ganglion

A ganglion, in anatomy, is a collection of nerve cell bodies located in the peripheral nervous system. They are typically surrounded by a connective tissue capsule and satellite glial cells, and they are found along nerves outside the brain and spinal cord. The neurons in ganglia relay and modulate sensory, autonomic, or motor signals between peripheral nerves and the central nervous system.

In vertebrates, several major categories exist: dorsal root (sensory) ganglia adjacent to the spinal cord; cranial nerve ganglia such as the trigeminal and glossopharyngeal ganglia; and autonomic ganglia including sympathetic chain ganglia and parasympathetic terminal ganglia near target organs. Neuron cell bodies in ganglia contrast with nerve fibers, which carry impulses into and out of the ganglion.

Ganglia are involved in the processing and transmission of information within the peripheral nervous system. They can be sites of disease when they become inflamed, enlarged, or lesioned, and certain conditions can affect sensation or autonomic function through ganglionic dysfunction or tumor formation, such as paragangliomas arising from autonomic ganglia.

Ganglion cyst: A different use of the term refers to a noncancerous, fluid-filled lump commonly on the hand or wrist. It arises near joint capsules or tendon sheaths and contains viscous fluid. Most resolve spontaneously; treatments include observation, aspiration, or surgical removal, though recurrence can occur.

The term ganglion derives from Greek, meaning knot or swelling.