DISSECTION OF THE PERINEUM IN THE MALE. 291 



without stretching when the organ becomes erect. 2. The posterior 

 dorsal artery of the penis is a branch of the cavernous artery (from the 

 obturator). It runs forwards on the dorsal aspect of the fixed portion 

 of the penis, and anastomoses with the posterior division of the anterior 

 dorsal artery. These arteries are mainly expended in branches to the 

 cavernous and spongy portions of the penis, and they also give off some 

 twigs to the prepuce. 



Dorsal Nerves of the penis. These nerves, right and left, accom- 

 pany the dorsal vessels on the dorsum, or upper surface of the penis. 

 Each is the continuation of the pudic nerve, which reaches the penis by 

 turning round the ischial arch. In proceeding forwards along the 

 penis, the nerves are disposed in a flexuous manner to allow them to be 

 adapted without stretching to the varying length of the organ. They 

 emit numerous branches to the cavernous and spongy portions of the 

 penis, and terminate in the glans. 



Suspensory Ligaments of the penis (Plate 46). These are two 

 fibrous bands, right and left, which are attached superiorly to the 

 tendon of origin of the gracilis, and below to the cavernous body of 

 the penis. 



Directions. — The penis may now be freed as far as its posterior 

 extremity, and its surface cleaned of vessels, nerves, and connective- 

 tissue. On one side the erector penis muscle should be removed, to lay 

 bare the crus and expose the artery of the corpus cavernosum. 



The Artery of the Corpus Cavernosum (Plate 46). This is a branch 

 of the obturator artery, detached after the emergence of that artery 

 from the obturator foramen. It passes backwards on the lower face of 

 the ischium, and perforates the crus penis. It gives off as a collateral 

 branch the posterior dorsal artery of the penis. 



The Penis (Plates 46 and 47, and Fig. 40) is the male organ of copula- 

 tion. It begins at the ischial arch, where it is attached by its crura to the 

 ischial tuberosities ; and it terminates anteriorly in a free enlargement 

 — the glans. It may be said to consist of a posterior fixed portion, and 

 an anterior portion which is free and protrusible. The former portion 

 extends from the ischial arch to the scrotum ; the latter, when the 

 organ is non-erect, is lodged in the prepuce, but during erection the 

 prepuce becomes obliterated, and this part of the penis then projects 

 freely in front of the scrotum. 



The penis is compounded of three longitudinal and parallel columns, 

 viz., two corpora cavernosa and a single corpus spongiosum. From the 

 relationship of these to one another, the penis has been happily 

 compared to a double-barrelled gun, the barrels being represented 

 by the corpora cavernosa, and the ramrod by the corpus spongiosum. 



The Corpora Cavernosa. Each corpus cavernosum begins at the 

 tuber ischii, to whose inferior ridge (inferior ischiatic spine) it is firmly 



