Before she died, Dr. West's Grandmother had a stroke.

Before she died, Dr. West's Grandmother had a stroke.  Following the stroke, she had trouble speaking because of the movements her mouth needed to make (although she still seemed to understand language).  She could still swallow, but had a lot of trouble taking pills.  In fact, she started having to have all medications given to her in liquid form instead of pills.  After hearing this, and without even having to look at her test results, her doctor knew that the stroke likely had damaged a cranial nerve (hint: it resulted in a specific movement issue). 

Which nerve did her doctor suspect and what do you think made him think this?