The musculoskeletal system consists of bone, muscle, cartilage and tendons. The main function of musculoskeletal system is to protect internal organs of the body and allow movement of body structure. The shape of body is given by the arrangement of musculoskeletal system.
There are 206 bones in adult. They provide the framework for tissues and cartilage. The place where bone meets, a joint is formed. The mobility of body is because of joint movement. The bones besides protection also serve various functions. Body 99% calcium is stored in bones, long bones marrow form red cells. Brain, lung and heart the most vital organ is protected by bony structure.
There are three type of muscle
1. Skeletal (voluntary) muscles are under voluntary control and provide contour and movement of body. They are attached to bones by tendons.
2. Smooth (involuntary) muscles present in gut, blood vessels control the peristalsis and blood flow.
3. Cardiac muscle in the heart, control the blood flow and distribution in whole body.
Contraction of muscles is initiated by complex array of signals arising from neurons. The synapse of neuron and muscle is called neuromuscular junction. Release of various chemicals and neurotransmitters at neuromuscular junction helps to modulate muscle contraction. Myasthenia gravis is a disease in which antibodies blocks receptors at neuromuscular junction causing muscle weakness.
Cartilage and Tendon
Cartilage is a flexible connective tissue, present between the joints, rib cage, ear, nose, bronchial tubes and intervertebral discs. The body contains three major types of cartilage: hyaline cartilage, elastic cartilage, and fibrocartilage. Hyaline cartilage is present between the joints reducing the friction, providing smooth non-jerky movement. Elastic cartilage as the name depicts recoil back to its original form, after force. It is present in ear. Fibrocartilage provides very little movement, but attaches two bones firmly, like at pubic symphysis. Tendon is fibrous connective tissue which joins muscle to bone, ligaments and fasciae are like tendon. Ligaments connect bone to bone while fasciae connect muscle to muscle. Due to sudden jerk, tendons are prone to injury.