|
|
|
|
OPENING THE ABDOMINAL CAVITY To open the abdominal cavity you only need to extend the incision you made for the thoracic cavity from where it was attached to the xiphoid process to the pelvic region. You may need to separate the abdominal wall (the oblique muscles) from the diaphragm. It will be necessary to make slots posteriorly so that the abdominal cavity lays completely open without the use of pins. The most obvious structure seen is the greater omentum which is a fatty sheet of serous tissue - do not remove the greater omentum. You will begin your dissection of the vessels of this region by lifting the viscera from the left side of the cat. Here you will easily identify the left kidney. Slightly anterior and medial to the kidney is some connective tissue which covers the descending aorta. Carefully tease away this tissue and find the descending (or abdominal) aorta. ABDOMINAL ARTERIES You will be following the descending aorta posteriorly in order to find the remaining arteries of this region. Procedure carefully and watch for important landmarks as you proceed. Many dissection points are lost at this point by students who forge ahead without knowing what they are looking for or where it might be. You will first find the celiac artery branching directly ventrally out of the descending aorta. The celiac itself branches into the left gastric and splenic arteries (actually the hepatic as well in most cats though this vessel is not required for either dissection or identification). These are identifiable as the gastric obviously connects to the stomach and the splenic to the spleen. Continuing down the descending aorta you will encounter the superior mesentaric artery which also branches ventrally from the descending aorta. The next branches off of the aorta are the paired adrenolumbar arteries. These are very thin delicate arteries that are best located by first identifying the adrenal gland. The adrenal gland lies separate and just slightly anterior to the kidney (not on top of the kidney as it is in humans. The adrenolumbar artery runs directly through this organ. Again following down the aorta you will next dissect the paired renal arteries which are quite large and of course infuse the kidney. Just posterior to where the renal arteries branched are the ovarian/spermatic arteries which connect to the gonads. Then you will encounter the inferior mesentaric artery which branches ventrally and is unpaired. The iliolumbar arteries branch laterally along the dorsal body wall. At this point the aorta sequentially 'forks' twice. The first 'fork' is the beginning of the external iliac arteries (which lead to the lower limbs). The second 'fork' results in three arteries, the two internal iliac arteries (which parallel the external iliacs) and the caudal artery which occurs between them. Find again the external iliac and follow it down the leg find the deep femoral artery. At this point the external iliac becomes the femoral artery. ABDOMINAL VEINS The inferior vena cava parallels the descending aortic artery. Find the adrenolumbar veins which drain the adrenal glands. The renal veins are very large and obvious. Genital veins are somewhat different for males and females. In the male the spermatic (testicular) is a branch off of the renal vein. In females the ovarian vein branches directly off of the inferior vena cava. Next find the iliolumbar vein which should be laying adjacent to the artery of the same name. Just posterior to the iliolumbar vein the inferior vena cava forms a trident. The middle of this trident is the caudal. To the lateral of the caudal branch the common iliac veins. The iliacs then become the external iliac and finally the femoral veins as they enter the leg. The venous system of the cat is notorious of its variability, stay awake! Finally find both the intestinal veins and arteries within the mesentary among the intestines.
| |||||||||||||||||||||||||||||||||||||||||||||||||||
|
Eric Genz-Mould
|
