_1_, Bulbo-urethral (Cowper’s) gland; _2_, transversus perinei muscle
(?); _3_, ischio-urethral muscle; _4_, retractor penis muscle; _5_,
bulbo-cavernosus muscle. (After Schmaltz, Atlas d. Anat. d.
Pferdes.)
]
1. The last pair of =lumbar arteries= pass up through the foramina at
the junction of the last lumbar vertebra and the sacrum.
2. The =internal pudic artery= (A. pudenda interna) arises near the
origin of the internal iliac. It passes backward and somewhat downward,
at first along the iliac head of the obturator internus, then above the
superior ischiatic spine on the inner surface of the sacro-sciatic
ligament, perforates the latter and runs for a variable distance in its
substance or on its external face. It then re-enters the pelvic cavity,
passes backward on the retractor ani to the ischial arch, and divides
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 fœtus, 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 fœtal 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.[167] It gives off small =vesical branches= (Aa. vesicates
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.
[Illustration: