**Question:** Malignant otitis externa affects which cranial nerve:

A. Facial (CN VII)
B. Vestibulocochlear (CN VIII)
C. Vagus (CN X)
D. Glossopharyngeal (CN IX)

**Correct Answer:** **D. Glossopharyngeal (CN IX)**

**Core Concept:**
Malignant otitis externa is a serious complication of chronic otitis externa (ear infection), primarily affecting the elderly population due to immunocompromised status or diabetes mellitus. It is characterized by the spread of infection from the outer ear canal to the temporal bone, leading to inflammation and damage of cranial nerves.

**Why the Correct Answer is Right:**
The correct answer (D) is the glossopharyngeal (CN IX) nerve, which plays a crucial role in the pathogenesis of malignant otitis externa. The glossopharyngeal nerve is responsible for the sensory innervation of the ear and the oropharynx. When the infection spreads to the temporal bone, it can damage this nerve, leading to the symptoms and signs seen in malignant otitis externa.

**Why Each Wrong Option is Incorrect:**
A. Facial (CN VII) is incorrect because it is primarily responsible for facial movements and does not innervate the ear or oropharynx, making it less likely to be affected in malignant otitis externa.

B. Vestibulocochlear (CN VIII) is incorrect because it is responsible for hearing and balance functions, which are not directly involved in the pathogenesis of malignant otitis externa.

C. Vagus (CN X) is incorrect as it is primarily responsible for controlling swallowing and cardiovascular functions, making it less relevant to the otorhinolaryngological symptoms and signs associated with malignant otitis externa.

**Clinical Pearl:**
In the context of malignant otitis externa, it is essential for physicians to recognize the symptoms and signs associated with cranial nerve dysfunction, as early diagnosis and intervention can prevent complications and improve patient outcomes. A thorough examination of the ear, nose, throat, and neck is crucial for identifying the condition.

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**Core Concept:**
Malignant otitis externa is a severe complication of chronic otitis externa, a type of bacterial infection affecting the outer ear canal. It is characterized by the spread of infection from the ear canal to the temporal bone, leading to inflammation and damage to cranial nerves.

**Why the Correct Answer is Right:**
The glossopharyngeal nerve (CN IX) is the correct answer because it is responsible for the innervation of the ear and oropharynx, making it directly involved in the pathogenesis of malignant otitis externa. The infection can cause inflammation and damage to the nerve, resulting in the characteristic symptoms and signs seen in malignant otitis externa.

**Why Each Wrong Option is Incorrect:**
A. Facial nerve (CN VII) is incorrect because it controls facial movements and is not directly involved in the otorhinolaryngological symptoms and signs associated with