It is an integral part of the entire nervous systemCentral nervous systemIt also exists in the peripheral nervous system, mainly distributed in the viscera, cardiovascular and glands.Like the somatic nerve, the visceral nerve contains sensory and motor nerve fibers.
Visceral nerves mainly regulate the secretion of viscera, cardiovascular system and glands. They are not controlled and controlled by human will and are not random, so some people call them autonomic nerves;Because it mainly controls and regulates the metabolic activities shared by animals and plants, and does not dominate the unique skeletal muscles of animals, it is called vegetative nerve.Visceral sensory nerve, like somatic sensory nerve, its sensory neurons are also located in the brain and spinal ganglia, and distributed in the visceral and cardiovascular receptors. This receptor transmits the perceived stimulus through the visceral sensory nerve to the central centers at all levels, and also to the cortex of the big brain, but the visceral sense is relatively vague.According to the information transmitted, the central nervous system regulates the activities of internal organs through visceral motor nerves.
visceral motor nerve
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The difference between visceral movement and somatic motor nerve is:
The lower level center of sympathetic nerve is located in the cervical 8 or thoracic 1 to lumbar 3 segmentsspinal cordGray lateral horn,neuronOfaxonThe formation of preganglionic fibers along the spinal cordAnterior rootandspinal nerveTo sympatheticganglion。
Sympathetic ganglia: Sympathetic ganglia are sympathetic nervesPostganglionic neuronSomaThe location of the.It can be divided into paravertebral segment and anterior segment.Paravertebral segments are longitudinally arranged on both sides of the spine, with 22-25 segmentsnerve fiberConnectSympathetic trunk。The sympathetic trunk has three segments in the cervical segment, namely the superior cervical segment, the middle cervical segment and the lower cervical segment. The lower cervical segment often combines with the thoracic 1 sympathetic segment to form a stellate ganglion.Sympathetic trunk has 11-12 segments in the thoracic segment;The lumbar segment often has 4 segments;The sacral segment has 4-5 segmentsCoccygeal boneThe left and right sympathetic trunks in front meet to form a common caudal sympathetic segment or odd segment.The anterior segment is located in front of the spine, with celiac segments on both sides of the celiac artery root;Aortic renal segment, located at the root of renal artery;mesenteryThe superior segment and the inferior mesenteric segment are located at the beginning of the artery of the same name.
Pre festival fiber fromspinal cordThe lateral median nucleus of C8-3 segment has three directions: it terminates at the corresponding paravertebral segment;staySympathetic trunkThe inner part rises or falls first and then ends at the upper or lower paravertebral segment; ③It passes through the paravertebral segment and forms the major and minor splanchnic nerves to the anterior vertebral segmentneuron。
Postganglionic fibers also have three directions: return to the spinal nerve via the gray communicating branch;With angiogenesisPlexus, organs distributed along arteries;Go directly to the organs under control.
(1) Neck: three necksganglion, issuedPostganglionic fibreThere are three directions.The blood vessels, sweat glands, and erector muscles of the head, neck, and upper limbs are distributed by the cervical nerves accompanying the gray communication;Forming vascular plexus to adjacent blood vessels,Internal carotid arteryPlexusExternal carotid arteryPlexusclavicleLower plexusvertebral arteryClump, etc;Directly form nerves, supracardiac, middle and inferior nerves, etc.
(2) Thorax: The thoracic sympathetic ganglion sends out postganglionic fibers in three directions.12 pairs of thoracic nerves were distributed to the blood vessels, sweat glands and erector muscles of the thoracoabdominal wall through the gray communication;The upper 5 pairs of thoracic segments send out branches to form a plexus, including thoracic aortic plexus, esophageal plexus, pulmonary plexus, cardiac plexus, etc;Directly form nerves, such as big and small splanchnic nerves.
(3) Waist andPelvic region: The same neck and chest have three directions.
Visceral motor nerves are divided into sympathetic and parasympathetic nerves.The neuronal bodies of the sympathetic preganglionic fibers are located in the lateral horn of the gray matter of the thoracic spinal cord and lumbar spinal cord segments 1-3.The neuronal cell bodies of the preganglionic fibers of the parasympathetic nerves are located in the anterior horn of the gray matter of the brain stem and the second to fourth segments of the sacral spinal cord.The visceral nervous system is to manage and regulate the important life activities of the human body (breathing, circulation, digestion, temperature regulation, metabolism, etc.) under the regulation of the cortex and subcortical center.
Visceral sensory nerve fiber is a part of sensory nerve fiber.The visceral sensory nerve fibers are mixed in the sympathetic and parasympathetic nerves, and there is no separate visceral sensory nerve.The number of visceral sensory fibers is small, and the distribution range of each sensory fiber is wide, so the visceral sensation is slower than that of the body, with poor localization.Its sensory fibers are transmitted to the central nervous system through the posterior root of spinal nerve and vagus nerve.In clinical practice, some visceral diseases can produce pain or allergy zones in different skin regions, which is due to the fact that the diseased organs and skin allergy zones are innervated by the same nerve segment.
