The development of the human body; a manual of human embryology . r-cles. Finally, in the sacral region the ribs are reduced toshort flat plates, which unite together to form the lateralmasses of the sacrum. They are usually developedonly in connection with the first three sacral vertebrae,the last two sacrals and the coccygeals having no 186 THE DEVELOPMENT OF THE HUMAN BODY. The limitation of the ribs to the three anterior sacral verte-brae is explained by the fact that primarily the pelvic girdle is inrelation only to the last two, whose ribs are consequently sup-pressed. The rib-be
The development of the human body; a manual of human embryology . r-cles. Finally, in the sacral region the ribs are reduced toshort flat plates, which unite together to form the lateralmasses of the sacrum. They are usually developedonly in connection with the first three sacral vertebrae,the last two sacrals and the coccygeals having no 186 THE DEVELOPMENT OF THE HUMAN BODY. The limitation of the ribs to the three anterior sacral verte-brae is explained by the fact that primarily the pelvic girdle is inrelation only to the last two, whose ribs are consequently sup-pressed. The rib-bearing sacral vertebrae are really membersof the lumbar series and only secondarily come into relationwith the iliac bones. The third stage in the development of the axial skeletonbegins with the ossification of the cartilages, and in eachvertebra there are typically as many primary centers ofossification as there were originally cartilages. Thus,to take a thoracic vertebra as a type, a center appears ineach half of each neural arch at the base of the transverse.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
