1070 DISSECTION OF THE ABDOMEN AND PELVIS. 



enough of fat ought to be left in the ischio-rectal fossa to protect the levator 

 ani and obturator fascia ; the inferior hsemorrhoidal vessels and nerves may 

 be dissected towards the border of the sphincter (pp. 426 and 672), and the 

 haemorrhoidal branch of the 4th sacral nerve may be seen emerging from be- 

 tween the levator ani and coccygeus muscles (p. 668). The two layers of 

 the superficial fascia in the part of the perinseum anterior to the anus are to 

 be distinguished, the most superficial corresponding to what may most 

 correctly be termed the subcutaneous 4 adipose tissue, and being continued 

 over the ischio-rectal fossa, while the deeper layer terminates behind by 

 dipping deeply in front of that fossa. The most superficial layer having 

 been removed, the blowpipe may be introduced beneath the deep layer in 

 the anterior half of the perinsenm, so that, by inflating the connective tissue 

 underneath it, its external limits, its septum in the middle line, and its 

 continuity forwards may be demonstrated. It may then be slit open, and 

 will be found to be attached to the arch of the pubes externally, to be 

 continuous with the dartos in front, and to be reflected backwards to the 

 triangular ligament behind (p. 259). Underneath it will be found the 

 three long scrotal nerves, viz., the two superficial perineal branches of the 

 pudic and the inferior pudendal branch of the small sciatic nerve, which 

 are to be traced backwards (pp. 670 and 675) : also the superficial and 

 transverse perineal arteries are to be dissected out (p. 426). The muscles 

 on which these structures lie are then to be cleaned, viz., the accelerator 

 urinse embracing the urethra, the erector penis lying upon the crus penis, 

 and the transversalis perinsei (p. 264). In the area between these muscles, 

 subjacent to them, will be observed the triangular ligament or anterior 

 layer of the subpubic fascia, and its relations, especially to the urethra, are 

 to be studied (p. 260). It is then to be divided near the bone, and on its 

 deep aspect the deep transversalis muscle, the constrictor urethrse, and the 

 artery of the bulb are to be dissected. The deep transversalis muscle is to 

 be divided, and Cowper's glands are to be sought for in the middle line 

 beneath (p. 963). On the left side are to be traced out the pudic artery and 

 nerve ; in doing which the branches of the artery to the bulb and the corpus 

 cavernosum should be observed (pp. 425 and 670). Lastly, a good view of 

 the inferior aspect of the prostate gland may be obtained by dividing the 

 sphincter ani from the accelerator urinse muscles at the central point of the 

 perinseum (p. 264). Tn the dissection of the periuseum, constant reference 

 should be made to the bearing of its anatomy on the operations of 

 lithotomy (p. 1039). At this period, the dissectors may remove one of the 

 testicles for the sake of dissecting it while fresh. 



2. Abdominal wall anteriorly. The dissection of the abdominal parietes, 

 in either sex, is to be commenced on the day on which the subject is laid on 

 its back, with a careful examination of the fascia of the inguinal region, on 

 each side, as far as Poupart's ligament. This should, if possible, be under- 

 taken in association with the dissector of the lower limb. An incision is to 

 be made in the middle line from the xiphoid cartilage to the pubes, avoiding 

 the umbilicus, and a transverse one meeting the first, inwards from the 

 anterior superior spine of the ilium. Let the dissector raise the lower of 

 the two flaps of skin thus marked out, remove the subcutaneous layer of fat 

 and fascia, and reflect the deeper layer, usually called superficial fascia, in 

 the same direction as the skin, so as to see the manner in which it is bound 

 down in the line of Poupart's ligament. Let him at the same time observe 

 the superficial epigastric and circumflex iliac arteries and veins, and the con- 

 tinuation of the superficial fascia over the region of the spermatic cord 



