Definition of COUNTERBORE. : to form a counterbore in: enlarge (part of a hole) by means of a counterbore.ADVERTISEMENT.efinition of COUNTERBORE. 1. : a flat-bottomed enlargement of the mouth of a cylindrical bore. 2. : a drill for making a counterbore â compare countersink.
The vestibulocochlear nerve (auditory vestibular nerve) , known as the eighth cranial nerve, transmits sound and equilibrium (balance) information from the inner ear to the brain.
Each of the 12 cranial nerves has a specific function within the nervous system. 1  The olfactory nerve (I) carries scent information to the brain from the olfactory epithelium in the roof of the nasal cavity. 2  The optic nerve (II) carries visual information from the eyes to the brain.