You do not have permission to edit this page, for the following reasons:

This IP address has been blocked from editing Wikipedia.
This does not affect your ability to read Wikipedia pages.
Most people who see this message have done nothing wrong. Some kinds of blocks restrict editing from specific service providers or telecom companies in response to recent abuse or vandalism, and can sometimes affect other users who are unrelated to that abuse. Review the information below for assistance if you do not believe that you have done anything wrong.

The IP address or range 35.171.0.0/16 has been blocked (disabled) by ‪JJMC89‬ for the following reason(s):

The IP address that you are currently using has been blocked because it is believed to be a web host provider or colocation provider. To prevent abuse, web hosts and colocation providers may be blocked from editing Wikipedia.
You will not be able to edit Wikipedia using a web host or colocation provider because it hides your IP address, much like a proxy or VPN.
We recommend that you attempt to use another connection to edit. For example, if you use a proxy or VPN to connect to the internet, turn it off when editing Wikipedia. If you edit using a mobile connection, try using a Wi-Fi connection, and vice versa. If you are using a corporate internet connection, switch to a different Wi-Fi network. If you have a Wikipedia account, please log in.
If you do not have any other way to edit Wikipedia, you will need to request an IP block exemption.

How to appeal if you are confident that your connection does not use a colocation provider's IP address:
If you are confident that you are not using a web host, you may appeal this block by adding the following text on your talk page: ((unblock|reason=Caught by a colocation web host block but this host or IP is not a web host. My IP address is _______. Place any further information here. ~~~~)). You must fill in the blank with your IP address for this block to be investigated. Your IP address can be determined here. Alternatively, if you wish to keep your IP address private you can use the unblock ticket request system. There are several reasons you might be editing using the IP address of a web host or colocation provider (such as if you are using VPN software or a business network); please use this method of appeal only if you think your IP address is in fact not a web host or colocation provider.

Administrators: The IP block exemption user right should only be applied to allow users to edit using web host in exceptional circumstances, and requests should usually be directed to the functionaries team via email. If you intend to give the IPBE user right, a CheckUser needs to take a look at the account. This can be requested most easily at SPI Quick Checkuser Requests. Unblocking an IP or IP range with this template is highly discouraged without at least contacting the blocking administrator.

This block will expire on 05:20, 2 December 2024.

Even when blocked, you will usually still be able to edit your user talk page, as well as email administrators and other editors.

For information on how to proceed, please read the FAQ for blocked users and the guideline on block appeals. The guide to appealing blocks may also be helpful.

Other useful links: Blocking policy · Help:I have been blocked
Your IP address is in a range that has been blocked on all Wikimedia Foundation wikis. The block was made by ‪Jon Kolbert‬. The reason given is Open proxy/Webhost: See the help page if you are affected .
- Start of block: 05:38, 21 February 2024
- Expiry of block: 05:38, 21 February 2029
Your current IP address is 35.171.25.239. The blocked range is 35.171.0.0/16. Please include all above details in any queries you make. If you believe you were blocked by mistake, you can find additional information and instructions in the No open proxies global policy. Otherwise, to discuss the block please post a request for review on Meta-Wiki. You could also send an email to the stewards VRT queue at stewards@wikimedia.org including all above details.

You can view and copy the source of this page:

((Short description|Type of neurological examination))
((multiple issues|
((primary sources|date=January 2014))
((Howto|date=January 2014))
))
((Infobox diagnostic
| name = Cranial nerve examination
| image = Eye_dilate.gif
| alt = Eye dilation
| caption = One component of the examination (III) uses the [[pupillary light reflex]] to assess the status of the [[oculomotor nerve]] (CNIII).
| pronounce =
| purpose = part of the neurological examination
| test of =
| based on =
| synonyms =
| reference_range =
| calculator =
| DiseasesDB = <!--((DiseasesDB2|numeric_id))-->
| ICD10 = <!--((ICD10|Group|Major|minor|LinkGroup|LinkMajor)) or ((ICD10PCS|code|char1/char2/char3/char4))-->
| ICD9 =
| ICDO =
| MedlinePlus = <!--article_number-->
| eMedicine = <!--article_number-->
| MeshID =
| OPS301 = <!--((OPS301|code))-->
| LOINC = <!--((LOINC|code))-->
))
The '''cranial nerve exam''' is a type of [[neurological examination]]. It is used to identify problems with the [[cranial nerves]] by [[physical examination]]. It has nine components. Each test is designed to assess the status of one or more of the twelve cranial nerves (I-XII). These components correspond to testing the sense of smell (I), visual fields and acuity (II), eye movements (III, IV, VI) and pupils (III, sympathetic and parasympathetic), sensory function of face (V), strength of facial (VII) and shoulder girdle muscles (XI), hearing and balance (VII, VIII), taste (VII, IX, X), pharyngeal movement and reflex (IX, X), tongue movements (XII).

