WordNet

(physical chemistry) a sample of matter in which substances in different phases are in equilibrium; "in a static system oil cannot be replaced by water on a surface"; "a system generating hydrogen peroxide"
instrumentality that combines interrelated interacting artifacts designed to work as a coherent entity; "he bought a new stereo system"; "the system consists of a motor and a small computer"
a group of independent but interrelated elements comprising a unified whole; "a vast system of production and distribution and consumption keep the country going" (同)scheme
a complex of methods or rules governing behavior; "they have to operate under a system they oppose"; "that language has a complex system for indicating gender" (同)system of rules
a group of physiologically or anatomically related organs or parts; "the body has a system of organs for digestion"
a procedure or process for obtaining an objective; "they had to devise a system that did not depend on cooperation"
the living body considered as made up of interdependent components forming a unified whole; "exercise helped him get the alcohol out of his system"
easily agitated; "a nervous addict"; "a nervous thoroughbred"
of or relating to the nervous system; "nervous disease"; "neural disorder" (同)neural

PrepTutorEJDIC

〈C〉(関連した部分から成る)『体系』,系統,組織[網],装置 / 〈C〉(教育・政治などの)『制度』,機構;《the~》体制 / 〈C〉(思想・学問などの)『体系』,学説 / 〈C〉(…の)『方法』,方式,やり方《+of doing》 / 〈U〉正しい方針(筋道,順序) / 〈U〉《the~》(身体の)組織,系統 / 〈U〉《the~,one's~》身体,全身
『神経の』 / 『神経質な』,神経過敏な / 『心配な』,不安な
身体の / 体腔(たいこう)の / 体細胞の

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/25 23:00:01」(JST)

wiki en

For the musician known as Somatic, see Hahn Rowe.

The somatic nervous system (SoNS or voluntary nervous system) is the part of the peripheral nervous system^[1] associated with skeletal muscle voluntary control of body movements. The SoNS consists of afferent and efferent nerves. Afferent nerves are responsible for relaying sensation to the central nervous system; efferent nerves are responsible for stimulating muscle contraction, including all the non-sensory neurons connected with skeletal muscles and skin.

Parts of somatic nervous system

There are 43 segments of nerves in the human body. With each segment, there is a pair of sensory and motor nerves. In the body, 31 segments of nerves are in the spinal cord and 12 are in the brain stem.

Besides these, thousands of association nerves are also present in the body.

Thus somatic nervous system consists of three parts:

Spinal nerves: They are peripheral nerves that carry sensory information into and motor commands out of the spinal cord.
Cranial nerves: They are the nerve fibers that carry information into and out of the brain stem. They include smell, vision, eye, eye muscles, mouth, taste, ear, neck, shoulders, and tongue.
Association nerves: These nerves integrate sensory input and motor output numbering thousands.

Nerve signal transmission

The somatic nervous system controls all voluntary muscular systems within the body, and the process of involuntary reflex arcs.

The basic route of nerve signals within the efferent somatic nervous system involves a sequence that begins in the upper cell bodies of motor neurons (upper motor neurons) within the precentral gyrus (which approximates the primary motor cortex). Stimuli from the precentral gyrus are transmitted from upper motor neurons and down the corticospinal tract, via axons to control skeletal (voluntary) muscles. These stimuli are conveyed from upper motor neurons through the ventral horn of the spinal cord, and across synapses to be received by the sensory receptors of alpha motor neurons (large lower motor neurons) of the brainstem and spinal cord.

Upper motor neurons release a neurotransmitter, acetylcholine, from their axon terminal knobs, which are received by nicotinic receptors of the alpha motor neurons. In turn, alpha motor neurons relay the stimulus.

From there, acetylcholine is released from the axon terminal knobs of alpha motor neurons and received by postsynaptic receptors (Nicotinic acetylcholine receptors) of muscles, thereby relaying the stimulus to contract muscle fibers.

Vertebrate and invertebrate differences

In invertebrates, depending on the neurotransmitter released and the type of receptor it binds, the response in the muscle fiber could either be excitatory or inhibitory. For vertebrates, however, the response of a muscle fiber to a neurotransmitter – always acetylcholine (ACh) – can only be excitatory.

Reflex arcs

A reflex arc is a neural circuit that creates a more or less automatic link between a sensory input and a specific motor output. Reflex circuits vary in complexity—the simplest spinal reflexes are mediated by a two-element chain, of which in the human body there is only one, also called a monosynaptic reflex (there is only one synapse between the two neurones taking part in the arc: sensory and motor). The singular example of a monosynaptic reflex is the patellar reflex. The next simplest reflex arc is a three-element chain, beginning with sensory neurons, which activate interneurons in the spinal cord, which then activate motor neurons. Some reflex responses, such as withdrawing the hand after touching a hot surface, are protective, but others, such as the patellar reflex ("knee jerk") activated by tapping the patellar tendon, contribute to ordinary behaviour.

