222 MUSCLES OF THE PERINEUM. 



which demands some degree of delicacy and nice manipulation, a strong 

 light should be thrown upon the part. Having fixed the subject, and 

 drawn the scrotum upwards by means of a string or hook, carry an 

 incision from the base of the scrotum along the ramus of the pubes and 

 ischium and tuberosity of the ischium, to a point parallel with the 

 apex of the coccyx ; then describe a curve over the coccyx to the same 

 point on the opposite side, and continue the incision onwards along 

 the opposite tuberosity, and along the ramus of the ischium and of the 

 pubes, to the opposite side of the scrotum, where the two extremities 

 may be connected by a transverse incision. This incision will com- 

 pletely surround the perineum, following very nearly the outline of its 

 boundaries. Now let the student dissect off the integument carefully 

 from the whole of the included space, and he will expose the fatty 

 cellular structure of the common superficial fascia, which exactly re- 

 sembles the superficial fascia in every other situation. The common 

 superficial fascia is then to be removed to the same extent, exposing 

 the superficial perineal fascia. This layer is also to be turned aside, 

 when the muscles of the genital region of the perineum will be brought 

 into view. 



The ACCELERATORES URINJE (bulbo-cavernosus) arise from a ten- 

 dinous point in the centre of the perineum and from the fibrous raphe 

 of the two muscles. From these origins the fibres diverge, like the 

 plumes of a pen ; the posterior fibres to be inserted into the ramus of 

 the pubes and ischium ; the middle to encircle the corpus spongiosum, 

 and meet upon its upper side ; and the anterior to spread out upon 

 the corpus cavernosum on each side, and be inserted, partly into its 

 fibrous structure, and partly into the fascia of the penis. The poste- 

 rior and middle insertions of these muscles are best seen, by carefully 

 raising one muscle from the corpus spongiosum and tracing its fibres. 



Relations. By their superficial surface with the superficial perineal 

 fascia, the dartos, the superficial vessels and nerves of the perineum, 

 and on each side with the erector penis. By their deep surface with 

 the corpus spongiosum and bulb of the urethra. 



The ERECTOR PENIS (ischio-cavernosus) arises from the rarnus and 

 tuberosity of the ischium, and curves around the root of the penis, to 

 be inserted into the upper surface of the corpus cavernosum, where it 

 is continuous with a strong fascia which covers the dorsum of the 

 organ, the fascia penis. 



Relations. By its superficial surface with the superficial perineal 

 fascia, the dartos, and the superficial perineal vessels and nerve. By 

 its deep surface with the corpus cavernosum penis. 



The COMPRESSOR URETHRA (Wilson's and Outline's muscles), 

 consists of two portions ; one of which is transverse in its direction, 

 and passes inwards, to embrace the membranous urethra ; the other is 

 perpendicular, and descends from the pubes. The transverse portion, 

 particularly described by Mr. Guthrie, arises by a narrow tendinous 

 point, from the upper part of the ramus of the ischium, on each side, 

 and divides into two fasciculi, which pass inwards and slightly up- 



