Paramedian reticular nucleus
Encyclopedia
The paramedian reticular nucleus (in Terminologia Anatomica
, or paramedian medullary reticular group in NeuroNames
) sends its connections to the spinal cord in a mostly ipsilateral manner, although there is some decussation.
It projects to the vermis in the anterior lobe, the pyramis and the uvula
.
The paramedian nucleus also projects to the contralateral PRN, the gigantocellular nucleus
, and the nucleus ambiguous.
The paramedian reticular formation is adjacent to the abducens (VI)nucleus in the pons and adjacent to the oculomotor nucleus(III) in the midbrain.
The paramedian nucleus receives afferents mostly from the fastigial nucleus
in the cerebellum and the cerebral cortex; however, the projections from the spinal cord are very sparse.
The descending afferent connections come mostly from the frontal and parietal lobes; however the pontine reticular formation also sends projections to the paramedian reticular nucleus.
There are also very sparse innervations from the superior colliculus
.
Lesions in the paramedian reticular nucleus have been shown to cause a stereotyped increase in the random patterns of motion in rats. The paramedian nuclei on either side of the brain stem have been shown to mediate the horizontal eye movements on their ipsilateral sides. It seems possible that the random motion patterns of the above rats were caused by an inability to mediate their horizontal eye movements.
Terminologia Anatomica
Terminologia Anatomica is the international standard on human anatomic terminology. It was developed by the Federative Committee on Anatomical Terminology and the International Federation of Associations of Anatomists and was released in 1998. It supersedes the previous standard, Nomina...
, or paramedian medullary reticular group in NeuroNames
NeuroNames
NeuroNames is an integrated nomenclature for structures in the brain and spinal cord of the four species most studied by neuroscientists: human, macaque, rat and mouse. It offers a standard, controlled vocabulary of common names for structures, which is suitable for unambiguous neuroanatomical...
) sends its connections to the spinal cord in a mostly ipsilateral manner, although there is some decussation.
It projects to the vermis in the anterior lobe, the pyramis and the uvula
Uvula
The palatine uvula, usually referred to as simply the uvula , is the conic projection from the posterior edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fibers .-Function in language:The uvula plays a role in the...
.
The paramedian nucleus also projects to the contralateral PRN, the gigantocellular nucleus
Gigantocellular nucleus
The gigantocellular nucleus, as the name indicates, is mainly composed of the so called giant neuronal cells.This nucleus has been known to innervate the caudal hypoglossal nucleus, and responds to glutamateric stimuli....
, and the nucleus ambiguous.
The paramedian reticular formation is adjacent to the abducens (VI)nucleus in the pons and adjacent to the oculomotor nucleus(III) in the midbrain.
The paramedian nucleus receives afferents mostly from the fastigial nucleus
Fastigial nucleus
The fastigial nucleus or nucleus fastigii refers specifically to the concentration of gray matter nearest to the middle line at the anterior end of the superior vermis, and immediately over the roof of the fourth ventricle, from which it is separated by a thin layer of white matter...
in the cerebellum and the cerebral cortex; however, the projections from the spinal cord are very sparse.
The descending afferent connections come mostly from the frontal and parietal lobes; however the pontine reticular formation also sends projections to the paramedian reticular nucleus.
There are also very sparse innervations from the superior colliculus
Superior colliculus
The optic tectum or simply tectum is a paired structure that forms a major component of the vertebrate midbrain. In mammals this structure is more commonly called the superior colliculus , but, even in mammals, the adjective tectal is commonly used. The tectum is a layered structure, with a...
.
Lesions in the paramedian reticular nucleus have been shown to cause a stereotyped increase in the random patterns of motion in rats. The paramedian nuclei on either side of the brain stem have been shown to mediate the horizontal eye movements on their ipsilateral sides. It seems possible that the random motion patterns of the above rats were caused by an inability to mediate their horizontal eye movements.