182 



THE SKELETON. 



plane of 



FIG. 125. Vertical section of the pelvis, 

 with lines indicatingthe axisof the pelvis. 



Differences between the Male and the Female Pelvis. The female pelvis, looked 

 at as a whole, is distinguished from the male by the bones being more delicate by 



its width being greater and its depth smaller. 

 The whole pelvis is less massive, and its bones 

 are lighter and more slender, and its muscular 

 impressions are slightly marked. The iliac fossae 

 are shallow, and the anterior iliac spines widely 

 separated ; hence the greater prominence of the 

 hips. The inlet in the female is larger than in 

 the male ; it is more nearly circular, and the 

 sacro-vertebral angle projects less forward. The 

 cavity is shallower and wider; the sacrum is 

 shorter, wider, and less curved ; the obturator 

 foramina are triangular, and smaller in size than 

 in the male. The outlet is larger and the coc- 

 cyx more movable. The spines of the ischia 

 project less inward. The tuberosities of the 

 ischia and the acetabula are wider apart. The 

 pubic arch is wider and more rounded than in 

 the male, where it is an angle rather than an 

 arch. In consequence of this the width of the 

 fore part of the pelvic outlet is much increased 

 and the passage of the foetal head facilitated. 

 The size of the pelvis varies, not only in 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 transverse 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. 

 In the foetus and for several years afterbirth the pelvis is small in proportion 

 to that of the adult. The cavity is deep, and the projection of the sacro-vertebral 

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

 riot 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 foetal life. 



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 to be recognized ; a portion of it is subcutaneous, 

 and in thin subjects 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 amongst the sur- 

 rounding 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 fur- 

 row, the iliac furrow, caused by the projection of fleshy fibres of the External oblique muscle 

 of the abdomen ; the iliac furrow lies slightly below the level of the crest. It terminates behind 

 in the posterior superior spinous process, the position of which is indicated by a slight depression 

 on a level with the spinous process of the second sacral vertebra. Between the two posterior 

 superior spinous processes, but at a lower level, is to be felt the spinous process of the third 

 sacral vertebra (see page 53). Another part of the bony pelvis which is easily accessible to the 



1 Fehling, Zeitschr.fiir Geburt. u. Gynaek., Bd. ix. und x. ; and Arthur Thomson, Journal of Anatomy 

 and Physiology, vol. xxxiii. 



