gangliyon

Gangliyon is not a standard term in modern anatomical nomenclature, but it commonly corresponds to the concept of a ganglion: a knot-like collection of neuron cell bodies in the peripheral nervous system. The word derives from Greek, meaning knot or swelling.

There are two broad categories of ganglia: sensory ganglia and autonomic ganglia. Sensory ganglia include the dorsal root ganglia, which house the cell bodies of primary sensory neurons, and sensory ganglia of certain cranial nerves. Autonomic ganglia include sympathetic chain ganglia, prevertebral ganglia, and parasympathetic ganglia such as the ciliary and pterygopalatine ganglia. In the central nervous system, analogous clusters of neurons are typically referred to as nuclei rather than ganglia.

Structure and composition: a ganglion is usually encapsulated and consists of neuronal cell bodies surrounded by satellite glial cells, with connective tissue capsules and interconnecting nerve fibers. The arrangement supports local processing and relay of neural signals.

Function: ganglia act as relay or processing centers in the nervous system. They receive inputs from preganglionic neurons or sensory fibers and transmit or modulate signals to postganglionic neurons or effector organs, contributing to autonomic tone and sensory transmission.

Clinical relevance: ganglia can be involved in various conditions. Ganglion cysts are a common, mucin-filled lesion near joints or tendon sheaths, most often on the dorsum of the wrist; they are not true neoplasms but are related to the joint or tendon anatomy. Inflammatory or compressive processes can also affect ganglia and nearby nerves, leading to pain or neuropathic symptoms.