PELVIS. 



133 



By an inverse method, proceeding on 

 Roederer's plan from the horizontal plane (j%. 

 84. , </), Nuegele determined, with great care, 

 the' angle of the inferior plane of the pelvis 

 in the living female. In 500 well-formed living 

 females placed in the erect position, he mea- 

 sured the respective distances from the ground, 

 of the tip of the coccyx, and of the lower 

 border of the pubic symphysis. He found 

 that in 454 the extremity of the coccyx was 

 higher than the symphysis pubis, the greatest 

 difference being 22 lines. In twenty-six only 

 was it lower, the greatest difference here being 

 9 lines, and in twenty they were equal in 

 height from the ground. In eleven pelves 

 where he had the opportunity of verifying his 

 observations after death, he found and figured 

 one perfect pelvis, in which the tip of the 

 coccyx was 8 lines higher than the lower 

 border of the symphysis, which corresponded 

 very nearly with the mean elevation of the 

 coccyx above the symphysis, viz. 7' I lines, 

 drawn from the observations above detailed. 

 From this he deduced the inferior angle of 

 inclination of the pelvis (fg d) to be 10 to 

 1 1 with the horizon (g, d). 



In a similar manner, in fifteen living males 

 the brothers Weber ascertained the range of 

 the altitudes of the coccyx and pubis to be 

 from 10 millimetres, the extreme difference 

 when the coccyx was lower, to 33'3 millimetres 

 when the coccyx was higher than the lower 

 border of the' symphysis pubis, the mean 

 height of the coccyx above the pubis being 

 thus 23-1 millimetres. Then, by measuring the 

 distance between the plumb lines dropped from 

 each of these points, the coccyx and pubis, 

 they ascertained the mean distance to be 75'8 

 millimetres. From these measurements they 

 obtained the angle of the inferior pelvic plane 

 with the horizon 16'51. By measuring, in two 

 dead subjects, the depth of the symphysis pu- 

 bis, and the direct vertical distance from the tip 

 of the coccyx to the sacral promontory, they 

 deduced the angle of the superior pelvic plane. 

 The superior angle, however, cannot with 

 any certainty be calculated from the inferior 

 in the living subject, on account of the un- 

 certain length and curve of the sacro-coccygeal 

 column. 



In a well-formed or standard pelvis the 

 two lines of the superior and inferior planes, 

 when prolonged anteriorly, cut each other 

 about l inch anterior to and below the 

 pelvis (at c), containing an angle of about 50 

 (e cf) ; but this will vary with the length of 

 the sacro-coccygeal column. 



According to Naegele the point at which 

 the superior plane emerges posteriorly is also 

 very variable. Most frequently it is the 

 spinous process of the second lumbar vertebra, 

 often that of the first, and sometimes between 

 the second and third. Generally the upper 

 border of the symphysis pubis was 3 inches, 

 9 to 10 lines lower than the sacral promon- 

 tory, and on a level with the union of the 

 second and third coccygeal bones. The sacro- 

 vertebral projection I have generally found 

 to be about the level of the anterior superior 



iliac spine in the male, and a little below this 

 point in the female, in a straight position of 

 the body. 



The following table shows the pelvic angles 

 of inclination in the sexes, and their difference 

 in this respect, and is drawn from the above- 

 mentioned experiments of the Webers on male, 

 and of Naegele on female subjects. 



By the inspection of the above table the 

 greater inclination of the pelvis to the spine 

 in the male will become evident, constituting 

 another distinguishing characteristic of the 



sexes. . 



The older observers estimated the pelvic 

 anMes too low, as in the incorrect drawings 

 of^Albinus, Levret, and Cloquet, where the 

 superior an^le is given as 35 with the horizon, 

 and, by Oslander, at 30. Cams gives the 

 superior at 55, and the inferior at 11 with 

 the horizon. 



Angles of the anterior and posterior pelvic 

 walls with the transverse vertical plane. 

 The pelvic inclination, in the opinion of Cm 

 veilhier, depends upon the angle which the 

 sacrum forms with the spinal column, giving 

 more or less of obliquity to the innominate 

 bones on each side. This angle (/g. 84. next 

 pa^e, a e i, and fig. 112. I. fa g, page 173), 

 winch may be called the sacra-vertebral angle t 

 I have, in as many opportunities as have oc- 

 curred to me, endeavoured to ascertain and 

 establish, with a view of comparing it with the 

 pelvi-vertebral angle in the two sexes. To do 

 this I made a vertical section of the pelvis 

 (with as many vertebrae as possible attached to 

 it), from behind forward in the median line, 

 which showed clearly the angle made by the 

 sacrum. Then, by intersecting the line of the 

 transverse vertical plane of the spinal column 

 drawn as before mentioned, by a line drawn 

 in the mean direction of the three first sacral 

 vertebra through the centre of their bodies, 

 an<"les closely approximative to the sacro- 

 vertebral ansle in the living subject were ob- 

 tained, showing the following results : 



* Weber, however, found the angle of the inferior 

 plane with the horizon to be but little less marked 

 than that of the male; making it 4'5 more than 

 the ancle of Naegele here given. Naegele remarks 

 that the inferior angle is much more variable than 

 the superior in ordinary cases. 



K .J 



