Cranial Nerves

1
Cranial Nerves

• I through XII

2
Olfactory Nerve I

• Sense of smell
• Damage causes impaired sense of smell

3
Optic Nerve II

• Provides vision
• Damage causes blindness in visual field

4
Oculomotor Nerve III

• Somatic and Autonomic motor function
• Eye movement (Superior, inferior, medial rectus
  muscles and inferior oblique muscle), opening of
  eyelid (levator palpebrae superioris),
  constriction of pupil (circular muscle), focusing
  (ciliary muscle and accomodation)
• Damage causes drooping eyelid, dilated pupil,
  double vision, difficulty focusing and inability
  to move eye in certain directions

5
Trochlear Nerve IV

• Eye movement (superior oblique muscle)
• Damage causes double vision and inability to
  rotate eye inferolaterally

6
Trigeminal Nerve V

• Ophthalmic branch sensations from nasal cavity,
  skin of forehead, upper eyelid, eyebrow, nose
• Maxillary branch sensations from lower eyelid,
  upper lips and gums, teeth of the maxilla, cheek,
  nose, palate, pharynx
• Mandibular branch sensations from teeth of the
  mandible, lower gums and lips, palate, tongue.
  Motor function of temporalis and masseter
  muscles.
• Damage produces loss of sensation and impaired
  chewing

7
Abducens Nerve VI

• Provides eye movement (lateral rectus m.)
• Damage results in inability to rotate eye
  laterally and at rest eye rotates medially

8
Facial Nerve VII

• Somatic Motor - facial expressions
• Autonomic Motor - salivary and lacrimal glands,
  mucous membranes of nasal and palatine mucosa
• Special Sensory - taste on anterior 2/3s of
  tongue
• Damage produces sagging facial muscles and
  disturbed sense of taste (no sweet and salty)

9
Branches of Facial Nerve
Clinical test Test anterior 2/3s of tongue with
substances such as sugar, salt, vinegar, and
quinine test response of tear glands to ammonia
fumes test motor functions by asking subject to
close eyes, smile, whistle, frown, raise
eyebrows, etc.
10
Vestibulocochlear Nerve VIII

• Special Sensory
• Provides hearing (cochlear branch) and sense of
  balance (vestibular branch)
• Damage produces deafness, dizziness, nausea, loss
  of balance and nystagmus

11
Glossopharyngeal Nerve IX

• Somatic motor Swallowing and voice production
  via pharyngeal muscles
• Autonomic motor - salivation, gagging, control of
  BP and respiration
• Sensations from posterior 1/3 of tongue including
  taste
• Sensations from baroreceptors and chemoreceptors
• Damage results in loss of bitter and sour taste
  and impaired swallowing, blood pressure anomalies
  (with CN X).

12
Vagus Nerve X

• Sensations from skin at back of ear, external
  acoustic meatus, part of tympanic membrane,
  larynx, trachea, espophagus, thoracic and
  abdominal viscera
• Sensations from bararoceptors and chemoreceptors
• Special sensory taste from epiglottis and
  pharynx
• Somatic motor Swallowing and voice production
  via pharyngeal muscles
• Autonomic motor smooth muscle of abdominal
  viscera, visceral glands secretions, relaxation
  of airways, and normal or decreased heart rate.
• Damage causes hoarseness or loss of voice,
  impaired swallowing, GI dysfunction, blood
  pressure anomalies (with CN IX), fatal if both
  are cut

13
Accessory Nerve IX

• Swallowing, head, neck and shoulder movement via
  trapezius and sternocleidomastoid and pharyngeal
  muscles
• Damage causes impaired head, neck, shoulder
  movement

14
Hypoglossal Nerve XII

• Tongue movements for speech, food manipulation
  and swallowing
• If both are damaged cant protrude tongue
• If one side is damaged tongue deviates towards
  injured side

15
Cranial Nerve Disorders

• Trigeminal neuralgia (tic douloureux)
• recurring episodes of intense stabbing pain in
  trigeminal nerve area (near mouth or nose)
• pain triggered by touch, drinking, washing face
• treatment may require cutting nerve
• Bells palsy
• disorder of facial nerve causes paralysis of
  facial muscles on one side
• may appear abruptly with full recovery within
  3-5 weeks