Human musculoskeletal system

The human musculoskeletal system (also known as the human locomotor system) is an organ system that lets humans move using their muscular and skeletal systems. It gives the body shape, support, and helps it move.

This system is made of the bones of the skeleton, muscles, cartilage, tendons, ligaments, joints, and other connective tissue. These parts work together to hold up the body, let it move, and protect important organs. Bones store calcium and phosphorus and help make parts of the hematopoietic system.

Muscles attach to bones through tendons and help move the bones by squeezing. Joints connect bones and let them move, while cartilage stops bones from rubbing together. When muscles and joints work together, they help the body move smoothly.

Sometimes, illnesses or injuries can make it hard to move normally. Experts like a physiatrist (a specialist in physical medicine and rehabilitation) or an orthopaedic surgeon help fix these problems.

Subsystems

Skeletal

Main article: Human skeleton

The skeletal system gives our body its shape and supports and protects us. It helps us move, makes blood, and stores important minerals. Babies are born with over 300 bones, but many of these bones join together as we grow. By adulthood, we usually have 206 bones. Bones come in different shapes, like long bones, short bones, flat bones, irregular bones, and sesamoid bones. The skeleton has two main parts: the axial skeleton, which includes the spine, and the appendicular skeleton, which includes the arms and legs. Bones are held together by ligaments, tendons, muscles, and cartilage.

The skeletal system also protects important parts of our body. For example, the skull protects the brain, and the rib cage protects the lungs. Inside long bones, there is a special substance called bone marrow. One type, red marrow, helps make new blood cells. Another type, yellow marrow, stores fat that the body can use for energy when needed. Bones also store minerals like calcium and phosphorus, which help keep our blood healthy.

Muscular

Main article: Muscle

There are three types of muscles in our bodies. Smooth muscles help control the flow of substances inside hollow organs and we cannot control them ourselves. Skeletal and cardiac muscles have stripes that can be seen under a microscope. Only skeletal and smooth muscles are part of the musculoskeletal system, and they are the ones that can move our body. Cardiac muscles are found in the heart and help pump blood, but we cannot control them either. Skeletal muscles are attached to bones and work in groups around joints. When nerves send signals from the brain, these muscles contract and move our body.

A tendon is a strong band of tissue that connects muscles to bones. When muscles contract, tendons pull on the bones, causing us to move. Tendons can stretch and help us save energy when we walk or run.

Joints, ligaments and bursae

Main article: Joint

Joints are where bones meet and they let us move. There are different types of joints. Some, like synovial joints, allow a lot of movement and are lubricated by a special fluid called synovial fluid, which helps reduce friction. Ligaments are tough bands of tissue that connect bones to each other at the joints. They help keep the bones in place and prevent certain movements that could be harmful.

Bursae are small, fluid-filled sacs found near joints. They act as cushions between bones, tendons, and muscles, helping to reduce friction and make movement smoother.

Clinical significance

Further information: Musculoskeletal disorders, Rheumatology, and Orthopedic surgery

Problems with the musculoskeletal system can happen when other body parts, like blood vessels, nerves, or skin, are not working well. This can make it hard to know what is causing the trouble.

The most common issues are with the joints. Other problems can include muscles not working right, issues with the nervous system, or problems from infections or harmful substances.

Sometimes, muscle problems can affect other parts of the body, like making it hard to move the eyes, breathe, or control the bladder. These problems can be caused by infections or harmful substances, but often they are linked to the nervous system.

One problem that can start during pregnancy is pain in the pelvic area. This pain can be caused by changes in muscles or ligaments, and it can affect how a person moves.