Pathologic conditions of the lower cranial nerves IX, X, XI, and XII.

The glossopharyngeal, vagus, spinal accessory, and hypoglossal cranial nerves can be affected by an acute or chronic process that has an impact on the way the patient presents clinically. Knowledge of nerve pathways and relations to surrounding structures is fundamental when evaluating patients who have lower cranial nerve symptoms. A systematic "segment-based" approach helps to narrow the differential diagnosis Pathologic conditions that cause lower cranial nerve symptoms are presented.