On Muscles for Bodywork


Muscle Definition

A muscle is a group of muscle tissues that contract together to produce a force. A muscle consists of fibers of muscle cells surrounded by protective tissue, bundled together with many more fibers, all surrounded in thick protective tissue. A muscle uses ATP (Adenosine triphosphate is an organic compound and hydrotrope that provides energy to drive many processes in living cells, e.g. muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis) to contract and shorten, producing a force on the objects it is connected to. There are several types of muscle, which act on various parts of the body.

Structure of Muscle

A muscle consists of many muscle tissues bundled together and surrounded by epimysium, a tough connective tissue similar to cartilage. The epimysium surrounds bundles of nerve cells that run in long fibers, called fascicles. These fascicles are surrounded by their own protective layer, the perimysium. This layer allows nerves and blood to flow to the individual fibers. Each fiber is then wrapped in an endomysium, another protective layer. As seen in the image below, a muscle is arranged in a basic pattern of bundled fibers separated by protective layers.

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Structure of Muscle

These layers and bundles allow different parts of a muscle to contract differently. The protective layer surrounding each bundle allows the different bundles to slide past one another as they contract. The epimysium connects to tendons, which attach to the periosteum connective tissue that surrounds bones. Being anchored to two bones allows movement of the skeleton when the muscle contracts. A different type of muscle surrounds many organs, and the epimysium connects to other connective tissues to produces forces on the organs, controlling everything from circulation to food processing.

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Structure of Muscle

Function of Muscle

Whether it is the largest muscle in your body or the tiny muscle controlling the movement of your eye, every muscle functions in a similar manner. A signal is sent from the brain along with a bundle of nerves. The electronic and chemical message is passed quickly from nerve cell to nerve cell and finally arrives at the motor endplate. This interface between the muscle and nerve cells releases a chemical signal, acetylcholine, which tells the muscle fiber to contract. This message is distributed to all the cells in the fiber connected to the nerve.

This signal causes the myosin proteins to grab onto the actin filaments around them. These are the purple proteins in the image below. Myosin uses ATP as an energy source to crawl along the green filament, actin. As you can see, the many small heads of the myosin fibers crawling along the actin filaments effectively shortens the length of each muscle cell. The cells, which are connected end-to-end in a long fiber, contract at the same time and shorten the whole fiber. When a signal is sent to an entire muscle or group of muscles, the resulting contraction results in movement or force being applied.

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Types of Muscle

Skeletal Muscle

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When you think of a muscle, most people generally think of a skeletal muscle. The biceps, triceps, and quadriceps are all common names for muscles that bodybuilders tend to focus on. In fact, these general muscles are often composed of many small muscles that attach to different places to give a joint its full range of motion. Skeletal muscle is a striated muscle. This means that each muscle fiber has striations, or linear marks, which can be seen when this muscle is put under a microscope. The striations correspond to the sarcomeres present in striated muscles, which are highly organized bundles of muscle cells that can contract quickly in concert.

Skeletal muscle is controlled via the somatic nervous system, also known as the voluntary nervous system. Point your finger to the ceiling. This is your somatic nervous system in action, controlling your skeletal muscles.

Cardiac Muscle

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Cardiac muscle, while similar to skeletal muscle in some ways, is connected to the autonomous nervous system. This system controls vital organs such as the heart and lungs and allows us to not have to focus on pumping our heart each time it needs to beat. While there is a certain amount of conscious control we have over the autonomous nervous system, it will always kick in when we are unconscious. For instance, you can hold your breath if you like but you do not have to remember to breathe all the time. Cardiac muscle surrounds the chambers of the heart and is used to pump blood through the body.

Cardiac muscle is similar to skeletal muscle in that it is striated. Unlike skeletal muscle, cardiac muscle fibers are arranged in a branching pattern instead of a linear pattern. Both skeletal muscle and cardiac muscle need to contract quickly and often, which is why the striations can be seen.

Smooth Muscle

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Unlike skeletal and cardiac muscle, smooth muscle is not striated. This is because the individual muscle cells are not perfectly aligned into sarcomeres. Instead, they are displaced throughout the fibers. This gives smooth muscle the ability to contract for longer, although the contraction happens more slowly. Consider the muscle that contracts the sphincter on your bladder. This muscle may need to stay clamped shut for hours at a time and only gets a minute of relief when you go to the bathroom. Many other smooth muscles operate in the same manner.

Like a cardiac muscle, smooth muscle is mostly controlled by the autonomous nervous system. The many muscles that line your digestive tract work together to move food through the digestive system. Muscles attach to your hair follicles that all your hairs to stand up when it’s cold. Smooth muscle is almost everywhere in your body and aids in everything from circulation to digestion.

Other Resources:

https://en.wikipedia.org/wiki/Muscle

https://kidshealth.org/en/kids/muscles.html

https://socratic.org/biology




Therapeutic Massage, Sports Massage Therapy in Santa Barbara, Goleta
Deep Tissue, Active Engagement (AE), Therapeutic Swedish Massage, Sports Massage Therapy in Santa Barbara, Goleta, Ca.

*Disclaimer: This information is not intended to be a substitute for professional medical advice. You should not use this information to diagnose or treat a health problem or disease without consulting with a qualified healthcare provider.
Please consult your healthcare provider with any questions or concerns you may have regarding your condition.
The information provided is for educational purposes only and is not intended as diagnosis, treatment, or prescription of any kind. The decision to use, or not to use, any information is the sole responsibility of the reader. These statements are not expressions of legal opinion relative to the scope of practice, medical diagnosis or medical advice, nor do they represent an endorsement of any product, company or specific massage therapy technique, modality or approach. All trademarks, registered trademarks, brand names, registered brand names, logos, and company logos referenced in this post are the property of their owners.

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Nicola of Riktr Pro Massage is a practicing licensed insured professional LMT (Licensed Massage Therapist) and fine artist based in Santa Barbara, CA. Nicola has a wide range of female and male clients, including athletes, professionals, housewives, artists, landscapers, out of town visitors, people who are retired and students.
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