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A "plexus" is an integral part of the nervous system where nerves are bunched together in small groups. These nerve clusters connect the peripheral and central nervous systems, allowing electrical signals to travel from the brain and spinal cord to the rest of the body. Without these connecting bundles the brain would not be able to communicate with the rest of the body.
Nerves are strands of fibers that run through the body and provide a system where any information the brain receives can be conveyed to the rest of the body. A plexus is an area where several nerves join up before extending to the specific area they innervate or supply. There are four main nerve formations in the body for peripheral nerves located in the neck, arm pit, low back and sacral areas, and one for the central nervous system or CNS.
In the central nervous system, or the brain and spinal cord, the choroid plexus is the only nerve grouping. In this area, key blood vessels and specialized chambers called ventricles are also present. This nerve bundle differs from a peripheral nerve plexus as it is here where the cerebrospinal fluid is formed. The cerebrospinal fluid, also known as CSF, is protective watery encasement the brain and spinal cord which helps to defend against injuries and foreign invaders such as bacteria.
The peripheral nervous system, or PNS, refers to all the nerves that branch out into the rest of the body from the central nervous system. Each peripheral nerve plexus has its own set of nerves which travel together into specific areas of the body. Since each nerve in these groupings receives its own message from the brain and spinal cord, several signals can be communicated into the same area which is translated into precise movement and feeling.
The cervical plexus located in the neck area supplies information signals to the head and neck area. The brachial plexus, on the other hand, is located in the arm pit. This nerve collection is responsible for communicating with the arm and shoulder area. The grouping of nerves in the low back is called the lumbar plexus. The lumbar plexus is the communication system for the back, hip and top of the front of the thigh.
The fourth major grouping of nerves is located in the sacral area. In addition to supplying the pelvis, it also is the nerve source for the back of the thigh and the rest of the leg. Foot movements and sensations are also provided by the sacral plexus.