the gray matter of the habenula, composed of a small-celled medial habenular nucleus [TA] (nucleus habenularis medialis [TA]) and a large-celled lateral habenular nucleus [TA] (nucleus habenularis lateralis [TA]); both nuclei receive fibers from basal forebrain regions (septum, basal nucleus, lateral preoptic nucleus); the lateral habenular nucleus receives an additional projection from the medial segment of the globus pallidus. Both nuclei project by way of the retroflex fasciculus to the interpeduncular nucleus and a medial zone of the midbrain tegmentum. SYN: ganglion habenulae.
