140 



PHYSIOLOGY 



CHAP. 



cavernosa of the penis, and forms a sheath to the urethral 

 canal. It commences as the bulb of the urethra which increases 

 in volume at puberty, reaches in the adult the size of a filbert, 

 and hypertrophies in old age. It continues along the free part 

 of the penis, in cylindrical form, and terminates in the corpus 



; i 



Fin. 32. Portion of a section of a corpus cavernosum of the penis injected from the deep artery of 

 the penis. (Henle.) Magnified 10 diameters. To left tunica albuginea ; * section of deep artery 

 of penis. 



spongiosum of the glans. Its structure differs in some particulars 

 from the corpora cavemosa of the penis (Fig. 33). The cavernous 

 spaces are very small ; the trabeculae which form them are thicker, 

 richer in connective tissue, and relatively poorer in muscular 



Fio. 33. Part of section of corpus spongiosum or corpus cavernosum of urethra injected from its 

 artery. (Henle.) Magnified 15 diameters. 1, tunica albuginea ; 2, urethral mucous membrane ; 

 3, section of a blood space in the mucosa ; 4, section of an artery. 



fibres. The blood spaces of the~corpus spongiosum do not com- 

 municate with those of the corpus cavernosum of the penis ; 

 the communications, however, between the corpus spongiosum 

 and that of the glans are numerous. The corpus spongiosum of 

 the glans forms a sort of mushroom head which receives in its 



