1262 



UROGENITAL SYSTEM 



bon}^ attachments and begins posteriorly in the superficial perineal interspace 

 with an enlargement, the bulb [bulbus urethras] (fig. 1023), whose posterior surface 

 rests on the superficial fascia of the urogenital trigone and is enclosed by the m, 

 bulbo-cavernosus. Anteriorly the bulb gradually tapers to a rather slender 

 cylindrical portion, the body, very uniform in diameter, which extends throughout 

 the entire length of the bodj^ of the penis, lying in the median line beneath the 

 fused corpora cavernosa penis (figs. 1022, 1023). At the neck of the penis it 

 undergoes a sudden enlargement to form the glans, the whole of that structure, 

 which has already been described, being formed by the corpus cavernosum 

 urethrsB. The structure of the corpus cavernosum urethrse is essentially the same 

 as that of the corpora cavernosa penis, the tunica albuginea, however, being much 

 thinner. 



Vessels and nerves. — The principal arterial supply of the penis is derived from the internal 

 pudendal artery (see p. 610), although the proximal portion of its integument is also supphed 

 by the external pudendal branches of the femoral artery. The veins from the integument 



Fig. 1024. — Mid-sagittal Section (diagrammatic) Showing Male Bladder, Urethra, etc. 



Symphysis pubis, 



Subpubic lig. 



Suspensory lig. 



Urogenital trigone 



(.diaphragm) 



Corpus cavernosum 

 urethrae 



Corpus cavernosum 

 penis 



Glans penis 



Prepuce 



Fossa navicularis 



Bladder 



Seminal vesicle 

 Ampulla 



Prostate middle lobe 

 Ejaculatory duct 

 Prostatic utriculus 



Prostate gland 



Bulbo-urethral 

 (Cowper's) gland 

 Ductus deferens 



Epididymis 



Testis 



Scrotum 



collect into one or more stems, the superficial dorsal veins, which run along the dorsal mid-line 

 and, diverging, open into the great saphenous vein. The deep veins from the corpora cavernosa 

 open into a median deep dorsal vein, which connects partly with the internal pudendal veins 

 and partly with the pudendal plexus. Both the superficial and deep lymphatics terminate in 

 the superficial inguinal nodes. The lymph-vessels from the glans are said to follow those of.the 

 urethra and end in the deep ingviinal and external iliac nodes. 



The nerves supplying the penis arc llie anterior scrotal branches of the ilio-inguinal and the 

 perineal branches and dorsal nerve of the penis from the pudendal. Sympathetic fibres also 

 pa.ss to the penis from the hyf)ogastric plexus and with these fibres from the third and fourth 

 sacral nerves, wliicli constitutes what is termed the nervus erigens, since stinuilation of it pro- 

 duces erection of the organ. An aiiatonii<;al provision for the production of tliis i)hcnomenon has 

 been found in the occurrence of peculiar thickenings of the intima of the arteries of the penis, 

 by which the lumina of the ve.sstsls are greatly diminished or even occluded when in a state 

 of moderate contraction, as when the organ is flaccid. When the arteries are dilated the intimal 

 thickenings become reduced in lieight and th(! blood is aiTorded a free passage into the lacunar 

 spaces of the corpora cavernosa, which thus become engorged. 



4. The Male Urethra 



Tlio urethra is the canal which extends from the bladder to the extremity of 

 the glans penis and serves for the passage of both the urine and the seminal fluid. 



