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The medulla and pons also contain numerous small nuclei with a wide variety of sensory, motor, and regulatory functions. In the peripheral nervous system (PNS), a cluster of cell bodies of neurons (homologous to a CNS nucleus) is called a ganglion. The fascicles of nerve fibers in the PNS (homologous to CNS tracts) are called nerves.
Structure of a typical neuron with Schwann cells in the peripheral nervous system. Neurons are highly specialized for the processing and transmission of cellular signals. Given the diversity of functions performed in different parts of the nervous system, there is a wide variety in their shape, size, and electrochemical properties.
Neurons of the SN are notably functionally arranged roughly length-wise along the nucleus: gustatory neurons are situated rostrally (with afferents from the anterior part of the tongue and roof of oral cavity rostral-most, and those from the larynx and epiglottis more caudally placed); gastrointestinal, cardiovascular, respiratory neurons are situated more caudally.
Glia are the supporting cells of the neurons and have many functions of which not all are clearly understood, but include providing support and nutrients to the neurons. Glia are grouped into macroglia –astrocytes, ependymal cells, and oligodendrocytes, and much smaller microglia which are the macrophages of the central nervous system.
Another area, not on the dorsum of the brainstem, is where the special visceral efferents nuclei reside. These formed from the pharyngeal arches , in the embryo. This area is a bit below the autonomic motor nuclei , and includes the nucleus ambiguus , facial nerve nucleus, as well as the motor part of the trigeminal nerve nucleus.
Many voluntary movements rely on spinal lower motor neurons, which innervate skeletal muscle fibers and act as a link between upper motor neurons and muscles. [2] [3] Cranial nerve lower motor neurons also control some voluntary movements of the eyes, face and tongue, and contribute to chewing, swallowing and vocalization. [4]
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord.The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts.
Nervous tissue, also called neural tissue, is the main tissue component of the nervous system.The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain and spinal cord, and the peripheral nervous system (PNS) comprising the branching peripheral nerves.