Question

Gag reflex test is carried out to test the cranial nerve namely

• A. Glossopharyngeal
• B. Oculomotor
• C. Trochlear
• D. Facial

Hint:

Cranial Nerve Reflexes:
Gag Reflex $\rightarrow$ CN IX (Glossopharyngeal) & CN X (Vagus).
Menace Response $\rightarrow$ CN II (Optic) & CN VII (Facial).
Palpebral Reflex $\rightarrow$ CN V (Trigeminal) & CN VII.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The pharyngeal gag reflex tests the integrity of the sensory afferents of the glossopharyngeal nerve (CN IX) and motor efferents of the vagus nerve (CN X).
Key Formula or Approach:
\[ \text{Gag Reflex Arc: Sensory Afferent } \xrightarrow{\text{CN IX (Glossopharyngeal)}} \text{Medulla} \xrightarrow{\text{CN X (Vagus)}} \text{Pharyngeal Constrictor Muscles} \]

Step 2: Detailed Explanation:
In clinical veterinary neurological examination:
- The Gag (Pharyngeal) Reflex is elicited by stimulating the caudal pharyngeal mucosa or base of the tongue with a tongue depressor or finger, evoking pharyngeal contraction and swallowing.
- Sensory afferent innervation is supplied primarily by the Glossopharyngeal Nerve (Cranial Nerve IX), with somatic motor efferent branches supplied by the Vagus Nerve (Cranial Nerve X).
- Therefore, the test evaluates the functional integrity of the Glossopharyngeal nerve (CN IX).

Step 3: Final Answer:
Hence, the gag reflex tests the Glossopharyngeal cranial nerve, matching option (A).