Question

a lesion to the glossopharyngeal nerve (cn 9) could impair which function?
eye movement
salivation
facial sensation
tongue movement

Explanation:

The glossopharyngeal nerve (CN 9) has several functions. One of its key functions is related to salivation. It innervates the parotid gland which is involved in saliva production. Eye movement is mainly controlled by oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves. Facial sensation is primarily the domain of the trigeminal nerve (CN V). Tongue movement is mainly under the control of the hypoglossal nerve (CN XII).

Answer:

Salivation