Efferent nerve

This refers to the nerves that transmit nerve excitation (nerve impulses) from the central nervous system to peripheral organs. They are also called efferent nerves, and are the opposite of afferent nerves. They are roughly synonymous with motor nerves (the opposite of sensory nerves) in a broad sense, including nerves that control muscle contraction, glandular secretion, and the excitability of receptor cells. Since efferent and afferent nerve fibers are mixed within a nerve trunk, the entire nerve bundle is not efferent. The autonomic nervous system is all efferent, except when the afferent nerves that are distributed to the internal organs are included.

[Akira Murakami]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

神経興奮（神経インパルス）を中枢より末梢(まっしょう)器官に伝える神経をいう。遠心性神経ともいい、求心神経の対語である。筋収縮や腺(せん)の分泌、さらに受容器細胞の興奮性を制御する神経を含む広義の運動神経（感覚神経の対語）とほぼ同義。神経幹中には遠心神経繊維と求心神経繊維とが混在するので、神経束全体が遠心性ということはない。自律神経系は、内臓に分布する求心神経を含める場合を除き、すべて遠心性である。

［村上　彰］

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