Human Muscle Anatomy

human muscle anatomy

Before you start exercising in the gym, you need to know what muscles are, what they are and what they are intended for.

And so, the muscles of a person are organs of the human body, when contracted or relaxed, the body or individual parts of the body move. The human body consists of 430 muscles, which is approximately 50% of the total body weight.

Human muscle functions

muscle functions

By function, muscles are divided into:

1) flexors and extensors. For example, the biceps is the flexor muscle and the triceps is the extensor muscle.

2) abductor and adductor muscles. For example, if we consider such a part of the body as the shoulder, then the abductor muscles in this case will be the deltoid muscles, and the adductors will be the pectoral muscles and the latissimus dorsi.

3) synergists and antagonists. For example, the latissimus dorsi will be a synergist for the biceps, and the triceps will act as the antagonist in this case.

In relation to the joints, the muscles are distributed into:

1) single-joint – overlapping one joint.

2) multi-joint – overlapping two or more joints.

Structure of muscles and muscle fibers

Muscles consist of muscle tissue combined with connectives, blood vessels, and nerves. Muscle tissue, in turn, consists of muscle fibers.

The structure of the muscle fiber is shown in the picture.

muscle fiber structure

Muscle fibers in the human body are divided into:

1) slow oxidizing fibers or as they are called red muscle fibers.

2) fast glycolytic fibers or as they are called white muscle fibers.

Each person has an individual ratio of fast and slow muscle fibers. Moreover, different muscle fibers may predominate in different muscles. For example, a person’s biceps muscles may have more slow fibers, and their chest muscles may have more fast fibers. Determining which fibers are more can only be experimentally. Muscle fibers ratio test

Slow muscle fibers are characterized by low strength and slow fatigue. They are small in size, poorly hypertrophied and participate mainly in aerobic exercise (running or swimming for long distances, cycling, walking).

Fast muscle fibers are characterized by great strength and rapid fatigue. They are much larger in size compared to slow fibers, hypertrophy well and are mainly involved in anaerobic exercise (strength sports, running or swimming for short distances).

Hypertrophy and hyperplasia

muscle hypertrophy

Hypertrophy is an increase in muscle mass and volume. This is what we go to the gym for. When we do sports, in particular power sports, we lift weights. This, in turn, leads to micro-destruction of muscle fibers, they receive micro-injuries – micro-ruptures. After training, after a few hours, processes are started in the athlete’s body to restore damaged muscle fibers, which continue for several days.

As a result of this recovery, the muscle fibers become larger and stronger, they adapt to the previously received load. This is muscle fiber hypertrophy. Hypertrophy is subdivided into myofibrillar (an increase in the number and volume of myofibrils) and sarcoplasmic (an increase in the volume of sarcoplasm). This should be taken into account when making up a training program, because in order to achieve this or that hypertrophy, it is necessary to influence muscle fibers in different ways.

There is also such a thing as muscle fiber hyperplasia. Hyperplasia is an increase in the number of muscle fibers. It is very difficult to achieve hyperplasia, because it is much more profitable for the body to restore existing muscle fibers than to grow new ones. And recent studies have shown that the contribution of hyperplasia to the total muscle volume is no more than 5%.

Video about muscle fibers

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