H.A LAB

• The nurse needs to be aware of specific nerve functions and assessment Methods for each cranial nerve to detect abnormalities
• Motor Function

  Neurologic assessment of the motor system evaluates proprioception and cerebellar function. Structures involved in proprioception are the proprioceptors, the posterior columns of the spinal cord, the cerebellum, and the vestibular apparatus (which is innervated by cranial nerve VIII) in the labyrinth of the internal ear.
• Sensory Function


  Sensory functions include touch, pain, temperature, position, and tactile discrimination. The first three are routinely tested. Generally, the face, arms, legs, hands, and feet are tested for touch and pain, although all parts of the body can be tested.
• CN I: OLFACTORY

  1. Have client sit in a comfortable position at your eye level

  2. Ask the client to clear the nose to remove any mucus

  3. Close eyes, occlude one nostril, and identify a scented object that you are holding such as soap, vinegar, coffee, or vanilla
• Normal (CN I: OLFACTORY)


  • Client correctly identifies the scent presented to each nostril
  • Some older clients' sense of smell may be decreased
• Deviations from normal (CN I: OLFACTORY)


  • inability to smell or identify the correct scent
  • may indicate olfactory tract lesion
  • congenital, nasal or sinus problems
• CN II – OPTIC


  1. Assess distance vision by asking the client to wear corrective lenses, unless they are used for reading only (i.e., for distances of only 36 cm [14 in.])

  2. Ask the client to stand or sit 6 m (20 ft) from an eye chart, cover the eye not being tested, and identify the letters or characters on the chart

  3. Take three readings: right eye, left eye, both eyes. Record the readings of each eye and both eyes (i.e., the smallest line from which the client is able to read one- half or more of the letters)

  4. Ask the client to read a newspaper or magazine paragraph to assess near vision
• Normal (CN II – OPTIC)


  • Client has 20/20 vision OD (right eye) and OS (left eye) – (distance vision)
  • reads print at 14 inches without difficulty
  • until the patient is in the late 30s to the late 40s, reading is generally possible at a distance of 14 inches
• Deviations from normal (CN II – OPTIC)


  • difficulty reading the Snellen chart
  • Denominator of 40 or more on Snellen-type chart with corrective lenses
  • missing letters
  • Squinting
  • reads print by holding closer than 14 inches or holds print farther away as in presbyopia, which occurs with aging
• Visual Fields


  1. Have the client sit directly facing you at a distance of 60 to 90 cm (2 to 3 ft)

  2. Ask the client to cover the right eye with a card and look directly at your nose

  3. Cover or close your eye directly opposite the client's covered eye (i.e., your left eye), and look directly at the client's nose

  4. Hold an object (e.g., a penlight or pencil) in your fingers, extend your arm, and move the object into the visual field from various points in the periphery. The object should be at an equal distance from the client and yourself. Ask the client to tell you when the moving object is first spotted

  5. To test the temporal field of the left eye, extend and move your right arm in from the client's right periphery

  6. To test the upward field of the left eye, extend and move the right arm down from the upward periphery

  7. To test the downward field of the left eye, extend and move the right arm up from the lower periphery

  8. To test the nasal field of the left eye, extend and move your left arm in from the periphery
• Normal (Visual Fields)


  • normal peripheral vision
  • Temporally, peripheral objects can be seen at right angles (90°) to the central point of vision
  • The upward field of vision is normally 50°, because the orbital ridge is in the way
  • The downward field of vision is normally 70°, because the cheekbone is in the way
• Deviations from normal (Visual Fields)


  Loss of visual fields may be seen in retinal damage or detachment, lesions of the optic nerve and lesions of the parietal cortex
• CN III, IV, VI – OCULOMOTOR, TROCHLEAR, ABDUCENS


  1. Stand directly in front of the client and hold the penlight at a comfortable distance, such as 30 cm (1 ft) in front of the client's eyes

  2. Move the penlight in a slow, orderly manner through the six cardinal fields of gaze, that is, from the center of the eye along the lines of the arrows in and back to the center

  3. Stop the movement of the penlight periodically so that nystagmus can be detected

  4. Inspect the pupils for color, shape, and symmetry of size

  5. Shine a light on the pupil. Observe the response of the illuminated pupil. It should constrict (direct response)

  6. Shine the light on the pupil again, and observe the response of the other pupil. It should also constrict (consensual response)

  7. Hold an object (a penlight or pencil) about 10 cm (4 in.) from the bridge of the client's nose. Ask the client to look first at the top of the object and then at a distant object (e.g., the far wall) behind the penlight. Alternate the gaze from the near to the far object. Observe the pupil's response
• Normal (CN III, IV, VI – OCULOMOTOR, TROCHLEAR, ABDUCENS)


  • Both eyes coordinated, move in unison, with parallel alignment
  • Illuminated pupil constricts (direct response)
  • Nonilluminated pupil constricts (consensual response)
  • Response is brisk
  • Pupils constrict when looking at near object; pupils dilate when looking at far object
  • Pupils converge when near object is moved toward nose
• Deviations from Normal (CN III, IV, VI – OCULOMOTOR, TROCHLEAR, ABDUCENS)


  • Eye movements not coordinated or parallel; one or both eyes fail to follow a penlight in specific directions, e.g., strabismus (cross-eye)
  • Nystagmus (rapid involuntary rhythmic eye movement) other than at end point may indicate neurologic impairment
  • Neither pupil constricts
  • Unequal responses
  • Response is sluggish
  • Absent responses
  • One or both pupils fail to constrict, dilate, or converge
• CN V – TRIGEMINAL


