Vessel
Sigmoid sinus
The curved dural outflow toward the jugular bulb
High-yield
Follow transverse sinus → sigmoid sinus → jugular bulb/internal jugular vein. The mastoid relationship is a key landmark, not a fixed safe distance from neighboring structures.
Overview
The transverse sinus turns into the sigmoid sinus as the channel leaves the tentorial attachment. Its curved path indents the temporal and occipital bones near the mastoid region. It then reaches the jugular bulb and internal jugular vein. The depth of the sinus and its distance from mastoid air cells vary.
Reference facts
- Origin
- Continuation of the transverse sinus near the posterior petrous/mastoid region.
- Course
- Curves downward in the sigmoid groove of temporal and occipital bones, medial to the mastoid region, then approaches the jugular foramen.
- Branches
- Receives variable cerebellar and meningeal tributaries and communicates through mastoid emissary veins. Superior petrosal inflow joins near the transverse–sigmoid transition.
- Drains to
- Jugular bulb and internal jugular vein at the jugular foramen.
Clinical correlation
Middle-ear or mastoid infection can extend to the adjacent venous system and cause lateral/sigmoid sinus thrombosis. Ear pain, headache and fever may occur; a distinctive swinging fever pattern is not required.
Frequently asked questions
Where does the sigmoid sinus originate?
The sigmoid sinus arises from the continuation of the transverse sinus near the posterior petrous/mastoid region.
Where does the sigmoid sinus drain to?
The sigmoid sinus drains to the jugular bulb and internal jugular vein at the jugular foramen.
What are the tributaries of the sigmoid sinus?
Receives variable cerebellar and meningeal tributaries and communicates through mastoid emissary veins. Superior petrosal inflow joins near the transverse–sigmoid transition.
What is the course of the sigmoid sinus?
Curves downward in the sigmoid groove of temporal and occipital bones, medial to the mastoid region, then approaches the jugular foramen.