Inferior view of left temporal bone. The squamous portion of the temporal bone is located anterior to the tympanic part and contains the mandibular fossa on its inferior surface for the condyle of the mandible (temporomandibular joint). A slender process extends forward as the zygomatic process. This unites with the temporal process of the zygomatic bone to form the zygomatic arch. The posterior wall of the mandibular fossa borders on the front of the bony external auditory canal formed by the tympanic part of the temporal bone. The mastoid portion is located immediately posterior to the tympanic part and features the mastoid process containing air cells and antrum, the mastoid notch or digastric groove for attachment of the posterior digastric muscle, and the groove for the occipital artery. The petrous portion is pyramidal in shape with an apex that projects anteromedially and a base that is directed laterally and fuses to the squamous and mastoid parts. The petrous part is wedged between the sphenoid and occipital bones and forms boundaries with the middle and posterior cranial fossae. Its inferior surface includes the stylomastoid foramen (at the base of the styloid process) for passage of the facial nerve and stylomastoid artery, the jugular fossa on which rests the jugular bulb , and carotid canal for passage of the internal carotid artery.  (Image courtesy of AL Rhoton, Jr.)