peri-
(Greek: around, enclosing, surrounding, about, near, close; often used as a prefix)
2. Near or around a ganglion.
The celebrated 2nd century Greek physician, Galen (about 130-201 A.D.), who lived and worked in Rome first used the word ganglion to refer to a nerve complex.
Ganglion still is used to refer to an aggregation of nerve cell bodies. Another use of the word ganglion is for a tendon cyst that most commonly pops up near the wrist.
A ganglion is a sac-like swelling or cyst formed from the tissue that lines a joint or tendon. The tissue, called synovium, normally functions to produce lubricating fluid for these areas.
A ganglion is a cyst formed by the synovium that is filled with a thick jelly-like fluid. While ganglia can follow local trauma to the tendon or joint, they usually form for unknown reasons. Occasionally, ganglia are early signs of arthritis that will become more obvious in the future.
A perigee is the point in any orbit nearest to the body being orbited.