136 Anatomy of Skeleton 



Biceps obtains some origin. The ligament is considered to be a part of the flexor 

 musculature secondarily cut off by the development of the tuberosity. 



Lesser Sciatic Notch : the internal pudic vessels and nerve do not touch the bone, 

 though they go through the foramen, but are separated by the tendon from it : the 

 nerve to the Obturator internus runs on the bone above the tendon to reach the muscle. 



Spine of Ischium. -Observe that this is incurved (Fig. 100), and the inward pro- 

 jection is less in the female than in the male. 



Greater Notch : the foramen gives exit to Pyriformis, to seven nerves, and to 

 three groups of vessels.* The typical shape of the notch differs in male and female 

 bones (Fig. 112). 



Posterior Inferior Spine gives attachment to great sciatic ligament (Fig. 34) and 

 posterior superior spine to superficial oblique band of sacro-iliac ligament. The lower 

 spine is at level of lower end of articular surface. The bone above and in front of it 

 is covered by ligamentous fibres, on the surface of which the Gluteus maximus arises. 



The main points of distinction between the male and female pelvis -with the excep- 

 tion of the breadth and curve of the sacrum and the measurements of the cavity- 

 can be appreciated on the Os innominatum. Thus the male bone is rougher, thicker, 

 and heavier than the female, and is higher proportionately. The difference in widt*h 

 between the male and female pubic arches can be appreciated on the separate bone if 

 this is held in its proper position. Also in the female the everted surface of the ischio- 

 pubic ramus is smaller, the symphysis is less deep, the acetabulum is shallower, and the 

 distance from the acetabulum to the symphysis is greater than the breadth of the 

 acetabulum, but is not so in the male. 



In the typical female bone the Great Sciatic Notch is broader and more rounded 

 than in the male (Fig. 112), and the distance between the tuberosity of the Ischium and 

 the top of the great notch is greater. 



There is a slight difference in the shape of the thyroid foramen in well-marked 

 bones, but this depends on the breadth of the ischio-pubic region ; and it may be stated 

 here that the width of the pubic arch is the principal point of distinction, and if this is 

 doubtful the other and slighter sexual characters will be doubtful also : this applies 

 with special force to the shape of the foramen and the distance between the ischial 

 tuberosities in the complete pelvis, and with less force, perhaps, to the shape of the 

 sciatic notch and the distance between the tuberosity and the margin of the notch. 



The Pre auricular Groove (Fig. 112) is as a rule only found on female bones : its 

 raison d'etre is not very apparent. 



Other sexual differences can be better appreciated when the bones are articulated : 

 thus the ilium in the female is more vertical, so that the false pelvis is relatively narrower, 

 especially when compared with the greater breadth and capacity of the true pelvis. 



The expansion of the Ilium, with its elongated curved crest, is a human character- 

 istic, as are also the shortness of the symphysis and the comparative size and strength 

 of the ischial tuberosities. The characters of the ilium and the great capacity of the 

 true pelvic cavity give the human character of relative shallowness to the pelvis as 

 a whole. 



The ilium corresponds with the body of the scapula in being the dorsal element in 

 the girdle, but the doubtful value of the ventral elements in the shoulder girdle precludes 

 any definite comparison with the ischium and pubis, which are the ventral bars of the 

 hip girdle. Definite homologies have been sought between the various parts of the 



* Sciatic, pudic, and gluteal vessels, N. great and small sciatic, internal pudic, N. to Obturator, Quad- 

 ratus femoris, upper and lower gluteal. 



