219 



width of the fore part of the pelvic outlet is much increased and the passage 

 of the fetal head facilitated. 



The size of the pelvis varies not only >'n the two sexes, but also in different 

 members of the same sex. This does not appear to be influenced in any way by 

 the height of the individual. Women of short stature, as a rule, have broad 

 pelves. Occasionally the pelvis is equally contracted in all its dimensions, so 

 much so that all its diameters measure an inch less than the average, and this 

 even in women of average height and otherwise well formed. The principal 

 divergences, however, are found at the inlet, and affect the relation of the antero- 

 posterior to the transverse diameter. Thus we may have a pelvis the inlet of 

 which is elliptical either in a transverse or antero-posterior direction; the trans- 

 verse diameter in the former and the antero-posterior in the latter greatly exceeding 

 the other diameters. Again, the inlet of the pelvis in some instances is seen to 

 be almost circular. The same differences are found in various races. European 

 women are said to have the most roomy pelves. That of the negress is smaller, 

 circular in shape, and with a narrow pubic arch. The Hottentots and Bushwomen 

 possess the smallest pelves. 



FIG. 174. Diameters of the pelvic outlet in the female. 



In the fetus and for several years after birth the pelvis is small in proportion 

 to that of the adult. The cavity is deep and the projection of the sacrovertebral 

 angle less marked. The generally accepted opinion that the female pelvis does 

 not acquire its sexual characters until after puberty has been shown by recent 

 observations 1 to be erroneous, the characteristic differences between the male and 

 female pelvis being distinctly indicated as early as the fourth month of fetal life. 

 At birth these differences are distinct (Romiti), the female pelvis possessing less 

 straight ilia, a broader subpubic arch, and less height than the male. 



Surface Form. The pelvic bones are so thickly covered with muscles that it is only at cer- 

 tain points that they approach the surface and can be felt through the skin. In front, the anterior 

 superior spinous process is easily recognized; a portion of it is subcutaneous, and in thin sub- 

 jects may be seen to stand out as a prominence at the outer extremity of the fold of the groin. 

 In fat subjects its position is marked by an oblique depression among the surrounding fat, 

 at the bottom of which the bony process may be felt. Proceeding upward and outward from 

 this process, the crest of the ilium may be traced throughout its whole length, sinuously curved. 

 It is represented, in muscular subjects, on the surface, by a groove or furrow, the iliac furrow, 

 caused by the projection of fleshy fibres of the External oblique muscles of the abdomen; the 



1 Fehling, Zeitschr. fur Geburt. u. Gyniik., Band ix and x; and Arthur Thomson, Journal of Anatomy and 

 Physiology, vol. xxxiii. 



