Most common nerve involved in intracranial aneurysm is :
**Core Concept**
Intracranial aneurysms are a type of vascular malformation that can lead to subarachnoid hemorrhage and other neurological complications. The nerves involved are often those that are in close proximity to the aneurysm, particularly those that traverse the circle of Willis.
**Why the Correct Answer is Right**
The most common nerve involved in intracranial aneurysm is the Oculomotor nerve (III cranial nerve). This is because the oculomotor nerve runs close to the posterior communicating artery (PComm), which is a common site for aneurysm formation. The oculomotor nerve can be compressed or stretched by the expanding aneurysm, leading to symptoms such as ptosis, pupillary dilation, and extraocular muscle weakness. The oculomotor nerve is responsible for controlling eye movements, as well as pupil constriction and eyelid opening.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the Trochlear nerve (IV cranial nerve) is not typically involved in intracranial aneurysms.
* **Option B:** This option is incorrect because the Trigeminal nerve (V cranial nerve) is not typically involved in intracranial aneurysms, although it can be affected by other types of vascular malformations.
* **Option D:** This option is incorrect because the Abducens nerve (VI cranial nerve) is not typically involved in intracranial aneurysms.
**Clinical Pearl / High-Yield Fact**
The oculomotor nerve is often affected by aneurysms of the posterior communicating artery, and patients may present with a "diplopia, ptosis, and pupillary dilation" triad. This is a classic clinical correlation that students should remember.
**Correct Answer:** C.