Herniation of the uncus results in compression of which cranial nerve?

Herniation of the uncus refers to a condition where part of the temporal lobe, specifically the uncus, is displaced downward due to increased intracranial pressure. This herniation can lead to compression of the third cranial nerve, also known as the oculomotor nerve.

The third cranial nerve is responsible for controlling most of the eye’s movements, as well as regulating the size of the pupil and maintaining an open eyelid. When the uncus herniates, it can exert pressure on this nerve, leading to symptoms such as ptosis (drooping eyelid), mydriasis (dilated pupil), and impaired eye movement. Recognizing these symptoms is crucial in clinical settings as they indicate a potentially life-threatening condition requiring immediate medical attention.

In contrast, the first cranial nerve (olfactory) primarily deals with the sense of smell and is not typically affected by uncus herniation. The eighth cranial nerve (vestibulocochlear) is involved in hearing and balance, while the twelfth cranial nerve (hypoglossal) controls tongue movements. These cranial nerves are located in areas that are not as directly threatened by uncus herniation, hence they