Optic nerve
The optic nerve, also known as cranial nerve II, or simply as CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral genicula…
Snellen chart
A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen, who developed the chart in 1862. Many ophthalmologists and vision scientists now use an improved chart known as the LogMAR chart.
How do you assess cranial nerve 2?
- Have patient stand 20 feet from chart
- First the patient will cover the right eye, then left eye, and lastly read the chart with both eyes.
- Covering the right eye first, have the patient recite the lowest line they can read with ease.
- Repeat this with the left eye and then both eyes.
How to assess the cranial nerves?
- Pupils should be round and bilaterally equal in size. The diameter of the pupils usually ranges from two to five millimeters. ...
- Test pupillary reaction to light. ...
- Test eye convergence and accommodation. ...
- The acronym PERRLA is commonly used in medical documentation and refers to, “pupils are equal, round and reactive to light and accommodation.”
What are the 12 cranial nerve tests?
Nystagmus secondary to BPPV has the following nearly pathognomic characteristics:
- A latency period of 5 to 10 sec
- Usually, vertical (upward-beating) nystagmus when the eyes are turned away from the affected ear and rotary nystagmus when the eyes are turned toward the affected ear
- Nystagmus that fatigues when the Dix-Hallpike maneuver is repeated
How to conduct a cranial nerve examination?
• Ask patient to turn head to one side and push against examiners hand or ask to flex head against resistance, palpate and evaluate strength of sternocleidomastoid muscle. • Evaluate both right and left side, compare for symmetry. CRANIAL NERVES 39 40.
What is the function of cranial nerve 2?
The optic nerve is the second cranial nerve (CN II) responsible for transmitting visual information.
How do you assess cranial nerve function?
Assessment and findings: Assess this cranial nerve by asking the patient to say “ah.” Watch for vocal clarity, uvula alignment, and symmetric posterior mouth movement. Gently touching both sides of the back of the throat with a tongue blade should elicit a gag response.
What is cranial nerve II visual acuity test?
Test interpretation This is essentially a test of macular vision. The numbers of the lines indicate the distance that a normally- sighted person would be able to see it. Visual acuity is expressed as the distance the letters are read/the distance at which they should be read.
Is cranial nerve 2 sensory or motor?
sensory nervesCranial nerves I, II, and VIII are pure sensory nerves. Cranial nerves III, IV, VI, XI, and XII are pure motor nerves. Cranial nerves V, VII, IX, and X are mixed sensory and motor nerves.
How do you assess cranial nerve 3?
Inability to follow and object in direction of CN III (the quickest test is to observe upward gaze which is all CN III; the eye on the affected side does not look upward) Inability to open the eyelid. CN III dysfunction causes the eyelid on the affected side to become "droopy".
Why do nurses assess cranial nerves?
Assessment of the cranial nerves provides insightful and vital information about the patient's nervous system.
How do you test visual acuity?
You will be asked to cover one eye with the palm of your hand, a piece of paper, or a small paddle while you read out loud the smallest line of letters you can see on the chart. Numbers, lines, or pictures are used for people who cannot read, especially children. If you are not sure of the letter, you may guess.
How do you test visual accommodation?
Testing for the accommodation reflex follows nicely on from eye movements. Ask the patient to keep focusing on the tip of your index finger and slowly move it towards them, aiming for the tip of their nose. You need to be watching their pupils to make sure you see them constrict as your finger gets closer.
How do you assess cranial nerve XII?
The 12th CN is tested by having the patient stick out their tongue and move it side to side. Further strength testing can be done by having the patient push the tongue against a tongue blade. Inspect the tongue for atrophy and fasciculations.
How do you remember the cranial nerves sensory or motor?
Cranial nerve mnemonics to remember the names of the nerves in order include: On old Olympus's towering top, a Finn and German viewed some hops. Ooh, ooh, ooh to touch and feel very good velvet....To remember cranial nerve functions, the words in the mnemonic start with:S for sensory.M for motor.B for both.
Which nerve controls tongue movements?
The hypoglossal nerveThe hypoglossal nerve enables tongue movement. It controls the hyoglossus, intrinsic, genioglossus and styloglossus muscles. These muscles help you speak, swallow and move substances around in your mouth.
How do you test vagus nerve?
To test the vagus nerve, a doctor may check the gag reflex . During this part of the examination, the doctor may use a soft cotton swab to tickle the back of the throat on both sides. This should cause the person to gag.
Which cranial nerves are evaluated together?
