MUSCULAR TISSUE OF THE UTERUS. 475 



The principal portion of the substance of the uterus is com- 

 posed of unstriated muscular fibres which are simply super- 

 imposed on one another in a succession of layers ; but since even 

 in the pregnant uterus it is not practicable to dissect off the 

 several layers separately, considerable confusion prevails in 

 regard to their arrangement and subdivision. 



If the development of the layers be followed, we may reduce 

 the number of layers to three ; an internal, chiefly consisting 

 of circular fibres; a middle, in which the fibres run for the 

 most part longitudinally ; and an external accessory layer. 



The external layer, which is situated immediately beneath 

 the peritoneum, and is intimately connected with it, is by far 

 the thinnest, but at the same time is the most distinct and 

 independent; it is prolonged upon the adnexa of the uterus. 

 This external layer is chiefly formed of a fasciculus of longi- 

 tudinal fibres on the posterior wall of the uterus arising from 

 the margin of the cervix,* though these fibres pass to enter 

 into its formation from the sides of the uterus, and it then 

 spreads over the organ as far as to the round ligaments. 



The second layer, separated from the foregoing by many 

 transverse fasciculi, is composed of numerous strong muscular 

 fasciculi,")* extending from behind forward over the fundus; and 

 these again, diverging anteriorly and posteriorly, decussate fre- 

 quently with other short fibres. Near the middle of the fundus 

 this muscular layer fuses to a certain extent with the superficial 

 one.J Beneath this, which is the last distinctly recognizable 

 layer, and which, like that above mentioned, does not cover the 

 sides of the uterus, are a number of tolerably strong smooth 

 and short fasciculi, pursuing for the most part a circular course, 

 which decussate at the most diverse angles, give off a few 

 processes to the ligaments, and run in such a manner that, 

 speaking broadly, those which are superficial in front dip into 

 the deeper part of the uterus posteriorly, and vice versa. 



This layer is by far the most important of all those of which 



* Helie, Recherches sur la disposition des Fibres musculaires de V Uterus. 

 Paris, 1869. 



t Pappenheim, Vorlaufige Mittheilung. Korn and Wunderlich's Viertel 

 jahrschrift, 3 Jahre, Heft. i. 



Helie, loc. cit. 



