536 URETHRA. 



by a peculiar reddish fibrous substance. They receive their blood 

 from the capillaries of the arteries in the same manner with veins 

 generally, and not by means of vessels having a peculiar form and 

 distribution, as described by Muller. The helicine arteries of that 

 physiologist have no existence.* 



Vessels and Nerves. The arteries of the penis are derived from 

 the internal pudic ; they are, the arteries of the bulb, arteries of the 

 corpus cavernosum, and dorsalis penis. Its veins are superficial and 

 deep. The deep veins run by the side of the deep arteries, and ter- 

 minate in the internal pudic veins. The superficial veins emerge in 

 considerable number from the base of the glans, and converge on 

 the dorsum penis, to form a large dorsal vein, which receives other 

 veins from the corpus cavernosum and spongiosum in its course, and 

 passes backwards between two layers of the ligamentum suspen- 

 sorium, and throiigh the deep fascia beneath the arch of the os pubis, 

 to terminate in the prostatic and vesical plexuses. 



The Lymphatics terminate in the inguinal glands. The nerves are 

 derived from the internal pudic nerve, from the sacral plexus, and, 

 as shown by Professor Muller in his beautiful monograph, from the 

 hypogastric plexus. 



URETHRA. 



The urethra is the membranous canal extending from the neck 

 of the bladder to the meatus urinarius. It is sigmoid in its course, 

 and is composed of two layers, a mucous coat and an elastic fibrous 

 coat. The mucous coat is thin and smooth ; it is continuous, inter- 

 nally, with the mucous membrane of the bladder ; externally, with 

 the investing membrane of the glans ; and, in certain points of its 

 extent, with the lining membrane of the numerous ducts of mucous 

 glands, of those of Cowper's glands, the prostate gland, vasa 

 deferentia, and vesicular seminales. The elastic fibrous coat varies 

 in thickness in the different parts of the course of the urethra : it is 

 thick in the prostate gland, forms a firm investment for the mem- 

 branous portion of the canal, and is thin in the spongy portion, 

 where it serves as a bond of connexion between the mucous mem- 

 brane and the corpus spongiosum. The urethra is about nine inches 

 in length, and is divided into a prostatic, membranous, arid spongy 

 portion. 



The Prostatic portion, a little more than an inch in length, is 

 situated in the prostate gland, about one-third nearer to its upper 

 than to its lower surface, and extending from its base to its apex. 

 Upon its lower circumference or floor is a longitudinal fold of mucous 

 membrane the verumontanum, or caput gallinaginis, and on each 

 side of the veru, a depressed fossa the prostatic sinus in which 

 are seen the numerous openings of the prostatic ducts. At the an- 

 terior extremity of the verumontanum are the openings of the two 



* See my investigation upon this structure in the "Cyclopcedia of Anatomy and 

 Physiology." Article, " PENIS." . 



