298 Anatomy Applied to Medicine and Surgery. 



surface, and, when found, the knife is slipped along the 

 finger until it reaches the groove and is then pushed along 

 it until the bladder is reached. As the knife is withdrawn, 

 its edge is turned downwards and outwards, so as to en- 

 large, obliquely, the opening made in the neck of the blad- 

 der and prostate. The finger now follows the staff into 

 the bladder, the staff is removed, the stone identified, the 

 lithotomy forceps introduced along the finger and the) 

 stone seized and withdrawn. The first incision cuts the 

 skin and fasciae ; the transverse perineal artery, nerve and 

 vein ; the lower edge of the upper layer of the triangular 

 ligament and the external hemorrhoidal vessels and 

 nerves. The second incision divides the membranous and 

 prostatic portions of the urethra ; the posterior portion of 

 the triangular ligament ; the compressor urethras ; the lev- 

 ator ani and the left lateral lobe of the prostate. 



The following structures may be injured if care be not 

 taken to avoid them : 1. The artery of the bulb. This is 

 avoided by not starting the incision beyond the point 

 mentioned, i.e., beyond a point, one and a quarter inches 

 in front of the centre of the anus, since the artery runs 

 towards the central tendinous point, which is about one 

 and a half inches in front of the centre of the anus. 2. 

 If the incision be carried too far outwards the internal 

 pudic vessels, which lie inside the tuberosity of the isch- 

 ium, might be wounded. 3. Rectum. If the incision be 

 not carried sufficiently outwards, or if the rectal tissues be 

 not guarded with the finger, or if the bowel be distended, 

 then the rectum would be in danger of being wounded. 



Prostate. If the prostate be not incised in a direction 

 downwards and outwards, i.e., if it be cut transversely, 

 then it is probable that the recto-vesical fascia, which 

 passes from the sides of the pelvis to the prostate gland 

 will be opened up, and infiltration of urine into the pelvic 

 cavity occur. 



