The work of the Muscles

The human body has more than 650 muscles, including 50 facial muscles. Apart from muscles, the human musculoskeletal system is composed of bones, joints, tendons and ligaments. Generally speaking, muscles serve to make different parts of the body move. Aside from adhering to the bones, muscles also line the insides of organs, e.g. the heart or the lungs.


What types of Muscles are there?

There are different types of muscles in the body: so-called 'skeletal' musculature or 'striated' musculature, and 'smooth' musculature. Cardiac and skeletal muscles are 'striated', while the 'smooth' muscles are present i.e. in the digestive tract. Tendons connect the muscles to the bones and can be controlled via nerve impulses. This is how they know when to contract or to relax. For example, 17 muscles work together to create a smile. And 30 different muscles are involved to move hands and fingers.

The biggest muscle in the human body is the gluteal muscle, which controls the movement of our legs. At just 0.3 millimeters in length, the stapedius muscle in our ear is the smallest muscle.

A muscle is composed of multiple bundles made of muscle cells and muscle fibers. Men usually have a muscle percentage of 40-60 percent of their body weight, whereas the female body has a muscle percentage of 30-40 percent. With age, muscle percentage decreases in women and men alike. The muscles in the legs, in particular, are prone to atrophy, which is why we should pay extra attention to our leg muscles.


Muscles – the engine in our body.
Muscles – the engine in our body.

How do Muscles work?

A complex process permits muscles to move. In this case, small muscle fibers contract and relax. Starting at the small muscle cells, these contractions propagate to the muscle fibers and muscle bundles so that in the end the entire muscle moves. Every single muscle in our body is able to perform a certain movement in a particular direction. However, there is always some kind of counterpart steering the movement in the exact opposite direction. For example, the biceps and the triceps are counterparts in the upper arm which help bend and stretch the arm.

Together they are strong. Thousands of cells move so that the muscle can use its full power. For instance, to flex the forearm, the biceps need to contract. Tendons connect the biceps to the shoulder and to the bone in the forearm. Both bones move towards each other when using the muscle and hence the elbow joint bends. At the same time, the muscles' counterpart, the triceps, are relaxed. This burns a lot of energy. Approximately 25 percent of the energy is required for the mechanical movement and the other 75 percent is converted into heat.

Muscles not only help us breathe, make our heart beat and provide warmth – they enable physical activity in our everyday life, they act as a power unit or, metaphorically speaking, as the engine of the human body.


Bones      Joints


A man runs using his knee muscles.
Muscles function as a kind of engine in our body.