348 



THE ANATOMY OF THE HORSE. 



with the penis. The prostatic and luembranous portions have a 

 miicmts lining, external to which is a imiscuhxr coat of non-striped fibres. 

 Observe the following points in connection with the interior of the 

 intra-pelvic part of the urethra (Fig. 44). On 

 the middle line of the roof of the tube, close 

 behind the communication with the bladder, there 

 is a mucous eminence — the colliadus seminalis, or 

 verumontanum. In the gelding this is often small, 

 and sometimes hardly recognisable, but in the 

 stallion it is sometimes a considerable eminence, 

 like the tip of the little finger. At each side of 

 this projection is the orifice of the ejaculatory 

 duct. These orifices in the stallion are sufficiently 

 large to permit of the tip of the little finger 

 being insinuated into them. This should be 

 remembered, as the point of catheter, if not 

 guided along the floor of the urethra, might 

 easily pass into one of them. At the summit of 

 the colliculus, and therefore on the middle line, is 

 a very minute opening — the orifice of the utenxs 

 masculinus. Insert a fine bristle into it, and 

 giiide it on into the tube. On the wall of the 

 urethra at each side of the colliculus, observe an 

 irregular series of minute orifices which belong to 

 the ducts of the prostate gland. Behind these 

 on each side, notice another series of small open- 

 ings with a linear arrangement. These are the 

 orifices of the ducts of Cowper's glands. Insert 

 bristles into a few of each set of openings, and 

 guide them on into the respective glands. Close 

 to the neck of the bladder the epithelium of the 

 urethra is of the same character as in the bladder, 

 but behind that point it is simple and columnar. 



Structure of the Vesicul^e Seminales. The 

 walls of these are composed of fibrous, fibro- 

 muscular, and mucous layei-s ; and contain many 

 tubular glands, which discharge their secretion 

 into the cavity, Avhere it mixes with the semen. 

 The bulbous portion of each vas deferens has the 

 same structure. 



Directions. — The student must now return to the pelvis, at the roof of 

 which he is to dissect the lumbo-sacral plexus of nerves, and the 

 branches of the internal iliac artery (Plate 48). Thereafter he is to 

 examine the pyrifoiinis and obturator internus muscles. 



Fig. 44. 



Bladder and intrapelvic 

 PORTION OF Urethra 



OPENLD FROM BELOW 



{Uyh). 

 1. Viis deferens; 1'. Bulb- 

 ous part of the s<ame ; 2. Peri- 

 toneal fold joining the vasa 

 deferentia ; 3. Bliidder ; 4. 

 Vesicula Beminalis ; 5. Ori- 

 fices of ureters ; 6. Prostate ; 

 7. Verumontanum with ori- 

 fices of ejaculatory ducts ; 8. 

 Orifice of prostatic vesicle ; 

 9. Cowper's gland ; 10. Ori- 

 fices of ducts of prostate ; 11. 

 Orifices of ducts of Cowper's 

 gland; 12. Coipus caver- 

 nosum ; 13. Corpus spongi- 

 osum with urethra in its 

 centre. 