==Components==

===CN I===
The first test is for the [[olfactory nerve]]. [[Olfaction|Smell]] is tested in each [[nostril]] separately by placing stimuli under one nostril and occluding the opposing nostril. The stimuli used should be non-irritating and identifiable. Some example stimuli include [[cinnamon]], [[cloves]], and [[toothpaste]]. Loss of the sense of smell is called anosmia and can be either unilateral or bilateral. Bilateral loss can occur with [[rhinitis]], [[smoking]], or [[aging]]. Unilateral loss indicates a possible nerve lesion or deviated septum. This test is usually skipped on a cranial nerve exam.<ref name="BrillmanKahan2005">((cite book|author1=Jon Brillman|author2=Scott Kahan|title=In A Page Neurology|url=https://books.google.com/books?id=fSlFA8B24FgC&pg=PA4|access-date=27 June 2011|date=1 March 2005|publisher=Lippincott Williams & Wilkins|isbn=978-1-4051-0432-6|pages=4–))</ref>

The short axons of the first cranial nerve regenerate on a regular basis. The neurons in the olfactory epithelium have a limited life span, and new cells grow to replace the ones that die off. The axons from these neurons grow back into the CNS by following the existing axons—representing one of the few examples of such growth in the mature nervous system. If all of the fibers are sheared when the brain moves within the cranium, such as in a motor vehicle accident, then no axons can find their way back to the olfactory bulb to re-establish connections. If the nerve is not completely severed, the anosmia may be temporary as new neurons can eventually reconnect.<ref name="Neuroscience University of Toronto">((CC-notice|cc=by4|url=http://neuroscience.openetext.utoronto.ca/chapter/anatomy-physiology-the-neurological-exam/)) ((cite book|last1=Ju|first1=William|title=Neuroscience|location=Toronto|publisher=University of Toronto|date= November 11, 2023|at=1.6 The Neurological Exam))</ref>

===CN II===
Vision via the [[optic nerve]] is examined both in fields of vision, and in clarity of vision.
* [[Visual fields]] are assessed by asking the patient to cover one eye while the examiner tests the opposite eye. The examiner wiggles the finger in each of the four quadrants and asks the patient to state when the finger is seen in the [[peripheral vision|periphery]]. The examiner's visual fields should be normal, since it is used as the baseline. The optic nerves from both sides enter the cranium through the respective optic canals and meet at the optic chiasm at which fibers sort such that the two halves of the visual field are processed by the opposite sides of the brain. Deficits in visual field perception often suggest damage along the length of the [[optic pathway]] between the orbit and the [[diencephalon]]. For example, loss of peripheral vision may be the result of a pituitary tumor pressing on the [[optic chiasm]]. The pituitary, seated in the [[sella turcica]] of the [[sphenoid bone]], is directly inferior to the optic chiasm. The axons that decussate in the chiasm are from the medial retinae of either eye, and therefore carry information from the peripheral visual field.<ref name="Neuroscience University of Toronto"/>

