Inferior sagittal sinus
Sinus sagittalis inferior
A small midline dural venous sinus running along the free lower edge of the falx cerebri, above the corpus callosum.
At a glance
- English
- Inferior sagittal sinus
- Latin (TA2)
- Sinus sagittalis inferior
- System
- Vein
- Region
- Head
- Side
- Single, on the midline
About the inferior sagittal sinus
The inferior sagittal sinus, sometimes called the inferior longitudinal sinus, is a slender venous channel in the free lower margin of the falx cerebri, the sickle-shaped fold of dura that hangs down between the two cerebral hemispheres. Unlike the superior sagittal sinus, which lies against the skull along the attached upper edge of the falx, this one hangs free within the head, arching above the corpus callosum.
It runs from front to back, growing gradually as it goes, along the rear two-thirds or so of the falx. At the back it reaches the place where the falx joins the tentorium cerebelli. There it meets the great cerebral vein, which brings blood from the deep parts of the brain, and the two together form the straight sinus.
Its tributaries are veins from the falx itself and veins from the medial and deep surfaces of the cerebral hemispheres, including some from the corpus callosum and the cingulate gyrus. It is much smaller than the superior sagittal sinus and has no arachnoid granulations draining into it, so it plays little part in the return of cerebrospinal fluid.
From the straight sinus its blood passes into the confluence of sinuses near the internal occipital protuberance and then, mostly by the left transverse sinus, on to the sigmoid sinus and the internal jugular vein. Clinically, the sinus can be involved in cerebral venous thrombosis, usually as part of a clot affecting the deep venous system, and it is seen on venous imaging of the brain as a fine curved line above the corpus callosum.
Course and drainage
- Begins at
- Begins in the free lower margin of the falx cerebri, from veins of the falx and the medial cerebral surface.
- Drains into
- Joins the great cerebral vein at the junction of the falx and tentorium to form the straight sinus.
- Drains
- Drains the falx cerebri and the deep and medial parts of the cerebral hemispheres.
Anthromica
See the inferior sagittal sinus where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
