Petrosus

Petrosus is a Latin adjective meaning rocky or stony. In scientific usage, it appears in anatomical and paleontological terms to denote structures associated with the petrous part of the temporal bone, and more broadly as a descriptive epithet in Latin binomials.

In anatomy, the pars petrosa, or petrous part of the temporal bone, is a thick, dense region at the base of the skull. It forms the internal protection for crucial components of the auditory and vestibular systems and contributes to the enclosure of the inner ear. The petrous portion houses structures such as the bony labyrinth and the pathways for several nerves, including the routes that pass through the internal acoustic meatus and other openings in this region.

Two nerves commonly linked by the name petrosus are the greater and lesser petrosal nerves. The nervus petrosus major, or greater petrosal nerve, arises from the facial nerve (CN VII) and carries parasympathetic fibers toward the pterygopalatine ganglion, among other targets. The nervus petrosus minor, or lesser petrosal nerve, is associated with the glossopharyngeal nerve (CN IX) and contributes parasympathetic fibers toward the otic ganglion. Both nerves derive their names from their intimate relationship with the petrous portion of the temporal bone.

In paleontology and comparative anatomy, the petrosal bone refers to the otic region within the temporal area of skulls. The petrosal component is a key feature in many mammalian skulls and is often analyzed in studies of skull evolution and auditory capability.

Etymology and related terms include pars petrosa (petrous part), petrous bone, and the general use of petrosus as a descriptor in anatomical nomenclature. See also: temporal bone, internal acoustic meatus, greater petrosal nerve, lesser petrosal nerve.