Neuroanatomy, Brainstem

The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum. It is composed of three sections in descending order: the midbrain, pons, and medulla oblongata. It is responsible for many vital functions of life, such as breathing, consciousness, blood pressure, heart rate, and sleep. The brainstem contains many critical collections of white and grey matter. The grey matter within the brainstem consists of nerve cell bodies and forms many important brainstem nuclei. The white matter tracts of the brainstem include axons of nerves traversing their course to different structures; the axons originate from cell bodies located elsewhere within the central nervous system (CNS). Some of the white matter tract cell bodies are located within the brainstem as well. These tracts travel both to the brain (afferent) and from the brain (efferent), such as the somatosensory pathways and the corticospinal tracts, respectively. Ten of the twelve cranial nerves arise from their cranial nerve nuclei in the brainstem. Clinicians can localize lesions of the brainstem with a thorough knowledge of brainstem anatomy and functions. The following activity addresses the nuclei, tracts, and functions of the brainstem.