Mammillothalamic tract

The mammillothalamic tract (also mammillary fasciculus, mammillothalamic fasciculus, thalamomammillary fasciculus, bundle of Vicq d'Azyr) is an efferent pathway of the mammillary body which projects to the anterior nuclei of thalamus. It consists of heavily myelinated fibres. It is part of a brain circuit involved in spatial memory.

It arises from (the medial and lateral nuclei of) the mammillary body and from fibers that are directly continued from the fornix. It connects the mammillary body to the dorsal tegmental nuclei, the ventral tegmental nuclei, and the anterior thalamic nuclei.

Structure
Axons divide within the gray matter; the thicker fibres form the MTT while the finer branches descend as the mammillotegmental fasciculus. The MTT spreads fan-like as it terminates in the medial dorsal nucleus. Some fibers pass through the dorsal nucleus to the angular nucleus of the thalamus. (a group of cells ventral to the lateral dorsal nucleus of thalamus ). The axons from these nuclei form part of the thalamocortical radiations.

Clinical significance
Infarction of the region including the mammillothalamic tract has been associated with alcoholic Korsakoff syndrome.

History
The mammillothalamic tract was first described by the French physician, Félix Vicq d'Azyr, from whom it takes its alternate name (bundle of Vicq d'Azyr).