corticospinal tract

a major motor pathway that originates in the cerebral cortex (see motor cortex), passes through the pyramid of the medulla oblongata, and descends to terminate in the spinal cord. At the pyramid, most of its fibers cross over to form the lateral corticospinal tract; the remaining fibers, forming the smaller anterior corticospinal tract, descend anteriorly in the white matter of the spinal cord to terminate in the anterior horns. See also pyramidal tract.

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Psychology term of the day

November 16th 2024

simple eye

the type of eye found in most vertebrates and some invertebrates. It consists of a single focusing element, which may be a thickening of the exoskeleton (in an arthropod), a pinhole in the surface of the eye (in a mollusk), or a crystalline lens (in a vertebrate), plus one or more photosensitive cells. Compare compound eye.