Fasciculus Longitudinalis Medialis


The oculomotor neurons were mostly labeled ipsilaterally and were located dorsomedially, abutting the Fasciculus longitudinalis medialis in the mesencephalon. The trochlear nucleus was located contralaterally and dorsolaterally adjacent to the Fasciculus longitudinalis medialis in the mesencephalon.  

Lesion of trigonum nervi hypoglossi, trigonum nervi vagi, colliculus facialis and Fasciculus longitudinalis medialis leads to severe disability or death of the patient..  

The first axons extended from the synencephalic tegmentum, forming the first fiber tract (Fasciculus longitudinalis medialis) in the ventral longitudinal zone of the neural rod, 38 hours after fertilization.  

We suggest that the mechanism for gaze paresis and loss of vestibulo-ocular reflex due to amitriptyline overdose involves the modulation of neurons of the pontine paramedian reticular formation, the rostral Fasciculus longitudinalis medialis, and the vestibulo-ocular reflex.  

In the forebrain, diencephalospinal projections originate in the ventral thalamus, posterior tubercle, the pretectal region, and the interstitial nucleus of the Fasciculus longitudinalis medialis.  

Throughout vertebrates including man, the Fasciculus longitudinalis medialis (flm) is the first descending pathway to be formed.  

In the interstitial nucleus of the Fasciculus longitudinalis medialis and various parts of the reticular formation - mesencephalic, pontine as well as medullary - DiI or BDA labelled neurons were observed. The earliest brainstem projections to the spinal cord all pass via the Fasciculus longitudinalis medialis..  

Fasciculus longitudinalis medialis (FLM) axons of much smaller caliber, among which MAs run in the ventral spinal cord, were also analyzed in two teleost fish belonging to continuously growing species.  

At maturity, an intense staining in the subsurface region could be found, due to the presence of large calibre fibres of the Fasciculus longitudinalis medialis.  

Sauvagine-immunoreactive (SVG-ir) bipolar neurons were found in the nucleus of the Fasciculus longitudinalis medialis located in the rostral mesencephalic tegmentum.  

Their dendritic arborizations extend profusely in the ipsilateral tegmentum and reach the oculomotor nucleus, the Fasciculus longitudinalis medialis and also small processes branch towards the ventricle.  

interpeduncularis dorsalis, the nucleus of the Fasciculus longitudinalis medialis, the nucleus and the nucleus interstitialis of flm, the n.  

A major descending projection originated from the griseum centrale (including the nucleus laminaris of the torus semicircularis), while minor areas of origin, apart from isolated reticular cells, were the nucleus and the interstitial nucleus of the Fasciculus longitudinalis medialis, the red nucleus, the locus coeruleus and the raphe nuclei.  

The preoculomotor centers, which are connected by the Fasciculus longitudinalis medialis in the brain stem, are deemed to be the common focus for progressive scoliosis and associated visual dysfunction..  

A small rhombencephalic group is located rostrolateral to the efferent octaval nucleus, between the Fasciculus longitudinalis medialis and the decussation of the lateral lemniscus.  

Since the MA cytoskeletal composition is not known in the adult fish, the MA cytoskeletal composition has been compared to other axons of much smaller diameter of the Fasciculus longitudinalis medialis (flm) among which the MA run in the ventral spinal cord.  

The Mauthner axon originates from the Mauthner cell in the medulla and runs in the Fasciculus longitudinalis medialis in the spinal cord.  

In the brainstem VIP immunoreactive fibers and terminals were observed mainly in the substantia grisea centralis, Fasciculus longitudinalis medialis, lemniscus lateralis, and in the area surrounding the nuclei of the 7th, 9th, and 10th cranial nerves.  

In recovered salamanders examined 8 and 12 weeks post-transection, HRP-labeled neurons were found in the red nucleus, in the interstitial nucleus of the Fasciculus longitudinalis medialis, and in the mesencephalic as well as the medullary reticular neurons.  

In the adult lizard, GFAP-positive radial glia are still present and coexist with GFAP-positive astrocytes, which are prefentially located in the marginal optic tract and the oculomotor nuclei, but are absent in the Fasciculus longitudinalis medialis.  

Weaklyimmunoreactive perikarya were found medially to the nucleus diffusus tori lateralis and in the rostral rhombencephalon, laterally to the Fasciculus longitudinalis medialis, and dorsally to the fasciculus longitudinalis lateralis.  

At this level numerous IR cell bodies were detected around the Fasciculus longitudinalis medialis (FLM).  

Fusiform cells in the medullary Fasciculus longitudinalis medialis filled with FB but not HRP.  

In addition, each motoneuron has a ventral dendrite that extends towards the Fasciculus longitudinalis medialis and to the ventral tegmentum.  

The neurons are located in the rhombencephalon in two distinct groups which lie dorsolateral and lateral to the Fasciculus longitudinalis medialis and represent the main and accessory abducens nuclei, respectively.  

A small number of ChAT-IR neurons, located on the dorsal aspect of the Fasciculus longitudinalis medialis (caudal to n.  

of the Fasciculus longitudinalis medialis, nucl.  

