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.  The optic nerve (II) carries visual information from the eyes to the brain.