476 UTERUS, BY DR. R. CHROBAK. 



the uterus is composed, and is recognized by its remarkably 

 large and, during pregnancy, thick- walled vessels. 



The innermost layer, which, according to Luschka,* is to be 

 regarded as the most important of all, since it exhibits traces 

 of the early division of the uterus into two lateral halves, is 

 essentially composed of circular fibres, which, proceeding from 

 the circular fibre layer of the uterine portion of the Fallopian 

 tubes, forms successively larger annuli that meet in the middle 

 line, and not only form the foundation of the body of the uterus, 

 but can be traced into the cervical region, and from thence into 

 the vagina. (The so-called internal and external sphincters of 

 the os uteri belong to this circular fibre layer.) Besides this 

 well-marked circular layer, a triangular layer of longitudinal 

 fibres is present on the anterior and posterior wall of the 

 uterus, f the apex of the triangle being directed downwards ; 

 from this delicate muscular fasciculi can be traced into the 

 mucous membrane. 



The regular arrangement of the fibres described above is less 

 observable in the cervical region of the uterus,J where they 

 are grouped into about three layers (Henle). The circular 

 fibres of the innermost layer of the body form by far the 

 largest middle layer, which is bounded externally by longitu- 

 dinal fibres that are in great part lost in the vicinity of the 

 bladder, vagina, and urethra, whilst the innermost layer is 

 likewise composed of longitudinal muscular fibres that sup- 

 ply the mucous membrane with fibres, and interweave at 

 the os externum and internum with the circular fibre 

 layers forming the sphincters. According to Guyon, the 

 sphincter of the os internum forms an isthmus three milli- 

 meters in length. 



All these layers of the uterus are for the most part composed 

 of contractile fibre cells, so firmly united into fasciculi and flat 

 muscular expansions by means of a strong cementing material 



* Luschka, loc. cit. 



t Helie, loc. cit. 



J Retzius, Struldur des Uterus, in Froriep's Tagesbericht, in Canstatt's 

 Jahresbericht, Band i. , p. 64, 1850. 



Guy on, Etude sur la cavite de V Uterus a I'etat de vacuite, Journal de 

 Physiologic, Tom. ii. 



