PELVIC LIMBS 673 



The relations between the length of the innominate and the length 

 of the ilium or ischinm may be represented by indices obtained by 

 fixing the length of the innominate at 100 and making the proportion, 

 innominate length : iliac length : : 100 : x. The iliac length index, 



iliac length X 100 , 39 X 100 



therefore, equals .- -; for example, - - = 57. 



innominate length bo 



I have found no noteworthy case of variations in form or develop- 

 ment, nor have I detected in the innominate any well-marked sexual 



characters. 



HUMAN INNOMINATE. 



The innominate in man has a different form from the innominate 

 in the cat ; it is lower and broader. The part of the ilium above the 

 ilio-pectineal line is strongly developed (Fig. 522), forming fully one- 

 half of the entire bone, and flaring outward to form with its fellow 

 of the opposite side a large false pelvis. It is very evident that this 

 difference is due to the assumption by man of the upright posture, 

 with the consequent weight of the abdominal viscera and the traction 

 of the abdominal wall on the upper part of the haunch bones. The 

 area by which the innominate articulates with the sacrum is on the 

 inner side of a triangular posterior prolongation which is very promi- 

 nent because of the great depth of the greater sacro-sciatic notch. 

 The part of the bone below the ilio-pectineal line forming the wall 

 of the true pelvis is triangular, and not quadrate, as in the cat. The 

 change of position of the human pelvis, due to the changed posture 

 of the whole body, has, of course, brought the long axis of the bone 

 more nearly vertical. 



The crest of the ilium is very prominent and arcuate, and the 

 distance between the anterior and posterior superior spines is much 

 increased ; hence the distance between the superior and inferior spines, 

 in front and behind, is correspondingly decreased. 



To the iliac crest are attached by its outer lip the fascia lata, and 

 the external oblique and latissimus dorsi muscles ; to the inner lip are 

 attached the transversalis, quadratus lumborum, and erector spinse 

 muscles ; to the anterior half of the space between the lips is fastened 

 the internal oblique muscle. 



The anterior inferior spine is just above the acetabulum, and not 

 separated from it, as in the cat, by a long border. It gives origin to 

 the rectus femoris muscle. 



43 



