Groove for marginal sinus

The groove for marginal sinus is located on both sides of the edges of the foramen magnum. These grooves extend from the occipital sinus groove, which runs along the internal occipital crest and turns into a shallow depression known as the vermian fossa when it reaches the posterior margin of foramen magnum. From there, the groove for occipital sinus splits into two, forming the marginal sinus grooves on each side of the foramen magnum.