BOXES OF THE LOWER LIMB. 



Position of the Pelvis. In the erect attitude of the body, the pelvis is 

 so inclined that the plane of the brim of the true pelvis forms an angle 

 with the horizontal, varying in different individuals from 60 to 65. The 

 base of the sacrum was found by Nagele in a large number of well-formed 

 female bodies to be about 3j inches above the upper margin of the sym- 

 physis pubis; the level of the top of the coccyx he found varying from 

 22 lines above the apex of the pubic arch to 9 lines below the same point, 

 and on an average to be V or 8 lines above it (Nagele, "Das weibliche 

 Becken," &c., Carlsruhe, 1825 ; Wood, article " Pelvis" in the Cyclopaedia of 

 Anatomy and Physiology). The pelvic aspect of the sacrum, near its base, 

 looks much more downwards than forwards, hence the sacrum appears at 

 first sight to occupy the position of the keystone of an arch ; but being in 

 reality broader at its pelvic than on its dorsal aspect, it is a keystone 

 inverted or having its broad end lowest, and is only supported in its place 

 by cartilage and ligaments. The line of pressure of the weight of the body 

 on the sacrum is directed downwards towards the symphysis pubis, and the 

 resistance of the head of the thighbone on each side is directed upwards and 

 inwards: hence in the most frequent deformities of the pelvis, arising from 



Fig. 89. Figs. 89 and 90. 



SKETCHES OF THE MALE 

 AND FEMALE PELVIS. 



As seen from above 

 and in front, or at right 

 angles to the brim of 

 the true pelvis : de- 

 signed farther to illus- 

 trate the differences of 

 the male and female 

 form, and showing in 

 the lower figure of the 

 female pelvis the lines 

 in which the dimensions 

 of the pelvis are usually 

 measured ; (these lines 

 are only marked on the 

 brim of the pelvis). 



a, p, antero- posterior 

 or conjugate diameter; 

 t, r, transverse or 

 widest diameter ; o, b, 

 0, b, oblique diameters. 



In the original speci- 

 mens, which were se- 

 lected as giving the full 

 average dimensions, the 

 following were the mea- 

 surements in inches : 



Antero-posterior or 

 conjugate diameter 

 female, 4| ; male, 4. 

 Transverse diameter 

 female, 5\ ; male, 4. 

 Oblique diameter fe- 

 male, 5; male, 4. 



insufficient strength of its walls, the sacrum is projected into the inlet of the 

 pelvis, and the acetabula approach the middle line, while the pubic bones 

 are pressed forwards and downwards between them. 



Fig. 90 



