What is the location of the sigmoid sinus?

Sigmoid Sinus Location

The sigmoid sinus is located in the posterior cranial fossa, extending from the transverse-sigmoid sinus junction to the jugular bulb, coursing along the inner surface of the temporal and occipital bones. 1

Anatomical Position and Course

• The sigmoid sinus is a continuation of the transverse sinus, beginning at the transverse-sigmoid sinus junction 1
• It follows an S-shaped course (hence the name "sigmoid") through the posterior cranial fossa 2
• The sinus terminates at the jugular bulb, where it transitions into the internal jugular vein 1, 3
• It is situated between the temporal and occipital bones, within a groove on the inner surface of the skull 1, 3

Anatomical Relationships

• The sigmoid sinus is positioned posterolateral to the foramen magnum 2
• It is adjacent to the mastoid portion of the temporal bone 3
• The horizontal part of the sigmoid sinus runs roughly parallel to the line between the digastric point and posterior edge of the occipital condyle 4
• The sinus is covered by dura mater and contains venous blood 1

Clinical Significance

• The sigmoid sinus is an important venous drainage pathway for the brain 1
• It can be visualized on imaging studies such as MRI, MRV, and CT venography 1
• Postgadolinium 3-D MRI images show detailed anatomy of the transverse and sigmoid dural venous sinuses 1
• Abnormalities of the sigmoid sinus, such as sigmoid sinus wall abnormalities (SSWA) and sigmoid sinus diverticulum, can cause pulsatile tinnitus 1
• The sigmoid sinus is an important landmark during posterior fossa surgical approaches, particularly the retrosigmoid approach 3

Imaging Visualization

• On MRI, the sigmoid sinus appears as a flow void on T2-weighted images when patent 1
• MR venography (MRV) with IV contrast is an excellent tool for visualizing the sigmoid sinus 1
• CT venography can also provide detailed visualization of the sigmoid sinus 1
• Flair MRI may show hypersensitivity signal at the sigmoid sinus in cases of thrombosis 1

Surgical Considerations

• Exposure of the sigmoid sinus is an important step in presigmoid surgical approaches 3
• The sigmoid sinus can be safely exposed from the transverse-sigmoid junction to the jugular bulb 3
• Meningiomas can occur at the transverse-sigmoid sinus junction area 5
• Various anatomical landmarks have been described to locate the transverse-sigmoid sinus junction, with varying degrees of accuracy 6

Pathological Considerations

• Thrombosis of the sigmoid sinus can lead to venous infarction and intracranial hypertension 1
• Temporal lobe parenchymal changes on imaging often correspond to lateral (transverse) and sigmoid sinus thrombosis 1
• Anatomical variations of the sigmoid sinus can occur, including aberrant venous sinuses connecting to the sigmoid sinus 2