1. Skeletal muscle is the kind of muscle that people often say. It is attached to the bones through tendons and distributed in the trunk and limbs. Biceps biceps brachii, triceps brachii, quadriceps femoris, biceps femoris, abdominal muscles and pectoral muscles all belong to skeletal muscles. It is the motive force of human movement, and the main object of fitness and muscle enhancement is skeletal muscle.
2. Cardiac muscle This "cardiac muscle" is not "heart", but it is as important as "heart". It is distributed near the heart and the great blood vessels adjacent to the heart. Myocardial contraction has automatic rhythm, slow and lasting, not easy to fatigue, not dominated by consciousness.
3. Smooth muscle Smooth muscle is widely distributed in blood vessel wall and many internal organs, so it is also called "visceral muscle". The contraction of smooth muscle is slow and persistent.
Composition structure
There are about 639 human muscles. It consists of about 6 billion muscle fibers, the longest is 60 cm, the shortest is only about 1 mm, the big muscle weighs about two kilograms, and the small muscle weighs only a few grams. The average person's muscles account for about 35% to 45% of the body weight.
According to the different structure and function, it can be divided into smooth muscle, myocardial muscle and skeletal muscle, and according to the shape, it can be divided into long muscle, short muscle, flat muscle and orbicularis oris muscle. Smooth muscle is mainly composed of internal organs and blood vessels, which has the characteristics of slow contraction, long duration and no fatigue. Myocardium constitutes the heart wall, and neither of them contracts with human will, so it is called involuntary muscle.
Skeletal muscles are distributed in the head, neck, trunk and limbs, and are usually attached to bones. Skeletal muscle contracts rapidly, forcefully and easily, and can contract and contract with people's will, so it is called voluntary muscle. Skeletal muscle is striated under the microscope, so it is also called striated muscle.