thumb|240px|A dorsal root ganglion (DRG) from a chicken embryo (around stage of day 7) after incubation overnight in NGF growth medium stained with anti-neurofilament antibody. Note the axons growing out of the ganglionIn
anatomy, a
ganglion (, , plural
ganglia) is a
biological tissue mass, most commonly a mass of
nerve cell bodies. Cells found in a ganglion are called
ganglion cells, though this term is also sometimes used to refer specifically to
retinal ganglion cells.
In some dinosaurs, the ganglion in the pelvis was so large relative to its brain in its head that it could almost be said to have two brains.
Neurology
In neurological contexts, ganglia are composed mainly of
somata and
dendritic structures which are bundled or connected together. 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.
There are two major groups of ganglia:
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.
Basal ganglia
The term "ganglion" usually refers to the
peripheral nervous system.
However, in the brain (part of the
central nervous system), the "
basal ganglia" is a group of nuclei interconnected with the
cerebral cortex,
thalamus and
brainstem, associated with a variety of functions: motor control, cognition, emotions and learning.
Partly due to this ambiguity, the
Terminologia Anatomica recommends using the term
basal nuclei instead of
basal ganglia.
See also
