Ganglion
Groups of neuron cell bodies in the peripheral nervous system.
A ganglion (plural: ganglia) is a cluster of neuron cell bodies located in the peripheral nervous system. In the somatic nervous system, examples include the dorsal root ganglia and trigeminal ganglia. Within the autonomic nervous system, sympathetic and parasympathetic ganglia house the cell bodies of postganglionic sympathetic and parasympathetic neurons, respectively. These structures serve as relay points and intermediary connections between different parts of the nervous system, such as the peripheral and central systems.
Ganglia are mainly composed of somata and dendritic structures, which are bundled or linked together. They often interconnect with other ganglia to form a complex network called a plexus. Among vertebrates, there are three major groups: dorsal root (or spinal) ganglia, which contain sensory neuron cell bodies; cranial nerve ganglia, which hold the cell bodies of cranial nerve neurons; and autonomic ganglia, which contain the cell bodies of autonomic nerves. In the autonomic system, fibers from the central nervous system to the ganglia are called preganglionic fibers, while those from the ganglia to the target organ are postganglionic fibers.
A pseudoganglion resembles a ganglion but contains only nerve fibers and very few nerve cell bodies. It appears as a localized thickening of a nerve trunk, such as in the teres minor muscle and radial nerve.
The term "ganglion" originally referred to structures in the peripheral nervous system, but this restriction came after the naming of brain structures like the basal ganglia—a historical artifact in vertebrate terminology. The basal ganglia, located in the brain (part of the central nervous system), are a group of nuclei interconnected with the cerebral cortex, thalamus, and brainstem, involved in motor control, cognition, emotions, and learning. Due to this ambiguity, the Terminologia Anatomica recommends the term "basal nuclei" instead, though this has not been widely adopted. Among invertebrates, the restriction is ignored; for example, the main part of an insect brain is called the cerebral ganglion.
- field
- Neuroanatomy
- known_for
- Group of neuron cell bodies in the peripheral nervous system; relay points between peripheral and central nervous systems
Lore & Background
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. Among vertebrates there are three major groups of ganglia: dorsal root ganglia (spinal ganglia) containing cell bodies of sensory neurons; cranial nerve ganglia containing cell bodies of cranial nerve neurons; and autonomic ganglia containing 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.
Reader's Guide
The term 'ganglion' is restricted to the peripheral nervous system, though this postdates the naming of brain structures such as the basal ganglia, which remains a historical artifact in vertebrate terminology. The basal ganglia are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus, and brainstem, associated with motor control, cognition, emotions, and learning. Partly due to this ambiguity, the Terminologia Anatomica recommends using the term 'basal nuclei' instead of 'basal ganglia', but this usage has not been generally adopted. Among invertebrates the restriction is disregarded; for example, the main part of the insect brain is called the cerebral ganglion. A pseudoganglion is a localized thickening of a nerve that has the appearance of a ganglion but only has nerve fibers and no nerve cell bodies; pseudoganglia are found in the teres minor muscle and radial nerve.
Did You Know?
- A pseudoganglion looks like a ganglion but only has nerve fibers and few nerve cell bodies.
- Pseudoganglia are found in the teres minor muscle and radial nerve.
- The Terminologia Anatomica recommends using 'basal nuclei' instead of 'basal ganglia', but this has not been generally adopted.
- Among invertebrates, the main part of the insect brain is called the cerebral ganglion.
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