594 BLADDER. LIGAMENTS. 



bladder, and thence ascends to the umbilicus. The false ligaments are 

 folds of peritoneum ; the two lateral correspond with the passage of the 

 vasa deferentia from the sides of the bladder to the internal abdomi- 

 nal rings, and the two posterior with the course of the umbilical arte- 

 ries, to the fundus of the organ. 



The bladder is composed of three coats, an external or serous coat, a 

 muscular, and a mucous coat. The serous coat is partial, and derived 

 from the peritoneum, which invests the posterior surface and sides of 

 the bladder, from about opposite the point of termination of the two 

 ureters to its summit, whence it is guided to the anterior wall of the 

 abdomen by the umbilical ligaments and urachus. The muscular coat 

 consists of two layers, an external layer composed of longitudinal 

 fibres, the detrusor urinae; and an internal layer of oblique and 

 transverse fibres irregularly distributed. The anterior longitudinal 

 fibres commence by four tendons (the tendons of the bladder, or of the 

 detrusor urinae), two superior from the ossa pubis, and two inferior from 

 the rami of the ischia on each side, and spread out as they ascend 

 upon the anterior surface of the bladder to its fundus ; they then con- 

 verge upon the posterior surface of the organ, and descend to its neck, 

 where they are inserted into the isthmus of the prostate gland, and into 

 a ring of muscular tissue, which surrounds the commencement of the 

 prostatic portion of the urethra. Some of the anterior fibres are also 

 attached to this ring. The lateral fibres commence at the prostate 

 gland and the muscular ring of the urethra on one side, and spread out 

 as they ascend upon the side of the bladder to descend upon the 

 opposite side, and be inserted into the prostate and opposite segment 

 of the same ring. Two bands of oblique fibres are described by Sir 

 Charles Bell, as originating at the terminations of the ureters, and 

 converging to the neck of the bladder ; the existence of these muscles 

 is not well established. The fibres corresponding with the trigonum 

 vesicae are transverse. 



It has been shown by Mr. Guthrie,* that there are no fibres at the 

 neck of the bladder capable of forming a sphincter vesica3 ; but Mr. 

 Lanef has described a fasciculus of muscular fibres which surround 

 the commencement of the urethra, and perform such an office. These 

 fibres form a narrow bundle above the urethra, but spread out below 

 behind the prostate gland: they are brought into view by dissecting 

 off the mucous membrane from around the orifice of the urethra. 



Sir Astley Cooper has described around the urethra within the 

 prostate gland, a ring of elastic tissue, or rather, according to 

 Mr. Lane, of muscular fibres, which has for its object the closiire of the 

 urethra against the involuntary passage of the urine. It is into this 

 ring that the longitudinal fibres of the detrusor urinae are inserted, so 

 that this muscle taking a fixed point at the os pubis will not only com- 

 press the bladder, and thereby tend to force its contents along the 



* " On the Anatomy and Diseases of the Neck of the Bladder and of the 

 Urethra " 

 t Lancet, vol. i. 1842-43, p. 670. 



