The muscular system is the biological system of humans that produces movement.
Skeletal muscles are attached to bones by tendons, and they produce all the movements of body parts in relation to each other. Unlike smooth muscle and cardiac muscle, skeletal muscle is under voluntary control. Similar to cardiac muscle, however, skeletal muscle is striated; its long, thin, multinucleated fibres are crossed with a regular pattern of fine red and white lines, giving the muscle a distinctive appearance. Skeletal muscle fibres are bound together by connective tissue and communicate with nerves and blood vessels.
There are more than 600 skeletal muscles in the human body, which together account for about 40 percent of a person’s weight. Skeletal muscles are also called voluntary muscles because, unlike the other two types of muscle in the body, smooth muscle and cardiac muscle, they are under conscious control.
Skeletal Muscles are those which attach to bones and have the main function of contracting to facilitate movement of our skeletons. They are also sometimes known as striated muscles due to their appearance. The cause of this ‘stripy’ appearance is the bands of Actin and Myosin which form the Sarcomere, found within the Myofibrils.
Skeletal muscles are also sometimes called voluntary muscles, because we have direct control over them through nervous impulses from our brains sending messages to the muscle. Contractions can vary to produce powerful, fast movements or small precision actions. Skeletal muscles also have the ability to stretch or contract and still return to their original shape.
Muscle is contractile tissue and is derived from the mesodermal layer of embryonic germ cells. Its function is to produce force and cause motion, either locomotion or movement within internal organs. Much of muscle contraction occurs without conscious thought and is necessary for survival, like the contraction of the heart or peristalsis, which pushes food through the digestive system. Voluntary muscle contraction is used to move the body and can be finely controlled, such as movements of the finger or gross movements that of the biceps and triceps.
SKELETAL MUSCLE FIBRE TYPE
Not all fibres within Skeletal muscles are the same. Different fibre types contract at different speeds, are suited to different types of activity and vary in colour depending on their Myoglobin (an oxygen carrying protein) content.
MAJOR SKELETAL MUSCLES CONCERNED WITH BODYBUILDING
- Upper Arm –Anterior – Biceps muscle and Posterior- triceps muscle.
- Forearm – Brachioradialis muscle
- Shoulders – Deltoid muscle
- Chest – Pectoralis muscle
- Collar – Trapezius muscle
- Upper back – Latissimus dorsi muscle
- Lower back – Erector spinae muscle
- Abdomen – Rectus abdominus muscle
- Buttocks – Gluteus muscle
- Front thighs – Quadriceps muscle
- Back thighs – Hamstring muscle
- Calves – Gastrocnemius muscle