PARTURITION. 493 



these varieties may, therefore, be reduced to the one now named, and which 

 may be either direct or oblique, according as the case may be. 



Sterno-abdominal Presentation. — The limbs in this are in reality first 

 touched, and we may have all four, or only three or two ; these, however, 

 are not the fixed point of the p»resentation, which is the inferior part of 

 the body — or sterno-abdominal region — hence the designation. 



These four principal presentations may be divided into natural or 

 normal, in which spontaneous or unaided birth is possible ; and into un- 

 natural or abnormal, in Avhich parturition is impossible without the inter- 

 vention of man. The longitudinal presentations alone comprise the first, 

 although they are not always normal; as a wrong direction of the head 

 or limbs may prove an obstacle more or less difficult to overcome, and 

 may require the aid of art. So that, taking this view into consideration, 

 the presentations may either be simple or more or less complicated, accord- 

 ing to circumstances. 



XII. Positions of Foal. 



The presentation being determined by the part of the foetus which offers 

 at the pelvic inlet, it must be evident that this part, whichever it may be, 

 may vary considerably in its relations to the circumference of that passage. 

 If the chest of the ftrtus first enters it, the attitude of this region may be 

 very different in different cases; in one the withers may correspond to the 

 sacrum of the mother, and the sternum to the pubis, or the reverse may 

 happen ; in another the fa?tus may be lying on the right side, the sternum 

 corresponding to the right branch of the mother's ilium, and the withers 

 to the left ilium, or vice versa. So that here are four different positions 

 in the same presentation — the anterior; and it will readily be understood 

 that it should be the same, or nearly the same, for the other presentations. 



The position has accordingly been defined to be the relation of a deter- 

 minate point on the surface of the foetus, to an equally determinate point 

 of the pelvic circumference. The points, so far as the mother is concerned, 

 may be determined once for all, and they will always remain the same for 

 every presentation ; they may be, for instance, the sacral region above, the 

 pubic below, and the two ascending branches of the ilium at the sides. If, 

 with the fcBtus, we select any region — say .the withers — and put this part in 

 relation with any of these four points of the pelvic circumference, we shall 

 have four successive and easily recognized positions. If, therefore, we 

 first give the name of the region in the foetus, and next that of the pelvic 

 circumference with Avhich it is in relation, -we have a ready means of desig- 

 nating the positions : describing the foetus to be in vertebrosacral 

 position — for instance, when it.? vertebral region is in relation with the 

 sacrum of the mother. The fixed points may be invariable in the latter; 

 but they cannot be so with the foetus, as they will vary with each oresen- 

 tation. 



