• (a.) Of or pertaining to the petrous and mastoid parts of the temporal bone, periotic.
(pet″ro-mas´toid) pertaining to the petrous part of the temporal bone and its mastoid process. otocranium (def. 2).
Pet`ro·mas'toid adjective [ Petro + mastoid .] (Anat.) Of or pertaining to the petrous and mastoid parts of the temporal bone, periotic. 
Type: Term Pronunciation: pet′rō-mas′toyd Definitions: 1. Relating to the petrous and the squamous portions of the temporal bone, which are usually united at birth by the petrosquamosal suture. Synonyms: petrosomastoid