THE VASCULAR SYSTEM (Continued)
VEINS POSTERIOR TO THE HEART[1]
Blood from the parts of the rat posterior to the heart enters the right auricle through the inferior vena cava (post cava). Trace the vena cava caudally to the diaphragm, which it pierces, then enters the abdominal cavity. In the thoracic cavity the vein is surrounded by the lobes of the lungs, and lies at the right of the esophagus.
Study the structure and attachments of the diaphragm. It comprises a central V-shaped tendinous portion, surrounding which is a muscular region with fibers radiating from the central tendon to the adjacent body walls. Note the relative positions of the apertures through which the inferior vena cava, esophagus, and descending aorta penetrate the diaphragm. Observe the number and distribution of the phrenic veins which traverse the diaphragm, carrying blood from its substance to the inferior vena cava. Follow the inferior vena cava posteriorly from the diaphragm, exposing its tributaries, which are described below.
The hepatic veins convey the blood from the liver, which received it from the portal circulation and hepatic artery, to the inferior vena cava. The hepatic veins may be exposed by carefully chipping away the brittle tissue of the liver with a blunt instrument. Determine the number and location of these veins. The two renal veins, short but of large calibre, drain the blood from the kidneys into the
- ↑ Locate the sympathetic nervous system before dissecting the arteries and veins posterior to the heart. This system will probably be injured during the dissection.
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