Carnivore Anatomy Lab 16 Introduction

CONTENTS:

Lab Objectives
Anatomical Terms
Instructor Commentary
Dissection Steps
Dissection Videos
Dissection Images

Lab Objectives:

• Open the abdominal cavity and identify peritoneal structures:
      - falciform ligament and the median ligament of the urinary bladder
      - vaginal ring (and its relationship to the inguinal canal & canal contents)
      - greater omentum (including the omental bursa & gastrosplenic ligament)

• Regions and openings of the diaphragm:
      - tendinous center
      - diaphragm muscle regions (right/left crus; costal & sternal)
      - openings (aortic hiatus; esophageal hiatus; caval foramen)

• Identify lobes of the liver, the gallbladder and associated ducts

• Examine alimentary tract viscera:
      - stomach (including its curvatures, regions, and sphincters)
      - duodenum (descending, ascending, and flexures)
      - jejunum and mesenteric lymph nodes
      - ileum and the ileal (ileocolic) orifice
      - cecum and the cecocolic orfice
      - colon (ascending, transverse, and descending)
      - rectum

• Also, find:
      - urinary bladder
      - duodenum (descending, ascending, and flexures)
      - spleen
      female:
      - uterus (cervix, body, & bilateral uterine horns)
      male:
      - ductus deferens (bilateral)

CONTENTS

Anatomical Terms:

Abdominal & Peritoneal Cavities
        transversalis fascia
        parietal & visceral peritoneum
        falciform ligament (fat filled)
                round ligament of the liver
        median ligament of the bladder
        vaginal ring
        deep inguinal ring
        ductus deferens
        caudal epigastric a. & v.

Abdominal Viscera
        greater omentum
                omental bursa
        urinary bladder [palpate]
        uterus [palpate] (cervix, body, uterine horns)
        spleen [palpate]
                gastrosplenic ligament
        diaphragm
                tendinous center
                lumbar part (left crus & right crus)
                costal part
                sternal part
                cupula
                aortic hiatus
                esophageal hiatus
                caval foramen
        liver
                right medial & lateral lobes
                quadrate lobe
                left medial & lateral lobes
                caudate lobe
                        caudate process (with renal impression)
                        papillary process
                hepatic ducts
        gallbladder
                cystic duct
        bile duct
        stomach
                cardiac part
                fundus
                body
                pyloric part
                        pyloric antrum
                        pyloric canal
                                pylorus (spincter)
                greater & lesser curvatures

        Small Intestines:
        duodenum
                cranial duodenal flexure
                descending part
                caudal duodenal flexure
                ascending part
                duodenojejunal flexure
        jejunum
        mesenteric lymph nodes (in mesojejunum & mesoileum)
        ileum
                ileal orifice (ileocolic orifice)

        Large Intestines:
        cecum
                cecocolic orifice (dog, indistinct in cat)
        colon (ascending, transverse & descending [palpate] )
                right & left colic flexures
        rectum

        Note:
             ileum [Latin] = distal end of the small intestines
             ilium [Latin] = the most cranial bone of the os coxae
             pylorus [Greek: pyloros] from pyle = gate and ouros = guard

CONTENTS

Instructor Commentary:

The mesojejunum and mesoileum (collectively known as the "mesentery") rotate 360 degrees around the axis of the cranial mesenteric artery during embryonic development. This rotation creates a narrow "root of the mesentery" (surrounding the cranial mesenteric artery).

The gross anatomical distinction between jejunum and ileum is remarkably different for human vs. veterinary anatomists. Human anatomists regard "jejunum" as the cranial 40% and "ileum" and the caudal 60% of the combined jejunum-ileum. Veterinary anatomists regard "ileum" as the short terminal segment of the small intestines, demarcated by the ileocecal fold and the presence of vessels on the intestinal anti-mesenteric surface. Although the jejunum and ileum exhibit differences histologically, there is not a distinct gross anatomical difference between them, beyond the anti-mesenteric vessels.

Lumbar musculature of the diaphragm, which attaches to bodies of lumbar vertebrae, is designated left crus and right crus, implying that the attachments are "legs" of the diaphragm. Two structures pass between the two crura: the aorta (through the aortic hiatus) and the esophagus (through the esophageal hiatus).

CONTENTS

Dissection Steps:

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Dissection Videos:

CONTENTS

Dissection Images:

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