574 



BLOOD-VASCULAR SYSTEM OF THE HORSE 



into the perineal and the artery of the bulb in the male, perineal and artery of the 

 clitoris in the female. It is accompanied by the internal pudic nerve. Its chief 

 branches are as follows: 



(1) The umbilical artery is given off from the internal pudic about an inch 

 (ca. 2 to 3 cm.) from the origin of that vessel. It is a very large artery in the 

 foetus, in which it curves downward and forward at the side of the bladder in the 

 edge of the umbilical fold of peritoneum, passes through the umbilical opening, 

 becomes a component of the umbilical cord and ramifies in the foetal placenta. 

 After birth it extends only to the vertex of the bladder and is much reduced. Its 

 lumen is almost obliterated and its wall is very thick, giving the vessel a cord-like 

 character, hence it is commonly termed the round ligament of the bladder.^ It 



Coccygeus muscle 

 Anal lymph glands 

 Branch of posterior gluteal 

 arttry 



Posterior hcemorrhoidal 

 nerve 



Vulvar branch of 

 pudic nerve 

 Internal pudic 

 artery 



Branch of pu- 

 dic nerve to 

 clitoris 



Obturator artery 



Fig. 453. — Dissection of Perineum or Mare. 

 1, Sacro-coccygeus .superior; 2, sacro-coocygeus lateralis; 3, intertransversales; 4, sacro-coccygeus inferior; 

 6, recto-coccygeus; 6, sphincter ani externus; 6', branch connecting sphincter ani with constrictor vulvae; /• 

 vestibular bulb; 8, tuber ischii; 9, sacro-sciatic ligament. (After Schmaltz, Atlas d. Anat. d. Pferdes.) 





gives oE small vesical branches (Aa. vesicales craniales) to the bladder, and twigs 

 to the prostate and vasa deferens in the male. In the mare a small branch runs 

 forward along the ureter into the broad ligament of the uterus. 



(2) The middle haemorrhoidal (jr vesico-prostatic artery (A. hsmorrhoidalis 

 media) in the male arises usually near the prostate and runs backward lateral to 

 the rectum. It supplies l^ranches to the rectum, bladder, urethra, and accessory 

 genital glands. In the female the homologous vessel is much larger and gives off 

 the posterior uterine artery (A. uterina caudalis). This runs forward on the side 

 of the vagina, to which it gives branches, and ramifies on the liody of the uterus, 

 anastomosing with the anterior and middle uterine arteries. (In some cases this 

 artery arises from the internal iliac or the umbilical.) 



(3) The perineal artery (A. perinei) is relatively small in the male. It passes 



'^ The obliteration in the adult extends a variable distance from the vesical end toward the 

 origin, but usually involves only a small part. 



