1-L2) → Sympathetic Trunk/Paravertebral Ganglia (all levels)→ Peripheral Nerves → Skin (sweat glands, arrector pili muscles, and blood vessels) Spinal Cord (T1-L2) → Sympathetic Trunk (all levels) Fibers enter trunk white ramus (T1...

Sympathetic nervous system pathways Skin Pathway: Spinal Cord (T1-L2) → Sympathetic Trunk/Paravertebral Ganglia (all levels)→ Peripheral Nerves → Skin (sweat glands, arrector pili muscles, and blood vessels) Spinal Cord (T1-L2) → Sympathetic Trunk (all levels) Fibers enter trunk white ramus (T1-L2 levels only), may stay at level or travel superior/inferior in sympathetic trunk to reach target spinal levels Synapses onto postganglionic neuron in paravertebral ganglia prior to leaving sympathetic trunk via gray ramus Travel in Peripheral Nerves → Innervate Dermatomes of Skin (sweat glands, arrector pili muscles, and blood vessels) Organs of the Head & Neck: Pathway: Spinal Cord (T1-T5) → Sympathetic Trunk /Paravertebral Ganglia (superior cervical ganglia)→ Cephalic Arterial Branch (splanchnic nerve)→ Organs of the Head & Neck (ciliary muscle, dilator pupillae, sensory from carotid sinus) Spinal Cord (T1-T5) → Sympathetic Trunk Fibers enter trunk via white ramus, travel superiorly on sympathetic trunk to superior cervical ganglia, synapse on postganglionic neurons prior to exiting via cephalic arterial branch → Innervate Organs of the Head & Neck (ciliary muscle, dilator pupillae, sensory from carotid sinus) Thoracic Organs: Pathway: Spinal Cord (T1-T5) → Sympathetic Trunk /Paravertebral Ganglia (superior cervical ganglia to T5) → Cardiopulmonary Splanchnic Nerves → Thoracic Organs Spinal Cord (T1-T5) → Sympathetic Trunk Fibers enter sympathetic trunk, synapse in paravertebral ganglia from Superior Cervical Ganglion to T5 → Heart: Some fibers travel superiorly to superior, middle, or inferior cervical ganglia, synapse on postganglionic neurons, leave via trunk cardiopulmonary splanchnic nerves AND Fibers enter trunk, synapse on postganglionic neurons at level immediately (T-T5), leave trunk via cardiopulmonary splanchnic nerves → Lungs: Fibers enter trunk, synapse on postganglionic neurons at level immediately (T-T5), leave trunk via cardiopulmonary splanchnic nerves Abdominopelvic Organs: Pathway: Spinal Cord (T5-L2) → Sympathetic Trunk → Splanchnic Nerves (e.g., Greater, Lesser, Least Thoracic and Lumbar) → Prevertebral Ganglia (e.g., Celiac, Superior Mesenteric Ganglia) →Abdominopelvic Organs. Spinal Cord (T5-L2) → Sympathetic Trunk Enter trunk via white rami, may travel inferior or leave trunk immediately as splanchnic nerves Splanchnic Nerves (sympathetic trunk levels)→ Prevertebral Ganglia → Target Organs Greater thoracic (T5-T9)→Celiac paravertebral ganglion→Stomach, liver, gallbladder, spleen, pancreas  Lesser thoracic (T10-T11)→Aorticorenal paravertebral ganglion→kidney and suprarenal gland Least thoracic (T12)→Superior mesenteric paravertebral ganglion→ proximal GI tract Lumbar (L1-L2/3)→ Inferior mesenteric ganglia→ distal GI tract, bladder, reproductive organs Sacral splanchnic nerves → pelvic organs