cranial nerves

There are 12 paired cranial nerves that exit the skull under the brain's surface that extend to various parts of the head, neck, chest and abdomen. The cranial nerves comprises three nerve types motor nerves that send an impulse signal to a muscle sensory nerves that transmit sensations from the body back to the brain and autonomic nerves with both motor and sensory components that monitor and control visceral functions such as salivation, heart rate and intestinal movement. The cranial nerves are numbered one through 12 and are referred to by either their name or number.

1  The Olfactory Nerve
The olfactory nerve is a sensory nerve that receives and transmits the sense of smell from the nose and sinuses back to the brain. It is located under the frontal lobes of the brain and perforates the skull at the cribiform plate.

2 - The Optic Nerve
The optic nerve is a sensory nerve responsible for vision. It transmits signals from the retina in the eye back to the visual cortex in the posterior lobes of the brain traversing the skull through the optic canal.

3 - The Oculomotor Nerve
The oculomotor nerve traverses the skull through the superior orbital fissure and is both a motor and autonomic nerve. The motor portion transmits signals from the brain that result in eye movements. The autonomic portion controls constriction and dilation of the pupil and prevents the upper eyelid from drooping.

4 - The Trochlear Nerve
The trochlear nerve is a motor nerve that sends signals from the brain causing the eye to move in the downward and inward directions. The trochlear nerve also traverses the skull through the superior orbital fissure.

5  The Trigeminal Nerve
The trigeminal nerve is the largest of the 12 cranial nerves and is both a motor and sensory nerve. The motor portion of the trigeminal nerve is responsible for jaw movement and chewing, while the sensory portion of the nerve provides the sensation of touch over the face as well as on the surface of the eye. There are three major branches of the trigeminal nerve--the ophthalmic branch, the maxillary branch and the mandibular branch, which each traverses the skull in different locations.

6  The Abducens Nerve
The abducens nerve is a motor nerve that is responsible for lateral or outward eye movement. It traverses the skull through the superior orbital fissure.

7  The Facial Nerve
The facial nerve traverses the skull through the internal auditory canal and has all three nerve type components motor, sensory and autonomic. The motor portion is responsible for facial movements and expression, as well as some muscles deep in the neck. The sensory portion is responsible for registering taste on the anterior two- thirds of the tongue. The autonomic portion monitors and controls moisture of the eyes as well as salivation.

8  The Auditory Nerve
The auditory nerve is also known as the vestibulocochlear nerve and has both sensory and autonomic nerve characteristics. The cochlear portion is sensory, innervating the inner ear and is responsible for hearing. The vestibular portion is autonomic, innervating a different portion of the inner ear and is responsible of the sense of balance. The auditory nerve also exits the skull via the internal auditory canal.

9  The Glossopharyngeal Nerve
The glossopharyngeal nerve exits the skull via the jugular foramen carrying motor, sensory and autonomic nerve types. The motor portion innervates muscles of the neck responsible for swallowing and speech. The sensory portion transmits taste and touch from the posterior one-third of the tongue as well as sensation of a portion of the ear. The autonomic portion monitors and controls dilatation of a portion of the carotid artery in the neck and thereby has an influence on blood pressure.

10  The Vagus Nerve
The vagus nerve exits the skull through the jugular foramen as well and is also composed of motor, sensory and autonomic nerve types. The motor portions innervate muscles of the throat that aid in swallowing and speech. The vagus nerve supplies sensory information from the throat and is responsible for the gag reflex. The autonomic portion extends nerves to regions of the aorta in the chest that monitor blood pressure and to nerves in the abdomen that monitor and control bowel function.

11  The Spinal Accessory Nerve
The spinal accessory nerve is a motor nerve that innervates and causes movement of the sternocleidomastoid muscle in the neck and the trapezius muscle in the upper back resulting in shrugging. It also exits the skull via the jugular foramen.

12  The Hypoglossal Nerve
The hypoglossal nerve is a motor nerve that innervates the muscles of the tongue responsible for tongue movement. It traverses the skull through the hypoglossal canal.

Mammalian Respiration - Nerve Effects

Vagus Nerve Stimulation VNS

 Is now being used for depression, seizures and eating disorders. Although the precise mode of action of VNS is not known, researchers suggest that VNS increases seizure threshold by causing widespread release of GABA and Glycine in the brain. Reported changes in blood flow in the cerebellum, thalamus and cortex might activate inhibitory structures in the brain reducing seizure kindling. One VNS study showed mean seizure frequency to decrease by 25%. Altered synaptic activities at sites of persisting VNS-induced cerebral blood flow changes may reflect antiseizure actions. 

