THE UKINAKY BLADDER 1283 



the fold of the opposite side across the median plane, behind the posterior border of 

 the bladder and the ductus deferentes. These folds represent the plicae rectouterinse 

 or folds of Douglas in the female, and are to be regarded as connexions of the ductus 

 deferentes rather than of the bladder ; hence the term sacro-genital folds is applicable 

 to these structures in both sexes. The folds are seen in Figs. 990 and 995. 



The peritoneum covering the upper surface of the empty or partly distended bladder 

 often exhibits a transversely disposed fold or wrinkle, to which the term plica vesicalis 

 transversa has been applied. This fold, when well developed, can be traced on to the 

 side wall of the pelvis, where it traverses the paravesical fossa, and in some cases it is 

 found to cross the pelvic brim and to be directed towards the abdominal inguinal ring 

 (Fig. 995). 



In the female the peritoneum is reflected posteriorly from the upper surface of 

 the bladder on to the anterior aspect of the uterus. 



Fixation of the Bladder. When the ligamentum umbilicale medium, or fibrous 

 cord of the urachus, which binds the bladder apex to the anterior abdominal wall, 

 and the peritoneal folds, already described as the false ligaments, are severed, the 

 bladder is easily moved about, except in its lower and basal parts. Anteriorly it 

 is connected to the pubis, and laterally to the fascial lining of the pelvis by loose 

 areolar tissue only, which permits free movement during expansion and contraction. 

 The lower fixed part of the bladder is held in place chiefly by processes of the 

 pelvic fascia, continuous with those forming the sheath of the prostate. The 

 fascial connexions constitute the true ligaments of the bladder, and are described 

 as pubo -pro static or anterior ligaments, reaching the bladder from the pubis in front, 

 and lateral ligaments, reaching the bladder from the fascial lining of the side wall 

 of the pelvis. 



In addition to the urachus and the peritoneal and the true ligaments already 

 mentioned, the bladder is supported and fixed in position, in the region of its 

 basal surface, by the dense fibrous and unstriped muscular tissue which surrounds 

 the seminal vesicles, the terminal portions of the ductus deferentes and the ureters. 



Laterally the strands of connective tissue and the bundles of muscle fibres forming this sup- 

 port pass backwards and are continued into the fascia which surrounds the branches of the 

 hypogastric artery. Muscle fibres connected with the bladder wall are also found within the 

 pubo-prostatic ligaments, through which they are attached to the pubis. 



In the female the basal part of the bladder wall is supported and held in place 

 by its connexion with the anterior wall of the vagina. The region of the urethral 

 orifice is the most firmly fixed part of the bladder wall in both sexes. 



Structure of the Bladder Wall. The wall of the bladder from without inwards 

 is composed of a serous, a muscular, a submucous, and a mucous coat. The tunica serosa 

 or serous coat, formed by peritoneum, is incomplete, and covers only the upper and 

 posterior parts of the distended bladder (Fig. 993). 



A considerable amount of fibrous connective tissue surrounds the tunica muscularis 

 or muscular coat, and penetrating it, divides it into numerous coarse bundles of muscle 

 fibres. All the muscle fibres are of the unstriped variety, and the bundles which they 

 Form are arranged in three very imperfectly separated strata called external, middle, 

 'j-nd internal. The stratum externum is for the most part made up of fibres which are 

 iirected longitudinally, and it is best marked near the median plane on the upper and under 

 ispects of the bladder. Farther from the median plane, on the sides of the bladder, the 

 ibres composing the external stratum run more obliquely, and their directions frequently 

 iross one another. In the male, many of the fibres of the external stratum are attached 

 30th anteriorly and posteriorly to the prostate, and in the female the corresponding fibres 

 oin the dense tissue which in this sex forms the upper part of the wall of the urethra. 

 3ther fibres of this stratum on each side of the body join the lower part of the symphysis 

 mbis and constitute the musculus pubo vesicalis, which lies in the substance of pubo- 

 )rostatic ligament. Lastly some fibres of the external stratum blend posteriorly with the 

 ''interior aspect of the rectum and receive the name of musculus rectovesicalis. The 

 itratum medium is composed of fibres which for the most part run circularly, and 

 orms the greater part of the thickness of the muscular coat. In the region of, and 



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