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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