PRACTICAL CONSIDERATIONS : MALE PERINEUM. 1919 



inch above the base of the latter, i.e., about one and a half inches from the anus. 

 (6) Measured in the mid-line from the symphysis to the centre of its base, the tri- 

 angular ligament extends backward about one and a half inches. (7) The mem- 

 branous urethra, lying between the two layers of the triangular ligament, is a little 

 below the middle of this line, i.e. , a little less than an inch below the symphysis and 

 from one-half to three-quarters of an inch above the anus. It measures from one- 

 half to three-quarters of an inch in length. (8) The dorsal vein passes above the 

 triangular ligament a little less than a half inch below the lower margin of the sym- 

 physis ; the pudic artery and nerve pierce the superficial layer of the triangular liga- 

 ment a little lower. (9) The distance from the surface of the perineum to the pelvic 

 floor is about one inch near the symphysis and from two to three inches posteriorly 

 and laterally. (10) The vesical orifice is on a horizontal antero-posterior line drawn 

 through a point a little below the middle of the symphysis, is about an inch to an 

 inch and a quarter behind it, and is from two and a half to three inches above the 



FIG. 1629. 



MR -, 



-Crus penis 



Corpus spongiosum, 



cut Dorsal artery of penis 



Urethra Ischio-cavcrnosus muscle 



Colles's fascia * Artery of corpus cavernosu 



Crus penis- Dorsal nerve of penis 



**/ Compressor urethra muicl. 



Portion of bulb _-- jf9P-' ^-,. 1 Artery of hulb 



Cowper's gland Z^L^Jr s. --Deep transverse perineal 



- " T muscle 



Posterior edge of 



angular ligament ^Sd Dorsal nerve of penis 



Tuber ischii- , . 'Ml Internal pudic artery 



: Sphincter ani 



Internal pudic artery ' ; , <i I vm Bfia5W "ll Perineal division of 



pudic nerve 

 Levator ani 



.Greater sacro-sciatic 

 ligament 



-Coccyx 



Dissection of perineum, in which inferior layer of triangular ligament and corpus spongiosum have been par- 

 tially removed, exposing urethra covered by compressor urethra muscle and Cowper's gland. 



perineal surface. ( 1 1 ) The prostate is about three-quarters of an inch below the 

 symphysis. (12) The pudic artery, as it lies in Alcock's canal, is about one and a 

 half inches above the lower margin of the ischial tuberosity. 



These measurements are, of course, approximate, and vary with the size of the 

 pelvis and its outlet and the amount of subcutaneous fat, which, in the lithotomy 

 position, may much increase the normal antero-posterior convexity of the perineal 

 surface. 



Lateral Lithotomy. It will now be understood that in opening the bladder 

 through one side of the perineum the incision must not extend too far forward, as it 

 might^ involve the artery of the bulb, which lies a little anterior to the "perineal 

 centre" (Fig. 1629) ; or too much externally, as the pudic might be wounded where 

 it lies on the ramus of the ischium ; or too far posteriorly, as, after dividing the 

 layer of the superficial perineal fascia covering the rectal triangle, and thus opening up 

 the ischio-rectal space, it might open the rectum itself. In the deeper parts of the 

 wound it will be seen that if it is too extensive, or carried too far upward, it might 

 pass completely through the left lobe of the prostate and divide the visceral layer of 



