Flexin’: Part 2, Muscle Anatomy

In my last post that began this series on muscles, I introduced the concept–and definition–of training. In this post, I introduce the anatomy of the muscles.

Muscles are soft tissue found in animals and come in three varieties: skeletal, the voluntary muscles used to affect movement of the body; smooth, involuntary muscles found in organs; and cardiac, which is another involuntary muscle found in the heart. Skeletal muscles, the ones focused on in exercises, are anchored to bone by tendons and are used to move the body, maintain balance and posture and circulate blood throughout the body.

Tendons are the connective tissues that transmit the mechanical force of muscle contraction to the bones; the tendon is firmly connected to muscle fibres at one end and to the bone at the other. Tendons are very strong, given that they must withstand the stress generated from muscle contraction.


Ligaments are bands connective tissue that supports the internal organs, but mostly connects bones together, known as the joint, or articulation; it is an area where two bones are attached for the purpose of motion of body parts.



muscle structure

Skeletal muscles are organized in a hierarchical structure, like an inverted pyramid. They are enveloped by connective tissue called the epimysium, which anchors the muscles to the tendons and protects the muscle from friction against other muscles and bones. Within the epimysium, fascicles—the next sub-level in the hierarchy—are bundles of at least 10 to 100, or more, muscle fibres come together. These muscle fibres that form the fascicles are enclosed by connective tissue called the perimysium. The perimysium is not just a name I threw out there to sound erudite, rather it has a function: this is the pathway through which nerves and blood flow to the muscle. Individual muscle cells form the threadlike muscle fibres.

muscle anatomy

On a micro level, the muscle cells are in keeping with the hierarchical structure; muscle cells are composed of bundles of myofibrils, which are complex strands of several kinds of protein filaments (a slender, threadlike fibre), called myofilaments, organized together into repeating units called sarcomeres. The myofilament is where muscle contraction happens, so you may want to tuck this piece of info away, too. The arrangement of the sarcomeres is what gives the muscles a striped, or striated, appearance. The myofilament is either a thin or think filament, each with a different protein for different functions: actin, the thin filament protein in used to generate motion, whereas myosin is the thick filament protein used to generate force. These two filaments slide past each other, overlapping, as the myofibril expands and contracts.

muscle scale


That was dense and heavy and here is where I end Part 2.

You have to know the rules to break the rules




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