The fasciculus or the bundle of Vicq d'Azyr, ends with freely separated fibres within the nucleus anterior thalami.
The fasciculus the tegmental bundle of the corpus mamillare of Gudden, passes backward and enters the tegmentum of the cerebral peduncle. The major part of the fibres ends in a small ganglion, the ganglion profundum tegmenti, and in the neighboring gray substance of the Sylvian aqueduct, some fibres branching off to the posterior longitudinal fasciculus, while others are supposed to extend as far as the formatio reticularis of the pons.
The pedunculus corporis mamillaris has its origin within the lateral ganglion of the mammillary body. The bundle courses within the tegmentum and ends in the ganglion dorsale legmenli and in the surrounding gray substance. Fibres are also described as reaching the vicinity of the medial fillet. The dorsal longitudinal bundle of Schutz arises within the dorsal tegmental nucleus and the central gray substance (Fig. 139).
Concerning the course and destination of these bundles which pass from the corpus mamillare to the tegmental region, we are by no means sufficiently informed. According to other findings, also ascending bundles run within the pedunculus corporis mamillaris; these are said to arise within the tegmentum from the ganglion profundum, as well as from the fillet-layer, and to end within the corpus mamillare.
The dorsal longitudinal bundle of Schutz (KoBiker's dorsal gray longitudinal bun dle, Bechterew's dorsal longitudinal bundle of the central gray substance) is not to be confused with the strand commonly designated as the posterior longitudinal bundle. The longitudinal bundle of Schutz extends through the gray substance of the entire brain stem and is connected with the nuclei of all the cerebral nerves and many other ganglia. It is termed the fasciculus longitudinalis dorsalis, while the " posterior longitudinal bundle" is designated as the fasciculus longitudinalis medialis.
The majority of the fibres of the stria medullaris thalami end within the ganglion habenulae. The stria medullaris thalami conveys : a. Fibres coming from the fornix—tradus b. Fibres coming from the septum lucidum and from the area olfactoria—tractus c. Fibres coming from the interior of the thalamus—tractus
The fibres of the stria thalami which do not end within the ganglion habenulae traverse the latter and enter the commissura interhabenularis—a bundle of transverse fibres lying in front of the glandula pinealis. Some of these fibres end in the ganglion of the opposite side, others pass to the roof of the mid-brain, especially to the superior colliculus, while still others, perhaps, come into relation with the posterior longitudinal bundle.
Within the ganglion habenulae, the fasciculus retroflexus of Meynert takes its origin. This bundle ends within the substantia perforata posterior, in the region imme diately in front of the pons, in a small nucleus, the ganglion interpedunculare of Gudden. The bundle is called, therefore, also the tractus Within the ganglion interpedunculare arises the tegmental tract of the interpedun cular ganglion. The fibres pass dorsalward as far as the central gray to end partly in the ganglion tegmenti profundum and partly in the ganglion tegmenti dorsale and the surround ing central gray substance. Here joins, in turn, the dorsal longitudinal bundle of Schutz.
3. Connection of the primary centres of the two sides.—The fibres arise within the cortex of the tractus olfactorius and pass, forming the pars olfactoria of the anterior commissure, to the tractus of the opposite side. Here they end, partly within the granule-layer and. within the locality of the olfactory glonieruli of the bulbus.
4. Further connections of the primary fibres pass to the tuber cinereum, to the corpus mamillare, to the lower lying brain-segments and to the spinal cord. They form the olfactory radiation to the diencephalon and to the mid brain—tractus the basal olfactory bundle of Wallenberg.
The tract of fibres passing to the corpus mamillare is further joined by the fibre system of the mammillary body, whereby further relations with the thalamus and the mid-brain are established. A similar connection of the primary centres is effected through the fibre-system of the ganglion habenulae.