338 



THE MUSCLES AND FASCIAE OF THE TRUNK. 



other side also, and if injected with sufficient force may reach the front of the 

 abdomen, and travel upwards beneath the superficial fascia ; but it neither passes 

 backwards to the posterior half of the perineum nor downwards upon the thighs. 

 The same course is followed by urine or matter extravasated beneath the proper 

 perineal fascia. 



The deep perineal or subpubic fascia, triangular ligament of the 

 urethra, is stretched across the subpubic arch on the deep surface of the crura of 

 the penis and the bulb of the urethra. It consists of two distinct layers of thin 

 but strong fibrous membrane, separated by intervening structures. The inferior or 

 superficial layer, extending backwards in the middle line to the central point of the 

 perineum, is attached on each side to the rami of the pubis and ischium, while 

 posteriorly its base becomes connected with the superior layer, and with the 

 recurved margin of the superficial perineal fascia. Anteriorly it is continued into 

 the angle between the crura of the penis, and at a deeper level a short fibrous band 



Fig. 297. CORONAL SECTION OF THE PELVIS IN THE SITUATION INDICATED BY THE LINE A, A', IN FIG. 298, 



SHOWING THE DISPOSITION OF THE PELVIC FASCIA AND TRIANGULAR LIGAMENT OF THE URETHRA 

 (SEMIDIAGRAMMATIC). (Gr. D. T.) \ 



a, section of the hip-bone passing through the centre of the acetabulum ; 6, section of the ramus of 

 the ischium ; c, bladder, from which the urethra is continued downwards ; c?, prostate gland ; e, 

 corpus spongiosum urethrae, covered by the bulbo-cavernosi muscles ; f, crus penis, covered by the 

 isehio-cavernosus muscle ; 1, obturator membrane ; 2, obturator internus muscle ; 3, 3, obturator fascia ; 

 4, levator ani muscle ; 5, recto-vesical fascia, dividing into an ascending layer attached to the bladder, 

 and a descending layer forming the sheath of the prostate : between the fascia and the prostate are the 

 veins of the prostatic plexus ; 6, superior, and 7, inferior layer of the triangular ligament of the urethra ; 

 8, constrictor urethrae muscle, embedded in which, close to the ischium, are the pudic vessels and the 

 dorsal nerve of the penis. 



*In order to show more clearly the relations of the parts, the urethra is represented as being laid open 

 through the whole of the prostatic and membranous, and the commencement of the spongy portions ; 

 whereas the lower half of the prostatic portion is naturally a little behind the plane of the section. 



(transverse ligament of the pelvis, Henle) stretches across the subpubic angle near its 

 apex, bounding with the subpubic ligament an oval aperture, through which the 

 dorsal vein of the penis is transmitted. About an inch from the symphysis this 

 layer is perforated by the urethra, immediately before its entrance into the bulb, and 

 the latter structure is intimately adherent to, and receives a superficial expansion 

 from, the under surface of the membrane. It is also pierced on each side of the 

 urethral opening by the artery to the bulb, and a little farther forwards, close to the 

 pubic ramus, by the artery of the corpus cavernosum. Between the two layers of 

 the deep perineal fascia are placed the membranous portion of the urethra, the 



