A ganglion is a nerve cell cluster or a group of nerve cell bodies located in the autonomic nervous system and sensory system. Ganglia house the cell bodies of afferent nerves (input nerve fibers) and efferent--output/motor--nerve fibers, or axons.
A pseudoganglion looks like a ganglion, but only has nerve fibers and has no nerve cell bodies.
Ganglia are primarily made up of somata and dendritic structures which are bundled or connected. Ganglia often interconnect with other ganglia to form a complex system of ganglia known as a plexus. Ganglia provide relay points and intermediary connections between different neurological structures in the body, such as the peripheral and central nervous systems.
Among vertebrates there are three major groups of ganglia:
- Dorsal root ganglia (also known as the spinal ganglia) contain the cell bodies of sensory (afferent) neurons.
- Cranial nerve ganglia contain the cell bodies of cranial nerve neurons.
- Autonomic ganglia contain the cell bodies of autonomic nerves.
In the autonomic nervous system, fibers from the central nervous system to the ganglia are known as preganglionic fibers, while those from the ganglia to the effector organ are called postganglionic fibers.
However, in the brain (part of the central nervous system), the "basal ganglia" is a group of nuclei interconnected with the cerebral cortex, thalamus, and brainstem, associated with a variety of functions: motor control, cognition, emotions, and learning.
Partly due to this ambiguity, the Terminologia Anatomica recommends using the term basal nuclei instead of basal ganglia; however, this usage has not been generally adopted.
A pseudoganglion is a localized thickening of the main part or trunk of a nerve that has the appearance of a ganglion but has only nerve fibers and no nerve cell bodies.
- Sadava, David; Heller, H. Craig; Orians, Gordon H.; Purves, William K.; Hillis, David M. (2008). Life: The Science of Biology (8th ed.). W. H. Freeman. p. 943. ISBN 9780716776710.
- "ganglion" at Dorland's Medical Dictionary
- Brodal, Per (2010). The Central Nervous System. Oxford University Press. p. 5. ISBN 9780195381153.
In the CNS, such a group is called a nucleus and in the peripheral nervous system (PNS), a ganglion.
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- Media related to Ganglia at Wikimedia Commons