Cranial nerves

NOTE

1. general somatic afferents subserve tactile sense, vibration sense, pain and temperature senses and jaw proprioception
2. general visceral afferents mediate visceral sensations and chemoreception from body organs
3. general somatic motor fibers innervate striated muscle developing from somites (axial skeleton of head and trunk)
4. general visceral motor fibers are the axons of autonomic preganglionic neurons
5. special somatic afferents subserve vision, auditory and balance
6. special visceral afferents mediate taste and smell (mucous membrane sensors)
7. special visceral motor fibers innervate striated muscle developing from brachial arches
   1. first brachial arch – trigeminal nerve and nuclei
   2. second brachial arch – facial
   3. third brachial arch – glossopharyngeal
   4. fourth brachial arch - vagus

Function

1. smell

• special visceral afferent

2. sees

• special somatic afferent

3. moves eye up, medial, down; contricts pupils

• general somatic efferent (eye movement)
• general visceral efferent (pupil constriction)

4. moves pupil down and in (patients often notice symptoms when walking down stairs; CN 4 is commonly injured in head trauma)

• general somatic efferent

5. chews and feels head and meninges

• general somatic afferent
• special visceral efferent

6. abducts eye

• general somatic motor

7. moves face, tastes, salivates, cries

• special visceral afferent (taste) and efferent (facial expression)
• general visceral efferent (cries and salivates)
• general somatic afferent (sensation from ear)

8. hears, regulates balance

• special somatic afferent

9. tastes, salivates, swallows, monitors carotid body and sinus

• special visceral efferent (swallowing and coughing), general somatic afferent (pain sensation from inner ear and pharynx), general visceral afferent (carotid sinus), special visceral afferent (taste), general visceral efferent (salivation from parotid gland)

10. tastes, swallows, lifts palate, talks, communicates with viscera

• special visceral efferent (muscle of pharynx and larynx) and general visceral efferent (innervating heart, lung, esophagus and stomach), special visceral afferent (taste and chemoreceptors), general visceral afferent (baroreceptors)

11. turns head, lifts shoulders

• general somatic efferent

12. moves tongue

• general somatic efferent

Function summary

1. sensory: 1,2,8
2. motor: 3,4,6,11,12
3. mixed:
   1. CN 5 – motor nucleus and sensory nucleus of CN 5
      1. Motor nucleus is confined to pons
   2. CN 7 – facial nucleus, superior salivatory nucleus, nucleus solitarius, and sensory nucleus of CN 5
   3. CN 9 – nucleus ambiguous, inferior salivatory nucleus, nucleus solitarius, sensory nucleus of CN 5
   4. CN 10 – nucleus ambiguous, dorsal motor nucleus, nucleus solitarius, sensory nucleus of CN 5
      1. Nucleus ambiguous, solitarius, and dorsal motor nucleus are confined to medulla
   5. Remember: Solitarius is Sensory (taste and viscera), aMbiguous is Motor (elevates palate, swallows, shoulder and neck movement, visceral movement); ambiguous is just anterior to solitarius and makes contributions to CN 9, 10, and 11; in general, motor nuclei are anterior and medial while sensory nuclei are lateral and posterior