The development of the human body; a manual of human embryology . rranged in two distinct rows: a proximal oneconsisting of three elements, named from their relation tothe bones of the forearm, radiate, intermedium, and ulnare;and a distal one composed of four elements, termed carpa-lia. In addition, a cartilage, termed the pistform, isfound on the ulnar side of the proximal row and is gener-ally regarded as a sesamoid cartilage developed in thetendon of the flexor carpi ulnaris, and furthermore anumber of inconstant cartilages have been observed whosesignificance in the majority of cases is m
The development of the human body; a manual of human embryology . rranged in two distinct rows: a proximal oneconsisting of three elements, named from their relation tothe bones of the forearm, radiate, intermedium, and ulnare;and a distal one composed of four elements, termed carpa-lia. In addition, a cartilage, termed the pistform, isfound on the ulnar side of the proximal row and is gener-ally regarded as a sesamoid cartilage developed in thetendon of the flexor carpi ulnaris, and furthermore anumber of inconstant cartilages have been observed whosesignificance in the majority of cases is more or less accessory cartilages either disappear in later stagesof development or fuse with neighboring cartilages, or, inrare cases, ossify and form distinct elements of the of them, however, occurs so frequently as almost todeserve classification as a constant element; it is known asthe centrale (Fig. 108, c) and occupies a position betweenthe cartilages of the proximal and distal rows and appar- THE SKELETON OF THE ARM AND HAND. 209. ently corresponds to a cartilage typically present in lowerforms and ossifying to form a distinct bone. In the hu-man carpus its fate varies, as it may either disappear orunite with other cartilages, that with which it most usu-ally fuses being probably the radiale. There is evidencealso to show that another of the accessory cartilages uniteswith the ulnar element of the distal row, representingthe carpale V typicallypresent in lower of the ele-ments correspondingto an adult bone ossi-fies from a single centerwith the exception of carpale IV-V, whichhas two centers, afurther indication ofits composite charac-ter. The relation ofthe cartilages to theadult bones may beseen from the tablegiven on page 212. With regard to themetacarpals and phalanges, it need merely be stated thateach develops from a single primary center for the shaftand one secondary epiphysial center. The primarycenter appears at about the mid
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
