PERINEUM. 



927 



in front of the anus, and extend in an oblique 

 direction backwards and outwards to the point 

 midway between the tuber ischii and the orifice 

 of the gut. In the bilateral operation the first 

 incision is semilunar, the cornua placed at 

 either side between the tuber ischii and the 

 anus, and equidistant from these points respec- 

 tively, the centre situated about three quarters 

 of an inch in front of the anal aperture, and the 

 concavity of the curve directed backwards. 

 For convenience the operator in general begins 

 this incision on the right side of the perineum. 



On removing the integuments the anatomist 

 brings into view anteriorly the superficial fascia 

 of the perineum, surrounding the anus the cuta- 

 neous sphincter, and at either side of the gut a 

 large quantity of adipose cellular tissue, which 

 fills up in great measure the interval between 

 the intestine and the tuber ischii. If the dis- 

 section have been carefully conducted, some ner- 

 vous twigs are also visible near the rami of the 

 ischium and pubis ; they are mostly cutaneous 

 and derived from the sciatic branch of the lesser 

 sciatic nerve (the " perineal cutaneous " of 

 many authors, the " long inferior pudendal " of 

 Scemmering) in its course lo the scrotum and 

 root of the penis. This nerve or its branches 

 are always superficial and liable to injury in 

 many operations performed upon the perineum. 



The superficial fascia. The superficial peri- 

 neal fascia has been by some anatomists de- 

 scribed as two membranes essentially separate 

 and distinct from each other, that nearer to the 

 surface being called the " subcutaneous cellular 

 membrane" of the region, and the deeper of the 

 two being designated " the superficial fascia of 

 the perineum." To the writer this description 

 appears unnecessarily minute, for in fat subjects 

 it is exceedingly difficult to effect such a sepa- 

 ration, and under the most favourable circum- 

 stances the dissection in question is too artificial ; 

 with equal propriety might the superficial fascia 

 of the abdomen be divided into layers, for like 

 that in the perineum, its cutaneous surface is 

 cellular and often loaded with fat, whilst its 

 deeper surface assumes very much an aponeu- 

 rotic appearance. 



The superficial perineal fascia is a cellulo- 

 aponeurotic expansion interposed between the 

 integuments and the principal muscles, &c. of 

 the region, (to this, however, the superficial 

 sphincter muscle, which is absolutely subcuta- 

 neous, forms an exception ;) in the anterior or 

 genito-urinary division of the perineum it is of 

 very considerable thickness, being mostly cellu- 

 lar and fatty superficially, and becoming more 

 dense the deeper the dissection is carried ; nu- 

 merous fibrous bands are interwoven with this 

 expansion, and appear more and more evident 

 the farther from the integument it is examined, 

 so that at length, just like the superficial fascia 

 of the abdomen, it assumes very much the cha- 

 racters of fibrous membrane. The varieties in 

 density which this fascia presents in different 

 subjects are nearly endless ; in corpulent per- 

 sons its grossness is sometimes excessive, and 

 when condensed by inflammation its depth be- 

 comes extreme : this explains the surprising 



distance from the surface to which the surgeon 

 usually cuts in liberating the matter of a peri- 

 neal abscess, and shews the lithotomist the ne- 

 cessity of duly estimating the thickness of this 

 structure before he commences his operation. 

 Traced forwards the superficial fascia becomes 

 gradually thinner until at length it degenerates 

 into cellular membrane continuous almost with- 

 out line of demarcation with the dartos, and as 

 it approaches the scrotum it becomes loose in 

 texture, whilst its cells communicate freely with 

 each other and contain little adipose substance, 

 if any. Followed laterally it seems at first 

 sight to merge gradually into the subcutaneous 

 cellular tissue of the thigh, but when examined 

 from beneath by being raised in a flap from the 

 middle line outwards, it is found to adhere by 

 strong tendinous attachments to the edge of the 

 pelvis, and so powerful is this adhesion that all 

 attempts to pass the handle of a scalpel out- 

 wards between the fascia and the rami of the 

 pubis and ischium uniformly fail. 



In the posterior or anal division of the peri- 

 neum the superficial fascia is little more than a 

 cellular web, appearing, however, somewhat 

 denser in the space between the tuber ischii 

 and the anus; here its continuity with the 

 subcutaneous cellular membrane of the gluteal 

 region may be easily demonstrated, and it also 

 dips in deeply into the ischio-rectal fossa, 

 where its cells become inordinately loaded with 

 fat. If the superficial fascia be carefully raised 

 from before backwards, a deep process of this 

 membrane may be seen to form a partition 

 between the genito-urinary and the anal divi- 

 sions of the perineum. The process referred to 

 constitutes a septum, which, after dipping in 

 deeply behind the transversi perinei muscles, 

 becomes identified with the base of the trian- 

 gular ligament of the urethra ; to demonstrate 

 this connection, however, requires some nicety 

 of manipulation and a suitable subject. In 

 raising this fascia the anatomist cannot fail to 

 observe that its adhesion to the subjacent parts 

 is everywhere extremely loose, except in the 

 situations already specified. 



The peculiar structure and the connections of 

 the superficial perineal fascia afford a satisfac- 

 tory explanation of the course which urinary 

 effusions generally take in the living subject. 

 When urine escapes into the perineum in con- 

 sequence of rupture or ulceration of the ure- 

 thra, provided the solution of continuity be 

 seated superficial to the triangular ligament of 

 the urethra, the liquid makes its way forwards 

 to the scrotum, and after distending that part it 

 proceeds upwards to the abdominal parietes, 

 occasionally reaching the umbilicus, or even 

 attaining to a higher level. The effusion rarely 

 passes downwards along the thighs, or back- 

 wards to the neighbourhood of the anus, and 

 its progress to the surface in the perineum is 

 invariably tedious. In such cases the close 

 adhesion of the superficial fascia to the rami of 

 the pubis and ischium prevents the urine from 

 reaching the thigh ; the connection of the 

 superficial fascia to the base of the triangular 

 ligament of the urethra opposes its progress 



