The cruciform eminence (or cruciate eminence) divides the deeply concave internal surface of the occipital bone into four fossae:

• The upper two fossae are called the cerebral fossae, are triangular and lodge the occipital lobes of the cerebrum.
• The lower two are called the cerebellar fossae, are quadrilateral and accommodate the hemispheres of the cerebellum.

The upper fossae are separated from the lower fossae by a groove for the transverse sinuses. At the point of intersection between all four fossae is the internal occipital protuberance.

• 
  Cerebral fossa (shown in red)
• 
  Cerebellar fossa (shown in red)

This article incorporates text in the public domain from page 130 of the 20th edition of Gray's Anatomy (1918)