Squamous tympanic petrous styloid process mastoid process The squamous plate form the lateral side of the skull superiorly with the parietal bone by the squamosal suture anteriorly and inferiorly with the greater wing of sphenoid bone posteriorly continued with the mastoid process superior and inferior temporal lines a single line from the posterior margin of the zygomatic process of the frontal bone and diverge as they arch backward the zygomatic process projected from its middle part of outer surface this process with the temporal process of zygomatic bone formed zygomatic arch. The temporal fossa The squamous plate formed the medial wall laterally zygomatic arch superiorly superior temporal line inferiorly infratemporal crest The inner surface the lateral wall of the medial cranial fossa with the greater wing of sphenoid bone and the parietal bone petrous and the greater wing of sphenoid bone formed the floor of the medial cranial fossa On the lateral surface of the squamous tympanic plate the suprameatal crest the suprameatal triangle the suprameatal spine The mandibular fossa Anterior to the fossa a small elevation called articular tubercle Posteriorly squamotympanic fissure separating the fossa from the tympanic plate through the medial end of the fissure, which the chorda tympani exits from the tympanic cavity The tympanic part C shaped on section and forms the bony part of the external auditory meatus The petrous anteriorly by greater wing of sphenoid bone and separated by groove for the cartilaginous part of the auditory tube. Medially bounded by the basilar part of the occipital bone. Laterally bounded by styloid process. The foramen lacerum At the medial end is irregular and, together with greater wing of sphenoid bone and the basilar part of the occipital bone close with time by cartilage and fibrous tissue the apex of the petrous and the sphenoid bone only a few vessels pass through this foramen from the medial cranial fossa to the neck. On the inferior surface the side of the foramen lacerum above the closed inferior opening The carotid canal The internal carotid artery an irregularly shaped pyramidal mass The superior borders of the petrous anteriorly bounded the middle cranial fossa posteriorly bounded the posterior cranial fossa anteriorly. Lateral to the foramen lacerum is an impression on the apex of the petrous for the trigeminal ganglion. On the anterior surface are two groove for nerves the largest medial groove is for the greater petrosal nerve the smaller lateral groove is for the lesser petrosal nerve The arcuate eminence rounded eminence found on the anterior surface of the petrous and is caused by the underlying superior semicircular canal. The internal auditory meatus the 7th and 8th cranial nerves the internal auditory branch of the basilar artery. At posterior surface Inferomedially the petrous part articulates the condylar part of the occipital bone except where it forms the anterolateral boundary of the jugular foramen the inferior petrosal sinus, 9th, 10, and 11th cranial nerves, and the sigmoid sinus the internal ear The tegmen tympani laterally formed the roof of middle ear, which is thin plate of bone Anteriorly formed the roof of the auditory (Eustachian) tube posteriorly formed the roof of the mastoid antrum It separates the middle ear from the middle cranial fossa. The mastoid antrum behind the middle ear in the petrous communicates with the middle ear by aditus The styloid process a base, which is embedded between the petrous and tympanic part the free portion which is directed downward and forward and medially for a varying distance The mastoid process projects posterior to the styloid process downward and forward forward formed the greater part of the subcutaneous surface of the temporal bone behind the external auditory meatus part of the lateral wall of the posterior cranial fossa grooved by the sigmoid sinus The mastoid process is undeveloped in the newborn child and grows only as result of the pull of the muscle, as the child moves the head. It can be recognized as a bony projection at the end of the second year. Medial to the tip of the mastoid process there is a notch. The occipital artery lies in a groove medial to the notch. The superior and posterior borders are serrated and articulated with the parietal and occipital bones respectively. The mastoid air cells a series of communicating cavities within the mastoid process that are continuous above with the mastoid antrum and the middle ear The stylomastoid foramen The interval between the styloid and mastoid processes the 7th cranial nerve the stylomastoid branch of the posterior auricular artery