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 nuclei of the glossopharyngeal nerve (IX), vagus nerve (X), accessory nerve (XI) and hypoglossal nerve (XII) are located in the medulla. The fibers of these cranial nerves exit the brainstem from these nuclei. Function. There are three main functions of the brainstem: The brainstem plays a role in conduction.