e integument and superficial fascia, we expose the
superficial vessels and nerves, together with the muscles in the
neighbourhood of the urethra and the anus. The accelerator urinae, E,
Fig. 2, Plate 51, which embraces the urethra, and the sphincter ani, B
C, which surrounds the anus, H, occupy the median line, and are divided
each into halves by a central tendon, E B C, which traverses the
perinaeum from before backwards, to the point of the coccyx. On either
side of the anus, in the ischio-rectal space, D D, Fig. 1, Plate 51, is
found a considerable quantity of granular adipose tissue, traversed by
the inferior haemorrhoidal arteries and nerves-branches of the pudic
artery and nerve.

In front of the anus are seen two small muscles (transversae perinaei),
G G, Fig. 2, Plate 51, each arising from the tuber ischii of its own
side, and the two becoming inserted into, B, the central tendon. These
transverse muscles serve to mark the boundary between the anterior and
posterior perinaeal spaces. Behind each muscle is found a small artery,
crossing to the median line. The left transverse muscle and artery are
always divided in the lateral operation of lithotomy. On the outer sides
of the anterior perinaeal space are seen the erectores penis muscles, F
F, overlaying the crura penis. Between each muscle and the accelerator
urinae, the superficialis perinaei artery and nerve course forwards to
the scrotum, &c.

The perinaeal muscles having been brought fully into view, Plate 52,
Fig. 1, their symmetrical arrangement on both sides of the median line
at once strikes the attention. On either side of the anterior space
appears a small angular interval, L, formed between B, the accelerator
urinae, D, the erector penis, and E, the transverse muscle. Along the
surface of this interval, the superficial perinaeal artery and nerve are
seen to pass forwards; and deep in it, beneath these, may also be
observed, L, the artery of the bulb, arising from the pudic, and
crossing inwards, under cover of the anterior layer of the membrane
named the deep perinaeal fascia. The first incision in the lateral
operation of lithotomy is commenced over the inferior inner angle of
this interval.

The muscles occupying the anterior perinaeal space require to be
removed, Fig. 1, Plate 53, in order to expose the urethra, B M, the crus
penis, D, and the deep perinaeal fascia. The fascia will be now seen
stretched across the subpubic triangular space, reach