Which cranial nerves are purely sensory?

• A. Olfactory, Optic and Vestibulocochlear
• B. Trigeminal, Glossopharyngeal and Vagus
• C. Oculomotor, Trochlear and Abducens
• D. Vestibulocochlear, Glossopharyngeal and Accessory

Answer: (A)

Some cranial nerves are purely sensory; they carry only sensory information from their specialised modalities to the brain, with no motor output.

The olfactory nerve transmits smell from the nasal mucosa. The optic nerve carries visual information from the retina. The vestibulocochlear nerve handles hearing and balance from the inner ear. These nerves do not have motor fibers, so they are classified as purely sensory.

Other cranial nerves combine sensory and motor functions or are primarily motor for eye movement. The trigeminal nerve provides facial sensation and also motor to the muscles of mastication. The glossopharyngeal and vagus nerves carry sensory and motor (including parasympathetic) fibers to and from the head and thorax/abdomen regions. The oculomotor, trochlear, and abducens nerves are primarily motor to the extraocular muscles (with some proprioceptive input), not purely sensory.