Stria medullaris thalami
A slender band of white fibres along the upper medial edge of the thalamus, running back to the habenula in the epithalamus.
At a glance
- English
- Stria medullaris thalami
- Latin (TA2)
- Stria medullaris thalami
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the stria medullaris thalami
The stria medullaris thalami is a narrow bundle of nerve fibres that belongs to the epithalamus. It runs from front to back along the border between the upper and medial surfaces of each thalamus, where it raises a low horizontal ridge in the wall of the third ventricle. The thin roof of the ventricle, the tela choroidea with its ependyma, is attached along a line just above it, the taenia thalami, so the stria marks the upper edge of the ventricular wall.
At its back end the stria widens into the habenular trigone, a small triangular area in front of the superior colliculus that contains the habenular nuclei. Some of its fibres end there on the same side; others cross the midline in the habenular commissure, in the upper lamina of the pineal stalk, to reach the habenula of the other side.
The stria is the main input route to the habenula. Its fibres come from the septal nuclei, the lateral preoptic and lateral hypothalamic regions, the anterior thalamic nuclei, the globus pallidus and the region of the anterior perforated substance. In this way the limbic forebrain and basal ganglia reach the habenula, which then projects through the habenulointerpeduncular tract (fasciculus retroflexus) to the interpeduncular nucleus and to the dopamine and serotonin cell groups of the midbrain. The pathway as a whole helps signal disappointment and expected punishment and so dampens behaviour that has gone unrewarded.
Overactivity of the habenula has been linked with depression in imaging and animal studies, and deep brain stimulation of the habenular region has been tried in severe cases. The stria should not be confused with the striae medullares of the fourth ventricle, which are separate fibres crossing the floor of that ventricle.
Function and supply
- Function
- Carries fibres from the septal area, hypothalamus, anterior thalamus and pallidum to the habenular nuclei, part of a circuit that tempers behaviour after unexpected loss of reward.
- Blood supply
- Posterior medial choroidal branches of the posterior cerebral artery.
Anthromica
See the stria medullaris thalami where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
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