MR imaging of the excised human brainstem: a correlative neuroanatomic study.

The purpose of this study was to examine an excised human brainstem with high-resolution MR imaging. The MR images were correlated with myelin-stained histologic specimens and standard anatomic descriptions. Structures visualized included nuclei and/or fibers of all the cranial nerves, with the exception of the trochlear nerve. The topography of the brainstem is discussed. Major tracts such as the corticospinal spinothalamic, spinocerebellar, medial and lateral lemniscus, and other ascending and descending tracts and intrinsic brainstem nuclei such as the olivary complex, pontine nuclei, red nucleus, and inferior and superior colliculi were identified. Functional neuroanatomy of the brainstem is reviewed. This neuroanatomic description and review of the complex MR anatomy of the brainstem should assist in the delineation of brainstem structures on MR imaging.