864 



GENERATION. 



usually about three inches in length, two in breadth, at its widest portion, and one inch in 

 thickness. Its weight is from one and a half to two and a half ounces. It is somewhat 

 loosely held in place by the broad and round ligaments and by the folds of the peritoneum 

 in front and behind. The delicate layer of peritoneum which forms its external covering 

 extends behind as far down as the vagina, where it is reflected back upon the rectum, and 

 anteriorly, a little below the upper extremity of the neck (os internum), where it is re- 

 flected upon the urinary bladder. At the sides of the uterus, the peritoneal covering, a lit- 

 tle below the entrance of the Fallopian tubes, becomes loosely attached and leaves a line 

 for the penetration of the vessels and nerves. Fig. 273 (C), giving a view of the interior 



Fm. 111. Muscular fibres of the uterus. (Sappey.) 

 A, fibres of the uterus of the foetus at term ; B, of a woman twenty years of age ; C, of a woman just delivered, 



of the uterus, shows a triangular cavity, with two cornua, corresponding to the openings 

 of the Fallopian tubes, and exceedingly thick walls, the greatest part of which is com- 

 posed of layers and bands of non-striated muscular fibres. 



The muscular walls of the uterus are composed of fibres of the involuntary variety, 

 arranged in several layers. These fibres are spindle-shaped, always nucleated, the nu- 

 cleus presenting one or two large granules, which have been taken for nucleoli. They 

 are closely bound together, so that they are isolated with great difficulty. In addition to 

 an amorphous adhesive substance between the muscular fibres, we find numerous round- 

 ed and spindle-shaped cells of connective tissue of the variety called embryonic, and a 

 few elastic fibres. The muscular tissue of the uterus is remarkable from the fact that 

 the fibres enlarge immensely during gestation, becoming, at that time, ten or fifteen 

 times as long and five or six times as broad as they are in the unimpregnated state. They 

 are united into bundles, or fasciculi, which, in certain of the layers, interlace with each 

 other in every direction. 



It is quite difficult to follow out the course of the fasciculi of the muscular tissue of 

 the uterus, and the layers of fibres are described somewhat differently by different 

 writers. All agree, however, that there is a superficial layer, tolerably distinct, very 

 thin, resembling the platysma myoides, which is sometimes called the platysma of the 

 uterus. In addition to this layer, we shall describe two, making, in all, three layers, an 

 external, middle, and internal, although this division is somewhat arbitrary. 



