PRESENTATION OF THE VERTEX. 305 



B. Second Variety. 

 Right fronto-acetabular position. ' . 



5th position of Baudelocque, Gardien, Dubois, Desormeaux, Madame Boivin, 

 &c.; 4th of Maygrier, Capuron, Duges, Madame Lacliapelle, &c.: 92 in 20,517 

 cases, Madame Boivin; 66 in 22,243 cases, Madame Lachapelle. 



746. The right fronto-acetabular position, although rather more 

 rare than the preceding one, is, notwithstanding, more co'mmon, 

 relatively to the opposite fronto-acetabular position, than the right 

 occipito-acetabular is when compared to the left occipito-acetabular 

 position. This peculiarity comes in support of the opinion I ad- 

 vanced when detailing the causes of the first position of the vertex: 

 it may in fact be conceived, that if once placed behind, at the supe- 

 rior strait, the occiput may descend almost indifferently to the right 

 or left of the median line, while, if turned forwards, it must be most 

 frequently repelled towards the left side. 



In this position the back of the foetus is directed to the left and 

 backwards, the right shoulder to the left and forwards; the bi-parietal 

 diameter represents the left antero-oblique diameter; the occipito- 

 bregmatic is parallel with the right antero-oblique; and the lesser cir- 

 cumference and occipito-mental diameter are parallel with the plane 

 and axis of the strait. The head, when engaged in the excavation, 

 revolves a half quarter of a circle upon its vertical axis. The occi- 

 put, sliding upon the left posterior inclined plane, proceeds to lodge 

 in the hollow of the sacrum; wliile the bregma, rolling upon the 

 right anterior inclined plane, is directed to the symphysis pubis. 



Upon emerging from the vulva, when the act of restitution takes 

 place, the occiput gradually turns towards the inside of the left thigh, 

 and not the right, as in the fourth position. As to the rest of the 

 labor, it is terminated like the former, except that the front of the 

 foetus at last looks towards the right, and its right side directly in 

 front, whereas in the other variety, dirgctly the reverse is observed. 

 Moreover, it is said to be rather more difficult, in consequence of the 

 presence of the rectum, which must retard the progress of the occiput. 



747. M. Nsegele maintains that the fourth position of the vertex 

 is much more common than the second, and that the French ac- 

 coucheurs did not perceive it, because, being led away by the autho- 

 rity of Baudelocque, they did not perceive that the former of these 

 two positions commonly converts itself into the right occipito-aceta- 

 bular position, as soon as the head gets through tlie superior strait.* 



* My own experience in midwifery is in perfect accordance v/ith M. Naegele's 

 assertion on this point. — M. 



27* 



