The Musculoskeletal System and Movement

The Musculoskeletal System

The Musculoskeletal System consists of the body’s muscles, bones, tendons, ligaments and cartilage.

Bones provide the body’s structural framework, protect delicate internal organs and aid in movement by acting as levers.
Muscles, attached to bones by tendons, contract and relax to produce movement. They also maintain posture and generate heat.
Tendons attach muscle to bone and transmit the force that muscles exert to move the bones.
Ligaments hold bones together at joints, providing stability during movement.
Cartilage is a type of connective tissue found in various parts of the body including joints, where it reduces friction and acts as a cushion between bones.
The human body has 206 bones and approximately 650 muscles.

Long bones, such as the femur (thigh bone), are mostly made of compact bone tissue and are built to withstand compressive forces.
Short bones, like those found in the wrist and ankle, consist primarily of spongy bone covered by a layer of compact bone. Their primary function is providing support and stability with little to no movement.
Flat bones, such as the bones of the skull and ribs, provide extensive protection to organs and offer a large surface area for muscle attachment.
Irregular bones, such as the vertebrae and some facial bones, have complex shapes that do not fit into the other categories.

The Axial Skeleton comprises the central axis of the body, including the skull, spine, ribs and sternum.
The Appendicular Skeleton consists of the limbs and their attachment points (shoulder and pelvic girdles).

Skeletal Muscles are responsible for voluntary movement, posture and body position.
Smooth Muscles control involuntary movements in organs like stomach and intestines.
Cardiac Muscles are only found in the heart and are responsible for pumping blood throughout the body.
Muscle contraction is stimulated by nerve impulses, which are controlled by the central and peripheral nervous systems.

Synovial Joints, such as those in the knees and elbows, are the most mobile type of joint in the body.
Ball-and-Socket Joints, such as the hip and shoulder joints, allow for multi-directional movement and rotation.
Hinge Joints, like those in the knees and fingers, enable movement along a single plane, much like the hinge of a door.
Pivot Joints allow for rotation around an axis, such as the joint between the first and second vertebrae that allows the head to turn.

When a muscle contracts, it shortens, pulling on the tendon and moving the bone.
Movement is a result of a coordinated effort among various muscles. When one group of muscles contracts to move a bone in one direction, a corresponding group relaxes to allow this movement.
This muscle partnership is referred to as antagonistic muscle action. For example, the biceps and triceps work together to allow the elbow to bend (flex) and straighten (extend).