  1. Ask the client to clench the teeth while you palpate the temporal and masseter muscles for contraction

  2. Tell the client: "I am going to touch your forehead, cheeks, and chin with the sharp or dull side of this paper clip. Please close your eyes and tell me if you feel a sharp or dull sensation. Also tell me where you feel it"

  3. Vary the sharp and dull stimulus in the facial areas and compare sides. Repeat test for light touch with a wisp of cotton

  4. 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 (CN V – TRIGEMINAL)


  • Temporal and masseter muscles contract bilaterally
  • Correctly identifies sharp and dull stimuli and light touch to the forehead, cheeks, and chin
  • Eyelids blink bilaterally
• Deviations from normal (CN V – TRIGEMINAL)


  • Decreased contraction in one of both sides
  • Asymmetric strength in moving the jaw may be seen with lesion or injury of the 5th cranial nerve
  • Pain occurs with clenching of the teeth
  • Inability to feel and correctly identify facial stimuli
  • lesions of the trigeminal nerve
  • lesions in the spinothalamic tract or posterior columns
  • Absent corneal reflex
  • lesions of the trigeminal nerve
  • lesions of the motor part of cranial nerve VII (facial)
• CN VII – FACIAL


  1. Ask the patient to Smile

  2. Frown and wrinkled forehead

  3. Show teeth

  4. Puff out cheeks

  5. Purse lips

  6. Raise eyebrows

  7. Close eyes tightly against resistance

  8. Touch the anterior two-thirds of the tongue with a moistened applicator dipped in salt, sugar, or lemon juice
• Normal (CN VII – FACIAL)

  • smiles, frowns, wrinkles forehead, shows teeth, puffs out cheeks, purses lips, raises eyebrows, and closes eyes against resistance
  • movements are symmetric
  • identifies the correct flavor
• Deviations from normal (CN VII – FACIAL)

  • Inability to close eyes, wrinkle forehead, or raise forehead along with paralysis of the lower part of the face on the affected side
  • 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
  • inability to identify correct flavor on anterior two-thirds of the tongue
• CN VIII – AUDITORY

  1. Hold the tuning fork at its base. Activate it by tapping the fork gently against the back of your hand near the knuckles or by stroking the fork between your thumb and index fingers. It should be made to ring softly

  2. Place the base of the vibrating fork on top of the client's head and ask where the client hears the noise

  3. Hold the handle of the activated tuning fork on the mastoid process of one ear until the client states that the vibration can no longer be heard. Immediately hold the still vibrating fork prongs in front of the client's ear canal. Ask whether the client now hears the sound

  4. Ask the client to stand with feet together and arms resting at the sides, first with eyes open, then closed
• Normal (CN VIII – AUDITORY)

  • Sound is heard in both ears or is localized at the center of the head (Weber negative)
  • Sound conducted by air is heard more readily than sound conducted by bone. The tuning fork vibrations conducted by air are normally heard longer
  • Negative Romberg: may sway slightly but is able to maintain an upright posture and foot stance
• Deviations from Normal (CN VIII – AUDITORY)

  • Sound is heard better in impaired ear, indicating a bone-conductive hearing loss; or sound is heard better in ear without a problem, indicating a sensorineural disturbance (Weber positive)
  • Positive Romberg: cannot maintain foot stance; moves the feet apart to maintain stance. If the client cannot maintain balance with the eyes shut, the client may have sensory ataxia (lack of coordination of the voluntary muscles)
• CN IX, X – GLOSSOPHARYNGEAL, VAGUS

  1. Ask the client to open mouth wide and say "ah" while you use a tongue depressor on the client's tongue

  2. Giving the client a drink of water

  3. Note the voice quality
• Normal (CN IX, X – GLOSSOPHARYNGEAL, VAGUS)

  • Uvula and soft palate rise bilaterally and symmetrically on phonation
  • Swallows without difficulty
  • No hoarseness noted
• Deviations from Normal (CN IX, X – GLOSSOPHARYNGEAL, VAGUS)

  • Soft palate does not rise
  • Unilateral rising of the soft palate and deviation of the uvula to the normal side
  • Dysphagia or hoarseness
  • lesion of cranial nerve IX (glossopharyngeal) or X (vagus)
  • neurologic disorder
• CN XI – SPINAL ACCESSORY

  1. Ask the client to shrug the shoulders against resistance to assess the trapezius muscle

  2. Ask the client to turn the head against resistance, first to the right and then to the left, to assess the sternocleidomastoid muscle
• Normal (CN XI – SPINAL ACCESSORY)


  • Symmetric strong contraction of the trapezius muscles
  • strong contraction of the sternocleidomastoid muscle on the side opposite the turned face
• Deviations from normal (CN XI – SPINAL ACCESSORY)

  • Asymmetric muscle contraction or drooping of the shoulder
  • paralysis or muscle weakness due to neck injury or torticollis
  • Atrophy with fasciculations may be seen with peripheral nerve disease
• CN XII – HYPOGLOSSAL

  Ask the client to protrude tongue, move it to each side against the resistance of a tongue depressor, and then put it back in the mouth
• Normal (CN XII – HYPOGLOSSAL)

  Tongue movement is symmetric and smooth, and bilateral strength is apparent
• Deviations from normal (CN XII – HYPOGLOSSAL)

  • Fasciculations and atrophy of the tongue
  • peripheral nerve disease
  • Deviation to the affected side
  • unilateral lesion
• Note all the Normal and Deviations from normal findings then refer accordingly