Paired and Unpaired Sinuses

# Which one of the following is an unpaired sinus?
A. Cavernous sinus
B. Sigmoid sinus
C. Straight sinus
D. Superior petrosal sinus

The correct answer is C. Straight Sinus.

Venous sinuses of dura mater are:

Paired - 1. Cavernous sinus, 2. Superior petrosal sinus, 3. Inferior petrosal sinus, 4. Transverse sinus, 5. Sigmoid sinus, 6. Sphenoparietal sinus, 7. Petrosquamous sinus, 8. Middle meningeal sinus

Unpaired:

1. Superior sagittal sinus, 2. Inferior sagittal sinus, 3. Straight sinus, 4. Occipital sinus, 5. Anterior intercavernous sinus, 6. Posterior intercavernous sinus, 7. Basilar plexus of veins, 8. Sphenoid air sinus