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The axillary nerve or the circumflex nerve is a nerve of the human body, that originates from the brachial plexus (upper trunk, posterior division, posterior cord) at the level of the axilla (armpit) and carries nerve fibers from C5 and C6. The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein. ==Structure== The nerve lies at first behind the axillary artery, and in front of the subscapularis, and passes downward to the lower border of that muscle. It then winds backward, in company with the posterior humeral circumflex artery, through a quadrilateral space bounded above by the subscapularis, below by the teres major, medially by the long head of the triceps brachii, and laterally by the surgical neck of the humerus, and divides into an anterior, a posterior, and a collateral branch to the long head of the triceps brachii branch. * The ''anterior branch'' (upper branch) winds around the surgical neck of the humerus, beneath the deltoid muscle, with the posterior humeral circumflex vessels. It continues as far as the anterior border of the deltoid to provide motor innervation. The anterior branch also gives off a few small cutaneous branches, which pierce the muscle and supply in the overlaying skin. * The ''posterior branch'' (lower branch) supplies the teres minor and the posterior part of the deltoid. The posterior branch pierces the deep fascia and continues as the superior (or upper) lateral cutaneous nerve of arm, which sweeps around the posterior border of the deltoid and supplies the skin over the lower two-thirds of the posterior part of this muscle, as well as that covering the long head of the triceps brachii. * The motor branch of the long head of the triceps brachii arises, on average, a distance of 6 mm (range 2–12 mm) from the terminal division of the posterior cord termination.〔 * The trunk of the axillary nerve gives off an articular filament which enters the shoulder joint below the subscapularis. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Axillary nerve」の詳細全文を読む スポンサード リンク
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