3 Rules of Muscles

The 3 Rules of Muscles: Understanding How They Work

Muscles are one of the key pillars of our movement system. They are special tissues with a unique ability: to contract and relax. This process allows us to perform everything from simple to complex movements. However, to fully harness their potential, it’s important to understand a few key rules about how muscles work. Here are the three main rules you need to know:

1. Muscles only contract and relax. Muscles have a unique action: they contract to generate force and relax to return to their original state. On their own, they cannot stretch or expand; this action depends on other factors such as tendons and external forces. Simply put, muscles only act in two directions: they contract (shorten) and relax (lengthen).
2. Muscles only work on joints they cross. It’s important to remember that a muscle can only generate movement on a joint it crosses. For example, the biceps brachii only affects the elbow joint because that’s the only joint it crosses. If a muscle doesn’t cross a joint, it cannot influence its movement.
3. Muscles work best in the direction of their fibers. The orientation of muscle fibers determines the direction in which the muscle generates force. Muscles are designed to work most efficiently in the direction their fibers are aligned. For example, long muscles like the sartorius, which have fibers aligned diagonally, have a wider range of action, while shorter, thicker muscles, like those in the back, are designed to generate force in more compact movements.

Muscle Tissue: Characteristics and Function

Muscle tissue is a type of tissue with the unique characteristic of being able to contract and relax. This ability allows it to generate the necessary force to move the body, from the involuntary movements of the heart to the voluntary movements of the limbs. Additionally, muscle tissue is specialized to transmit electrical signals that coordinate its actions.

The Etymology of “Muscle”: A Link to the Past

The word “muscle” has an interesting etymology. It comes from the Latin musculus, meaning “little mouse,” a diminutive of mus, meaning “mouse.” This reference to a mouse relates to the appearance of muscles when they move beneath the skin, as they contract and relax, resembling the movement of a mouse under the skin. This poetic image highlights the ability of muscles to generate movement and energy.