To recap, pressure or a tug on the membrane system (meninges), which envelops the brain and spinal cord (CNS) as one unit, anywhere from the top of the head to the bottom of the spine (please see installments three, four, and five) may produce a myriad of symptoms, such as impaired vision, headaches, difficulty with hearing and balance, nausea, digestive upset, impaired speech, difficulty breathing, and many more. So will trauma to the head as well as the spine. (See the FIRST and SECOND INSTALLMENT.). How can that be?
The cranium has many openings (foramina) through which the cranial nerves, one through twelve (I-XII), exit the skull. A shifting of the skull bones may change the shape and size of the foramina and distort the meninges lining the inside of the skull, thus compressing or stretching the cranial nerves as they pass through these openings. Know that the cranial nerves have to pass through the membrane, as well as the foramina of the cranium.
We all know that tight muscles or dislocated vertebrae parking on our nerves may produce tremendous pain, as well as dysfunction in the structures that the nerves innervate. The same is true regarding the cranial nerves. Any trauma to these nerves will result in dysfunction of the structures that they innervate, as well as pain or discomfort. Below is a list of the twelve cranial nerves and their functions.
Cranial nerve I (olfactory nerve) allows us to smell.
Cranial nerve II (optic nerve) allows us to see.
Cranial nerves III, IV, VI (oculomotor, trochlear, and abducens nerves) supply the muscles that move the eyes.
Cranial nerve V (trigeminal nerve) supplies the sensory nerves of the face, as well as the muscles involved in chewing (mastication).
Cranial nerve VII (facial nerve) primarily supplies the muscles of expression in our face.
Cranial nerve VIII (vestibulocochlear nerve) allows us to hear and maintain balance.
Cranial nerve IX (glossopharyngeal nerve) gives sensation to the posterior one third of the tongue, the tonsils, pharynx, and middle ear, as well as allows us to swallow and produce saliva.
Cranial nerve X (the famous vagus nerve) innervates the larynx, trachea, bronchi, lungs, heart, digestive tract (from the mouth to the first one third of the large intestine), as well as the external ear.
Cranial nerve XI (accessory nerve) allows us to turn our head and tilt it to the side, as well as raise and lower our shoulders.
Cranial nerve XII (hypoglossal nerve) primarily supplies the tongue muscles for speech and moving food to the back of the mouth for swallowing.
So, there you have it in a nutshell: If your brain gets hurt, you will hurt, too, although not always the way you would expect it. However, knowing that these cranial nerves are extensions of the brain that find their way into the body through the bony labyrinth of your skull helps to understand why we feel the way we do when we sustain injury to the face or head.
The spinal nerves are extensions of the brain as well. They leave the cranium via the spinal cord. For more, read the SEVENTH INSTALLMENT….