The human body is an amazing system that surpasses many man-made structures in its complexity. Despite this, the person acts surprisingly well-coordinated and accurately, effectively performs the assigned tasks. The movement of the body is carried out with the help of muscles, which are located almost over its entire area. Thanks to their dedicated work, we can walk, breathe, talk and do other things that are so familiar to us.
Muscle Types
The name of human muscles came to us from ancient Rome, whose inhabitants compared the movement of muscle tissue under the skin with the running of a mouse under a sheet. Thus, for fun, the Romans named the muscles with the Latin word musculus, which translates as a mouse. The comparison turned out to be so successful that this word is used to this day. The “mice” perform their work thanks to the ability to contract. Skeletal muscles are attached by tendons to the periosteum,connective layer of the skin or to another muscle.
Tendons are built from dense connective tissue. They are extremely durable and can withstand heavy loads. Nerves pass through muscle tissue, through which signals from the spinal cord enter it, and blood vessels provide fuel for this entire complex system. Depending on the structure, smooth muscles, striated, as well as cardiac muscle, or myocardium are distinguished.
Smooth muscles
This type of muscle tissue is not visible to the eye, like, for example, human skeletal muscles. The scheme from the anatomical atlas also does without them. Smooth muscles form the walls of hollow internal organs, such as the bladder, intestines, stomach, and genitals. Also, this type of muscle tissue forms vessels through which blood and lymph move.
Unlike skeletal muscles, smooth muscles do not obey our will. This ensures the uninterrupted operation of the most important body systems, intervention in which could lead to negative consequences. Smooth muscle tissue is very plastic - it stretches well and can remain in this form for a long time without losing tension. This type of muscle contracts slowly, which is perfect for the duties assigned to it.
Striated muscles
Those muscles in which our skeleton is dressed are called striated. These are the most visible human muscles, the layout of their arrangement allows our body to perform the full range of movements that we are used to. The mass of these muscles isabout 40% of the total body weight in men and 30% in women. Each muscle is attached to the skeleton so that when it contracts, movement occurs in one of the joints. The layout of human muscles resembles a mechanism that moves the body through a system of blocks and levers.
Depending on the work being done, muscles can be synergists or antagonists. Synergists work together to accomplish a given task, while antagonists do the opposite work. That is, when a muscle contracts, its antagonist must relax in order for the movement to occur. The easiest way to understand this principle is with the example of biceps and triceps. If you need to bend your arm, then the biceps tenses, and the triceps relaxes. Extending the arm requires the opposite process. However, this does not always happen, for example, in order to hold the load on an outstretched arm, we will need to use both biceps and triceps. In this case, they will act as synergistic muscles.
Muscle contraction does not always occur with tension. If only the length of the muscle changes, then this mode of operation is called isotonic. If muscle tension occurs, and its length remains the same, then such a load is called isometric.
Another interesting muscle is the heart. It is not for nothing that it is called the main engine of our body. Its continuous work ensures the vital activity of a person, driving liters of blood inside him. This organ consists of striated muscle tissue, which, inunlike the skeletal, collected in bundles, in some places it is intertwined with each other. This structure allows the heart to contract rapidly. Unlike skeletal muscles, the myocardium does not obey our commands, but works autonomously.
Nervous system
Inside each muscle there are lines of nerves and blood vessels. Of course, it is the brain that is the starting point of a nerve impulse, but without the spinal cord there would be no way to competently organize human muscles. The scheme of future movement is formed precisely in the bowels of the spinal cord, from where an ordered signal enters the muscle. Due to this, the muscles work in concert, for example, when a muscle is excited, its antagonist is inhibited. At the same time, if necessary, they can both be excited if the desired signal is generated.
Feedback occurs along the nerve fiber, thanks to which the brain knows what state the muscle is in. This complex system is controlled by motor neurons, which receive signals in two ways. One of them is for conscious actions, the other for reflex and automatic actions, such as walking, breathing or running.
Human muscle groups
Muscles can be divided into separate groups, each of which has its own characteristics. The diagram of the structure of human muscles suggests their conditional division into:
- Four-headed.
- Three-headed.
- Calf.
- Trapezoid.
- Abdominal muscles.
- Reducing.
- Muscles of the shoulders.
- Back muscles.
- Arm flexors.
- Arm extensors.
- Buttocks.
- Adductors.
- Wrist flexors.
- Wrist extensors.
- Scapular locks.
- Iciotibial muscles.
- Lumbar.
These groups include the main human muscles, the layout of which is partially displayed in these groups.
Muscles and man
Muscle work is very important for he alth, keeping them in good shape is the key to a long and active life. Unfortunately, many people know about this, actively discuss the role of sports in shaping good he alth, but continue to lead a sedentary lifestyle. Thus, entire human muscle groups remain unused.
Sedentary lifestyle causes atrophy of muscle tissue, diseases of the cardiovascular system. The pampered heart can no longer endure even minor loads, as well as the lungs, the volume of which inevitably decreases. Remember, it's impossible to stay he althy if your muscles are constantly idle. Give them a job - and the result will not be long in coming.
