360 



THE ANATOMY OF THE HORSE. 



Structure of the Urethra. The spongy pWion has been described 

 with the penis. The prostatic and membranous portions have a mucous 

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

 Observe the following points in connection with the interior of the 

 intra-pelvic part of the urethra (Fig. 50). On 

 the middle line of the roof of the tube, close 

 behind the communication with the bladder, 

 there is a mucous eminence — the colliculus 

 semincdis, or verumontanum. In the gelding this 

 is often small, and sometimes hardly recognis- 

 able, but in the stallion it is sometimes a con- 

 siderable 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 sufiiciently 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 uterus masculinus. 

 Insert a fine bristle into it, and guide 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 openings with a 

 linear arrangement. These are the orifices of 



Fig. 50. 



Bladder and Intrapelvic , ,, _ ,i.,i 



PORTION or Urethra the ducts 01 Cowper s glands. Insert bristles 



OPENED FROM BELOW . , p p 1 j_ i? • i ' J 



(Leyii). into a tew oi each set ot openings, and guide 



1. vaa deferens ; 1'. Bulbous them On iuto the respective glands. Close to 



part of tlie same ; 2. Dougla.ss'a iiii -ii. 



foid.joiningtheyasadeferentia; the necK of the bladder the epithelium of the 



3. Bladder; 4. Vesicula semi- ,, . p ,i i , . ,i 



naiis; 5. Orifices of ureters; Urethra 18 01 the Same character as m the 

 with^triflces' rf™^aTuutory bladder, but behind that point it is simple and 



ducts ; 8. Orifice of prostatic 

 vesicle ; 0. Cowper's gland ; 

 10. Orifices of ducts of pro- 

 state ; 11. Orifices of ducts of 



Cowper's gland; 12. Corpus -walls of these are composcd of iibrous, fibro- 



cavernosum ; 13. Corpus spongi- ^ "^ 



osum witiinrethra in its centre, musciilar, and viucovs layers; and contain many 

 tubular glands, which discharge their secretion 

 into the cavity, where 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 root 

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



>. Orifice of prostatic p„l,,™„5,r 



s). Cowper's gland; Columnar. 



Structure of the VBSicuLiE Sbminales. 



The 



