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.
The cranial nerves appear in pairs at the bottom surface of the brain. Their functions vary, but main functions include muscle control, helping the brain interpret the five senses, and controlling glands in the human body.Each cranial nerve pair controls specific functions of the human body. The olfactory nerve is involved in the sense of smell. 2  This nerve has access to the cerebral cortex, but does not pass through the thalamus like other cranial nerves. 3  The optic nerve is involved in the sense of sight. 4  Responsible for vision, damage to this nerve can result in temporary or permanent blindness.