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.
Cranial nerve VIII, the acoustic nerve, has sensory function only and is tested by checking hearing. This can be accomplished in a number of ways. A common method is the whisper test. Stand behind the patient, have him cover one ear, then whisper a few words and ask him to repeat them. Repeat on the other side.