PARTS CONCERNED IN LITHOTOMY. 847 



and weight, of a calculus in the bladder ; and in the operation for its removal 

 if, as is not unfrequently the case, it should be lodged behind an enlarged pros- 

 tate, it may be displaced from its position by pressing upwards the base of the 

 bladder from the rectum. 



Fig. 459. A View of the Position of the Viscera at the Outlet of the Pelvis. 



Arttry of Corpus Cavernositm 

 Dorsal Artery of Pent* 



Artery of ul&, 

 jfnfefnal fudle Artery- 



Cott-jper't Gland- 



Parts concerned in the Operation of Lithotomy. The triangular ligament must 

 be replaced and the rectum drawn forwards so as to occupy its normal position. 

 The student should then consider the position of the various parts in reference 

 to the lateral operation of lithotomy. This operation is performed on the left 

 side of the perineum, as it is most convenient for the right hand of the operator. 

 A staff having been introduced into the bladder, the first incision is commenced 

 midway between the anus and the back of the scrotum (i. e., in an ordinary 

 adult perineum, about an inch and a half in front of the anus), a little on 

 the left side of the raphe, and carried obliquely backwards and outwards to 

 midway between the anus and tuberosity of the ischium. The incision divides 

 the integument and superficial fascia, the external haBmorrhoidal vessels and 

 nerves, and the superficial and transverse perineal vessels; if the fore-finger of 

 the left hand is thrust upwards and forwards into the wound, pressing at the 

 same time the rectum inwards and backwards, the staff may be felt in the mem- 

 branous portion of the urethra. The finger is fixed upon the staff, and the 

 structures covering it are divided with the point of the knife, which must be 

 directed along the groove towards the bladder, the edge of the knife being 

 carried outwards and backwards, dividing in its course the membranous portion 

 of the urethra, and part of the left lobe of the prostate gland, to the extent of 

 about an inch. The knife is then withdrawn, and the forefinger of the left 

 hand passed along the staff into the bladder ; the staff having been withdrawn, 

 and the position of the stone ascertained, the forceps are introduced over the 

 finger into the bladder. If the stone is very large, the opposite side of the 

 prostate may be notched before the forceps are introduced ; the finger is now 

 withdrawn, and the blades of the forceps opened, and made to grasp the stone, 

 which must be extracted by slow and cautious undulating movements. 



Parts divided in the operation. The various structures divided in this opera- 



