Elements of the principles and practice of midwifery . see fig. 3): he says, To form an exact _. „ Fig. 3. idea of the general dis-position of the pelviccavity, it seems bestto cut that canal by aseries of planes, pass-ing from the point c(the point of intersec-tion of the planes ofthe superior and infe-rior straits,) to thepoints p, q, r, s, t, ofthe anterior face of thesacrum. Each one of ^these planes will de-termine the oppning of the pelvic cavity at that point. Now, to determine with precisionthe direction of the general axis of the excavation, it will be neces-sary to erect a perpendicu
Elements of the principles and practice of midwifery . see fig. 3): he says, To form an exact _. „ Fig. 3. idea of the general dis-position of the pelviccavity, it seems bestto cut that canal by aseries of planes, pass-ing from the point c(the point of intersec-tion of the planes ofthe superior and infe-rior straits,) to thepoints p, q, r, s, t, ofthe anterior face of thesacrum. Each one of ^these planes will de-termine the oppning of the pelvic cavity at that point. Now, to determine with precisionthe direction of the general axis of the excavation, it will be neces-sary to erect a perpendicular to the geometrical centre of each oneof these sections, and to draw a line (gk) along the extremities ofthese perpendiculars. This line (gk) is curved, and is called thegeneral axis of the pelvic cavity. It is easy to see that this line isnearly parallel with the anterior face of the sacrum, and its extremitiesare lost in the axes of the superior and inferior strait. This curverepresents exactly the axis of the whole excavation; that is to say,. 34 THE PELVIS the line which the foetus traverses in passing through the should be observed that the axis of the pelvis is not composed oftwo straight lines, nor does it form the arc of a circle, as has beensupposed by Carus and others; but that its upper portion, whichcorresponds to the two first bones of the sacrum, is nearly straight,while the lower represents a curve parallel to that of the sacrum andcoccyx. We will see hereafter that this curved axis is much ex-tended, by the soft parts which lie between the extremity of thecoccyx and the posterior commissure ef the vulva. The depth of the pelvic excavation posteriorly is about 6 inches,laterally 3£ inches, and anteriorly the symphisis pubis measuresfrom 1| to 2 inches. Its diameters are : 1. An antero-posterior dia-meter, extending from the symphisis pubis to the centre of the sacrum,measures 4£ inches or more. 2. A transverse diameter, passingfrom the plane of o
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Keywords: ., boo, bookcentury1800, booksubjectmidwifery, booksubjectobstetrics
