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 vagus nerve innervates the larynx, the pharynx, the upper part of the oesophagus, the part of the external hearing apparatus, the heart, the lungs, the stomach, the intestine and even several muscles. The accessory nerve, known as the eleventh cranial nerve, is a motor nerve, that regulates the muscular activity.he vagus nerve, or tenth cranial nerve, is the longest and most important nerve of the parasympathetic nervous system (it belongs to the neurovegetative system) as it regulates the functions of almost all of the internal organs.