ganglios

Ganglia, or ganglios in some languages, are clusters of neuronal cell bodies located outside the central nervous system. They serve as relay and processing stations for neural signals, organizing sensory information from the periphery before it reaches the brain and coordinating autonomic output to various target organs.

There are two main categories of ganglia. Sensory ganglia include the dorsal root ganglia and cranial nerve ganglia such as those associated with the trigeminal and vestibulocochlear nerves. Autonomic ganglia are part of the sympathetic and parasympathetic divisions and include paravertebral, prevertebral (collateral), and intramural ganglia located near or within target organs.

Structurally, ganglia are encapsulated by connective tissue and contain neuron cell bodies, typically pseudounipolar neurons in sensory ganglia, surrounded by satellite glial cells. The ganglion houses the proximal processes of neurons whose distal axons extend to receptors or the CNS, and it receives synaptic inputs within the ganglionic environment. Vascularization includes small arteries and veins that supply both neurons and glial elements.

Developmentally, ganglia arise mainly from neural crest cells, which differentiate into neurons and supporting glial cells. Clinically, dorsal root and cranial nerve ganglia can be sites of herpes zoster reactivation, causing radicular pain and rash. Neural crest–derived ganglia can develop tumors such as ganglioneuromas, gangliogliomas, or neuroblastomas. Damage or dysfunction of ganglia can contribute to neuropathic pain and autonomic disorders.

In summary, ganglia are essential peripheral nervous system structures that process and relay sensory information and regulate autonomic function, with diverse locations and clinical significance.