Posterolateral tract
Encyclopedia
The posterolateral tract (fasciculus of Lissauer, Lissauer's tract, tract of Lissauer, dorsolateral fasciculus, zone of Lissauer) is a small strand situated in relation to the tip of the posterior column
close to the entrance of the posterior nerve roots.
. The second-order neurons ultimately synapse on neurons in the ventral posterior lateral nucleus
(VPL) of the thalamus
.
It consists of fine fibers which do not receive their myelin sheaths until toward the close of fetal life.
In addition it contains great numbers of fine non-myelinated fibers derived mostly from the dorsal roots but partly endogenous
in origin.
These fibers are intimately related to the substantia gelatinosa
which is probably the terminal nucleus.
The non-myelinated fibers ascend or descend for short distances not exceeding one or two segments, but most of them enter the substantia gelatinosa at or near the level of their origin.
The posterolateral spinal tracts are involved with neurological deficits seen in pernicious anemia
.
Heinrich Lissauer
(1861-1891).
Posterior column
thumb | right | Cross-section of the spinal cord Posterior column or dorsal column refers to the area of white matter in the dorsomedial side of the spinal cord. It is made up of the fasciculus gracilis and fasciculus cuneatus and itself is part of the dorsal funiculus...
close to the entrance of the posterior nerve roots.
Composition and Path
It contains centrally projecting axons carrying discriminative pain and temperature information (location, intensity and quality), which enter the spinal column ascend or descend one or two spinal segments in this tract before penetrating the grey matter of the dorsal horn where they synapse on second-order neurons. The axons of these second-order neurons cross the midline and ascend in the anterolateral quadrant of the contralateral half of the spinal cord, where they join the spinothalamic tractSpinothalamic tract
The spinothalamic tract is a sensory pathway originating in the spinal cord. It transmits information to the thalamus about pain, temperature, itch and crude touch...
. The second-order neurons ultimately synapse on neurons in the ventral posterior lateral nucleus
Ventral posterolateral nucleus
The ventral posterolateral nucleus is a nucleus of the thalamus. Together with the ventral posteromedial nucleus , VPI and VMpo, it constitutes the ventral posterior nucleus.-Input and output:...
(VPL) of the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
.
It consists of fine fibers which do not receive their myelin sheaths until toward the close of fetal life.
In addition it contains great numbers of fine non-myelinated fibers derived mostly from the dorsal roots but partly endogenous
Endogenous
Endogenous substances are those that originate from within an organism, tissue, or cell. Endogenous retroviruses are caused by ancient infections of germ cells in humans, mammals and other vertebrates...
in origin.
These fibers are intimately related to the substantia gelatinosa
Substantia gelatinosa
Substantia gelatinosa can refer to:* Substantia gelatinosa of Rolando * Substantia gelatinosa centralisSubstantia gelatinosa is a structure involved in pain transmission....
which is probably the terminal nucleus.
The non-myelinated fibers ascend or descend for short distances not exceeding one or two segments, but most of them enter the substantia gelatinosa at or near the level of their origin.
Clinical significance
During a complete occlusion of the ventral artery of the spinal cord, it is the only tract spared along with the dorsal columns.The posterolateral spinal tracts are involved with neurological deficits seen in pernicious anemia
Pernicious anemia
Pernicious anemia is one of many types of the larger family of megaloblastic anemias...
.
Eponym
The tract of Lissauer was named after German neurologistNeurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...
Heinrich Lissauer
Heinrich Lissauer
Heinrich Lissauer was a German neurologist who was born in Neidenburg . He studied at the Universities of Heidelberg, Berlin and Leipzig. He was a neurologist at the psychiatric hospital in Breslau, and was a one-time assistant to Carl Wernicke...
(1861-1891).
External links
- Overview at Cornell UniversityCornell UniversityCornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...