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The second metacarpal bone (metacarpal bone of the index finger) is the longest, and its base the largest, of all the metacarpal bones.〔''Gray's Anatomy'' (1918). See infobox.〕 == Human anatomy == Its base is prolonged upward and medialward, forming a prominent ridge.〔 It presents four articular facets, three on the upper surface and one on the ulnar side:〔 * Of the facets on the upper surface: * * the ''intermediate'' is the largest and is concave from side to side, convex from before backward for articulation with the lesser multangular; * * the ''lateral'' is small, flat and oval for articulation with the greater multangular; * * the ''medial'', on the summit of the ridge, is long and narrow for articulation with the capitate. * The facet on the ulnar side articulates with the third metacarpal. The extensor carpi radialis longus muscle is inserted on the dorsal surface and the flexor carpi radialis muscle on the volar surface of the base.〔 This bone is often the most prone to damage from fast bowlers in cricket, as it is furthest down the bat handle on both left- and right-handers, and as such is in danger of being struck by balls that are pitched short.〔Laven , Kate. "West Indies' Courtney Walsh still in love with cricket." Daily Telegraph () 5 May 2009 Print.〕 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「Second metacarpal bone」の詳細全文を読む スポンサード リンク
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