DISSECTION OF THE PERINEUM IN THE MALE. '2q6 



the ischial arch, the intra-pelvic urethra becomes directly continuous 

 with the extra-pelvic portion, and from the point of continuity onwards 

 the urethra is enveloped in a sheath of erectile tissue, which is the 

 corpus spongiosum. The corpus spongiosum forms at either of its 

 extremities an enlargement. The posterior enlargement, which is 

 situated at the ischial arch, is termed the bulb; the anterior enlarge- 

 ment is the glans 2)enis. The glans forms the expanded free extremity of 

 the penis, and it surrounds the blunt anterior end of the united corpora 

 cavernosa. During erection the enlargement assumes a shape resem- 

 bling, somewhat, the rose of a watering-can, having a prominent ridge — 

 the corona glandis, behind which there is a slight constriction — the 

 cervix. The front of this rose-like swelling presents a fossa from which 

 the urethra projects for about half an inch as a free tube — the urethral 

 tube. Above the base of the urethral tube there is the opening of a 

 double cavity — the urethral sinus, which generally contains some of the 

 partially inspissated secretion of sebaceous glands that open into the 

 cavity. Inferiorly the corona glandis is interrupted on the middle line 

 by the suburethral notch. 



The corpus spongiosum as far as the glans is surrounded by the 

 accelerator urinse muscle. Superiorly it fits into the groove on the 

 lower aspect of the corpora cavernosa, and along its under aspect pass 

 the retractor muscles of the penis. 



Directions. — Immediately in front of the junction of its crura, the 

 penis should now be amputated, that the structure of its component 

 parts may be examined. 



Structure of the corpora cavernosa. The corpora cavernosa possess 

 a strong envelope of white fibrous tissue, termed the tunica albuginea. 

 This tunica albuginea, besides forming a common envelope to the united 

 bodies, sends inwards an incomplete mesial septum between the two — 

 the septum pectiniforme. This septum when viewed laterally is seen to 

 be perforated by numerous vertical slits, which give its processes a 

 resemblance to the teeth of a comb ; hence the name. Besides the sep- 

 ti;m pectiniforme, numerous small trabeculse pass into the interior of the 

 corpora cavernosa, and by their anastomosis form a framework for these 

 bodies. The trabecule are composed of fibrous tissue with some bundles 

 of non-striped muscular tissue. Between the trabeculse are innumer- 

 able intercommunicating spaces, placed between the capillaries and the 

 small veins. During erection the blood is poured into these spaces, 

 and thus is brought about the increase in the size of the organ. At 

 other times the blood passes in the ordinary manner from the capillaries 

 to the venous radicles. In the crura and peripheral part of the 

 cavernous bodies some of the small arteries terminate directly in 

 these venous spaces. The small arteries are imbedded in the 

 trabeculse, and when these are contracted, in the non-erect state, the 



