The human body is an amazing system that surpasses many man-made structures in its complexity. Despite this, a person acts surprisingly harmoniously and accurately, effectively fulfills assigned tasks. The movement of the body is carried out using muscles that are located almost throughout its area. Thanks to their dedicated work, we can walk, breathe, talk and do the rest, things so familiar to us.
Muscle types
The name of the human muscles came to us from ancient Rome, whose inhabitants compared the movements of muscle tissue under the skin with running mice under the sheet. Thus, for fun, the Romans called the muscles the Latin word musculus, which translates as a mouse. The comparison turned out to be so successful that they use this word to this day. “Mouse” perform their work thanks to the ability to contract. Skeletal muscles are attached by tendons to the periosteum, the connective layer of the skin, or to another muscle.
Tendons are constructed from dense connective tissue. They are extremely durable and can withstand heavy loads. In the muscle tissue, nerves pass through which signals from the spinal cord enter it, and blood vessels supply this entire complex system with fuel. 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, as, for example, human skeletal muscles . The anatomical atlas diagram also dispenses with them. From the smooth muscles, the walls of the hollow internal organs, such as the bladder, intestines, stomach, and genitals, are formed. Also, this type of muscle tissue forms the vessels along which blood and lymph move.
Unlike skeletal, smooth muscles do not obey our will. This ensures the uninterrupted operation of the most important systems of the body, interference in which could lead to negative consequences. Smooth muscle tissue is very flexible - it stretches well and can remain in this form for a long time without losing stress. This type of muscle is contracting slowly, which is perfect for the responsibilities that are assigned to it.
Striated muscle
Those muscles in which our skeleton is clothed are called striated. These are the most noticeable muscles of a person, their location scheme allows our body to perform the whole range of movements that we are used to. The mass of these muscles is about 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 performed, the muscles can be synergists or antagonists. Synergists work together to accomplish a task, while antagonists do the opposite. That is, when a muscle contracts, its antagonist must relax in order for movement to occur. The easiest way to understand this principle is the example of biceps and triceps. If you need to bend your arm, then the biceps muscle tenses, and the triceps relaxes. To extend the arm requires the opposite process. However, this does not always happen, for example, to hold the load on an outstretched arm, we need to use both the biceps and triceps. In this case, they will act as synergistic muscles.
Muscle contraction does not always occur with tension. If only the muscle length 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 without reason that it is called the main engine of our body. His continuous work ensures the life of a person, driving away liters of blood inside him. This organ consists of striated muscle tissue, which, unlike skeletal, collected in bundles, in some places intertwined. This structure allows the heart to contract quickly. Unlike skeletal muscles, the myocardium does not obey our commands, but works autonomously.
Nervous system
Within each muscle are the lines of nerves and blood vessels. Of course, it is the brain that is the starting point of the nerve impulse, but without the spinal cord there would be no way to correctly organize the human muscles. A pattern 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, both of them can be excited if the desired signal is generated.
Feedback occurs through nerve fiber, due to which the brain knows what state the muscle is in. This complex system is driven by motor neurons that receive signals in two ways. One is for conscious action, the other for reflex and automatic, such as walking, breathing or running.
Muscle groups
Muscles can be divided into separate groups, each of which has its own characteristics. The structure of the human muscles suggests their conditional division into:
These groups include the main human muscles, the layout of which is partially displayed in these groups.
Muscle and man
The work of muscles is very important for health, maintaining them in good shape is the key to a long and active life. Unfortunately, many people know about this, actively discuss the role of sport in the formation of good health, but continue to lead a sedentary lifestyle. Thus, entire muscle groups of a person remain unused.
A sedentary lifestyle causes atrophy of muscle tissue, a disease of the cardiovascular system. A pampered heart can no longer endure even minor loads, like lungs, the volume of which inevitably decreases. Remember, it is impossible to stay healthy if your muscles are constantly inactive. Provide them with work - and the result will not be long in coming.