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the opening of pre caval/superior venacave/ in right auricle is guarded by haversian valve. . .dont get confused by haversian system found in bone
Haversian Canals
That is 'aversion'.
Haversian canals branch into the compact bone, they caring blood vesels which nourish the osteocytes.
The Haversian canals carry blood vessels and nerves to and from the bone.