NeuroLex ID Lissauers tract FMA 72616 | TA A14.1.02.228 | |
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The posterolateral tract (fasciculus of Lissauer, Lissauer's tract, tract of Lissauer, dorsolateral fasciculus, dorsolateral tract, 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. It is present throughout the spinal cord, and is most developed in the upper cervical regions.
Contents
Composition and Path
The posterolateral tract contains centrally projecting axons from dorsal root ganglion cells carrying crude touch and pressure information (location, intensity and quality). These axons enter the spinal column and penetrate the grey matter of the dorsal horn, where they synapse on second-order neurons. After ascending or descending in the anterolateral quadrant of the contralateral half of the spinal cord, where they join the spinothalamic tract. The second-order neurons ultimately synapse on neurons in the ventral posterior lateral nucleus (VPL) of the thalamus after passing through the medial leminiscus. After this, the nerves pass through the internal capsule, to the corona radiate, ultimately synapsing in the post central gyrus (somatosensory cortex). The location of this synapse is dependent upon the somatotopical organisation of the somatosensory cortex, it can be estimated according to the position on the 'somatosensory homunculus'
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.
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.
Eponym
The tract of Lissauer was named after German neurologist Heinrich Lissauer (1861-1891).