1300 



THE UKO-GENITAL SYSTEM. 



Structure of the Penis. Each corpus cavernosum penis is enclosed by a dense 

 white fibrous coat tunica albuginea corporum cavernosorum, which, fusing with 

 the corresponding coat of the opposite side, forms a median septum penis. The septum 

 is very incomplete, especially near the terminal part of the penis, where it is interrupted 

 by a number of nearly parallel slit- like perforations; hence the term "septum 

 pectiniforme " is often applied to it (Figs. 1019 and 1020). Through these openings the 

 erectile tissue of the corpora cavernosa of opposite sides is continuous. 



The fibrous coat contains some elastic fibres, and may be divided into an outer layer 

 of longitudinally directed fibres and an inner layer of circular fibres, some of which 

 latter are continued into the septum. Numerous fibrous strands, called trabecula 

 corporum cavernosorum, proceed from the deep surface of the tunica albuginea, and 

 stretching across the interior of the corpus cavernosum, form a fine sponge-like framework 

 whose interspaces communicate freely with one another, and are filled with blood. 

 These blood-containing spaces lead directly into the veins of the penis, and, like the veins, 

 have a lining of flat endothelial cells. The size of the penis varies with the amount ofj 

 blood in this cavernous tissue. The structure of the corpus cavernosum urethrse 

 resembles that of the corpora cavernosa penis, but the fibrous coat is much thinner and 

 more elastic, and the trabeculae are finer (Fig. 1019). 



The glans penis is also composed of cavernous tissue which communicates by a rich 

 venous plexus, situated on the ventral aspect of the urethra, with the corpus spongiosum 

 urethrse. No strongly marked tunica albuginea is present, and the erectile tissue is 

 practically bounded by the firmly adherent skin. Surrounding the urethra, which in this 

 part of the penis is represented by a laterally compressed slit -like passage, is a mass of 

 fibre-elastic tissue which forms a kind of median septum within the glans. This septum 



Dorsal vein 

 Dorsal artery | Dorsal nerve 



Corpus cavernosum 

 penis 



Corpus cavernosurn 

 urethrae 



Glans peni 



Corpu 

 penis 



s cavernosum 



Septum 

 pectiniforme 



Urethra 



FIG. 1019. TRANSVERSE SECTION THROUGH THE 

 BODY OP THE PENIS. 



Urethra 



FIG. 1020. A LONGITUDINAL SECTION OF THE 

 TERMINAL PORTION OF THE PENIS. 



is continued backwards to join the sheath of the conical end of the corpora cavernosa, an 

 ventrally it gives attachment to the frenulum of the prepuce. It imperfectly divides the 

 erectile tissue of the glans into right and left portions, which, however, freely communicai 

 dorsally. From the septum, trabeculse pass out in all directions into the tissue of the glam 



Loosely surrounding the corpora cavernosa penis and the corpus cavernosum urethi 

 is a fibrous sheath containing numerous elastic tissue fibres. This sheath is termed 

 fascia penis, and reaches as far as the base of the glans, where it becomes fixed to the 

 floor of the groove limited by the corona glandis. In its proximal part the sheath give 

 insertion to many of the fibres of the bulbo-cavernosus and ischio-cavernosus muscles. 



Superficial to the fascia penis is a layer of extremely lax areolar tissue, and E 

 superficial still is a prolongation of the tunica dartos of the scrotum, covered by 

 delicate skin of the penis. Numerous sebaceous glands are present in the skin 

 especially on the urethral aspect of the penis. 



In some mammals, such as the walrus, dog, bear, baboon, etc., a bone called the os penis it 

 developed in the septum which intervenes between the corpora cavernosa penis. 



Vessels and Nerves of the Penis. The penis receives its arterial supply from branches 

 the internal pudendal artery. The erectile tissue of the corpora cavernosa penis is supplie 

 chiefly by the deep arteries of the penis, while that of the corpus cavernosum urethrae receives ife 

 arterial supply from the artery to the bulb. Branches of the dorsal artery of the penis piercir 

 the fibrous coat of the corpora cavernosa penis furnish additional twigs to the erectile tissue 

 these structures. The glans receives its chief blood-supply from branches of the dorsal art" 

 The small branches of these arteries run in the trabeculae of the erectile tissue, and 

 capillaries, into which they lead, open directly into the cavernous venous spaces. As the 

 lie in the finer trabeculae the smaller branches often present a peculiar twisted apj 

 and hence the name arterise helicinae is sometimes applied to them. 



