244 



NOllMA L PA n TU HIT ION. 



the pelvic circumference. The determinate point on the foetus is the 

 vertebrae of the withers ; and these may be in relation with the sacrum 

 above, the pubis below, the right ascending branch of the ilium on the 

 right side, and the left ditto on the left. From this we have four 

 positions, named by Saint-Cyr as follows : 



1. Dorso-sacral Position (Vertehw-sacral Position of Eainard, Fig. 73). 

 — This is the most favourable and the most frequent of all, and is said 

 to be the only natural position. The vertebrae of the foetus correspond 

 to those of the mother, its withers touching the sacrum of the latter, 

 the belly corresponding to the abdominal parietes, and its sternum to 

 the pubis. This is sometimes named the yirs^ anterior j^osition, while 

 its sterno-dorsal diameter corresponds to the sacro-pubic diameter of 

 the parent (Fig. 74 a b). 



2. Dorso-intbic Position {Vertebro-pubic Position of Eainard). — This is 

 exactly the inverse of the first : the foetus lying on its back, its withers 



Fig. 74. 



Diameters of the Pelvis. 



a b, Superoinferior, oi- Sscro-pubic Diameter ; c d, Superior Bis-iliac Diameter ; 

 ef. Inferior Biis-iliac Diameter; ei,J'h, Oblique, Ilio-sacral, or Sacro-iliac 

 Diameters ; J K, ISIiddle Diameter. 



towards the pubis, and the sternum opposed to the sacrum of the female. 

 This is also named the second anterior position. 



3. Bight Dorso-ilial Position (Bight Vertehro-ilial Position of Bainard). 

 — The foetus lies in the left flank, its head to the right side of the 

 mother, the neck being in the same direction, and when passing 

 through the pelvic cavity, touching the ascending branch of the left 

 ilium ; then the sterno-dorsal diameter of the foetus corresponds to the 

 bis-ihac diameter passing through the centre of the pelvis (Fig. l-i,j k). 

 tlie extent of which is slightly less than the superior bis-iliac diameter. 

 The feet, when they are not in the pelvis, must, of course, be sought 

 for on the opposite side, towards the right flank of the mother. 



4. Left Dorso-ilial Position {Left Vertebro-ilial Position of Bainard). 

 — This is exactly the reverse of the last-described position, the withers 

 corresponding to the right ilium. 



The two last are sometimes named the anterior lateral j^ositions. 

 They are less frequent, as primary positions, than the first two, and 