The 9th (glossopharyngeal) and 10th (vagus) cranial nerves are usually evaluated together. Whether the palate elevates symmetrically when the patient says "ah" is noted. If one side is paretic, the uvula is lifted away from the paretic side.
What is the 2nd cranial nerve?
For the 2nd (optic) cranial nerve, visual acuity is tested using a Snellen chart for distance vision or a handheld chart for near vision; each eye is assessed individually , with the other eye covered.
What is the slow component of vestibular nystagmus?
Vestibular nystagmus has 2 components: A slow component caused by vestibular input. A quick, corrective component that causes movement in the opposite direction (called beating) The direction of the nystagmus is defined by the direction of the quick component because it is easier to see.
What nerve is evaluated by asking the patient to extend the tongue and inspecting it for atrophy, fasciculations,
The 12th (hypoglossal) cranial nerve is evaluated by asking the patient to extend the tongue and inspecting it for atrophy, fasciculations, and weakness (deviation is toward the side of a lesion).
What is the function of the 1st cranial nerve?
Smell, a function of the 1st (olfactory) cranial nerve, is usually evaluated only after head trauma or when lesions of the anterior fossa (eg, meningioma) are suspected or patients report abnormal smell or taste.
How to test for taste in the anterior two thirds of the tongue?
Taste in the anterior two thirds of the tongue can be tested with sweet, sour, salty, and bitter solutions applied with a cotton swab first on one side of the tongue, then on the other. Hyperacusis, indicating weakness of the stapedius muscle, may be detected with a vibrating tuning fork held next to the ear.
Is nystagmus peripheral or central?
If nystagmus is absent with visual fixation but present with Frenzel lenses, it is probably peripheral. If nystagmus changes direction (eg, from one side to the other when, for example, when the direction of gaze changes), it is probably central. However, absence of this finding does not exclude central causes.
How many cranial nerves are there in the nervous system?
Assessment of the cranial nerves provides insightful and vital information about the patient’s nervous system. There are 12 cranial nerves that are often forgotten by nurses, so with that in mind, here’s a free assessment form that you can use!
How to test light sensation?
(same as above) (same as above) To test deep sensation, use alternating blunt and sharp ends of an object. Determine sensation to warm and cold object by asking client to identify warmth and coldness. (same as above)
What reflex should a client have to respond to light and deep sensation?
While the client looks upward, lightly touch the lateral sclera of eye to elicit blink reflex. Client should have a (+) corneal reflex, able to respond to light and deep sensation and able to differentiate hot from cold. Client was able to elicit corneal reflex, sensitive to pain stimuli and distinguish hot from cold.
How to test cranial nerves II and III?
The pupillary light reflex tests both cranial nerves II and III. First, inspect both pupils and make sure they are equal in size and shape. Then dim the lights if possible and shine a penlight directly into the right eye. Both pupils should constrict and maintain symmetry. Note if they are brisk or sluggish and if they are symmetric. Remove the light source and watch both eyes dilate equally as well. Do the same for the left eye.
Why is cranial nerve assessment important?
The cranial nerve assessment is an important part of the neurologic exam, as cranial nerves can often correlate with serious neurologic pathology. This is important for nurses, nurse practitioners, and other medical professionals to know how to test cranial nerves and what cranial nerve assessment abnormalities may indicate.
What nerve controls the eyeball?
The fourth cranial nerve, the trochlear nerve, innervates the superior oblique muscle of the eyes. This means it controls the downward movement of the eyeball and prevents it from rolling upward. When there is a fourth nerve palsy, patients will often complain of vertical diplopia and/or tilting of objects.
What nerve controls the movement of the eyelid?
The oculomotor nerve controls the majority of the extraocular muscles. It is primarily responsible for eye movement, eyelid movement, and pupillary constriction. If there is any oculomotor nerve impairment, there will be a pupillary dilation, ptosis ( drooping eyelid ), and outward deviation of the eye – termed abduction. When a patient has diplopia (double vision), it is often due to a unilateral lesion on this cranial nerve. In most cases, third nerve palsy resolves over weeks to months.
What nerves are tested for oculomotor nerves?
To test the oculomotor nerve, you need to assess the EOMs. Testing the EOMs also tests cranial nerves IV and VI, as all three nerves are responsible for eye movement.
What nerve is responsible for the sense of smell?
The olfactory nerve is responsible for the sense of smell. Although rarely tested in practice, alterations in smell can be caused by serious intracranial pathology (brain tumors, strokes, TBI), neurodegenerative diseases like Alzheimer’s, Parkinson’s, or MS, or benign and transient causes such as the common cold.
How to test hypoglossal nerve?
