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.
Function of Cranial Nerves. 1  Vagus Nerve: Smooth muscle sensory and motor control in throat, lungs, heart, and digestive system. 2  Accessory Nerve: Movement of neck and shoulders. 3  Hypoglossal Nerve: Movement of tongue, swallowing and speech.