THE PKXIS. 1151 



integument is continuous with that upon the pubes and scrotum, and at the 

 neck of the glans it leaves the surface and becomes folded upon itself to form the 

 prepuce. 



The internal layer of the prepuce is attached behind to the cervix, and 

 approaches in character to a mucous membrane; from the cervix it is reflected 

 over the glans penis, and at the meatus urinarius is continuous with the mucous 

 lining of the urethra. 



The mucous membrane covering the glans penis contains no sebaceous glands. 

 but projecting from its free surface are a number of small, highly sensitive papillae. 

 Ar the back part of the meatus urinarius a fold of mucous membrane passes back- 

 Avard to the bottom of a depressed raphe, where it is continuous with the prepuce ; 

 this fold is termed the free nui pwputli. 



Structure of the Penis. The penis is composed of a mass of erectile tissue 

 enclosed in three cylindrical fibrous compartments. Of these, two, the corpora 

 , are placed side by side along the upper part of the organ ; the third, or 

 jinmun* encloses the urethra and is placed below. 



The Corpora Cavernosa form the chief part of the body of the penis. They 

 consist of tAvo fibrous cylindrical tubes, placed side by side, and intimately 

 connected along the median line for their anterior three-fourths, whilst at their 

 back part they separate from each other to form the crura, which are two strong 

 tapering fibrous processes firmly connected to the rami of the os pubis and 

 ischium. Each cms commences by a blunt -pointed process in front of the 

 tuberosity of the ischium, and before its junction Avith its felloAv to form the 

 bodv of the penis it presents a slight enlargement, named by Kobelt the bulb 

 <>f tin ni-fixx cio'i't'itoxion. Just beyond this point they become constricted, 

 and retain an equal diameter to their anterior extremity, Avhere they form a 

 single rounded end which is received into a fossa in the base of the glans penis. 

 A median groove on the upper surface lodges the dorsal vein of the penis, and the 

 groove on the under surface receives the corpus spongiosum. The root of the 

 penis is connected to the symphysis pubis by the suspensory ligament. 



Structure. The corpora cavernosa are surrounded by a strong fibrous em-elope, 

 consisting of two -sets of fibres the one, longitudinal in direction, being common 

 to the tAvo corpora cavernosa, and investing them in a common covering ; the 

 other, internal, being circular in direction, and being proper to each corpus 

 cavernosum. The internal circular fibres by their junction at one part form an 

 incomplete partition or septum between the tAvo bodies. 



The septum between the tAvo corpora cavernosa forms an imperfect partition ; 

 it is thick and complete behind, but in front it is incomplete, and consists of a 

 number of vertical bands, Avhich are arranged like the teeth of a comb, whence the 

 name which it has received, septum pectiniforme. These bands extend betAveen 

 the dorsal and the urethral surface of the corpora cavernosa. This fibrous invest- 

 ment is extremely dense, of considerable thickness, and consists of bundles of 

 shining white fibres, with an admixture of Avell-deA'eloped elastic fibres, so that it 

 is possessed of great elasticity. 



From the internal surface of the fibrous envelope, as Avell as from the sides of 

 the septum, are given off a number of bands or cords Avhich cross the interior of 

 the corpora cavernosa in all directions, subdividing them into a number of 

 separate compartments, and giving the entire structure a spongy appearance. 

 These bands and cords are called trabeeulce, and consist of Avhite fibrous tissue, 

 elastic fibres, and plain muscular fibres. In them are contained numerous 

 arteries and nerves. 



The component fibres of which the trabeculae are composed are larger and 

 stronger round the circumference than at the centre of the corpora cavernosa; 

 they are also thicker behind than in front. The interspaces, on the contrary, are 

 larger at the centre than at the circumference, their long diameter being directed 

 transversely : they are largest anteriorly. They are occupied by venous blood, 

 and are lined bv a laver of flattened cells similar to the endothelial lining of veins. 