References

^ "somatic nervous system" at Dorland's Medical Dictionary

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 身体化：疫学、病因、臨床的特徴、医学的評価、および診断 somatization epidemiology pathogenesis clinical features medical evaluation and diagnosis
2. 身体化：治療および予後 somatization treatment and prognosis
3. 成人における転換性障害：用語、診断および鑑別診断 conversion disorder in adults terminology diagnosis and differential diagnosis
4. 症候性（二次性）ミオクローヌス symptomatic secondary myoclonus
5. 成人における転換性障害：治療 conversion disorder in adults treatment

English Journal

Effects of normal aging on myelin sheath ultrastructures in the somatic sensorimotor system of rats.

Xie F1, Liang P2, Fu H1, Zhang JC3, Chen J1.
Molecular medicine reports.Mol Med Rep.2014 Jul;10(1):459-66. doi: 10.3892/mmr.2014.2228. Epub 2014 May 9.
Previous studies have presented qualitative and quantitative data regarding the morphological changes that occur peripherally in myelin sheaths and nerve fibers of rats during their lifespan. However, studies on ultrastructural features of myelinated fibers (MFs) in the central nervous system (CNS)
PMID 24818843

Therapeutic benefit of lentiviral-mediated neonatal intracerebral gene therapy in a mouse model of globoid cell leukodystrophy.

Lattanzi A1, Salvagno C2, Maderna C2, Benedicenti F2, Morena F3, Kulik W4, Naldini L2, Montini E2, Martino S3, Gritti A5.
Human molecular genetics.Hum Mol Genet.2014 Jun 15;23(12):3250-68. doi: 10.1093/hmg/ddu034. Epub 2014 Jan 23.
Globoid cell leukodystrophy (GLD) is an inherited lysosomal storage disease caused by β-galactocerebrosidase (GALC) deficiency. Gene therapy (GT) should provide rapid, extensive and lifetime GALC supply in central nervous system (CNS) tissues to prevent or halt irreversible neurologic progression.
PMID 24463623

Roles of innervation in developing and regenerating orofacial tissues.

Pagella P1, Jiménez-Rojo L, Mitsiadis TA.
Cellular and molecular life sciences : CMLS.Cell Mol Life Sci.2014 Jun;71(12):2241-51. doi: 10.1007/s00018-013-1549-0. Epub 2014 Jan 7.
The head is innervated by 12 cranial nerves (I-XII) that regulate its sensory and motor functions. Cranial nerves are composed of sensory, motor, or mixed neuronal populations. Sensory neurons perceive generally somatic sensations such as pressure, pain, and temperature. These neurons are also invol
PMID 24395053

Japanese Journal

体性感覚刺激による内分泌機能の反射性調節

鈴木はる江
人間総合科学 : 人間総合科学大学紀要 (24), 13-21, 2013-03
NAID 40019796332

Generation of Induced Pluripotent Stem Cells from Asian Patients with Chronic Neurodegenerative Diseases

LUO Yumei,FAN Yong,CHEN Xinjie [他],YU Bolan,YUE Lei,WANG Ding,LI Qing,CHEN Yaoyong,SUN Xiaofang
The Journal of reproduction and development 58(5), 515-521, 2012-10-01
… In this study, we have generated iPS cells from Asian patients with chronic degenerative diseases of the nervous system, including spinal muscular atrophy (SMA), Parkinson disease (PD) and amyotrophic lateral sclerosis (ALS) by transduction with four factors (KLF4, SOX2, OCT4 and c-MYC). … All of the iPS cells showed pluripotency similar to that of human embryonic stem cells (hESCs) and were able to differentiate into various somatic cell types in vitro and in vivo. …
NAID 10031123294

発達障害の身体問題(感覚情報調整機能障害・身体症状・身体運動)の諸相 : 発達障害の当事者調査から

高橋智,田部絢子,石川衣紀
障害者問題研究 40(1), 34-41, 2012-05
本稿では,発達障害の本人・当事者がどのような身体問題(感覚情報調整機能障害・身体症状・身体運動の困難)を抱えているのかを,当事者への質問紙法調査(感覚情報調整機能障害調査,身体症状調査,体育・スポーツの困難・ニーズ調査)を通して明らかにしてきた.その結果,例えばニキの「自閉症は身体障害である」,片岡の「(内分泌調節,自律神経調節などの)発達障害の身体障害性への援助はまさに発達障害者へのバリアフリー …
NAID 110009209363