Stria medullaris

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 the 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.