The former two cell groups sent their axons to the Fasciculus longitudinalis medialis. The axons of these cell groups joined the Fasciculus longitudinalis medialis and the "tractus bulbospinalis." The Mauthner cell had two main gigantic dendrites, and its giant axons formed a conspicuous fiber of Mauthner throughout the rhombencephalon down to the spinal cord. The axons of the nucleus vestibularis magnocellularis and nucleus intermedius entered the Fasciculus longitudinalis medialis and/or the tractus bulbospinalis.  

Extensive brainstem projections directed to cervical and high thoracic spinal levels originate from the area lateralis hypothalami, the nucleus of the Fasciculus longitudinalis medialis, the contralateral nucleus cerebellaris medialis, and from the nucleus tractus solitarii.  

Efferents of lobe C1 have been found to arise from a peculiar cell type in the Purkinje cell layer (so-called eurydendroid neurons) and to project predominantly to the nucleus of the Fasciculus longitudinalis medialis, the nucleus reticularis superius and medius, and the trigeminal motor nucleus.  

Large accumulations of grains were seen in the hypothalamus, the amygdala, in the fasciculus medialis prosencephali, in the Fasciculus longitudinalis medialis, in the ventrolateral part of the periventricular gray matter, in the lemniscus medialis and in the raphe nuclei.  

Ascending projections crossing the midline in the ventral isthmomesencephalic tegmentum terminated in the contralateral red nucleus and nuclei of the Fasciculus longitudinalis medialis (f lm). Spinal projections coursing within the ipsilateral ventral descending tract and the ipsilateral Fasciculus longitudinalis medialis were found to arise from both rostral and caudal vestibular regions. The caudal vestibular nuclear complex in addition gave rise to fibers descending in the contralateral Fasciculus longitudinalis medialis.  

MA (50 ng per rat) microinjected into neighbouring sites, the nucleus reticularis parvocellularis, the nucleus originis nervi abducentis and the Fasciculus longitudinalis medialis, elicited no significant effect.  

substantia nigra pars lateralis, interpeduncular nucleus, inferior colliculus, nucleus cuneiformis, dorsal tegmental nucleus of Gudden, nucleus laterodorsalis tegmenti, nucleus vestibularis medialis, nucleus vestibularis inferioris, in the Fasciculus longitudinalis medialis and nucleus parvocellularis compacta.  

tegmenti pedunculo-pontinus pars compacta and bilateral: zona peri-Fasciculus longitudinalis medialis, substantia grisea centralis, n.  

In the present study the vestibular components of the Fasciculus longitudinalis medialis (flm) were investigated in the lizard Varanus exanthematicus with various tracing techniques: anterograde transport of horseradish peroxidase to study vestibulo-oculomotor and vestibulospinal projections, the multiple retrograde fluorescent tracer technique for the cells of origin of such projections.  

With anterograde tracing techniques (3H-leucine and HRP) this tract was found to terminate in the nucleus ruber and the interstitial nucleus of the Fasciculus longitudinalis medialis.  

Tyrosine hydroxylase-immunoreactive terminal areas in the brain stem were seen in the nucleus interstitialis of the Fasciculus longitudinalis medialis, the nucleus raphes superior, the locus coeruleus, several parts of the reticular formation and the nucleus descendens nervi trigemini.  

Besides DA cells of SN and its extensions, DA cells were also observed more caudally in nucleus raphe linearis intermedius and dorsalis, decussation of brachium conjunctivum, Fasciculus longitudinalis medialis and periaqueductal gray.  

At stage 30/31 (the tailbud is visible) both Mauthner cells project to the spinal cord as well as the interstitial nucleus of the Fasciculus longitudinalis medialis situated in the mesencephalon. However, the interstitial nucleus of the Fasciculus longitudinalis medialis forms an exception to this rule..  

Injections involving the granular layer resulted in labelling in the ventral horn of the cervical spinal cord, the caudal spinal trigeminal nucleus, the nucleus caudalis and the medial portion of the nucleus ventralis of the vestibular nerve, the inferior reticular nucleus and the nucleus of the Fasciculus longitudinalis medialis.  

reticularis magnus, periventricular grey matter, bed nucleus of the Fasciculus longitudinalis medialis and in the nu.  

Afferent projections to the vestibular nuclei were found to arise in the nucleus of the basal optic root, the interstitial nucleus of the Fasciculus longitudinalis medialis, the medial and lateral cerebellar nuclei, the perihypoglossal nuclear complex, and the reticular formation. These projections appeared to be directed to the interstitial nucleus of the Fasciculus longitudinalis medialis, the oculomotor, trochlear, and abducens nuclei.  

As well as from the main motor pools with which they are associated, the medial rectus, inferior rectus, superior rectus, levator palpebrae, superior oblique and lateral rectus muscles all receive innervation from motoneurons lying among the fibres of the Fasciculus longitudinalis medialis.  

