398 PRACTICAL ANATOMY. 



is trilateral or prismoidal in form and firm and erect in 

 position. Its upper surface is broad, and is called the 

 dorsum. The skin of the penis is very thin and loosely 

 attached to the underlying structures ; at the glans it be- 

 comes reduplicated, forming a cuff of skin, which covers 

 the glans, and is called the prepuce. The superficial 

 fascia rarely contains any fat- vesicles except at advanced 

 age. The glans penis is covered by mucous membrane, 

 which also lines the inner surface of the prepuce. The 

 extremity, or glans, is fashioned like a horse-chest- 

 nut, with its broad base attached to the body of the 

 penis. At the apex of the glans is the vertical meatus 

 urinarius. At the inferior part is the frsenum, a fold of 

 mucous membrane between the labia of the meatus and 

 the prepuce. The glans presents a rounded border, the 

 corona ; behind this is the cervix, which is provided with 

 numerous sebaceous follicles, the glands of Tyson, which 

 secrete sebaceous matter having a strong odor. 



The penis is formed of the two corpora cavernosa 

 above and side by side, and the corpus spongiosum be- 

 neath, in the groove between the corpora cavernosa. 

 The corpora cavernosa are two cylindrical structures, 

 which consist of an exterior fibrous coat, from the inte- 

 rior of which trabeculae pass off and form a fibrous 

 sponge-work or net-work, which contains the erectile 

 tissue in its meshes. The two corpora cavernosa are but 

 imperfectly separated by an incomplete septum, called 

 the pectiniform septum. Erectile tissue consists of a plexus 

 of anastomosing veins or venous sinuses, which, when 

 filled, entirely distend the meshes in the fibrous sponge- 

 work of the corpora cavernosa. During active erection the 

 blood in the sinuses is arterial and bright-red. In the 

 flaccid state of the organ the blood is dark in color. The 

 veins terminate principally in the dorsal vein, which 



