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In anatomy, the extrapyramidal system is a part of the motor system network causing involuntary actions. [1] The system is called extrapyramidal to distinguish it from the tracts of the motor cortex that reach their targets by traveling through the pyramids of the medulla .
In human anatomy, the extrapyramidal system is a neural network located in the brain that is part of the motor system involved in the coordination of movement. [2] The system is called "extrapyramidal" to distinguish it from the tracts of the motor cortex that reach their targets by traveling through the "pyramids" of the medulla.
Extrapyramidal symptoms (EPS) are symptoms that are archetypically associated with the extrapyramidal system of the brain's cerebral cortex. When such symptoms are caused by medications or other drugs, they are also known as extrapyramidal side effects (EPSE). The symptoms can be acute (short-term) or chronic (long-term).
The pyramidal tracts include both the corticobulbar tract and the corticospinal tract.These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar) or spinal cord (corticospinal) and are involved in the control of motor functions of the body.
In humans, the tectospinal tract (or colliculospinal tract) is a decussating extrapyramidal tract that coordinates head/neck and eye movements. [1]It arises from the superior colliculus of the mesencephalic (midbrain) tectum, and projects to the cervical and upper thoracic spinal cord levels. [2]
The substantia nigra is located in the ventral midbrain of each hemisphere. It has two distinct parts, the pars compacta (SNc) and the pars reticulata (SNr). The pars compacta contains dopaminergic neurons from the A9 cell group that forms the nigrostriatal pathway that, by supplying dopamine to the striatum, relays information to the basal ganglia.
It is a part of the lateral indirect extrapyramidal tract. The rubrospinal tract fibers are efferent nerve fibers from the magnocellular part of the red nucleus. (Rubro-olivary fibers are efferents from the parvocelluar part of the red nucleus). [2] It is functionally less important in humans. [3]
The corticobulbar (or corticonuclear) tract is a two-neuron white matter motor pathway connecting the motor cortex in the cerebral cortex to the medullary pyramids, which are part of the brainstem's medulla oblongata (also called "bulbar") region, and are primarily involved in carrying the motor function of the non-oculomotor cranial nerves, like muscles of the face, head and neck.