Lecture 18 Flashcards
What are the 2 divisions of the autonomic nervous system?
Sympathetic (T1-L2) and Parasympathetic (CN’s 3, 7, 9, 10 and S2-4)
Preganglionic Neurons
Always myelinated; synapses with postganglionic neuron; utilizes acetylcholine
Postganglionic Neurons
Originates from ganglion; never myelinated; generally utilizes norepinephrine
Parasympathetic Nerves
Synapse on microscopic ganglion cells embedded in walls of target organs; primarily responsible for maintaining and coordinating gut function (secretion of fluids and peristaltic contractions)
Sympathetic Nerves
Synapse on cells located in large, visible ganglia located in dorsal wall of coelom, typically anterior to abdominal aorta; involved in responses related to anger, fear, and anxiety; inhibits digestive fluid secretion, inhibits peristalsis, closes involuntary sphincters, constricts blood flow to gut
Cervical Ganglia
Superior, middle, inferior; lies against neck of ribs and costovertebral junctions
Thoracic Ganglia Pairs
12 pairs of ganglia; first one fused with inferior cervical ganglion; referred to as stellate ganglion collectively
Cardiopulmonary Splanchnic Nerves
Travel on their own and do not accompany other nerves or vessels; function in coronary artery dilation, increase heart rate, bronchodilation
Sympathetic Supply to Abdominal Organs
Preganglionic fibers do not synapse in paravertebral ganglia but pass medially to synapse on ganglion cells located around the aorta; postganglionic fibers travel from the preaortic ganglia to their target organs by following the arterial branches
Thoracic Sympathetic Chain
Preganglionic sympathetic supply to the thoracic viscera are from T1-5; postganglionics are from superior, middle, and inferior cervical ganglia and T1-5 paravertebral ganglia
Splanchnic Nerves
Composed of preganglionic fibers and visceral sensory fibers; supply abdominal viscera and synapse in prevertebral ganglia
Greater Splanchnic Nerve
T5-9; synapses in celiac ganglion; also consists of celiac plexus and hepatic plexus
Lesser Splanchnic Nerve
T10-11; synapses in the superior mesenteric ganglion
Least Splanchnic Nerve
T12; synapses in the aorticorenal ganglion
Celiac Ganglia
Prevertebral; superior to celiac trunk
Celiac Plexus (cerebrum abdominale, solar plexus)
Sympathetic to: stomach, duodenum, ileum, jejunum, spleen, pancreas, gall bladder, kidneys, suprarenal glands; also carries pregnaglionic fibers of vagus nerve (parasympathetic fibers)
Hepatic Plexus
Sympathetic to liver
Superior Mesenteric Ganglia
Prevertebral; superior to plexus; sympathetic to: duodenum, ileum, jejunum, cecum, vermiform appendix, ascending colon, transverse colon, pancreas
Aoritcorenal Ganglia
Prevertebral; sympathetic to: kidneys, suprarenal glands
Abdomincal Sympathetic Trunk
Paravertebral; continuous with thoracic sympathetic trunk; lumbar splanchnic nerves (T11-L2); inferior mesenteric ganglion (prevertebral); superior and inferior hypogastric plexuses, which has sympathetic innervation to: descending colon and sigmoid colon, as well as rectus and pelvic structures
Vagus Nerve
Cranial nerve X; major parasympathetic supply to thoracic and abdominal viscera
Course of the Vagus Nerve
Parallel to esophagus (innervates esophagus); left vagus nerve becomes anterior vagal trunk, right vagus nerve becomes posterior vagal trunk; passes posterior to root of lung on each side, pierces diaphragm with esophagus, becomes gastric nerve; supplies viscera in thoracic cavity and supplies viscera in the abdominal cavity to the left colic flexure
Left Recurrent Laryngeal Nerve from Left Vagus
Hooks around arc of aorta to left ligamentum arteriosum
Right Recurrent Laryngeal Nerve from Right Vagus
Hooks around subclavian artery and therefore arises in the neck and not the thorax
