930 



PERINEUM. 



and the crus penis, posteriorly by the trans- 

 versus perinaei, which constitutes the base of the 

 triangle, whilst the apex is in front where the 

 crus penis and the urethra unite. These spaces 

 are small in the natural condition, but when 

 carefully dissected they become very distinct ; 

 the superficial perineal vessels and nerves 

 traverse them from base to apex ; by separating 

 the accelerator mime from the erector penis 

 the anatomist obtains a view of the triangular 

 ligament of the urethra between these muscles, 

 and he may also form some estimate of its 

 thickness and strength by the touch. 



When the muscles and other structures be- 

 longing to the same layer of parts have been 

 removed, the crura penis along the sides of 

 the region, the urethra in the centre, and the 

 triangular ligament of the urethra stretching 

 across the arch of the pubis, are brought fairly 

 into view; still further back, in the middle 

 line, the recto-urethral triangular space may 

 be partially seen, and also some fibres of the 

 levator ani muscle descending to their insertion 

 from behind the triangular ligament. 



It is unnecessary in this article to describe 

 the crura penis minutely. Each crus adheres to 

 the rami of the ischium and pubis, becoming 

 gradually thicker and larger as it approaches 

 the symphysis, and at length the two crura unite 

 to form the body of the penis; the lateral 

 margins of the triangular ligament of the ure- 

 thra, and the great pudic vessels and nerves in 

 the last part of their course, are overlapped by 

 the crura as they ascend. 



The anatomy of the urethra in respect to 

 catheterism has received the fullest considera- 

 tion already, but the position of the bulb may 

 be now again studied with advantage. This 

 body lies in front of the triangular ligament 

 of the urethra, and projects backwards and 

 downwards towards the rectum ; it is situated 

 about one inch from the anus, and scarcely 

 more than half that distance from the anterior 

 wall of the intestine ; yet the narrow interval 

 between the bulb and the rectum constitutes a 

 portion of the recto-urethral triangular space, 

 through which the early incisions in the bila- 

 teral operation of lithotomy are carried. The 

 bulb is retained in its position by a thin expan- 

 sion derived from the anterior layer of the tri- 

 angular ligament, and continuous with the 

 membrane which invests the corpus spongio- 

 sum urethra. 



Tiie triangular ligament of the urethra (" the 

 deep perineal fascia" of some anatomists, "the 

 perineal ligament" of M. Carcassone, "the 

 middle perineal aponeurosis" of M. Blandin) 

 presents itself next for examination. To expose 

 the superficial surface of this ligament it is only 

 further necessary to detach the crura penis 

 from the bones and to free the bulb from its 

 connections, but to exhibit the deeper surface 

 satisfactorily the dissection must be conducted 

 from within the pelvis. The triangular liga- 

 ment of the urethra extends from the rami of 

 the ischium and pubis at one side to the cor- 

 responding edges of bone on the other; its 

 superficial surface, directed forwards and down- 

 wards, is in contact (so long as the parts remain 



in situ) with the crura penis, the bulb of the 

 urethra, and the muscles already specified ; its 

 posterior surface, directed upwards and back- 

 wards, is related to the prostate gland, the 

 membranous portion of the urethra, Wilson's 

 muscles, and the levatores ani; its base, directed 

 downwards and backwards towards the rectum, 

 gives attachment to the deep process of the 

 superficial perineal fascia, and presents a 

 double curvature, being prolonged in the middle 

 line into a peak, which adheres to the central 

 tendinous point of the perineum ; its apex 

 corresponds to the lower extremity of the sym- 

 physis pubis, and includes the sub-pubic liga- 

 ment between its lamina?, whilst its lateral mar- 

 gins adhere firmly to the rami of the ischium and 

 pubis, and are distinctly continuous with the 

 obturator fascia on either side. The opening " 

 which affords a passage to the urethra is si- 

 tuated about half an inch or rather less above 

 the base of this ligament, and nearly one inch 

 beneath the symphysis pubis, whilst that which 

 transmits the dorsal veins of the penis is placed 

 immediately below the sub-pubic ligament. 

 The triangular ligament possesses uncommon 

 strength ; it serves to fix and to strengthen the 

 urethra and to fill up the arch of the pubis, 

 completing the walls of the pelvis where the 

 bones are deficient, and thus supporting power- 

 fully the abdominal and pelvic viscera. It con- 

 stitutes a perfect partition between the super- 

 ficial and the deep structures in the perineum, 

 dividing the genito-urinary portion of this re- 

 gion into two distinct compartments ; and it 

 consists of two laminae inseparably united to 

 each other in some places, not so in others, 

 for Cowper's glands, the sub-pubic ligament, 

 the arteries of the bulb, the internal pudic 

 vessels in a part of their course, and the so- 

 called muscles of Guthrie, are developed between 

 its layers. 



Cowper's glands may be displayed by the 

 careful removal of the superficial layer of the 

 triangular ligament ; they are two small greyish 

 bodies, each resembling a pea in shape and di- 

 mensions, and placed one on either side be- 

 hind and above the bulb, beneath the mem- 

 branous portion of the urethra, and between the 

 lamina; of the triangular ligament. Their ducts, 

 which open into the urethra in front of the bulb, 

 have been already described. 



Guthrie's muscles, two in number, are situ- 

 ated (according to their discoverer) between the 

 layers of the triangular ligament; each of them, 

 as described by him, arises narrow and tendi- 

 nous from the descending ramus of the pubis 

 near its junction with the ischium, and becom- 

 ing fleshy it passes tranversely inwards, and 

 soon divides into two fasciculi, of which one 

 spreads out on the upper surface and the other 

 on the lower surface of the membranous portion 

 of the urethra. In this manner the muscles 

 from opposite sides meet in a tendinous raphe' 

 on the middle line of the urethra both above 

 and below, the superior raphe heing prolonged 

 from the prostate gland to the junction of the 

 crura penis, and the inferior raphe extending 

 from the prostate to the bulb. Viewed either 

 from above or from below, these muscles are 



