---start anat.lec.12.2.96----

announcements for this week:

wed and thurs half the class will be going over to the med school for 
comparative anatomy.

we won't do the clinical correlation on thursday but rather will do it on 
Tuesday - it will be about the udder.

dr worson this friday am will talk to us about cranial nerves again. a 
summary, if you will. 

--

as you go through the pelvis, there is a lot of stuff to go over. much of 
it is similar to the dog. no heavy duty  blood vessel stuff. note the 
more clinical aspects of the pelvis - palpation is a big deal in large 
animals to evaluate GI and urogenital symptoms.

lots of people are confused about the palpation...realize,the rectum is 
pretty thin, so you can feel through it. be careful not to break it!

when you look at the uterus of these animals, note these differences 
between equine and bovine:

in the ruminants, the division between the horns continues after the two 
horns come together. eg, the cranial part of what looks like the body is 
still the horns, with a barrier between them. the horse isn't like that; 
the horse uterus has a larger body, with no area of horn in the vertical 
part of the uterus.

for this reason,the ruminant has the intercornual ligament between the 
horns at the cranial end of the uterus; the horse doesn't. this can be 
palpated in the ruminant.

also, if you look at the wall of the body of the equine uterus, it's 
smooth, with diffuse folds. the inside of the ruminant uterus has 
distinct caruncles, kind of look like tiny ovoid hives to me. this is 
indicative of the different placentation in these animals. the ruminant 
has a cotyledonary placenta.  the fetal membranes interdigitate with the 
caruncles, and the parts that cover the caruncles are called the 
cotyledon. put them together and you have a PLACENTOME. (eg, placentome = 
cotyledon plus caruncle) the horse has a diffuse placenta. there is very 
intimate contact between fetal membranes and uterine wall. 

blood supply to the uterus: similar to dog in the ruminant: you have an 
ovarian artery coming in to the ovary off the aorta and  uterine artery 
coming off the umbilical which comes off the internal iliac. there's also 
a uterine branch of the ovarian artery also which supplies the horn, 
whereas the uterine a supplies the body.

in the horse the ovarian also comes off the aorta, and the uterine branch 
goes to the horns. the uterine artery comes off the external iliac in the 
horse, not the internal iliac. this is specific to the horse.

male urogenital tract:
review the lecture about penises that we had last quarter.

think about this. testis develops retroperitoneally, near the kidney, but 
needs to end up in the scrotum. it descends retroperitoneally, internal 
to the abdominal musculature. then it needs to get THROUGH the muscle 
into the scrotum. so there has to be a hole or tunnel through the muscle. 
we'll call it a canal. this canal is referred to as the INGUINAL canal, 
and the testis travels through it, pulling down its associated vessels 
ducts and nerves. 

the deep opening of this canal is the DEEP INGUINAL RING and the 
superficial opening is the SUPERFICIAL INGUINAL RING. 

so, you may ask, what the hell is the VAGINAL RING? 
well, the parietal peritoneum has an outpouching into the scrotal region. 
as the peritoneum goes through the inguinal canal and balloons out into 
the scrotum, there is an opening deep to the deep inguinal ring, and 
that's the vaginal ring. all of the "peritoneum" outside of this ring (eg 
in the inguinal canal and in the scrotum) is called the VAGINAL TUNIC.

as the testis descends, it is STILL "retroperitoneal" or outside of the 
vaginal tunic. but as it grows, it causes the vaginal tunic to 
invaginate/wrap around the testis, so it has a visceral and parietal 
layer - caused by the "fist in the balloon" syndrome we've seen before...


a cross section through the proximal vaginal tunic shows what looks kinda 
like mickey mouse ears. in one ear is the artery veina nd nerve, in the 
other ear is the ductus deferens.

if you look into the pelvis from the dorsal aspect (in the male)

-EQUINE

ampulla: dilation of ductus deferens in the caudal/distal area. it has a 
thick glandular wall

vesicular glands: not obvious in horse; formerly called seminal vesicles 
- look more bladder like, vesicular.

prostate: bilobed

bulbourethral glands: bilobed, not that prominent in immature anim
-RUMINANT
 
ampulla similar to horse

vesicular glands are truly glandular

prostate: kind of disseminated structure. isn't actually lobed, more 
contained w/in wall of urethra. in the small ruminants, the prostate is 
actually within the wall of the urethra. in the bull, both the bilobed 
and disseminate forms of the prostate are present (don't need to know 
that for this course.)

bulbourethral glands: bilobed
---end----