How to test the Hypoglossal Nerve. To test the hypoglossal nerve, ask the patient to stick out their tongue. If the tongue deviates to one side , this indicates hypoglossal nerve dysfunction on the side of deviation. Then ask them to move their tongue from side to side rapidly.
Why wouldn't cranial nerves work?
Why wouldn’t a cranial nerve “work ”? In many neuro diseases, the neurons that supply a particular nerve is damaged, which makes the nerve not function properly. For example, in multiple sclerosis the myelin sheath of the neurons in the central nervous system are damaged, which leads to some sensory and motor problems.
What nerve causes blurry vision?
Therefore, you can assess this nerve (cranial nerve II) for any type of abnormalities.
Which nerve is responsible for mastication?
Cranial Nerve V. To test Cranial Nerve V…..trigeminal nerve: This nerve is responsible for many functions and mastication is one of them. Have the patient bite down and feel the masseter muscle and temporal muscle. Then have the patient try to open the mouth against resistance.
How far can a patient see with normal vision?
This means the patient can see at 20 feet what a person with normal vision can see at 30 feet.
Which nerve is involved in the afferent branch of the corneal reflex?
The afferent branch of the corneal reflex involves V1 of the trigeminal nerve whereas the efferent branch is mediated by the temporal and zygomatic branches of the facial nerve. To assess the corneal reflex: 1. Clearly explain what the procedure will involve to the patient and gain consent to proceed. 2.
How to test bone conduction?
1. Place a vibrating 512 Hz tuning fork firmly on the mastoid process ( apply pressure to the opposite side of the head to make sure the contact is firm). This tests bone conduction.
How many efferent limbs are there in the pupillary reflex?
Each afferent limb of the pupillary reflex has two efferent limbs, one ipsilateral and one contralateral. The afferent limb functions as follows: Sensory input (e.g. light being shone into the eye) is transmitted from the retina, along the optic nerve to the ipsilateral pretectal nucleus in the midbrain.
Which nerve is responsible for the transmission of taste?
The facial nerve (CN VII) transmits motor information to the muscles of facial expression and the stapedius muscle (involved in the regulation of hearing). The facial nerve also has a sensory component responsible for the conveyance of taste from the anterior two-thirds of the tongue.
Which nerve transmits sensory information about odours to the central nervous system?
The olfactory nerve (CN I) transmits sensory information about odours to the central nervous system where they are perceived as smell (olfaction). There is no motor component to the olfactory nerve.
Can oculomotor nerve palsy cause ptosis?
Oculomotor nerve palsy can also cause ptosis (due to a loss of innervation to levator palpebrae superioris) as well as mydriasis due to the loss of parasympathetic fibres responsible for innervating to the sphincter pupillae muscle.
Use Mnemonics to Aid Remembering and Identifying Abnormal findings.
- Takeaways 1. Many nurses find remembering the cranial nerves and their functions to be challenging. 2. Neurologic assessments occur in all healthcare settings. 3. Understanding normal and abnormal cranial nerve assessments can aid early diagnosis and treatment. Acute and chronic neurologic presentations exist in all healthcare settings. Abnormal fi...
Cranial Nerves
- The 12 pairs of cranial nerves are referred to by Roman numerals (CN I through XII) or by name. The cranial nerves control most of the sensory and motor function in the head and neck in addition to peripheral nerves that exit from the midbrain or the brainstem. Each cranial nerve has either a sensory, motor, or a combined function. Cranial nerve assessments help you determine …
Mnemonics
- Several mnemonics have been created to help nurses remember the name and function of the 12 cranial nerves. However, the most important component of a cranial nerve assessment is knowing normal vs. abnormal. Other creative tools for aiding cranial nerve recall include a University of Texas Southwestern Neurology YouTube video and a visual developed by Bolek. Remembering a…
Prevent Complications
- Cranial nerves control essential sensory and motor functions, including protective reflexes. Understanding these functions can help you identify abnormalities and intervene to prevent potential complications. Melissa Moreda is a diabetes clinical nurse specialist at the Duke Health System in Raleigh, North Carolina. Michelle Hill is the comprehensive stroke program coordinato…
References
- Bader MK, Littlejohns LR, Olson DM, eds. AANN Core Curriculum for Neuroscience Nursing. 6th ed. Chicago, IL: American Association of Neuroscience Nurses; 2016. Bolek B. Facing cranial nerve assessment. Am Nurse Today. 2006;1(2):21-2. Hickey JV. Comprehensive neurological examination. In Hickey JV, ed. The Clinical Practice of Neurological and Neurosurgical Nursing. …