* [[Visual acuity]] is tested in each [[human eye|eye]] separately. Ensure the patient's vision is corrected with [[eyeglasses]] or a pinhole. The patient is asked to read progressively smaller lines on the '''near card''' or ''[[Snellen chart]]''. The Snellen Chart demonstrates visual acuity by presenting standard Roman letters in a variety of sizes. The result of this test is a rough generalization of the acuity of a person based on the normal accepted acuity, such that a letter that subtends a visual angle of 5 minutes of an arc at 20 feet can be seen. To have 20/60 vision, for example, means that the smallest letters that a person can see at a 20-foot distance could be seen by a person with normal acuity from 60 feet away. Testing the extent of the visual field means that the examiner can establish the boundaries of peripheral vision as simply as holding their hands out to either side and asking the patient when the fingers are no longer visible without moving the eyes to track them. If it is necessary, further tests can establish the perceptions in the visual fields. Physical inspection of the optic disk, or where the optic nerve emerges from the eye, can be accomplished by looking through the pupil with an [[ophthalmoscope]].<ref name="Neuroscience University of Toronto"/>

===CN III, CN IV, CN VI===

The three nerves that control the [[extraocular muscles]] are the [[oculomotor nerve]] (CN III), the [[trochlear nerve]] (CN IV), and the [[abducens nerve]] (CN VI). As the name suggests, the abducens nerve is responsible for abducting the eye, which it controls through contraction of the [[lateral rectus muscle]]. The trochlear nerve controls the [[superior oblique muscle]] to rotate the eye along its axis in the orbit medially, which is called [[intorsion]], and is a component of focusing the eyes on an object close to the face. The oculomotor nerve controls all the other extraocular muscles, as well as a muscle of the upper eyelid. Movements of the two eyes need to be coordinated to locate and track visual stimuli accurately. When moving the eyes to locate an object in the horizontal plane, or to track movement horizontally in the visual field, the lateral rectus muscle of one eye and medial rectus muscle of the other eye are both active. The [[lateral rectus]] is controlled by neurons of the [[abducens nucleus]] in the superior medulla, whereas the medial rectus is controlled by neurons in the [[oculomotor nucleus]] of the midbrain.<ref name="Neuroscience University of Toronto"/>

* [[Eye movements]] are tested by standing one meter in front of the patient and asking the patient to follow a target with eyes only, and not the head. The target is moved in an "H" shape and the patient is asked to report any [[diplopia]]. Then, the target is held at the lateral ends of the patient's visual field. Nystagmus is tested for. One or two beats is a normal finding. The [[accommodation reflex]] is tested by moving the target towards the patient's nose. As the eyes converge, the pupils should constrict. The '''optokinetic nystagmus''' test is optional and involves asking the patient to look at a strip of vertical lines moving horizontally across visual field. Nystagmus is normally observed.

* [[Extraocular muscles|Extraocular movements]] are tested by '''inspecting''' for [[ptosis (eyelid)|ptosis]], eye position and [[physiologic nystagmus|nystagmus]]. The pupil size is measured, its shape and any asymmetry is tested. A commonly used abbreviation to describe normal pupils is [[PERRLA]] (pupils equal, round and reactive to light and accommodation).

* [[Pupillary light reflex]] is tested by having the patient stare into the distance as the examiner shines the [[penlight]] obliquely into each [[pupil]]. Pupillary constriction is tested for on the eye examined (direct response) and on the opposite eye (consensual response). The [[swinging flashlight test]] involves moving the light between the two pupils. Normally both direct and consensual responses are elicited when the light shines on an eye, and some [[pupil dilation|dilation]] will occur during the swing between.

===CN V===
Testing the [[trigeminal nerve]] involves testing its three branches. 
* '''Light touch''' is tested in each of the three divisions of the trigeminal nerve and on each side of the face using a cotton wisp or tissue paper. The ophthalmic division is tested by touching the forehead, the maxillary division is tested by touching the cheeks, and the mandibular division is tested by touching the chin. Be careful not to test the mandibular division too laterally, as the mandible is innervated by the [[great auricular nerve]] (C2 and C3). A common mistake is to use a stroking motion, which will trigger pain and temperature nerves. Instead, a point stimulus should be applied. For '''pain and temperature''' repeat the same steps as light touch but use a sharp object and a cold tuning fork respectively.

