Corpus: Petrous bone

The petrous portion of temporal bone or in Latin Pars petrosa ossis temporalis is a pyramid-shaped section of bone at the base of the temporal bone (Os temporale) that contains the inner ear.

In contrast to some animal species, the temporal bone in humans is not an independent bone, but part of the temporal bone. Therefore, the correct term is Pars petrosa ossis temporalis. The terms "Os petrosum" or "petrous temporal bone" used in clinical parlance are therefore not actually correct.

Overview[Bearbeiten]

The petrous bone has the basic shape of a three-sided pyramid and is located at the base of the skull between the sphenoid bone and the occipital bone. Its tip is directed medially and rostrally.

There is a base and a tip (apex) of the petrous bone, as well as three surfaces (facies) and three angles (anguli). The osseous structures of the inner ear, the bony labyrinth, are formed inside the petrous bone.

The base of the petrous bone is fused with the inner surface of the pars squamosa and the pars mastoidea of the temporal bone.

The apex, also known as the tip of the petrous bone, is rough and uneven. It fits into the angle between the posterior edge of the greater ala of the sphenoid bone and the basilar part of the occipital bone. It surrounds the internal orificium of the carotid canal and forms the posterolateral edge of the lacrimal foramen. This is where the sphenopetrous ligament (Gruber ligament) attaches.

The petrous bone is present throughout life as a plexus bone and is not remodelled into lamellar bone. The pars petrosa ossis temporalis is the hardest bone in the human skull.

Bone canals[Bearbeiten]

Various bone canals run through the petrous bone. These include, among others:

• Canalis caroticus: Contains the internal carotid artery
• Meatus acusticus internus: Carries the vestibulocochlear nerve and other structures
• Canalis nervi facialis: Carries the facial nerve
• Canalis musculotubarius: Contains the tensor tympani muscle and the auditory tube
• Canaliculus vestibularis: For the endolymphatic duct
• Canaliculus tympanicus: Carries the tympanic nerve and the inferior tympanic artery
• Canaliculi caroticotympanici: Contains the arteriae and nervi caroticotympanici

The petrous temporal bone can be injured in skull injuries. Fractures of the petrous bone are usually burst fractures in the context of polytrauma or traumatic brain injury.