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Medial lemniscus

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Brain: Medial lemniscus
Gray759
The sensory tract. (Medial lemniscus labeled at center right.)
Gray710
Coronal section through mid-brain. ("e" is Portion of medial lemniscus, which runs to the lentiform nucleus and insula.)
Latin lemniscus medialis
Gray's subject #188 803
Part of
Components
Artery
Vein
BrainInfo/UW ancil-736
MeSH [1]

The medial lemniscus, also known as Reil's band or Reil's ribbon, is a pathway in the brainstem that carries sensory information from the gracile and cuneate nuclei to the thalamus. It forms part og the lemniscal system

The term applies to one of two bundles of nerve fibers of the lemniscus which ascend through the medulla oblongata and pons and go on up to the somatosensory cortex in each hemisphere[1].

PathEdit

After neurons carrying proprioceptive or touch information synapse at the gracile and cuneate nuclei, axons from secondary neurons decussate at the level of the medulla and travel up the brainstem as the medial lemniscus on the contralateral (opposite) side. It is part of the posterior column-medial lemniscus system, which transmits touch, vibration sense, as well as the pathway for proprioception.

The medial lemniscus axons from most of the body synapse at the ventral posterolateral nucleus of the thalamus. The axons transmitting information from the trigeminal nerve synapse at the ventral posteromedial nucleus of the thalamus.

Location of the medial lemniscus through the brainstemEdit

  • The cuneate and gracile nuclei reside at the closed (lower) medulla, so the lemniscus isn't formed at this level. Fibres from these nuclei will pass to the contralateral side of the brainstem, as the internal arcuate fibres.
  • At the open medulla (further up the brainstem), the medial lemniscus contains axons from the trigeminal nerve (which supplies the head region), as well as the arms and legs. It sits very close to the midline, at the same orientation of the midline, with head fibres more dorsal (closer to the back), towards the fourth ventricle.
  • By mid-pons, the medial lemniscus has rotated. Fibres from the head are medial, fibres from the leg are lateral.
  • The orientation in the midbrain is similar to that in the pons.

See alsoEdit

Additional imagesEdit

ReferencesEdit

  1. Coleman,A F (2006). Oxford Dictionary of Psychology, 2nd ed. Oxford:OUP.

External linksEdit



Mesencephalon (midbrain)

cerebral peduncle: midbrain tegmentum (periaqueductal gray, ventral tegmentum, nucleus raphe dorsalis), pretectum, substantia nigra, red nucleus, pedunculopontine nucleus, medial longitudinal fasciculus, medial lemniscus, rubrospinal tract, lateral lemniscus

tectum: corpora quadrigemina, inferior colliculi, superior colliculi

cerebral aqueduct: oculomotor nucleus, trochlear nucleus, Edinger-Westphal nucleus

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