The skull is often somewhat flattened in the neighborhood of the parietal foramina, and the term obelion is applied to that point of the sagittal suture which is on a level with the foramina.    From Wordnik.com.  [II. Osteology. 5c. The Exterior of the Skull] Reference

An additional fontanelle is sometimes seen in the sagittal suture at the region of the obelion.    From Wordnik.com.  [II. Osteology. 5d. The Interior of the Skull] Reference