Cranial Nerves

The 12 pairs of nerves connected to the brain are known as cranial nerves (CN). The cranial nerves are both numbered and named. Roman numerals are always used to identify the number of a cranial nerve. The cranial nerves are numbered in the order that they attach to the inferior surface of the brain, starting with CN I at the cerebrum and ending with CN XII on the brain stem.

Each cranial nerve also has an individual name. The CN names indicate the general function of the nerve. Because it can be hard to remember the 12 individual cranial nerve names, a mnemonic for cranial nerve names is frequently used.

One way to learn the cranial nerves is to categorize them by functional type, that is, sensory, motor, or mixed nerves. Using a mnemonic for the cranial nerve types can help you learn this information.

• CN I: Olfactory nerve (sensory)
• CN II: Optic nerve (sensory)
• CN III: Oculomotor nerve (motor)
• CN IV: Trochlear (motor)
• CN V: Trigeminal (both sensory and motor: mixed)
• CN VI: Abducens (motor)
• CN VII: Facial (both sensory and motor: mixed)
• CN VIII: Vestibulocochlear (sensory)
• CN IX: Glossopharyngeal (both sensory and motor: mixed)
• CN X: Vagus (both sensory and motor: mixed)
• CN XI: Accessory (motor)
• CN XII: Hypoglossal (motor)

Figure 1: Overview of Cranial nerve numbers, names, and types