THE FEMALE PERINsEUM. 1069 



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 perinaeum about an inch and a half in front of 

 the anus) a little on the left side of the raphe, and carried obliquely backward and outward to 

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

 and superficial fascia, the inferior hsemorrhoidal vessels and nerves, and the superficial and trans- 

 verse permeal vessels. If the forefinger of the left hand is thrust upward and forward into 

 the wound, pressing at the same time the rectum inward and backward, the staff may be felt in 

 the membranous 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 toward 

 the bladder, the edge of the knife being turned outward and backward, 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 The knife is then withdrawn, and the forefinger of the left hand 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 position of the stone having been ascertained, the 

 staff is to be withdrawn, and the forceps is introduced over the finger into the bladder.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 is intro- 

 duced : the finger is now withdrawn, and the blades of the forceps opened and made to grasp 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 operation are as 

 follows : the integument, superficial fascia, inferior hsemorrhoidal vessels and nerves, and prob- 

 ably the superficial perineal vessels and nerves, the posterior fibres of the Accelerator urinse, the 

 Transversus perinaei muscle and artery, the triangular ligament, 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. 



Parts to be Avoided in the Operation. In making the necessary incisions in the peri- 

 naeum for the extraction of a calculus the following parts should be avoided : The primary incis- 

 ion should not be made too near the middle line, for fear of wounding the bulb of the corpus 

 spqngiosum or the 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 backward, the entire breadtli 

 of the prostate and neck of the bladder may be cut through, which allows the urine to become 

 infiltrated behind the pelvic fascia into the loose areolar tissue between the bladder and rectum, 

 instead of escaping externally ; diffuse inflammation is consequently set up, and peritonitis, from 

 the close proximity of the recto-vesical peritoneal fold, is the result. If, on (lie contrary, only 

 the anterior part of the prostate is divided, the urine makes its way externally, and there is 

 less danger of infiltration taking place. 



During the operation it is of great importance that the finger should be passed into the 

 bladder before the staff is removed ; if this is neglected, and if the incision made in the prostate 

 and neck of the bladder is too small, great difficulty may be experienced in introducing the 

 finger afterward ; and in the child, where the connections of the bladder to the surrounding 

 parts are very loose, the force made in the attempt is sufficient to displace the bladder upward 

 into the abdomen, out of the reach of the operator. Such a proceeding has not unfrequently 

 occurred, producing the most embarrassing results and total failure of the operation. 



It is necessary to bear in mind that the arteries in the perinaeum occasionally take an abnor- 

 mal course. Thus the artery of the bulb, when it arises, as sometimes happens, from the pudic 

 opposite the tuber ischii, is liable to be wounded in. the operation for lithotomy in its passage 

 forward to the bulb. The accessory pudic may be divided near the posterior border of the pros- 

 tate gland, if this is completely cut across ; and the prostatic veins, especially in people advanced 

 in life, are of large size, and give rise, when divided, to troublesome haemorrhage. 



THE FEMALE PERINEUM. 



The female perinaeum presents certain differences from that of the male, in 

 consequence of the whole of the structures which constitute it being perforated 

 in the middle line by the vulvo-vaginal passage. 



The superficial fascia, as in the male, consists of two layers, of which the 

 superficial one is continuous with the superficial fascia over the rest of the body, 

 and the deep layer, corresponding to the fascia of Colles in the male, is like it 

 attached to the ischio-pubic ramus, and in front is continued forward through 

 the labia majora to the inguinal region. It is of less extent than the male, in 

 consequence of being perforated by the aperture of the vulva. 



On removing this fascia the muscles of the female perinaeum, which have 

 already been described (page 374), are exposed. The Sphincter vaginae, corre- 

 sponding to the Accelerator urinae in the male, consists of an attenuated plane of 

 fibres, forming an orbicular muscle around the orifice of the vagina, instead of 

 being united in a median raphe, as in the male. The Erector clitoridis is propor- 

 tionately reduced in size, but differs in no other respect, and the Transversus 

 perinasi is similar to the muscle of the same name in the male. 



