784 



fascia, the external hemorrhoidal vessels and nerves, and the superficial and trans.- 

 verse perineal vessels ; if the forefinger of the left hand is thrust upwards and 

 forwards into the wound, pressing at the same time the rectum inwards and back- 

 wards, the staff' may be felt in the membranous portion of the urethra. The finger 

 is fixed upon the staffj 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 The knife is then withdrawn, and the forefinger 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 withdrawn, and the position of the stone determined upon, the forceps are intro- 

 duced over the finger into the bladder. If the stone is very large, the opposite 

 side of the prostate should be notched before the forceps is introduced ; the finger 

 is now withdrawn, the blades of the forceps opened, and made to grasp the stone, 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

 are as follows ; the integument, superficial fascia, external hemorrhoidal vessels 

 and nerve, the posterior fibres of the Accelerator urina3, the Transversus perinei 

 muscle and artery (and, probably, the superficial perineal vessels and nerves), the 

 deep perineal fascia, the anterior fibres of the Levator ani, part of the Compressor 

 urethras, the membranous and prostatic portions of the urethra, and part of the 

 prostate gland. 



Fig. 394. A Transverse Section of the Pelvis ; showing the Pelvic Fa.cia. 



AnteriorCruralKerve 



Femoral Yessels~^ 



Internal Pudic 



Parts to be avoided in the operation. In making the necessary incisions in the 

 perineum for the extraction of a calculus, the following rules should be observed: 

 The primary incision should not be made too near the middle line, for fear of 

 wounding the bulb of the corpus spongiosum or rectum ; nor too far externally, 

 otherwise the pudic artery may be implicated as it ascends along the inner border 

 of the pubic arch. If the incisions are carried too far forward, the artery of the 

 bulb may be divided; if carried too far backwards, the entire breadth of the 



