**Question:** Dura is supplied by all cranial nerves except -

A. Facial (CN VII)
B. Vestibulocochlear (CN VIII)
C. Trigeminal (CN V)
D. Hypoglossal (CN XII)

**Core Concept:**

The dura mater is a tough, fibrous membrane that forms a part of the meningeal layer surrounding the brain and spinal cord in the central nervous system (CNS). It receives blood supply from various cranial nerves, except for a few specific ones. The cranial nerves are a group of 12 nerves that originate directly from the brain or brainstem and play crucial roles in sensory, motor, and autonomic functions.

**Why the Correct Answer is Right:**

The dura mater is supplied by various cranial nerves, which are essential for different functions in the human body. However, among the given options, the right answer is "Hypoglossal nerve" (CN XII), as it does not contribute to the blood supply of the dura mater. The hypoglossal nerve is primarily associated with the movement of the tongue muscles, ensuring proper tongue mobility for speech and swallowing functions.

**Why Each Wrong Option is Incorrect:**

The remaining options represent cranial nerves that do supply the dura mater.

A. Facial nerve (CN VII) - This nerve is involved in facial movements and sensory functions, but it contributes to the blood supply of the dura mater.
B. Vestibulocochlear nerve (CN VIII) - This nerve is responsible for hearing and balance functions but also supplies the dura mater.
C. Trigeminal nerve (CN V) - This nerve is involved in sensory functions of the face but also supplies the dura mater.

**Clinical Pearl:**

Understanding the anatomy of the cranial nerves is crucial for clinical practice, as misidentification or dysfunction of these nerves can lead to various neurological symptoms. For example, lesions involving the trigeminal nerve can cause facial pain, gustatory sweating (salivation), and loss of sensation in the distribution of the sensory branch. Recognizing these relationships between cranial nerves and their target tissues helps in diagnosing and treating neurological disorders accurately.