PERINEUM. 
The transversalis perinei artery is of small 
Size; it springs from the internal pudic, a little 
anterior to the source of the superficial perineal 
artery, but these two vessels not unfrequently 
arise by a single common trunk. The trans- 
versalis perinei artery passes through the obtu- 
rator fascia, and often perforates the base of 
the triangular ligament of the urethra ; it quickly 
becomes superficial, applying itself to the cuta- 
neous surface, and running usually near the 
posterior edge of the transversus perinei mus- 
cle, it thus gains the central tendinous point 
of the perineum, where it anastomoses with 
the inferior hemorrhoidals from behind, the 
transversalis and superficialis perinei arteries 
from the opposite side, and with the neigh- 
bouring superficial perineal. This vessel is 
accompanied by two veins and by one or more 
branches of the superficial division of the 
pudic nerve. 
The accelerator urine muscle (the ejaculator 
seminis of some anatomists, the bulbo-caver- 
nosus of others) extends from the central ten- 
dinous point of the perineum forwards along 
the urethra, being identified with the correspon- 
ding muscle of the opposite side in a raphé 
which occupies the middle line; and so inti- 
mate is this connection that both might be 
conveniently described together as a single 
muscle. The fibres of the accelerator urine 
spring from the side of the raphé, and pass 
from thence outwards and upwards upon the 
urethra. The anterior fibres incline very ob- 
liquely forwards and outwards to arrive at 
the surface of the corpus cavernosum penis, 
where they terminate. In consequence of this 
disposition the acceleratores urine muscles 
are separated from each other in front by a 
Y-shaped interval in which the urethra appears. 
The succeeding fibres, after embracing the 
urethra laterally, are lost on a short horizontal 
tendon, which likewise receives the correspond- 
ing fibres of the opposite muscle. This tendon 
is placed above the urethra, beneath the junction 
of the crura penis, and anterior to the triangular 
ligament of the urethra. The posterior fibres 
incline outwards more than the others, and are 
inserted into the superficial surface of the 
triangular ligament of the urethra, many of 
them extending nearly to the crus penis. The 
accelerator urine muscle lies on the bulb and 
the neighbouring portion of the corpus spongi- 
osum. In conjunction with its fellow it con- 
stitutes a fleshy sheath, all but perfect, for the 
urethra. Its action is to compress the canal, 
and at the same time to draw forwards the 
bulb. It is employed in expelling the semen 
and the last drops of urine from the sinus of 
the bulb; and by contracting spasmodically it 
May even arrest the progress of a catheter, an 
occurrence explained by the manner in which 
“many of its fibres completely surround the 
passage. 
_ The erector penis muscle (called sometimes 
“the compressor penis,” or “ the ischio-caver- 
hosus,”) is placed obliquely along the lateral 
“Margin of the genito-urinary division of the 
perineum, where it partially envelopes and 
conceals from view the corresponding crus 
VOL. III. 
929 
penis. It is elongated, broader in the centre 
than at the extremities, and curved so as to 
embrace the crus on which it is moulded. 
The erector penis springs by a narrow tendi- 
nous attachment from the inner surface of the 
tuber ischii, and from the extremity of the great 
sciatic ligament beneath the transversus perinei 
muscle; the fleshy fibres soon succeed, and 
after continuing in an oblique direction up- 
wards, forwards, and inwards, they end in 
a fibrous expansion which inclines outwards 
and forwards to terminate by two processes on 
the surface of the corpus cavernosum penis. 
Anatomists are not agreed on the action of this 
muscle: it may serve to draw down and to 
compress the crus penis, and in that manner to 
influence the circulation therein, but it can 
have no direct concern in causing the erection 
of the organ. 
The transversus perinei muscle (“the ischio- 
perineal” of some anatomists) passes from the 
tuber ischii to the central tendinous point of 
the perineum ; in this course the muscle in- 
clines forwards and slightly downwards, so that 
its direction is not exactly transverse. It is 
attached externally to the inside of the tuber 
ischii, above the origin of the erector penis and 
the crus penis; and internally it is confounded 
with the several muscles already specified as 
reaching the central tendinous point. The 
transversus perinei is often of a triangular 
shape, the base at the ischium, and the apex 
at the central tendinous point of the perineum ; 
it is mostly fleshy, except at its insertion, which 
is aponeurotic. This muscle is exceedingly 
uncertain as regards its developement, being 
sometimes replaced by a few scattered fibres 
derived apparently from the levator ani, and 
occasionally reinforced by a second muscle, 
termed the transversus perinei alter. The 
transversus perinei alter, when present, lies 
anterior and superior to the other, and extends 
from the ramus of the ischium to the bulb, 
where it becomes confounded with the accele- 
rator urine. The transversus perinei is related 
by its superficial surface to the superficial peri- 
neal fascia, the superficial perineal and the 
transverse perineal vessels and nerves, the inser- 
tion of the superficial sphincter ani, and the 
origin of the erector penis and the crus penis. 
Its deep relations are the levator ani and Wil- 
son’s muscles, together with the triangular 
ligament of the urethra. The transversus peri- 
nei contributes to the strength of the perineum 
by raising and fixing the central tendinous 
point ; it also assists the levator ani in raising 
and supporting the rectum and the pelvic vis- 
cera. ‘The transversi perinei muscles have been 
by some described as a single digastric muscle, 
semilunar in shape, and with the concave mar- 
gin directed backwards and upwards towards 
the gut; the result of the simultaneous action 
of these two bellies would be to raise and 
compress the intestine in front, and thus to 
assist in completing the process of defecation. 
The triangular spaces are situated one at 
either side of the urethral prominence; each is 
bounded internally by the accelerator urine 
and the urethra, externally by the erector penis 
30 
