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 Posterior may refer to: * Posterior (anatomy), the end of an organism opposite to its head ** Buttocks, as a euphemism * Posterior horn (disambiguation) * Posterior probability, the conditional probability that is assigned when the relevant evidenc ...

close to the entrance of the

posterior nerve roots The dorsal root of spinal nerve (or posterior root of spinal nerve or sensory root) is one of two "roots" which emerge from the spinal cord. It emerges directly from the spinal cord, and travels to the dorsal root ganglion. Nerve fibres with the v ...

. It is present throughout the spinal cord, and is most developed in the upper cervical regions.

Structure

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 in either the

substantia gelatinosa of Rolando The apex of the posterior grey column, one of the three grey columns of the spinal cord, is capped by a V-shaped or crescentic mass of translucent, gelatinous neuroglia, termed the substantia gelatinosa of Rolando (or SGR) (or gelatinous substanc ...

or the

nucleus proprius The nucleus proprius is a layer of the spinal cord adjacent to the substantia gelatinosa. The nucleus proprius can be found in the gray matter in all levels of the spinal cord. It constitutes the first synapse of the spinothalamic tract carrying pa ...

. Those neurons project their axon to the anterolateral quadrant of the contralateral half of the spinal cord, where they give the

spinothalamic tract The spinothalamic tract is a part of the anterolateral system or the ventrolateral system, a sensory pathway to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cor ...

. The axons of second-order neurons ultimately synapse on neurons in the ventral posterior lateral nucleus (VPL) of the

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...

after coursing in the spinal lemniscus. After this, the 3rd order neuron fibers traverse the internal capsule and the corona radiata, ultimately synapsing in the post central gyrus (somatosensory cortex). The location of this synapse is dependent upon the somatotopic organisation of the somatosensory cortex, it can be estimated according to the position on the 'somatosensory homunculus' The posterolateral tract consists of fine fibers which do not receive their myelin sheaths until toward the close of

fetal A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal develo ...

life. In addition it contains great numbers of fine non-myelinated fibers derived mostly from the

dorsal roots The dorsal root of spinal nerve (or posterior root of spinal nerve or sensory root) is one of two "roots" which emerge from the spinal cord. It emerges directly from the spinal cord, and travels to the dorsal root ganglion. Nerve fibres with the ve ...

but partly

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, es ...

in origin. These fibers are intimately related to the

substantia gelatinosa The apex of the posterior grey column, one of the three grey columns of the spinal cord, is capped by a V-shaped or crescentic mass of translucent, gelatinous neuroglia, termed the substantia gelatinosa of Rolando (or SGR) (or gelatinous substanc ...

which is probably their 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 In human anatomy, the anterior spinal artery is the artery that supplies the anterior portion of the spinal cord. It arises from branches of the vertebral arteries and courses along the anterior aspect of the spinal cord. It is reinforced by sever ...

, it is the only tract spared along with the

dorsal column Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

s. The posterolateral spinal tracts are involved with neurological deficits seen in

pernicious anemia Pernicious anemia is a type of vitamin B12 deficiency anemia, a disease in which not enough red blood cells are produced due to the malabsorption of vitamin B12. Malabsorption in pernicious anemia results from the lack or loss of intrinsic fa ...

Eponym

The ''tract of Lissauer'' was named after German

neurologist Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal c ...

Heinrich Lissauer Heinrich Lissauer (12 September 1861 – 21 September 1891) was a German neurologist born in Neidenburg (today Nidzica, Poland). He was the son of archaeologist Abraham Lissauer (1832-1908). He studied at the Universities of Heidelberg, Berli ...

(1861-1891).

References

External links

*
Overview
at

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to teach an ...

{{Authority control Spinal cord tracts