Cranial nerves

Your brain uses special wires to talk to your body. These are called cranial nerves.

Unlike spinal nerves that come from your spinal cord, these emerge directly from the brain. Most of them come from the brainstem, which is the lower part of your brain. These nerves are very important for your special senses. They allow you to see, smell, taste, and hear. They also help you move your head and neck muscles.

These nerves work by carrying information back and forth. Some nerves carry signals from your senses to your brain. Other nerves carry signals from your brain to your muscles. For example, the facial nerve (VII) sends signals to the muscles in your face. This helps you make different expressions. The nerves are always paired. This means you have one on the left side and one on the right side. They travel through paths inside your skull called intracranial paths. Some travel on paths outside the skull called extracranial paths.

Scientists have studied these nerves for a very long time. They use Latin or Greek names for many of them. This is because Latin was the main language for science when they were first recorded. The names often describe what the nerve does or how it looks. The trigeminal nerve (V) is named for its three parts, which means triplets. The vagus nerve (X) is named because it has a wandering course through the body. The trochlear nerve (IV) is named after a pulley. These names help doctors and scientists all over the world understand each other.

There are twelve pairs of cranial nerves in most humans. They are labeled with Roman numerals from I to XII.

The olfactory nerve (I) helps you smell. The optic nerve (II) helps you see. The vestibulocochlear nerve (VIII) controls your hearing and balance. The nerves are numbered from the front of the brain to the back. The olfactory and optic nerves come from the cerebrum. The other ten pairs come from the brainstem. Some experts even suggest there might be a thirteenth pair called nerve zero.

To get to their destinations, these nerves must pass through the skull. The skull has many small holes called foramina. These holes act like tiny doorways for the nerves. Some nerves also use bony canals, which are long paths inside the bone. The facial nerve (VII) uses the stylomastoid foramen to reach your face. The hypoglossal nerve (XII) uses the hypoglossal canal in the occipital bone. The glossopharyngeal (IX), vagus (X), and accessory (XI) nerves all exit through the jugular foramen. These paths ensure every nerve reaches the right muscle or sense organ.