188 EQUINE ANATOMY. 



uated in the pelvic cavity, above the bladder and the 

 vas deferens, it has a middle portion covered by the 

 rectum ; an anterior extremity, the largest forming a 

 cul de sac ; a posterior extremity tapering to a narrow 

 neck and receiving at an acute angle the termination 

 of the vas deferens. Structure : an internal mucous 

 coat, a middle muscular and an external fibrous. 



The ejaculatory ducts, formed by the union of the 

 vesiculse seminalis and the vas deferens, terminate in 

 the urethra on the side of the veru montanum. 



Urethra. — A membranous canal extending from the 

 neck of the bladder to the end of the penis. Course: 

 from its origin backwards in the pelvic cavity, there 

 bonds downwards over the ischial arch between the 

 two roots of the corpus cavernosum, forward to the 

 head (glans) of the penis, terminating by the urethral 

 tube. It is divided into an intra pelvic or membran- 

 ous, and an extra pelvic or spongious portion. 



Interior. — Constricted at its origin, it expands at the 

 prostate gland, forming the cul de sac of the bulb or 

 ventricle ; tlien contracts over the ischial arch, and 

 remains of the same size to the end. Behind the ure 

 thral tube is the fossa navicularis. On the mucous 

 membrane it presents the openings of the prostrate 

 gland, the urethral ridge or veru montanum and the 

 excretory canals of Cowper's glands. Structure : a 



