THE PELVIS. 105 



The depth of the little pelvis, in the female, at the symphysis 

 pubis, is an inch and a half; at the posterior part four inches, 

 or five if we include the coccyx ; and at the side three inches 

 and a half. There are many other details connected with the 

 measurements of the pelvis, which are mentioned by systematic 

 writers on midwifery. 



SECT. VI. DEVELOPMENT OF THE PELVIS. 



Three points of ossification are observable in the os innomi- 

 natum of the early foetus : one is at the superior part of the 

 ilium, another is at the tuberosity of the ischium, and the third 

 is at the angle of the pubes. The radii of ossification from 

 these centres, have extended themselves considerably at birth, 

 so as to sketch out the forms of the bones to which they re- 

 spectively belong. But these bones are separated from one 

 another by cartilage, and do not coalesce till years afterwards. 

 The union or fusion of the ilium and pubes then occurs at the 

 ilio-pectineal eminence, over the acetabulum, and partly in this 

 cavity; the ilium and ischium join in the acetabulum princi- 

 pally, and the ischium and pubes unite by their respective 

 erura at the middle of the internal side of the foramen ovale. 

 All the points of the os innominatum, most remote from the 

 primitive centres of ossification, are cartilaginous at birth: as, 

 for example, the crest, the spinous processes, the tuberosity, 

 and even the component parts of the acetabulum. The latter 

 cavity has then a triangular shape, and from its very flexible 

 and yielding condition, is incapable of affording a strong point 

 of support to the trunk in the erect position. 



At birth, the middle parts of the os sacrum, which are em- 

 ployed in protecting the spinal marrow, are more advanced in 

 their ossification than its lateral parts. The five pieces which 

 compose it, are, like the bodies of the true vertebrae, of a 

 rounded shape. The processes behind are cartilaginous. The 

 coccyx is extremely small, and scarcely presents any ossifica- 

 tion whatever. 



The pelvis of the foetus, at birth, is smaller in proportion than 

 the superior portions of the trunk; this is one of the reasons 

 why the abdomen is so projecting. The lesser pelvis is so 