The ventral tegmental nucleus of Gudden is composed of oval or polygonal, medium-sized, well-stained cells, and includes the pars principalis situated ventral to the Fasciculus longitudinalis medialis, and the pars suprafascicularis in the central gray matter dorsal to the Fasciculus longitudinalis medialis (in the golden hamster, mouse, vole, and house shrew). In the cat, dog, rat, gerbil, and rabbit, the isthmus stands at the dorsal edge of the Fasciculus longitudinalis medialis; in the golden hamster, mouse, vole, and house shrew, within the central gray matter; and in the guinea pig, at the ventral edge of the Fasciculus longitudinalis medialis.  

Additional neurons were found in the periventricular hypothalamus, the nucleus of the Fasciculus longitudinalis medialis and in the n.interstitialis of flm on both sides as well as in the red nucleus..  

At the level of the isthmus, numerous immunoreactive cell bodies were located medially between the fiber bundles of the Fasciculus longitudinalis medialis.  

tangentialis); from the motor trigeminal nucleus; from the contralateral red nucleus, the ipsilateral nucleus (n.) interstitialis of the Fasciculus longitudinalis medialis (flm) and from the hypothalamus.  

A considerable number of IA cells (13,600, representing 23% of the total) were found in locations outside the raphe nuclei: in ventral brainstem as lateral extensions from the raphe, among the bundles of Fasciculus longitudinalis medialis, in periventricular gray and adjacent tegmentum, mixing with the noradrenergic cells of the locus coeruleus complex, among the mesencephalic dopamine cells, and in the nucleus interpeduncularis..  

Projections to the cerebellum were demonstrated from the nucleus of the basal optic root, the interstitial nucleus of the Fasciculus longitudinalis medialis, the vestibular ganglion, and the vestibular nuclear complex, two somatosensory nuclei, viz., the descending nucleus of the trigeminal nerve and the nucleus of the dorsal funiculus, the nucleus of the solitary tract, the reticular formation, and throughout the spinal cord.  

In stage 50, cells of origin of descending supraspinal pathways were already present throughout the reticular formation (including the interstitial nucleus of the Fasciculus longitudinalis medialis) and in the vestibular nuclear complex.  

In the goldfish, efferent labyrinthine neurons could be demonstrated in a medial position (lateral to the Fasciculus longitudinalis medialis).  

Descending pathways from mesencephalic structures originate from the interstitial nucleus of the Fasciculus longitudinalis medialis, the tectum mesencephali, the nucleus intercollicularis, the tectotegmental junction zone, and from diffusely arranged tegmental neurons.  

At more rostral levels the labeled cells are in the nucleus of the Fasciculus longitudinalis medialis, in the nucleus interstitialis of the Fasciculus longitudinalis medialis, in the contralateral red nucleus, in lamina six of the contralateral optic tectum, bilaterally in the nucleus of the posterior commissure and in the mesencephalic nucleus in the Vth nerve. Injections in the lumbar cord label neurons of the nucleus posteroventralis tegmenti mesencephali (Potter) and nucleus interstitialis of the Fasciculus longitudinalis medialis. Nuclei that had not been previously identified in anurans but which were labeled after HRP spinal injections (i.e., the nucleus interstitialis of the Fasciculus longitudinalis medialis, the nucleus of the posterior commissure and the red nucleus) have been delimited in normal material in Nissl-stained transverse sections.  

Histoenzymological study of acid phosphatase (GP-AI), 5-nucleotidase (AMP-A), adenosine triphosphatase (ATP-A) and beta-galactosidase (GLAC-A) of the metencephalon of turtle shows a pattern of distribution of enzymes similar to amphibians and mammalian metencephalon which provides indication of homology of the nuclei and tracts such as nucleus raphe, nuclei cerebelli Fasciculus longitudinalis medialis, commissura ansulata and internal arcuate fibers.  

laterodorsalis tegmenti, (4) parabrachial area, (5) A1, A2, A4, A5 and A7 areas where noradrenaline-containing neurons were disseminated, (6) A8, A9 and A10 areas which contain dopamine neurons, (7) surrounding area of the Fasciculus longitudinalis medialis at the level of the n.  

Medially, in the same region a nucleus of serotonergic neurones lies between the paired tracts of the Fasciculus longitudinalis medialis.  

Furthermore, the present study indicated that there were direct projections to the anterior hypothalamus from non-noradrenergic neurons in the lower brain stem: nuclei raphe dorsalis, centralis superior, cells in the mesencephalic and pontine central gray matter, nuclei parabrachialis lateralis and medialis, cells around Fasciculus longitudinalis medialis..  

The nucleus interstitialis of the Fasciculus longitudinalis medialis is remarkably developed and consists of large neurons.  

Acute lesion experiments indicated that signals for this excitation reached IIIrd and IVth nuclei via three different pathways; from the anterior canal through the ipsilateral brachium conjunctivum, from the horizontal canal through the ipsilateral Fasciculus longitudinalis medialis and from the posterior canal through the contralateral Fasciculus longitudinalis medialis..  


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