Stria medullaris of thalamus

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Stria medullaris of thalamus
Grays Stria Medullaris.jpg
Stria medullaris highlighted in red over the thalamus. Posterior to the thalamus, the highlighted portion is the pineal gland
Details
Identifiers
Latin stria medullaris thalamica
NeuroNames 298
NeuroLex ID birnlex_1066
TA98 A14.1.08.106
TA2 5747
FMA 62080
Anatomical terms of neuroanatomy

The stria medullaris (SM), (Latin, furrow and pith or marrow) is a part of the epithalamus and forms a bilateral white matter tract of the initial segment of the dorsal diencephalic conduction system (DDCS). It contains afferent fibers from the septal nuclei, lateral preoptico-hypothalamic region, and anterior thalamic nuclei to the habenula. It forms a horizontal ridge on the medial surface of the thalamus on the border between dorsal and medial surfaces of thalamus. The SM, in conjunction with the habenula and the habenular commissure, forms the habenular trigone. It is considered to be the primary afferent of the DDCS.

Contents

History

Vesalius showed it in his 1543 De Humani Corporis Fabrica Libri Septem. It first received its present name from Wenzel and Wenzel in 1812. The SM can be referred to as the stria medullaris thalami or habenular stria. Historically it has also been called the columna medullaris, markiger Streisen and rené. It was once thought to be part of the olfactory system.

Anatomy

The SM emerges as a bilateral compact fascicle just posterior to the anterior commissure, where it converges with the fornix and stria terminalis. As it courses caudally along the third ventricle's roof, it attaches to the tela chordae and arches dorsally over the thalamus. In the majority of individuals, it arches superior to the interthalamic adhesion. The SM then descends caudally, with its lateral fibers terminating in the habenula. The medial SM fibers, on the other hand, flex inwards towards the pineal gland's base, crossing to the opposite side and terminating in the contralateral habenula. This crossing is known as the habenular commissure.

Function

The SM primarily gathers fibers from various brain regions, including the frontal, septal, striatal, and hypothalamic areas, and conveys information to the lateral and medial habenulae. It operates in a predominantly unidirectional manner, transmitting input from forebrain regions to the habenula. The SM's afferents are primarily cholinergic, glutamatergic, and GABAergic. Bilateral transection of the SM in rodents causes decreases of enzymes in the habenulae, indicating functional importance there.

Clinical significance

The SM, in conjunction with the habenula, has been identified as a potential therapeutic target for deep brain stimulation in the treatment of intractable depression. Preliminary results suggest significant improvement with modulation of the DDCS through SM stimulation. Given the intertwined nature of the SM and habenula, it is challenging to define a function for the SM independent of the habenula.

Sources

Related Research Articles

Articles related to anatomy include:

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<span class="mw-page-title-main">Habenula</span>

The habenula is a small bilateral neuronal structure in the brain of vertebrates, that has also been called a microstructure since it is no bigger than a pea. The naming as little rein describes its elongated shape in the epithalamus, where it borders the third ventricle, and lies in front of the pineal gland.

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The fasciculus retroflexus (FR) also known as the habenulointerpeduncular tract is a bundle of fibers located at the base of the midbrain in vertebrates. Connected to the habenula (Hbn) and the interpeduncular nucleus (IPN), the fasciculus retroflexus is involved in a variety of bodily phenomena, some being sleep retention. and drug addiction. It acts as a channel through which messages are sent between the stria medullaris and the mid- and hindbrain. The fasciculus retroflexus, along with the stria medullaris, the habenula, and the medial forebrain bundle forms a unit for the transfer of neurological impulses. In this unit, the fasciculus retroflexus mediates the transfer of information for processes such as pain, pleasure, and motor control

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