1. THE NERVOUS SYSTEM
JOSE S. SANTIAGO M.D.

2. Cranial Nerves 12 pairs of nerves that mostly serve the head and neck
Numbered in order, front to back
Most are mixed nerves, but three are sensory only

3. Cranial Nerves I Olfactory nerve – sensory for smell
II Optic nerve – sensory for vision
III Oculomotor nerve – motor fibers to
eye muscles
IV Trochlear nerve – motor fiber to eye muscles (superior oblique m.)

4. Cranial Nerves
V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles
VI Abducens nerve – motor fibers to eye muscles (lateral rectus m.)
VII Facial nerve – sensory for taste; motor fibers to the face
VIII Vestibulocochlear nerve – sensory for balance and hearing

5. Cranial Nerves
IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx
X Vagus nerve – sensory and motor fibers for pharynx, larynx, and viscera
XI Accessory nerve – motor fibers to neck and upper back (Trapezius and Sternocleidomastoid)
XII Hypoglossal nerve – motor fibers to tongue

6. Examination of Cranial Nerves
I Olfactory nerve – sensory for smell
Test each nostril with essence bottles of coffee, vanilla, peppermint.

7. Examination of Cranial Nerves
II Optic nerve – sensory for vision
With patient wearing glasses, test each eye separately on eye chart/ card using an eye cover.
Examine visual fields by wiggling fingers 1 foot from pt's ears, asking which they see move. • Keep examiner's head level with patient's head.

8. Examination of Cranial Nerves
III Oculomotor nerve
IV Trochlear nerve –(superior oblique m.)
VI Abducens nerve – (lateral rectus m.)
Follow finger with eyes without moving head.
Look at the shape and size of pupils.

9. Examination of Cranial Nerves
V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles
Corneal reflex: patient looks up and away. • Touch cotton wool to other side. • Look for blink in both eyes, ask if can sense it.
Facial sensation: sterile sharp item on forehead, cheek, jaw. • Repeat with dull object. Ask to report sharp or dull.
Motor: pt opens mouth, clenches teeth (pterygoids). • Palpate temporal, masseter muscles as they clench

10. Examination of Cranial Nerves
VII Facial nerve – sensory for taste; motor fibers to the face
Inspect facial droop or asymmetry.
Facial expression muscles: pt looks up and wrinkles forehead.
Pt shuts eyes tightly: compare each side.
Pt grins, frown, show teeth, puff out cheeks.

11. Examination of Cranial Nerves
VIII Vestibulocochlear nerve – sensory for balance and hearing
Ask the patient if he can hear the sound that you make.

12. Examination of Cranial Nerves
IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx
X Vagus nerve – sensory and motor fibers for pharynx, larynx, and viscera
Patient swallows, coughs
Examine palate for uvular displacement.
Patient says "Ah"
Gag reflex [sensory IX, motor X]:

13. Examination of Cranial Nerves
XI Accessory nerve – motor fibers to neck and upper back (Trapezius and Sternocleidomastoid)
From behind, examine for trapezius atrophy, asymmetry.
Pt. shrugs shoulders (trapezius).
Pt. turns head against resistance: watch, palpate SCM on opposite side.

14. Examination of Cranial Nerves
XII Hypoglossal nerve – motor fibers to tongue
Protrude tongue: in unilateral lesions, the tongue deviates to affected side.

15. Distribution of Cranial Nerves
Figure 7.21

16. Aging Loss of myelin sheath (Demyelination)
Impaired coordination
Decreased neuroglia leads to loss of neurons
Muscle weakness, impaired coordination & reflexes, verbal & learning dysfunction, short-term memory loss
Alzheimer’s disease and dementia

17. Common Diseases
Brain tumors
Gliomas (malignant)
Meningiomas (benign)

18. Traumatic Brain Injuries
Concussion
Slight brain injury
No permanent brain damage
Contusion
Nervous tissue destruction occurs
Nervous tissue does not regenerate
Cerebral edema
Swelling from the inflammatory response
May compress and kill brain tissue

19. Upper Motor Neuron Lesions
The lesion is in the brain or above the anterior horn cell of spinal cord
“Spastic paralysis”- paralysis accompanied by severe hypertonia
Examples:
CVA (Stroke)
Traumatic Brain Injuries
Cerebral Palsy

20. Lower Motor Neuron Lesions
The lesion is in the nerve roots, peripheral nerves, or neuromuscular junctions
“Flaccid paralysis”- paralysis accompanied by muscle loss
Examples:
Polio
Botulism
Guillain-Barre Syndrome
Cauda-equina syndrome

21. THANK YOU!