45*2 TOPOGRAPHICAL ANATOMY. 



The urinary bladder lies, in the female, higher over the perinseum, 

 than in the male. 



The orificium ani is broader, and is placed more posteriorly 

 (behind a transverse line between the tuber ischii] than in the male. 



[Dissection. 1. Of the male perinaeum. 



The subject should be tied up, as in'the operation for lithotomy. The bony 

 boundaries of the perinaeal region must then be carefully recognised. 



Incisions through the skin : 1. A vertical incision is to be made in the raphe 

 from the arch of the pubes, which may be felt, or from the junction of the 

 skin of the perineum with that of the scrotum, to the anterior verge of the 

 anus. 2. Transverse incisions, one on either side from the termination of the 

 last to the outer sides of the tubera ischii. The two triangular flaps thus 

 formed are to be reflected outwards over the thighs, and there fastened. 3. 

 From the anterior verge of the anus carry two incisions, one on either side, 

 around the opening, backwards, until they meet at the posterior verge in the 

 middle line behind ; from this point continue directly downwards to the coc- 

 cyx. These two likewise triangular flaps are to be reflected over the thighs, 

 and there secured. The sphincter ani is now to be dissected, and after exa- 

 mining the posterior portion of the superficial fascia, the ischiorectal fossae of 

 either side may be cleaned out. 



Continuing the dissection of the perineum, make an incision in the middle 

 line as before indicated, from the arch of the pubes, in front, to the anterior 

 extremity of anus, behind, having previously reflected the superficial anterior 

 fibres of the sphincter ani, or even dividing them also in the centre. Now, 

 carefully dissecting the superficial fascia away from its posterior or deeper 

 connexions, examine its relations with the deep perinaeal fascia behind. 

 Having done this, divide the junctions between them, and reflect the layers 

 of the superficial fascia on either side, observing their attachments to the an- 

 terior borders of the rami of the ischia and pubes. 



Care must be taken of the perinasal vessels and nerves which traverse this 

 fascia. The muscles of the perinaeum may now be dissected. 



The accelerator urince should be detached from the deep fascia behind, for 

 it does not arise from it, but is merely applied to its anterior surface. With a 

 little care and dexterity, the handle of the scalpel may be gradually passed 

 between the muscle and the spongy body which it surrounds. The tubular 

 character of the muscle is then clearly demonstrated. The posterior portion 

 of the corp. spongiosum and urethra may even be divided transversely, and 

 then withdrawn from the muscular tube. 



2. Of the female perinaeum. 



The vertical incision should be carried to the anterior commissure of the 

 vagina, and then round the borders of its mouth, meeting at the posterior 

 commissure, terminating in front of the anns. With this variation excepted, 

 as in the male. TRANS.] 



