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Grey matter, or gray matter in American English, is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.
Bundles of fibers are known as nerve tracts, and consist of association tracts, commissural tracts, and projection tracts. The association fibers unite different parts of the same cerebral hemisphere , and are of two kinds: (1) short association fibers that connect adjacent gyri; (2) long association fibers that make connections between more ...
It is a region formed by several grey matter nuclei and their associated white matter structures, namely: [3] The subthalamic nucleus, whose neurons contain glutamate and have excitatory effects over neurons of globus pallidus and substantia nigra; Zona incerta, located between fields of Forel H 1 and H 2.
Gray matter (which is only gray in preserved tissue, and is better described as pink or light brown in living tissue) contains a high proportion of cell bodies of neurons. White matter is composed mainly of myelinated axons, and takes its color from the myelin. White matter includes all of the nerves, and much of the interior of the brain and ...
The corpus callosum is the largest commissural tract in the human brain. It consists of about 200–300 million axons that connect the two cerebral hemispheres. The corpus callosum is essential to the communication between the two hemispheres.
The cerebellum consists of an inner medulla of white matter and an outer cortex of richly folded grey matter. [35] The cerebellum's anterior and posterior lobes appear to play a role in the coordination and smoothing of complex motor movements, and the flocculonodular lobe in the maintenance of balance [ 36 ] although debate exists as to its ...
The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem. There are three groupings of neurons that are involved in the pathway: first-order neurons, second-order neurons, and third-order neurons.
The pyramidal tracts include both the corticobulbar tract and the corticospinal tract.These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar) or spinal cord (corticospinal) and are involved in the control of motor functions of the body.