A theoretical and practical treatise on midwifery : including the diseases of pregnancy and parturition and the attentions required by the child from birth to the period of weaning . incipal diameters at that point, namely— 1. The antero-posterior or coccy-pubaldiameter (a a, Fig. 4), running from thepoint of the coccyx to the summit of thepubic arch; it is usually four and aquarter inches long, but may increase tofour and three-quarter inches duringlabor, by the retrocession of the coccyx. 2. The bis-ischiatic, or transverse diam-eter, b b: is four and a quarter inchesin length, and goes from
A theoretical and practical treatise on midwifery : including the diseases of pregnancy and parturition and the attentions required by the child from birth to the period of weaning . incipal diameters at that point, namely— 1. The antero-posterior or coccy-pubaldiameter (a a, Fig. 4), running from thepoint of the coccyx to the summit of thepubic arch; it is usually four and aquarter inches long, but may increase tofour and three-quarter inches duringlabor, by the retrocession of the coccyx. 2. The bis-ischiatic, or transverse diam-eter, b b: is four and a quarter inchesin length, and goes from one tuberosityof the ischium to the other. 3. Theoblique diameter, c c, commences at themiddle of the great sacro-sciatic liga-ment, and crosses to the point of unionof the ascending branch of the ischium,with the descending ramus of the pubis, and is four and a quarter inches long, but may become one-quarter of an iuchmore during labor, from the elasticity of these ligaments. All the diameters of the inferior strait are, therefore, in the dried pelvis, aboutfour and a quarter inches in length, though their dimensions are susceptible ofgreat variation during labor. Fig. a a. The antero-posterior or coccy-pubal diame-ter, b b. The transverse or bis-ischiatic diameterc c. The two oblique diameters. OF THE PELVIS, 49 § 5. Op the Excavation. The excavation is that space comprised between the superior and the inferiorstraits, and it is in this cavity that the foetal head executes its principal move-ments; and it is somewhat surprising, that, until quite recently, this canal wasscarcely mentioned in the majority of the classic works, notwithstanding theimportance of a knowledge of its dimensions, as also of the direction of its planeand axis. Its dimensions comprise both the height and width at the different points:thus the height in front, is one and a half inches; upon the sides, three andthree-quarter inches; whilst it is four and a quarter inches behind, if a straightline
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Keywords: ., boo, bookcentury1800, booksubjectmidwifery, booksubjectobstetrics
