Neurological

• 12 Cranial Nerves & Their Functions

  • I (olfactory)
  • II (optic)
  • III (oculomotor)
  • IV (trochlear)
  • V (trigeminal)
  • VI (abducens)
  • VII (facial)
  • VIII (acoustic, vestibulocochlear)
  • IX (glossopharyngeal)
  • X (vagus)
  • XI (spinal accessory)
  • XII (hypoglossal)
• Cranial Nerve I (olfactory)

  Carries smell impulses from nasal mucous membrane to brain
• Cranial Nerve II (optic)


  Carries visual impulses from eye to brain
• Cranial Nerve III (oculomotor)


  Contracts eye muscles to control eye movements (interior lateral, medial, and superior), constricts pupils, and elevates eyelids
• Cranial Nerve IV (trochlear)


  Contracts one eye muscle to control inferomedial eye movement
• Cranial Nerve V (trigeminal)

  Carries sensory impulses of pain, touch, and temperature from the face to the brain. Influences clenching and lateral jaw movements (biting, chewing)
• Cranial Nerve VI (abducens)


  Controls lateral eye movements
• Cranial Nerve VII (facial)

  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)
• Cranial Nerve VIII (acoustic, vestibulocochlear)


  Contains sensory fibers for hearing and balance
• Cranial Nerve IX (glossopharyngeal)


  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
• Cranial Nerve X (vagus)


  Carries sensations from the throat, larynx, heart, lungs, bronchi, gastrointestinal tract, and abdominal viscera. Promotes swallowing, talking, and production of digestive juices
• Cranial Nerve XI (spinal accessory)


  Innervates neck muscles (sternocleidomastoid and trapezius) that promote movement of the shoulders and head rotation. Also promotes some movement of the larynx
• Cranial Nerve XII (hypoglossal)


  Innervates tongue muscles that promote the movement of food and talking
• Olfactory Nerve (CN I) Assessment


  1. Have client sit in a comfortable position 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, coffee, or vanilla

  4. Repeat procedure for the other nostril
• Normal Olfactory Nerve (CN I) Assessment


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

  • Neurogenic Anosmia - inability to smell or identify the correct scent, may indicate olfactory tract lesion, frontal lobe tumor, congenital, nasal or sinus problems, nerve tissue injury, smoking and use of cocaine
• Optic Nerve (CN II) Assessment

  Use a Snellen chart to assess vision in each eye
• Normal Optic Nerve (CN II) Assessment

  • Client has 20/20 vision OD (right eye) and OS (left eye) – (distance vision)
• Deviations from normal Optic Nerve (CN II) Assessment

  • Difficulty reading Snellen chart, missing letters, squinting
• Oculomotor (CN III), Trochlear (CN IV), Abducens (CN VI) Nerves Assessment

  1. Inspect margins of the eyelids of each eye

  2. Assess extraocular movements

  3. Assess pupillary response to light (direct and indirect) and accommodation in both eyes
• Normal Oculomotor (CN III), Trochlear (CN IV), Abducens (CN VI) Nerves Assessment

  • Eyelid covers about 2 mm of the iris
  • Eyes move in a smooth, coordinated motion in all directions (the six cardinal fields)
  • Bilateral illuminated pupils constrict simultaneously
  • Pupil opposite the one illuminated constricts simultaneously
• Deviations from normal Oculomotor (CN III), Trochlear (CN IV), Abducens (CN VI) Nerves Assessment

  • Ptosis (drooping of the eyelid) is seen with weak eye muscles, may indicate myasthenia gravis
  • Abnormal eye movements may indicate cerebellar disorders, increased ICP, or paralytic strabismus
• Trigeminal Nerve (CN V) Assessment - Motor Function


  Ask the client to clench the teeth while you palpate the temporal and masseter muscles for contraction
• Normal Trigeminal Nerve (CN V) Motor Function

  • Temporal and masseter muscles contract bilaterally
• Deviations from normal Trigeminal Nerve (CN V) Motor Function

  • 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
• Trigeminal Nerve (CN V) Assessment - Sensory Function


  1. 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"

  2. Vary the sharp and dull stimulus in the facial areas and compare sides. Repeat test for light touch with a wisp of cotton
• Normal Trigeminal Nerve (CN V) Sensory Function


  • Correctly identifies sharp and dull stimuli and light touch to the forehead, cheeks, and chin
• Deviations from normal Trigeminal Nerve (CN V) Sensory Function

  • Inability to feel and correctly identify facial stimuli, may indicate lesions of the trigeminal nerve or lesions in the spinothalamic tract or posterior columns
• Trigeminal Nerve (CN V) Assessment - Corneal Reflex


  1. Ask the client to look away and up while you lightly touch the cornea with a fine wisp of cotton

  2. Repeat on the other side
• Normal Trigeminal Nerve (CN V) Corneal Reflex


  • Eyelids blink bilaterally
• Deviations from normal Trigeminal Nerve (CN V) Corneal Reflex


  • Absent corneal reflex, may indicate lesions of the trigeminal nerve or lesions of the motor part of cranial nerve VII (facial)
• Facial Nerve (CN VII) Assessment - Motor Function

  1. Smile

  2. Frown and wrinkle forehead

  3. Show teeth

  4. Puff out cheeks

  5. Purse lips

  6. Raise eyebrows

  7. Close eyes tightly against resistance
• Normal Facial Nerve (CN VII) Motor Function


  • Smiles, frowns, wrinkles forehead, shows teeth, puffs out cheeks, purses lips, raises eyebrows, and closes eyes against resistance
  • Movements are symmetric
• Deviations from normal Facial Nerve (CN VII) Motor Function


  • Inability to close eyes, wrinkle forehead, or raise forehead along with paralysis of the lower part of the face on the affected side, may indicate Bell's Palsy
  • 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, may indicate Stroke
• Facial Nerve (CN VII) Assessment - Sensory Function

  1. Touch the anterior two-thirds of the tongue with a moistened applicator dipped in salt, sugar, or lemon juice

  2. Ask the client to identify the flavor
• Normal Facial Nerve (CN VII) Sensory Function


  • Identifies correct flavor
• Deviations from normal Facial Nerve (CN VII) Sensory Function


  • Inability to identify correct flavor on anterior two-thirds of the tongue, may indicate impairment of cranial nerve VII
• Acoustic/Vestibulocochlear Nerve (CN VIII) Assessment

  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
• Normal Acoustic/Vestibulocochlear Nerve (CN VIII) Assessment

  • Client hears whispered words from 1–2 feet
  • Weber test: Vibration heard equally well in both ears
  • Rinne test: AC > BC
• Deviations from normal Acoustic/Vestibulocochlear Nerve (CN VIII) Assessment

  • Vibratory sound lateralizes to good ear in sensorineural loss
  • Air conduction is lesser than twice the bone conduction