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Function: Carries smell impulses from nasal mucous membrane to brainTest: For all assessments of the cranial nerves, have client sit in a comfortable position at your eye level. Ask the client to clear the nose to remove any mucus then to close eyes, occlude one nostril, and identify a scented object that you are holding such as soap, coffee, or vanilla. Repeat procedure for the other nostril.Normal Result: Client correctly identifies scent presented to each nostril.
Abnormal Result: Inability to smell (neurogenic anosmia) or identify the correct scent may indicate olfactory tract lesion or tumor or lesion of the frontal lobe. Loss of smell may also be congenital or due to other causes such as nasal disease, smoking, and use of cocaine.Tip: Some older clients' sense of smell may be decreased. |
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| CN II (optic) Sensory Function: Carries visual impulses from eye to brain Test 1: Use a Snellen chart to assess vision in each eyeNormal Result: Client has 20/20 vision OD (right eye) and OS (left eye).Abnormal Result: Abnormal findings include difficulty reading Snellen chart; missing letters, and squinting. |
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| Test 2: Ask the client to read a newspaper or magazine paragraph to assess near vision.Normal Result: Client reads print at 14 inches without difficulty.Abnormal Result: Client reads print by holding closer than 14 inches or holds print farther away as in presbyopia, which occurs with aging. |
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| Test 3: Assess visual fields of each eye by confrontation.Ø To perform the confrontation test, position yourself approx. 2 feet away from the client at eye levelØ Have the client cover his left eye while you cover your right eyeØ Look directly at each other with your uncovered eyesØ Next fully extend your left arm at midline and slowly move one finger (or a pencil) upward from below until the client sees your finger (or pencil)Ø Test the remaining three visual fields of the client's right eye (i.e., superior, temporal, and nasal). Repeat the test for the opposite eye.Normal Result: Full visual fieldsAbnormal Result: Loss of visual fields may be seen in retinal damage or detachment, with lesions of the optic nerve, or with lesions of the parietal cortex |
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| Test 4: Use an ophthalmoscope to view the retina and optic disc of each eye.Normal Result: Round red reflex is present, optic disc is 1.5 mm, round or slightly oval, well-defined margins, creamy pink with paler physiologic cup. Retina is pinkAbnormal Result: Papilledema (swelling of the optic nerve) results in blurred optic disc margins and dilated, pulsating veins. Papilledema occurs with increased intracranial pressure from intracranial hemorrhage or a brain tumor. Optic atrophy occurs with brain tumors |
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| CN III (oculomotor) CN IV (trochlear) CN VI (abducens) |
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| Function: Controls the extraocular eye movementsTest 1: Inspect margins of the eyelids of each eye.Normal Result: Eyelid covers about 2 mm of the iris.Abnormal Result: Ptosis (drooping of the eyelid) is seen with weak eye muscles such as in myasthenia gravis. |
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| CN III (oculomotor) CN IV (trochlear) CN VI (abducens) |
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Test 2: Assess extraocular movements using 6 Cardinal Positions. If nystagmus is noted, determine the direction of the fast and slow phases of movementØ Instruct the client to focus on an object you are holding (approx. 12 inches from the client's face). Ø From midline, client follows penlight or object with eyes, not moving head at all, in all directions.Ø Move the object through the six cardinal positions of gaze in a clockwise direction, and observe the client's eye movementsNormal Result: Eyes move in a smooth, coordinated motion in all directions (the six cardinal fields).Abnormal Result: Some abnormal eye movements and possible causes follow: Nystagmus: rhythmic oscillation of the eyes), cerebellar disorders. Limited eye movement through the six cardinal fields of gaze, increased intracranial pressure.
