The 12 Cranial Nerves

Edited by Sterling Precision Nelson

Cranial Nerve I: Olfactory Nerve

Type of Nerve: Sensory ​ Function of Nerve: Sense of Smell ​

Brief description: The Olfactory Nerve is the first of the 12 pairs of cranial ​ nerves in the brain. It’s a sensory nerve, in charge of transmitting olfactory stimuli from the nose to the brain, Its actual origin is given by the cells of the olfactory bulb and is the shortest cranial pair of all of the pairs in the brain.

Important side note: Damaged olfactory nerve cells can regenerate, but don’t ​ ​ always reconnect properly in the brain.

Name Nerve Disorder Treatment

Dysnomia - Parosmia Distortion of smelling that No specific cure refers to the perception of available, but symptoms the smell. lessen over time, in some patients it may take years.

Dysnomia - Phantosmia Distortion of smelling that Can recover easily if it refers to a smell not from sickness however present. rinsing out the sinus with saline solution will help treat the problem.

Hyposmia A decreased ability to there's no known cure or smell. treatment for congenital anosmia.

Anosmia A total inability to smell. there's no known cure or treatment for congenital anosmia.

Cranial Nerve II: Optical

Type of Nerve: Sensory ​ Function of Nerve: Vision ​

Brief description: The Optical cranial pair is the second of the 12 pairs of cranial ​ nerves and it is responsible for conducting visual stimuli from the eye to the brain. It is made of axons from the ganglion cells of the retina, that take the information of the photoreceptors to the brain, where later it will be integrated and interpreted and It emerges in the diencephalon.

Name Nerve Disorder Treatment

Hereditary Optic Vision loss, Nystagmus No effective treatment, Neuropathies hearing loss and possible however limiting tobacco trouble distinguishing and alcohol slow the rate shades of blue and yellow of the vision loss, colors that they see. magnifiers and vision aids help as well.

Ischemic Optic Vision loss, Giant cell Controlling blood Neuropathy arteritis, blockage in pressure and diabetes, arteries. High doses of corticosteroids by mouth or vein.

Optic Neuritis Multiple sclerosis, loss of Corticosteroid, relief of vision. pressure if tumor is present, magnifiers and vision aids.

Papilledema Disturbances in vision, Corticosteroid, surgery or headache, vomiting, radiation therapy, weight increased brain pressure. loss and a diuretic, if infected can be treated by antibiotics.

Toxic Amblyopia Vision deteriorating, Avoid alcohol and other nutritional deficiency. drugs. If lead is the cause use chelating drugs, if ethylene glycol or methanol poisoning then hemodialysis and fomeziple. Cranial Nerve III: Oculomotor

Type of Nerve: Motor ​ Function of Nerve: Raise eyelids, move eyes, regulate the size of ​ pupils, focus of lenses.

Brief description: The Oculomotor cranial nerve is also known as the common ​ ocular motor nerve. It is the third of the 12 pairs of cranial nerves. It controls eye movement and is also responsible for pupil size and It originates in the midbrain.

Name Nerve Disorder Treatment

Oculomotor Nerve Palsy Diplopia and Ptosis, No treatment, usually misalignment of eyes. requires surgery.

Nystagmus Involuntary eye Eyeglasses and contact movement, reduced lenses, surgery can help. vision and depth Magnifying glasses and increased lightning can perceptions, affects arise improvement in balance and coordination. vision as well.

Strabismus Misaligned eyes, Optical, medical or Esotropia and exotropia, Surgical are required double vision. depending on age.

Cranial Nerve IV: Trochlear

Type of Nerve: Motor ​ Function of Nerve: Eye movements, proprioception ​

Brief description: The Trochlear nerve has a motor and somatic functions that ​ are connected to the superior oblique muscle of the eye, being able to make the eyeballs move and rotate. Its nucleus also originates in the mesencephalon as well as the oculomotor nerve and is the fourth of the 12 pairs of cranial nerves.

Unique aspects: ● Smallest number of axons. ● Greatest intracranial length. ● Only cranial nerve that exits from the dorsal aspect of the brainstem. ● Innervates a muscle on the opposite side of its origin.

Name Nerve Disorder Treatment

Trochlear Nerve Palsy Double images, limited Eye exercises, prism eye movement, computed glasses, usually resolves tomography. itself over time.

Cranial Nerve V: Trigeminal

Type of Nerve: Mixed ​ Function of Nerve: Sensations of the head and face, chewing ​ movements, and muscle sense.

Brief description: The Trigeminal is a mixed cranial nerve (sensitive, sensory ​ and motor), being the largest of all cranial nerves, it is the fifth of the 12 pairs of cranial nerves. Its function is to carry sensitive information to the face, to convey information for the chewing process. The sensory fibers convey sensations of touch, pain, and temperature from the front of the head including the mouth and also from the meninges.

Important side note: The anatomy of the Trigeminal nerve is used for portraying ​ ​ the Wallenberg Syndrome or Lateral Medullary Syndrome, in this syndrome a stroke ​ causes a loss of pain-temperature sensation from one side of the face and the other side of the body.

Name Nerve Disorder Treatment

Trigeminal Neuralgia Extreme pain triggers Acupuncture, from small things like biofeedback, chiropractic, eating or even feeling a and vitamin or nutritional breeze and smiling. therapy may work, surgery is recommended.

