Pediatrics : Cranial Nerves

- - Cranial Nerves
    - I—Olfactory Nerve
      - Olfactory mucosa of nasal cavity (Smell)
        
        With eyes closed, have child identify odors, such as coffee, alcohol from a swab, or other smells; test each nostril separately.
    - II—Optic Nerve
      - Rods and cones of retina, optic nerve (Vision)
        
        Check for perception of light, visual acuity, peripheral vision, color vision, and normal optic disc.
    - III—Oculomotor Nerve
      - Extraocular muscles of eye:
        
        Superior rectus: moves eyeball up and in
        
        Inferior rectus: moves eyeball down and in
        
        Medial rectus: moves eyeball nasally
        
        Inferior oblique: moves eyeball up and out
        
        Have child follow an object (toy) or light in six cardinal positions of gaze
      - Pupil constriction and accommodation
        
        Perform PERRLA (Pupils Equal, Round, React to Light, and Accommodation).
      - Eyelid closing Check for proper placement of eyelid.
    - IV—Trochlear Nerve
      - Superior oblique (SO) muscle: moves eye down and out
        
        Have child look down and in
    - V—Trigeminal Nerve
      - Muscles of mastication
        
        Have child bite down hard and open jaw; test symmetry and strength.
      - Sensory: face, scalp, nasal and buccal mucosa
        
        With child’s eyes closed, see if child can detect light touch in mandibular and maxillary regions.
        
        Test corneal and blink reflex by touching cornea lightly with a whisk of cotton ball twisted into a point (approach from side so the child does not blink before cornea is touched).
    - VI—Abducens Nerve
      - Lateral rectus (LR) muscle: moves eye temporally
        
        Have child look toward temporal side
    - VII—Facial Nerve
      - Muscles for facial expression
        
        Have child smile, make funny face, or show teeth to see symmetry of expression.
      - Anterior two-thirds of tongue (sensory)
        
        Have child identify sweet or salty solution; place each taste on anterior section and sides of protruding tongue; if child retracts tongue, solution will dissolve toward posterior part of tongue.
    - VIII—Auditory, Acoustic, or Vestibulocochlear Nerve
      - Internal ear
      - Hearing and balance
        
        Test hearing; note any loss of equilibrium or presence of vertigo.
    - IX—Glossopharyngeal Nerve
      - Pharynx, tongue
        
        Stimulate posterior pharynx with a tongue blade; child should gag.
      - Posterior third of tongue (Sensory)
        
        Test sense of sour or bitter taste on posterior segment of tongue.
    - X—Vagus Nerve
      - Muscles of larynx, pharynx, some organs of gastrointestinal system, sensory fibers of root of tongue, heart, and lung
        
        Note hoarseness of voice, gag reflex, and ability to swallow.
        
        Check that uvula is in midline; when stimulated with tongue blade, it should deviate upward and to stimulated side.
    - XI—Accessory Nerve
      - Sternocleidomastoid and trapezius muscles of shoulder
        
        Have child shrug shoulders while applying mild pressure; with examiner’s palms placed laterally on child’s cheeks, have child turn head against opposing pressure on either side; note symmetry and strength.
    - XII—Hypoglossal Nerve
      - Muscles of tongue
        
        Have child move tongue in all directions; have child protrude tongue as far as possible; note any midline deviation.
        
        Test strength by placing tongue blade on one side of tongue and having child move it away.
  - Expected findings

	Infants	Children and Adolescents
I Olfactory	Difficult to test	Identifies smells through each nostril individually
II Optic	Looks at face and tracks with eyes	Has intact visual acuity, peripheral vision, and color vision
III Oculomotor	Blinks in response to light Has pupils that are reactive to light	Has no nystagmus and PERRLA is intact
IV Trochlear	Looks at face and tracks with eyes	Has the ability to look down and in with eyes
V Trigeminal	Has rooting and sucking reflexes	Is able to clench teeth together Detects touch on face with eyes closed
VI Abducens	Looks at face and tracks with eyes	Is able to move eyes laterally toward temples
VII Facial	Has symmetric facial movements	Has the ability to differentiate between salty and sweet on tongue Has symmetric facial movements
VIII Acoustic	Tracks a sound Blinks in response to a loud noise	Does not experience vertigo Has intact hearing
IX Glossopharyngeal	Has an intact gag reflex	Has an intact gag reflex Is able to taste sour sensations on back of tongue
X Vagus	Has no difficulties swallowing	Speech clear, no difficulties swallowing Uvula is midline
XI Spinal Accessory	Moves shoulders symmetrically	Has equal strength of shoulder shrug against examiner’s hands
XII Hypoglossal	Has no difficulties swallowing Opens mouth when nares are occluded	Has a tongue that is midline Is able to move tongue in all directions with equal strength against tongue blade resistance

- - Deep tendon reflexes
    - Deep tendon reflexes should demonstrate the following
      - Partial flexion of the lower arm at the bicep tendon
      - Partial extension of the lower arm at the triceps tendon
      - Partial extension of the lower leg at the patellar tendon
      - Plantar flexion of the foot at the Achilles tendon

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Pediatrics : Cranial Nerves

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