Intermediate Sigmoid Sinus Quiz

Q1. Why is this dural venous channel called the sigmoid sinus?

• It follows the optic nerve
• It divides into paired arteries
• It surrounds the sella turcica
• It follows an S-shaped course

Q2. What is the name of the bony groove occupied by the sigmoid sinus?

• Carotid sulcus
• Chiasmatic sulcus
• Precentral sulcus
• Sigmoid sulcus

Q3. Which emissary vein commonly connects the sigmoid sinus with extracranial veins through the mastoid region?

• Great cerebral vein
• Central retinal vein
• Mastoid emissary vein
• Superior ophthalmic vein

Q4. Which extracranial venous network may communicate with the distal sigmoid and jugular region through condylar emissary veins?

• Vertebral and deep cervical venous networks
• Portal venous system
• Coronary venous sinus
• Pulmonary venous network

Q5. Why can flow through emissary veins connected to the sigmoid sinus reverse direction?

• They are branches of the external carotid artery
• They are generally valveless
• They contain one-way arterial valves
• They are disconnected from extracranial veins

Q6. What normally separates the sigmoid sinus from nearby mastoid air cells?

• The optic nerve sheath
• The falx cerebri
• A variable bony plate
• The diaphragma sellae

Q7. Which venous expansion is continuous with the distal sigmoid sinus at the jugular foramen?

• Carotid bulb
• Cavernous sinus
• Inferior sagittal sinus
• Superior jugular bulb

Q8. How does the wall of the sigmoid sinus differ from that of a typical vein?

• It is lined by respiratory epithelium
• It contains elastic lamellae like the aorta
• It is formed between dural layers rather than having a typical muscular venous wall
• It is surrounded by thick cardiac muscle

Q9. Which upstream sinus delivers most venous blood directly into the sigmoid sinus?

• Inferior sagittal sinus
• Sphenoparietal sinus
• Transverse sinus
• Intercavernous sinus

Q10. Why is the position of the sigmoid sinus important during mastoid surgery?

• It forms the tympanic membrane
• It transmits the internal carotid artery
• It contains the facial motor nucleus
• Its variable proximity to the mastoid surgical field creates a risk of venous injury