1248 



URETHRA. 



effect of this muscular apparatus must be to 

 support and compress this part of the urethra, 

 and to prevent any retrogression of the 

 seminal fluid in the venereal act. 



The urethra now enters the corpus spoiigi- 

 osum, by which it is surrounded, until its ter- 

 mination at the extremity of the glans penis. 

 The spongy body surrounds the urethra 

 equally, except at the bulb and at the glands : 

 in the former situation there is a much thicker 

 layer below than above, which gives to the 

 bulb an appearance of great dilatation, whilst 

 at the glans there is but very little of this 

 structure at the under part. The bulb and 

 the glans, both dilatations of the spongy body, 

 bear a tolerably constant relation to each 

 other. 



This part of the canal is called the spongy 

 portion : it has already been stated that its 

 length varies in different subjects, and accord- 

 ing to the condition of the penis, being 4 or 5 

 inches in the flaccid state, and 6 or 8 inches in 

 the erect condition of the organ. It com- 

 mences at the termination of the membranous 

 portion, and is lodged in a groove between 

 and beneath the corpora cavernosa penis, 

 forming, with its investing corpus spongiosum, 

 a convexity, projecting beyond the general 

 circumference of the penis. 



The direction of the spongy portion is 

 curved ; it passes upwards in front of the 

 lower part of the symphysis pubis as high as 

 the suspended part of the penis ; and then 

 taking the direction of this organ, it bends 

 downwards, thus forming an abrupt curve : 

 by simple traction of the penis forwards and 

 upwards, it can be rendered perfectly straight. 



If the spongy part of the canal be laid 

 open longitudinally, it is found to be plicated, 

 the folds running from behind forwards, and 

 dovetailing with one another when the urethra 

 is closed. This plicated arrangement of the 

 mucous membrane of the spongy portion 

 was observed by Bichat and others, and is 

 due to the contraction of the submucous tis- 

 sue : if the urethra be immersed in alcohol 

 and examined with the aid of a simple lens, 

 an arborescent arrangement of the folds is 

 visible at the anterior part of the canal, in 

 appearance not unlike the plicae in the mu- 

 cous membrane of the cervix uteri. 



The spongy portion varies in diameter in 

 different parts ; thus, dilated at its commence- 

 ment in the bulb, it gradually tapers until it 

 reaches the glans, when it suddenly expands 

 into the fossa navicularis, to be again con- 

 tracted at the meatus. 



The bulb (pars bulbosa urethra; et pars sub- 

 pitbica) is the widest part of the spongy por- 

 tion. Lisfranc found in twelve subjects it 

 varied in diameter from 5 to 7 lines. Home 

 and most anatomists who have examined the 

 urethra, have come to the general conclu- 

 sion that the bulbous portion presents a de- 

 cided dilatation, and a simple examination of 

 the part would lead to a similar conclusion. 

 I cannot, therefore, conceive why there should 

 be any doubt on the subject. Injections of 

 wax prove to my mind an undoubted dilata- 



tion of the bulbous part ; Krause and Guthrie, 

 however, deny that any such exists. 



Kobelt has shown, that if the bulb be in- 

 jected, the corpus spongiosum at this part 

 presents two lateral hemispherical swellings, 

 separated from each other in the middle line 

 by a longitudinal depression. " This is caused 

 by a septum which divides the posterior part 

 of the bulb into two lateral symmetrical halves; 

 but anteriorly it is gradually lost. The two 

 portions of which it indicates that the bulb 

 is composed, are the analogues of the com- 

 pletely divided portions of the bulb and corpus 

 spongiosum in the whole of the marsupial 

 tribe."* " In the middle of the bulb there is 

 a slight superficial elevation (colliculits bulbi 

 medium), which is situated above and between 

 them, but does not extend so far backwards 

 as they do, and gives passage to the mem- 

 branous part of the urethra, the vessels and 

 nerves of the bulb, and the ducts of Cowper's 

 glands." f 



The extremity of the caput gallinaginis 

 sometimes reaches the bulbous portion, and 

 the ducts of Cowper's glands terminate in its 

 floor by two minute orifices, extremely dif- 

 ficult to find. This part of the canal extends 

 for about the fourth part of an inch or less, 

 the anterior layer of the deep perinaeal fascia 

 covers it underneath, and it is completely in- 

 vested by the accelerators urina?. 



The remainder of the spongy portion is 

 united to the bulbous at an angle of 45 in the 

 flaccid state of the penis ; but when this organ 

 is erect, this part of the canal is rendered 

 perfectly straight : it terminates at the meatus 

 urinarius. 



The extremity of the spongy portion is called 

 the glandular part (pars glandularis), being 

 surrounded by the glans penis. When the 

 urethra has entered the glands, it dilates into 

 a fossa from 4 to 6 lines in length, this is 

 termed the fossa navicularis Morgagnii, When 

 cut transversely, it has the appearance of a 

 longitudinal fissure. The urethra is sur- 

 rounded unequally by the glans penis ; the 

 floor of the navicular fossa is covered by a 

 very thin layer of this extension of the spongy 

 body, whilst its sides and upper surface have 

 a considerable investment from the glans. 



The urethra having traversed the corpus 

 spongiosum and the glands, terminates at the 

 anterior and inferior part of this body, by a 

 small slit-like orifice of two or three lines, the 

 long axis of which is vertical : from this a 

 small fold of membrane passes down to join 

 the prepuce, and is termed thefrtenum prce- 

 putii. The effect of this latter is, when the 

 penis is erect, to draw down the opening of 

 the urethra, and thus to narrow the orifice, 

 and direct the contents of the urethra clown- 

 wards and forwards. The two sides of the 

 meatus urinarius are kept in apposition by 

 the projection of the glans, and they are 

 joined below by a delicate fold of mucous 



* British and Foreign Quarterly Review, vol. xix. 

 p. 508. 

 t Ibid. 



