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Parasympathetic Nervous System
Typically the PSNS is involved in: • Salivation • Lacrimation • Urination • Digestion • Defecation The ANS, regulates the body's visceral organs via the innervation of three kinds of tissues: • Smooth Muscle • Cardiac Muscle • Glands. • The PSNS is found in Cranial and Sacral regions of the Spinal Cord and is therefore often described as having a Cranio-Sacral outflow. The SNS for similar reasons is described as Thoraco-Lumbar in outflow. T1 to L2 In the cranium the PSNS originates from the following cranial Nerves: • Third Cranial Nerve - Oculomotor • Seventh Cranial Nerve - Facial • Ninth Cranial Nerve - Glossopharyngeal • Tenth Cranial Nerve - Vagus In the Sacral Region the PSNS is derived from spinal nerves • S2 • S3 • S4 Referred to as the Pelvic Splanchnics. PSNS In The Cranial Nerves. Oculomotor Innervates the orbit to control the Ciliary Muscle which is responsible for accommodation and the Sphincter Pupillae Muscle which is responsible for miosis or constriction of the pupil in response to light or accommodation. Facial Parasympathetic function within the Facial Nerve controls secretion of the Sublingual and Submandibular Salivary Glands, the Lacrimal Gland, and the glands associated with the Nasal Cavity. Glossopharyngeal. Parasympathetic fibers innervate the Parotid Gland. Vagus Vagus gives no Parasympathetic input to the cranium, but several Parasympathetic Nerves leave Vagus as it enters the Thorax. • Recurrent Laryngeal Nerve, which becomes the Inferior Laryngeal Nerve. Each Recurrent Laryngeal Nerve supplies the Trachea and the oesophagus with Parasympathetic Secretomotor Fibres for glands associated with them. • Cardiac Nerves which form the Cardiac and Pulmonary Plexuses around the heart and lungs. As the main Vagus Nerves continue into the Thorax they become intimately linked with the Oesophagus and Sympathetic Nerves from the Sympathetic Trunks to form the Oesophageal Plexus. The major function of Vagus now is to control of the Gut Smooth Muscles and Glands. The extent of the PSNS in the Abdomen includes the Pancreas, Kidneys, Liver, Gall Bladder, Stomach and Gut Tube. Pelvic Splanchnic Control The Pelvic Splanchnic Nerves, S-2, S-3 and S-4, innervate the Pelvic Viscera. The tissues in the Pelvis under Parasympathetic control are: • Bladder, • Ureters, • Urinary Sphincter, • Anal Sphincter, • Uterus, • Prostate • Vagina • Penis. Article Directory: http://www.articledashboard.com For more information please visit Human Anatomy Physiology www.humananatomyphysiology.org/ |
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