118 



THE BONES OF THE LOWER LIMB. 



posterior wall, formed by the sacrum, and coccyx, being about five inches long 

 and concave, while the anterior wall at the symphysis pubis is only one and a half 

 or two inches long, the axis is curved ; it is directed at the inlet upwards and 

 forwards towards the umbilicus, and at the outlet downwards and a little backwards 

 or forwards according to the level of the coccyx. 



Differences according to sex. The size and form of the pelvis differ 

 markedly in the two sexes. In the female the constituent bones are more slender 

 and the muscular impressions less marked ; the height is less, and the breadth and 

 capacity of the true pelvis greater ; the ilia however are more vertical, and thus 

 the false pelvis is relatively narrower than in the male ; the inlet of the true pelvis is 

 more regularly oval, the sacral j promontory projecting less into it ; the sacrum is 

 flatter and broader ; the depth of the symphysis pubis is less ; the subpubic arch 

 is much wider, and the space between the tuberosities of the ischia greater. 



The average dimensions of the pelvis, as measured in a number of full-sized 

 males and females, may be stated as follow, in inches : 



The human pelvis, compared with that of the lower animals, is characterised by its shallow- 

 ness and breadth, and by the great capacity of the true pelvis ; by the expansion of the ilia, 

 the length and sigmoid curve of their crests, the massiveness and straightness of the ischial 

 tuberosities, and the shortness of the symphysis. Similar, although much slighter, variations 

 in the form of the pelvis are to be recognized in the different races of mankind, the most 

 important of which is in the relation of the antero-posterior to the transverse diameter, and 

 is expressed by what is termed the pelvic index. This is measured at the pelvic brim ; the 

 transverse diameter is taken as the standard = 100, and the proportion of the antero-posterior 

 diameter to this gives the index. For this purpose the pelves of the two sexes must necessarily 

 be grouped separately, and the male is usually selected for comparison. The following 

 examples of the average pelvic index in the male of four races will show the range of varia- 

 tion : European, 80 ; Negro, 93 ; Australian, 97 ; Andamanese, 99. Pelves with an index 

 above 95 are dolicltopellic , from 95 to 90 inesatipellic, and below 90 platypt'llh' (Turner). 

 (Verneau, " Le bassin dans les sexes et dans les races," 1875; Garson, Journ. Anat., xvi ; 

 Turner, Journ. Anat., xx, and " Challenger " Reports, Zoology, xvi.) 



THE FEMUR. 



The femur or thigh-bone, situated between the hip-bone and the tibia, is the 

 largest and longest bone of the skeleton. In the erect position of the body it 

 inclines inwards and slightly backwards as it descends, so as to approach inferiorly 

 its fellow of the opposite side, and to have its upper end a little in advance of the 

 lower. It is divisible into the superior extremity, including the head and neck and 

 two eminences called trochanters ; the shaft ; and the inferior extremity, expanded 

 into an external and an internal condyle. 



At the superior extremity of the bone, the neck extends inwards, upwards, 



1 This diameter may be increased to the extent of one inch or more by movement of the coccyx. 



