There is abnormal dilatation of right internal jugular vein during Valsalva for a length of 8cm in the lower 2/3rd of neck, starting from C4 vertebra upto the formation of right brachiocephalic vein.
Rest Valsalva.
Anteroposterior diameter of right internal jugular vein 13 mm 32 mm
Anteroposterior diameter of left internal jugular vein 9 mm 20 mm