plexus

Plexus is a term used in anatomy and biology to denote a network or interwoven tangle of structures, most often nerves, blood vessels, or lymphatic vessels. The word comes from the Latin plexus, meaning braid or interlacing. In medical use, a plexus describes a branching and connecting arrangement that distributes signals or fluids across a region.

In the nervous system, plexuses organize and route nerve fibers from multiple spinal or cranial sources to broad areas of the body. The major nerve plexuses include the cervical, brachial, lumbar, and sacral plexuses. The brachial plexus, formed mainly from spinal nerves C5 through T1, consists of roots, trunks, divisions, and cords that give rise to nerves such as the radial, median, and ulnar nerves, supplying the upper limb. The lumbar and sacral plexuses supply the lower limb with nerves like the femoral and obturator nerves. Other examples include the celiac (solar) plexus in the abdomen, and various pelvic autonomic plexuses that regulate organ function. The choroid plexuses within the brain ventricles are vascular networks producing cerebrospinal fluid.

In clinical practice, plexuses are sites of interest due to their vulnerability to injury, inflammation, or compression, leading to neuropathies or pain syndromes. For example, brachial plexus damage can cause arm weakness or sensory loss; autonomic or abdominal plexuses can be involved in pain syndromes associated with abdominal or pelvic disorders. Beyond nerves, vascular and lymphatic plexuses provide interconnected pathways that facilitate blood flow and immune cell movement in tissues.