132 



PELVIS. 



line those of the superior and inferior outlets pelvis to the vertebral column is obtained, 

 of the pelvis, the general inclination of the The line so drawn will generally be found to 



VARIATIONS in the Diameters of healthy Female Pelves. 



Like male pelvis, diameters small. 



Smallest pelvis, transverse diameter of cavity 4|, of outlet 4|. 



Belong to the same pelves respectively (compensating diameters). 



pass also through the bodies of the first dorsal 

 and second lumbar vertebrae across their 

 centres. The curved line of the vertebras, in 

 most well-formed subjects, cuts the straight 

 line at these two points, in passing from the 

 cervical to the dorsal, and from the latter to the 

 lumbar curve. 



The plane of the pelvic brim has been 

 termed by Naegele and the brothers G. and 

 E. Weber the superior plane of the pelvis, and 

 that of the inferior outlet the inferior plane. 

 These observers measured the angle formed 

 by these planes with the ground-level in the 

 standing position, i. e. with the horizon, or 

 with a plane drawn horizontally, at right 

 angles, to the above-mentioned transverse 

 vertical plane, which, in the erect posture, 

 was found to be perpendicular to the base of 

 support. The angle which the superior plane 

 of the pelvis forms with the transverse vertical 

 plane or with the horizon is termed by them the 

 angle of inclination of the pelvis, or the pelvi- 

 vertebral angle (fig- 84. page 134*.), (ae, ec). 



It is remarkable that, in man only, are the 

 boundaries of the superior outlet in one plane, 

 i. e. in man only is the direction of the superior 

 pubic ramus in the same plane with that of the 

 cotylo-sacral rib of the ilium. In all other ani- 

 mals, as far as my own observations go, the 

 pubis is bent backward or forward, so as to 

 make an angle with the ilium, and the pelvi- 

 vertebral angle is thus resolved into two 

 angles, a vertebro-iliac and an ilio-pubic, 



The angle of the superior plane was found 

 by the Webers on the dead body, by fixing 

 the connected spinal column and pelvis of a 

 recent well-made subject, in plaster of Paris, 

 to preserve the natural position, then making 

 through the whole a direct vertical section, 

 and afterwards measuring off the angles. 



On making a transverse vertical section 

 through the centres of the heads of the 

 femurs and cotyloid cavities, they also found 

 that, when the body is in the erect position 

 and the pelvis at the proper angle, the coty- 

 loid notch and depression, and the fibres of 

 the ligamentum teres, have an almost directly 

 vertical direction, and fall exactly in the trans- 

 verse vertical plane of the vertebrae (see fg. 

 87. page 140., in which the line a a' lies in 

 the plane of the transverse vertical section). 

 It will be further seen, by inspecting the figure, 

 that this plane, being continued downwards, 

 crosses the obturator foramina, and falls very 

 nearly in the line of suture of the ischio-pubic 

 rami. And this will be found to be the case, 

 with a plumb line dropped from the sacral pro- 

 montory, which is cut by the above plane in 

 the erect position of the pelvis. A detached 

 pelvis may be placed in the erect living po- 

 sition, consequently, by keeping the poste- 

 rior part of the notch the most depending 

 point of the cotyloid brim, and its inclinations 

 will then accord with those taken in connec- 

 tion with the spine. 



In the consideration of these pelvic angles 

 it must be borne in mind that the direction 

 of the curve of the three last lumbar vertebrae, 

 below the point where the great dorsal con- 

 cavity terminates, is such that, if prolonged 

 upwards, the axial line would pass out at the 

 junction of the manubrium with the body of 

 the sternum. This makes the pelvi-lumbar 

 angle much less in man than the whole pelvi- 

 vertebral ; a circumstance to be borne in mind 

 in comparing them with those of animals. In 

 fact, the transvertical section just mentioned 

 passes through the body of the third lumbar 

 vertebra considerably posterior to its centre in 

 most cases (see a, b^g. 84. page 134.). 