* [[Corneal reflex]] is conducted along with the [[facial nerve]] section of the test. Note the sensory innervation of the cornea is provided by the [[trigeminal nerve]] while the motor innervation for blinking the eye is provided by the [[facial nerve]].-

* [[Muscles of mastication]] ([[temporalis]], [[masseter]]) should be inspected for atrophy. Palpate the temporalis and masseter as the patient clenches the jaw. The pterygoids can be tested by asking the patient to keep the mouth open against resistance, and move from side to side against resistance. A [[jaw jerk reflex]] can be tested by placing a finger over the patient's chin and then tapping the finger with a reflex hammer. Normally the jaw moves minimally.

===CN VII===
The [[facial nerve]] is tested by 
inspecting for facial asymmetry and involuntary movements. The individual is asked to:
# Raise both eyebrows
# Frown
# Close both eyes tightly so that you can not open them. Test muscular strength by trying to open them
# Show both upper and lower teeth
# Smile
# Puff out both cheeks

The sensory component is tested for taste. Testing this is as simple as introducing salty, sour, bitter, or sweet stimuli to either side of the tongue. The patient should respond to the taste stimulus before retracting the tongue into the mouth. Stimuli applied to specific locations on the tongue will dissolve into the saliva and may stimulate taste buds connected to either the left or right of the nerves, masking any lateral deficits.<ref name="Neuroscience University of Toronto"/> 

===CN VIII===
The [[vestibulocochlear nerve]] is tested for hearing and balance.
* '''Hearing''' is tested by whispering numbers in one ear as patient covers the other and ask the patient to repeat the numbers. Alternatively, have patient close their eyes and say "left" or "right" depending on the side from which they hear the sound. Vigorously rub fingers together in one ear at a time to produce rustling sound.<ref>((Cite web|url = https://www.eyecancer.com/conditions/3/choroidal-melanoma|title = Examination of the Cranial Nerves| date=22 April 2016 ))</ref> 

More sensitive hearing tests are [[Rinne test]] and [[Weber test]]. The Rinne test involves using a tuning fork to distinguish between conductive hearing and sensorineural hearing. Conductive hearing relies on vibrations being conducted through the ossicles of the middle ear. Sensorineural hearing is the transmission of sound stimuli through the neural components of the inner ear and cranial nerve. A vibrating [[tuning fork]] is placed on the [[mastoid process]] and the patient indicates when the sound produced from this is no longer present. Then the fork is immediately moved to just next to the ear canal so the sound travels through the air. If the sound is not heard through the ear, meaning the sound is conducted better through the temporal bone than through the ossicles, a conductive hearing deficit is present.<ref name="Neuroscience University of Toronto"/>

The Weber test also uses a tuning fork to differentiate between conductive versus sensorineural hearing loss. In this test, the tuning fork is placed at the top of the skull, and the sound of the tuning fork reaches both inner ears by travelling through bone. In a healthy patient, the sound would appear equally loud in both ears. With unilateral conductive hearing loss, however, the tuning fork sounds louder in the ear with hearing loss. This is because the sound of the tuning fork has to compete with background noise coming from the outer ear, but in conductive hearing loss, the background noise is blocked in the damaged ear, allowing the tuning fork to sound relatively louder in that ear. With unilateral sensorineural hearing loss, however, damage to the cochlea or associated nervous tissue means that the tuning fork sounds quieter in that ear.<ref name="Neuroscience University of Toronto"/>

* Vestibular Function

===CN IX, CN X===
The [[glossopharyngeal nerve]] (CN IX) and [[vagus nerve]] (CN X) are tested for:
* Gag response
* Visualizing uvula deviation away from affected side on articulating "AHH" with tongue depressor.
* Palatal articulation "KA"
* Guttural articulation "GO"

===CN XI===
The [[accessory nerve]] is tested for:
* Shrug shoulders ([[trapezius muscle]])
* Turn head from side to side ([[sternocleidomastoid muscle]])

===CN XII===
The [[hypoglossal nerve]] has a sole motor function for most of the muscles of the tongue:
* Stick out tongue and move it to one side, then the other<ref>((Cite web|url = http://informatics.med.nyu.edu/modules/pub/neurosurgery/cranials.html|title = Examination of the Cranial Nerves|access-date = 2014-06-26|archive-date = 2021-03-09|archive-url = https://web.archive.org/web/20210309153515/https://informatics.med.nyu.edu/modules/pub/neurosurgery/cranials.html|url-status = dead))</ref>
* Inspect for tongue atrophy, fasciculations or asymmetry in movement or appearance.