Cranial Nerve VI: Abducens

Type of Nerve: Motor ​ Function of Nerve: Produce movements of the eyes ​

Brief description: The abducens is also known as the external ocular motor ​ cranial nerve and it is the sixth of the 12 pairs of cranial nerves. It is a cranial motor pair, responsible for transmitting the motor stimuli to the external rectus muscle of the eye and therefore allowing the eye to move to the opposite side from where we have the nose.

Important side note: 15-40% of people with tuberculosis have some resulting ​ cranial nerve deficit, the Abducens nerve is the most commonly affected cranial nerve in immunocompetent people with tuberculosis.

Name Nerve Disorder Treatment

Sixth Nerve Palsy Double vision, vision Treatment is unnecessary impairment, poor eye and sixth nerve palsy alignment, strabismus. improves in time.

Cranial Nerve VIII: Facial or Intermediate

Type of Nerve: Mixed ​ Function of Nerve: Facial expressions, secretion of saliva, taste. ​

Brief description: This is another mixed cranial pair since it consists of several ​ nerve fibers that perform different functions, like ordering the muscles of the face to create facial expressions and also send signals to the salivary and lacrimal glands. On the other hand, it collects taste information through the tongue. It is the seventh of the 12 pairs of cranial nerves.

Name Nerve Disorder Treatment

Bell’s Palsy Pain behind their ear 1-2 eye patching and propr to noticing lubrication, lubricating weakness, sounds louder drops for the eye as well than normal, one side of as eye ointment should face paralyzed. be used at night.

Cranial Nerve VIII: Vestibulocochlear

Type of Nerve: Sensory ​ Function of Nerve: Balance or equilibrium sense. Hearing. ​

Brief description: It is a sensory cranial nerve. It is also known as the auditory ​ and vestibular nerve, thus forming vestibulocochlear. He is responsible for balance and orientation in space and auditory function. It is the eighth of the 12 pairs of cranial nerves.

Important side note: Name Nerve Disorder Treatment

Neurofibromatosis Type II Complete lost of Surgery of the removal hearing and loss of of the acoustic balance. neuroma.

Vestibular Neuronitis Dizziness and vertigo. Will treat itself over time, avoid becoming dehydrated.

Cranial Nerve IX: Glossopharyngeal

Type of Nerve: Mixed ​ Function of Nerve: Taste and other sensations of tongue, swallowing, ​ secretion of saliva, aid in reflex control of blood pressure and respiration.

Brief description: It is a nerve whose influence lies in the tongue and pharynx. It ​ collects information from the taste buds (tongue) and sensory information from the pharynx. It leads orders to the salivary gland and various neck muscles that help with swallowing. It also monitors blood pressure. It is the ninth of the 12 pairs of cranial nerves.

Important side note: Name Nerve Disorder Treatment

Glossopharyngeal Brief excruciating pain, Surgery mainly named neuralgia can be triggered from microvascular chewing, swallowing, decompression, taking talking, yawning, Anticonvulsants may coughing or sneezing. help. Pain can last several minutes.

Cranial Nerve X: Vagus

Type of Nerve: Mixed ​ Function of Nerve: Transmit impulses to muscles associated with ​ speech, swallowing, the heart, smooth muscles of visceral organs in the thorax, and abdomen.

Brief description: This nerve is also known as pneumogastric. It emerges from ​ the medulla oblongata and supplies nerves to the pharynx, esophagus, larynx, trachea, bronchi, heart, stomach and liver. Like the previous nerve, it influences the action of swallowing but also in sending and transmitting signals to our autonomous system, to help the regulate activation and control stress levels or send signals directly to our sympathetic system. It is the tenth of the 12 pairs of cranial nerves.

Name Nerve Disorder Treatment

Slow or no movement of Treatment of Gastroparesis food from the stomach to gastroparesis includes the small intestine. diet, medication, and

devices or procedures that facilitate emptying of the stomach.

Cranial Nerve XI: Accessory

Type of Nerve: Motor ​ Function of Nerve: Turning movements of the head, movements of the ​ shoulder and viscera, voice production

Brief description: This cranial pair is named the spinal nerve. It is a motor nerve ​ and could be understood as one of the most “pure”. It governs movements of the head and shoulders by supplying the sternocleidomastoid and trapezius muscles in the (anterior and posterior) regions of the neck. The spinal nerve also allows us to throw our heads back. Thus, we would say that it intervenes in the movements of the head and the shoulders. It is the eleventh of the 12 pairs of cranial nerves.

Name Nerve Disorder Treatment

Accessory Nerve Disorder Partial paralysis, Intraoperative asymmetric neckline, procedures, postoperative drooping shoulder. procedures or an Eden-Lange procedure.

Cranial Nerve XII: Hypoglossal

Type of Nerve: Motor ​ Function of Nerve: Tongue movements ​

Brief description: And last but not least the Hypoglossal cranial nerve, this is a ​ motor nerve which, like the vagus and glossopharyngeal, is involved in tongue muscles, swallowing and speech. It is the final and twelfth of the 12 pairs of cranial nerves.

Name Nerve Disorder Treatment

Hypoglossal Nerve Tongue becomes weak, Treatment depends on Disorder atrophies. Difficulty the cause at hand as their speaking, Chewing and can be a few reasons. Swallowing. Subtle twitches.

Sources ● https://blog.cognifit.com ● https://www.yale.edu ● http://www.nytimes.com ● http://www.ivyroses.com ● https://www.verywell.com ● https://www.google.ie/imghp ● http://www.tandurust.com ​ ● https://www.nhs.uk ● http://www.merckmanuals.com ● http://www.umkelloggeye.org ● https://www.aoa.org ● https://www.mayoclinic.org