Chapter 7 - Lower cranial nerve function

Questions

Define the following terms:

dysarthria, dysphonia, dysphagia.
Dysarthria is the inability to speak clearly due to problems with control of the motor apparatus of speech (generation and understanding of language should be normal and reading/writing are unaffected).
Dysphonia is problems with speech due to disorders of the vocal apparatus in the larynx (laryngitis is an example).
Dysphagia is difficulty with swallowing.

7-1. What are the main functions of the glossopharyngeal nerve?

Answer 7-1. The glossopharyngeal nerve provides sensation to the carotid baroreceptor and chemoreceptor, the pharynx and the middle ear.

7-2. What would be the effect on soft palate movement of unilateral damage to the vagus nerve?

Answer 7-2. The vagus nerve activates the elevator of the soft palate. The palate will elevate with deviation of base of uvula away from the side of lesion (toward the intact side).

7-3. What would be the effect of unilateral damage to the vagus nerve on larynx function?

Answer 7-3. The vagus (recurrent laryngeal) innervates larynx muscle. Damage would produce painless hoarseness, with weakness or paralysis of the vocal cord on that side.

7-4. Describe the course of the spinal accessory nerve.

Answer 7-4. The spinal accessory nerve comes from cervical spinal cord, enters the head through foramen magnum and exits through jugular foramen.

7-5. What does the spinal accessory nerve innervate?

Answer 7-5. CN XI innervates the SCM and trapezius muscles.

7-6. What does the hypoglossal nerve innervate?

Answer 7-6. The hypoglossal nerve innervates the tongue.

7-7. What would be the findings in unilateral damage to the hypoglossal nerve?

Answer 7-7. The tongue deviates toward the side of weakness when protruded and it will be weak when attempting to push against the cheek on the strong side of tongue. With time, there would be atrophy of the tongue on the side of the nerve damage.

7-8. What would be the effect of a large stroke in the motor cortex on tongue movement?

Answer 7-8. Corticobulbar damage (like a stroke) will slightly weaken the contralateral side of the tongue.

7-9. What is the reflex pathway of the gag reflex?

Answer 7-9. Gag reflex - afferent is glossopharyngeal, efferent is vagus. It is a consensual reflex.

7-10. What is the reflex pathway of the cough reflex?

Answer 7-10. The cough reflex - afferent is vagus, efferent is complex including respiration centers and vagus.

7-11. What is the reflex pathway of the baroreceptor reflex?

Answer 7-11. The baroreceptor reflex - afferent is glossopharyngeal, efferent is vagus.