Left 0 Left　1 Left　2 Left　3
Right 0 (absent valve)        
Right 1 (unicuspid valve)

1

7

10

  
Right 2 (bicuspid valve)

1

6

34

Right 3 (tricuspid valve)      

1
Table 2: Number and type of morphological variation of the internal jugular venous valves present in the 60 subjects studied.