Pneumatization of the mastoid and petrous portions of the temporal bones begins late in fetal life, accelerates near and immediately after birth, and continues through infancy, early childhood, and, occasionally, early adult life. This pneumatization can vary greatly, and in cases of well-pneumatized temporal bones, accessory occipital air cells may occur and communicate with the mastoid air cells and middle ear. Other accessory sites of air cell pneumatization include the zygomatic process, squamosal region, and styloid process of the temporal bone.1 Pneumatization of the occipital bone, including the craniocervical junction, is rare and, to our knowledge, has previously been reported only 10 times.2- 10 In 4 of those cases,2,7,8 there was a history of trauma.
Moreira B, Som PM. Unexplained Extensive Skull Base and Atlas PneumatizationComputed Tomographic Findings. Arch Otolaryngol Head Neck Surg. 2010;136(7):731-733. doi:10.1001/archoto.2010.108