Lesson 8D: Cranial Nerves

Cranial Nerves

• 12 pairs

• sensory, motor, and mixed nerves

• name and roman numeral to identify the nerves

Olfactory (I) Nerve

• sensory nerve

• sensory of smell

• olfactory cells converge to become olfactory nerve

Optic (II) Nerve

• Sensory Nerve

• Ganglion cells in the retina of each eye join to form an optic nerve

• nerve of vision

Oculomotor (III) Nerve

• motor cranial nerve

• originates in the midbrain

• supply the extrinsic eye muscles to control:

  • movements of the eyeball

    • adduction

    • downward

  • movement of upper eyelid

  • reaction to light

Trochlear (IV) Nerve

• Motor cranial nerve

• smallest of the 12 cranial nerves

• origin: midbrain

• controls downward movement of the eyeball

Trigeminal (V) Nerve

• largest cranial nerve

• mixed nerve

• three branches: opthalmic, maxillary,, and mandibular

• deal with sensation of touch, pain , and temperature

• motor axons supply muscles of mastication

Abducens (VI) Nerve

• motor cranial nerve

• originates from the pons

• cause abduction of the eyeball (lateral rotation)

Facial (VII) Nerve

• mixed cranial nerve

• sensory portion extends from the taste buds of the anterior two-thirds of the tongue

• motor portion arises from the pons and deal with facial expression

Vestibulocochlear (VIII) Nerve

• sensory cranial nerve

• originates in the inner ear

• vestibular branch carries impulses for equilibrium

• cochlear branch carries impulses for hearing

Glossopharyngeal (IX) Nerve

• mixed cranial nerve

• sensory axons carry signals from the taste buds of the posterior one-third of the tongue

• motor neurons arise from the medulla and deal with the release of saliva

Vagus (X) Nerve

• mixed cranial nerve

• distributed from the head and neck into the thorax and abdomen

• sensory neurons deal with a variety of sensations such as proprioception, and stretching

• Motor neurons arise from the medulla and supply muscles of the pharynx, larynx, and soft palate that are involved in swallowing and vocalization

(Spinal) Accessory (XI) Nerve

• motor cranial nerve

• divided into cranial accessory and spinal accessory nerves

• supplies

  • sternocleidomastoid

  • trapezius

Hypoglossal (XII) Nerve

• motor cranial nerve

• conduct nerve impulses for speech and swallowing

Sensory, Motor, or Both?

1. S = Some

2. S = Say

3. M = Marry

4. M = Money

5. B = But

6. M = My

7. B = Brother

8. S = Says

9. B = Big

10. B = Brains

11. M = Matter

12. M = More