The reticulotegmental nucleus, tegmental pontine reticular nucleus (or pontine reticular nucleus of the tegmentum) is an area within the floor of the

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of Va ...

, in the brain stem. This area is known to affect the

cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...

with its

axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...

al projections. These afferent connections have been proven to project not only ipsilaterally, but also to

decussate Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (), ). In Latin anatomical terms, the form is used, e.g. . Similarly, the anatomical term chiasma is named aft ...

and project to the contralateral side of the

vermis The cerebellar vermis (from Latin ''vermis,'' "worm") is located in the medial, cortico-nuclear zone of the cerebellum, which is in the posterior fossa of the cranium. The primary fissure in the vermis curves ventrolaterally to the superior s ...

. It has also been shown that the projections from the

pontine tegmentum Pontine may refer to: * Having to do with the pons, a structure located in the brain stem (from ''pons'', "bridge") * Pontine Marshes, a region of Italy near Rome * Pontine Islands The Pontine Islands (, also ; it, Isole Ponziane ) are an ar ...

to the cerebellar lobes are only crossed fibers. The reticulotegmental nucleus also receives efferent axons from the

. This nucleus is known for its large number of

multipolar cells A multipolar neuron is a type of neuron that possesses a single axon and many dendrites (and dendritic branches), allowing for the integration of a great deal of information from other neurons. These processes are projections from the neuron cell ...

and its particularly reticular structure. The reticulotegmental nucleus is topographically related to pontine nuclei (non-reticular), being just dorsal to them. The reticulotegmental nucleus has been known to mediate eye movements, otherwise known as

saccadic A saccade ( , French for ''jerk'') is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishi ...

movement. This makes sense concerning their connections, as it would require a nucleus that receives and projects to the cerebellum to mediate that kind of complex circuitry. Furthermore, in terms of behavior, one does not ''think'' about saccadic movements when scanning a room, as the saccadic movements are not directly controlled by the cortex. The pontine nuclei are the most traditionally studied mostly because it is easy to see which nuclei degrade when the cerebellum is amputated. The neurons of the lateral reticular formation are very important for reflexes and the mediation of

posture Posture or posturing may refer to: Medicine * Human position ** Abnormal posturing, in neurotrauma **Spinal posture ** List of human positions * Posturography, in neurology Other uses * Posture (psychology) In humans, posture can provide a s ...

. It has been shown in

cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

s that electrical stimulation of the reticular formation can make a standing cat lie down. Also, stimulation of the cat in an alternative spot can make a lying cat stand.

References

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