CONTENTS:

 

Lab Objectives:

• Identify branches of the abdominal aorta:
      - paired arteries to the abdominal wall (lumbar arteries & deep circumflex iliac a.)
      - paired arteries to viscera (renal a. & ovarian/testicular a.)
      - unpaired arteries to viscera (celiac a., cranial mesenteric a., & caudal mesenteric a.)

• Examine the portal vein and its branches.

• Open the pelvic canal (by cutting through the pelvic symphysis) and find:
      - the pelvic diaphragm (levator ani and coccygeus muscles)
      - pelvic n. and pelvic plexus (including hypogastric n. input to the plexus)
      - compartments of the peritoneal cavity

 

Anatomical Terms:

Branches of the Abdominal Aorta
        lumbar arteries
        celiac a.
                hepatic a.
                        cystic a.
                        right gastric a.
                        gastroduodenal a.
                                right gastroepiploic a.
                                cranial pancreaticoduodenal a.
                left gastric a.
                        esophageal branches
                splenic a.
                        left gastroepiploic a. (aa.)
                        pancreatic branches
        cranial mesenteric artery
                common trunk (in the dog)
                        middle colic a.
                        right colic a.
                        ileocolic a.
                                mesenteric ileal branch
                                colic branch
                                cecal a.
                                        antimesenteric ileal branch
                caudal pancreaticoduodenal a.
                jejunal aa.
                ileal aa.
        common trunk (phrenicoabdominal a.)
                cranial abdominal a.
                caudal phrenic a.
        renal a.
        ovarian a. / testicular a. (in mesorchium)
        caudal mesenteric a.
                left colic a.
                cranial rectal a.
        deep circumflex iliac a.

Portal Vein
        gastroduodenal vein
        splenic vein
                left gastric vein
        cranial & caudal mesenteric veins

Pelvic Viscera, Vessels, & Nerves
        pelvic diaphragm:
                levator ani m.
                coccygeus m.
        pelvic nerve & pelvic plexus

Extensions (excavations) of peritoneal cavity:
        pararectal fossa
        rectogenital pouch
        vesicogenital pouch
        pubovesical pouch

 

Instructor Commentary:

In general, body regions are supplied by arterial loops fed by more than one major artery. This arrangement is particularly obvious in the case of abdominal viscera because vessels can be viewed in mesenteries. Notice that branches of the celiac and cranial and caudal mesenteric arteries are connected through distal loops. Also, the abdominal aorta participates in top-level loops connecting the parent arteries.

The presence of vascular loops allows surgeons to ligate individual vessels with the expectation that blood will find its way to a particular region by alternate branches. However, the brain and the heart represent two regions where arterial looping is not robust. As a result, blockage of an artery in these regions often results in tissue death, leading to heart attacks and strokes.

All of the paired arteries that originate from the abdominal aorta have satellite veins that drain directly or indirectly into the caudal vena cava. However, blood conveyed by the three unpaired arteries supplying digestive organs and spleen must drain into the portal vein. The portal vein empties into liver sinusoids, from which blood reaches the caudal vena cava via hepatic veins.

As you prepare to identify the individual abdominal arteries that supply digestive organs and the spleen, keep the following overview in mind:

        • The celiac a. supplies cranial viscera (spleen, liver, pancreas, esophagus, stomach, and descending duodenum). The caudal mesenteric a. supplies the descending colon and rectum. The cranial mesenteric a. supplies everything in between (ascending duodenum, jejunum, ileum, cecum, ascending and transverse colon).

        • The celiac a. sends two branches to the left side (splenic and left gastric) and one to the right side (hepatic). The stomach receives a quadrant blood supply: left/right gastric arteries (lesser curvature) and left/right gastroepiploic arteries (greater curvature).

        • The cranial mesenteric a. sends:
- a branch to the ascending duodenum (caudal pancreaticoduodenal a.),
- a common trunk (in the dog) to the large intestines:
        ileocolic a. to the ileum (antimesenteric ileal a.), cecum, and adjacent colon;
        right colic a. to ascending colon;
        middle colic a. to transverse colon
- numerous jejunal arteries before terminating in a mesenteric ileal artery

 

Dissection Images:

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