The muscles are tissues or organs of the human body, of the musculoskeletal system characterized by its ability to contract and generally a response to nerve stimulation; The basic unit of the muscle is the myofibril, a very small filiform structure that in turn is made up of complex proteins, thus being the most adaptable organ and undergoing modifications that no other organ in the body can go through its content and shape, Being thus damaged by some atrophy, it recovers, reinforcing itself over time, if it is abused or as if it is not used, it is damaged in the same way, reducing the size of the muscle itself and its strength, as well as the cells that maintain it. stuck to the bones.
There are three types of muscle tissue: smooth, skeletal tissue, and cardiac. The smooth muscle is visceral or involuntary muscle, composed of spindle - shaped cells with a central core; This muscle is located in the skin, internal organs, reproductive system, large blood vessels and excretory system, being found in other organs that are made up of other tissues such as the heart and intestine, which contain layers of connective tissue.
The muscle tissue is composed of long fibers and surrounded by a cell membrane called sarcolemma, most are attached to various areas of the skeleton by tendons hence the name, forming most of the body mass of the vertebrate; the retracting action is often visible on the skin. The cardiac muscle forms most of the heart and lacks voluntary control, since it is innervated by the vegetative nervous system, its mechanism of cardiac contraction being based on the generation and automatic transmission of impulses.
The functions of the muscles are to produce movement, generate mechanical energy, joint stability, protect by involuntary stimuli, maintain posture, provide heat, stimulate blood vessels and lymphatics and provide information on any damage that has occurred anywhere in the body. The main muscles of the human body are: the arms, the legs, the abdomen, the back and the buttocks.