Paralytic strabismus, paralysis of the oculomotor, trochlear, or abducens nerves |
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| CN III (oculomotor) CN IV (trochlear) CN VI (abducens) |
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Test 3: Assess pupillary response to light (direct and indirect) and accommodation in both eyes Normal Result: Bilateral illuminated pupils constrict simultaneously. Pupil opposite the one illuminated constricts simultaneously.Abnormal Result: Some abnormalities and their implications follow: Dilated pupil (6 to 7 mm), oculomotor nerve paralysis. Argyll Robertson pupils, CNS syphilis, meningitis, brain tumor, alcoholism. Constricted, fixed pupils, narcotics abuse or damage to the pons. Unilaterally dilated pupil unresponsive to light or accommodation, damage to cranial nerve III (oculomotor). Constricted pupil unresponsive to light or accommodation, lesions of the sympathetic nervous system.
Bilateral muscle weakness is seen with peripheral or central nervous system dysfunction. Unilateral weakness may indicate a lesion of cranial nerve V (trigeminal). |
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| Function: Carries sensory impulses of pain, touch, and temperature from the face to the brain; Influences clenching and lateral jaw movements (biting, chewing) Test 1: Test motor function. Ask the client to clench the teeth while you palpate the temporal and masseter muscles for contractionNormal Result: Temporal and masseter muscles contract bilaterally.Abnormal Result: Tip: This test may be difficult to perform and evaluate in the client without teeth. |
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| Test 2: Test sensory function. Tell the client: “I am going to touch your forehead, cheeks, and chin with the sharp or dull side of this safety pin or paper clip (a paper clip is less hazardous). Please close your eyes and tell me if you feel a sharp or dull sensation. Also tell me where you feel it”. Vary the sharp and dull stimulus in the facial areas and compare sides. Repeat test for light touch with a wisp of cotton.Normal Result: The client correctly identifies sharp and dull stimuli and light touch to the forehead, cheeks, and chin.Abnormal Result: Inability to feel and correctly identify facial stimuli occurs with lesions of the trigeminal nerve or lesions in the spinothalamic tract or posterior columns.Tip: To avoid transmitting infection, use a new object with each client. Avoid “stabbing” the client with the object's sharp side. |
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| Test 3: Test corneal reflex. Ask the client to look away and up while you lightly touch the cornea with a fine wisp of cotton. Repeat on the other side.Normal Result: Eyelids blink bilaterally.Abnormal Result: An absent corneal reflex may be noted with lesions of the trigeminal nerve or lesions of the motor part of cranial nerve VII (facial).Tip: This reflex may be absent or reduced in clients who wear contact lenses. |
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Function: Contains sensory fibers for taste on anterior two thirds of tongue and stimulates secretions from salivary glands (submaxillary and sublingual) and tears from lacrimal glands; Supplies the facial muscles and affects facial expressions (smiling, frowning, closing eyes) Test: Test motor function. Ask the client to - Smile, Frown and wrinkle forehead, Show teeth, Puff out cheeks, Purse lips, Raise eyebrows, Close eyes tightly against resistance
Normal Result: Client smiles, frowns, wrinkles forehead, shows teeth, puffs out cheeks, purses lips, raises eyebrows, and closes eyes against resistance. Movements are symmetrical.Abnormal Result: Inability to close eyes, wrinkle forehead, or raise forehead along with paralysis of the lower part of the face on the affected side is seen with Bell's palsy (a peripheral injury to cranial nerve VII [facial]). Paralysis of the lower part of the face on the opposite side affected may be seen with a central lesion that affects the upper motor neurons such as from CVA. |
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Test 2:** Sensory function is not routinely tested. If it is, however, touch the anterior two-thirds of the tongue with a moistened applicator dipped in salt, sugar, or lemon juice and ask the client to identify the flavor. If the client is unsuccessful, repeat the test using one of the other solutions. If needed, repeat the test using the remaining solution.Normal Result: Client identifies correct flavor. In some older clients, the sense of taste may be decreased.
