Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 25 On the Carpus

Connection of the first bone of the thumb and the metacarpal bones to the carpus

On its lower surface, it [os trapezium] has a wide, elongated (a, b in fig. 6) depression [facies articularis basis metacarpalis I] (G in figs. 3, 6) and on its inner [medialis] (c in fig. 6) and outer [lateralis] (d in fig. 6) sides it is carved out more than in the sides and the middle; to this is connected the capitulum [basis metacarpalis] of the first internode of the thumb by means of the type of joint [articulatio carpometacarpalis pollicis] which produces a motion clear to all, quite different from the mutual connections of the carpal bones, whose motion is so inconspicuous that it can scarcely be distinguished. This is the type of articulation 45 [articulationes carpometacarpales] by which the four metacarpal bones are attached to the four carpal bones of the lower row. The first metacarpal bone [os metacarpale II], placed before the index finger [digitus secundus], is for the most part articulated to the sixth carpal bone (H in figs. 3, 4, 6), also touching a portion (h in figs. 3, 4, 6) of the fifth bone. For where the fifth bone is attached to the sixth, a common depression is carved in either bone, to which part of the head of the first metacarpal bone [basis metacarpalis II] is articulated so that the fifth carpal bone, besides touching the first and sixth, also touches the first bone of the thumb along with the first metacarpal. The second metacarpal bone [metacarpalis III], supporting the middle finger [digitus tertius], is articulated by a depressed but slanting


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head to the very lightly and obliquely carved depression (K in figs. 3, 4, 6) of the seventh carpal bone [os capitulum], slightly touching the sixth carpal bone [os trapezoideum] (k in the same figs.) with its sharper part and its inner side. The two remaining metacarpal bones [ossa metacarpi IV, V] , the ones that support the ring finger [digitus quartus] and the little finger [digitus quintus], are attached only to the eighth carpal bone [os hamatum] by smooth depressions (L and M in figs. 3, 4, 6) carved only in the surface.



Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 25 On the Carpus