tract (trakt)

An extent of surface greater in length than in breadth, anterior cere bro pontine t. A t. of internal (mesial) fibers of the crus cerebri extending from the anterior part of the frontal lobe to the pons, anterior cortical t. Bundles of fibers from the cortex of the frontal lobe running to the ganglion cells of the pons Varolii, anterior fundamental t. The anterior fundamental fasciculi of the anterior column of the spinal cord. anterior pyramidal t. The longitudinal bundles of nerve fibers in the ventral half of the pons which represent the prolongation of the anterior pyramids of the medulla oblong at a. Bechterew's t. See tegmental t. bulbar t. central medullary t. The gray matter in the spinal cord which immediately surrounds the central canal. central vagus t. A t. of fibers pa ing from the layer of the fillet to the nucleus of the vagus of the opposite side. cerebellar t. See direct cerebellar t. cere bro pontine t. A t. of fibers starting from the brain cortex and pa ing through the internal capsule and the upper part of the cerebral peduncles to the pons, comma-shaped t. A t. shaped like a comma, observed in descending degeneration in the middle of the anterior third of the dorsal spinal cord. commi ural t. Of Owen, the cerebellar peduncles. communicating quint us t. A t. of fibers derived from the motor nucleus of the fifth nerve which at first surrounds the upper part of the sylvian aqueduct, and then widens, the fibers radiating through the tegmentum, and a portion of them curving around the lower border of the red nucleus as the fibrae arcuatae. This t. is brought into connection with the motor t's of fibers through the agency of intervening multipolar ganglion cells, cro ed thalamotegmental t. A t. of fibers connecting the thalamus with the spinal cord by way of the tegmentum, dendritic t's. T's of fibers that arise from all parts of the cerebral cortex, diverging from each other like the limbs of a tree, and pa into the white substance, digestive t. The alimentary canal, direct cerebellar t. A t. coursing in the lateral zone of the posterior half of the lateral column of the spinal cord, connecting the columns of Clarke with the cerebellum, which it enters as a component of the restiform column; called direct because it does not decu ate.