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The nervous system segmentation confers several developmental advantages to the vertebrate body as humans possess a body plan that is bilaterally segmented at the nervous system level. The segmentation is involved at all levels of the human nervous system with increasing level of complexity in the innervation from the brain to limbs. [1]
The following diagram is provided as an overview of and topical guide to the human nervous system: Human nervous system. Human nervous system – the part of the human body that coordinates a person's voluntary and involuntary actions and transmits signals between different parts of the body.
The impulse travels from these upper motor neurons (located in the pre-central gyrus of the brain) through the anterior column. In contrast to the fibers for the lateral corticospinal tract, the fibers for the anterior corticospinal tract do not decussate at the level of the medulla oblongata , although they do cross over in the spinal level ...
Wound scars in the brain largely contain astrocytes. The extracellular matrix also provides support on the molecular level for the brain's cells, vehiculating substances to and from the blood vessels. At the organ level, the nervous system is composed of brain regions, such as the hippocampus in mammals or the mushroom bodies of the fruit fly. [11]
As cells within the paraxial mesoderm begin to come together, they are termed somitomeres, indicating a lack of complete separation between segments. The outer cells undergo a mesenchymal–epithelial transition to form an epithelium around each somite. The inner cells remain as mesenchyme.
Afferent nerve cell bodies bring information from the body to the brain and spinal cord, while efferent nerve cell bodies bring information from the brain and spinal cord to the rest of the body. The cell bodies create long sympathetic chains that are on either side of the spinal cord. They also form para- or pre-vertebral ganglia of gross anatomy.
This is the segmental organization of its cervical, thoracic, lumbar, and sacral components, which is arranged from most medial to most lateral respectively. The pathway crosses over ( decussates ) at the level of the spinal cord, rather than in the brainstem like the dorsal column-medial lemniscus pathway and lateral corticospinal tract .
The human cerebellum contains on the order of 60 to 80 billion granule cells, making this single cell type by far the most numerous neuron in the brain (roughly 70% of all neurons in the brain and spinal cord, combined). Golgi cells provide inhibitory feedback to granule cells, forming a synapse with them and projecting an axon into the ...