Muscle (musculi) - the bodies ensuring the mobility of the body and its parts by voluntary and involuntary reductions. Functionally distinguish between voluntary and involuntary muscles. Involuntary muscles formed smooth muscle tissue (see). Arbitrary (striated) muscles are most of the muscles of the head, body and limbs. Basically, they are attached to various parts of the skeleton, so they are also known as skeletal muscle. Highlight of the heart muscle, which consists of striated muscle tissue, but it has a peculiar structure and reduced involuntarily.
Structural unit of the skeletal muscles is striated muscle fiber. Muscle fibers are United in bunches, connected loose connective tissue - internal perimysium. The outer surface of the muscle dressed outer perimysium. Muscle fibers form a Central part of the muscles of her abdomen. Usually the muscles are attached to the bones by tendons, built of collagen fibers and particularly those with a high resistance to tension. Muscle with blood and lymph vessels, and sensory and motor nerves, through which the communication muscles and Central nervous system.
Form distinguish muscle long, short, wide and round (sphincter). The arrangement of fibers and their attachment to the tendon - spindle and one - and deperate muscles is flat and wide, limbs were long and narrow.
A number of muscles called to the places of their beginning and attach (shoulder-beam, sternoclavicular-liner and others), shaped (diamond-shaped, gear, deltoid and others), by location (Chuck, intercostal and others). Muscle can have two heads and more, two abdomen, several tendons. There are single - or mnogocwetnye muscles. The first trigger one joint, the second - two or more joints.
To the auxiliary device muscles are fascia, synovial vagina, mucous bags, blocks and sesamoid bones. On Fig. 1 and 2 shows the muscles of a person.
At postmortem examination discover neurosis muscles in connection with the termination of delivery of blood and soil inflammation or tumor invasion; atrophy of muscles of different etiology; dystrophy when malnutrition, when denervation, adinamii; hardening, calcification of muscles and other relatively rare pathological processes.
Physiology of muscles studies the regularities of their functioning - anxiety, airway, fatigue, mechanical work.
Muscle power depends on the number of muscle fibers, included in its structure, and is proportional to the area perpendicular to its fiber - physiological cross-section muscles. Fixed point, or the starting place of muscle, and its mobile point, or the place of its attachment, can be mutually vary, depending on which part of the body in this case is more flexible. At the time of contraction is the shortening of muscles by 20-30%. The muscles or muscle groups involved in various movements, opposite one another, called antagonists. The muscles involved in one movement, called synergists. Activity of skeletal muscles occurs under the influence of impulses of the Central nervous system.