The trigeminal nerve: an illustrated review of its imaging anatomy and pathology.

The trigeminal nerve is the largest cranial nerve and has both sensory and motor components. Due to its extensive distribution in the head and neck, the nerve or its branches may be involved by a myriad of disease entities. Additionally, the nerve may act as a route of spread in various inflammatory and neoplastic diseases, underlining the need for a thorough understanding of its anatomy. A segmental division of the trigeminal system is preferred when interpreting imaging studies as both the type of lesion and symptoms may vary based on the site of involvement. These segments include the brainstem, cisternal, Meckel's cave, cavernous sinus, and peripheral divisions. In general, dedicated magnetic resonance imaging (MRI) is preferred to evaluate nerve dysfunction. In select cases, contrast medium administration, heavily T2-weighted sequences, or MR angiography may prove to be diagnostic. This review aims to review the anatomy of the trigeminal nerve briefly, followed by illustrations of various lesions that may present with trigeminal nerve dysfunction.