Part of the right wall of the uterus and vagina is removed and the
cervix uteri is shown in sagittal section. _a_, Aorta; _b_,
utero-ovarian artery; _b′_, ovarian, and _b″_, uterine branch of
_b_; _c_, external iliac artery; _d_, right internal iliac artery;
_e_, common trunk of umbilical artery (_e′_) and middle uterine
artery (_f_); _g_, ilio-lumbar artery; _h_, anterior gluteal
arteries; _i_, middle hæmorrhoidal artery; _k_, posterior uterine
artery; _l_, perineal artery; _m_, posterior gluteal artery; _n_,
obturator arteries; _o_, artery of clitoris; _p_, posterior
mesenteric artery; _r_, anterior hæmorrhoidal artery; _s_, middle
sacral artery; _1_, ovary; _2_, apparent body of uterus, really
apposed horns; _2′_, cornu; _3_, vagina; _4_, cervix uteri; _4′_,
vaginal part of uterus (os uteri); _5_, _5′_, broad ligaments, large
part of right one removed; _6_, urinary bladder; _7_, rectum; _8_,
sacrum; _9_, symphysis pelvis. (After Zieger.)
]
The =middle sacral artery= is a vessel about 5 mm. in diameter which
continues the aorta. It arises from the dorsal face of the aorta at the
angle of divergence of the internal iliacs, runs backward on the pelvic
surface of the sacrum a little to the left of the median line, and is
continued as the middle coccygeal artery. It gives off small collateral
branches to the spinal cord and the muscles of the tail and the =lateral
coccygeal arteries=. The latter may have a common trunk of origin, and
each divides into dorsal and ventral branches. The =middle coccygeal
artery= runs through the ventral (hæmal) arches of the coccygeal
vertebræ. The coccygeal arteries are connected at pretty regular
intervals by segmental anastomoses.
The =internal iliac arteries= are much longer than in the horse. Each
passes backward on the sacro-sciatic ligament and divides about the
middle of the pelvic wall into posterior gluteal and internal pudic
branches. The chief differences in its distribution are: (1) A large
trunk gives origin to the umbilical and middle uterine arteries. The
=umbilical artery= is usually largely obliterated and its terminal
branches receive their blood through anastomoses with the internal
pudic. It gives off near its origin two small vessels, the ureteral
artery (A. ureterica) and the deferential artery (A. deferentialis),
which accompany the ureter and the vas deferens respectively. The
=middle uterine artery= (A. uterina media) is very large. It is
distributed chiefly to the cornu of the uterus, and compensates for the
small size of the utero-ovarian artery. (2) The =ilio-lumbar= artery is
relatively small and is distributed chiefly to the sublumbar muscles. It
is sometimes replaced by branches of the circumflex iliac and gluteal
arteries. (3) The =anterior gluteal artery= is commonly represented by
several vessels. (4) The =obturator artery= is represented by several
small branches which supply the obturator and adductor muscles. (5) The
=iliaco-femoral= and =lateral sacral arteries= are absent. The absence
of the latter is compensated by the middle sacral and gluteal arteries.
(6) The =posterior gluteal= (or ischiatic) artery is large. It emerges
through the lesser sciatic notch and ramifies in the biceps femoris and
adjacent muscles. (7) The =internal pudic artery= (A. urethro-genitalis)
is the direct continuation of the internal iliac. It gives off branches
to the rectum, bladder, urethra, and genital organs. In the male it
supplies the accessory genital glands and divides into dorsal and deep
arteries of the penis; the a. dorsalis penis runs along the dorsum penis
to the glans and gives twigs to the prepuce; the a. profunda penis gives
off a perineal branch and enters the corpus cavernosum penis. In the
female it gives off a large posterior uterine artery, which supplies the
posterior part of the uterus and gives branches to the vagina and
bladder. It ends as the a. clitoridis, which supplies the clitoris and
adjacent parts.