74 



OBSTETRICS. 



direction upon the left posterior inclined plane, and falls into the 

 hollow of the sacrum. As the chin emerges, it rises up towards 

 the mons veneris, performing in this case the movement o? flexion, 

 instead of extension, as in vertex cases ; the forehead, ibllowed 

 by the sagittal suture and occiput, passes gradually down the plane 



presented to it by the 

 Fig. 20. anterior surface of the 



coccyx and perineum, 

 in front of which all 

 these parts are succes- 

 sively disengaged. (Fig. 

 20.) 



The second position 

 is merely the reverse of 

 the first / the left side 

 is now turned forwards, 

 and the left eye and 

 zygoma are lowest in 

 the pelvis, and the ec- 

 chymosis is found on 

 this side, if the labour 

 is protracted. The chin 

 rotates upon the left 

 anterior inclined plane, 

 and the anterior fonta- 

 nelle on the right pos- 

 terior one : the same 

 diameters correspond, 

 and the labour is completed as in the first position. It is said that this 

 position is more frequent than the former, and that rotation is more 

 readily effected, as the rectum offers no impediment. 



In all the various positions that have been described or alluded to, 

 the object is to bring the chin to the pubis, and the mechanism is the 

 same as in the two varieties above described. Should this fail, and 

 the chin rotate into the hollow of the sacrum, it is impossible for this 

 part to be born first (unless the foetus be an abortion) ; for the 

 thorax would then be in the pelvis at the same time as the head, and 

 would require assistance to deliver it. These cases will be treated 

 under Preternatural Labour. 



Diagnosis. — Generally speaking, it is not difficult, although the 

 face has been confounded with the breech. It is generally distin- 

 guished by the prominence and regularity of the features, by the 

 nose, eyes, chin, and mouth ; the latter is distinguished from the 

 anus by the absence of the prominence of the coccyx, and by the 

 sphincter ani ; the best means of diagnosticating face presentations 

 is by the bridge of the nose, which from its crossing the os uteri 



