What is ganglion?

In anatomy, a ganglion (plural ganglia) 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 and efferent nerves.

In a neurological context, ganglia are composed mainly 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.