THORAX AND ABDOMEN OF THE HORSE 77 



the penis towards the glans as the dorsal artery of the 'penis (a. dorsalis 

 penis), deep rami (rami profundi penis) of which pierce the 

 albugineous tunic of the penis. The caudal branch of the external 

 pudental artery supplies the scrotum and penis and very often 

 anastomoses with a branch of the obturator artery. 



. V. PUDENDA EXTERNA. — The region of the prepuce and penis 

 contains a large number of veins between which are frequent anastomoses. 

 These, by their union, produce the cranial and caudal radicles of the 

 external pudendal vein, which is a companion of the artery of the same 

 name. Not infrequently the saphenous vein of the thigh joins the 

 external pudendal. 



The nerves of the prepuce are derived from the ilio-hypogastric, 

 ilio-inguinal and genito-femoral (external spermatic). 



Dissection. — Remove the prepuce entirely and clean the surface of 

 the penis, being careful, however, to leave the dorsal vessels and nerves 

 in position. To obtain a complete view of the penis, it is necessary to 

 dissect its connection with the sciatic arch. Here care must be 

 exercised not to injure the termination of the internal pudendal vessels. 



The penis. — The penis consists of a middle part or body (corpus 

 penis), a root (radix penis), attached to the sciatic arch, and a free 

 extremity or glans^ (glans penis) that lies in the region of the 

 umbilicus enclosed within the prepuce. Close to the root, two pale, 

 strong bands, the suspensory ligaments (ligamenta suspensoria), connect 

 the outer coat of the penis to the symphysis of the two ischial bones 

 and the origin of the gracilis muscles. 



Except near its extremities, the penis is compressed laterally and 

 therefore possesses right and left surfaces and two rounded borders. 

 The term dorsum penis is applied to that border of the organ that is in 

 contact with the abdominal wall and the corresponding part of the 

 pelvis ; whereas the opposite border is called the urethral surface 

 (facies urethralis) from the circumstance that the urethra here occupies 

 a groove formed by the cavernous body of the penis. 



Tlie body of the penis lies in the middle line, dorsal to the testes, 

 and is crossed laterally by the deferent ducts and the other components 

 of the spermatic cord. It is composed of three erectile cavernous bodies 

 running parallel to each other. 



The corpus cavernosuvi penis is generally described as consisting of 



two rods of erectile tissue bound together by a dense, thick, fibrous 



envelope, the tunica alhuginea [corporum cavernosuTn], and separated 



from each other by a fibrous septum (septum penis). In the ischial 



1 Gla7is [L.], an acorn. In a borrowed sense, an acorn -shaped ball of lead or clay 

 that was slung at an enemy, a Ijullet. 



