Epimysium is a type of connective tissue that completely surrounds and encases muscles in humans and many animals. It acts as a sort of buffer that protects muscles from rubbing into bones or other muscular fibers, and promotes smooth movement in the limbs and most joints. Nearly every muscle in the body has this sort of protective casing. Beyond serving as an insulator, it also plays an important role in the formation of tendons, which act as thick cord-like structures that facilitate tension and movement. Deep tissue massages known as myofascial massages often target the epimysia of many of the body’s biggest muscle groups, both as a way of releasing pressure and tension and relieving pain. The tissue’s proximity to major muscles makes it a good conductor of targeted energy.
Where to Find It
This tissue layer essentially acts as the outermost shell or casing for most muscles. As such, it’s more or less ubiquitous in the body. Humans and animals depend on the musculoskeletal system for everything from basic weight stability to movement and reflexes. Muscles are more than just strong strips of flesh, though, and tend to have their own complicated anatomy that helps them do their job well.
At a very elemental level, muscles are made of individual fibers, each covered by a protective layer known as the endomysioum, that are bundled together to form a muscle fascicle. A layer called the “perimysium” holds the fascicles and a number of blood vessels and nerve tissues in an even bigger bundle, which is enclosed at the top by epimysium fibers.
What It’s Made Of
Epimysia differ from perimysia and endomysium primarily in location. From a composition standpoint, all are very similar. All three layers are dense, irregular connective tissue that consists primarily of tightly packed fibroblasts and collagen fibers without any particular directional orientation. Together they are part of the fascia — a grid of dense, irregular, connective tissue that lines the muscles and subcutaneous layer.
There are many different biological purposes for this outermost layer, but protection from strain and friction is one of the most important. The smoothness of the tissues promotes seamless gliding, and can also protect joints and other high-impact areas from rips or tears. Muscles tend to be strong, but they can be damaged, particularly in the event of accidents or overuse. A tough fibrous coating can provide a bit of cushion against this.
The epimysium of any muscle also plays a role in tendon formation and anchoring, along with the perimysium and endomysium. These components flow together into the insertion of the muscle where they combine to form a tendon cord. This tendon pulls on the insertion of the muscle while the origin remains stationary, thereby causing movement. For example, tendons in the upper arm cross over to the forearm over the inside of the elbow. When muscles of the upper arm contract, they pull on their tendons, which pull on the forearm and cause various different types of motion.
Role in Stress Release
People often carry a lot of tension in their muscles, both from everyday stress and strains caused by posture, heavy lifting, or many hours spent standing. Those who suffer from muscular disorders also frequently have a lot of pain in their major muscle bands. Myofascial massage is a type of massage that focuses on the fascia, including the epimysium around muscles. This type of massage is often classified as “therapeutic,” which means that it’s designed more for a medial purpose than a general feeling of relaxation as might be sought in a spa. Massage therapists who perform this sort of procedure often work in physical therapists’ offices or in medical rehabilitation clinics, though there are some exceptions.
Myofascial massage is often painful at first, as the fascia and muscles are stretched and rolled beyond what a person may be used to. With time and regular treatments, however, patients usually report a reduction in pain, joint stress, and muscle fatigue.