medial lemniscus(redirected from Lemniscus medialis)
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a band of white fibers originating from the gracile and cuneate nuclei and decussating in the lower medulla; thence it passes upward through the center of the medulla oblongata, close to the median raphe; on entering the pons it spreads out laterally to form a flat band ascending over the superior border of the pontine nuclei; in the mesencephalon it passes over the superior border of the substantia nigra and is displaced laterally by the red nucleus; passing medial to the medial geniculate body, the bundle enters and terminates in the ventral posterior nucleus of the thalamus. Throughout their course, the fibers retain a somatotopic order such that those originating from the gracile nucleus and representing the lower extremity lie lateral to those originating in the cuneate nucleus and representing the arm. The medial lemniscus conveys somatic-sensory information involved in tactile discrimination (2-point discrimination), position sense, and vibration sense.
An axon tract originating in the cuneate and gracile nuclei, at the junction between the spinal cord and brainstem, and ascending to the ventral posterior nucleus of the thalamus. This lemniscus is a middle link in the circuit carrying somatic sensory information from the body to the primary sensory cortex.
See also: lemniscus
Reil,Johann C., German physician, neurologist, and histologist, 1759-1813.
circular sulcus of Reil - a semicircular fissure. Synonym(s): circular sulcus of insula; limiting sulcus of Reil
island of Reil - an oval region of the cerebral cortex overlying the extreme capsule, lateral to the lenticular nucleus, buried in the depth of the fissura lateralis cerebri (sylvian fissure). Synonym(s): insula; insular area; insular cortex
limiting sulcus of Reil - Synonym(s): circular sulcus of Reil
Reil ansa - a complex fiber bundle. Synonym(s): ansa peduncularis
Reil band - Synonym(s): medial lemniscus; septomarginal trabecula
Reil ribbon - Synonym(s): medial lemniscus
Reil triangle - Synonym(s): lemniscal trigone