There is a special set of nerves that originate from the brain itself inside the cranium of the skull. One of the most important cranial nerve is the Trigeminal nerve. It has three branches that are responsible for sensation to the head and face, but also motor function for chewing muscles. The information sent to the brain covers everything from temperature, pressure, proprioception, and pain. Compromise in the trigeminal nerve area can cause behavioural issues such as head shaking, head tossing, excessive chewing on the bit, difficulty bridling, sensitivity to the head/poll area, tensed muscles of the jaw to name but a few.