Definition of petrosal in English:



  • The dense part of the temporal bone at the base of the skull, surrounding the inner ear.

    • ‘In pakicetids, the ectotympanic has already overgrown, giving rise to a large bulla surrounding the petrosal.’
    • ‘In the region of the ear, the tympanic bone is semicircular, and the petrosal is massive and only loosely bound to the basicranium.’
    • ‘The otic capsule became somewhat separated from the rest of the braincase as a pair of petrosals.’
    • ‘Even more so than in Morganucodon, the anterior lamina of the petrosal is medially convex, leaving deep fossa for the semilunar ganglion, the root node of the trigeminal nerve.’
    • ‘Minimum basioccipital width is narrow relative to cavity width, suggesting the petrosals would have been moderately enlarged (in width two to three times the shortest distance between them).’


  • Relating to or denoting the petrosal, or the nerves which pass through it.

    • ‘The temporal lobe, now slack from the mannitol, is retracted from the bone of the middle fossa floor, with care taken not to cause traction on the greater superficial petrosal nerve.’
    • ‘A foramen may be present in the petrobasilar fissure in front of the jugular foramen through which runs the inferior petrosal sinus.’
    • ‘Impulses are conveyed via the glossopharyngeal nerve then via its tympanic branch to the tympanic plexus thence to the otic ganglion via the lesser superficial petrosal nerve.’
    • ‘If the results of the work-up to this point are equivocal or the work-up suggests ectopic ACTH production, inferior petrosal sinus sampling is indicated.’
    • ‘Drilling begins directly over the bisection of the angle between the greater superficial petrosal nerve and arcuate eminence and the dura of IAC is exposed beneath the petrous ridge.’


Mid 18th century: from Latin petrosus ‘stony, rocky’ (from petra ‘rock’) + -al.