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Extensor retinaculum is a connective tissue that is part of the musculoskeletal system and found only in select regions of the body. This structure is used for stability and protection of the extensor muscles in the forearm and top of the foot. All types of extensor retinaculum need to be kept healthy for proper joint function. In some cases, problems with this tissue can result in painful disorders such as tendinitis and carpal tunnel syndrome. Other times, diseases such as diabetes can cause problems that result in extensor retinaculum pain or discomfort.
Truly understanding what extensor retinaculum is requires exploring the design and function of connective tissue. This type of connective tissue, called fascia, is used to house the extensor muscles of the posterior annular ligament. It provides support for the muscles under it and also helps keep that muscle group in place. Other structures, known as the synovial tendon sheaths, work with the retinaculum to keep extensor muscle tendons stabilized.
Extensor retinaculum is found on the posterior portion of the forearm near the wrist when the arm is held in anatomical position, the universally recognized body position of the upright body with the hands and arms held with the thumbs pointing away from the body. On the forearm, extensor retinaculum forms a wide band of connective tissue covering the extensor muscle group’s delicate tendons, which function to provide attachments for the muscles of the hand and forearm. Extensor retinaculum is also located on the dorsal aspect of the foot; in layman's terms, that’s the top of the foot. Just as with the forearm, this retinaculum is present for protection of the tendons that allow for extension of the foot. Those muscles and tendons are used in actions such as pointing the toes, walking, and various other motions.
The most common disorder or injury of either extensor retinaculum is inflammation, though it is a problem more commonly found in the forearm. When this inflammation of the retinaculum — and the synovial tendon sheaths — occurs, the median nerves close to the hand can be impinged and experience restricted movement. In some cases, this condition can be treated conservatively with medications and physical therapy, but it isn't uncommon for surgery to be needed to move the inflamed tissue away from the nerves.