918 



PENIS. 



at their extremities. The first of these ap- 

 pearances is due to the accidental position of 

 the section under the microscope, so that the 

 short trunk with its terminal twigs appears to 

 be placed within the area of a vein projecting 

 into it like a blossom on its stalk ; the second 

 results from the contraction of the coats of the 

 artery, the effects of the longitudinal contrac- 

 tion giving rise to the curve and to the enlarge- 

 ment near its extremity, and the transverse 

 contraction, by producing the expulsion of 

 some part of the injection, to the conical form 

 of the extremity itself. " These remarkable 

 arteries," writes Miiller,* " have a great re- 

 semblance to the tendrils of the vine, only that 

 the arteries are much shorter in proportion to 

 their thickness; from this resemblance I have 

 named them arterise helicinse or tendril-like 

 arteries. We may also compare their ends to 

 the top of a crook. By close examination 

 with the microscope they may be seen pro- 

 jecting into the venous cells, not, however, bare, 

 but covered with a fine membrane that under 

 the object-glass looks horny." 



If the description which I have here given 

 of erectile tissue be the true one, it is clear 

 that the arteriae helicinse have no existence, and 

 that that appearance of the small vessels, to 

 which Mu'ller has given this name, is a neces- 

 sary consequence of the natural distribution of 

 the ordinary vessels of the organ. I may be 

 permitted to remind my junior reader that it 

 was through the medium of the arterise heli- 

 cinse that Mu'ller supposed the venous canals 

 of erectile tissue to be filled during erection, 

 while, for the purposes of nutrition and main- 

 taining the ordinary circulation of the organ, 

 the arteries pour their blood into capillaries, 

 and these into veins. Excepting during the 

 moment of discharging their blood, this phy- 

 siologist conceived that the small curved ter- 

 minal twigs were impermeable, and that it was 

 only under the influence of the erectile nervous 

 function attending erection that the impetus 

 of the arterial blood was sufficient to open the 

 concealed apertures at their extremities. 



The lymphatic vessels of the penis are found 

 chiefly on its dorsum, taking the course of the 

 dorsal vein. At the root of the organ they 

 curve outwards to the groin, and communicate 

 with the upper group of inguinal glands. I 

 have frequently seen a small lymphatic gland 

 on the dorsum penis near its root. 



The nerves of the penis are derived from the 

 internal pudicand from the hypogastric plexus; 

 those from the former source are the anterior 

 superficial perineal nerve, the nerve of the bulb, 

 and the dorsalis penis nerve. 



The anterior superficial perineal is a branch 

 of the perineal division of the internal pudic. 

 It enters the perineum at the posterior border 

 of the deep perineal fascia, and passing on- 

 wards in the groove between the erector penis 

 and accelerator urinse, gives branches to the 

 scrotum, and is finally distributed to the inte- 

 gument of the under part of the penis as far as 

 the prepuce. 



* Archiv, 1835. 



The nerve of the bulb is also a branch of the 

 perineal division of the internal pudic, and 

 likewise enters the perineum through the 

 posterior border of the deep perineal fascia. 

 Between the superficial and deep fascia, and 

 behind the transversus perinei muscle, the 

 nerve passes obliquely forwards to the bulb, 

 where it gives off several long and slender 

 branches, which run forwards on the fibrous 

 tunic of the corpus spongiosum, and then 

 enters the bulb in company with the artery, 

 to be distributed to the vascular parenchyma 

 of that body and to the urethra as far as the 

 glans penis. 



The perineal division of the internal pudic 

 nerve also gives branches to the acceleratores, 

 erectores, and ischio-bulbosi muscles. 



The dorsal nerve of the penis is the superior 

 or deep division of the internal pudic. This 

 nerve accompanies the internal pudic artery to 

 the anterior part of the arch of the pubis, 

 where it pierces the deep perineal fascia and 

 passes onwards to the dorsum penis. In the 

 latter situation it lies externally and somewhat 

 superficially to the dorsal artery, and enters the 

 base of the glans penis by several branches, to 

 be distributed to the papillae of that body. 

 Near the root of the penis the dorsal nerve 

 gives off a large branch, which passes obliquely 

 along the side of the corpus cavernosum, and 

 divides into numerous long and slender branches, 

 which are distributed to the integument of the 

 upper and lateral aspect of the penis, to the 

 fibrous covering and substance of the corpus 

 cavernosum, and to the prepuce. The nervi 

 dorsales communicate with each other, on the 

 dorsum penis, by anastomosing filaments. 



The nerves derived from the hypogastric 

 plexus are slender ramuscules, which accom- 

 pany the arteries of the corpus cavernosum and 

 bulb into the interior of the penis, and are dis- 

 tributed to its internal structure. 



Developement. The first indication of the 

 developement of a penis is perceived towards 

 the end of the fifth week after conception, at 

 which time it exists in the form of a slight 

 prominence, situated immediately in front of 

 the common urino-sexual aperture. By the 

 seventh or eighth week this prominence assumes 

 the lengthened character of the future organ, 

 and is grooved along its under side, the groove 

 being an extension of the common urino-sexual 

 cleft. The glans penis makes its appearance 

 during the ninth week, and the urinary groove 

 is continued beneath it. During the tenth and 

 eleventh weeks the urinary groove becomes 

 separated from the anus by the growth of a 

 transverse septum, and the borders of the groove 

 begin to lengthen and coalesce on the median 

 line, in order to form the urethra. This process 

 commences from behind, and proceeds for- 

 wards towards the glans, attaining its comple- 

 tion at about the fifteenth or sixteenth week. 

 When it remains imperfect from arrest of deve- 

 lopement, it constitutes that form of deficiency 

 which is termed Hypospadias. The prepuce 

 is developed at the same time with the closure 

 of the urethra. 



(Erasmus Wilson.) 