==See also==
* [[Cranial nerves]]
* [[Cranial nerve nucleus]]

==References==
((reflist))

==External links==
* [http://www.NeurologyExam.com NeurologyExam.com] Free neurology exam videos by Cleveland Clinic trained neurologist.

((Medical records and physical exam))

[[Category:Neurology procedures]]
[[Category:Physical examination]]

Pages transcluded onto the current version of this page (help):

Cranial nerve examination (edit)
Template:Ambox (view source) (template editor protected)
Template:CC-notice (view source) (semi-protected)
Template:Cite book (view source) (protected)
Template:Cite web (view source) (protected)
Template:Creative Commons text attribution notice (view source) (semi-protected)
Template:Find sources mainspace (view source) (template editor protected)
Template:Hlist/styles.css (view source) (protected)
Template:How-to (view source) (semi-protected)
Template:Howto (view source) (semi-protected)
Template:Infobox (view source) (template editor protected)
Template:Infobox diagnostic (view source) (semi-protected)
Template:Main other (view source) (protected)
Template:Medical records and physical exam (edit)
Template:Multiple issues (view source) (template editor protected)
Template:Multiple issues/styles.css (view source) (template editor protected)
Template:Navbox (view source) (template editor protected)
Template:Pagetype (view source) (protected)
Template:Primary sources (view source) (template editor protected)
Template:Reflist (view source) (protected)
Template:Reflist/styles.css (view source) (protected)
Template:SDcat (view source) (protected)
Template:Short description (view source) (protected)
Template:Short description/lowercasecheck (view source) (protected)
Template:Template other (view source) (protected)
Module:Arguments (view source) (protected)
Module:Category handler (view source) (protected)
Module:Category handler/blacklist (view source) (protected)
Module:Category handler/config (view source) (protected)
Module:Category handler/data (view source) (protected)
Module:Category handler/shared (view source) (protected)
Module:Check for unknown parameters (view source) (protected)
Module:Citation/CS1 (view source) (protected)
Module:Citation/CS1/COinS (view source) (protected)
Module:Citation/CS1/Configuration (view source) (protected)
Module:Citation/CS1/Date validation (view source) (protected)
Module:Citation/CS1/Identifiers (view source) (protected)
Module:Citation/CS1/Utilities (view source) (protected)
Module:Citation/CS1/Whitelist (view source) (protected)
Module:Citation/CS1/styles.css (view source) (protected)
Module:Disambiguation/templates (view source) (protected)
Module:Find sources (view source) (template editor protected)
Module:Find sources/config (view source) (template editor protected)
Module:Find sources/links (view source) (template editor protected)
Module:Find sources/templates/Find sources mainspace (view source) (template editor protected)
Module:Infobox (view source) (template editor protected)
Module:Infobox/styles.css (view source) (template editor protected)
Module:InfoboxImage (view source) (template editor protected)
Module:Message box (view source) (protected)
Module:Message box/ambox.css (view source) (protected)
Module:Message box/configuration (view source) (protected)
Module:Namespace detect/config (view source) (protected)
Module:Namespace detect/data (view source) (protected)
Module:Navbar (view source) (protected)
Module:Navbar/configuration (view source) (protected)
Module:Navbar/styles.css (view source) (protected)
Module:Navbox (view source) (template editor protected)
Module:Navbox/configuration (view source) (template editor protected)
Module:Navbox/styles.css (view source) (template editor protected)
Module:Pagetype (view source) (protected)
Module:Pagetype/config (view source) (protected)
Module:Pagetype/disambiguation (view source) (protected)
Module:Pagetype/setindex (view source) (protected)
Module:Pagetype/softredirect (view source) (protected)
Module:SDcat (view source) (protected)
Module:String (view source) (protected)
Module:Unsubst (view source) (protected)
Module:Wikitext Parsing (view source) (protected)
Module:Yesno (view source) (protected)

Return to Cranial nerve examination.

Retrieved from "https://en.wikipedia.org/wiki/Cranial_nerve_examination"