PERINEUM. 
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 
Semmering) in its course to 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- 
cters 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 
927 
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 wansversi 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 
