The development of the human body; a manual of human embryology . velopment there is no neck, the head beingpractically sessile. As development proceeds the innerupper portion of the shaft grows more rapidly than theouter portion, carrying the head away from the great tro-chanter and forming the neck of the bone. The acetabu-lum is shallower at birth than in the adult and cannotcontain more than half the head of the femur; conse-quently the articular portion of the head is much lessextensive than in the adult. POST-NATAL DEVELOPMENT. 517 It is a well-known fact that the new-born child habitu-a
The development of the human body; a manual of human embryology . velopment there is no neck, the head beingpractically sessile. As development proceeds the innerupper portion of the shaft grows more rapidly than theouter portion, carrying the head away from the great tro-chanter and forming the neck of the bone. The acetabu-lum is shallower at birth than in the adult and cannotcontain more than half the head of the femur; conse-quently the articular portion of the head is much lessextensive than in the adult. POST-NATAL DEVELOPMENT. 517 It is a well-known fact that the new-born child habitu-ally holds the feet with the soles directed toward one an-other, a position only reached in the adult with somedifficulty, and associated with this supination or inversionthere is a pronounced extension of the foot (i. e., flexionupon the leg as usually understood; see p. 107), it beingdifficult to flex the childs foot beyond a line at right angleswith the axis of the leg. These conditions are due appar-ently to the extensor and tibialis muscles being relatively. r * Fig. 270.—Longitudinal Sections op the Head of the Femur of (A) New-born Child and (B) a Later Stage of Development. ep, Epiphysial center for the head; /;, head; /.trochanter.—(Henke.) shorter and the opposing muscles relatively longer than inthe adult, and with the elongation or shortening, as thecase may be, of the muscles on the assumption of the erectposition, the bones in the neighborhood of the ankle-jointcome into new relations to one another, the result being amodification of the form of the articular surfaces, espe-cially of the astragalus. In the child the articular carti-lage of the trochlear surface of this bone is continued on-ward to a considerable extent upon the neck of the bone,which comes into contact with the tibia in the extreme 518 THE DEVELOPMENT OF THE HUMAN BODY. extension possible in the child. In the adult, however,such extreme extension being impossible, the cartilageupon the neck gra
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
