Part 37 (1/2)

A B. The perinaeal raphe.

C. The place of the coccyx.

D D. The projections of the ischiatic tuberosities.

BE. The line of section in lithotomy.

[Ill.u.s.tration: Legs and s.c.r.o.t.u.m, showing bone, blood vessels and other internal organs.]

Plate 50; Figure 2, Figure 3, Figure 1.

PLATE 51.

FIGURE 1.

A. The superficial fascia covering the urethral s.p.a.ce.

B. The sphincter ani.

C. The coccyx.

D D. The right and left ischiatic tuberosities.

H. The a.n.u.s.

I I. The glutei muscles.

FIGURE 2.

A, B, C, D, H, I. The same parts as in Fig. 1.

E. The accelerator urinae muscle.

F F. Right and left erector p.e.n.i.s muscle.

G G. Right and left transverse muscle.

[Ill.u.s.tration: Abdomen, showing bone, blood vessels and other internal organs.]

Plate 51; Figure 2, Figure 1.

COMMENTARY ON PLATES 52 & 53.

THE SURGICAL DISSECTION OF THE DEEP STRUCTURES OF THE MALE PERINAEUM.

THE LATERAL OPERATION OF LITHOTOMY.

The urethra, at its membranous part, M, Fig. 1, Plate 53, which commences behind the bulb, perforates the centre of the deep perinaeal fascia, E E, at about an inch and a half in front of F, the a.n.u.s. The anterior layer of the fascia is continued forwards over the bulb, whilst the posterior layer is reflected backwards over the prostate gland.

Behind the deep perinaeal fascia, the anterior fibres of K, the levator ani muscle, arise from either side of the pubic symphysis posteriorly, and descend obliquely down wards and forwards, to be inserted into the sides of N N, the r.e.c.t.u.m above the a.n.u.s. These fibres of the muscle, and the lower border of the fascia which covers them, lie immediately in front of the prostate, C C, Fig. 2, Plate 53, and must necessarily be divided in the operation of lithotomy. Previously to disturbing the lower end of the r.e.c.t.u.m from its natural position in the perinaeum, its close relation to the prostate and base of the bladder should be noticed. While the a.n.u.s remains connected with the deep perinaeal fascia in front, the fibres of the levator ani muscle of the left side may be divided; and by now inserting the finger between them and the r.e.c.t.u.m, the left lobe of the prostate can be felt in apposition with the forepart of the bowel, an inch or two above the a.n.u.s. It is owing to this connexion between these parts that the lithotomist has to depress the bowel, lest it be wounded, while the prostate is being incised. If either the bowel or the bladder, or both together, be over-distended, they are brought into closer apposition, and the r.e.c.t.u.m is consequently more exposed to danger during the latter stages of the operation. The prostate being in contact with the r.e.c.t.u.m, the surgeon is enabled to examine by the touch, per anum, the state of the gland. If the prostate be diseased and irregularly enlarged, the urethra, which pa.s.ses through it, becomes, in general, so distorted, that the surgeon, after pa.s.sing the catheter along the urethra as far as the prostate, will find it necessary to guide the point of the instrument into the bladder, by the finger introduced into the bowel. The middle or third lobe of the prostate being enlarged, bends the prostatic part of the urethra upwards. But when either of the lateral lobes is enlarged, the urethra becomes bent towards the opposite side.