All cranial nerves (except I and II) arise from the brain stem, between dorsal and ventral portions, midbrain (III, IV), pons (V, VI, VII, VIII), and medulla (IX, X, XI, XII). Note that CN (V, VII, IX, X) are mixed cranial nerves. While CN (I, II, VIII) are purely sensory. In the other hand the purely motor nerves are CN(III, IV, VI, XI, XII).