The average person's muscle accounts for 35%-40% of the body weight. The total length of capillaries in muscle can reach 654.38+ million kilometers, which can circle the earth twice and a half times.
Every muscle that constitutes a motor organ is a complex organ, which consists of muscle abdomen and tendon.
Extended data:
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.
Muscle contraction pulls bones to produce joint movement, which acts like a lever device and has the following functions:
1, the balance bar moves, and the fulcrum is between the key point and the force point, such as the up-and-down movement of the atlanto-occipital joint.
2, labor-saving lever action, its focus is between the fulcrum and the stress point, such as the ankle action when starting to lift the heel.
3. Speed bar movement, the stress point is located between the key and the fulcrum, such as the movement of the elbow joint when lifting heavy objects.
Reference source: Baidu Encyclopedia-Muscle