Depression affects some 340 million people worldwide and there is a correlation between depression and the likelihood of developing seizures. VNS increases cognitive skills reflecting a reduction in depression. Areas of the brain that are affected by Vagus Nerve Stimulation include the medulla, cerebellum, parabrachial nucleus, locus ceruleus, hypothalamus, thalamus, amygdala, hippocampus and cingulated gyrus. Noradrenergic and/or serotonergic deficits, may contribute to predisposition to some epilepsies and depressions. Evidence suggests that vagus nerve stimulation exerts at least some of its anticonvulsant and antidepressant effects through its capacity to increase noradrenaline and serotonin transmission.

The vagus is responsible for keeping the larynx open for breathing and also feeds the lungs and diaphragm. Deep breathing stimulates the vagus nerve bringing balance between the parasympathetic and sympathetic nervous systems. Since a VNS device and its surgical implantation will run at nearly $30,000 it's an expensive treatment for seizure, compulsiveness and depression.breathing however does a similar job of activating the vagus nerve and it's free.

The sense of contraction and pain in the core of ones torso and neck during the heating phase prior to popping is obviously the vagus nerve making a valiant effort to counter the revving up of the pituitary-adrenal-axis, and the sympathetic nervous system. The vagus is trying to keep the emotional-memory arousal faculties of the body repressed; hence we feel this conflict as a persistent tension in our core for up to 2 years prior to awakening.

Besides breathing it is also possible to stimulate the vagus into relaxing the body-core by turning the minds eye into ones center and actively warming and purposefully letting the area go. All thoughts, emotions and phenomena are drawn into ones core as though one is an atomic karmic disposal unit. We could call this practice Melting In The Coreturning the minds eye into actively stimulating the vagus nerve into relaxing the viscera. This alleviates depression, increases coherency, lucidity, makes for a more vibrant personality and improves health and well-being.

Scientists are investigating the existence of non-genital orgasms suggesting a more pervasive orgasmic process and its role in neuroendocrine and psychological health. There are vaginocervical sensory pathways to the brain that can produce the absence of pain without loss of consciousness analgesia, release oxytocin, and bypass the spinal cord via the vagus nerve. That is a paraplegic woman can still have cervical and G spot orgasms because the vagina is fed by the vagus nerve while the clitoris by nerves that come out of the spine. This gives weight to the necessity of sexual intercourse for maintaining healthy balance of the nervous system. Also there might be something to the validity of having sex during an awakening to help the parasympathetic nervous system to maintain its own. Orgasm has been described as a mini-seizure of the limbic system and tends to release or lessen deep limbic activity. Dr Amen noticed that depression, sadness, feelings of hopelessness, and automatic negative thoughts correlate with a hyperactive limbic area. The supplements that seem to help limbic hyperactivity best are DL-phenylalanine (DLPA), L-tyrosine, and S-Adenosyl-Methionine (SAMe).

I find it fascinating that the parasympathetic off-switch vagus turns on activating neurotransmitters in the emotional memory systems...obviously this is a big factor in the reward/punishment building of our response system. One of the contributors to the tenacity of PTSD as well no doubt, and you know they give norepinephrine blockers to trauma victims to block the vividness of their memory.

Because stimulation of the vagus nerve activates the memory centers in the brain it is apparent that sex would be good for improving memory ability. Since memory is primary to our sense of meaning and to cognition in general, it is apparent that sex has the potential of improving intelligence and quality of life through improved brain function and freedom from depression. The counter argument to this is that the endorphins produced during sex would reduce mental alertness.

Retraining the Vagus Lie flat on your stomach with your head to one side. Progressively relax your jaw by imagining it dropping down toward your feet. You will notice that this stimulates breathing, for you get the sense of oxygen hunger. Obviously a tight jaw is tied into the neural circuits for the suspension of breath and shallow breathing. Repeating this exercise and making this jaw-contraction more conscious will help to retrain the medulla and vagus toward deeper breathing and change the set point of the nervous system toward greater relaxation. That is, bringing consciousness to contracted tissue helps to get rid of the inefficient fossilized tension that perpetuates itself for no good reason.