Abnormal Result: Inability to identify correct flavor on anterior two-thirds of the tongue suggests impairment of cranial nerve VII (facial).Tip: Make sure the client leaves the tongue protruded to identify the flavor. Otherwise the substance may move to the posterior third of the tongue (vagus nerve innervation). The posterior portion is tested similarly to evaluate functioning of cranial nerves IX and X. The client should rinse the mouth with water between each taste test. |
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| CN VIII (acoustic, vestibulocochlear) |
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| Function: Contains sensory fibers for hearing and balance Test: Test the client's hearing ability in each ear and perform the Weber and Rinne tests to assess the cochlear (auditory) component of cranial nerve VIII, Ear Assessment, for detailed procedures). Note: The vestibular component, responsible for equilibrium, is not routinely tested. In comatose clients, the test is used to determine integrity of the vestibular system. (See a neurology textbook for detailed testing procedures.) Ø Weber’s Test: Ø Rinne Test: Normal Result: Client hears whispered words from 1 to 2 feet. Weber test: Vibration heard equally well in both ears. Rinne test: AC > BC (air conduction is twice as long as bone conduction).Abnormal Result: Vibratory sound lateralizes to good ear in sensorineural loss. Air conduction is longer than bone conduction but not twice as long, in a sensorineural loss |
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| Function: Contains sensory fibers for taste on posterior third of tongue and sensory fibers of the pharynx that result in the “gag reflex” when stimulated; Provides secretory fibers to the parotid salivary glands; promotes swallowing movements |
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| Function: Carries sensations from the throat, larynx, heart, lungs, bronchi, gastrointestinal tract, and abdominal visceraPromotes swallowing, talking, and production of digestive juices Test 1: Test motor function with phonation. Ask the client to open mouth wide and say “ah” while you use a tongue depressor on the client's tongueNormal Result: Uvula and soft palate rise bilaterally and symmetrically on phonation.Abnormal Result: Soft palate does not rise with bilateral lesions of cranial nerve X (vagus). Unilateral rising of the soft palate and deviation of the uvula to the normal side are seen with a unilateral lesion of cranial nerve X (vagus). |
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| Test 2: Test the gag reflex by touching the posterior pharynx with the tongue depressor. Warn the client that you are going to do this and that the test may feel a little uncomfortable.Normal Result: Gag reflex intact. Some normal clients may have a reduced or absent gag reflex.Abnormal Result: An absent gag reflex may be seen with lesions of cranial nerve IX (glossopharyngeal) or X (vagus). |
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| CN X (vagus) CN IX (glossopharyngeal) |
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| Test 3: Check the client's ability to swallow by giving the client a drink of water. Also note the client's voice quality.Normal Result: Client swallows without difficulty. No hoarseness noted.Abnormal Result: Dysphagia or hoarseness may indicate a lesion of cranial nerve IX (glossopharyngeal) or X (vagus) or other neurologic disorder. |
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| Function: Innervates neck muscles (sternocleidomastoid and trapezius) that promote movement of the shoulders and head rotation. Also promotes some movement of the larynx Test 1: Ask the client to shrug the shoulders against resistance to assess the trapezius muscleNormal Result: There is symmetric, strong contraction of the trapezius muscles.Abnormal Result: Asymmetric muscle contraction or drooping of the shoulder may be seen with paralysis or muscle weakness due to neck injury or torticollis. |
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| Test 2: Ask the client to turn the head against resistance, first to the right then to the left, to assess the sternocleidomastoid muscleNormal Result: There is strong contraction of sternocleidomastoid muscle on side opposite the turned face.Abnormal Result: Atrophy with fasciculations may be seen with peripheral nerve disease. |
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| Function: Innervates tongue muscles that promote the movement of food and talking Test: To assess strength and mobility of the tongue, ask the client to protrude tongue, move it to each side against the resistance of a tongue depressor, then put it back in the mouth.Normal Result: Tongue movement is symmetric and smooth and bilateral strength is apparent.Abnormal Result: Fasciculations and atrophy of the tongue may be seen with peripheral nerve disease. Deviation to the affected side is seen with a unilateral lesion. |
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